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Sample records for fretting wear behavior

  1. Fretting wear behavior of AZ91D magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN An-hua; HUANG Wei-jiu; LI Zhao-feng

    2006-01-01

    The fretting behaviour of the AZ91D magnesium alloy was investigated. The influence of the number of cycles, normal load (contact pressure) and the amplitude of slip on the fretting behavior of the material were focused. Fretting tests were performed under various running conditions with regard to normal load levels and slip amplitudes. The friction coefficient between the surfaces at the fretting junction was continuously recorded. The fretting damage on the magnesium specimens was studied by SEM. The results show that the wear volume increases with the increase of slip amplitude, and linearly increases with the increase of normal load in the mixed and gross slip regime, but the normal load has no obvious effect on the wear volume in the partial slip regime. The predominant fretting wear mechanism of magnesium alloy in the slip regime is the oxidation wear, delaminated wear and abrasive wear.

  2. Impact Fretting Wear Behavior of Alloy 690 Tubes in Dry and Deionized Water Conditions

    Science.gov (United States)

    Cai, Zhen-Bing; Peng, Jin-Fang; Qian, Hao; Tang, Li-Chen; Zhu, Min-Hao

    2017-07-01

    The impact fretting wear has largely occurred at nuclear power device induced by the flow-induced vibration, and it will take potential hazards to the service of the equipment. However, the present study focuses on the tangential fretting wear of alloy 690 tubes. Research on impact fretting wear of alloy 690 tubes is limited and the related research is imminent. Therefore, impact fretting wear behavior of alloy 690 tubes against 304 stainless steels is investigated. Deionized water is used to simulate the flow environment of the equipment, and the dry environment is used for comparison. Varied analytical techniques are employed to characterize the wear and tribochemical behavior during impact fretting wear. Characterization results indicate that cracks occur at high impact load in both water and dry equipment; however, the water as a medium can significantly delay the cracking time. The crack propagation behavior shows a jagged shape in the water, but crack extended disorderly in dry equipment because the water changed the stress distribution and retarded the friction heat during the wear process. The SEM and XPS analysis shows that the main failure mechanisms of the tube under impact fretting are fatigue wear and friction oxidation. The effect of medium(water) on fretting wear is revealed, which plays a potential and promising role in the service of nuclear power device and other flow equipments.

  3. Fretting Wear Behavior of Tin Plated Contacts:. Influence on Contact Resistance

    Science.gov (United States)

    Park, Young Woo; Sankara Narayanan, T. S. N.; Lee, Kang Yong

    The fretting wear behavior of tin plated copper alloy contacts and its influence on the contact resistance are addressed in this paper. Based on the change in the area of contact zone as well as the wear depth as a function of fretting cycles, a model was proposed to explain the observed low and stable contact resistance. The extent of wear of tin coating and the formation of wear debris as a function of fretting cycles were assessed by scanning electron microscopy (SEM). Energy dispersive X-ray line scanning (EDX), X-ray mapping, and EDX spot analysis were employed to characterize the nature of changes that occur at the contact zone. The study reveals that the fretted area increases linearly up to 8000 cycles due to the continuous removal of the tin coating and attains saturation when the fretting path length reaches a maximum. The observed low and stable contact resistance observed up to 8000 cycles is due to the common area of contact which provides an electrically conducting area. Surface analysis by SEM, EDX, and X-ray elemental mapping elucidate the nature of changes that occurred at the contact zone. Based on the change in contact resistance as a function of fretting cycles, the fretting wear and fretting corrosion dominant regimes are proposed. The interdependence of extent of wear and oxidation increases the complexity of the fretting corrosion behavior of tin plated contacts.

  4. Fretting wear behavior of nitrogen implanted Zircaloy-4 alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Zircaloy-4 was implanted with nitrogen at 120keV with various ion doses between 1 × 1013 and 1 × 1014 ions/m2. Fretting wear tests were performed at various cycles and loads under water immersion condition by the fretting simulator, The implanted surfaces were analyzed by Auger electron spectroscopy (AES) and transmission electron microscope(TEM). Micro-hardnees tester measured surface hardness. It is shown that nitrogen imphantation produced Zirconium nitride oxide and high density dislocations in implanted ltyer, surface hardness was enhanced from HK280 for unimplantedspecimen to HK1800 for a total ion dose of 1 × 1014 ions/m2. The nitrogen ion implantation treatment provided significantimprovements in the resistance of fretting damage.

  5. Effect of frequency on fretting wear behavior of Ti/TiN multilayer film on depleted uranium.

    Science.gov (United States)

    Wu, Yan-Ping; Li, Zheng-Yang; Zhu, Sheng-Fa; Lu, Lei; Cai, Zhen-Bing

    2017-01-01

    The Ti/TiN multi-layer film was prepared on the depleted uranium (DU) substrate by cathodic arc ion plating equipment. The character of multi-layer film was studied by SEM, XRD and AES, revealed that the surface was composed of small compact particle and the cross-section had a multi-layer structure. The fretting wear performance under different frequencies was performed by a MFT-6000 machine with a ball-on-plate configuration. The wear morphology was analyzed by white light interferometer, OM and SEM with an EDX. The result shows the Ti/TiN multi-layer film could greatly improve the fretting wear performance compared to the DU substrate. The fretting wear running and damaged behavior are strongly dependent on the film and test frequency. The fretting region of DU substrate and Ti/TiN multi-layer under low test frequency is gross slip. With the increase of test frequency, the fretting region of Ti/TiN multi-layer change from gross slip to mixed fretting, then to partial slip.

  6. Fretting Wear Behavior of Medium Carbon Steel Modified by Low Temperature Gas Multi-component Thermo-chemical Treatment

    Institute of Scientific and Technical Information of China (English)

    LUO Jun; ZHENG Jianfeng; PENG Jinfang; HE Liping; ZHU Minhao

    2010-01-01

    The introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component (such as carbon, nitrogen, sulphur and oxygen, etc) thermo-chemical treatment(LTGMTT) can overcome the brittleness of nitriding process, and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly. However, there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now, which limits the applications of fretting. So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50 (0.48%C) steel prepared by low temperature gas multi-component thermo-chemical treatment (LTGMTT) technology. The fretting wear tests of the modified layer flat specimens and its substrate (LZ50 steel) against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2 μm to 40 μm. Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope(SEM), optical microscope(OM), X-ray diffraction(XRD) and surface profilometer. The experimental results showed that the modified layer with a total thickness of 60 μm was consisted of three parts, i.e., loose layer, compound layer and diffusion layer. Compared with the substrate, the range of the mixed fretting regime(MFR) of the LTGMTT modified layer diminished, and the slip regime(SR) of the modified layer shifted to the direction of smaller displacement amplitude. The coefficient of friction(COF) of the modified layer was lower than that of the substrate in the initial stage. For the modified layer, the damage in partial slip regime(PSR) was very slight. The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination. The modified layer presented better wear

  7. Cold-Sprayed Cu-MoS2 and Its Fretting Wear Behavior

    Science.gov (United States)

    Zhang, Yinyin; Descartes, Sylvie; Vo, Phuong; Chromik, Richard R.

    2016-02-01

    Cu and Cu-MoS2 coatings were fabricated by cold spray, and the fretting wear performance of the two coatings was compared. A mixture (95 wt.% Cu + 5 wt.% MoS2) was used as feedstock for the composite coating. Coatings were sprayed with identical gas flow conditions on the substrates pre-heated to approximately 170 °C. The morphology of coating top surface and polished cross sections was analyzed by scanning electron microscopy (SEM) and light optical microscopy (LOM). The influence of MoS2 on Cu deposition was examined. The local MoS2 concentration within the coating was found to affect the hardness. Fretting tests were carried out at two different normal loads, and the influence of MoS2 on friction and wear was studied. The morphology and elemental compositions of the wear scars and wear debris were observed by SEM and energy dispersive x-ray spectroscopy (EDS), respectively.

  8. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Song [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Wang, Fei [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Liao, Zhenhua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Wang, Qingliang [School of Material Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Liu, Yuhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, Weiqiang, E-mail: weiqliu@hotmail.com [Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2015-10-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~ 500 nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100 N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-θ (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in

  9. Influence of thermal oxidation duration on the microstructure and fretting wear behavior of Ti6Al4V alloy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Song [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liao, Zhenhua [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Liu, Yuhong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Liu, Weiqiang, E-mail: weiqliu@hotmail.com [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Biomechanics and Biotechnology Lab, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)

    2015-06-01

    Thermal oxidation under water oxidizing atmosphere was performed on Ti6Al4V alloy under different durations from 2 h to 8 h. Surface characterizations were performed using X-ray diffractometery (XRD), scanning electron microscopy (SEM), Raman spectroscopy, nanoindentation and nano scratch testing. Fretting wear behaviors of untreated and oxidized samples were also examined. The formed oxide coating mainly included rutile TiO{sub 2} as well as a little alumina. The weight gain with respect to the oxidation duration obeyed the linear oxidation kinetics law. The growth of oxide grains was in inadequate growth state of incomplete scale coverage from 2nd to 4th hour duration, in normal growth state from 4th to 6th hour duration while in excessive growth state of oxide particle agglomeration and surface roughening from 6th to 8th (or more than 8th) hour duration. The coating thickness increased from 5 μm to 12 μm as oxidation duration increased from 2 h to 8 h. The increase in duration also increased surface roughness and nano hardness as well as adhesion strength of the film/substrate for oxidized samples. The nano hardness value was 10.06 ± 2.15 GPa and the critical load of failure during nano scratch testing was 554.3 ± 6.44 mN for 4 h treated sample. The untreated and oxidized samples showed a same fretting running status and fretting regime with a displacement amplitude of 200 μm while revealing different fretting failure mechanisms. It was mainly abrasive and adhesive wear under ploughing force for untreated sample, while a mix of 3-body abrasion by rolling oxide particles and severe plastic deformation under high contact stress between two ceramic materials for the oxidized samples. The oxide coating was not worn out and improved the fretting wear resistance of titanium alloy. - Highlights: • A thickness of 5–12 μm rutile TiO{sub 2} coating formed under different oxidation durations. • Weight gain with respect to oxidation duration obeyed linear

  10. The role of oxidation in the fretting wear process

    Science.gov (United States)

    Bill, R. C.

    1980-01-01

    Fretting experiments were conducted on titanium, a series of Ni-Cr-Al alloys and on some high temperature turbine alloys at room temperature and at elevated temperatures in air and in various inert environments. It was found that, depending on temperature and environment, the fretting behavior of the materials examined could be classified according to four general types of behavior. Briefly, these types of behavior were: (1) the complete absence of oxidation, as in inert environments, generally leading to low rates of fretting wear but high fretting friction; (2) gradual attrition of surface oxide with each fretting stroke, found in these experiments to operate in concert with other dominating mechanisms; (3) rapid oxidation at surface fatigue damage sites, resulting in undermining and rapid disintegration of the load bearing surface; and (4) the formation of coherent, protective oxide film, resulting in low rates of fretting wear. An analytical model predicting conditions favorable to the fourth type of behavior was outlined.

  11. Study on torsional fretting wear behavior of a ball-on-socket contact configuration simulating an artificial cervical disk.

    Science.gov (United States)

    Wang, Song; Wang, Fei; Liao, Zhenhua; Wang, Qingliang; Liu, Yuhong; Liu, Weiqiang

    2015-10-01

    A ball-on-socket contact configuration was designed to simulate an artificial cervical disk in structure. UHMWPE (ultra high molecular weight polyethylene) hot pressed by powders and Ti6Al4V alloy were selected as the material combination of ball and socket. The socket surface was coated by a ~500 nm C-DLC (carbon ion implantation-diamond like carbon) mixed layer to improve its surface nano hardness and wear resistance. The torsional fretting wear behavior of the ball-on-socket model was tested at different angular displacements under 25% bovine serum lubrication with an axial force of 100 N to obtain more realistic results with that in vivo. The fretting running regimes and wear damage characteristics as well as wear mechanisms for both ball and socket were studied based on 2D (two dimension) optical microscope, SEM (scanning electron microscope) and 3D (three dimension) profiles. With the increase of angular displacement amplitude from 1° to 7°, three types of T-θ (Torsional torque-angular displacement amplitude) curves (i.e., linear, elliptical and parallelogram loops) corresponding to running regimes of PSR (partial slip regime), MR (mixed regime) and SR (slip regime) were observed and analyzed. Both the central region and the edge zone of the ball and socket were damaged. The worn surfaces were characterized by wear scratches and wear debris. In addition, more severe wear damage and more wear debris appeared on the central region of the socket at higher angular displacement amplitude. The dominant damage mechanism was a mix of surface scratch, adhesive wear and abrasive wear for the UHMWPE ball while that for the coated socket was abrasive wear by PE particles and some polishing and rolling process on the raised overgrown DLC grains. The frictional kinetic behavior, wear type, damage region and damage mechanism for the ball-on-socket model revealed significant differences with those of a ball-on-flat contact while showing better consistency with that of in

  12. Modeling of Complex Wear Behavior Associated with Grid-to-Rod Fretting in Light Water Nuclear Reactors

    Science.gov (United States)

    Blau, P. J.; Qu, J.; Lu, R.

    2016-09-01

    Fretting wear damage to fuel cladding from flow-induced vibrations can be a significant concern in the operation of light water nuclear reactors. For years, research on the grid-to-rod fretting (GTRF) phenomena has been underway in countries where nuclear power production is a significant industry. Under the auspices of the U.S. Department of Energy Consortium for Advanced Simulation of Light Water Reactors, an effort has been underway to develop and test an engineering wear model for zirconium alloy fuel rod cladding against a supporting grid. The multi-stage model accounts for oxide layers and wear rate transitions. This paper describes the basis for a GTRF engineering wear model, the physical significance of the wear factor it contains, and recent progress toward model validation based on a fretting wear testing apparatus that accounts for coolant temperature, pressure, and the presence of periodic impacts (gaps) in grid/rod contact.

  13. Modeling of Complex Wear Behavior Associated with Grid-to-Rod Fretting in Light Water Nuclear Reactors

    Science.gov (United States)

    Blau, P. J.; Qu, J.; Lu, R.

    2016-11-01

    Fretting wear damage to fuel cladding from flow-induced vibrations can be a significant concern in the operation of light water nuclear reactors. For years, research on the grid-to-rod fretting (GTRF) phenomena has been underway in countries where nuclear power production is a significant industry. Under the auspices of the U.S. Department of Energy Consortium for Advanced Simulation of Light Water Reactors, an effort has been underway to develop and test an engineering wear model for zirconium alloy fuel rod cladding against a supporting grid. The multi-stage model accounts for oxide layers and wear rate transitions. This paper describes the basis for a GTRF engineering wear model, the physical significance of the wear factor it contains, and recent progress toward model validation based on a fretting wear testing apparatus that accounts for coolant temperature, pressure, and the presence of periodic impacts (gaps) in grid/rod contact.

  14. Effects of Plasma ZrN Metallurgy and Shot Peening Duplex Treatment on Fretting Wear and Fretting Fatigue Behavior of Ti6Al4V Alloy

    Directory of Open Access Journals (Sweden)

    Jingang Tang

    2016-03-01

    Full Text Available A metallurgical zirconium nitride (ZrN layer was fabricated using glow metallurgy using nitriding with zirconiuming prior treatment of the Ti6Al4V alloy. The microstructure, composition and microhardness of the corresponding layer were studied. The influence of this treatment on fretting wear (FW and fretting fatigue (FF behavior of the Ti6Al4V alloy was studied. The composite layer consisted of an 8-μm-thick ZrN compound layer and a 50-μm-thick nitrogen-rich Zr–Ti solid solution layer. The surface microhardness of the composite layer is 1775 HK0.1. A gradient in cross-sectional microhardness distribution exists in the layer. The plasma ZrN metallurgical layer improves the FW resistance of the Ti6Al4V alloy, but reduces the base FF resistance. This occurs because the improvement in surface hardness results in lowering of the toughness and increasing in the notch sensitivity. Compared with shot peening treatment, plasma ZrN metallurgy and shot peening composite treatment improves the FW resistance and enhances the FF resistance of the Ti6Al4V alloy. This is attributed to the introduction of a compressive stress field. The combination of toughness, strength, FW resistance and fatigue resistance enhance the FF resistance for titanium alloy.

  15. Effects of Plasma ZrN Metallurgy and Shot Peening Duplex Treatment on Fretting Wear and Fretting Fatigue Behavior of Ti6Al4V Alloy.

    Science.gov (United States)

    Tang, Jingang; Liu, Daoxin; Zhang, Xiaohua; Du, Dongxing; Yu, Shouming

    2016-03-23

    A metallurgical zirconium nitride (ZrN) layer was fabricated using glow metallurgy using nitriding with zirconiuming prior treatment of the Ti6Al4V alloy. The microstructure, composition and microhardness of the corresponding layer were studied. The influence of this treatment on fretting wear (FW) and fretting fatigue (FF) behavior of the Ti6Al4V alloy was studied. The composite layer consisted of an 8-μm-thick ZrN compound layer and a 50-μm-thick nitrogen-rich Zr-Ti solid solution layer. The surface microhardness of the composite layer is 1775 HK0.1. A gradient in cross-sectional microhardness distribution exists in the layer. The plasma ZrN metallurgical layer improves the FW resistance of the Ti6Al4V alloy, but reduces the base FF resistance. This occurs because the improvement in surface hardness results in lowering of the toughness and increasing in the notch sensitivity. Compared with shot peening treatment, plasma ZrN metallurgy and shot peening composite treatment improves the FW resistance and enhances the FF resistance of the Ti6Al4V alloy. This is attributed to the introduction of a compressive stress field. The combination of toughness, strength, FW resistance and fatigue resistance enhance the FF resistance for titanium alloy.

  16. Fretting wear behavior of Cr-coated fuel rod for accident-tolerant fuel in flowing fluid

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young Ho; Kim, Hyung Kyu; Kim, Hyun Gil; Koo, Yang Hyun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Fretting wear test of the Cr-coated fuel clading candidate have been performed in the flowing fluid condition in order to verify the reliability of Cr-coated layer on zirconium-based fuel cladding. Rod wear volume at each grid spring and dimple is dramaically increased with GTR gap even though each wear scar is not evenly distributed within a 1x1 grid cell.

  17. Fretting wear behavior of laser-nitrided Ti-5Al-5Mo-5V-1Cr-1Fe alloy fabricated by laser melting deposition

    Science.gov (United States)

    Liu, L.; Shangguan, Y. J.; Tang, H. B.; Wang, H. M.

    2014-09-01

    Fretting wear behavior of laser-nitrided titanium alloy (Ti-5Al-5Mo-5V-1Cr-1Fe) fabricated by laser melting deposition (LMD) has been investigated to explore surface engineering for protection against wear damage of laser melting deposited titanium alloy. The morphology and volume of the wear scars of unmodified and laser-nitrided LMD Ti-5Al-5Mo-5V-1Cr-1Fe tested at different frequencies, 10 and 50 Hz, were studied using non-contact three-dimensional surface profilometer and scanning electron microscope. Friction coefficients measured at different frequencies or loading forces were compared for unmodified and laser-nitrided LMD specimens. Experimental results show that laser-nitrided LMD specimens have shown fretting resistance superior to unmodified LMD specimens due to the presence of hard TiN dendrites in the laser-nitrided layer. W-shaped wear scar caused by local rotation of fretting ball at the two ends of the scar was observed. Given a constant loading force of 50 N, unmodified and laser-nitrided LMD specimens exhibited similar friction coefficients and their friction coefficients increased with test frequency. The friction coefficients of both specimens increased with the reduction of normal load, which corresponds to the trend in Hertzian contact model.

  18. Influence of Fretting Wear on Lifetime of Tin Plated Connectors

    Science.gov (United States)

    Ikeda, Hirosaka; Ito, Tetsuya; Sawada, Shigeru; Hattori, Yasuhiro; Saitoh, Yasushi; Tamai, Terutaka; Iida, Kazuo

    Due to the recent increase in electronic devices mounted on automobiles, a large number of connectors, especially low-cost tin plated connectors are being used. As a result, their contact reliability has become problematic. Furthermore, for the connectors which are subjected to fretting wear caused by heat cycle and vibrations, the contact resistance increases because of wear of tin and deposition of oxides, which generates problems of poor contact. This study is intended to analyze the change in contact resistance of tin plated connectors from the start of fretting wear to the end of their lifetime from the viewpoint of practical reliability, and to observe the trace and the characteristics of fretting wear microscopically. This study found that wear and oxidation of tin plated connectors start immediately with fretting wear, and thus accumulation of abrasion powder on fretting areas causes connectors to reach to the end of their useful lifetime quickly. Especially, it was demonstrated that amplitude of fretting has a considerable influence on a connector's lifetime. It is made clear that air-tightness, so-called “gas-tight” of tin in a fretting area influences fretting wear considerably.

  19. Sliding Wear and Fretting Wear of DLC-Based, Functionally Graded Nanocomposite Coatings

    Science.gov (United States)

    Miyoshi, K.; Pohlchuck, B.; Street, Kenneth W.; Zabinski, J. S.; Sanders, J. H.; Voevodin, A. a.; Wu, R. L. C.

    1999-01-01

    Improving the tribological functionality of diamondlike carbon (DLC) films--developing, good wear resistance, low friction, and high load-carrying capacity-was the aim of this investigation. Nanocomposite coatings consisting of an amorphous DLC (a-DLC) top layer and a functionally graded titanium-titanium carbon-diamondlike carbon (Ti-Ti(sub x) C(sub y)-DLC) underlayer were produced on AISI 440C stainless steel substrates by the hybrid technique of magnetron sputtering and pulsed-laser deposition. The resultant DLC films were characterized by Raman spectroscopy, scanning electron microscopy, and surface profilometry. Two types of wear experiment were conducted in this investioation: sliding friction experiments and fretting wear experiments. Unidirectional ball-on-disk sliding friction experiments were conducted to examine the wear behavior of an a-DLC/Ti-Ti(sub x) C(sub y)-DLC-coated AISI 440C stainless steel disk in sliding contact with a 6-mm-diameter AISI 440C stainless steel ball in ultrahigh vacuum, dry nitrogen, and humid air. Although the wear rates for both the coating and ball were low in all three environments, the humid air and dry nitrogen caused mild wear with burnishing, in the a-DLC top layer, and the ultrahigh vacuum caused relatively severe wear with brittle fracture in both the a-DLC top layer and the Ti-Ti(sub x) C(sub y)-DLC underlayer. For reference, amorphous hydrogenated carbon (H-DLC) films produced on a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coatings by using an ion beam were also examined in the same manner. The H-DLC films markedly reduced friction even in ultrahigh vacuum without sacrificing wear resistance. The H-DLC films behaved much like the a-DLC/Ti-Ti(sub x) C(sub y)-DLC nanocomposite coating in dry nitrogen and humid air, presenting low friction and low wear. Fretting wear experiments were conducted in humid air (approximately 50% relative humidity) at a frequency of 80 Hz and an amplitude of 75 micron on an a

  20. Titanium carbide nanoparticles reinforcing nickel matrix for improving nanohardness and fretting wear properties in wet conditions

    Science.gov (United States)

    Dănăilă, Eliza; Benea, Lidia; Caron, Nadège; Raquet, Olivier

    2016-09-01

    In this study Ni/nano-TiC functional composite coatings were produced by electro-codeposition of TiC nanoparticles (50 nm mean diameter) with nickel on 304L stainless steel support. Coatings were obtained from a Watts classical solution in which TiC nanoparticles were added. The surface morphology, chemical composition, structure, roughness and thickness, were evaluated in relation to the effect of TiC nanoparticles incorporation into Ni matrix. It was found that incorporation of TiC nanoparticles into the nickel matrix produces morphological changes in the deposit and increases the roughness. The fretting wear behavior in wet conditions of the obtained coatings was evaluated on a ball-on-plate configuration. To evaluate the wet fretting wear (tribocorrosion) behavior the open circuit potential was measured before, during and after the fretting tests at room temperature in the solution that simulates the primary water circuit of Pressurized Water Reactors. The results show that Ni/nano-TiC composite coatings exhibited a low friction coefficient, high nanohardness and fretting wear resistance in wet conditions compared with pure Ni coatings.

  1. Interference Assembly and Fretting Wear Analysis of Hollow Shaft

    Directory of Open Access Journals (Sweden)

    Chuanjun Han

    2014-01-01

    Full Text Available Fretting damage phenomenon often appears in the interference fit assembly. The finite element model of hollow shaft and shaft sleeve was established, and the equivalent stress and contact stress were computed after interference assembly. The assembly body of hollow shaft and shaft sleeve was in whirling bending load, and the contact status (sticking, sliding, and opening and the distribution of stress along one typical contact line were computed under different loads, interferences, hollow degrees, friction coefficient, and wear quantity. Judgment formula of contact state was fixed by introducing the corrected coefficient k. The computation results showed that the “edge effect” appears in the contact surface after interference fit. The size of slip zone is unchanged along with the increase of bending load. The greater the interference value, the bigger the wear range. The hollow degree does not influence the size of stick zone but controls the position of the junction point of slip-open. Tangential contact stress increases with the friction coefficient, which has a little effect on normal contact stress. The relationship between open size and wear capacity is approximately linear.

  2. Fretting wear damage of HexTOOL{sup TM} composite depending on the different fibre orientations

    Energy Technology Data Exchange (ETDEWEB)

    Terekhina, S; Salvia, M; Fouvry, S [Laboratoire de Tribologie et Dynamique des Systemes, UMR CNRS ECL ENISE ENSMSE 5513, Ecole Centrale de Lyon, 69134 Ecully cedex (France); Malysheva, G; Tarasova, T, E-mail: svetlana.terekhina@ec-lyon.fr, E-mail: svetlanaterekhina@yandex.ru [Bauman Moscow State Technical University, 105005 Moscow, 5, 2nd Baumanskaya str (Russian Federation)

    2009-09-15

    The composites have drawn considerable interest in the mould processes. The vibrations and fatigue stresses induced in the moulds made evident to characterize the composite HexTOOL{sup TM} under fretting conditions. Fretting is a small-amplitude oscillatory motion between contacting surfaces. The running conditions fretting maps (RCFM) of composite at ambient conditions were established. The influence of different fiber orientations of HexTOOL{sup TM} composite on the wear kinetics was shown. An energy wear approach was developed. According to results of dynamic mechanical analysis (DMA), the viscoelastic properties of composite material were obtained.

  3. Test Methodology of Reproducing Fuel Rod Failure by Debris Fretting Wear

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Oh Joon; Park, Nam Gyu; Kim, Jae Ik [KEPCO NF, Daejeon (Korea, Republic of)

    2015-10-15

    A test was conducted with simple debris to reproduce debris fretting wear. 68% of fuel rod cladding thickness is worn out by Inconel debris in 75 hours. The test result shows that a simple link system is useful to accommodate debris oscillation, and mid grid mixing vanes could be a source of debris forcing. Additional tests will be conducted with various debris such as wire brush, metal chip, etc which are suspected to generate actual debris fretting wear in future works. Debris fretting is one of the most common cause of the nuclear fuel rod failure. Even the most of the nuclear fuels has debris protection system, debris still cause fuel rod failure. From 1994 to 2006, debris fretting failure is around 11% of the total fuel failure. In 2006-2010, the portion of debris rises to over 13%. The total number of fuel rods failure is decreasing, but the portion of the debris fretting wear is growing with time. Therefore reproducing and identifying the mechanism of fuel rod failure by debris fretting wear is needed to improve reliability of the nuclear fuel.

  4. Friction and Wear Behaviors of Nanostructured Metals

    Institute of Scientific and Technical Information of China (English)

    Zhong HAN; Yusheng ZHANG; Ke LU

    2008-01-01

    Nanostructured (ns) materials, i.e., polycrystalline materials with grain sizes in the nanometer regime (typically below 100 nm), have drawn considerable attention in the past decades due to their unique properties such as high strength and hardness. Wear resistance of ns materials, one of the most important properties for engineering materials, has been extensively investigated in the past decades. Obvious differences have been identified in friction and wear behaviors Between the ns materials and their corresponding coarse-grained (cg) counterparts, consistently correlating with their unique structure characteristics and mechanical properties. On the other hand, the superior tribological properties of ns materials illustrate their potential applications under contact loads. The present overview will summarize the important progresses achieved on friction and wear behaviors of ns metallic materials, including ultrafine-grained (ufg) materials in recent years. Tribological properties and effects on friction and wear behaviors of ns materials will be discussed under different wear conditions including abrasive wear, sliding wear, and fretting wear. Their correlations with mechanical properties will be analyzed. Perspectives on development of this field will be highlighted as well.

  5. Low-Frequency Reciprocating Fretting Wear Testing System Design and Experiment Research

    Institute of Scientific and Technical Information of China (English)

    Zhongnan Wang∗,Wuyi Wang; Guangyu Zhang

    2015-01-01

    The fretting wear is resulted from different or same sample’ s surfaces by the small variationand leads to mechanism failures. The main factors consist of the variation of normal load and oscillation frequencies, among which surface topography of different materials are the main factors to the problems of the fretting wear. Therefore, a novel low⁃frequency reciprocating fretting wear test system is designed upon the principle of Friction coefficient measurement. Four metal and non⁃metallic samples are measured under various normal load and oscillation frequencies to obtain the instantaneous friction coefficient in the repeat experiments. In fact, the experimental results show that CoF curves of different samples with the increase of the normal load are the similar exponential decay or parabolic shapes, which are consistent with the literatures to verify the rational design and reliable⁃operation of the system under the conditions of different frequencies.

  6. Interference Assembly and Fretting Wear Analysis of Hollow Shaft

    OpenAIRE

    Chuanjun Han; Jie Zhang

    2014-01-01

    Fretting damage phenomenon often appears in the interference fit assembly. The finite element model of hollow shaft and shaft sleeve was established, and the equivalent stress and contact stress were computed after interference assembly. The assembly body of hollow shaft and shaft sleeve was in whirling bending load, and the contact status (sticking, sliding, and opening) and the distribution of stress along one typical contact line were computed under different loads, interferences, hollow d...

  7. Design improvement for fretting-wear reduction of HANARO fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yeong Garp; Chae, H. T.; Ryu, J. S.; Kim, H. R

    2000-06-01

    In the course of the visual inspection of the fuel assemblies un-loaded from the reactor core in December 1996, it was observed that many of fuel assemblies had mechanical damages on some components. The major damage was the freting-wear on spacer plates and endplates due to the flow induced vibration of the fuel assembly in the flow tube. Since the reactor is activated and the system modification for complete removal of the driving factors of the vibration of fuel assemblies is practically very difficult, the focus has been on the design change of the fuel assemblies. Consequently, various design changes were proposed to strengthen the wear resistance of the components based on the evaluation of the visual inspection results. The validity of the proposals was verified through the performance tests for the modified components, and the vibration test and endurance test for the fuel assemblies using the single-channel test rig(SCTR) in AECL.The subsequent design changes were additionally proposed based on the visual inspections for the fuel assemblies that had been fabricated according to the first design change and loaded in the core. As the effects of the first design change, the fretting-wear of spacer plates was remarkably reduced and the period until fretting-wear damage was extended by 60% for the first modified 36-rod fuel assembly. It is too early to say the endurance life time for the first modified 18-rod fuel assembly because of insufficient statistical data of only two bundles damaged, but the fretting-wear at the bottom endplate slot was reduced to about 50%. The second modified fuel assemblies, that were not loaded into the core yet, are expected to meet the design requirements for the core residence time due to strengthening the weak parts from the fretting-wear point of view. This report describes design changes and tests for fuel assemblies of HANARO to reduce the fretting-wear, and estimates the effects of design improvement quantitatively compared

  8. A Study on Fretting Wear Property of CVD SiC and Sintered SiC

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Hyun-Jin; Jang, Ki-Nam; An, Ji-Hyeong; Kim, Kyu-Tae [Dongguk University, Gyeongju (Korea, Republic of)

    2015-10-15

    Silicon Carbide is broadly used as high temperature structure material because of its high temperature tolerance and superior mechanical properties. After the Fukushima nuclear power plant accident, SiC proposed as one of the alternative materials for LWR fuel cladding to provide enhanced safety margin. Grid-to-rod fretting wear-induced fuel failure is known to occur due to flow-induced vibration of the reactor core and grid to- rod gap. In this paper, wear tests for CVD SiC plate and sintered SiC tube were performed with two types of spacer grids. Wear test of corroded and non-corroded CVD SiC plates indicate that wear resistance of corroded specimen is lower than one of non-corroded specimen in contrast with zirconium alloy cladding tube. It may be affected by rough surface of corroded specimen caused by grain boundary attack.

  9. Processing, Characterization and Fretting Wear of Zinc Oxide and Silver Nanoparticles Reinforced Ultra High Molecular Weight Polyethylene Biopolymer Nanocomposite

    Science.gov (United States)

    Alam, Fahad; Kumar, Anil; Patel, Anup Kumar; Sharma, Rajeev K.; Balani, Kantesh

    2015-04-01

    Ultra-high molecular weight polyethylene (UHMWPE) is the most widely used biopolymer for articulating surfaces, such as an acetabular cup liner interfacing with a metal/ceramic femoral head. However, the formation of wear debris leads to the aseptic loosening of implants. Thus, in order to improve the life span via enhancing the fretting wear resistance, UHMWPE is reinforced with ZnO/Ag nanoparticles. It is envisaged that the ZnO/Ag addition will also exhibit antibacterial properties. In the current study, the synergetic effect of the reinforcement of ZnO/Ag nanoparticles (0-3 wt.% combinations) on the fretting wear behavior of a UHMWPE matrix is assessed. The phase characterization of compression- molded UHMWPE-Ag-ZnO biopolymer nanocomposites has elicited the retention of starting phases. All samples were processed at >98% density using compression molding. Silver and ZnO reinforcement showed enhanced hardness ~20.4% for U3A and 42.0% for U3Z. Fretting wear performance was evaluated at varying loads (5-15 N), keeping in mind the weight at different joints, with constant frequency (5 Hz) as well as amplitude of oscillation (100 µm). Laser surface profilometry showed change of wear volume from 8.6 × 10-5 mm3 for neat polymer to 5.8 × 10-5 mm3 with 1 wt.% Ag + 1 wt.% ZnO reinforcement (at 15 N load). Consequently, the mechanics of resistance offered by Ag and ZnO is delineated in the UHMWPE matrix. Further, S. aureus viability reduction is ~28.7% in cases with 1 wt.% Ag addition, ~42.5% with 1 wt.% ZnO addition, but synergistically increase to ~58.6% and 47.1% when each of Ag and ZnO is added with 1 wt.% and 3 wt.%, respectively (when compared to that of the UHMWPE control sample). Increased wear resistance and superior bioactivity and enhanced anti-bacterial properties of 1 wt.% Ag + 1 wt.% ZnO and 3 wt.% Ag + 3 wt.% ZnO shows the potential use of ZnO-Ag-UHMWPE biopolymer composites as an articulating surface.

  10. Effects of temperature, slip amplitude, contact pressure on fretting fatigue behavior of Ti811 alloys at elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    Xiaohua ZHANG; Daoxin LIU

    2009-01-01

    Effects of the temperature, slip amplitude, and contact pressure on fretting fatigue (FF) behavior of the Ti811 titanium alloy were investigated using a high frequency fatigue machine and a home-made high temperature apparatus. The fretting fatigue failure mechanism was studied by observing the fretting surface morphology features. The results show that the sensitivity to fretting fatigue is high at both 350 and 500 ℃. The higher the temperature, the more sensitive to the fretting fatigue failure is. Creep is an important factor that influences the fretting fatigue failure process at elevated temperatures. The fretting fatigue life of the Ti811 alloy does not change in a monotonic way as the slip amplitude and contact pressure increase. This is owing to the fact that the slip amplitude affects the action of fatigue and wear in the fretting process, and the nominal contact pressure affects the distribution and concentration of the stress and the amplitude of fretting slip at the contact surface, and thus further influences the crack initiation probability and the driving force for propagation.

  11. An all-in-one numerical methodology for fretting wear and fatigue life assessment

    Directory of Open Access Journals (Sweden)

    I. Llavori

    2016-07-01

    Full Text Available Many mechanical components such as, bearing housings, flexible couplings and spines or orthopedic devices are simultaneously subjected to a fretting wear and fatigue damage. For this reason, the combined study on a single model of wear, crack initiation and propagation is of great interest. This paper presents an all-in-one 2D cylinder on flat numerical model for life assessment on coupled fretting wear and fatigue phenomena. In the literature, two stages are usually distinguished: crack nucleation and its subsequent growth. The method combines the Archard wear model, a critical-plane implementation of the Smith-Watson- Topper (SWT multiaxial fatigue criterion coupled with the Miner-Palmgren accumulation damage rule for crack initiation prediction. Then, the Linear Elastic Fracture Mechanics (LEFM via eXtended Finite Element Method (X-FEM embedded into the commercial finite element code Abaqus FEA has been employed to determine the crack propagation stage. Therefore, the sum of the two stages gives a total life prediction. Finally, the numerical model was validated with experimental data reported in the literature and a good agreement was obtained.

  12. The effect of plasma nitriding and post oxidation on fretting wear behaviour of a high strength alloy steel

    Science.gov (United States)

    Prakash, N. Arun; Bennett, C. J.

    2017-05-01

    The fretting wear performance of the non-nitrided, nitrided and nitrided-post oxidized high strength alloy steel, W460 were investigated in the gross slip regime at ambient condition. Fretting wear tests were performed with an applied normal load of 250 and 650 N at a displacement amplitude of 100 μm using a cylinder-on-flat configuration. X-ray analysis (XRD) revealed the formation of the iron-nitrided Fe3N and Fe4N during plasma nitriding and iron oxide phases of hematite (Fe2O3) and magnetite (Fe3O4) during post-oxidation of the cylindrical steel samples. The steady state tangential force coefficient decreases when the nitrided and post-oxidized samples were fretted against the non-nitrided steel material when compared to the non-nitrided steel contact pair. The steady state tangential force coefficient decreased with an increase in applied normal load across all of the fretting conditions. The total dissipated energy and the total wear volume increased with an increase in applied normal load with total wear volume of the non-nitrided vs nitrided and non-nitrided vs nitrided post-oxidized sample pairs, showing a reduction in the wear volume of approximately 50% compared to the non-nitrided vs non-nitrided combination under the fretting conditions examined. The worn surface morphology of the fretted samples examined using a scanning electron microscope showed the presence of loose wear debris in the wear track, fragmented wear debris, delamination cracks, delamination with large discontinuities, plate-like wear debris, oxide patches and formation of large cavities.

  13. Advanced non-linear flow-induced vibration and fretting-wear analysis capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Toorani, M.; Pan, L.; Li, R.; Idvorian, N. [Babcock and Wilcox Canada Ltd., Cambridge, Ontario (Canada); Vincent, B.

    2009-07-01

    Fretting wear is a potentially significant degradation mechanism in nuclear steam generators and other shell and tube heat transfer equipment as well. This paper presents an overview of the recently developed code FIVDYNA which is used for the non-linear flow-induced vibration and fretting wear analysis for operating steam generators (OTSG and RSG) and shell-and-tube heat exchangers. FIVDYNA is a non-linear time-history Flow-Induced Vibration (FIV) analysis computer program that has been developed by Babcock and Wilcox Canada to advance the understanding of tube vibration and tube to tube-support interaction. In addition to the dynamic fluid induced forces the program takes into account other tube static forces due to axial and lateral tube preload and thermal interaction loads. The program is capable of predicting the location where the fretting wear is most likely to occur and its magnitude taking into account the support geometry including gaps. FIVDYNA uses the general purpose finite element computer code ABAQUS as its solver. Using ABAQUS gives the user the flexibility to add additional forces to the tube ranging from tube preloads and the support offsets to thermal loads. The forces currently being modeled in FIVDYNA are the random turbulence, steady drag force, fluid-elastic forces, support offset and pre-strain force (axial loads). This program models the vibration of tubes and calculates the structural dynamic characteristics, and interaction forces between the tube and the tube supports. These interaction forces are then used to calculate the work rate at the support and eventually the predicted depth of wear scar on the tube. A very good agreement is found with experiments and also other computer codes. (author)

  14. Friction and wear properties of high-velocity oxygen fuel sprayed WC-17Co coating under rotational fretting conditions

    Science.gov (United States)

    Luo, Jun; Cai, Zhenbing; Mo, Jiliang; Peng, Jinfang; Zhu, Minhao

    2016-05-01

    Rotational fretting which exist in many engineering applications has incurred enormous economic loss. Thus, accessible methods are urgently needed to alleviate or eliminate damage by rotational fretting. Surface engineering is an effective approach that is successfully adopted to enhance the ability of components to resist the fretting damage. In this paper, using a high-velocity oxygen fuel sprayed (HVOF) technique WC-17Co coating is deposited on an LZ50 steel surface to study its properties through Vickers hardness testing, scanning electric microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffractrometry (XRD). Rotational fretting wear tests are conducted under normal load varied from 10 N to 50 N, and angular displacement amplitudes vary from 0.125° to 1°. Wear scars are examined using SEM, EDX, optical microscopy (OM), and surface topography. The experimental results reveal that the WC-17Co coating adjusted the boundary between the partial slip regime (PSR) and the slip regime (SR) to the direction of smaller amplitude displacement. As a result, the coefficients of friction are consistently lower than the substrate's coefficients of friction both in the PSR and SR. The damage to the coating in the PSR is very slight. In the SR, the coating exhibits higher debris removal efficiency and load-carrying capacity. The bulge is not found for the coating due to the coating's higher hardness to restrain plastic flow. This research could provide experimental bases for promoting industrial application of WC-17Co coating in prevention of rotational fretting wear.

  15. Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains.

    Directory of Open Access Journals (Sweden)

    Jie Min

    Full Text Available The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains.Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated.The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes.Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings.

  16. Fretting damage behavior and mechanism of tin coated zircaloy-4 tube

    Institute of Scientific and Technical Information of China (English)

    Tae-HyungKim; Ji-HyunSung; Seock-SamKim

    2001-01-01

    The fretting characteristics of TiN coated Zircaloy-4 tube were investigated experimen-tally. The fretting experiment was performed using TIN coated Zircaloy-4 tube as the fuel rod clad-ding material and uncoated Zircaloy-4 tube as one of grids. TIN coating is probably one of the mostfrequently and successfully used PVD coatings for the mitigation of fretting. In this study, TiN coat-ing by PVD was employed for improvement of Zircaloy-4 tube fretting characteristics. The frettingtester was designed and manufactured for this experiment. The number of cycles, slip amplitudeand normal load were selected as main factors of fretting. The results of this research showed thatthe wear volume of TiN coated Zircaloy-4 tube increased as number of cycles, normal load andslip amplitude increase but the quantity of volume was lower than the case of uncoated Zircaloy-4tube pairs.

  17. Fretting wear in titanium, Monel-400, and cobalt 25-percent-molybdenum using scanning electron microscopy

    Science.gov (United States)

    Bill, R. C.

    1972-01-01

    Damage scar volume measurements taken from like metal fretting pairs combined with scanning electron microscopy observations showed that three sequentially operating mechanisms result in the fretting of titanium, Monel-400, and cobalt - 25-percent molybdenum. Initially, adhesion and plastic deformation of the surface played an important role. This was followed after a few hundred cycles by a fatigue mechanism which produced spall-like pits in the damage scar. Finally, a combination of oxidation and abrasion by debris particles became most significant. Damage scar measurements made on several elemental metals after 600,000 fretting cycles suggested that the ratio of oxide hardness to metal hardness was a measure of the susceptibility of a metal to progressive damage by fretting.

  18. Dual Time Stepping Algorithms With the High Order Harmonic Balance Method for Contact Interfaces With Fretting-Wear

    CERN Document Server

    Salles, Loic; Gouskov, Alexandre; Jean, Pierrick; Thouverez, Fabrice

    2014-01-01

    Contact interfaces with dry friction are frequently used in turbomachinery. Dry friction damping produced by the sliding surfaces of these interfaces reduces the amplitude of bladed-disk vibration. The relative displacements at these interfaces lead to fretting-wear which reduces the average life expectancy of the structure. Frequency response functions are calculated numerically by using the multi-harmonic balance method (mHBM). The dynamic Lagrangian frequency-time method is used to calculate contact forces in the frequency domain. A new strategy for solving nonlinear systems based on dual time stepping is applied. This method is faster than using Newton solvers. It was used successfully for solving Nonlinear CFD equations in the frequency domain. This new approach allows identifying the steady state of worn systems by integrating wear rate equations a on dual time scale. The dual time equations are integrated by an implicit scheme. Of the different orders tested, the first order scheme provided the best re...

  19. Wear behavior of austenite containing plate steels

    Science.gov (United States)

    Hensley, Christina E.

    As a follow up to Wolfram's Master of Science thesis, samples from the prior work were further investigated. Samples from four steel alloys were selected for investigation, namely AR400F, 9260, Hadfield, and 301 Stainless steels. AR400F is martensitic while the Hadfield and 301 stainless steels are austenitic. The 9260 exhibited a variety of hardness levels and retained austenite contents, achieved by heat treatments, including quench and tempering (Q&T) and quench and partitioning (Q&P). Samples worn by three wear tests, namely Dry Sand/Rubber Wheel (DSRW), impeller tumbler impact abrasion, and Bond abrasion, were examined by optical profilometry. The wear behaviors observed in topography maps were compared to the same in scanning electron microscopy micrographs and both were used to characterize the wear surfaces. Optical profilometry showed that the scratching abrasion present on the wear surface transitioned to gouging abrasion as impact conditions increased (i.e. from DSRW to impeller to Bond abrasion). Optical profilometry roughness measurements were also compared to sample hardness as well as normalized volume loss (NVL) results for each of the three wear tests. The steels displayed a relationship between roughness measurements and observed wear rates for all three categories of wear testing. Nanoindentation was used to investigate local hardness changes adjacent to the wear surface. DSRW samples generally did not exhibit significant work hardening. The austenitic materials exhibited significant hardening under the high impact conditions of the Bond abrasion wear test. Hardening in the Q&P materials was less pronounced. The Q&T microstructures also demonstrated some hardening. Scratch testing was performed on samples at three different loads, as a more systematic approach to determining the scratching abrasion behavior. Wear rates and scratch hardness were calculated from scratch testing results. Certain similarities between wear behavior in scratch testing

  20. Effects of Contact Load on the Fretting Fatigue Behavior of IN-100 at Elevated Temperature

    Science.gov (United States)

    2009-03-01

    experimental setup which did not accurately model the turbine engine environment. Kawagoishi et al. [23] studied the nickel-based alloy Inconel 718 ...In their study with Inconel 718 [48, 49], it was found that the beneficial glaze oxide had formed and did affect the fretting fatigue life. Their...Waterhouse [52] investigated the fretting fatigue behaviors of austenitic steel type 321 and nickel-based alloy Inconel 718 at elevated temperatures. He

  1. The roles of contact conformity, temperature and displacement amplitude on the lubricated fretting wear of a steel-on-steel contact

    Science.gov (United States)

    Warmuth, A. R.; Sun, W.; Shipway, P. H.

    2016-10-01

    This paper investigates the effect of contact geometry, temperature and displacement amplitude on the fretting behaviour of an aero-turbo oil lubricated cylinder-on-flat contact. To be effective, the lubricant needed both to penetrate the contact and then offer protection. Lubricant penetration into the fretting contact is found to be controlled by two physical parameters, namely (i) the width of the contact that remains covered throughout the fretting test and (ii) the lubricant viscosity. The protection offered by the lubricant (assuming that it has successfully penetrated the contact) is influenced by four physical parameters, namely (i) lubricant viscosity, (ii) traverse velocity, (iii) nominal contact pressure, and (iv) chemical effects. The relationship between the three experimental parameters which were varied in the programme of work (temperature, fretting displacement and cylinder radius) and physical parameters which influence the protection offered by the lubricant film can be competing, and therefore complex wear behaviour is observed. The roles of the various parameters in controlling the wear behaviour are presented in a coherent physical framework.

  2. Fretting Fatigue Behavior of Shot-Peened IN 100

    Science.gov (United States)

    2006-03-01

    117 - x - List of Figures Figure Page Figure 1. Blade/ Disc ...Blade/ Disc Dovetail Joint in a Turbine Engine. - 7 - Figure 2. Simplified Fretting Configuration Contact Load (P) Fatigue Specimen (P...steam turbine power plants, medical applications, nuclear power systems, and in the chemical petrochemical industries 28. Nickel superalloys are

  3. Standard guide for fretting fatigue testing

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This guide defines terminology and covers general requirements for conducting fretting fatigue tests and reporting the results. It describes the general types of fretting fatigue tests and provides some suggestions on developing and conducting fretting fatigue test programs. 1.2 Fretting fatigue tests are designed to determine the effects of mechanical and environmental parameters on the fretting fatigue behavior of metallic materials. This guide is not intended to establish preference of one apparatus or specimen design over others, but will establish guidelines for adherence in the design, calibration, and use of fretting fatigue apparatus and recommend the means to collect, record, and reporting of the data. 1.3 The number of cycles to form a fretting fatigue crack is dependent on both the material of the fatigue specimen and fretting pad, the geometry of contact between the two, and the method by which the loading and displacement are imposed. Similar to wear behavior of materials, it is important t...

  4. Effects of the different frequencies and loads of ultrasonic surface rolling on surface mechanical properties and fretting wear resistance of HIP Ti-6Al-4V alloy

    Science.gov (United States)

    Li, G.; Qu, S. G.; Pan, Y. X.; Li, X. Q.

    2016-12-01

    The main purpose of this paper was to investigate the effects of the different frequencies and loads of multi-pass ultrasonic surface rolling (MUSR) on surface layer mechanical properties, microstructure and fretting friction and wear characteristics of HIP (hot isostatic pressing) Ti-6Al-4 V alloy. Some microscopic analysis methods (SEM, TEM and EDS) were used to characterize the modified surface layer of material after MUSR treatment. The results indicated that the material in sample surface layer experienced a certain extent plastic deformation, and accompanied by some dense dislocations and twins generation. Moreover surface microhardness and residual stress of samples treated by MUSR were also greatly improved compared with the untreated. The fretting friction and wear properties of samples treated by MUSR in different conditions are tested at 10 and 15 N in dry friction conditions. It could be found that friction coefficient and wear volume loss were significantly declined in the optimal result. The main wear mechanism of MUSR-treated samples included abrasive wear, adhesion and spalling.

  5. Impact wear behaviors of Hadfield manganese steel

    Institute of Scientific and Technical Information of China (English)

    FANG Liang; XU Yun-hua; CEN Qi-hong; ZHU Jin-hua

    2005-01-01

    Impact wear behaviors of Hadfield manganese steel at different impact angles were investigated. The results of impact wear tests show that there exists a critical impact load for Hadfield steel. The wear rate suddenly turns down after some impact cycles when the impact load is greater than the critical load. The critical impact load is smaller than 8.2 J in this research because the nano-sized austenitic grains embedded in amorphous delay the crack propagation in subsurface. From high resolution transmission electron microscope (HRTEM) examination of subsurface microstructure, it is found that a large amount of nano-sized grains embedded in bulk amorphous matrix are fully developed and no martensitic transformation occurs during the impact wear process. The analytical results of worn surface morphology and debris indicate that the initiation of crack, propagation and spalling are restricted in the amorphous phase, resulting in the size distribution of debris in nano-sizes, which is the reason why the wear rate of Hadfield steel is greatly decreased at high impact load.

  6. Fretting of AISI 9310 and selected fretting resistant surface treatments

    Science.gov (United States)

    Bill, R. C.

    1977-01-01

    Fretting wear experiments were conducted with uncoated AISI 9310 mating surfaces, and with combinations incorporating a selected coating to one of the mating surfaces. Wear measurements and SEM observations indicated that surface fatigue, as made evident by spallation and surface crack formation, is an important mechanism in promoting fretting wear to uncoated 9310. Increasing humidity resulted in accelerated fretting, and a very noticeable difference in nature of the fretting debris. Of the coatings evaluated, aluminum bronze with a polyester additive was most effective at reducing wear and minimizing fretting damage to the mating uncoated surface, by means of a selflubricating film that developed on the fretting surfaces. Chromium plate performed as an effective protective coating, itself resisting fretting and not accelerating damage to the uncoated surface.

  7. Fretting Fatigue Behavior of Nickel Alloy IN-100

    Science.gov (United States)

    2006-03-01

    K., B. F. Dyson, and M. McLean. “Tension-Compression Creep Asym- metry In a Turbine Disc Superalloy : Roles of Internal Stress and Thermal Age- ing...understand the fretting phenomenon and its mechanisms, but only a few have been performed on nickel-based alloys. This superalloy is considered one...excellent magnetic properties, but only at low magnetic induction. Nowadays, the need for the use of high-strength nickel-based superalloys in

  8. Fretting fatigue behavior of high-strength steel monostrands under bending load

    DEFF Research Database (Denmark)

    Winkler, Jan; Georgakis, Christos T.; Fischer, Gregor

    2015-01-01

    In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. To measure the local deformations on the strands, a novel method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires...... along the length of the monostrand. Information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of a monostrand undergoing flexural deformations is provided. From the series of dynamic fatigue tests, a fretting fatigue spectrum is derived...

  9. Effect of equal channel angular extrusion on wear and corrosion behavior of the orthopedic Ti-13Nb-13Zr alloy in simulated body fluid

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, K.S. [Department of Materials. Engineering, Indian Institute of Science, Bangalore 560012 (India); Geetha, M., E-mail: geethamanivasagam@vit.ac.in [School of Mechanical and Building Sciences, VIT University, Vellore (India); Richard, C. [Laboratoire de Mecanique et de Rheologie EA 2640, Polytech' Tours, 37000 Tours (France); Landoulsi, J. [Laboratoire de Reactivite de Surface, UMR 7197 CNRS, Universite Pierre and Marie Curie - Paris VI, 4 Place Jussieu, Case 178, F-75252 Paris (France); Ramasawmy, H. [University of Mauritius, Faculty of Engineering, Reduit (Mauritius); Suwas, S. [Department of Materials. Engineering, Indian Institute of Science, Bangalore 560012 (India); Asokamani, R. [School of Mechanical and Building Sciences, VIT University, Vellore (India)

    2012-05-01

    We report investigations on the texture, corrosion and wear behavior of ultra-fine grained (UFG) Ti-13Nb-Zr alloy, processed by equal channel angular extrusion (ECAE) technique, for biomedical applications. The microstructure obtained was characterized by X-ray line profile analysis, scanning electron microscope (SEM) and electron back scattered diffraction (EBSD). We focus on the corrosion resistance and the fretting behavior, the main considerations for such biomaterials, in simulated body fluid. To this end, potentiodynamic polarization tests were carried out to evaluate the corrosion behavior of the UFG alloy in Hanks solution at 37 Degree-Sign C. The fretting wear behavior was carried out against bearing steel in the same conditions. The roughness of the samples was also measured to examine the effect of topography on the wear behavior of the samples. Our results showed that the ECAE process increases noticeably the performance of the alloy as orthopedic implant. Although no significant difference was observed in the fretting wear behavior, the corrosion resistance of the UFG alloy was found to be higher than the non-treated material. Highlights: Black-Right-Pointing-Pointer Relevancy of ECAE process applied to titanium alloy for biomedical applications. Black-Right-Pointing-Pointer Significant improvement of mechanical properties of the surface. Black-Right-Pointing-Pointer Noticeable increase of the corrosion resistance in simulated body fluid.

  10. Study of fretting wear in titanium, Monel-400, and cobalt-25 percent molybdenum using scanning electron microscopy.

    Science.gov (United States)

    Bill, R. C.

    1973-01-01

    Damage scar volume measurements taken from like metal fretting pairs, combined with scanning electron microscopy observations, showed that three sequentially operating mechanisms result in the fretting of titanium, Monel-400, and cobalt-25% molybdenum. Initially, adhesion and plastic deformation on the surface played an important role. This was followed after a few hundred cycles by a fatigue mechanism, producing spall-like pits in the damage scar. Finally, an oxidation-related mechanism became most significant. Damage scar measurements made on several elemental metals after 600,000 fretting cycles suggested that the ratio of oxide hardness to metal hardness was a measure of the susceptibility of a metal to progressive damage by fretting.

  11. Study of fretting wear in titanium, Monel-400, and cobalt-25 percent molybdenum using scanning electron microscopy.

    Science.gov (United States)

    Bill, R. C.

    1973-01-01

    Damage scar volume measurements taken from like metal fretting pairs, combined with scanning electron microscopy observations, showed that three sequentially operating mechanisms result in the fretting of titanium, Monel-400, and cobalt-25% molybdenum. Initially, adhesion and plastic deformation on the surface played an important role. This was followed after a few hundred cycles by a fatigue mechanism, producing spall-like pits in the damage scar. Finally, an oxidation-related mechanism became most significant. Damage scar measurements made on several elemental metals after 600,000 fretting cycles suggested that the ratio of oxide hardness to metal hardness was a measure of the susceptibility of a metal to progressive damage by fretting.

  12. Fretting wear behaviour of hydroxyapatite-titanium composites in simulated body fluid, supplemented with 5 g l-1 bovine serum albumin

    Science.gov (United States)

    Kumar, Alok; Biswas, Krishanu; Basu, Bikramjit

    2013-10-01

    Damaged articulating joints can be repaired or replaced with synthetic biomaterials, which can release wear debris due to articulation, leading to the osteolysis. In a recent work, it has been shown that it is possible to achieve a better combination of flexural strength/fracture toughness as well as in vitro bioactivity and cytocompatibility properties in spark plasma sintered hydroxyapatite-titanium (HA-Ti) composites. Although hydroxyapatite and titanium are well documented for their good biocompatibility, nanosized hydroxyapatite (HA) and titanium (Ti) particles can cause severe toxicity to cells. In order to address this issue, fretting wear study of HA-Ti composites under dry and wet (1× SBF, supplemented with 5 g l-1 bovine serum albumin (BSA)) condition was performed to assess the wear resistance as well as wear debris formation, in vitro. The experimental results reveal one order of magnitude lower wear rate for HA-10 wt% Ti (7.5 × 10-5 mm3 N-1 m-1) composite than monolithic HA (3.9 × 10-4 mm3 N-1 m-1) in simulated body fluid. The difference in the tribological properties has been analyzed in the light of phase assemblages and mechanical properties. Overall, the results suggest the potential use of HA-Ti composites over existing HA-based biocomposites in orthopedic as well as dental applications.

  13. Experimental and Numerical Investigations of Fretting Fatigue Behavior for Steel Q235 Single-Lap Bolted Joints

    Directory of Open Access Journals (Sweden)

    Yazhou Xu

    2016-01-01

    Full Text Available This work aims to investigate the fretting fatigue life and failure mode of steel Q235B plates in single-lap bolted joints. Ten specimens were prepared and tested to fit the S-N curve. SEM (scanning electron microscope was then employed to observe fatigue crack surfaces and identify crack initiation, crack propagation, and transient fracture zones. Moreover, a FEM model was established to simulate the stress and displacement fields. The normal contact stress, tangential contact stress, and relative slipping displacement at the critical fretting zone were used to calculate FFD values and assess fretting fatigue crack initiation sites, which were in good agreement with SEM observations. Experimental results confirmed the fretting fatigue failure mode for these specimens. It was found that the crack initiation resulted from wear regions at the contact surfaces between plates, and fretting fatigue cracks occurred at a certain distance away from hole edges. The proposed FFD-N relationship is an alternative approach to evaluate fretting fatigue life of steel plates in bolted joints.

  14. Microstructural aspects and wear behavior of sinter hardened distaloy HP

    Energy Technology Data Exchange (ETDEWEB)

    Sheikhi Moghaddam, K.; Ghambari, M.; Farhangi, H. [School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran (Iran, Islamic Republic of); Solimanjad, N.; Bergmark, A. [Hoeganaes AB, Bruksgatan, Hoeganaes (Sweden); Khorsand, H. [K.N. Toosi University, Tehran (Iran, Islamic Republic of)

    2011-11-15

    Effect of cooling rate during sinter hardening on the microstructure and wear behavior of sintered steel grade Distaloy HP has been studied. Wear performances are closely related to macro and micro hardness of the materials. Dry sliding wear tests have been conducted using a reciprocating pin on flat wear testing machine under normal loads of 25, 35 and 45N and at a constant speed of 0.3 m/s. The samples were sinter hardened at different cooling rates 0.5-3 C/s in order to investigate the influence of microstructure and hardness on wear behavior. It has been shown that, sintering process and cooling rate change the microstructure and hence the hardness and wear behavior of the material. The best wear resistance was detected at a cooling rate of 3 C/s. At this cooling rate the material had an almost martensitic microstructure and the wear rate was some how independent of the applied load. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Wear Behavior of an Unstable Knee: Stabilization via Implant Design?

    Directory of Open Access Journals (Sweden)

    Jörn Reinders

    2014-01-01

    Full Text Available Background. Wear-related failures and instabilities are frequent failure mechanisms of total knee replacements. High-conforming designs may provide additional stability for the joint. This study analyzes the effects of a ligamentous insufficiency on the stability and the wear behavior of a high-conforming knee design. Methods. Two simulator wear tests were performed on a high-conforming total knee replacement design. In the first, a ligamentous-stable knee replacement with a sacrificed anterior cruciate ligament was simulated. In the second, a ligamentous-unstable knee with additionally insufficient posterior cruciate ligament and medial collateral ligament was simulated. Wear was determined gravimetrically and wear particles were analyzed. Implant kinematics was recorded during simulation. Results. Significantly higher wear rates (P≤0.001 were observed for the unstable knee (14.58±0.56 mg/106 cycles compared to the stable knee (7.97 ± 0.87 mg/106 cycles. A higher number of wear particles with only small differences in wear particle characteristics were observed. Under unstable knee conditions, kinematics increased significantly for translations and rotations (P≤0.01. This increase was mainly attributed to higher tibial posterior translation and internal rotations. Conclusion. Higher kinematics under unstable test conditions is a result of insufficient stabilization via implant design. Due to the higher kinematics, increased wear was observed in this study.

  16. Experimental evaluation of the fretting fatigue behavior of high-strength steel monostrands

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.

    2013-01-01

    . Moreover, the paper provides relevant information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of the monostrand undergoing flexural deformations. The results presented herein are of special interest for the fatigue analysis of modern stay......In this paper, the fretting fatigue behavior of pretensioned high-strength steel monostrands is investigated. A method based on the digital image correlation (DIC) technique was used to quantify the relative movement between individual wires along the length of the monostrand. The experimental data...

  17. Wear and Friction Behavior of Metal Impregnated Microporous Carbon Composites

    Science.gov (United States)

    Goller, Gultekin; Koty, D. P.; Tewari, S. N.; Singh, M.; Tekin, A.

    1996-01-01

    Metal-matrix composites have been prepared by pressure-infiltration casting of copper-base alloy melts into microporous carbon preforms. The carbon preforms contained varying proportions of amorphous carbon and graphite. Load dependence of the wear and friction behavior of the composite pins has been examined under ambient conditions against cast-iron plates, using a pin-on-plate reciprocating wear tester. The wear resistance of the composite is significantly improved, as compared with the base alloy. Contrary to the normally expected behavior, the addition of graphite to the amorphous carbon does not reduce the friction coefficient, especially at high loads. The wear and friction behavior of the composites is very sensitive to the size and distribution of the microstructural constituents.

  18. Predicting bicycle helmet wearing intentions and behavior among adolescents.

    Science.gov (United States)

    O'Callaghan, Frances V; Nausbaum, Sarah

    2006-01-01

    Cycling accidents in Australia, especially those resulting in head injuries, are a substantive cause of death and disability; but despite legislation and evidence that helmets reduce the risk of head injury, few adolescents wear them. This study employed a revised version of the Theory of Planned Behavior (TPB; [Ajzen, I. (1991). The theory of planned behavior. Organizational Behavior and Human Decision Processes, 50, 179-211]) to investigate the determinants of helmet use among a sample of adolescents. Participants in the initial data collection were 294 high school students in Year 8 and Year 11, with 266 completing a follow-up questionnaire measuring behavior over the previous two weeks. Social norms, perceptions of control, and past behavior significantly predicted intentions to use helmets and perceptions of control and past behavior predicted actual helmet use. Strengthening the routine of helmet use and building young people's confidence that they can overcome any perceived barriers to helmet use will improve adherence to helmet wearing behavior.

  19. Development of the vibration analysis technique of fuel rod and research on the methodology of fuel fretting wear analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Heung Seok; Kim, Kyung Kyu; Yoon, Hyung Hoo; Song, Ki Nam

    1998-12-01

    The FEM program has been developed to predict the natural frequencies, the FEM program has been developed to predict the natural frequencies, and mode shapes of fuel rod subjected to axial force and continuously supported by a rotational and vent spring system, and to calculate the minimum reaction forces of the spacer grid spring when the maximum vibration amplitude of fuel rod is known. This program has been verified by commercial ANSYS program and the vibration test of dummy rods in air. The test equipment were set to get the fifth modes of test rods. Partial slip problem has been studied for the analysis of fuel fretting problem. Firstly, the assumption of semi-infiniteness of the contact bodies were validated by finite element (FE) analysis. From FE results, a classical bodies were validated by finite element (FE) analysis. From FE results, aclassical theory of elasticity was utilized with regarding the problem as a plane problem. Secondly, the Mindlin-Cattaneo problem was re-evaluated, which gave the fundamental idea for developing the numerical tool for the shear traction on the contact. Shear force of sequentially-changing directions was considered and the corresponding shear traction was evaluated by extending the numerical tool for the Mindlin-Cattaneo problem.

  20. Fretting Fatigue Experiment and Analysis of AlSi9Cu2Mg Alloy

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2016-12-01

    Full Text Available An investigation was carried out in order to study the fretting fatigue behavior of an AlSi9Cu2Mg aluminum alloy. The fretting fatigue tests of AlSi9Cu2Mg were performed using a specially designed testing machine. The failure mechanism of fretting fatigue was explored by studying the fracture surfaces, fretting scars, fretting debris, and micro-hardness of fretting fatigue specimens using scanning electron microscopy (SEM, energy-dispersive X-ray spectroscopy (EDX, and micro Vickers hardness test techniques. The experimental results show that the fretting fatigue limit (42 MPa is significantly reduced to approximately 47% of the plain fatigue limit (89 MPa under 62.5 MPa contact pressure. Furthermore, the fretting fatigue life decreases with increasing alternating stress and increasing contact pressure. The examination results suggest that the stress concentrates induced by oxidation-assisted wear on the contact interface led to the earlier initiation and propagation of crack under the fretting condition.

  1. Corrosive wear behavior of 2014 and 6061 aluminum alloy composites

    Energy Technology Data Exchange (ETDEWEB)

    Varma, S.K.; Andrews, S.; Vasquez, G. [Univ. of Texas, El Paso, TX (United States). Dept. of Metallurgical and Materials Engineering

    1999-02-01

    Alloys of 2014 and 6061 aluminum reinforced with 0.1 volume fraction of alumina particles (VFAP) were subjected to impact scratching during a corrosive wear process. The transient currents generated due to the impact were measured in the two composites as well as in their respective monoliths. The effect of solutionizing time on the transient currents was correlated to the near surface microstructures, scratch morphology, concentration of quenched-in vacancies, and changes in grain sizes. It was observed that the transient current values increase with an increase in solutionizing time, indicating that the corrosive wear behavior is not strongly affected by the grain boundaries. However, a combination of pitting and the galvanic corrosion may account for the typical corrosive wear behavior exhibited by the alloys and the composites of this study.

  2. On the Friction and Wear Behaviors of Dental Machinable Porcelain

    Institute of Scientific and Technical Information of China (English)

    YU Hai-yang; ZHOU Zhong-rong; CAI Zhen-Bing

    2004-01-01

    In order to well design tribosystems of dental CAD-CAM restorations, an understanding of the tribological mechanisms of dental machinable porcelain are essential. The friction and wear behavior of new generation industrially prefabricated Cerec Vitablocs Mark Ⅱ against uniform Si3N4 ball has been performed using a small amplitude reciprocating apparatus under simulating oral conditions. The loads of 10-40 N, reciprocating amplitudes of 100-500 μm, frequencies of 1-4 Hz and two lubrications (no / artificial saliva lubrication) were selected. Tests lasting up to 10 000 cycles were conducted. The results show that Cerec Vitablocs Mark Ⅱ record a friction coefficient of 0.55-0.84. Artificial saliva plays a lubricant effect during wear process. Among three parameters of the test on friction coefficient and wear depth of dental machinable porcelains, the load effect is prominent. Abrasive wear is the main wear mechanism, but brittle cracks and delamination are more popular especially under unlubricated friction.

  3. On the Friction and Wear Behaviors of Dental Machinable Porcelain

    Institute of Scientific and Technical Information of China (English)

    YUHai-yang; ZHOUZhong-rong; CAIZhen-Bing

    2004-01-01

    In order to well design tribosystems of dental CAD-CAM restorations, an understanding of the tribological mechanisms of dental machinable porcelain are essential. The friction and wear behavior of new generation industrially prefabricated Cerec Vitablocs Mark II against uniform Si3N4ball has been performed using a small amplitude reciprocating apparatus under simulating oral conditions. The loads of 10-40N, reciprocating amplitudes of 100-500μm, frequencies of 1-4Hz and two lubrications (no / artificial saliva lubrication) were selected. Tests lasting up to 10 000 cycles were conducted. The results show that Cerec Vitablocs Mark Ⅱ record a friction coefficient of 0.55-0.84. Artificial saliva plays a lubricant effect during wear process. Among three parameters of the test on friction coefficient and wear depth of dental machinable porcelains, the load effect is prominent. Abrasive wear is the main wear mechanism, but brittle cracks and delamination are more popular especially under unlubricated friction.

  4. The Effect of Elevated Temperature on the Fretting Fatigue Behavior of Nickel Alloy IN-100

    Science.gov (United States)

    2008-04-01

    Saladin S-N data points for plain fatigue 86 4.16 Comparison of Ownby and Saladin S-N data points for fretting fatigue 87 4.17 Comparison of Ownby...and Saladin S-N data for all tests 88 4.18 Plot comparing ΔQ vs Nf from Ownby, Saladin & Madhi data points 89 4.19 Plot from Kawagoishi et al. [21...in this study 93 4.3 Madhi fretting and plain fatigue testing data 94 4.4 Saladin fretting and plain fatigue testing data 94 4.5 Comparison of

  5. Dry wear behaviors of wear resistant composite coatings produced by laser cladding

    Institute of Scientific and Technical Information of China (English)

    Jiang Xu; Wenjin Liu; Minlin Zhong

    2004-01-01

    Using different proportional mixtures of Ni-coated MoS2, TiC and pure Ni powders, new typical wear resistant and selflubricant coatings were formed on low carbon steel by laser cladding process. The microstructures and phase composition of the composite coatings were studied by SEM and XRD. The typical microstructure of the composite coating is composed of multisulfide phases including binary element sulfide and ternary element sulfide, γ-Ni, TiC and Mo2C. Wear tests were carried out using an FALEX-6 type pin-on-disc machine. The friction coefficient and mass loss of three kinds of MoS2/TiC/Ni laser clad coatings are lower than those of quenched 45 steel, and the worn surfaces of the laser cladding coatings are very smooth. Because of high hardness combined with low friction, the laser cladding composite coating with a mixture of 70% Ni-coated MoS2, 20%TiC and 10%pure Ni powder presents better wear behaviors than the composite coating with other powder blends. The composition analysis of the worn surface of GCr15 bearing steel shows that the transferred film from the laser cladding coating to the opposite surface of GCr15beating steel contains an amount of sulfide, which can change the micro-friction mechanism and lead to a reduced friction coefficient.

  6. Fretting Behavior of SPR Joining Dissimilar Sheets of Titanium and Copper Alloys

    Directory of Open Access Journals (Sweden)

    Xiaocong He

    2016-12-01

    Full Text Available The fretting performance of self-piercing riveting joining dissimilar sheets in TA1 titanium alloy and H62 copper alloy was studied in this paper. Load-controlled cyclic fatigue tests were carried out using a sine waveform and in tension-tension mode. Scanning electron microscopy and energy-dispersive X-ray techniques were employed to analyze the fretting failure mechanisms of the joints. The experimental results showed that there was extremely severe fretting at the contact interfaces of rivet and sheet materials for the joints at relatively high loads levels. Moreover, the severe fretting in the region on the locked sheet in contact with the rivet was the major cause of the broken locked sheet for the joints at low load level.

  7. Fretting properties of biodegradable Mg-Nd-Zn-Zr alloy in air and in Hank's solution.

    Science.gov (United States)

    Li, Wenting; Li, Nan; Zheng, Yufeng; Yuan, Guangyin

    2016-11-04

    Fretting is a significant cause for the failure of orthopedic implants. Currently, since magnesium and its alloys have been developed as promising biodegradable implant materials, the fretting behavior of the Mg alloys is of great research significance. In this study, a Mg-Nd-Zn-Zr alloy (hereafter, denoted as JDBM alloy) was selected as experimental material, and its fretting behaviors were evaluated under 5 N, 10 N and 20 N normal loads with a displacement of 200 μm under the frequency of 10 Hz at 37 °C in air and in Hank's solution, respectively. The results indicated that while the friction coefficient decreased with the increment of the normal load, the wear volume of the alloy increased with the increment of the normal load both in air and in Hank's solution. Both the friction coefficients and the wear volume of the fretting in Hank's solution were much lower than those in air environment. The evolution trend of friction coefficients with time had different performance in air environment and the Hank's solution group. Although oxidation occurred during the fretting tests in Hank's solution, the damage of JDBM alloy was still reduced due to the lubrication effects of Hank's solution. Moreover, the addition of Fetal bovine serum (FBS) could act as lubrication and result in the reduction of the fretting damage.

  8. Nanocomposite TiSiBC Hard Coatings with High Resistance to Wear, Fracture and Scratching

    Science.gov (United States)

    Mahato, P.; Nyati, G.; Singh, R. J.; Mishra, S. K.

    2016-09-01

    The sliding wear under fretting condition, scratch adhesion, deformation behavior during micro- and nanoscratch studies have been studied for nanocomposite TiSiBC hard coating deposited on steel substrate by magnetron sputtering. The nanocomposite coatings having hardness and modulus around 30 and 300 GPa, respectively, showed a very significant decrease in fretting wear as compared to the uncoated steel. Pileup occurred along the sides of the scratch track due to plastic deformation of the substrate at the scratch load; however, cracks were not seen in films. The coefficient of friction remained scratch, higher wear resistance, higher toughness and low coefficient of friction.

  9. Abrasive Wear Behavior of High Chromium Cast Iron and Hadfield Steel-- A Comparison

    Institute of Scientific and Technical Information of China (English)

    Mehdi Mazar Atabaki; Sajjad Jafari; Hassan Abdollah-pour

    2012-01-01

    Wear properties of two different crushers used for grinding raw materials of cement industry are compared using pin-on-disk wear test.The wear test was carried out with different loads on a pin.Abrasive wear behavior of two alloys was evaluated by comparing mass loss,wear resistance,microhardness and friction coefficient.The microstructure of the specimens was detected using optical microscope.The results showed that abrasive wear of high chromium cast iron is lower than that of Hadfield steel.Due to the presence of M7C3 carbides on the high chromium cast iron matrix,impact crushers exhibited higher friction coefficient

  10. EXPERIMENTAL INVESTIGTION OF THE FRETTING PHENOMENON

    Directory of Open Access Journals (Sweden)

    Ştefan GHIMISI

    2015-12-01

    Full Text Available Fretting is now fully identified as a small amplitude oscilatory motion which induces a harmonic tangential force between two surfaces in contact.It is related to three main loadings, i.e. fretting-wear, fretting-fatigue and fretting corrosion.Fretting regimes were first mapped by Vingsbo. In a similar way, three fretting regimes will be considered: stick regime,slip regime and mixed regime. The mixed regime was made up of initial gross slip followed by partial slip condition after a few hundred cycles. Obviously the partial slip transition develops the highest stress levels which can induce fatigue crack nucleation depending on the fatigue properties of the two contacting first bodies. Therefore prediction of the frontier between partial slip and gross slip is required.

  11. Fretting corrosion behavior of nitinol spinal rods in conjunction with titanium pedicle screws.

    Science.gov (United States)

    Lukina, Elena; Kollerov, Mikhail; Meswania, Jay; Khon, Alla; Panin, Pavel; Blunn, Gordon W

    2017-03-01

    Untypical corrosion damage including erosions combined with the build-up of titanium oxide as a corrosion product on the surface of explanted Nitinol spinal rods in the areas where it was in contact with titanium pedicle screw head is reported. It was suggested that Nitinol rods might have inferior fretting corrosion resistance compared with that made of titanium or CoCr. Fretting corrosion of Nitinol spinal rods with titanium (Ti6Al4V) pedicle screws were tested in-vitro by conducting a series of potentiostatic measurements of the peak-to-peak values of fretting corrosion current under bending in a 10% solution of calf serum in PBS. The test included Nitinol rods locked in titanium pedicle screws of different designs. Performance of commercially available titanium (Ti6Al4V) and CoCr spinal rods was also investigated for a comparison. Corrosion damage observed after the in-vitro tests was studied using SEM and EDAX analysis and was compared with patterns on Nitinol rods retrieved 12months after initial surgery. Metal ions level was measured in the test media after in-vitro experiments and in the blood and tissues of the patients who had the rods explanted. The results of this study revealed that Nitinol spinal rods locked in Ti pedicle screws are susceptible to fretting corrosion demonstrating higher fretting corrosion current compared with commercially used Ti6Al4V and CoCr rods. On the surface of Nitinol rods after in-vitro tests and on those retrieved from the patients similar corrosion patterns were observed. Improved resistance to fretting corrosion was observed with Nitinol rods in the in-vitro tests where pedicle screws were used with a stiffer locking mechanism. Since the development of the localized corrosion damage might increase the risk of premature fatigue failure of the rods and result in leaching of Ni ions, it is concluded that Nitinol rods should not be used in conjunction with Ti pedicle screws without special protection especially where the

  12. Effects of Nitriding and Laser Quenching on Fretting Wear Resistance of 18Cr2Ni4WA Steel%氮化激光淬火复合处理对18Cr2Ni4WA钢抗微动磨损性能的影响

    Institute of Scientific and Technical Information of China (English)

    李助军; 陈泽宇; 陈选民; 周欢伟

    2011-01-01

    Fretting wear resistance of 18Cr2Ni4WA steel with nitriding and laser quenching was studied on a SRV Ⅳ oscillating friction and wear tester.The results show that the hardness of sample after nitriding and laser quenching is about 780 HV, and the sample has excellent fretting wear resistance.The main fretting wear mechanism is abrasive wear and adhesion wear.%在SRVⅣ微动磨损试验机上考察了氮化激光复合处理和正火+高温回火处理对18Cr2Ni4WA钢抗微动磨损性能的影响.结果表明:在试验条件下,渗氮激光复合处理试样的维氏硬度约为780 HV,具有较好的抗微动磨损性能.磨损机理主要为粘着磨损和磨粒磨损.

  13. Sliding Wear and Friction Behavior of Fuel Rod Material in Water and Dry State

    Science.gov (United States)

    Park, Jin Moo; Kim, Jae Hoon; Jeon, Kyeong Lak; Park, Jun Kyu

    In water cooled reactors, the friction between spacer grid and fuel rod can lead to severe wear and it is an important topic to study. In the present study, sliding wear behavior of zirconium alloy was investigated in water and dry state using the pin-on-disc sliding wear tester. Sliding wear resistance of zirconium alloy against heat treated inconel alloy was examined at room temperature. The parameters in this study were sliding velocity, axial load and sliding distance. The wear characteristics of zirconium alloy was evaluated by friction coefficient, specific wear rate and wear volume. The micro-mechanisms responsible for wear in zirconium alloy were identified to be micro-cutting, micro-pitting, delamination and micro-cracking of deformed surface zone.

  14. Fretting properties of biodegradable Mg-Nd-Zn-Zr alloy in air and in Hank’s solution

    Science.gov (United States)

    Li, Wenting; Li, Nan; Zheng, Yufeng; Yuan, Guangyin

    2016-11-01

    Fretting is a significant cause for the failure of orthopedic implants. Currently, since magnesium and its alloys have been developed as promising biodegradable implant materials, the fretting behavior of the Mg alloys is of great research significance. In this study, a Mg-Nd-Zn-Zr alloy (hereafter, denoted as JDBM alloy) was selected as experimental material, and its fretting behaviors were evaluated under 5 N, 10 N and 20 N normal loads with a displacement of 200 μm under the frequency of 10 Hz at 37 °C in air and in Hank’s solution, respectively. The results indicated that while the friction coefficient decreased with the increment of the normal load, the wear volume of the alloy increased with the increment of the normal load both in air and in Hank’s solution. Both the friction coefficients and the wear volume of the fretting in Hank’s solution were much lower than those in air environment. The evolution trend of friction coefficients with time had different performance in air environment and the Hank’s solution group. Although oxidation occurred during the fretting tests in Hank’s solution, the damage of JDBM alloy was still reduced due to the lubrication effects of Hank’s solution. Moreover, the addition of Fetal bovine serum (FBS) could act as lubrication and result in the reduction of the fretting damage.

  15. Tribological behavior and wear mechanism of resin-matrix contact strip against copper with electrical current

    Institute of Scientific and Technical Information of China (English)

    TU Chuan-jun; CHEN Zhen-hua; CHEN Ding; YAN Hong-ge; HE Feng-yi

    2008-01-01

    The resin-matrix pantograph contact strip (RMPCS), which has excellent abrasion resistance with electrical current and friction-reducing function, was developed in view of the traditional contact strips with high maintenance cost, high wear rate with electrical current and severe damage to the copper conducting wire. The characteristics of worn surfaces, cross-section and typical elemental distributions of RMPCS were studied by scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS).The wear behavior and arc discharge of RMPCS against copper were investigated with self-made electrical wear tester. The results show that the electrical current plays a critical role in determining the wear behavior, and the wear rate of the RMPCS against copper with electrical current is 2.7-5.8 times higher than the value without electrical current. The wear rate of the contact strip increases with the increase of the sliding speed and electrical current density. The main wear mechanism of RMPCS against copper without electrical current is low stress grain abrasive and slightly adhesive wear, while arc erosion wear and oxidation wear are the dominate mechanism with electrical current, which is accompanied by adhesive wear during the process of wear.

  16. Coupling behavior between adhesive and abrasive wear mechanism of aero-hydraulic spool valves

    Institute of Scientific and Technical Information of China (English)

    Chen Yunxia; Gong Wenjun; Kang Rui

    2016-01-01

    Leakage due to wear is one of the main failure modes of aero-hydraulic spool valves. This paper established a practical coupling wear model for aero-hydraulic spool valves based on dynamic system modelling theory. Firstly, the experiment for wear mechanism verification proved that adhesive wear and abrasive wear did coexist during the working process of spool valves. Sec-ondly coupling behavior of each wear mechanism was characterized by analyzing actual time-variation of model parameters during wear evolution process. Meanwhile, Archard model and three-body abrasive wear model were utilized for adhesive wear and abrasive wear, respectively. Furthermore, their coupling wear model was established by calculating the actual wear volume. Finally, from the result of formal test, all the required parameters for our model were obtained. The relative error between model prediction and data of pre-test was also presented to verify the accuracy of model, which demonstrated that our model was useful for providing accurate prediction of spool valve’s wear life.

  17. An Investigation into the Behavior of Disc Blake Wear

    Directory of Open Access Journals (Sweden)

    Muneer A. H.Jassim

    2007-01-01

    Full Text Available A real method of predication brake pad wear ,could lead to substantiol economies of time and money. This paper describes how such a procedure has been used and gives the results to establish is reliability by comparing the predicted wear with that which actually occurs in an existing service. The experimental work was carried out on three different commercial samples ,tested under different operation conditions (speed,load,time...etcusing a test ring especially modified for this purpose. Abrasive wear is mainly studied , since it is the type of wear that takes place in such arrangements. Samples wear tested in presences of sand or mud between the mating surfaces under different operational conditions of speed, load and braking time .Mechanical properties of the pad material samples (hardness, young,s modulus and collapse load under pure bending condition wear established . The thermal conductivity and surface roughness of the pad material wear also found in order to enable comparison between the surface condition before and after testing. Sliding velocity had a small effect on the wear rate but it had great effect on friction coefficient. Wear rate was affected mainly by the surface temperature which causing a reduction friction coefficient and increasing the wear rate. Surface roughness had almost no effect on the wear rate since it was proved experimentally ,that the surface becomes softer during operation .mechanical properties of the pad material had fluctuating effect on wear rate. The existence of solid particles between pad and disc increasing wear rate and friction coefficient while the mud caused a reduction in wear rate of the pad surface since it acts as a lubricant absorbing the surface heat generated during sliding the area of contact between pad and disc. wear rate obtained experimentally agreed fairly well that found from empirically obtained equations.

  18. Experimental Study of the Hygrothermal Effect on Wear Behavior of Composite Materials

    Directory of Open Access Journals (Sweden)

    Fadhel Abbas. Abdulla

    2017-07-01

    Full Text Available The hygrothermal effect on the wear behavior of composite material (fiberglass and polyester resin vf=40% was investigated experimentally in this work. The study includes manufacturing of test device (pin on disc according to ASTM G 99. In order to study the hygrothermal effect on wear behavior of composite materials the hygrothermal chamber was manufactured. The experimental results show that the wear of glass fiber/polyester increased with increasing the load, sliding speed and sliding distance. The load and sliding distance were more effective on the wear of the composite rather than sliding speed. Also, it has been revealed that, the hygrothermal is considerable effect that, the wear rate of glass fiber/polyester without hygrothermal effect is lower than wear with hygrothermal effect. Applied load is the wear factor that has the highest physical influence on the wear of composites materials than other wear factors. Also, the wear of glass fiber/polyester without hygrothermal effect is lower than wear with hygrothermal effect.

  19. Influence of applied load on wear behavior of C/C-Cu composites under electric current

    Directory of Open Access Journals (Sweden)

    Jian Yin

    2017-04-01

    Full Text Available Using carbon fiber needled fabrics with Cu-mesh and graphite powder as the preform, Cu mesh modified carbon/carbon(C/C-Cu composites were prepared by chemical vapor deposition (CVD with C3H6 and impregnation-carbonization (I/C with furan resin. C/C composites, as a comparison, were also prepared. Their microstructures and wear morphologies were observed by optical microscopy (OM and scanning electron microscope (SEM, respectively. Wear behavior of C/C and C/C-Cu composites under different applied loads were investigated on a pin-on-disc wear tester. The results show that Cu meshes are well dispersed and pyrolytic carbon is in rough laminar structure. Both C/C and C/C-Cu composites had good wear properties. The current-carrying capacity of C/C-Cu composites increases and the arc discharge is hindered as the applied load increases from 40 N to 80 N. Both C/C and C/C-Cu composites had good wear properties. The mass wear rate of C/C-Cu composites under 80 N was only 4.2% of that under 60 N. In addition, C/C-Cu composites represent different wear behaviors because wear mechanisms of arc erosion, abrasive wear, adhesive wear, and oxidative wear are changing under different applied loads.

  20. Friction and Wear Behavior of GCr15 Under Multiple Movement Condition

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Friction and wear of GCr15 under cross-sliding condition is tested on a ball-on-disc wear test machine. This result shows that the cross-sliding of friction pair leads to different friction and wear behavior. For the condition described in this paper, the friction coefficients with ball reciprocating are smaller than that without ball reciprocating. The friction coefficients increase with the increase of reciprocating frequency.. The wear weight loss of the ball subjected reciprocating sliding decreases, however, the wear weight loss of disc against the reciprocating ball increases. In cross-sliding friction, the worn surfaces of the ball show crinkle appearance along the circumferential sliding traces. Delaminating of small strip debris is formed along the plowing traces on the disc worn surface. The plowing furrow on the disc surfaces looks deeper and wider than that without reciprocating sliding. The size of wear particles from cross-sliding wear is larger than those without reciprocating sliding.

  1. Sliding wear and friction behavior of zirconium alloy with heat-treated Inconel718

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.H., E-mail: kimjhoon@cnu.ac.kr [Dept. of Mechanical Design Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Park, J.M. [Dept. of Mechanical Design Engineering, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 305-764 (Korea, Republic of); Park, J.K.; Jeon, K.L. [Nuclear Fuel Technology Department, Korea Nuclear Fuel, 1047 Daedukdae-ro, Yuseong-gu, Daejeon 305-353 (Korea, Republic of)

    2014-04-01

    In water-cooled nuclear reactors, the sliding of fuel rod can lead to severe wear and it is an important issue to sustain the structural integrity of nuclear reactor. In the present study, sliding wear behavior of zirconium alloy in dry and water environment using Pin-On-Disk sliding wear tester was investigated. Wear resistance of zirconium alloy against heat-treated Inconel718 pin was examined at room temperature. Sliding wear tests were carried out at different sliding distance, axial load and sliding speed based on ASTM (G99-05). The results of these experiments were verified with specific wear rate and coefficient of friction. The micro-mechanisms responsible for wear in zirconium alloy were identified to be microcutting and microcracking in dry environment. Moreover, micropitting and delamination were observed in water environment.

  2. WearSense: Detecting Autism Stereotypic Behaviors through Smartwatches.

    Science.gov (United States)

    Amiri, Amir Mohammad; Peltier, Nicholas; Goldberg, Cody; Sun, Yan; Nathan, Anoo; Hiremath, Shivayogi V; Mankodiya, Kunal

    2017-02-28

    Autism is a complex developmental disorder that affects approximately 1 in 68 children (according to the recent survey conducted by the Centers for Disease Control and Prevention-CDC) in the U.S., and has become the fastest growing category of special education. Each student with autism comes with her or his own unique needs and an array of behaviors and habits that can be severe and which interfere with everyday tasks. Autism is associated with intellectual disability, impairments in social skills, and physical health issues such as sleep and abdominal disturbances. We have designed an Internet-of-Things (IoT) framework named WearSense that leverages the sensing capabilities of modern smartwatches to detect stereotypic behaviors in children with autism. In this work, we present a study that used the inbuilt accelerometer of a smartwatch to detect three behaviors, including hand flapping, painting, and sibbing that are commonly observed in children with autism. In this feasibility study, we recruited 14 subjects to record the accelerometer data from the smartwatch worn on the wrist. The processing part extracts 34 different features in each dimension of the three-axis accelerometer, resulting in 102 features. Using and comparing various classification techniques revealed that an ensemble of 40 decision trees has the best accuracy of around 94.6%. This accuracy shows the quality of the data collected from the smartwatch and feature extraction methods used in this study. The recognition of these behaviors by using a smartwatch would be helpful in monitoring individuals with autistic behaviors, since the smartwatch can send the data to the cloud for comprehensive analysis and also to help parents, caregivers, and clinicians make informed decisions.

  3. WearSense: Detecting Autism Stereotypic Behaviors through Smartwatches

    Directory of Open Access Journals (Sweden)

    Amir Mohammad Amiri

    2017-02-01

    Full Text Available Autism is a complex developmental disorder that affects approximately 1 in 68 children (according to the recent survey conducted by the Centers for Disease Control and Prevention—CDC in the U.S., and has become the fastest growing category of special education. Each student with autism comes with her or his own unique needs and an array of behaviors and habits that can be severe and which interfere with everyday tasks. Autism is associated with intellectual disability, impairments in social skills, and physical health issues such as sleep and abdominal disturbances. We have designed an Internet-of-Things (IoT framework named WearSense that leverages the sensing capabilities of modern smartwatches to detect stereotypic behaviors in children with autism. In this work, we present a study that used the inbuilt accelerometer of a smartwatch to detect three behaviors, including hand flapping, painting, and sibbing that are commonly observed in children with autism. In this feasibility study, we recruited 14 subjects to record the accelerometer data from the smartwatch worn on the wrist. The processing part extracts 34 different features in each dimension of the three-axis accelerometer, resulting in 102 features. Using and comparing various classification techniques revealed that an ensemble of 40 decision trees has the best accuracy of around 94.6%. This accuracy shows the quality of the data collected from the smartwatch and feature extraction methods used in this study. The recognition of these behaviors by using a smartwatch would be helpful in monitoring individuals with autistic behaviors, since the smartwatch can send the data to the cloud for comprehensive analysis and also to help parents, caregivers, and clinicians make informed decisions.

  4. WearSense: Detecting Autism Stereotypic Behaviors through Smartwatches

    Science.gov (United States)

    Amiri, Amir Mohammad; Peltier, Nicholas; Goldberg, Cody; Sun, Yan; Nathan, Anoo; Hiremath, Shivayogi V.; Mankodiya, Kunal

    2017-01-01

    Autism is a complex developmental disorder that affects approximately 1 in 68 children (according to the recent survey conducted by the Centers for Disease Control and Prevention—CDC) in the U.S., and has become the fastest growing category of special education. Each student with autism comes with her or his own unique needs and an array of behaviors and habits that can be severe and which interfere with everyday tasks. Autism is associated with intellectual disability, impairments in social skills, and physical health issues such as sleep and abdominal disturbances. We have designed an Internet-of-Things (IoT) framework named WearSense that leverages the sensing capabilities of modern smartwatches to detect stereotypic behaviors in children with autism. In this work, we present a study that used the inbuilt accelerometer of a smartwatch to detect three behaviors, including hand flapping, painting, and sibbing that are commonly observed in children with autism. In this feasibility study, we recruited 14 subjects to record the accelerometer data from the smartwatch worn on the wrist. The processing part extracts 34 different features in each dimension of the three-axis accelerometer, resulting in 102 features. Using and comparing various classification techniques revealed that an ensemble of 40 decision trees has the best accuracy of around 94.6%. This accuracy shows the quality of the data collected from the smartwatch and feature extraction methods used in this study. The recognition of these behaviors by using a smartwatch would be helpful in monitoring individuals with autistic behaviors, since the smartwatch can send the data to the cloud for comprehensive analysis and also to help parents, caregivers, and clinicians make informed decisions. PMID:28264474

  5. Investigation of austenitizing temperature on wear behavior of austempered gray iron (AGI)

    Science.gov (United States)

    Sarkar, T.; Sutradhara, G.

    2016-09-01

    This study is about finding the effect of austenitizing temperature on microstructure and wear behavior of copper alloyed austempered gray iron (AGI), and then comparing it with an as- cast (solidified) state. Tensile and wear tests specimens are prepared from as-cast gray iron material, and austenitized at different temperatures and then austempered at a fixed austempering temperature. Resulting microstructures are characterized through optical microscopy, scanning electron microscope (SEM) and X-Ray diffraction. Wear test is carried out using a block-on-roller multi-tribotester with sliding speed of 1.86 m/sec. In this investigation, wear behavior of all these austempered materials are determined and co-related with the micro structure. Hence the wear surface under scanning electron microscope showed that wear occurred mainly due to adhesion and delamination under dry sliding condition. The test results indicate that the austenitizing temperature has remarkable effect on resultant micro structure and wear behavior of austempered materials. Wear behavior is also found to be dependent on the hardness, tensile strength, austenite content and carbon content in austenite. It is shown that coarse ausferrite micro structure exhibited higher wear depth than fine ausferrite microstructure.

  6. Fretting Fatigue of Gamma TiAl Studied

    Science.gov (United States)

    Miyoshi, Kazuhisa; Lerch, Bradley A.; Draper, Susan L.

    2003-01-01

    Gamma titanium-aluminum alloy (g-TiAl) is an attractive new material for aerospace applications because of its low density and high specific strength in comparison to currently used titanium and nickel-base alloys. Potential applications for this material are compressor and low-pressure turbine blades. These blades are fitted into either the compressor or turbine disks via a dovetail connection. The dovetail region experiences a complex stress state due to the alternating centrifugal force and the natural high-frequency vibration of the blade. Because of the dovetail configuration and the complex stress state, fretting is often a problem in this area. Furthermore, the local stress state becomes more complex when the influence of the metal-metal contact and the edge of the contact is evaluated. Titanium and titanium-based alloys in the clean state exhibit strong adhesive bonds when in contact with themselves and other materials (refs. 1 and 2). This adhesion causes heavy surface damage and high friction in practical cases. Although the wear produced by fretting may be mild, the reduction in fatigue life can be substantial. Thus, there is the potential for fretting problems with these TiAl applications. Since TiAl is an emerging material, there has been limited information about its fretting behavior.

  7. Fundamental studies on dynamic wear behavior of SBR rubber compounds modified by SBR rubber powder

    OpenAIRE

    Euchler, Eric; Heinrich, Gert; Michael, Hannes; Gehde, Michael; Stocek, Radek; Kratina, Ondrej; Kipscholl, Reinhold; Bunzel, Jörg-Michael; Saal, Wolfgang

    2016-01-01

    The aim of this study is focused on the experimental investigation of dynamic wear behavior of carbon black filled rubber compounds comprising pristine styrene butadiene rubber (SBR) together with incorporated SBR ground rubber (rubber powder). We also analyzed and described quantitatively the service conditions of some dynamically loaded rubber products, which are liable to wear (e.g. conveyor belts, tires). Beside the well-known standard test method to characterize wear resistance at steady...

  8. Research on Wear Behavior of ATC Cermet Material

    Institute of Scientific and Technical Information of China (English)

    ZHULiu; LINGGuo-ping; LIJian; WANGYou-wen

    2004-01-01

    By electroless chemical deposition process, a layer of metal cobalt film was coated on the surface of nano-ceramic powders of Al2O3 and TiC. The mixture of the two kinds of Co-coated power (about 70wt.% Al2O3-Co+30wt.%TiC-Co) was hot-pressed into ATC (Al2O3-TiC-Co8wt% ) cermet samples. The wear test was carried out under dry sliding wear condition by the pin-on-disk rig. The volume-loss of the samples in three sliding pairs, ATC/Steel, ATC/SiC and ATC/artificial diamond (AD) were investigated. The wear morphologies were examined by SEM. The wear-resistance between ATC cermet and Co-cemented WC were compared. The results show that the effect of fracture toughness is better than that of hardness to the wear resistance of high hardness materials. The wear mechanisms of ATC cermet samples were found that abrasion predominated in the wear process. The wear surface of ATC cermet samples became smoother with fine asperities spalling off and the volume loss was decreased.

  9. Research on Wear Behavior of ATC Cermet Material

    Institute of Scientific and Technical Information of China (English)

    ZHU Liu; LING Guo-ping; LI Jian; WANG You-wen

    2004-01-01

    By electroless chemical deposition process, a layer of metal cobalt film was coated on the surface of nano-ceramic powders of Al203 and TiC. The mixture of the two kinds of Co-coated power (about 70wt.%Al2O3-Co+30wt.%TiC-Co) was hot-pressed into ATC (Al2O3-TiC-Co8wt%) cermet samples. The wear test was carried out under dry sliding wear condition by the pin-on-disk rig. The volume-loss of the samples in three sliding pairs,ATC/Steel, ATC/SiC and ATC/artificial diamond (AD) were investigated. The wear morphologies were examined by SEM.The wear-resistance between ATC cermet and Co-cemented WC were compared. The results show that the effect of fracture toughness is better than that of hardness to the wear resistance of high hardness materials. The wear mechanisms of ATC cermet samples were found that abrasion predominated in the wear process. The wear surface of ATC cermet samples became smoother with fine asperities spalling off and the volume loss was decreased.

  10. Effects of Process Conditions on Fretting Wear Properties of Thermal Sprayed NiCr/WC Nanostructured Coating%喷涂工艺参数对热喷涂纳米镍铬碳化钨涂层微动磨损性能的影响

    Institute of Scientific and Technical Information of China (English)

    刘胜林; 郑雪萍

    2012-01-01

    以纳米NiCr/WC复合粉末(其中70%的WC与30%的NiCr)(文中含量均为质量分数)为原料,采用活性燃烧超音速火焰喷涂技术制备了纳米NiCr/WC复合涂层.利用SRV高温磨损试验机进行微动磨损试验,结果显示,在其它工艺参数相同的条件下,纳米涂层在喷涂距离为200 mm条件下的耐磨性能最差,在喷涂距离为160 mm条件下的耐磨性能最好;纳米涂层在送粉率为5 rpm条件下的耐磨性能最差,在送粉率为15 rpm条件下的耐磨性能最好.此外,与综合性能优良的渗碳轴承钢20CrNi2Mo相比,所有的纳米涂层的耐磨损性能都明显优于相同温度条件下的轴承钢的耐磨损性能.%Nanostructured coatings of NiCr/WC (70% WC, 30%NiCr) were prepared via actived-combustion-high velocity air fuel (AC-HVAF). Fretting wear test was carried out by SRV high, temperature wearing equipment The results show that the thermal sprayed NiCr/WC nanostructured coating prepared from the spraying distance of 160 mm has the best fretting wear properties under the same other process parameters, and the nanostructured coating prepared from the spraying distance of 200 mm has the worst fretting wear properties. The nanostructured coating prepared at the powder feed rate of 15 rpm has the best fretting wear properties under the same other process parameters, the nanostructured coating prepared at the powder feed rate of 5 rpm has the worst fretting wear properties, respectively. In addition, compared to the carburizing bearing steel 20CrNi2Mo with excellent overall performance, the wearing resistances of all nanostructured coatings are better than that of the carburizing bearing steel under the same wear conditions.

  11. Does a micro-grooved trunnion stem surface finish improve fixation and reduce fretting wear at the taper junction of total hip replacements? A finite element evaluation.

    Science.gov (United States)

    Ashkanfar, Ariyan; Langton, David J; Joyce, Thomas J

    2017-08-10

    The generation of particulate debris at the taper junction of total hip replacements (THRs), can cause failure of the artificial hip. The taper surfaces of femoral heads and trunnions of femoral stems are generally machined to a certain roughness to enhance fixation. However, the effect of the surface roughness of these surfaces on the fixation, wear and consequently clinical outcomes of the design is largely unknown. In this study, we asked whether a micro-grooved trunnion surface finish (1) improves the fixation and (2) reduces the wear rate at the taper junction of THRs. We used 3D finite element (FE) models of THRs to, firstly, investigate the effect of initial fixation of a Cobalt-Chromium femoral head with a smooth taper surface mated with a Titanium (1) micro-grooved and (2) smooth, trunnion surface finishes. Secondly, we used a computational FE wear model to compare the wear evolution between the models, which was then validated against wear measurements of the taper surface of explanted femoral heads. The fixation at the taper junction was found to be better for the smooth couplings. Over a 7 million load cycle analysis in-silico, the linear wear depth and the total material loss was around 3.2 and 1.4 times higher for the femoral heads mated with micro-grooved trunnions. It was therefore concluded that smooth taper and trunnion surfaces will provide better fixation at the taper junction and reduce the volumetric wear rates. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. The Wear Behavior of HVOF Sprayed Near-Nanostructured WC-17%Ni(80/20)Cr Coatings in Dry and Slurry Wear Conditions

    Science.gov (United States)

    Ben Mahmud, Tarek A.; Atieh, Anas M.; Khan, Tahir I.

    2017-07-01

    The ability to deposit nanostructured feedstock by using high-velocity oxygen-fuel (HVOF) spray offers potential improvements in coating hardness, wear resistance and toughness for applications in the oil sands industry. In this study, the wear behavior of a near-nanostructured coating was compared under dry and slurry abrasive wear test using an uncoated AISI-1018 low-carbon steel substrate as a reference. The coating microstructures were analyzed in the as-sprayed, dry and slurry test conditions using scanning electron microscopy, x-ray diffraction and microhardness measurements. Wear behavior of the steel and coating surfaces were assessed using a pin-on-plate wear test under various loads. The results showed that a coating could be successfully deposited using the HVOF spraying technique and with retention of the near-nanosized WC dispersion within the coating structure. The wear rate under dry test conditions was greater for the steel and coating compared to tests performed under slurry conditions. Examination of the wear tracks revealed that the wear mechanism was different for the two test conditions. Wear in the dry test condition resulted from 2-body abrasion, while 3-body abrasion dominated wear in slurry conditions. The latter showed lower wear rates due to a lubricating effect of the oil.

  13. COMPOSITION EFFECT ON DRY SLIDING WEAR BEHAVIORS OF Ti-B-N THIN FILMS

    Institute of Scientific and Technical Information of China (English)

    P. Sit; Y.H. Lu; H. Chen; Z.F. Zhou; Y.G. Shen; K.Y. Li

    2005-01-01

    Friction and sliding wear behaviour of Ti-B-N coatings against AISI440C steel ball and WC-6wt%Co ball were studied by using pin-on-disk tribometer along with microstructure characterization using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the wear resistance of film depended on the wear mechanism. In the case of AISI440C steel, adhesive wear were pre-dominant and the wear rate increased sharply to a maximum when N content reach ~38at. %. This might be related to the change of film microstructure and phase configuration, so the least adhesive transfer of tribo-film was observed. If WC-6wt% Co ball was used, less deformation wear debris was observed, this was responsible for the rise of wear rate. Despite of different wear modes, friction coefficients in both cases were found to depend mainly on the formation and the amount of h-BN phase. Elemental analysis by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) revealed that oxygen participated in the wear behavior by reacting with films to form the debris comprised of various types of Ti oxide including TiO, TiO2 and Ti2O3 ,which increased wear resistance.

  14. Friction and wear behavior of electrodeposited amorphous Fe-Co-W alloy deposits

    Institute of Scientific and Technical Information of China (English)

    何凤姣; 雷惊天; 陆欣; 黄宇宁

    2004-01-01

    The microstructures, friction and wear behavior under dry sliding condition of electrodeposited amorphous Fe-Co-W alloy deposits heat treated at different temperatures were studied. A comparative study of hard chrome deposit under the same testing condition was also made. The experimental results show that the hardness and wear resistance of amorphous Fe-Co-W alloy deposits are improved with the increasing of heat treatment temperature, and reach the maximum value at 800 ℃, then decrease above 800 ℃. Under 40 N load, the wear resistance properties of the alloy deposits heat treated at 800 ℃ are superior to those of hard chrome deposit. The main wear mechanisms of amorphous Fe-Co-W alloy deposits heat treated below 600 ℃ are peeling, plastic and flowing deformation; when the deposits are heat treated above 700 ℃, they are plastic and flowing deformation. While the main wear mechanisms of hard chrome are abrasive wear, fatigue and peeling.

  15. Sliding wear behavior of high velocity arc sprayed Fe-Al coating

    Institute of Scientific and Technical Information of China (English)

    朱子新; 徐滨士; 马世宁; 张伟

    2003-01-01

    The friction and wear behavior of Fe-Al intermetallics based coating produced by high velocity arc spraying technique under dry sliding at room temperature were investigated using a ball-on-disc tribotester. The effect of sliding speed on friction coefficient and wear of the coating was studied. The worn surface of the coating was analyzed by scanning electron microscope (SEM) to explore sliding friction and wear mechanism. The results show that the variations of friction coefficient can be divided into three distinct steps during the trail. Both the friction coefficient and the wear of the coating increase with increased sliding speed due to accelerated crack propagation rate and lamellar structure with poor ductility of the coating. The coating surface is subjected to alternately tensile stress and compression stress during sliding wear process, and the predominant wear mechanism of the coatings appears to be brittle fracture and delamination.

  16. Effect of Deformation Mode on the Wear Behavior of NiTi Shape Memory Alloys

    Science.gov (United States)

    Yan, Lina; Liu, Yong

    2016-06-01

    Owing to good biocompatibility, good fatigue resistance, and excellent superelasticity, various types of bio-medical devices based on NiTi shape memory alloy (SMA) have been developed. Due to the complexity in deformation mode in service, for example NiTi implants, accurate assessment/prediction of the surface wear process is difficult. This study aims at providing a further insight into the effect of deformation mode on the wear behavior of NiTi SMA. In the present study, two types of wear testing modes were used, namely sliding wear mode and reciprocating wear mode, to investigate the effect of deformation mode on the wear behavior of NiTi SMA in both martensitic and austenitic states. It was found that, when in martensitic state and under high applied loads, sliding wear mode resulted in more surface damage as compared to that under reciprocating wear mode. When in austenitic state, although similar trends in the coefficient of friction were observed, the coefficient of friction and surface damage in general is less under reciprocating mode than under sliding mode. These observations were further discussed in terms of different deformation mechanisms involved in the wear tests, in particular, the reversibility of martensite variant reorientation and stress-induced phase transformation, respectively.

  17. Wear behavior of tetragonal zirconia polycrystal versus titanium and titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kanbara, Tsunemichi; Yajima, Yasutomo [Department of Oral Implantology, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502 (Japan); Yoshinari, Masao, E-mail: yosinari@tdc.ac.jp [Division of Oral Implant Research, Oral Health Science Center, Tokyo Dental College, 1-2-2 Masago, Mihama-ku, Chiba 261-8502 (Japan)

    2011-04-15

    The aim of this study was to clarify the influence of tetragonal zirconia polycrystal (TZP) on the two-body wear behavior of titanium (Ti). Two-body wear tests were performed using TZP, two grades of cp-Ti or Ti alloy in distilled water, and the cross-sectional area of worn surfaces was measured to evaluate the wear behavior. In addition, the surface hardness and coefficient of friction were determined and an electron probe microanalysis performed to investigate the underlying mechanism of wear. The hardness of TZP was much greater than that of Ti. The coefficient of friction between Ti and Ti showed a higher value than the Ti/TZP combination. Ti was more susceptible to wear by both TZP and Ti than TZP, indicating that the mechanism of wear between TZP and Ti was abrasive wear, whereas that between Ti and Ti was adhesive wear. No remarkable difference in the amount of wear in Ti was observed between TZP and Ti as the opposite material, despite the hardness value of Ti being much smaller than that of TZP. (communication)

  18. Effects of grain size and humidity on fretting wear in fine-grained alumina, Al{sub 2}O{sub 3}/TiC, and zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Krell, A. [Fraunhofer Inst. for Ceramic Technologies and Sintered Materials, Dresden (Germany); Klaffke, D. [Federal Inst. for Materials Research and Testing, Berlin (Germany)

    1996-05-01

    Friction and wear of sintered alumina with grain sizes between 0.4 and 3 {micro}m were measured in comparison with Al{sub 2}O{sub 3}/TiC composites and with tetragonal ZrO{sub 2} (3 mol% Y{sub 2}O{sub 3}). The dependence on the grain boundary toughness and residual microstresses is investigated, and a hierarchical order of influencing parameters is observed. In air, reduced alumina grain sizes improve the micromechanical stability of the grain boundaries and the hardness, and reduced wear is governed by microplastic deformation, with few pullout events. Humidity and water slightly reduce the friction of all of the investigated ceramics. In water, this effect reduces the wear of coarser alumina microstructures. The wear of aluminas and of the Al{sub 2}O{sub 3}/TiC composite is similar; it is lower than observed in zirconia, where extended surface cracking occurs at grain sizes as small as 0.3 {micro}m.

  19. A comparative study on the wear behaviors of cladding candidates for accident-tolerant fuel

    Science.gov (United States)

    Lee, Young-Ho; Byun, Thak Sang

    2015-10-01

    Accident-tolerant fuels are expected to have considerably longer coping time to respond to the loss of active cooling under severe accidents and, at the same time, have comparable or improved fuel performance during normal operation. The wear resistance of accident tolerant fuels, therefore, needs to be examined to determine the applicability of these cladding candidates to the current operating PWRs because the most common failure of nuclear fuel claddings is still caused by grid-to-rod fretting during normal operations. In this study, reciprocating sliding wear tests on three kinds of cladding candidates for accident-tolerant fuels have been performed to investigate the tribological compatibilities of self-mated cladding candidates and to determine the direct applicability of conventional Zirconium-based alloys as supporting structural materials. The friction coefficients of the cladding candidates are strongly influenced by the test environments and coupled materials. The wear test results under water lubrication conditions indicate that the supporting structural materials for the cladding candidates of accident-tolerant fuels need to be replaced with the same cladding materials instead of using conventional Zirconium-based alloys.

  20. Effects of gap size and excitation frequency on the vibrational behavior and wear rate of fuel rods

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Zupan [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Thouless, M.D., E-mail: thouless@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Materials Science & Engineering, University of Michigan, Ann Arbor, MI 48109 (United States); Lu, Wei, E-mail: weilu@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109 (United States)

    2016-11-15

    Graphical abstract: A wear map shows wear rate as a function of the grid-to-rod gap size and the frequency of the excitation force. The critical gap size, which is associated with the maximum wear rate, lies within the harmonic regime. In the no wear region the amplitude of the rod vibration is smaller than the gap size so that no impact between the rod and plate can happen. The curve of the resonant frequency of the system appears to overlap with the peaks in the contour. - Highlights: • A 3D finite-element based approach to study grid-to-rod fretting. • Two important factors: grid-to-rod gap size and frequency of the excitation force. • Rod vibration shows three regimes: harmonic, period-doubling and chaotic. • A critical gap size is associated with the maximum wear rate. • A wear map shows wear rate as a function of the gap size and excitation frequency. - Abstract: Grid-to-rod fretting (GTRF) wear is a major cause of fuel leaks. Understanding its mechanism is crucial for improving the reliability of nuclear reactors. In this paper we present a three-dimensional, finite-element based approach, which reveals how the wear rate depends on the size of the gap between the grid and the fuel rod, and on the frequency of the excitation force. We show that these two factors affect the dynamic vibration of the rod, which leads to three different regimes: harmonic, period-doubling and chaotic. The wear rate in the harmonic regime is significantly larger than that in the other two regimes, and reaches a maximum when the excitation frequency is close to the resonant frequency of the system, which is dependent on the gap size. We introduce the concept of a critical gap size that gives the maximum wear rate, and we identify the properties and values of this critical gap size. A wear map is developed as a result of a large number of parametric studies. This map shows quantitatively the wear rate as a function of the gap size and excitation frequency, and will be a

  1. CONSIDERATIONS REGARDING THE FRETTING PHENOMENON USING LEAF SPRINGS

    Directory of Open Access Journals (Sweden)

    Stefan GHIMIȘI

    2015-05-01

    Full Text Available The fretting phenomenon represents particulary and complex form of wear who is; generaly, and/or weary of fretting who is produced on the load contact in a relative oscialatory movement lay small amplitude.A simultaneoustly applied tangential force and normal into contact appears a adhesion force

  2. Sliding Wear Behavior of Plasma Sprayed Zirconia Coating on Cast Aluminum against Silicon Carbide Ceramic

    Institute of Scientific and Technical Information of China (English)

    Thuong-Hien LE; Young-Hun CHAE; Seock-Sam KIM

    2005-01-01

    The sliding wear behaviors of ZrO2-22 wt pct MgO (MZ) and ZrO2-8 wt pct Y2O3 (YZ) coatings deposited on a cast aluminum alloy with bond layer (NiCrCoAlY) by plasma spray were investigated under dry test conditions at room temperature. Under all load conditions, the wear mechanisms of the MZ and YZ coatings were almost the same.The material transfer and pullout were involved in the wear process of the studied coatings under the test conditions.The wear rate of the MZ coating was less than that of the YZ coating. While increasing the normal load, the wear rates of the MZ and YZ coatings increased. SEM was used to examine the worn surfaces and to elucidate likely wear mechanisms. Energy dispersive X-ray spectroscopy (EDX) analysis of the worn surfaces indicated that material transfer occurred in the direction from the SiC ball to the disk. Fracture toughness had a significant influence on the wear performance of the coatings. It was suggested that the material transfer played an important role in the wear behavior.

  3. Sliding contacts on printed circuit boards and wear behavior

    Science.gov (United States)

    Le Solleu, J.-P.

    2010-04-01

    Automotive suppliers use since decades printed circuit boards (PCB) gold plating pads, as direct contact interface for low current sliding contacts. Several gold plating processes are available on the market, providing various wear behaviour. Some specific galvanic hard gold (AuCo or AuNi). plating was developed on PCB's. This specific plating generates extra costs due to the material quantity and also the process complexity. In a cost driven industry, the challenge is to use a standard low cost PCB for systems requesting high reliability performances. After a brief overview of standard PCB manufacturing processes and especially gold plating processes, the global experimental results of wear behaviour of three different gold plating technologies will be exposed and an explanation of the correlation between surface key parameters and wear out will be provided.

  4. Wear Behavior of Aluminum Matrix Hybrid Composites Fabricated through Friction Stir Welding Process

    Institute of Scientific and Technical Information of China (English)

    Halil Ibrahim KURT; Murat ODUNCUOGLU; Ramazan ASMATULU

    2016-01-01

    Effects of friction stir processing (FSP)parameters and reinforcements on the wear behavior of 6061-T6 based hybrid composites were investigated.A mathematical formulation was derived to calculate the wear volume loss of the composites.The experimental results were contrasted with the results of the proposed model.The influ-ences of sliding distance,tool traverse and rotational speeds,as well as graphite (Gr)and titanium carbide (TiC) volume fractions on the wear volume loss of the composites were also investigated using the prepared formulation. The results demonstrated that the wear volume loss of the composites significantly increased with increasing sliding distance,tool traverse speed,and rotational speed;while the wear volume loss decreased with increasing volume fraction of the reinforcements.A minimum wear volume loss for the hybrid composites with complex reinforcements was specified at the inclusion ratio of 50% TiC+50% Al2 O3 because of improved lubricant ability,as well as resist-ance to brittleness and wear.New possibilities to develop wear-resistant aluminum-based composites for different in-dustrial applications were proposed.

  5. Casting fabrication of in situ Al3Ti-Al composites and their wear behaviors

    Institute of Scientific and Technical Information of China (English)

    Chen Tijun; Li Jian; Hao Yuan

    2009-01-01

    The Al3li intermetallic reinforced pure Al, Al-13Si and Al-17Cu matrix composites were prepared by casting method. Their microstructures and dry sliding wear behaviors at room temperature and 100℃ were particularly investigated. The results indicated that the Al3Ti phases in these composites were all in flaky form. But the aspect ratio of the Al3Ti platelets decreased with the increase of Ti content in the pure AI, Al-Cu and Al-Si matrix composites, in order of effectiveness. The effect of Si on the Al3Ti morphology seemed to be greater than that of Cu. The distributions of the Al3Ti platelets were different in the different matrix composites, leading to different grain refining effects. Except for the sub-wear regime of adhesive wear, the plastic deformation induced wear was a dominant wear mechanism for all of the composites at room temperature and 100℃. Increasing the testing temperature, decreasing the Al3Ti content or the hardness of materials could enhance these two wear mechanisms, and thus increase the wear rate. The Al-Cu matrix composite had the best wear resistance, while the pure Al matrix composite showed the worst for the same Ti content. These differences or changes were attributed to the differences in materials' hardness or the strengthening effects of the Al3Ti platelets.

  6. Changing life jacket wearing behavior: an evaluation of two approaches.

    Science.gov (United States)

    Mangione, Thomas; Chow, Wendy

    2014-05-01

    In the United States during 1999-2012, about 4 per cent of adults wore life jackets while engaged in recreation on powerboats. Educational campaigns have promoted life jacket use. Mandatory use regulations target primarily children or boaters on personal watercrafts or water skiing. We describe findings from two interventions - 'Wear It California!', a targeted marketing campaign in the California Delta region and mandatory wear regulations at four US Army Corps of Engineers (USACE) lakes in the state of Mississippi. Before the campaign in the Delta, adult wear was 8.5 per cent, increasing to 12.1 per cent during the first year, dipping to 9.4 per cent during the second year, and rising slightly to 10.5 per cent 3 plus years after the campaign. Before mandatory regulations at USACE lakes, adult wear was 13.7 per cent, increasing to 75.6 per cent during the first year, 70.1 per cent during the second year, and remaining high at 68.1 per cent in the third year. Policymakers should consider these findings when choosing how to increase life jacket use.

  7. Wear behavior of an austempered ductile iron containing Mo-Ni-Cu

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, S.; Rahimi, M.A. [Faculty of Materials Engineering, Sahand Univ. of Technology, Tabriz (Iran)

    2005-07-01

    The aim of the this investigation is to study the influence of Ni on tribiological behavior of an austempered ductile iron (ADI) containing Mo, Ni and Cu. Ductile irons with chemical composition Fe-3.56%C-2.67%Si -0.25%Mo-0.5%Cu and Ni contents of 0.8 and 1.5% were cast into standard Y-blocks. Wear test samples were machined off from the bottom section of blocks. Austenitizing heat treatment was carried out at 870 C temperature followed by austempering at 270, 320, and 370 C for 5-1140 minutes. The wear test was carried out by using block-on-ring test machine. Sliding dry wear behavior was studied under applied loads of 50, 100 and 150 N. The results show that wear resistance is independent of austempering temperature with an applied load of 50 N, but there is a strong dependence at higher austempering temperatures with applied loads of 100 and 150 N. Wear mechanism is described as being due to subsurface fatigue, with cracks nucleated at plastically, deformed graphite interfaces. The wear controlling mechanism is the crack growth when wear shows a dependence on applied load and austempering temperature. (orig.)

  8. Effect of periwinkles shell particle size on the wear behavior of asbestos free brake pad

    Science.gov (United States)

    Amaren, S. G.; Yawas, D. S.; Aku, S. Y.

    The effect of periwinkle shell particle size on the wear behavior of asbestos free brake pad has been investigated. The asbestos free brake pad produced by varying the periwinkle shell particles was from +125 to +710 μm with phenolic resin as the binder. The wear test was performed using pin on disk machine by varying the sliding speed, applied load, temperatures and periwinkle shell particle size. Full factorial design of four factor-two levels and analysis of variance were used in the study of the wear test. The results shown that wear rate increases with increasing the sliding speed, load, temperatures and periwinkle particle size. The co-efficient of friction obtained is within the recommended standard for automobile brake pad. The +125 μm particles of periwinkles gave the best wear resistance. Factorial design of the experiment can be successfully employed to describe the wear behavior of the samples and developed linear equation for predicting wear rate within selected experimental conditions. The results of this research indicate that periwinkle shell particles can be effectively used as a replacement for asbestos in brake pad manufacture.

  9. Improvement the wear behavior of low carbon steels by friction stir processing

    Science.gov (United States)

    Sekban, D. M.; Aktarer, S. M.; Yanar, H.; Alsaran, A.; Purcek, G.

    2017-02-01

    A low carbon structural steel was surface-hardened by friction stir processing (FSP) through 4 mm thickness from the surface. The hardness of the alloy increased from 140 Hv0.1 to about 240 Hv0.1 after single-pass FSP. This improvement came from the substantial microstructural refinement due to both severe plastic deformation and dynamic recrystallization. Both yield and tensile strength of the alloy increased without a considerable decrease in ductility after FSP. Friction and wear behavior of the alloy before and after FSP was investigated by a pin-on-disk type tribometer according to ASTM-G133. The substantial increase in both hardness and yield strength resulted in a considerable improvement in wear resistance of the alloy depending on applied pressure. In this study, metallurgical and mechanical reasons for such improvement in wear behavior and any change in wear mechanisms after FSP were investigated.

  10. Process Optimization and Wear Behavior of Red Mud Reinforced Aluminum Composites

    Directory of Open Access Journals (Sweden)

    Rajesh Shanmugavel

    2016-01-01

    Full Text Available This work presents the application of hybrid approach for optimizing the dry sliding wear behavior of red mud based aluminum metal matrix composites (MMCs. The essential input parameters are identified as applied load, sliding velocity, wt.% of reinforcement, and hardness of the counterpart material, whereas the output responses are specific wear rate and Coefficient of Friction (COF. The Grey Relational Analysis (GRA is performed to optimize the multiple performance characteristics simultaneously. The Principle Component Analysis (PCA and entropy methods are applied to evaluate the values of weights corresponding to each output response. The experimental result shows that the wt.% of reinforcements (Q=34.9% followed by the sliding velocity (Q=34.5% contributed more to affecting the dry sliding wear behavior. The optimized conditions are verified through the confirmation test, which exhibited an improvement in the grey relational grade of specific wear rate and COF by 0.3 and 0.034, respectively.

  11. Wear behavior of SiC, Cr{sub 3}C{sub 2} and WC doped alumina

    Energy Technology Data Exchange (ETDEWEB)

    Mindivan, H.; Cimenoglu, H.; Kayali, E.S. [Istanbul Technical Univ., Dept. of Metallurgy and Materials Engineering, Istanbul (Turkey); Bakan, H.I. [Tubitak, MAM, Gebze-Kocaeli (Turkey)

    2004-07-01

    In this study, the wear behavior of the pure and carbide (SiC, Cr{sub 3}C{sub 2}, and WC) doped alumina was investigated. Carbide doping increased the hardness and improved the wear resistance, significantly. WC doped alumina exhibited the highest hardness and wear resistance. (orig.)

  12. Sliding contacts on printed circuit boards and wear behavior

    OpenAIRE

    Le Solleu, J.-P.

    2010-01-01

    Abstract Automotive suppliers use since decades printed circuit boards (PCB) gold plating pads, as direct contact interface for low current sliding contacts. Several gold plating processes are available on the market, providing various wear behaviour. Some specific galvanic hard gold (AuCo or AuNi). plating was developed on PCB's. This specific plating generates extra costs due to the material quantity and also the process complexity. In a cost driven indust...

  13. Friction and wear behavior of carbon fiber reinforced brake materials

    Institute of Scientific and Technical Information of China (English)

    Du-qing CHENG; Xue-tao WANG; Jian ZHU; Dong-bua QIU; Xiu-wei CHENG; Qing-feng GUAN

    2009-01-01

    A new composite brake material was fabri-cated with metallic powders, barium sulphate and modified phenolic resin as the matrix and carbon fiber as the reinforced material. The friction, wear and fade character-istics of this composite were determined using a D-MS friction material testing machine. The surface structure of carbon fiber reinforced friction materials was analyzed by scanning electronic microscopy (SEM). Glass fiber-reinforced and asbestos fiber-reinforced composites with the same matrix were also fabricated for comparison. The carbon fiber-reinforced friction materials (CFRFM) shows lower wear rate than those of glass fiber- and asbestos fiber-reinforced composites in the temperature range of 100℃-300℃. It is interesting that the frictional coefficient of the carbon fiber-reinforced friction materials increases as frictional temperature increases from 100℃ to 300℃, while the frictional coefficients of the other two composites decrease during the increasing temperatures. Based on the SEM observation, the wear mechanism of CFRFM at low temperatures included fiber thinning and pull-out. At high temperature, the phenolic matrix was degraded and more pull-out enhanced fiber was demonstrated. The properties of carbon fiber may be the main reason that the CFRFM possess excellent tribological performances.

  14. Friction and Wear Behaviors of Nano-Silicates in Water

    Institute of Scientific and Technical Information of China (English)

    Chen Boshui; Lou Fang; Fang Jianhua; Wang Jiu; Li Jia

    2009-01-01

    Nano-metric magnesium silicate and zinc silicate with particle size of about 50--70nm were prepared in water by the method of chemical deposition. The antiwear and friction reducing abilities of the nano-silicates, as well as their compos-ites with oleie acid tri-ethanolamine (OATEA), were evaluated on a four-ball friction tester. The topographies and tribochemical features of the worn surfaces were analyzed by scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS). Results show that nano-silicates alone provide poor antiwear and friction reducing abilities in water, but exhibits excellent synergism with OATEA in reducing friction and wear. The synergism in reducing friction and wear between naao-silicates and OATEA does exist almost regardless of particle sizes and species, and may be attributed, on one hand, to the formation of an adsorption film of OATEA, and, on the other hand, to the formation oftdbochemical species of silicon dioxide and iron oxides on the friction surfaces. Tribo-reactions and tribo-adsorptions of nano-silicates and OATEA would produce hereby an effective composite boondary lubrication film, which could efficiently enhance the anti-wear and friction-reducing abilities of water.

  15. The Dry Sliding Wear Behavior of HVOF-Sprayed WC: Metal Composite Coatings

    Science.gov (United States)

    Ward, Liam P.; Pilkington, Antony

    2014-09-01

    WC-based cermet coatings containing various metallic binders such as Ni, Co, and Cr are known for their superior tribological properties, particularly abrasion resistance and enhanced surface hardness. Consequently, these systems are considered as replacements for traditional hard chrome coatings in critical aircraft components such as landing gear. The purpose of this investigation was to conduct a comparative study on the dry sliding wear behavior of three WC-based cermet coatings (WC-12Ni, WC-20Cr2C3-7Ni, and WC-10Co-4Cr), when deposited on carbon steel substrates. Ball on disk wear tests were performed on the coatings using a CSEM Tribometer (pin-on-disk) with a 6-mm ruby ball at 20 N applied load, 0.2 m/s sliding velocity, and sliding distances up to 2000 m. Analysis of both the coating wear track and worn ruby ball was performed using optical microscopy and an Alphastep-250 profilometer. The results of the study revealed both wear of the ruby ball and coated disks allowed for a comparison of both the ball wear and coating wear for the systems considered. Generally, the use of Co and Cr as a binder significantly improved the sliding wear resistance of the coating compared to Ni and/or Cr2C3.

  16. Abrasive wear behaviors of high velocity arc sprayed iron aluminum composite coatings

    Institute of Scientific and Technical Information of China (English)

    Weipu Xu; Binshi Xu; Wei Zhang; Zixin Zhu; Yixiong Wu

    2005-01-01

    The High Velocity Arc Spraying (HVAS) technology was used to prepare Fe-Al composite coatings by the adding of different elements into cored wires to obtain different Fe-Al coatings. The added compounds do great effect on the properties of the composite coatings. The microstructures and abrasive wear performances of the coatings were assessed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and THT07-135 high temperature wear equipment. It was found that the adding of Cr3C2 can greatly increase the room temperature wear behavior, and Fe-Al/WC coatings have adapting periods at the beginning of wear experiment. With the rise of temperature, the wear resistance of Fe-Al/Cr3C2 coatings becomes bad from room temperature to 250℃, and then stable from 250℃ to 550℃; the wear resistance of Fe-Al/WC becomes well with the rise of temperature.The adding of Cr and Ni can also improve wear performances of Fe-Al composite coatings.

  17. Sliding Wear Behavior of TiC-Reinforced Cu-4 wt.% Ni Matrix Composites

    Science.gov (United States)

    Jha, Pushkar; Gautam, R. K.; Tyagi, Rajnesh; Kumar, Devendra

    2016-10-01

    The present investigation explores the effect of TiC content on the sliding wear properties of Cu-4 wt.% Ni matrix composites. Cu-4 wt.% Ni - x wt.% TiC ( x = 0, 2, 4 and 8 wt.%) metal matrix composites were developed by powder metallurgy route. Their friction and wear was studied under dry sliding at different loads of 5, 7.5 and 10 N and constant sliding speed of 2 m/s using a pin-on-disk machine. The metallographic observations showed an almost uniform distribution of TiC particles in the matrix. Hardness of the composites increased with increasing TiC content (up to 4 wt.%). Friction and wear results of TiC-reinforced composites show better wear resistance than unreinforced matrix alloy. However, the optimum wear resistance was observed for 4 wt.% TiC-reinforced composites. Worn surfaces of specimens indicated the abrasion as the primary mechanism of wear in all the materials investigated in the study. The observed behavior has been explained on the basis of (1) the hardness which results in a decrease in real area of contact in composites containing TiC particles and (2) the formation of a transfer layer of wear debris on the surface of the composites which protects underlying substrate by inhibiting metal-metal contact.

  18. Wear behavior of gas tunnel type plasma sprayed Zr-based metallic glass composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Yugeswaran, S., E-mail: yugeswaran@gmail.com [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kobayashi, A., E-mail: kobayasi@jwri.osaka-u.ac.jp [Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Suresh, K., E-mail: ksureshphy@gmail.com [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Rao, K.P., E-mail: mekprao@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (China); Subramanian, B., E-mail: subramanianb3@gmail.com [CSIR - Central Electrochemical Research Institute, Karaikudi 630 006 (India)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Zr-based metallic glass composite coatings are prepared by gas tunnel plasma torch. Black-Right-Pointing-Pointer Increasing plasma current increases crystallinity amount and hardness of coatings. Black-Right-Pointing-Pointer Coating produced at 300 A plasma current gives minimum sliding wear rate. Black-Right-Pointing-Pointer Coating produced at higher plasma current gives lower erosive wear rate. - Abstract: Gas tunnel type plasma spraying is a prospective method to produce metallic glass composite coatings with high quality due to its noteworthy feature of process controllability. In this study, Zr{sub 55}Cu{sub 30}Al{sub 10}Ni{sub 5} metallic glass composite coatings were produced by gas tunnel type plasma spraying torch under optimum spraying conditions with selected plasma currents. The formation mechanism, sliding, and erosive wear behaviors of the coatings with respect to plasma current was examined. The phase and thermal analyses as well as microstructure of the plasma sprayed coatings produced at different plasma currents were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques. The sliding and erosive wear behaviors of the coatings were studied using a pin-on-disc and a specially designed erosive wear tester, respectively. The results showed that an increase in plasma current increased the crystalline content in the metallic glass composite coatings, which enhanced the hardness and wear resistance of the coatings.

  19. Corrosion-wear behavior of nanocrystalline Fe88Si12 alloy in acid and alkaline solutions

    Science.gov (United States)

    Fu, Li-cai; Qin, Wen; Yang, Jun; Liu, Wei-min; Zhou, Ling-ping

    2017-01-01

    The corrosion-wear behavior of a nanocrystalline Fe88Si12 alloy disc coupled with a Si3N4 ball was investigated in acid (pH 3) and alkaline (pH 9) aqueous solutions. The dry wear was also measured for reference. The average friction coefficient of Fe88Si12 alloy in the pH 9 solution was approximately 0.2, which was lower than those observed for Fe88Si12 alloy in the pH 3 solution and in the case of dry wear. The fluctuation of the friction coefficient of samples subjected to the pH 9 solution also showed similar characteristics. The wear rate in the pH 9 solution slightly increased with increasing applied load. The wear rate was approximately one order of magnitude less than that in the pH 3 solution and was far lower than that in the case of dry wear, especially at high applied load. The wear traces of Fe88Si12 alloy under different wear conditions were examined and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the tribo-chemical reactions that involve oxidation of the worn surface and hydrolysis of the Si3N4 ball in the acid solution were restricted in the pH 9 aqueous solution. Thus, water lubrication can effectively improve the wear resistance of nanocrystalline Fe88Si12 alloy in the pH 9 aqueous solution.

  20. Accelerated electrospark deposition and the wear behavior of coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, P.Z.; Pan, G.S.; Zhou, Y.; Qu, J.X.; Shao, H.S. [China Univ. of Mining and Technology, Beijing (China). Beijing Graduate School

    1997-12-01

    Electrospark deposition (ESD) is a coating process that is featured by low heat input to the substrate. Low coating efficiency and other limitations influence its wider application. The present paper introduces newly designed ESD equipment, by which a higher coating rate can be reached. The relationship among coating thickness, surface roughness, and process parameters such as pulse energy, pulse frequency, and deposition time are presented. Electrospark deposition coating by the new equipment on AISI 1045 steel (with WC-8% Co as electrode) increases the wear resistance by 5 to 8 times. The micromechanism is investigated by scanning electron microscopy observation.

  1. Wear Behavior of Laser-Cladded Co-Cr-Mo Coating on γ-TiAl Substrate

    Science.gov (United States)

    Barekat, Masoud; Shoja Razavi, Reza; Ghasemi, Ali

    2017-07-01

    In this study, laser cladding of Co-Cr-Mo alloy on a γ-TiAl substrate was performed to investigate the wear behavior of coated and uncoated TiAl alloy at room temperature. Dry sliding wear tests were conducted for coated and uncoated counterfaces against three pins of alumina, Inconel 718 and Co-Cr-Mo. Overall, laser cladding of Co-Cr-Mo powder resulted in the formation of a thick coating with minimal imperfections, as well as increasing the wear resistance of TiAl alloy. The results of wear tests indicated that the relative wear resistance was about 1.97, 2.17, and 1.92 for sliding against alumina, Inconel 718, and Co-Cr-Mo pins, respectively. The investigation of worn surfaces also showed that the abrasive wear mechanism was dominant for all samples. In addition, severe abrasive wear was changed to mild abrasive wear by local formation of chromium-based oxides.

  2. Investigation of the time-dependent wear behavior of veneering ceramic in porcelain fused to metal crowns during chewing simulations.

    Science.gov (United States)

    Guo, Jiawen; Tian, Beimin; Wei, Ran; Wang, Weiguo; Zhang, Hongyun; Wu, Xiaohong; He, Lin; Zhang, Shaofeng

    2014-12-01

    The excessive abrasion of occlusal surfaces in ceramic crowns limits the service life of restorations and their clinical results. However, little is known about the time-dependent wear behavior of ceramic restorations during the chewing process. The aim of this in vitro study was to investigate the dynamic evolution of the wear behavior of veneering porcelain in PFM crowns as wear progressed, as tested in a chewing simulator. Twenty anatomical metal-ceramic crowns were prepared using Ceramco III as the veneering porcelain. Stainless steel balls served as antagonists. The specimens were dynamically loaded in a chewing simulator with 350N up to 2.4×10(6) loading cycles, with additional thermal cycling between 5 and 55°C. During the testing, several checkpoints were applied to measure the substance loss of the crowns' occlusal surfaces and to evaluate the microstructure of the worn areas. After 2.4×10(6) cycles, the entire wear process of the veneering porcelain in the PFM crowns revealed three wear stages (running-in, steady and severe wear stages). The occlusal surfaces showed traces of intensive wear on the worn areas during the running-in wear stage, and they exhibited the propagation of cracks in the subsurface during steady wear stage. When the severe wear stage was reached, the cracks penetrated the ceramic layer, causing the separation of porcelain pieces. It also exhibited a good correlation among the microstructure, the wear loss and the wear rate of worn ceramic restorations. The results suggest that under the conditions of simulated masticatory movement, the wear performance of the veneering porcelain in PFM crowns indicates the apparent similarity of the tribological characteristics of the traditional mechanical system. Additionally, the evaluation of the wear behavior of ceramic restorations should be based on these three wear stages.

  3. Wear behaviors of HVOF sprayed WC-12Co coatings by laser remelting under lubricated condition

    Science.gov (United States)

    Dejun, Kong; Tianyuan, Sheng

    2017-03-01

    A HVOF (high velocity oxygen fuel) sprayed WC-12Co coating was remelted with a CO2 laser. The surface-interface morphologies and phases were analyzed by means of SEM (scanning electron microscopy), and XRD (X-ray diffraction), respectively. The friction and wear behaviors of WC-12Co coating under the dry and lubricated conditions were investigated with a wear test. The morphologies and distributions of chemical elements on worn scar were analyzed with a SEM, and its configured EDS (energy diffusive spectrometer), respectively, and the effects of lubricated condition on COFs (coefficient of friction) and wear performance were also discussed. The results show that the adhesion between the coating and the substrate is stronger after laser remetling (LR), in which mechanical bonding, accompanying with metallurgical bonding, was found. At the load of 80 N, the average COF under the dry and lubricated friction conditions is 0.069, and 0.052, respectively, the latter lowers by 23.3% than the former, and the wear rate under the lubricated condition decreases by 302.3% than that under the dry condition. The wear mechanism under the dry and lubrication conditions is primarily composed of abrasive wear, cracking, and fatigue failure.

  4. Dry Sliding Wear Behavior of Hafnium-Based Bulk Metallic Glass at Room and Elevated Temperatures

    Science.gov (United States)

    Keshri, Anup Kumar; Behl, Lovish; Lahiri, Debrupa; Dulikravich, George S.; Agarwal, Arvind

    2016-09-01

    Dry sliding wear behavior of hafnium-based bulk metallic glass was studied at two loads (5 and 15 N) and two temperatures (298 and 673 K) using aluminum oxide (Al2O3) ball as a wear counterpart. At 5 N load, wear reduced by ~71% on increasing the temperature from 298 to 673 K. At a higher load of 15 N, the weight loss reduction was much lower (45%) on increasing the temperature from 298 to 673 K. Decreased wear weight loss on increasing the temperature was attributed to the increased hardness of the Hf-based metallic glass at high temperatures. Micro-hardness of the alloy at 293 K was found to be 636 Hv, which gradually increased to 655 Hv on annealing at 673 K. Improvement in the hardness at elevated temperature is attributed to: (1) free volume annihilation, (2) surface oxide formation and (3) nano-crystallites precipitation. Reduced wear at elevated temperature resulted in smaller volume of debris generation that restricted three-body wear to obtain lower coefficient of friction (COF) (0.25-0.35) compared to COF (0.65-0.75) at room temperature.

  5. Corrosion and Wear Behaviors of Cr-Doped Diamond-Like Carbon Coatings

    Science.gov (United States)

    Viswanathan, S.; Mohan, L.; Bera, Parthasarathi; Kumar, V. Praveen; Barshilia, Harish C.; Anandan, C.

    2017-08-01

    A combination of plasma-enhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates. The concentrations of Cr in the coatings are varied by changing the parameters of the bipolar pulsed power supply and the argon/acetylene gas composition. The coatings have been studied for composition, morphology, surface nature, nanohardness, corrosion resistance and wear resistance properties. The changes in I D / I G ratio with Cr concentrations have been obtained from Raman spectroscopy studies. Ratio decreases with an increase in Cr concentration, and it has been found to increase at higher Cr concentration, indicating the disorder in the coating. Carbide is formed in Cr-doped DLC coatings as observed from XPS studies. There is a decrease in sp 3/ sp 2 ratios with an increase in Cr concentration, and it increases again at higher Cr concentration. Nanohardness studies show no clear dependence of hardness on Cr concentration. DLC coatings with lower Cr contents have demonstrated better corrosion resistance with better passive behavior in 3.5% NaCl solution, and corrosion potential is observed to move toward nobler (more positive) values. A low coefficient of friction (0.15) at different loads is observed from reciprocating wear studies. Lower wear volume is found at all loads on the Cr-doped DLC coatings. Wear mechanism changes from abrasive wear on the substrate to adhesive wear on the coating.

  6. Wear Behavior of Woven Roving Aramid / Epoxy Composite under Different Conditions

    Directory of Open Access Journals (Sweden)

    Asad A. Khalid

    2012-09-01

    Full Text Available Wear behavior studies of aramid woven roving /epoxy composite has been conducted. Sliding the material against smooth steel counter face under dry and  lubricated with oil conditions has been investigated. Powder of Silicon carbide has been mixed with the epoxy resin and tested also. The powder was mixed in a volumetric fraction of 10% with the epoxy resin. Four Laminates of six layers were fabricated by hand lay up  method. A pin on disc apparatus has been fabricated to conduct the sliding wear tests on specimens of (4 mm   4 mm   12 mm in size have been cut from the four laminates. The effect of sliding condition including dry, lubricated, dry with additives and lubricated with additives have been studied. Wear rate tests have been conducted at different sliding speeds and loads. Results show that the wear characteristics are influenced by the operating conditions and the construction of the composite material used. It was also found that the wear of aramid /epoxy composite onto the steel counter face were significantly reduced by using lubricant and additives but still took place.Keywords: Wear, Composite materials, Woven roving aramid, Epoxy, Additives, Lubricant.

  7. Reciprocating sliding wear behavior of alendronate sodium-loaded UHMWPE under different tribological conditions.

    Science.gov (United States)

    Huang, Jie; Qu, Shuxin; Wang, Jing; Yang, Dan; Duan, Ke; Weng, Jie

    2013-07-01

    The aim of this study is to investigate the tribological behaviors and wear mechanisms of ultra-high molecular weight polyethylene (UHMWPE) loaded with alendronate sodium (ALN), a potential drug to treat osteolysis, under different normal loads and lubrication conditions. A mixture of UHMWPE powder and ALN (1.0 wt.%) solution was dried and hot pressed. The static and dynamic friction coefficients of UHMWPE-ALN were slightly higher than those of UHMWPE except under normal load as 10 N and in 25 v/v % calf serum. The specific wear rates of UHMWPE-ALN and UHMWPE were the lowest in 25 v/v % calf serum compared to those in deionized water or physiological saline. In particular, the specific wear rate of UHMWPE-ALN was lower than that of UHMWPE at 50 N in 25 v/v % calf serum. The main wear mechanisms of UHMWPE and UHMWPE-ALN in deionized water and UHMWPE in physiological saline were abrasive. The main wear mechanism of UHMWPE-ALN in physiological saline was micro-fatigue. In 25 v/v % calf serum, the main wear mechanism of UHMWPE and UHMWPE-ALN was abrasive wear accompanied with plastic deformation. The results of Micro-XRD indicated that the molecular deformation of UHMWPE-ALN and UHMWPE under the lower stress were in the amorphous region but in the crystalline region at the higher stress. These results showed that the wear of UHMWPE-ALN would be reduced under calf serum lubricated, which would be potentially applied to treat osteolysis.

  8. The influence of social networking technologies on female religious veil-wearing behavior in Iran.

    Science.gov (United States)

    Young, Sean D; Shakiba, Abbas; Kwok, Justin; Montazeri, Mohammad Sadegh

    2014-05-01

    Abstract Social networking technologies can influence attitudes, behaviors, and social norms. Research on this topic has been conducted primarily among early adopters of technology and within the United States. However, it is important to evaluate how social media might affect people's behaviors in international settings, especially among countries with longstanding, government recommended, cultural and religious traditions and behaviors, such as Iran. This study seeks to assess whether Iranian women who have been using social networking technologies for a longer time (compared to those who have recently joined) would be less likely to cover themselves with a veil and be more comfortable publicly displaying pictures of this behavior on Facebook. Iranian females (N=253) were selected through snowball sampling from nongovernmental organizations in November 2011 and asked to complete a survey assessing their use of Facebook, concerns about not wearing a veil in Facebook pictures, and their actual likelihood of wearing a veil. Items were combined to measure lack of interest in wearing a veil. Length of time as a Facebook user was significantly associated with not wearing a veil (b=0.16, pnetworking technologies can affect attitudes and behaviors internationally. We discuss methods of using social media for self-presentation and expression, as well as the difficulties (and importance) of studying use of technologies, such as social media, internationally.

  9. Wear and corrosion behavior of W/WC bilayers deposited by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, N.A. de [Excellence Center for Novel Materials, Universidad del Valle, Cali (Colombia); Jaramillo, H.E. [Science and Engineering of Materials Group, Department of Basic Science of Engineering, Universidad Autonoma de Occidente, Cali (Colombia); Department of Energetic and Mechanic, Universidad Autonoma de Occidente, Cali (Colombia); Bejarano, G. [Excellence Center for Novel Materials, Universidad del Valle, Cali (Colombia); Group for Engineering and Materials Development, CDT ASTIN-SENA, Cali (Colombia); Group of Corrosion and Protection, Antioquia University, Medellin (Colombia); Villamil, B.E.; Teran, G. [Richer Young, COLCIENCIAS, Cali (Colombia)

    2007-07-01

    WC/W coatings were deposited by reactive magnetron sputtering using 40%, 60% and 80% methane CH{sub 4} in the gas mixture. The bilayers were grown on to AISI 420 stainless-steel substrates in order to study the wear and corrosion behavior. Before growing the bilayers, one Ti monolayer was grown to improve the adherence of the coatings to the substrate. The wear resistance and the friction coefficient of the coatings were determined using a pin-on-disk tribometer. All coatings had a friction coefficient of about 0.5. The measured weight lost of the bilayers from each probe allowed the qualitative analysis of wear behavior all coatings. The bilayers grown with 80% methane showed the best abrasive wear resistance and adhesion without failure through the coating in the wear track for dry pin-on-disk sliding. Electrochemical corrosion test showed that the bilayers grown with 80% methane were more resistant to corrosion than the ones uncoated. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Differential negative reinforcement of other behavior to increase wearing of a medical bracelet.

    Science.gov (United States)

    Cook, Jennifer L; Rapp, John T; Schulze, Kimberley A

    2015-12-01

    We used a changing criterion design to evaluate the extent to which differential negative reinforcement of other behavior increased compliance with wearing a medical alert bracelet for a young boy with autism. Results showed the duration for which the participant wore the bracelet systematically increased across trials from 5 s to 7 hr over several weeks.

  11. Wear Behavior of Austempered Ductile Iron with Nanosized Additives

    Directory of Open Access Journals (Sweden)

    J. Kaleicheva

    2014-03-01

    Full Text Available The microstructure and properties of austempered ductile iron (ADI strengthened with nanosized addtives of titanium nitride + titanium carbonitride (TiN + TiCN, titanium nitride TiN and cubic boron nitride cBN are investigated. The TiN, TiCN and cBN, nanosized particles are coated by electroless nickel coating EFTTOM-NICKEL prior to the edition to the melt. The spheroidal graphite iron samples are undergoing an austempering, including heating at 900 оС for an hour, after that isothermal retention at 280 оС, 2 h and 380 оС, 2h. The metallographic analysis by optical metallographic microscope GX41 OLIMPUS and hardness measurements by Vickers Method are performed. The structure of the austempered ductile iron consists of lower bainite and upper bainite.Experimental investigation of the wear by fixed abrasive are also carried out. The influence of the nanosized additives on the microstructure, mechanical and tribological properties of the austempered ductile irons (ADI is studied.

  12. Wear behavior and microstructure of hypereutectic Al-Si alloys prepared by selective laser melting

    Science.gov (United States)

    Kang, Nan; Coddet, Pierre; Liao, Hanlin; Baur, Tiphaine; Coddet, Christian

    2016-08-01

    This work investigates the microstructure and wear behavior of hypereutectic Al-Si alloys, in-situ fabricated using selective laser melting of a mixture of eutectic Al-12Si (wt.%) and pure Si powders. The first observation was that the size and morphology of the Si phase are strongly influenced by the laser power. In addition, it was also observed that a high laser power causes serious evaporation of aluminum during the remelting process. Dry sliding wear test and Vickers microhardness measurements were employed to characterize the mechanical properties of the material. The lowest wear rate of about 7.0 × 10-4 mm3 N-1 m-1 was observed for samples having the highest value of relative density (96%) and microhardness (105 Hv0.3).

  13. Microstructure and Wear Behavior of FeBSiNbCr Metallic Glass Coatings

    Institute of Scientific and Technical Information of China (English)

    Jiangbo Cheng; Xiubing Liang; Binshi Xu; Yixiong Wu

    2009-01-01

    In this paper, FeBSiNbCr metallic glass coatings were prepared onto AISI 1045 steel substrate by using wire arc spraying process. The phase and structure of the coating were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and scanning election microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX). The microstructure of the coating consists of full amorphous phase. The coating has high hardness and low porosity. Full density and little oxides are detected in the coating. The mechanical properties, especially wear resistance, were investigated. The relationship between wear behavior and structure of the coatings were analyzed in detail. The main failure mechanism of the metallic glass coating is brittle breaking and fracture. The results indicate that FeBSiNbCr metallic glass coating has excellent resistance to abrasive wear.

  14. Sliding wear and friction behavior of ZA-27 alloy reinforced by Mn-containing intermetallic compounds

    Institute of Scientific and Technical Information of China (English)

    龙雁; 李元元; 张大童; 邱诚; 陈维平

    2002-01-01

    A ZA-27 alloy reinforced with M n-containing intermeta llic compounds was prepared and its tribological behaviors were investigated. By adding Mn, RE, Ti and B into ZA-27 alloy, the test alloy (ZMJ) was fabricated by sand casting. Microstructural analysis shows that considerable amount of Mn-containing intermetallic compounds such as Al5MnZn, Al9(MnZn)2 and Al65 Mn(RE)6Ti4Zn36 are formed. Compared to ZA-27, ZMJ shows better wear resistance, lower friction coefficient and lower temperature rise of worn surface under lubricated sliding condition. ZMJ also shows the lowest steady friction coefficient under dry friction condition. The wear resistance improvement of ZMJ is mainly attributed to the high hardness and good dispersion of these Mn-containing intermetallic compounds. It is indicated that the intermetallic compounds play a dominant role in reducing the sever adhesive and abrasive wear of the ZA-27 alloy.

  15. Effect of Microstructure on the Wear Behavior of Heat Treated SS-304 Stainless Steel

    Directory of Open Access Journals (Sweden)

    S. Kumar

    2016-12-01

    Full Text Available Sliding wear characteristics of some heat treated SS-304 stainless steel against EN-8 steel in dry condition have been studied in the present experimental work. Samples of SS-304 stainless steel have been heated in a muffle furnace in desired temperature and allowed to dwell for two hours. The heated specimen are then cooled in different media namely inside the furnace, open air, cutting grade oil (grade 44 and water at room temperature to obtain different grades of heat treatment. Microstructures and corresponding micro hardness of the samples have been measured along with Feritscopic studies. Wear characteristics have been studied in a multi tribo-tester (Ducom in dry sliding condition against EN-8 steel roller. Speed, load on job and duration of test run have been considered as the experimental parameters. The wear of the samples have been obtained directly from ‘Winducom 2006’ software. Mass loss of the samples before and after operation has also been considered as the measure of wear in the present study. All the samples have been slid against EN-8 steel roller with fixed experimental parameters. The data have been plotted, compared and analyzed. Effect of microstructures as well as micro hardness on the wear behavior has been studied and concluded accordingly.

  16. Comparison of the Wear Behavior of UHMWPE Lubricated by Human Plasma and Brine

    Institute of Scientific and Technical Information of China (English)

    WANG Shi-bo; GE Shi-rong; NORM Gitis; MICHAEL Vinogradov; XIAO Jun

    2007-01-01

    The effect of plasma and brine lubricants on the friction and wear behavior of UHMWPE were studied by using the geometry of a Si3N4 ball sliding on a UHMWPE disc under patterns of uni-directional reciprocation and bi-directional sliding motions. The worn surface and wear particles produced in these two lubricants were analyzed. Sliding motion pattern affected the friction coefficients lubricated with plasma, while seldom affected that lubricated with brine. UHMWPE lubricated with plasma showed about half of the wear rate of that lubricated with brine. The two rates were 0.75 pg/m and 2.19 pg/m for the two motion patterns, respectively. However, wear particles generated in plasma included a greater amount of small particles, compared to that in brine. In uni-directional reciprocation, the main wear mechanism is ploughing both in plasma and in brine. In bi-directional sliding modes, the significant characteristic is ripples on the worn surface in plasma, while there are oriented fibers on the worn surface in brine.

  17. Wear behavior of Ni/WC surface-infiltrated composite coating on copper substrate

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Gui-rong; Ma, Ying; Hao, Yuan [Lanzhou University of Technology, Gansu (China). State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals; Song, Wen-ming [Lanzhou University of Technology, Gansu (China). State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals; Lanzhou Petroleum Machinery Institute, Gansu (China); Li, Jian [Wuhan Research Institute of Materials Protection (China); Lu, Jin-jun [Chinese Academy of Sciences, Lanzhou, Gansu (China). State Key Laboratory of Solid Lubrication

    2016-01-15

    Ni/WC surface-infiltrated composite coating was fabricated on copper alloy substrate through vacuum infiltration casting using Ni-based alloying powder and with different WC particle contents as raw materials. The wear behavior of Ni/WC surface-infiltrated composite coating was investigated using a block-on-ring tester at different loads and sliding speeds at room temperature. Results show that the wear rate of Ni/WC surface-infiltrated composite coating decreased to approximately one-sixth of the wear rate of the Ni-based alloy infiltrated coating. This phenomenon resulted from the supporting function of WC particles under varying loads applied on the specimen surface and the antifriction effect of the transformation layer. Wear rate was reduced by the Ni/WC-infiltrated composite coating with increasing load, especially when the load exceeded 100 N. The friction coefficient decreased with increasing sliding speed for all infiltrated coatings at any load condition. The reduction in the friction coefficient at high sliding speed was larger than that at low sliding speed with increasing load. The wear mechanism was dominated by oxidation under all experimental conditions and accompanied by adhesion and abrasion mechanisms at high load and high sliding speed.

  18. Effect of gallic acid on the wear behavior of early carious enamel

    Energy Technology Data Exchange (ETDEWEB)

    Gao, S S; Huang, S B; Yu, H Y [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Qian, L M, E-mail: yhyang6812@scu.edu.c [Tribology Research Institute, National Traction Power Laboratory, Southwest Jiaotong University, Chengdu 610031 (China)

    2009-06-15

    The purpose of this research was to investigate the wear behavior of early carious enamel remineralized with gallic acid. Forty natural human premolar specimens with early caries lesions were prepared. A remineralization pH-cycling treatment agent of 4000 ppm gallic acid was used for 12 days to treat the early lesions. The changes in microhardness were monitored. Nanoscratch tests were used to evaluate wear resistance. The experimental data were analyzed by using a t-test. The widths of traces were measured by an AMBIOS XP-2 stylus profilometer. After remineralization, all samples re-hardened significantly. The coefficients of friction became higher, and the widths of scratches were larger than they were before remineralization. Gallic acid significantly improved the early carious enamel's hardness. The wear damage of the samples treated with gallic acid was more severe than that of the control group. There were more obvious cracks and delaminations on the traces of the treated group. Compared with the control group, the enamel remineralized with gallic acid had inferior wear resistance. After remineralization, the dominant damage mechanisms of early carious enamel had changed from plastic deformation and adhesive wear to a combination of brittle cracks and delamination of enamel.

  19. Effect of wearing fingers rings on the behavioral and psychological symptoms of dementia: An exploratory study

    Science.gov (United States)

    Yokoi, Teruo; Okamura, Hitoshi; Yamamoto, Tomoka; Watanabe, Katsuya; Yokoi, Shigeko; Atae, Hitoshi; Ueda, Masayuki; Kuwayama, Takahiro; Sakamoto, Shigekazu; Tomino, Saaya; Fujii, Hideo; Honda, Takefumi; Morita, Takayosi; Yukawa, Takafumi; Harada, Nobuko

    2017-01-01

    Objective: This study was conducted to examine the effects of an approach that wears finger rings on elderly females with behavioral and psychological symptoms of dementia. Method: The subjects were seven Japanese dementia patients living in elderly nursing homes. A single-case experimental design was adopted for the study. Each study subject was asked to put rings on her finger (from 9:00 to 19:00) for 7 days. The Neuropsychiatric Inventory, scenes of behavioral and psychological symptoms of dementia, interest in wearing rings, self-awareness, and overall profile were determined to assess the effect on the patients of wearing rings. Results: The majority of nursing care providers stated, based on their assessment, that the “irritability/lability” that was noted during the baseline period disappeared during the ring-wearing intervention period in the three patients who displayed an interest in rings. In the assessment of the self-awareness ability, these three women were aware themselves of their intellect collapsing and were capable of conjecturing their own and others’ minds. It was commonly seen that the nursing staff, even though they had not been asked to do so by the researchers, told the patients, “Mrs. XX, you look so beautiful” when they found a patient wearing rings. Discussion/conclusion: Individuals with low self-esteem are inclined to get angry and display aggression. In subjects with low self-esteem, anger and aggression readily arise when they are slighted by others. Self-esteem is low in those women who are aware of their own status of collapsing intellect. It is concluded that the words of conjuration, “you look so beautiful,” which the wearing of the ring per se by the patient elicited from the caregivers heightened the self-esteem and alleviated “irritability/lability” in the study subjects. PMID:28856006

  20. Wear behavior of electroless Ni-P-W coating under lubricated condition - a Taguchi based approach

    Science.gov (United States)

    Mukhopadhyay, Arkadeb; Duari, Santanu; Barman, Tapan Kumar; Sahoo, Prasanta

    2016-09-01

    The present study aims to investigate the tribological behavior of electroless Ni-P-W coating under engine oil lubricated condition to ascertain its suitability in automotive applications. Coating is deposited onto mild steel specimens by the electroless method. The experiments are carried out on a pin - on - disc type tribo tester under lubrication. Three tribotesting parameters namely the applied normal load, sliding speed and sliding duration are varied at their three levels and their effects on the wear depth of the deposits are studied. The experiments are carried out based on the combinations available in Taguchi's L27 orthogonal array (OA). Optimization of the tribo-testing parameters is carried out using Taguchi's S/N ratio method to minimize the wear depth. Analysis of variance carried out at a confidence level of 99% indicates that the sliding speed is the most significant parameter in controlling the wear behavior of the deposits. Coating characterization is done using scanning electron microscope, energy dispersive X-ray analysis and X-ray diffraction techniques. It is seen that the wear mechanism under lubricated condition is abrasive in nature.

  1. Microstructure and abrasion wear behavior of Ni-based laser cladding alloy layer at high temperature

    Institute of Scientific and Technical Information of China (English)

    LIU Yong; LIU Su-qin; WANG Shun-xing

    2005-01-01

    Ni-based alloy coating on 21-4-N heat-resistant steel was prepared using CO2 laser, and the high-temperature abrasion wear was tested. The microstructure of this cladding layer and its abrasion wear behavior at high temperature by changing compositions and temperatures were investigated by means of optical microscope and scanning electron microscope. Among the three compositions of cladding layer, i.e. Ni21+20%WC+0.5%CeO2, Ni25+20%WC+0.5%CeO2 and Ni60+20%WC+0.5%CeO2, the experimental results show that Ni21+20%WC+0.5%CeO2 cladding layer is made up of finer grains, and presents the best abrasion wear behavior at high temperature. The wear pattern of laser cladding layer is mainly grain abrasion at lower temperature, and it would be changed to adhesive abrasion and oxide abrasion at higher temperature.

  2. RUNNING CONDITION FRETTING MAPS OF POLYMER MATERIALS

    Directory of Open Access Journals (Sweden)

    Szilárd Tamás Vezér

    2009-04-01

    Full Text Available Due to the industrial demand, the determination of the wear behaviour of polymeric materials is an important research task. Rubbers and elastomers are used widely in contacts, where wear is the dominant failure mechanisms. Furthermore, only the material properties under large displacements were investigated in the majority of existing studies. Depending on the input physical parameters of the tribological systems small oscillations are also observed on the measured signals (due to stick-slip like effect in the contact zone of the elastomers. To describe the failure behaviour under this special condition, a novel fretting fatigue test system was developed and built on a electro-dynamical shaker in this study. The contact area were defined with some additional test, like 2D full field strain analysis, compression and creep tests. Based on the methodology developed and applied for steels and polymer composites, Running Condition Fretting Maps for two elastomer grades (HNBR and TPU were determined.

  3. Microstructure and wear behavior of stellite 6 cladding on 17-4 PH stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Gholipour, A. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shamanian, M., E-mail: shamanian@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ashrafizadeh, F. [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2011-04-07

    Research highlights: > The microstructure of the surface layer consisted of carbides embedded in a Co-rich solid solution with dendritic structure. Primary phases formed during the process were identified as Co(FCC) and lamellar eutectic phases (M{sub 23}C{sub 6}, M{sub 6}C, Cr{sub 7}C{sub 3}). > Microhardness profiles showed that hardness increases from interface to the coating surface. This is due to the finer size of the grains at coating surface in comparison to that at interface and also diffusion of Fe adjacent to the interface. > The delamination was suggested as the dominant mechanism of the wear. In this regard, plate-like wear debris consisted of voids and cracks. In addition, due to increase in surface temperature, Cr{sub 2}O{sub 3} oxide phase was formed during wear tests. - Abstract: This paper deals with the investigation of the microstructure and wear behavior of the stellite 6 cladding on precipitation hardening martensitic stainless steel (17-4PH) using gas tungsten arc welding (GTAW) method. 17-4 PH stainless steel is widely used in oil and gas industries. Optical metallography, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were employed to study the microstructure and wear mechanisms. X-ray diffraction analysis was also used to identify phases formed in the coating. The results showed that the microstructure of the surface layer consisted of carbides embedded in a Co-rich solid solution with a dendritic structure. In addition, the dendritic growth in the coating was epitaxial. Primary phases formed during the process were Co (fcc), Co (hcp), lamellar eutectic phases, M{sub 23}C{sub 6} and Cr{sub 7}C{sub 3} type carbides. The results of the wear tests indicated that the delamination was the dominant mechanism. So, it is necessary to apply an inter-layer between the substrate and top coat.

  4. Effect of Heat Treatment on the Abrasive Wear Behavior of High Chromium Iron under Dry Sliding Condition

    Directory of Open Access Journals (Sweden)

    A.A. Ayeni

    2012-06-01

    Full Text Available The effect of heat treatment on the abrasive wear behavior of high chromium cast iron (NF253AHT under dry sliding condition has been investigated. Rectangular cross sectioned samples of the alloy were produced by sand casting. After casting, the samples were machined to equal dimensions of 50 mm x 15 mm x 10 mm and heat treated by annealing, hardening and tempering. Abrasive wear tests were carried out on the samples using the pin-on-disc wear test. The tests were carried out under restricted values of speed, load and time. Within this limit, the hardened sample displayed a superior wear resistance, while the annealed sample displayed the weakest wear resistance. A graphical model (wear map displaying all the wear regimes of the alloy, which may serve as a wear predictive tool was subsequently developed from the results of the wear tests. With the exception of the as-cast and annealed specimen, all other specimens (hardened and tempered have functioned adequately in wear prone environment, but with different degree of effectiveness. Hence, the hardened and tempered samples can be used in shot blast equipments and in the grinding of minerals.

  5. Corrosion and wear behaviors of Al-bronzes in 5.0% H2SO4 solution

    Institute of Scientific and Technical Information of China (English)

    LI Wen-sheng; WANG Zhi-ping; LU Yang; YUAN Li-hua; XIAO Rong-zhen; ZHAO Xu-dong

    2009-01-01

    Steady-state corrosion and wear behaviors of two Al-bronzes, Cu-14Al-X and QAl9-4, in 5.0% H2SO4 solution were investigated. It is found that wear loss of bronzes in 5.0% H2SO4 solution is lower than that in water or in air, namely, it exhibits negative synergy between corrosion and wear. Further analysis shows that corrosive solution plays an important role in cooling of specimen during the sliding wear to prevent the reduction of the surface hardness of specimen, induced by frictional heat. On the other hand, the bronzes suffer a de-alloying corrosion, and a noble copper subsurface and patina form on the specimen surface in corrosive solution, which has a passive function for further corrosion. The noble copper subsurface experiences strain hardening during the corrosion and wear, resulting in the increase of the surface hardness thus the increase in wear resistance.

  6. Compressional behavior of knitted fabrics exposed to repeated wash and wear cycles

    Directory of Open Access Journals (Sweden)

    Stanković Snežana B.

    2006-01-01

    Full Text Available The quality requirements of knitted fabrics nowadays have become highly demanding in terms of appearance and comfort properties. It is well known that yarns are subjected to tension, bending, torsion and compression during the wear and care of apparels. The appropriate selection of raw materials could be the way to reduce the deformation of knits caused by mechanical forces. Keeping in mind the fact that natural fibers and man-made fibers can significantly differ in respect to elastic properties, natural fiber and synthetic fiber knits were produced for the experiment. The experimental material included three different variants of knitted fabrics: 100% hemp knit, 100% PAC knit and hemp 50%/PAC 50% knit. The behavior of knitted fabrics during the relaxation of compression was investigated. In order to indicate the change of the compressional properties of knitted fabrics, the same investigation after undergoing repeated wash and wear cycles (during eight weeks was repeated. Although the structure of the tested samples was the same, there were differences in the compressional behavior of the knitted fabrics. It is obvious that the differences in the elastic properties of hemp and PAC fibers were projected into the knits. Compression curves were drawn in order to obtain an insight into the change of the compressional behavior of knitted fabrics during wear. These curves also enabled a comparative estimation of the compressional behavior of knits made of different yarn components. The surfaces proportional to the work of the compression for each of the cycles, as well as the work of compression between the first and the fifth cycles, of loading-unloading cycles were calculated. In order to compare the tested knitted fabrics, the hysteresis of compression was analyzed from the aspect of ability of elastic recovery. The change in compressional behavior of knits exposed to wear and care cycles was confirmed. However, analysis of the comparative

  7. Analysis of abrasive wear behavior of PTFE composite using Taguchi’s technique

    Directory of Open Access Journals (Sweden)

    Yusuf Şahin

    2015-12-01

    Full Text Available Polymeric composites are widely used for structural, aerospace, and automobile sectors due to their good combination of high specific strength and specific modulus. These two main characteristics make these materials attractive, compared to conventional materials like metal or alloy ones. Some of their typical benefits include easy processing, corrosion resistance, low friction, and damping of noise and vibrations. Wear behavior of Polytetrafluoroethylenes (PTFE and its composites including glass-filled composites and carbon-filled composites are investigated using a pin-on-disc configuration. A plan of experiments in terms of Taguchi technique is carried out to acquire data in controlled way. An orthogonal array (L9 and the analysis of variance are employed to investigate the influence of process parameters on the wear of these composites. Volume loss increased with abrasive size, load, and distance. Furthermore, specific wear rate decreased with increasing grit size, load, sliding distance, whereas, slightly with compressive strength. Optimal process parameters, which minimize the volume loss, were the factor combinations of L1, G3, D1, and C3. Confirmation experiments were conducted to verify the optimal testing parameters. It was found that in terms of volume loss, there was a good agreement between the estimated and the experimental value of S/N ratio with an error of 1.604%. Moreover, abrasive size, load, and sliding distance exerted a great effect on the specific wear rate, at 51.14, 27.77, and 14.70%, respectively.

  8. Wear Behavior of Mechanically Alloyed Ti-Based Bulk Metallic Glass Composites Containing Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yung-Sheng Lin

    2016-11-01

    Full Text Available The present paper reports the preparation and wear behavior of mechanically alloyed Ti-based bulk metallic glass composites containing carbon nanotube (CNT particles. The differential scanning calorimeter results show that the thermal stability of the amorphous matrix is affected by the presence of CNT particles. Changes in glass transition temperature (Tg and crystallization temperature (Tx suggest that deviations in the chemical composition of the amorphous matrix occurred because of a partial dissolution of the CNT species into the amorphous phase. Although the hardness of CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composites is increased with the addition of CNT particles, the wear resistance of such composites is not directly proportional to their hardness, and does not follow the standard wear law. A worn surface under a high applied load shows that the 12 vol. % CNT/Ti50Cu28Ni15Sn7 bulk metallic glass composite suffers severe wear compared with monolithic Ti50Cu28Ni15Sn7 bulk metallic glass.

  9. Preparation of Ni-CNT composite coatings on aluminum substrate and its friction and wear behavior

    Institute of Scientific and Technical Information of China (English)

    涂江平; 朱丽萍; 陈卫祥; 赵新兵; 刘芙; 张孝彬

    2004-01-01

    Nickel-carbon nanotube(CNT) composite coatings with a Zn-Ni interlayer were prepared by electrodeposition technique on aluminum substrate. The effects of CNT concentration in plating bath on the volume fraction of CNTs in the deposits and the coating growth rate were investigated. The friction and wear behavior of the Ni-CNT composite coatings were examined using a pin-on-disk wear tester under dry sliding conditions at a sliding speed of 0. 062 3 m/s and load range from 12 N to 150 N. Because of the reinforcement of CNTs in the composite coatings, at lower applied loads, the wear resistance was improved with increasing volume fraction of CNTs. Since cracking and peeling occur on the worn surface, the wear rates of composite coatings with high volume fraction of CNTs increase rapidly at higher applied loads. The friction coefficient of the composite coatings decreases with the increasing volume fraction of CNTs due to the reinforcement and self-lubrication of CNTs.

  10. Considerations regarding the volume fraction influence on the wear behavior of the fiber reinforced composite systems

    Science.gov (United States)

    Caliman, R.

    2017-08-01

    This paper contains an analysis of the factors that have an influence on the tribological characteristics of the composite material sintered with metal matrix reinforced with carbon fibers. These composites are used generally if it’s needed the wear resistant materials, whereas these composites have high specific strength in conjunction with a good corrosion resistance at low densities and some self-lubricating properties. Through the knowledge of the better tribological properties of the materials and their behavior to wear, can be generated by dry and the wet friction. Thus, where necessary the use of high temperature resistant material with low friction between the elements, carbon fiber composite materials are very suitable because they have: mechanical strength and good ductility, melting temperature on the higher values, higher electrical and thermal conductivity, lower wear speed and lower friction forces. For this purpose, this paper also contains an experimental program based on the evidence of formaldehyde resin made from fiber reinforced Cu-carbon with the aim to specifically determine the volume of fibers fraction for the consolidation of the composite material. In order to determine the friction coefficient and the wear rates of the various fiber reinforced polymer mixtures of carbon have been used special devices with needle-type with steel disc. These tests were conducted in the atmosphere at the room temperature without external lubrication study taking into consideration the sliding different speeds with constant loading task.

  11. Effect of Load on Friction-Wear Behavior of HVOF-Sprayed WC-12Co Coatings

    Science.gov (United States)

    Yifu, Jin; Weicheng, Kong; Tianyuan, Sheng; Ruihong, Zhang; Dejun, Kong

    2017-07-01

    A WC-12Co coating was sprayed on AISI H13 hot work mold steel using a high-velocity oxygen fuel. The morphologies, phase compositions, and distributions of chemical elements of the obtained coatings were analyzed using a field emission scanning electron microscope, x-ray diffraction, and energy-dispersive spectroscope (EDS), respectively. The friction-wear behaviors under different loads were investigated using a reciprocating wear tester; the morphologies and distributions of the chemical elements of worn tracks were analyzed using a SEM and its configured EDS, respectively. The results show the reunited grains of WC are held together by the Co binder; the primary phases of the coating are WC, Co, and a small amount of W2C and W, owing to the oxidation and decarburization of WC. Inter-diffusion of Fe and W between the coating and the substrate is shown, which indicates a good coating adhesion. The values of the average coefficient of friction under the loads of 40, 80, and 120 N are 0.29, 0.31, and 0.49, respectively. The WC grains are pulled out of the coating during the sliding wear test, but the coating maintains its integrity, suggesting that the coating is intact and continuously protects the substrate from wearing.

  12. Effect of electromagnetic stirring on the microstructure and wear behavior of iron-based composite coatings

    Institute of Scientific and Technical Information of China (English)

    Jiangbo Cheng; Binshi Xu; Xiubing Liang; Yixiong Wu; Zhengun Liu

    2008-01-01

    The effect of electromagnetic stirring on the microstructure and wear behavior of coatings has been investigated. A series of iron-based coatings were fabricated by the plasma-transferred arc cladding process by applying different magnetic field currents. The microstructure and wear resistance of the composite coatings were characterized by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), and wet sand rubber wheel abrasion tester. The experimental results showed that the microstructure of the coatings was mainly theγ-Fe matrix and (Cr, Fe)7C3 carbide reinforced phase. The coatings were metallurgically bonded to the substrate. With increasing magnetic field current, the amount of the block-like (Cr, Fe)7C>3 carbide reinforced phase increased at first, reached a local maximum, and then decreased sharply. When the magnetic field current reached 3 A, the block-like (Cr, Fe)7C3 carbides with high volume fraction were uniformly distributed in the matrix and the coating displayed a high microhardness and an excellent wear resistance under the wear test condition.

  13. Effect of active screen plasma nitriding pretreatment on wear behavior of TiN coating deposited by PACVD technique

    Energy Technology Data Exchange (ETDEWEB)

    Raoufi, M., E-mail: raoufi@iust.ac.ir [School of Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Mirdamadi, Sh. [School of Metallurgical Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of); Mahboubi, F. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Ahangarani, Sh. [Advanced Materials and Renewable Energies Dep., Iranian Research Organization for Science and Technology (Iran, Islamic Republic of); Mahdipoor, M.S. [Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Elmkhah, H. [Department of Metallurgical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2012-08-01

    Titanium based alloys are used extensively for improving wear properties of different parts due to their high hardness contents. Titanium nitride (TiN) is among these coatings which can be deposited on surface using various techniques such as CVD, PVD and PACVD. Their weak interface with substrate is one major drawback which can increase the total wear in spite of favorite wear behavior of TiN. Disc shaped samples from AISI H13 (DIN 1.2344) steel were prepared in this study. Single TiN coating was deposited on some of them while others have experienced a TiN deposition by active screen plasma nitriding (ASPN). Hardness at the surface and depth of samples was measured through Vickers micro hardness test which revealed 1810 Hv hardness as the maximum values for a dual-layered ASPN-TiN. Pin-on-disc wear test was done in order to study the wear mechanism. In this regard, the wear behavior of samples was investigated against pins from 100Cr6 (Din 1.3505) bearing steel and tungsten carbide-cobalt (WC-Co) steel. It was evidenced that the dual-layer ASPN-TiN coating has shown the least weight loss with the best wearing behavior because of its high hardness values, stable interface and acceptable resistance against peeling during wearing period.

  14. Does cyclic stress and accelerated ageing influence the wear behavior of highly crosslinked polyethylene?

    Science.gov (United States)

    Affatato, Saverio; De Mattia, Jonathan Salvatore; Bracco, Pierangiola; Pavoni, Eleonora; Taddei, Paola

    2016-06-01

    First-generation (irradiated and remelted or annealed) and second-generation (irradiated and vitamin E blended or doped) highly crosslinked polyethylenes were introduced in the last decade to solve the problems of wear and osteolysis. In this study, the influence of the Vitamin-E addition on crosslinked polyethylene (XLPE_VE) was evaluated by comparing the in vitro wear behavior of crosslinked polyethylene (XLPE) versus Vitamin-E blended polyethylene XLPE and conventional ultra-high molecular weight polyethylene (STD_PE) acetabular cups, after accelerated ageing according to ASTM F2003-02 (70.0±0.1°C, pure oxygen at 5bar for 14 days). The test was performed using a hip joint simulator run for two millions cycles, under bovine calf serum as lubricant. Mass loss was found to decrease along the series XLPE_VE>STD_PE>XLPE, although no statistically significant differences were found between the mass losses of the three sets of cups. Micro-Raman spectroscopy was used to investigate at a molecular level the morphology changes induced by wear. The spectroscopic analyses showed that the accelerated ageing determined different wear mechanisms and molecular rearrangements during testing with regards to the changes in both the chain orientation and the distribution of the all-trans sequences within the orthorhombic, amorphous and third phases. The results of the present study showed that the addition of vitamin E was not effective to improve the gravimetric wear of PE after accelerated ageing. However, from a molecular point of view, the XLPE_VE acetabular cups tested after accelerated ageing appeared definitely less damaged than the STD_PE ones and comparable to XLPE samples.

  15. A comparative study on the wear behavior of a polymer infiltrated ceramic network (PICN) material and tooth enamel.

    Science.gov (United States)

    Xu, Zhou; Yu, Ping; Arola, Dwayne D; Min, Jie; Gao, Shanshan

    2017-09-20

    To investigate the wear mechanisms of a polymer infiltrated ceramic network (PICN) material, to compare its wear behavior with that of tooth enamel, and to provide evidence relevant to its clinical use. The Vickers hardness (HV) and elastic modulus (E) of a commercial PICN material (ENAMIC) and enamel were measured. Reciprocating wear tests were performed under a ball-on-flat configuration. Three wear pairs were explored including ENAMIC and enamel subjected to Si3N4 ball antagonists and ENAMIC subjected to enamel cusp antagonists. The coefficients of Friction (CoFs) were monitored continuously to 5×10(4) cycles. The wear depth of ENAMIC, enamel specimens and enamel cusps were quantified using white light interferometry, and the wear morphologies were examined using scanning electron microscopy (SEM) to distinguish the wear mechanisms. The HV of ENAMIC is similar to tooth enamel but the E is much lower. For both materials, the CoFs increased sharply in the early stage and then reached plateaus in the later phase. Throughout the cyclic loading history, ENAMIC exhibited larger wear depths than enamel. However, the damage evolution in ENAMIC was similar to that of enamel as the polymer phase was worn preferentially similar to inter-rod enamel, and then the ceramic phase exfoliated from the wear surface akin to enamel rods. The SEM images showed evidence of few cracks within wear tracks of ENAMIC, in comparison to numerous cracks in tooth enamel. ENAMIC has lower wear resistance than tooth enamel, but it exhibits a wear damage mode similar to tooth enamel. Copyright © 2017. Published by Elsevier Ltd.

  16. Wear and Corrosion Behavior of Functionally Graded Nano-SiC/2014Al Composites Produced by Powder Metallurgy

    Science.gov (United States)

    Wang, Zhi-Guo; Li, Chuan-Peng; Wang, Hui-Yuan; Zhu, Jia-Ning; Wang, Cheng; Jiang, Qi-Chuan

    2017-02-01

    Functionally graded 2014Al/SiC composites (FGMs) with varying volume fractions (1-7%) of nano-SiC particulates (n-SiCp) were fabricated by powder metallurgy. The effect of n-SiCp content on corrosion and wear behaviors was studied. The microstructures of composites were characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy. The corrosion behavior of the composites was evaluated by potentiodynamic polarization scans in 3.5 wt.% NaCl solution. Corrosion results show that corrosion current of composite layer with 3 vol.% n-SiC was much lower than that of 2014Al matrix. Mechanical properties of the composites were assessed by microhardness tests and ball-on-disk wear tests. As the applied load changed from 15 to 30 N, wear rates of the composites increased significantly and the wear mechanism transformed from mild to severe wear regime. It also shows that 3 vol.% n-SiCp/2014Al composite layer observed the lowest wear rate where adhesive and abrasive wear mechanisms played a major role. These results suggest that the n-SiCp are effective candidates for fabricating FGMs for the applications demanding a tough core and a hard, wear or corrosion resisting surface.

  17. Effects of Geometrical Clearances, Supports Friction, and Wear Rings on Hydraulic Actuators Bending Behavior

    Directory of Open Access Journals (Sweden)

    Sergio Baragetti

    2016-01-01

    Full Text Available Hydraulic actuators are commonly adopted in machines and structures to provide translating forces with significant magnitudes. Although their application dates back to the industrial revolution, their bending behavior under compression is typically addressed by simple Euler’s instability analysis on the rod, neglecting effects such as the cylinder inertia and stiffness, the presence of contact elements in the cylinder-rod junction and on the piston, geometrical misalignments and imperfections, and friction moments at the support. Such simplifications lead to unjustified reduced critical load calculations on the component. In the present paper, a complete mathematical formulation, which accounts for such effects, is presented and validated against experimental data. A numerical sensitivity analysis is conducted, to assess the contributions of initial rectilinear imperfections, wear rings stiffness and dimension, and supports friction on the actuator’s limit buckling load and bending behavior under compression. Results are presented, including the effect of the cited parameters on the buckling load, providing a reliable tool for the mechanical designer. In particular, an optimum position for the wear ring distance is found. Moreover, increased wear ring stiffness and reduced imperfections increase the buckling load and reduce the bending stresses before the critical load.

  18. Effect of the powder particle size on the wear behavior of boronized AISI 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Guenen, Ali [Mustafa Kemal Univ., Hatay (Turkey). Dept. of Metallurgy and Material Engineering; Kuecuek, Yilmaz; Oege, Mecit; Goek, M. Sabri [Bartin Univ. (Turkey). Dept. of Mechanical Engineering; Er, Yusuf [Firat Univ., Elazig (Turkey); Cay, V. Veli [Dicle Univ., Diyarbakir (Turkey). Civil Aviation Higher School

    2015-06-01

    In this study, the AISI 304 steel specimens were boronized with nanoboron of the size of 10 50 nm and commercial Ekabor 3 powders (<1400 μm) at 950 C to 1000 C for 2 h and 4 h. Boronized steel specimens were characterized via SEM, microhardness and XRD analyses. Abrasive wear behavior of the specimens, boronized at different temperatures and treatment durations, were examined. The fixed ball micro-abrasion tests were carried out using the abrasive slurry, prepared with different SiC powder particle sizes on the boronized specimens at different rotational speeds. The specimens boronized with nanoboron powders exhibited a higher hardness and abrasive wear resistance than the samples boronized with the Ekabor 3 powders.

  19. A Fractional Factorial Design Study of Reciprocating Wear Behavior of Al-Si-SiCp Composites at Lubricated Contacts

    Science.gov (United States)

    Rajeev, V. R.; Dwivedi, D. K.; Jain, S. C.

    2011-04-01

    The lubricated reciprocating wear behavior of two composites A319/15%SiCp and A390/15%SiCp produced by the liquid metallurgy route was investigated by means of an indigenously developed reciprocating friction wear test rig using a fractional factorial-design approach. The main purpose was to study the influence of wear and friction test parameters such as applied load, sliding distance, reciprocating velocity, counter surface temperature and silicon content in composites, as well as their interactions on the wear and friction characteristics of these composites. Two output responses (wear loss and coefficient of friction) were measured. The input parameter levels were fixed through pilot experiment conducted in the newly developed reciprocating friction and wear test rig. The counter surface material used for the wear study was cast iron having Vickers hardness of 244 HVN. It had been demonstrated through established equations that A390/15%SiCp composite is subjected to low wear compared to the A319/15%SiCp composite. The experimental results indicate that the proposed mathematical models suggested could adequately describe the performance indicators within the limits of the factors that are being investigated. The applied load, sliding distance, reciprocating velocity, counter surface temperature, and silicon content in composite are the five important factors controlling the friction and wear characteristics of the composite in lubricated condition. Moreover, the two factor interactions have a strong effect on the wear of composites. The results give a comprehensive insight into the wear of the composites.

  20. Large-eddy simulation, fuel rod vibration and grid-to-rod fretting in pressurized water reactors

    Science.gov (United States)

    Christon, Mark A.; Lu, Roger; Bakosi, Jozsef; Nadiga, Balasubramanya T.; Karoutas, Zeses; Berndt, Markus

    2016-10-01

    Grid-to-rod fretting (GTRF) in pressurized water reactors is a flow-induced vibration phenomenon that results in wear and fretting of the cladding material on fuel rods. GTRF is responsible for over 70% of the fuel failures in pressurized water reactors in the United States. Predicting the GTRF wear and concomitant interval between failures is important because of the large costs associated with reactor shutdown and replacement of fuel rod assemblies. The GTRF-induced wear process involves turbulent flow, mechanical vibration, tribology, and time-varying irradiated material properties in complex fuel assembly geometries. This paper presents a new approach for predicting GTRF induced fuel rod wear that uses high-resolution implicit large-eddy simulation to drive nonlinear transient dynamics computations. The GTRF fluid-structure problem is separated into the simulation of the turbulent flow field in the complex-geometry fuel-rod bundles using implicit large-eddy simulation, the calculation of statistics of the resulting fluctuating structural forces, and the nonlinear transient dynamics analysis of the fuel rod. Ultimately, the methods developed here, can be used, in conjunction with operational management, to improve reactor core designs in which fuel rod failures are minimized or potentially eliminated. Robustness of the behavior of both the structural forces computed from the turbulent flow simulations and the results from the transient dynamics analyses highlight the progress made towards achieving a predictive simulation capability for the GTRF problem.

  1. The Wear behavior of UHMWPE against Surface Modified CP-Titanium by Thermal Oxidation

    Directory of Open Access Journals (Sweden)

    B.T. Prayoga

    2016-12-01

    Full Text Available The effects of thermal oxidation duration on hardness, roughness, and wettability of the CP-titanium surfaces were investigated in this paper. The thermal oxidation treatment was done at 700 oC for 12-36 hours in an air atmosphere. The wear behavior of the UHMWPE sliding against treated thermal oxidation of the CP-titanium was tested by a pin-on-plate tribometer under lubrication of the solution of 75 % distilled water and 25 % bovine serum. The results showed that the layer of the oxide titanium was formed on the surface after being treated by the thermal oxidation for 12-36 hours. The oxide titanium layer was dominated by rutile form of TiO2, that offers an improvement of hardness and wettability of the CP-titanium surfaces. The average wear factor of the UHMWPE reduced significantly when the sliding against of the CP-titanium was modified by the thermal oxidation, and the lowest average wear factor was reached when the sliding against the 12 hour oxidized CP-titanium counterfaces.

  2. An investigation of wear behaviors of different Monel alloys produced by powder metallurgy

    Science.gov (United States)

    Esgin, U.; Özyürek, D.; Kaya, H.

    2016-04-01

    In the present study, wear behaviors of Monel 400, Monel 404, Monel R-405 and Monel K-500 alloys produced by Powder Metallurgy (P/M) method were investigated. These compounds prepared from elemental powders were cold-pressed (600 MPa) and then, sintered at 1150°C for 2 hours and cooled down to the room temperature in furnace environment. Monel alloys produced by the P/M method were characterized through scanning electron microscope (SEM+EDS), X-ray diffraction (XRD), hardness and density measurements. In wear tests, standard pin-on-disk type device was used. Specimens produced within four different Monel Alloys were tested under 1ms-1 sliding speed, under three different loads (20N, 30N and 40N) and five different sliding distances (400-2000 m). The results show that Monel Alloys have γ matrix and that Al0,9Ni4,22 intermetallic phase was formed in the structure. Also, the highest hardness value was measured with the Monel K-500 alloy. In wear tests, the maximum weight loss according to the sliding distance, was observed in Monel 400 and Monel 404 alloys while the minimum weight loss was achieved by the Monel K-500 alloy.

  3. Tribological and wear behavior of HfN/VN nanomultilayer coated cutting tools

    Directory of Open Access Journals (Sweden)

    Willian Aperador Chaparro

    2014-03-01

    Full Text Available Wear and tribological behavior of [HfN/VN]n multinanolayers deposited via magnetron sputtering has been exhaustively studied in this work. Enhancement of both hardness and elastic modulus up to 37 GPa and 351 GPa, respectively, was observed as bilayer periods in the coatings were decreased. The sample with a bilayer period (Λ of 15 nm and bilayer number n = 80, showed the lowest friction coefficient (∼0.15 and the highest critical load (72 N, corresponding to 2.2 and 1.38 times better than those values for the coating deposited with n = 1, respectively. Taking into account the latest results of tungsten carbide (WC inserts were used as substrates to improve the mechanical and tribological properties of [HfN/VN]n coatings as a function of increased interface number and to manage higher efficiency of these coatings in different industrial applications, like machining and extrusion. Their physical, mechanical, and tribological characteristics were investigated, including cutting tests with AISI 1020 steel (workpiece to assess wear as a function of the bilayer number and bilayer period. A comparison of the tribological properties revealed a decrease of flank wear (approximately 24% for WC inserts coated with [HfN/VN]80 (Λ =15 nm, when compared to uncoated tungsten carbide inserts. These results demonstrate the possibility of using [HfN/VN] multilayers as new coatings for tool machining with excellent industrial performance.

  4. Investigation on Dry Sliding Wear Behavior of Nylon66/GnP Nano-composite

    Science.gov (United States)

    Sankara Narayana, Kota; Suman, Koka Naga Sai; Arun Vikram, Kothapalli

    2017-04-01

    The tribological behavior of graphene nano platelets (GnP) reinforced Nylon66 polymer Nano composites were studied using a pin-on-disc apparatus under dry sliding conditions. The influence of wear control factors like applied load, velocity, sliding distance and weight percentage of GnP reinforcement on the responses like specific wear rate and frictional coefficient were investigated. Nano composites were developed by melt mixing of various weight fractions of GnP (0/0.5/1/2) with nylon 66 using twin screw extruder. A design of experiments based on the Taguchi technique was performed to acquire data in a controlled way and was successfully used to identify the optimal combinations of control factors influencing the outputs. Analysis of variance was employed to investigate the influence and contribution of control factors on the responses. The results showed that the inclusion of GnP as reinforcing material in Nylon66 Nano composites, decreases the friction coefficient and increases the wear resistance of the Nano composites significantly.

  5. Investigation on Dry Sliding Wear Behavior of Nylon66/GnP Nano-composite

    Science.gov (United States)

    Sankara Narayana, Kota; Suman, Koka Naga Sai; Arun Vikram, Kothapalli

    2016-06-01

    The tribological behavior of graphene nano platelets (GnP) reinforced Nylon66 polymer Nano composites were studied using a pin-on-disc apparatus under dry sliding conditions. The influence of wear control factors like applied load, velocity, sliding distance and weight percentage of GnP reinforcement on the responses like specific wear rate and frictional coefficient were investigated. Nano composites were developed by melt mixing of various weight fractions of GnP (0/0.5/1/2) with nylon 66 using twin screw extruder. A design of experiments based on the Taguchi technique was performed to acquire data in a controlled way and was successfully used to identify the optimal combinations of control factors influencing the outputs. Analysis of variance was employed to investigate the influence and contribution of control factors on the responses. The results showed that the inclusion of GnP as reinforcing material in Nylon66 Nano composites, decreases the friction coefficient and increases the wear resistance of the Nano composites significantly.

  6. Dry sliding wear behavior of an extruded Mg–Dy–Zn alloy with long period stacking ordered phase

    Directory of Open Access Journals (Sweden)

    Guangli Bi

    2015-03-01

    Full Text Available The dry sliding wear behavior of extruded Mg-2Dy-0.5Zn alloy (at.% was investigated using a pin-on-disk configuration. The friction coefficient and wear rate were measured within a load range 20–760 N at a sliding velocity of 0.785 m/s. Microstructure and wear surface of alloy were examined using scanning electron microscopy. The mechanical properties of alloy were tested at room and elevated temperatures. Five wear mechanisms, namely abrasion, oxidation, delamination, thermal softening and melting dominated the whole wear behavior with increasing applied load. The extruded Mg-2Dy-0.5Zn alloy exhibited the better wear resistance as compared with as-cast Mg97Zn1Y2 alloy under the given conditions through contact surface temperature analysis. The improved wear resistance was mainly related to fine grain size, good thermal stability of long period stacking order (LPSO phase and excellent higher-temperature mechanical properties.

  7. Effects of the ratio of hardness to Young's modulus on the friction and wear behavior of bilayer coatings

    Science.gov (United States)

    Ni, Wangyang; Cheng, Yang-Tse; Lukitsch, Michael J.; Weiner, Anita M.; Lev, Lenoid C.; Grummon, David S.

    2004-11-01

    We present a study of the effects of the ratio of hardness to Young's modulus on the friction and wear behavior of layered composite coatings. Layered coating structures with the same surface coating but different interlayers were prepared by physical vapor deposition. We found that the ratio of hardness to Young's modulus plays an important role in determining the friction coefficient and wear resistance of layered composite coatings. A low friction coefficient and high wear resistance can be achieved in structures with high ratio of hardness to Young's modulus and moderately high hardness.

  8. EFFECT OF La2O3 ADDITION ON MICROSTRUCTURE AND WEAR BEHAVIOR OF ELECTROSPARK DEPOSITED Ni-BASED COATINGS

    OpenAIRE

    GAO YUXIN; YI JIAN

    2013-01-01

    La2O3 doped Ni-based coatings have been prepared by electrospark deposition technique. The effect of La2O3 on the microstructure, hardness and wear behavior of the as-prepared Ni-based coatings is investigated by using X-ray diffractometer, scanning electron microscope, wear tribometer and Vickers hardness tester. Results indicates that the microstructure, hardness and wear resistance of La2O3 doped Ni-based coatings are effectively improved as compared to the undoped one, and the coating wit...

  9. Mechanical Properties and Friction/Wear Behavior of Copper Alloyed Powder Composites

    Institute of Scientific and Technical Information of China (English)

    DENG Chen-hong; CHEN Guang-zhi; GE Qi-lu

    2005-01-01

    Copper alloyed powder composites containing nanoparticles were developed by hot pressing. Effects of nanoscale activated sintering aid and fine ceramic particles Al2O3 on hardness, working quality, and behaviors of friction and wear of the composites have been studied, compared with the composites including microscale activated sintering aid and microscale ceramic particles. The microstructures of the samples were analyzed by SEM. The results show that the materials with nanoscale sintering aid and fine ceramic particles have better mechanical properties and abrasive resistance than the materials with microscale activated sintering aid and microceramic particles. Moreover, element mutual transfer occurs between samples (strip) and abrasive wheel (ring).

  10. The Delamination Theory of Wear

    Science.gov (United States)

    1974-09-01

    junctions, it is still based on the assumption that the deformation occurs at the asperities. Rabinowicz [14] advanced an adhesion theory of friction...shown that bronze particles were indeed bigger than steel particles. The compilation of wear particle sizes given by Rabinowicz [14] also indicates...Waterhouse [32] has shown that, in fact, fretting occurs by delamination. 6) Minimum Load for Loose Particle Formation Rabinowicz [14] found that no wear

  11. Study on the Thermal Fatigue Behavior of Hot Deformed Wear Resistance Cast Iron and Effect of Carbide

    Institute of Scientific and Technical Information of China (English)

    Dong Litao; Liu Rongchang; Li Xingyuan; Chen Xiuhong

    2007-01-01

    The thermal fatigue behavior of wear resistance cast iron with different quantity of deformation has been investigated. The results show that eutectic carbide is the main location and passage for initiation and extension of thermal fatigue cracks, approving that the more serious, the carbide breaks. The higher thermal fatigue resistance of wear resistance cast iron will be and thermal fatigue fracture belongs mainly to brittleness.

  12. Friction and wear behavior of nanosilica-filled epoxy resin composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Kang Yingke [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Chen Xinhua, E-mail: xuc0374@163.com [College of Chemistry and Chemical Engineering, Xuchang University, Xuchang 461000 (China); Song Shiyong; Yu Laigui [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China); Zhang Pingyu, E-mail: pingyu@henu.edu.cn [Key Laboratory of Ministry of Education for Special Functional Materials, Henan University, Kaifeng 475004 (China)

    2012-06-15

    Hydrophilic silica nanoparticles (abridged as nano-SiO{sub 2}) surface-capped with epoxide were dispersed in the solution of epoxy resin (abridged as EP) in tetrahydrofuran under magnetic stirring. Resultant suspension of nano-SiO{sub 2} in EP was then coated onto the surface of glass slides and dried at 80 Degree-Sign C in a vacuum oven for 2 h, generating epoxy resin-nanosilica composite coatings (coded as EP/nano-SiO{sub 2}). EP coating without nano-SiO{sub 2} was also prepared as a reference in the same manner. A water contact angle meter and a surface profiler were separately performed to measure the water contact angles and surface roughness of as-prepared EP/nano-SiO{sub 2} composite coatings. The friction and wear behavior of as-prepared EP/nano-SiO{sub 2} composite coatings sliding against steel in a ball-on-plate contact configuration under unlubricated condition was evaluated. Particularly, the effect of coating composition on the friction and wear behavior of the composite coatings was highlighted in relation to their microstructure and worn surface morphology examined by means of scanning electron microscopy. Results indicate that EP/nano-SiO{sub 2} composite coatings have a higher surface roughness and water contact angle than EP coating. The EP-SiO{sub 2} coatings doped with a proper amount of hydrophilic SiO{sub 2} nanoparticles show lower friction coefficient than EP coating. However, the introduction of surface-capped nanosilica as the filler results in inconsistent change in the friction coefficient and wear rate of the filled EP-matrix composites; and it needs further study to achieve well balanced friction-reducing and antiwear abilities of the composite coatings for tribological applications.

  13. Structure and wear behavior of AlCrSiN-based coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yun [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Du, Hao [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Ming, E-mail: mchen@sjtu.edu.cn [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Yang, Jun [Chengdu Tool Research Institute Co., Ltd., Chengdu 610500 (China); Xiong, Ji [School of Manufacturing Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhao, Haibo [The Analysis and Testing Centre, Sichuan University, Chengdu 610065 (China)

    2016-05-01

    Graphical abstract: - Highlights: • AlCrSiN based coating showed amorphous structure. • AlCrSiN/Me{sub x}N coatings obtained better wear resistance. • Molybdenum and niobium increased the coating hardness and wear resistance. - Abstract: AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC–Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N{sub 2} mixtures. Al{sub 0.6}Cr{sub 0.4}, Al{sub 0.6}Cr{sub 0.3}Si{sub 0.1}, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiN{sub x} peak were formed in the AlCrSiN/Me{sub x}N coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H{sup 3}/E{sup 2} ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.

  14. Effect of austempering process on microstructure and wear behavior of ductile iron containing Mn-Ni-Cu-Mo

    Science.gov (United States)

    PourAsiabi, HaMiD; Saghafian, Hasan; Pourasiabi, Hamed

    2013-01-01

    In this work, the effects of austempering time and temperature on the microstructure and sliding wear behavior of a Mn-Ni-Cu-Mo alloyed ductile iron were investigated. Ductile iron samples with the desired chemical composition were cast according to ASTM A897M-1990 Y-block. Wear test samples austenitized at 900 °C for 90 min, were austempered at 260, 290 and 320 °C for 30, 60, 90 and 120 min. The wear tests on samples were conducted by Block-on-Ring testing machine according to ASTM G77-98 standard, at the applied load of 75N and the displacement speed of 3.27 m/s. The results showed that the sample austempered at 260 °C for 90 min exhibited the maximum relative wear resistance in comparison with the as-cast sample. The X-ray diffraction patterns of wear debris and the SEM observations of worn surfaces and crosssection of worn surfaces together with wear debris showed that delamination associated with oxidation is the dominant wear mechanism in the samples.

  15. High-speed friction and wear behaviors of bulk Ti3SiC2

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhen-ying; ZHAI Hong-xiang; ZHOU Wei; ZHOU Yang; AI Ming-xin; ZHANG Zhi-li; LI Shi-bo

    2005-01-01

    High-speed friction and wear behaviors of bulk Ti3 SiC2 sliding drily against low carbon steel were investigated. Tests were carried out using a block-on-disk type tester with normal pressures ranging from 0.1 to 0.8 MPa and several sliding speeds from 20 to 60 m/s. The results show that, in the case of sliding speeds of 20 - 40 m/s, the friction coefficient exhibits a decreasing tendency with increasing the normal pressure after an increment in the smaller pressure range, and the worn quantity of Ti3SiC2 exhibits a nearly linear increase with increasing the normal pressure. However, when the sliding speed is up to 60 m/s, the friction coefficient exhibits a monotonous increase and the worn quantity exhibits a quadric increase with increasing the normal pressure. These speed-dependent and pressure-dependent behaviors are attributed to the antifriction effects of a frictionally generated oxide film covering the friction surface of Ti3SiC2, and a balance between the generating rate and the removing (wearing) rate of the film.

  16. IIem-spFRET: improved Iem-spFRET method for robust FRET measurement

    Science.gov (United States)

    Zhang, Jiang; Lin, Fangrui; Chai, Liuying; Wei, Lichun; Chen, Tongsheng

    2016-10-01

    We recently developed a quantitative Förster resonance energy transfer (FRET) measurement method based on emission-spectral unmixing (Iem-spFRET). We here developed an improved Iem-spFRET method (termed as IIem-spFRET) for more robust FRET measurement in living cells. First, two background (BG) spectral fingerprints measured from blank living cells are introduced to remove BG and autofluorescence. Second, we introduce a ρ factor denoting the ratio of two molar extinction coefficient ratios (γ) of acceptor to donor at two excitations into IIem-spFRET for direct measurement of the γ values using a tandem construct with unknown FRET efficiency (E). We performed IIem-spFRET on our microscope-spectrometer platform to measure the γ values of Venus (V) to Cerulean (C) and the E values of C32V, CVC, VCV, and VCVV constructs, respectively, in living Huh7 cells. For the C32V or CVC cells, the Iem-spFRET and IIem-spFRET methods measured consistent E values. However, for the cells especially with low expressing levels of VCV or VCVV, the E values measured by Iem-spFRET showed large deviations and fluctuations, whereas the IIem-spFRET method greatly improved the measured E values. Collectively, IIem-spFRET is a powerful and robust tool for quantitatively measuring FRET signal in living cells.

  17. Sliding Wear Behavior of Plasma Sprayed Alumina-Based Composite Coatings against Al2O3 Ball

    Institute of Scientific and Technical Information of China (English)

    Minh-quy Le; Young-hun Chae; Seock-sam Kim

    2004-01-01

    The sliding wear behaviors of a single layer Al2O3-30 wt pct ZrO2, a double layer Al2O3-30 wt pct ZrO2/Ni-Cr and a single layer Al2O3-13 wt pct TiO2 coating deposited on low carbon steel by plasma spraying were investigated under lubricated conditions with various normal loads. The plastic deformation, detachment and pull out of splats were involved in the wear process of the studied coatings under test conditions. Crack propagation was found in Al2O3-13 wt pct TiO2 under loads of 70 and 100 N and in Al2O3-30 wt pct ZrO2/Ni-Cr under a load of 130 N.While increasing the normal load, the wear rates of Al2O3-30 wt pct ZrO2 and Al2O3-30 wt pct ZrO2/Ni-Cr slightly increased, the wear rate of Al2O3-13 wt pct TiO2 increased rapidly. The results showed that the Ni-Cr bonding layer improved the wear resistance of the coating system even it is relatively thin compared with the outer coating layer.The influence of this bonding layer on wear behavior of the coating increased as increasing the normal load.

  18. Effect of Micro-addition Rare Earth and Chrome on Friction and Wear Behavior of Boronized layer

    Institute of Scientific and Technical Information of China (English)

    XUBin; WANGShu-hua; LUYu-peng; CUIJian-jun; LIMu-sen

    2004-01-01

    Application of powder boronizing to mechanical industry has been restricted because of the brittleness of boronized layer, which inevitably leeds to decrease of service life of boronized paris. Therefore, attention should be paid to reducing the brittleness of boronized layer without decreasing its high hardness. In the present paper, a study on the effect of micro-additionr are earth and chrome on friction and wear behavior of boronized layer was carded out using an MM-200 wear test machine. Compared with that of pure single Fe2B phase, the brittleness of the boronized layer containing minim rare earth and chrome elements, obtained by powder RE-chrome-boronizing, is reduced, which results in increasing the bearing capacity and wear resistance of the boronized layer, The friction and wear mechanism is also briefly analyzed.

  19. Effect of Micro-addition Rare Earth and Chrome on Friction and Wear Behavior of Boronized layer

    Institute of Scientific and Technical Information of China (English)

    XU Bin; WANG Shu-hua; LU Yu-peng; CUI Jian-jun; LI Mu-sen

    2004-01-01

    Application of powder boronizing to mechanical industry has been restricted because of the brittleness of boronized layer, which inevitably leads to decrease of service life of boronized parts. Therefore, attention should be paid to reducing the brittleness of boronized layer without decreasing its high hardness. In the present paper, a study on the effect of micro-addition rare earth and chrome on friction and wear behavior of boronized layer was carried out using an MM-200 wear test machine.Compared with that of pure single Fe2B phase, the brittleness of the boronized layer containing minim rare earth and chrome elements, obtained by powder RE-chrome-boronizing, is reduced, which results in increasing the bearing capacity and wear resistance of the boronized layer. The friction and wear mechanism is also briefly analyzed.

  20. Microstructural and Wear Behavior Characterization of Porous Layers Produced by Pulsed Laser Irradiation in Glass-Ceramics Substrates

    Directory of Open Access Journals (Sweden)

    Jose I. Peña

    2013-09-01

    Full Text Available In this work, wear behavior and microstructural characterization of porous layers produced in glass-ceramic substrates by pulsed laser irradiation in the nanosecond range are studied under unidirectional sliding conditions against AISI316 and corundum counterbodies. Depending on the optical configuration of the laser beam and on the working parameters, the local temperature and pressure applied over the interaction zone can generate a porous glass-ceramic layer. Material transference from the ball to the porous glass-ceramic layer was observed in the wear tests carried out against the AISI316 ball counterface whereas, in the case of the corundum ball, the wear volume loss was concentrated in the porous layer. Wear rate and friction coefficient presented higher values than expected for dense glass-ceramics.

  1. Corrosion and wear behavior of functionally graded Al2024/SiC composites produced by hot pressing and consolidation

    Energy Technology Data Exchange (ETDEWEB)

    Erdemir, Fatih; Canakci, Aykut, E-mail: aykut@ktu.edu.tr; Varol, Temel; Ozkaya, Serdar

    2015-09-25

    Highlights: • Functionally graded Al2024/SiC composites were produced by hot pressing. • Effect of the number of graded layers was investigated on the corrosion behavior. • Functionally graded composites has the most corrosion resistant than composites. • Wear mechanisms of Al2024/SiC composites were explained. - Abstract: Functionally graded Al2024/SiC composites (FGMs) with varying percentage of SiC (30–60%) were produced by hot pressing and consolidation method. The effects of SiC content and number of layers of Al2024/SiC FGMs on the corrosion and wear behaviors were investigated. The microstructures of these composites were characterized by a scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). The corrosion performances of composites were evaluated by potentiodynamic polarization scans in 3.5% NaCl solution. Corrosion experiments shows that corrosion rate (1109 mpy) of two layered FGMs which containing 50 wt.% SiC were much higher than Al2024 matrix (2569 mpy) and Al2024/50 wt.% SiC composite (2201 mpy). Mechanical properties of these composites were evaluated by microhardness measurements and ball-on-disk wear tests. As the applied load change from 15 to 20 N, the wear rates of the Al2024 increased significantly and wear mechanism transformed from mild to severe wear regime. It has been shown that Al2024/40 wt.% SiC composite has lower wear rate where adhesive and abrasive wear mechanisms play a major role.

  2. Structure and wear behavior of AlCrSiN-based coatings

    Science.gov (United States)

    Chen, Yun; Du, Hao; Chen, Ming; Yang, Jun; Xiong, Ji; Zhao, Haibo

    2016-05-01

    AlCrN, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings have been deposited on high-polished WC-Co cemented carbide substrate and tools by mid-frequency magnetron sputtering in Ar/N2 mixtures. Al0.6Cr0.4, Al0.6Cr0.3Si0.1, and C/Mo/Nb targets were used during the deposition. The microstructure and mechanical properties of as-deposited coatings were investigated. Investigations of the wear behaviors of coated tools were also performed. The results showed that cubic structure was formed in the coatings. Broader CrAlN (1 1 1) and (2 0 0) peaks without SiNx peak were formed in the AlCrSiN/MexN coatings, which showed a nanocomposited structure. Meanwhile, according to SEM micrographs, AlCrN exhibited a columnar structure, while, AlCrSiCN, AlCrSiN/MoN, and AlCrSiN/NbN coatings showed nanocrystalline morphology. The nano-multilayered coatings performed higher hardness, H/E, and H3/E2 ratios compared with AlCrN coating. Through the Rockwell adhesion test, all the coatings exhibited adhesion strength quality HF1. After turning Inconel 718 under dry condition, the nano-multilyered coatings showed better wear resistance than AlCrN coating. Due to the molybdenum and niobium in the coating, AlCrSiN/MoN and AlCrSiN/NbN coatings showed the best wear resistance.

  3. Adhesion, friction, and wear behavior of clean metal-ceramic couples

    Science.gov (United States)

    Miyoshi, Kazuhisa

    1995-01-01

    When a clean metal is brought into contact with a clean, harder ceramic in ultrahigh vacuum, strong bonds form between the two materials. The interfacial bond strength between the metal and ceramic surfaces in sliding contact is generally greater than the cohesive bond strength in the metal. Thus, fracture of the cohesive bonds in the metal results when shearing occurs. These strong interfacial bonds and the shearing fracture in the metal are the main causes of the observed wear behavior and the transfer of the metal to the ceramic. In the literature, the surface energy (bond energy) per unit area of the metal is shown to be related to the degree of interfacial bond strength per unit area. Because the two materials of a metal-ceramic couple have markedly different ductilities, contact can cause considerable plastic deformation of the softer metal. It is the ductility of the metal, then, that determines the real area of contact. In general, the less ductile the metal, the smaller the real area of contact. The coefficient of friction for clean surfaces of metal-ceramic couples correlates with the metals total surface energy in the real area of contact gamma A (which is the product of the surface energy per unit area of the metal gamma and the real area of contact (A)). The coefficient of friction increases as gamma A increases. Furthermore, gamma A is associated with the wear and transfer of the metal at the metal-ceramic interface: the higher the value of gamma A, the greater the wear and transfer of the metal.

  4. Seat-belt wearing and driving behavior: an instrumented-vehicle study.

    Science.gov (United States)

    Janssen, W

    1994-04-01

    Less-than-expected fatality reductions after seat-belt legislation has been introduced in a jurisdiction may be explained in terms of selective recruitment of parts of the driving population and/or behavioral adaptation by beginning belt users. The present investigation has compared the relative merits of these two hypotheses at the level of individual driver behavior. In the initial study the driving behavior of groups of habitual wearers and nonwearers of the belt was compared. Nonwearers made two trips, one with the belt on and one without the belt. Habitual wearers drove belted only. The main part of the experiment was a 105 km freeway route. Two additional tasks of a somewhat more critical nature, a double lane-change manoeuvre and the performance of a braking manoeuvre in front of a fixed obstacle, were performed after the freeway trips. Factor analysis on 39 variables describing driving behavior on the road and during the additional tasks resulted in five factors. One of these, the factor describing the distribution of driving speed on the freeway, differentiated between nonwearers and wearers (thus yielding support for the selective recruitment hypothesis) as well as between wearing and not wearing the belt by the same drivers (thus yielding support for the behavioral adaptation hypothesis). In the follow-up study the original wearers and nonwearers were assigned to one of four experimental treatments: (i) the promise by the experimenter of a considerable incentive for not having a culpable motor vehicle accident over a period of a year. Half the habitual wearer subjects were assigned to this condition. The expectation was that this group would become more careful in their driving; (ii) a control group, consisting of the remaining habitual wearers; (iii) the agreement between the experimenter and the subject that the latter would buckle up in everyday driving for the year to come--half the habitual nonwearer subjects were assigned to this condition; (iv) a

  5. Effect of Different Parameters on Mechanical and Erosion Wear Behavior of Bamboo Fiber Reinforced Epoxy Composites

    Directory of Open Access Journals (Sweden)

    Anu Gupta

    2011-01-01

    Full Text Available The application of natural fibers as reinforcement in polymer composites has been continuously growing during the last few decades. These composites find diverse applications in hostile environment where they are exposed to external attacks such as solid particle erosion. Also, in many respects, the mechanical properties of different polymer composites are their most important characteristics. Therefore, improvement of the erosion resistance and mechanical behavior of polymer composites are the prime requirements in their applications. Bamboo fiber which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for reinforcement in polymers. To this end, an attempt has been made in this paper not only to study the utilization potential of bamboo fiber in polymer composites but also to study the effect of various parameters on mechanical and erosion wear performance of bamboo fiber reinforced epoxy composites.

  6. Comparative Investigation on Brazing Behavior, Compressive Strength, and Wear Properties of Multicrystalline CBN Abrasive Grains

    Directory of Open Access Journals (Sweden)

    Wen-Feng Ding

    2014-05-01

    Full Text Available In order to fabricate the abrasive wheels with good grain self-sharpening capacity, two types of multicrystalline CBN grains, that is, polycrystalline CBN (PCBN and binderless CBN (BCBN, were brazed using Cu-Sn-Ti alloy, respectively. Comparative investigation on the brazing interface, compressive strength, and wear properties of the different grains was carried out. Results obtained show that the PCBN grains have more intricate reaction, more complicated resultants, and thicker reaction layer than the BCBN counterparts under the identical brazing conditions. Though the average compressive strength of the PCBN grains is similar to that of BCBN ones, stronger self-sharpening action by virtue of the microfracture behavior takes place with BCBN grains during grinding. As a consequence, compared to the brazed PCBN wheels and the conventional monocrystalline CBN (MCBN ones, longer service life is obtained for the brazed BCBN wheels.

  7. Wear Behavior of a NiCr/AgVO3 Self-Lubricating Composite

    Institute of Scientific and Technical Information of China (English)

    Wenting ZHANG; Lingzhong DU; Hao LAN; Chuanbing HUANG; Weigang ZHANG

    2013-01-01

    NiCr/AgVO3 self-lubricating composite was prepared by powder cold-pressed method with the NiCr alloy as the matrix and 10 wt.% additive of AgVO3 as solid lubricant.The AgVO3 additive powder was synthesized by the precipitation method which exhibits a melting point of 460 ℃.Microstructure,phase composition and thermal properties of the AgVO3 powder,as well as the composite of NiCr/AgVO3 were analyzed using scanning electron microscopy (SEM),transmission electron microscopy (TEM),X-ray diffraction (XRD) and differential scanning calorimeter (DSC).The friction and wear behavior of the specimens from room temperature (R.T.)to 800 ℃ was evaluated using a ball-on-disk tribometer and 3D white light interference (WLI).The results showed that the friction coefficient of this material under atmosphere decreases with temperature increasing from R.T.to 800 ℃.However,the wear rate firstly increases from R.T.to 200 ℃,almost remains stable from 200 ℃ to 600 ℃,and then decreases with further increasing the temperature up to 800 ℃.It is also found that the prepared composite materials show a better frictional behavior than NiCr alloy over the whole range of temperatures,which is mainly attributed to solid lubrication of AgVO3 exhibiting a lamella-slip structure at temperatures below 460 ℃ and forms liquid-film at elevated temperatures above the melting point.

  8. Wear Behavior and Mechanism of H13 Steel in Different Environmental Media

    Science.gov (United States)

    Li, Xinxing; Zhou, Yin; Cao, Huan; Li, Yixian; Wang, Lan; Wang, Shuqi

    2016-10-01

    Sliding wear tests were performed for H13 steel in atmosphere, distilled water, 3.5% NaCl, and 5% NaOH water solutions under various loads on a pin-on-disk wear tester. The results showed that for different environmental media, the wear rate of H13 steel in atmosphere was the maximum and that in 3.5% NaCl solution was the minimum. The maximum wear rate in atmosphere was caused by a larger quantity of heat produced in the friction process. In this case, the adhesive wear prevailed. In three wet environments, the mild wear prevailed due to the good lubrication and cooling capacity of media as well as corrosion product film on worn surface. In distilled water, the wear mechanism was a typical fatigue wear. On the other hand, in 3.5% NaCl and 5% NaOH solutions, corrosive wear prevailed. The minimum wear rate in 3.5% NaCl solution was attributed to the protective function of corrosion product film. On the contrary, noncompact corrosion product film in 5% NaOH solution resulted in higher wear rate.

  9. Friction and wear behavior of steam-oxidized ferrous PM compacts

    Energy Technology Data Exchange (ETDEWEB)

    Raj, P. Philomen-D-Anaand; GopalaKrishna, A. [Dept. of Mechanical Engineering, Jawaharlal Nehru Technological University, Kakinada (India); Palaniradja, K [Dept. of Mechanical Engineering, Pondicherry Engineering College, Pondicherry (India)

    2016-10-15

    This study determines density effect by assessing sintering temperature and graphite content on the dry sliding wear characteristics of steam-treated iron materials using a pin-on-disk wear test. The specimens were prepared from atomized premixed iron base powders and contained 0.1 to 1.0 wt.% carbon compacted at different densities (5.9 g/cc to 6.8 g/cc). The specimens were sintered for 1 h at different sintering temperatures (1090°C to 1130°C), and then subjected to continuous steam treatment at 540°C for 95 min through in situ Powder metallurgy (PM) technique. Steam treatment was proposed to improve the wear performances of the components of PM. Wear tests were conducted using a pin-on-disk-type machine. Load ranged from 20 N to 60 N. Sliding distance and sliding velocity of 312 m and 0.26 m/s, respectively, were adopted for all tests. Scanning electron microscope was used to analyze wear surface. Increased density and graphite content reduced the wear rate of steam-treated materials. Hardness increased with increasing graphite content. Wear mechanism, wear rate map, and wear maps were drawn for the test result data. Wear transition map identified mild, severe, and ultra-severe wear regimes as functions of applied load.

  10. Dry sliding wear behavior of Ti-6Al-4V alloy in air

    Institute of Scientific and Technical Information of China (English)

    刘勇; 杨德庄; 武万良; 杨士勤

    2002-01-01

    The dry sliding wear properties of Ti-6Al-4V alloy sliding against GCr15 steel under different velocities(between 0.2 and 1.2 m/s)and applied loads(from 30 to 90 N)were tested using a pin-on-disk tester in air. The wear occurred on both surfaces of the tested couplings. The wear rate of the Ti-6Al-4V alloy ranged from 23.0 to 123.8 mg/km. The wear of Ti-6Al-4V samples was in severe wear. The wear rate of Ti-6Al-4V samples increased with the increasing of load and shows a minimum on the curves of wear rate versus sliding velocity. SEM morphologies of worn surfaces and debris were observed. Phases in the debris were analyzed by means of XRD spectra.

  11. Evaluation of sliding wear behavior of graphite particle-containing magnesium alloy composites

    Institute of Scientific and Technical Information of China (English)

    QI Qing-ju

    2006-01-01

    The influence of graphite particle content on the friction and wear characteristics of AZ91 magnesium alloy matrix composite was studied. The results show that the wear resistances of graphite-containing composite are much better than those of the matrix under the test conditions. The anti-wear ability of magnesium alloy composite is improved substantially with the increase of the graphite content from 5% to 20%, and both wear mass loss and coefficient of friction are decreased to low level. Different wear mechanisms operate at different sliding stages. A continuous black lubricating film forms progressively on the worn surface along sliding, which effectively limits the direct interaction between the composite tribosurface and the counterpart, and also remarkably delays the transition from mild wear to severe wear for magnesium alloy composite.

  12. Effect of sintering temperature and boron carbide content on the wear behavior of hot pressed diamond cutting segments

    Directory of Open Access Journals (Sweden)

    Islak S.

    2015-01-01

    Full Text Available The aim of this study was to investigate the effect of sintering temperature and boron carbide content on wear behavior of diamond cutting segments. For this purpose, the segments contained 2, 5 and 10 wt.% B4C were prepared by hot pressing process carried out under a pressure of 35 MPa, at 600, 650 and 700 °C for 3 minutes. The transverse rupture strength (TRS of the segments was assessed using a three-point bending test. Ankara andesite stone was cut to examine the wear behavior of segments with boron carbide. Microstructure, surfaces of wear and fracture of segments were determined by scanning electron microscopy (SEM-EDS, and X-ray diffraction (XRD analysis. As a result, the wear rate decreased significantly in the 0-5 wt.% B4C contents, while it increased in the 5-10 wt.% B4C contents. With increase in sintering temperature, the wear rate decreased due to the hard matrix.

  13. Preparation, characterization and wear behavior of carbon coated magnesium alloy with electroless plating nickel interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Yan [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Academician Expert Office Workstation (Jiansheng Pan), Lin’an, Zhejiang Province (China); Feng, Kai, E-mail: fengkai@sjtu.edu.cn [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Academician Expert Office Workstation (Jiansheng Pan), Lin’an, Zhejiang Province (China); Guo, Xingwu [National Engineering Research Center of Light Alloys Net Forming (LAF), School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhou, Zhifeng [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Dong, Jie [National Engineering Research Center of Light Alloys Net Forming (LAF), School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Wu, Yixiong [Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240 (China); Academician Expert Office Workstation (Jiansheng Pan), Lin’an, Zhejiang Province (China)

    2015-02-01

    Highlights: • The carbon film with nickel interlayer (Ni + C coating) is deposited on GW83. • In Ni + C composite coating the carbon coating has good adhesion with the nickel interlayer. • The wear track of Ni + C coating is narrower compared to the bare one. • The wear resistance of GW83 is greatly improved by the Ni + C coating. - Abstract: Poor wear resistance of rare earth magnesium alloys has prevented them from wider application. In this study, composite coating (PVD carbon coating deposited on electroless plating nickel interlayer) is prepared to protect GW83 magnesium alloys against wear. The Ni + C composite coating has a dense microstructure, improved adhesion strength and hardness due to the effective support of Ni interlayer. The wear test result shows that the Ni + C composite coating can greatly prolong the wear life of the magnesium alloy. The wear track of the Ni + C coated magnesium alloy is obviously narrower and shows less abrasive particles as compared with the bare one. Abrasive wear is the wear mechanism of the coatings at the room temperature. In conclusion, the wear resistance of the GW83 magnesium alloy can be greatly improved by the Ni + C composite coating.

  14. Effect of cobalt content on wear and corrosion behaviors of electrodeposited Ni-Co/WC nano-composite coatings.

    Science.gov (United States)

    Amadeh, A; Ebadpour, R

    2013-02-01

    Metal-ceramic composite coatings are widely used in automotive and aerospace industries as well as micro-electronic systems. Electrodeposition is an economic method for application of these coatings. In this research, nickel-cobalt coatings reinforced by nano WC particles were applied on carbon steel substrate by pulse electrodeposition from modified Watts bath containing different amounts of cobalt sulphate as an additive. Saccharin and sodium dodecyl sulphate (SDS) were also added to electroplating bath as grain refiner and surfactant, respectively. The effect of cobalt content on wear and corrosion behavior of the coatings was investigated. Wear and corrosion properties were assessed by pin-on-disk and potentiodynamic polarization methods, respectively. Phase analysis was performed by X-ray diffraction (XRD) using CuK(alpha) radiation and the worn surfaces were studied by means of Scanning Electron Microscopy (SEM). The results showed that the addition of cobalt improved the wear resistance of the coatings. In the presence of 18 g/L cobalt in electrodeposition bath, the wear rate of the coating decreased to 0.002 mg/m and the coefficient of friction reduced to 0.695 while they were 0.004 mg/m and 0.77 in the absence of cobalt, respectively. This improvement in wear properties can be attributed to the formation of hcp phase in metallic matrix. Meanwhile, the corrosion resistance of the coatings slightly reduced because cobalt is more active metal with respect to nickel.

  15. Abrasive wear behavior of heat-treated ABC-silicon carbide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao Feng; Lee, Gun Y.; Chen, Da; Ritchie, Robert O.; De Jonghe, Lutgard C.

    2002-06-17

    Hot-pressed silicon carbide, containing aluminum, boron, and carbon additives (ABC-SiC), was subjected to three-body and two-body wear testing using diamond abrasives over a range of sizes. In general, the wear resistance of ABC-SiC, with suitable heat treatment, was superior to that of commercial SiC.

  16. Effect of temperature on friction and wear behavior of CuO-zirconia composites

    NARCIS (Netherlands)

    Valefi, Mahdiar; de Rooij, Matthias B.; Schipper, Dirk J.; Winnubst, Aloysius J.A.

    2012-01-01

    Results of wear tests using an alumina ball sliding against 5 wt% copper oxide doped tetragonal zirconia polycrystalline (CuO-TZP) ceramics are reported as a function of temperature up to 700 °C. The specific wear rate and friction coefficient are strongly dependent on temperature. Below a critical

  17. Effect of temperature on friction and wear behavior of CuO-zirconia composites

    NARCIS (Netherlands)

    Valefi, M.; Rooij, de M.B.; Schipper, D.J.; Winnubst, A.J.A.

    2012-01-01

    Results of wear tests using an alumina ball sliding against 5 wt% copper oxide doped tetragonal zirconia polycrystalline (CuO-TZP) ceramics are reported as a function of temperature up to 700 °C. The specific wear rate and friction coefficient are strongly dependent on temperature. Below a critical

  18. Wear Behavior of Ceramic CAD/CAM Crowns and Natural Antagonists

    Directory of Open Access Journals (Sweden)

    Ella A. Naumova

    2017-02-01

    Full Text Available Objective: Evaluation of wear behavior of computer-aided design/computer-aided manufacturing (CAD/CAM crowns from various restorative materials and natural antagonists. Method: Full CAD/CAM crowns fabricated with nanoceramic resin (Lava Ultimate (LU, a glass ceramic in a resin interpenetrating matrix (Vita Enamic (VE and a lithium silicate reinforced ceramic enriched with zirconia (Vita Suprinity (VS were cemented on human molars. The crown and antagonists were subjected to simulated chewing. 3D data sets, before and after the chewing simulation, were generated and matched. Occlusal surface roughness, vertical and volume loss of the crowns and antagonists were analyzed. Results: Crown roughness was significantly different between the LU and VE groups after chewing simulation. Crown vertical loss differed in all groups. The highest crown volume loss was found in the LU group, and the lowest in the VE group. Comparisons between the LU and VE groups and the LU and VS groups were significantly different. The highest antagonist volume loss was reached in the VE group, the lowest was in the LU group. Conclusion: Roughness increased after chewing simulation. LU crowns are the most natural antagonist-friendly; these were the most susceptible to vertical and volume loss. Of the tested materials, the VE crowns are the most stable regarding occlusion.

  19. Friction and wear behavior of nitrogen-doped ZnO thin films deposited via MOCVD under dry contact

    Directory of Open Access Journals (Sweden)

    U.S. Mbamara

    2016-06-01

    Full Text Available Most researches on doped ZnO thin films are tilted toward their applications in optoelectronics and semiconductor devices. Research on their tribological properties is still unfolding. In this work, nitrogen-doped ZnO thin films were deposited on 304 L stainless steel substrate from a combination of zinc acetate and ammonium acetate precursor by MOCVD technique. Compositional and structural studies of the films were done using Rutherford Backscattering Spectroscopy (RBS and X-ray Diffraction (XRD. The frictional behavior of the thin film coatings was evaluated using a ball-on-flat configuration in reciprocating sliding under dry contact condition. After friction test, the flat and ball counter-face surfaces were examined to assess the wear dimension and failure mechanism. Both friction behavior and wear (in the ball counter-face were observed to be dependent on the crystallinity and thickness of the thin film coatings.

  20. Microstructure and Wear Behavior of CoCrFeMnNbNi High-Entropy Alloy Coating by TIG Cladding

    Directory of Open Access Journals (Sweden)

    Wen-yi Huo

    2015-01-01

    Full Text Available Alloy cladding coatings are widely prepared on the surface of tools and machines. High-entropy alloys are potential replacements of nickel-, iron-, and cobalt-base alloys in machining due to their excellent strength and toughness. In this work, CoCrFeMnNbNi HEA coating was produced on AISI 304 steel by tungsten inert gas cladding. The microstructure and wear behavior of the cladding coating were studied by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometer, microhardness tester, pin-on-ring wear tester, and 3D confocal laser scanning microscope. The microstructure showed up as a nanoscale lamellar structure matrix which is a face-centered-cubic solid solution and niobium-rich Laves phase. The microhardness of the cladding coating is greater than the structure. The cladding coating has excellent wear resistance under the condition of dry sliding wear, and the microploughing in the worn cladding coating is shallower and finer than the worn structure, which is related to composition changes caused by forming the nanoscale lamellar structure of Laves phase.

  1. Effect of La2O3 Addition on Microstructure and Wear Behavior of Electrospark Deposited Ni-BASED Coatings

    Science.gov (United States)

    Yuxin, Gao; Jian, Yi

    2013-12-01

    La2O3 doped Ni-based coatings have been prepared by electrospark deposition technique. The effect of La2O3 on the microstructure, hardness and wear behavior of the as-prepared Ni-based coatings is investigated by using X-ray diffractometer, scanning electron microscope, wear tribometer and Vickers hardness tester. Results indicates that the microstructure, hardness and wear resistance of La2O3 doped Ni-based coatings are effectively improved as compared to the undoped one, and the coating with the addition of 2.5 wt.% La2O3 shows the optimal improvement effects. The addition of La2O3 can reduce the defects, refine grains and increase hardness of the coating, which can inhibit the nucleation and propagation of cracking, consequently resist cutting and fracture during the wear process. Moreover, the addition of La2O3 leads to changes in abrasion mechanism of the coatings, and the reasons resulting in different abrasion mechanisms are discussed.

  2. Structure and sliding wear behavior of 321 stainless steel/Al composite coating deposited by high velocity arc spraying technique

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-xiong; XU Bin-shi; LIU Yan; LIANG Xiu-bing; XU Yi

    2008-01-01

    A typical 321 stainless steel/aluminum composite coating (321/Al coating) was prepared by high velocity arc spraying technique (HVAS) with 321 stainless steel wire as the anode and aluminum wire as the cathode.The traditional 321 stainless steel coating was also prepared for comparison.Tribological properties of the coatings were evaluated with the ring-block wear tester under different conditions.The structure and worn surface of the coatings were analyzed by scanning electron microscopy (SEM),X-ray diffractometry (XRD) and energy dispersion spectroscopy (EDS).The results show that,except for aluminum phase addition in tne 321/Al coating,no other phases are created compared with the 321 coating.However,due to the addition of aluminum,the 321/Al coating forms a type of "ductile/hard phases inter-deposited" structure and performs quite different tribological behavior.Under the dry sliding condition,the anti-wear property of 321/Al coating is about 42% lower than that of 321 coating.Butunder the oil lubricated conditions with or without 32h oil-dipping pretreatment,the anti-wear property of 321/Al coating is about 9% and 5% higher than that of 321 coating,respectively.The anti-wear mechanism of the composite coating is mainly relevant to the decrease of oxide impurities and the strengthening action resulted from the "ductile/hard phases inter-deposited" coating structure.

  3. Quantifying Cutting and Wearing Behaviors of TiN- and CrNCoated AISI 1070 Steel

    Directory of Open Access Journals (Sweden)

    Ahmet Cakan

    2008-11-01

    Full Text Available Hard coatings such as titanium nitride (TiN and chromium nitride (CrN are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM, line scan analyses and X-ray diffraction (XRD. The wear properties of TiN- and CrNcoated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

  4. Quantifying Cutting and Wearing Behaviors of TiN- and CrNCoated AISI 1070 Steel.

    Science.gov (United States)

    Cakan, Ahmet; Ozkaner, Vedat; Yildirim, Mustafa M

    2008-11-05

    Hard coatings such as titanium nitride (TiN) and chromium nitride (CrN) are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP) technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM), line scan analyses and X-ray diffraction (XRD). The wear properties of TiN- and CrNcoated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples.

  5. Wear Behavior of Fiber Laser Textured TiN Coatings in a Heavy Loaded Sliding Regime

    Directory of Open Access Journals (Sweden)

    Daniele Ugues

    2012-11-01

    Full Text Available In heavy loaded mating components, such as sliders and sliding bearings, guaranteeing the efficiency of lubricant films for long times during severe service conditions is very complicated. In this work, the benefits deriving from the use of fiber laser sources for surface texturing of very thin TiN coatings in severe wear working conditions were demonstrated. Evaluations of the laser textured dimples shape, geometry and density are given. Wear performance of the fiber laser textured surfaces was evaluated in discontinuous oil lubricated conditions with a flat contact. High normal load and low sliding speed were applied. Comparison tests were also performed on commercial TiN and WC/C coatings. In terms of average wear volume and maximum wear depth, Laser Surface Texturing of TiN provided respectively a 70% and a 45% reduction if compared to plain TiN. If compared to WC/C the wear resistance gains were lower but LST TiN maintained such benefits for longer wear runs. SEM analysis also revealed that the laser interaction provided a localized thermal cracking to the TiN coating. However, the sliding action caused very limited and localized coating fragmentation or delamination.

  6. The Effect of Time Variation on the Wear Sliding Behavior of Composites

    Directory of Open Access Journals (Sweden)

    Wafaa M. Salih

    2009-01-01

    Full Text Available Composites materials are widely used in all industries all over the world, replacing many other engineering materials. Reasons for such popularity are many, among such, are their physical and mechanical properties in addition to the simplicity of their manufacturing processes. Machine elements that are made of polymeric materials are usually exposed to different causes of failure such as wear. The time effect on the wear behaviour of some composite materials (polyester-commercially fiber reinforcement named (E-glass was studied. In this study four type of composite different in number of layers, it had (3-6-9-12 layers (Wear volume 0.48, 0.41, 0.71 and 0.78 respectively. All experiments were conducted under dry condition. Preliminary results show the wear volume increases for all examined composites, as the statically applied load increases. Fourth type has the highest wear resistance, then third type and lastly first type. The wear volume increases for all examined composites, varied of time increases.

  7. Influence of oil and water media on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel

    Institute of Scientific and Technical Information of China (English)

    REN Ping-di; CHEN Guang-xiong; ZHU Min-hao; ZHOU Zhong-rong

    2004-01-01

    A series of fretting test were carried out using a DELTA PLINT testing system to study the influence of hydraulic oil and water on fretting behaviour of AISI 52100 steel rubbing against AISI 1045 steel. The test result shows that media hydraulic oil and water have a distinct influence on fretting behaviour of the tested materials. Medium water can lead to shifting of the partial slip regime in the fretting map from a larger displacement amplitude toward a smaller one and enlargement of the mixed slip regime, in comparison with that in ambient atmosphere. While medium hydraulic oil can result in shifting of the partial slip regime from a smaller displacement amplitude toward a larger one. In the gross slip regime, hydraulic oil and water play a positive role as lubrication media. They can clearly decrease the fretting friction coefficient between AISI 52100 and AISI 1045. The test result also demonstrates that this lubrication effect will get better with increasing displacement amplitude and that hydraulic oil is better than water for lubrication. SEM observation of the wear scars displays that the fretting wear mainly results from abrasive wear and delamination of the fretted materials when using these two kinds of substances as lubrication media.

  8. Ti6Al4V Blade Wear Behavior During High-Speed Rubbing with NiAl-hBN Abradable Seal Coating

    Science.gov (United States)

    Xue, Weihai; Gao, Siyang; Duan, Deli; Zhang, Jiaping; Liu, Yang; Li, Shu

    2016-12-01

    The high-speed rubbing wear behavior between a Ti6Al4V blade and a NiAl-hBN seal coating was studied with a high-speed rub test rig. Blade wear behavior, which had not received enough attentions, was the key concern of this study. The rub tests conducted at different linear speeds and single-pass depths indicated that although wear distance was constant and rub forces decreased at high linear speed, blade wear increased with the increment of linear speed when single-pass depth was invariable. According to scanning electron microscopy, x-ray diffraction, electron probe microanalysis and microhardness analyses of the wear scars, different blade and coating wear mechanisms were observed when rubbed at different linear speeds. Remarkably, when rubbing was done at high linear speed, there was severe blade oxidation with the generation of oxidation layer full of cracks and high-hardness transfer layer in the coating wear scar, and these were identified as reasons of aggravated blade wear.

  9. Ti6Al4V Blade Wear Behavior During High-Speed Rubbing with NiAl-hBN Abradable Seal Coating

    Science.gov (United States)

    Xue, Weihai; Gao, Siyang; Duan, Deli; Zhang, Jiaping; Liu, Yang; Li, Shu

    2017-02-01

    The high-speed rubbing wear behavior between a Ti6Al4V blade and a NiAl-hBN seal coating was studied with a high-speed rub test rig. Blade wear behavior, which had not received enough attentions, was the key concern of this study. The rub tests conducted at different linear speeds and single-pass depths indicated that although wear distance was constant and rub forces decreased at high linear speed, blade wear increased with the increment of linear speed when single-pass depth was invariable. According to scanning electron microscopy, x-ray diffraction, electron probe microanalysis and microhardness analyses of the wear scars, different blade and coating wear mechanisms were observed when rubbed at different linear speeds. Remarkably, when rubbing was done at high linear speed, there was severe blade oxidation with the generation of oxidation layer full of cracks and high-hardness transfer layer in the coating wear scar, and these were identified as reasons of aggravated blade wear.

  10. Optimization of wear behavior of electroless Ni-P-W coating under dry and lubricated conditions using genetic algorithm (GA

    Directory of Open Access Journals (Sweden)

    Arkadeb Mukhopadhyay

    2016-12-01

    Full Text Available The present study aims to investigate the tribological behavior of Ni-P-W coating under dry and lubricated condition. The coating is deposited onto mild steel (AISI 1040 specimens by the electroless method using a sodium hypophosphite based alkaline bath. Coating characterization is done to investigate the effect of microstructure on its performance. The change in microhardness is observed to be quite significant after annealing the deposits at 400°C for 1h. A pin–on–disc type tribo-tester is used to investigate the tribological behavior of the coating under dry and lubricated conditions. The experimental design formulation is based on Taguchi’s orthogonal array. The design parameters considered are the applied normal load, sliding speed and sliding duration while the response parameter is wear depth. Multiple regression analysis is employed to obtain a quadratic model of the response variables with the main design parameters under considerations. A high value of coefficient of determination of 95.3% and 87.5% of wear depth is obtained under dry and lubricated conditions, respectively which indicate good correlation between experimental results and the multiple regression models. Analysis of variance at a confidence level of 95% shows that the models are statistically significant. Finally, the quadratic equations are used as objective functions to obtain the optimal combination of tribo testing parameters for minimum wear depth using genetic algorithm (GA.

  11. Effect of carbon nanotube addition on the wear behavior of basalt/epoxy woven composites.

    Science.gov (United States)

    Kim, M T; Rhee, K Y; Lee, B H; Kim, C J

    2013-08-01

    The effect of acid-treated carbon nanotube (CNT) addition on the wear and dynamic mechanical thermal properties of basalt/epoxy woven composites was investigated in this study. Basalt/CNT/epoxy composites were fabricated by impregnating woven basalt fibers into epoxy resin mixed with 1 wt% CNTs which were acid-treated. Wear and DMA (dynamic mechanical analyzer) tests were performed on basalt/epoxy composites and basalt/CNT/epoxy composites. The results showed that the addition of the acid-treated CNTs improved the wear properties of basalt/epoxy woven composites. Specifically, the friction coefficient of the basalt/epoxy composite was stabilized in the range of 0.5-0.6 while it fell in the range of 0.3-0.4 for basalt/CNT/epoxy composites. The wear volume loss of the basalt/CNT/epoxy composites was approximately 68% lower than that of the basalt/epoxy composites. The results also showed that the glass transition temperature of basalt/CNT/epoxy composites was higher than that of basalt/epoxy composites. The improvement of wear properties of basalt/epoxy composites by the addition of acid-treated CNTs was caused by the homogeneous load transfer between basalt fibers and epoxy matrix due to the reinforcement of CNTs.

  12. Influence of Eta-Phase on Wear Behavior of WC-Co Carbides

    Directory of Open Access Journals (Sweden)

    A. Formisano

    2016-01-01

    Full Text Available Cemented carbides, also known as Widia, are hard metals produced by sintering process and widely used in mechanical machining. They show high cutting capacity and good wear resistance; consequently, they result to be excellent materials for manufacturing cutting tools and sandblast nozzles. In this work, the wear resistance of WC-Co carbides containing Eta-phase, a secondary phase present in the hard metals when a carbon content deficiency occurs, is analyzed. Different mixtures of carbide are prepared and sintered, with different weight percentages of carbon, in order to form Eta-phase and then analyze how the carbon content influences the wear resistance of the material. This characterization is carried out by abrasive wear tests. The test parameters are chosen considering the working conditions of sandblast nozzles. Additional information is gathered through microscopic observations and the evaluation of hardness and microhardness of the different mixtures. The analyses highlight that there is a limit of carbon content below which bad sintering occurs. Considering the mixtures without these sintering problems, they show a wear resistance depending on the size and distribution of the Eta-phase; moreover, the one with high carbon content deficiency shows the best performance.

  13. Influence of composition on friction-wear behavior of composite materials reinforced by brass fibers

    Institute of Scientific and Technical Information of China (English)

    JIA Xian; LING Xiaomei

    2003-01-01

    In the study, for the composite materials reinforced by brass fibers, the influence of dominant ingredients, such as organic adhesion agent, cast iron debris, brass fiber, and graphite powder, on the friction-wear characteristics was investigated. The friction-wear experiment was carried out on the block-on-ring tribometer MM200. The worn surfaces of the friction pair consisting of the composite materials and grey cast iron HT200 under dry sliding friction were examined using scanning electron microscope (SEM), energy dispersive analysis (EDX) and differential thermal analysis-thermogravimetric analysis (DTA-TAG). The experimental results showed that the friction coefficient and the wear loss of the composite material increase obviously with the increase of cast iron debris content, but decrease obviously with the increase of graphite powder content, and increase a little when the mass fraction of brass fiber was over 19%, and the orientation of brass fiber has obvious influence on friction-wear property. When the mass fraction of organic adhesion agent was about 10-11%, the composite materials have an excellent friction-wear performance. The friction heat can pyrolyze organic ingredient in worn surface layer.

  14. Sliding wear behavior of E-glass-epoxy/MWCNT composites: An experimental assessment

    Directory of Open Access Journals (Sweden)

    Ravindranadh Bobbili

    2016-03-01

    Full Text Available This investigation has evaluated the sliding wear properties of E-glass-epoxy/MWCNT (multiwalled carbon nanotube composite and Epoxy/MWCNT composite. Four different reinforcements (0, 0.5,1 and 1.5 wt % of MWCNTs are dispersed into an epoxy resin. Design of experiments (DOE and Analysis of variance (ANOVA are employed to understand the relationship between control factors (Percentage of reinforcement, Sliding distance, Sliding velocity and Normal load and response measures (specific wear rate and friction coefficient. The control variables such as sliding distance (300, 600, 900 and 1200 m and normal loads of 10, 15, 20 and 25 N and at sliding velocities of 1, 2, 3 and 4 m/s are chosen for this study. It is observed that that the specific wear rate and friction coefficient can be reduced by the addition of MWCNTs. Scanning electron microscopy (SEM is used to observe the worn surfaces of the samples. Compared with neat epoxy, the composites with MWCNTs showed a lower mass loss, friction coefficient and wear rate and these parameters decreased with the increase of MWCNT percentage. Microscopic investigation of worn out sample fracture surface has revealed that fiber debonding happens when the stresses at the fiber matrix interface exceeds the interfacial strength, causing the fiber to debond from the matrix. The optimum control variables have been derived to reduce both wear and friction coefficient of composites.

  15. Modeling of wear behavior of Al/B{sub 4}C composites produced by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Sahin, Ismail; Bektas, Asli [Gazi Univ., Ankara (Turkey). Dept. of Industrial Design Engineering; Guel, Ferhat; Cinci, Hanifi [Gazi Univ., Ankara (Turkey). Dept. of Materials and Metallurgy Engineering

    2017-06-01

    Wear characteristics of composites, Al matrix reinforced with B{sub 4}C particles percentages of 5, 10,15 and 20 produced by the powder metallurgy method were studied in this study. For this purpose, a mixture of Al and B{sub 4}C powders were pressed under 650 MPa pressure and then sintered at 635 C. The analysis of hardness, density and microstructure was performed. The produced samples were worn using a pin-on-disk abrasion device under 10, 20 and 30 N load through 500, 800 and 1200 mesh SiC abrasive papers. The obtained wear values were implemented in an artificial neural network (ANN) model having three inputs and one output using feed forward backpropagation Levenberg-Marquardt algorithm. Thus, the optimum wear conditions and hardness values were determined.

  16. Friction and wear behavior of single-crystal silicon carbide in sliding contact with various metals

    Science.gov (United States)

    Miyoshi, K.; Buckley, D. H.

    1978-01-01

    Sliding friction experiments were conducted with single-crystal silicon carbide in contact with various metals. Results indicate the coefficient of friction is related to the relative chemical activity of the metals. The more active the metal, the higher the coefficient of friction. All the metals examined transferred to silicon carbide. The chemical activity of the metal and its shear modulus may play important roles in metal-transfer, the form of the wear debris and the surface roughness of the metal wear scar. The more active the metal, and the less resistance to shear, the greater the transfer to silicon carbide and the rougher the wear scar on the surface of the metal. Hexagon-shaped cracking and fracturing formed by cleavage of both prismatic and basal planes is observed on the silicon carbide surface.

  17. Wear Behavior of Aluminium Metal Matrix Composite Prepared from Industrial Waste

    Directory of Open Access Journals (Sweden)

    L. Francis Xavier

    2016-01-01

    Full Text Available With an increase in the population and industrialization, a lot of valuable natural resources are depleted to prepare and manufacture products. However industrialization on the other hand has waste disposal issues, causing dust and environmental pollution. In this work, Aluminium Metal Matrix Composite is prepared by reinforcing 10 wt% and 20 wt% of wet grinder stone dust particles an industrial waste obtained during processing of quarry rocks which are available in nature. In the composite materials design wear is a very important criterion requiring consideration which ensures the materials reliability in applications where they come in contact with the environment and other surfaces. Dry sliding wear test was carried out using pin-on-disc apparatus on the prepared composites. The results reveal that increasing the reinforcement content from 10 wt% to 20 wt% increases the resistance to wear rate.

  18. a Study on the Fretting Fatigue Life of Zircaloy Alloys

    Science.gov (United States)

    Kwon, Jae-Do; Park, Dae-Kyu; Woo, Seung-Wan; Chai, Young-Suck

    Studies on the strength and fatigue life of machines and structures have been conducted in accordance with the development of modern industries. In particular, fine and repetitive cyclic damage occurring in contact regions has been known to have an impact on fretting fatigue fractures. The main component of zircaloy alloy is Zr, and it possesses good mechanical characteristics at high temperatures. This alloy is used in the fuel rod material of nuclear power plants because of its excellent resistance. In this paper, the effect of the fretting damage on the fatigue behavior of the zircaloy alloy is studied. Further, various types of mechanical tests such as tension and plain fatigue tests are performed. Fretting fatigue tests are performed with a flat-flat contact configuration using a bridge-type contact pad and plate-type specimen. Through these experiments, it is found that the fretting fatigue strength decreases by about 80% as compared to the plain fatigue strength. Oblique cracks are observed in the initial stage of the fretting fatigue, in which damaged areas are found. These results can be used as the basic data for the structural integrity evaluation of corrosion-resisting alloys considering the fretting damages.

  19. Effect of Contact Load on the Fretting Fatigue of Steel Wire under Alkaline Corrosive Environment%碱性腐蚀环境下接触载荷对钢丝微动疲劳行为的影响

    Institute of Scientific and Technical Information of China (English)

    赵维建; 张德坤; 张泽锋; 王崧全; 王世博

    2012-01-01

    The fretting fatigue tests of the mine steel wires under alkaline corrosive environment are performded on a self - made fretting fatigue test machine. The fretting fatigue behaviors of steel wires with a strain ration of 0.8 are studied under different contact loads. The damage mechanisms of steel wires are analyzed by the optical microscopy and scanning electron microscopy. The results indicate that the evolution of friction coefficients of steel wires can be divided into four stages, i.e. , running- in period, ascending period, declining period and stable period. The fretting regime of steel wires is gross slip regime under the four different contact loads. Corrosive wear, abrasive wear, fatigue wear and plastic deformation are the main wear mechanisms. The fatigue lifetime of the fretted steel wires is inversely proportional to the wear depth. Fatigue fracture surface can be divided into three regions, i.e. ,fatigue source region, crack propagation region and transient break regions.%以矿用钢丝为研究对象,在自制的钢丝微动疲劳试验机上开展钢丝在碱性腐蚀环境下的微动疲劳试验,考察钢丝在应变比为0.8时不同接触载荷下钢丝的微动运行特性,并用光学显微镜和扫描电子显微镜观察钢丝的磨痕和断口形貌,分析其微动磨损和疲劳断裂机理.结果表明:不同接触载荷下钢丝的摩擦系数具有相同的变化趋势,均可以分为4个阶段:跑合期、上升期、下降期和稳定期;4种不同接触载荷下钢丝摩擦副均运行于滑移状态,磨损机制以腐蚀磨损、磨粒磨损、疲劳磨损和塑性变形为主;钢丝疲劳寿命与磨损量成反比,疲劳断口可分为3个区:疲劳源区、扩展区和瞬断区.

  20. Investigation on Friction and Wear of Cold Rolled High Strength Steel against an AISI52100 Counterpart

    Directory of Open Access Journals (Sweden)

    Jiwon Hur

    2017-03-01

    Full Text Available This article investigates the friction and wear of cold rolled high strength steel at various displacement amplitudes. Reciprocal sliding tests are carried out using a ball-on-flat testing apparatus. The tangential force occurring at the contact surface between a high strength steel specimen and an AISI52100 ball is measured during the tests. After each test, the worn surface profile on the steel specimen is determined. Experimental results show that the ratio of the maximum tangential to the normal force remains at 0.7 after an initial rapid increase, and the ratio does not greatly change according to the imposed displacement amplitudes (in the range of 0.05 mm and 0.3 mm. The wear volume loss on the steel specimen increases according to the number of cycles. It is determined that the wear rate of the specimen changes with respect to the imposed displacement amplitude. That is, the wear rate rapidly increases within the displacement amplitude range of 0.05 mm to 0.09 mm, while the wear rate gradually increases when the displacement amplitude is greater than 0.2 mm. The obtained results provide the friction and wear behaviors of cold rolled high strength steel in fretting and reciprocal sliding regimes.

  1. Sliding wear behaviors of electrodeposited Ni composite coatings containing micrometer and nanometer Cr particles

    Institute of Scientific and Technical Information of China (English)

    ZHAO Guo-gang; ZHOU Yue-bo; ZHANG Hai-jun

    2009-01-01

    Micrometer and nanometer Cr particles were co-deposited with Ni by electroplating from a nickel sulfate bath containing a certain content of Cr particles. Cr microparticles are in a size range of 1-5 (m and Cr nanoparticles have an average size of 40 nm. The friction and the wear performance of the co-deposited Ni-Cr composite coatings were comparatively evaluated by sliding against Si3N4 ceramic balls under non-lubricated conditions. It is found that the incorporation of Cr particles enhances the microhardness and wear resistance of Ni coatings. The wear resistance of Ni composite coating containing Cr nanoparticles is higher than that of the Ni composite coating containing Cr microparticles with a comparable Cr particle content. The co-deposition of smaller nanometer Cr particles with Ni effectively reduces the size of Ni crystals and significantly increases the hardness of the composite coatings due to grain-refinement strengthening and dispersion-strengthening, resulting in a significant improvement of wear resistance of the Ni-Cr nanocomposite coatings.

  2. Combined effects of fretting and pollutant particles on the contact resistance of the electrical connectors

    Directory of Open Access Journals (Sweden)

    Zhigang Kong

    2017-06-01

    Full Text Available Usually, when electrical connectors operate in vibration environments, fretting will be produced at the contact interfaces. In addition, serious environmental pollution particles will affect contact resistance of the connectors. The fretting will worsen the reliability of connectors with the pollutant particles. The combined effects of fretting and quartz particles on the contact resistance of the gold plating connectors are studied with a fretting test system. The results show that the frequencies have obvious effect on the contact resistance. The higher the frequency, the higher the contact resistance is. The quartz particles cause serious wear of gold plating, which make the nickel and copper layer exposed quickly to increase the contact resistance. Especially in high humidity environments, water supply certain adhesion function and make quartz particles easy to insert or cover the contact surfaces, and even cause opening resistance.

  3. Fretting corrosion of CoCr alloy: Effect of load and displacement on the degradation mechanisms.

    Science.gov (United States)

    Bryant, Michael; Neville, Anne

    2017-02-01

    Fretting corrosion of medical devices is of growing concern, yet, the interactions between tribological and electrochemical parameters are not fully understood. Fretting corrosion of CoCr alloy was simulated, and the components of damage were monitored as a function of displacement and contact pressure. Free corrosion potential (Ecorr), intermittent linear polarisation resistance and cathodic potentiostatic methods were used to characterise the system. Interferometry was used to estimate material loss post rubbing. The fretting regime influenced the total material lost and the dominant degradation mechanism. At high contact pressures and low displacements, pure corrosion was dominant with wear and its synergies becoming more important as the contact pressure and displacement decreased and increased, respectively. In some cases, an antagonistic effect from the corrosion-enhanced wear contributor was observed suggesting that film formation and removal may be present. The relationship between slip mechanism and the contributors to tribocorrosion degradation is presented.

  4. Tooth wear

    Directory of Open Access Journals (Sweden)

    Tušek Ivan

    2014-01-01

    surfaces. Attrition of teeth (attritio dentium represents teeth wear during mastication, friction on the tooth or teeth during parafunctional mandibular movements (bruxism, but without the abrasive effect. Dental erosion (erosio dentium or corrosive wear is a progressive, irreversible loss of dental hard tissue resulting from the effect of acids and /or chelation in the mouth, but without the participation of bacteria. Acids, of either exogenous or endogenous origin (peptic ulcer, gastritis, or bulimia, anoreksia nervosa, that come into the mouth can lead to different clinical manifestations of erosion depending on the time of exposure, the microstructure of teeth, buffering capacity, the amount of saliva and other factors. The changes are visible on the palatal surfaces of upper anterior teeth and, in severe cases, the lingual surfaces of posterior teeth. Occupational dental erosion occurs during exposure to industrial gases that contain hydrochloric or sulfuric acids, as well as the acids used in galvanizing and manufacture of battery and weapons. Due to the multifactorial nature of erosive tooth wear preventive measures must be applied taking into account chemical and biological factors as well as the patient's behavior associated with the etiology and pathogenesis of erosion. It is recommended to consume food and drinks that stimulate the secretion of large amounts of saliva base; to use neutral or alkaline mouthwash, and to chew sugar-free gum; to apply adequate oral hygiene (soft brushes, non-abrasive tooth paste, proper washing technique and not to consume aciding food and carbonated soft drinks and fizzy drinks in a great amount and frequently. It is necessary to apply preparations with high content of fluoride, and lubricant of tooth wear (powder CaF, CaF mixture and olive oil, and asset-based titanium tetrafluoride and casein-calcium phosphate. Commercial tooth paste that contains CPP-ACP (casein phosphopeptide-amorphous calcium phosphate and calcium phosphate

  5. Abrasive Wear Behaviors of Light-weight Austenitic Fe-24Mn-7Al-1C Steel and Mn13Cr2 Steel

    Institute of Scientific and Technical Information of China (English)

    Shi-guang PENG; Ren-bo SONG; Zhi-dong TAN; Chang-hong CAI; Ke GUO; Zhong-hong WANG

    2016-01-01

    The impact abrasive wear behaviors of light-weight austenitic Fe-24Mn-7Al-1C steel with increasing impact wear conditions were studied by comparing with the modified Hadfield (Mn13Cr2)steel.Wear tests were performed with the MLD-10 abrasive wear testing machine.Main parameters such as impact energy,impacting frequency and wear time were evaluated.To explore the abrasive wear behaviors under different impact energies,the parameters in-cluding mass loss,wear resistance and hardness were evaluated in detail.The microstructures of the steels were fur-ther analyzed using optical microscopy (OM),scanning electron microscopy (SEM),transmission electron micros-copy (TEM)and X-ray diffraction (XRD).Results showed that the light-weight austenitic Fe-24Mn-7Al-1C steel had a better wear resistance than Mn13Cr2 steel under the impact energy tested.The wear resistance of light-weight austenitic Fe-24Mn-7Al-1C steel was about 1.09-1.17 times as high as that of Mn13Cr2 steel under low and medi-um impact energy (0.5-2.0 J)conditions,and 1.41 times under high impact energy (4.0 J)condition.In Mn13Cr2 steel,the evolution of dislocation substructure with increasing impact energy showed typical stacking fault,interac-tion of twins and dislocations,as well as mechanical twins.The high work-hardening rate in Fe-24Mn-7Al-1C steel was caused by Taylor lattice and high density of dislocation tangles.

  6. Wear Behavior of Uncoated and Coated Tools under Complex Loading Conditions

    Directory of Open Access Journals (Sweden)

    M. Wieland

    2012-03-01

    Full Text Available In automotive industry crash relevant structures of the body in white are manufactured using the direct hot stamping process. Due to the high temperature difference between the hot blank and the cold tool surfaces and the relative movement between the blank and the tool surfaces during the forming operation, high thermal and mechanical loads are applied on the tool leading to excessive wear in terms of adhesion on the tool surfaces. One possibility to reduce wear of hot stamping tools is the application of tool coating systems. In the scope of this work uncoated and coated tools are characterized under complex loading conditions with respect to adhesive layer build-up.

  7. Effect of Ultrasonic Vibration on the Behavior of Antifriction and Wear Resistance of Al2O3/Al2O3 Ceramic Friction Pairs Under Oil Lubrication

    Science.gov (United States)

    Dong, X. Y.; Qiao, Y. L.; Zang, Y.; Cui, Q. S.

    The behavior of antifriction and wear resistance of Al2O3/Al2O3 ceramic friction pairs lubricated by four different lubrication oils under ultrasonic vibration was studied. The surface morphologies of wear scare was analyzed by metallographic microscope. The effect mechanism of ultrasonic vibration on frictional pairs under different lubrication oils was discussed. The studied results showed that, ultrasonic vibration would improve the behavior of antifriction and wear resistance of the Al2O3/Al2O3 ceramic friction pairs under various lubrication oils.The improving would be dramaticer when the viscosity of lubrication oil was low. Ultrasonic vibration decreased the friction coefficient and wear volume 12.9% and 38.7% respectively, when the lubrication oil was 6#,the viscosity of which is 39.77 mm2/s. When the lubrication oil was 150BS, the viscosity of which is 549.69 mm2/s, ultrasonic vibration made friction coefficient and wear volume decreased 4.6% and 11.6% respectively.The effect of ultrasonic vibration on the behavior of antifriction and wear resistance of Al2O3/Al2O3 ceramic friction pairs was determined by the formation and the destruction of oil film on the friction surface and the upward floatage created by ultrasonic vibration.

  8. Control of Fretting Fatigue

    Science.gov (United States)

    1977-07-01

    Minnesota ERNEST RABINOWICZ , Professor, D^i artment of Mechanical Engineering, Massachusetts Institute of Technology. Cambridge, Massachusetts...on Problem Definition; to E, Rabinowicz and C. H. Wells on Fundamentals; to J. A. Collins, D. W. Hoeppner and C. N. Rowe on Design Approaches; and to...its original interface [ Rabinowicz and Tabor (141)]; Burwell and Strang (33); and Archard (12)]. Consequently, a wear particle is transferred from

  9. Microstructure-Wear Resistance Correlation and Wear Mechanisms of Spark Plasma Sintered Cu-Pb Nanocomposites

    Science.gov (United States)

    Sharma, Amit Siddharth; Biswas, Krishanu; Basu, Bikramjit

    2014-01-01

    The dispersion of a softer phase in a metallic matrix reduces the coefficient of friction (COF), often at the expense of an increased wear rate at the tribological contact. To address this issue, unlubricated fretting wear tests were performed on spark plasma sintered Cu-Pb nanocomposites against bearing steel. The sintering temperature and the Pb content as well as the fretting parameters were judiciously selected and varied to investigate the role of microstructure (grain size, second-phase content) on the wear resistance properties of Cu-Pb nanocomposites. A combination of the lowest wear rate (~1.5 × 10-6 mm3/Nm) and a modest COF (~0.4) was achieved for Cu-15 wt pct Pb nanocomposites. The lower wear rate of Cu-Pb nanocomposites with respect to unreinforced Cu is attributed to high hardness (~2 to 3.5 GPa) of the matrix, Cu2O/Fe2O3-rich oxide layer formation at tribological interface, and exuding of softer Pb particles. The wear properties are discussed in reference to the characteristics of transfer layer on worn surface as well as subsurface damage probed using focused ion beam microscopy. Interestingly, the flash temperature has been found to have insignificant effect on the observed oxidative wear, and alternative mechanisms are proposed. Importantly, the wear resistance properties of the nanocomposites reveal a weak Hall-Petch-like relationship with grain size of nanocrystalline Cu.

  10. The Effect of Bias Voltage and Gas Pressure on the Structure, Adhesion and Wear Behavior of Diamond Like Carbon (DLC Coatings With Si Interlayers

    Directory of Open Access Journals (Sweden)

    Liam Ward

    2014-04-01

    Full Text Available In this study diamond like carbon (DLC coatings with Si interlayers were deposited on 316L stainless steel with varying gas pressure and substrate bias voltage using plasma enhanced chemical vapor deposition (PECVD technology. Coating and interlayer thickness values were determined using X-ray photoelectron spectroscopy (XPS which also revealed the presence of a gradient layer at the coating substrate interface. Coatings were evaluated in terms of the hardness, elastic modulus, wear behavior and adhesion. Deposition rate generally increased with increasing bias voltage and increasing gas pressure. At low working gas pressures, hardness and modulus of elasticity increased with increasing bias voltage. Reduced hardness and modulus of elasticity were observed at higher gas pressures. Increased adhesion was generally observed at lower bias voltages and higher gas pressures. All DLC coatings significantly improved the overall wear resistance of the base material. Lower wear rates were observed for coatings deposited with lower bias voltages. For coatings that showed wear tracks considerably deeper than the coating thickness but without spallation, the wear behavior was largely attributed to deformation of both the coating and substrate with some cracks at the wear track edges. This suggests that coatings deposited under certain conditions can exhibit ultra high flexible properties.

  11. Wear behavior of 2-1/4 Cr-1 Mo tubing against alloy 718 tube-support material in sodium-cooled steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, W L

    1983-05-01

    A series of prototypic steam generator 2-{1/4} Cr-1 Mo tube/alloy 718 tube support plate wear tests were conducted in direct support of the Westinghouse Nuclear Components Division -- Breeder Reactor Components Project Large Scale steam Generator design. The initial objective was to verify the acceptable wear behavior of softer, over-aged'' alloy 718 support plate material. For all interfaces under all test conditions, resultant wear damage was adhesive in nature with varying amounts of 2-{1/4} Cr-1 Mo tube material being adhesively transferred to the alloy 718 tube supports. Maximum tube wear depths exceeded the initially established design allowable limit of 127 {mu}m (.005 in.) at 17 of the 18 interfaces tested. A decrease in contact stresses produced acceptable tube wear depths below a readjusted maximum design allowable value of 381 {mu}m (.015 in.). Additional conservatisms associated with the simulation of a 40-year lifetime of rubbing in a one-week laboratory test provided further confidence that the 381 {mu}m maximum tube wear allowance would not be exceeded in service. Softer, over-aged'' alloy 718 material was found to produce slightly less wear damage on 2-{1/4} Cr-1 Mo tubing than fully age hardened material. Also, air formed oxide films on the alloy 718 reduced initial tube wear and delayed the onset of adhesive surface damage. However, at high surface stress levels, these films were not sufficiently stable to provide adequate long term protection from adhesive wear. The results of the present work and those of previous test programs suggest that the successful in-sodium tribological performance of 2-{1/4} Cr-1 Mo/alloy 718 rubbing couples is dependent upon the presence of lubricative surface films, such as oxides and/or surface reaction or deposition products. 11 refs., 13 figs., 4 tabs.

  12. Single cell FRET analysis for the identification of optimal FRET-pairs in Bacillus subtilis using a prototype MEM-FLIM system.

    Directory of Open Access Journals (Sweden)

    Ruud G J Detert Oude Weme

    Full Text Available Protein-protein interactions can be studied in vitro, e.g. with bacterial or yeast two-hybrid systems or surface plasmon resonance. In contrast to in vitro techniques, in vivo studies of protein-protein interactions allow examination of spatial and temporal behavior of such interactions in their native environment. One approach to study protein-protein interactions in vivo is via Förster Resonance Energy Transfer (FRET. Here, FRET efficiency of selected FRET-pairs was studied at the single cell level using sensitized emission and Frequency Domain-Fluorescence Lifetime Imaging Microscopy (FD-FLIM. For FRET-FLIM, a prototype Modulated Electron-Multiplied FLIM system was used, which is, to the best of our knowledge, the first account of Frequency Domain FLIM to analyze FRET in single bacterial cells. To perform FRET-FLIM, we first determined and benchmarked the best fluorescent protein-pair for FRET in Bacillus subtilis using a novel BglBrick-compatible integration vector. We show that GFP-tagRFP is an excellent donor-acceptor pair for B. subtilis in vivo FRET studies. As a proof of concept, selected donor and acceptor fluorescent proteins were fused using a linker that contained a tobacco etch virus (TEV-protease recognition sequence. Induction of TEV-protease results in loss of FRET efficiency and increase in fluorescence lifetime. The loss of FRET efficiency after TEV induction can be followed in time in single cells via time-lapse microscopy. This work will facilitate future studies of in vivo dynamics of protein complexes in single B. subtilis cells.

  13. Fretting fatigue behaviour of Ni-free high-nitrogen stainless steel in a simulated body fluid

    Directory of Open Access Journals (Sweden)

    Norio Maruyama, Sachiko Hiromoto, Eiji Akiyama and Morihiko Nakamura

    2013-01-01

    Full Text Available Fretting fatigue behaviour of Ni-free high-nitrogen steel (HNS with a yield strength of about 800 MPa, which was prepared by nitrogen gas pressurized electroslag remelting, was studied in air and in phosphate-buffered saline (PBS(-. For comparison, fretting fatigue behaviour of cold-rolled SUS316L steel (SUS316L(CR with similar yield strength was examined. The plain fatigue limit of HNS was slightly lower than that of SUS316L(CR although the former had a higher tensile strength than the latter. The fretting fatigue limit of HNS was higher than that of SUS316L(CR both in air and in PBS(-. A decrease in fatigue limit of HNS by fretting was significantly smaller than that of SUS316L(CR in both environments, indicating that HNS has better fretting fatigue resistance than SUS316L(CR. The decrease in fatigue limit by fretting is discussed taking into account the effect of friction stress due to fretting and the additional influences of wear, tribocorrosion and plastic deformation in the fretted area.

  14. Wear Behavior of the Lead-Free Tin Bronze Matrix Composite Reinforced by Carbon Nanotubes

    Science.gov (United States)

    Zeng, Jun; Fan, Huiqing; Wang, Yangli; Zhang, Siquan

    2011-12-01

    Copper-coated carbon nanotubes were prepared by the electroless plating route. The structure and component of copper/carbon tubes were characterized using a transmission electron microscope and energy dispersive spectrometer. The results show that the surface of the carbon tubes was covered by the copper particles. Copper/carbon tubes were used as the substitute of part of tin and all of lead in the tin bronze matrix, and the tribological properties of carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composites were studied. The effects of the carbon nanotube volume fraction and sliding distance in unlubricated ball-on-disc wear test were investigated. The 3 vol pct carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composite shows the Vickers hardness of 126.9, which is approximately 1.6 times higher than that of Cu-6 wt pct Sn-6 wt pct Zn-3 wt pct Pb tin bronze. The wear rate and average friction coefficients of 3 vol pct carbon nanotube-reinforced Cu-4 wt pct Sn-6 wt pct Zn composite were lower than those of the Cu-6 wt pct Sn-6 wt pct Zn-3 wt pct Pb tin bronze, respectively.

  15. Influence of Coating with Some Natural Based Materials on the Erosion Wear Behavior of Glass Fiber Reinforced Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Aseel Basim Abdul Hussein

    2015-06-01

    Full Text Available In the present study, composites were prepared by Hand lay-up molding. The composites constituents were epoxy resin as a matrix, 6% volume fractions of glass fibers (G.F as reinforcement and 3%, 6% volume fractions of preparation natural material (Rice Husk Ash, Carrot Powder, and Sawdust as filler. Studied the erosion wear behavior and coating by natural wastes (Rice Husk Ash with epoxy resin after erosion. The results showed the non – reinforced epoxy have lower resistance erosion than natural based material composites and the specimen (Epoxy+6%glass fiber+6%RHA has higher resistance erosion than composites reinforced with carrot powder and sawdust at 30cm , angle 60°, grin size of sand 425µm , temperature 30Ċ , 300 gm salt content in 2liter of water and 15 hour. Coating specimen with mixed epoxy resin -RHA with particles size in the range (1.4-4.2 µm improves erosion wear resistance characteristics of the coated specimen, coating thickness was (16 ± 1 μm and after erosion at (15 hour the thickness was (10 μm .

  16. The fractal characterization of wear particles in relation to the wear status

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The topography and distribution of wear particles produced in the wear process containmuch information about the wear status. Fractal geometry is applied in this paper to describe thewear particle accumulation in order to characterize the wear status change. The sliding wear test isperformed on a pin-on-disc apparatus using steel disc and brass pin. The investigation resultsshow that wear particle accumulation presents a strong bi-fractal behavior. Also, the fractal dimen-sion varies in correspondence to the wear status change. A new fractal index characterizing thewear particle accumulation is put forward. The wear tests of brass pin demonstrate that the fractalindex is effective in describing the wear status change.

  17. SLIM for multispectral FRET imaging

    Science.gov (United States)

    Rück, A.; Dolp, F.; Steiner, R.; Steinmetz, C.; von Einem, B.; von Arnim, C. A. F.

    2008-02-01

    Spectral fluorescence lifetime imaging (SLIM) is an advanced imaging technique, which combines spectral with time resolved detection. Real spectral information is achieved by using a grating in front of a PML-array, which allows time-correlated single photon counting (TCSPC). Whereas spectrally resolved fluorescence imaging alone has a reasonable sensitivity, the specificity of fluorescence detection can be improved by considering the fluorescence lifetime. The various possibilities which SLIM offers to improve FRET (resonant energy transfer) will be discussed as well as successfully realized applications. These include FRET measurements for protein interactions, related to Alzheimer's disease. Special attention will be focused on molecules involved in the processing and trafficking of the amyloid precursor protein (APP), as trafficking proteins of the GGA family and β-secretase BACE). Taking into account also the lifetime of the acceptor could enhance reliability of the FRET result.

  18. Friction and wear behavior of TiC particle reinforced ZA43 matrix composites

    Institute of Scientific and Technical Information of China (English)

    谢贤清; 张荻; 刘金水; 吴人洁

    2001-01-01

    TiC/ZA43 composites were fabricated by XDTM and stirring-casting techniques. The tribology properties of the unreinforced ZA43 alloy and the composites were studied by using a block-on-ring apparatus. Experimental results show that the incorporation of TiC particles improves the microstructure of ZA43 matrix alloy. The coefficient of friction μ and the width of worn groove decrease with the increase of TiC volume fraction φ(TiC). The width of worn groove and μ of the composite during wear testing increase with increasing the applied load. Metallographic examinations reveal that unreinforced ZA43 alloy has deep ploughing grooves with obvious adhesion phenomenon, whereas TiC/ZA43 composites have smooth worn surface. Delamination formation is related to the fatigue cracks and the shear cracks on the surface.

  19. Wear Behavior and Its Correlation with Mechanical Properties of TiB2 Reinforced Aluminium-Based Composites

    Directory of Open Access Journals (Sweden)

    N. B. Dhokey

    2011-01-01

    Full Text Available Aluminium-based TiB2 reinforced composite is a promising material to be used as brake drum material, and it may emerge as substitute for conventional gray cast iron. Aluminium-based composites containing 2% by wt copper reinforced with 2.5 and 5 wt% TiB2 composites were made in induction furnace by in situ synthesis process using simultaneous addition of halide fluxes (K2TiF6 and KBF4. These cast composites were evaluated for microstructures, hardness, flow curve properties, and tensile properties. It was observed that overall wear behavior gave reasonably good correlation with mechanical properties of composites as compared to gray cast iron.

  20. Effect of deep cryogenic treatment and tempering on microstructure and mechanical behaviors of a wear-resistant austempered alloyed bainitic ductile iron

    Directory of Open Access Journals (Sweden)

    Chen Liqing

    2015-01-01

    Full Text Available In this paper, the effect of deep cryogenic treatment in combination with conven- tional heat treatment process was investigated on microstructure and mechanical behaviors of alloyed bainitic ductile iron. Three processing schedules were employed to treat this alloyed ductile iron including direct tempering treatment, tempering.+deep cryogenic treatment and deep cryogenic treatment.+tempering treatments. The microstructure and mechanical behavior, especially the wear resistance, have been evaluated after treated by these three schedules. The results show that martensite microstructure can be obviously refined and the precipitation of dispersed carbides is promoted by deep cryogenic treatment at .−196 ∘C for 3 h after tempered at 450 ∘C for 2 h. In this case, the alloyed bainitic ductile iron possesses rather high hardness and wear-resistance than those processed by other two schedules. The main wear mechanism of the austempered alloyed ductile iron with deep cryogenic treatment and tempering is micro-cutting wear in association with plastic deformation wear.

  1. Eutectic modification in a low-chromium white cast iron by a mixture of titanium, rare earths, and bismuth: Part II. effect on the wear behavior

    Science.gov (United States)

    Bedolla-Jacuinde, A.; Aguilar, S. L.; Maldonado, C.

    2005-06-01

    In this work, we studied the wear behavior of a low-Cr white cast iron (WCI) modified with ferrotitanium-rare earths-bismuth (Fe-Ti-RE-Bi) up to 2%. These additions modified the eutectic carbide structure of the alloy from continuous ledeburite into a blocky, less interconnected carbide network. The modified structure was wear tested under pure sliding conditions against a hardened M2 steel counter-face using a load of 250 N. It was observed that wear resistance increased as the modifier admixture increased. The modified structure had smaller more isolated carbides than the WCI with no Fe-Ti-RE-Bi additions. It was observed that large carbides fracture during sliding, which destabilizes the structure and causes degradation in the wear behavior. A transition from abrasive to oxidative wear after 20 km sliding occurred for all alloys. In addition, the modified alloys exhibited higher values of hardness and fracture toughness. These results are discussed in terms of the modified eutectic carbide microstructure.

  2. Wear and corrosion behavior of oxygen implanted biomedical titanium alloy Ti-13Nb-13Zr

    Science.gov (United States)

    Mohan, L.; Anandan, C.

    2013-10-01

    Titanium alloy Ti-13Nb-13Zr was implanted with oxygen ions by plasma immersion ion implantation. The influence of oxygen ion implantation on the growth of apatite on the implanted sample was investigated by immersion in Hanks’ solution and also by potentiodynamic polarization studies in Hanks’ solution. XRD shows the formation of mainly anatase form of oxide. FESEM images of immersion tested samples show that growth of apatite is more with larger sized deposits on oxygen implanted surface as compared to that on the untreated substrate. XPS investigation of corrosion tested and 1 day immersed samples show higher amount of calcium, phosphorous and oxygen in hydroxide/phosphate form on the oxygen implanted sample. EDS results also confirm higher concentration of Ca and P on oxygen implanted sample. Polarization and electrochemical impedance spectroscopy studies show that the oxygen implanted layer behaves like a nearly ideal capacitor with better passivation characteristics. In sliding wear studies, the implanted layers displayed a lower friction coefficient as compared to the substrate one.

  3. Effects of nano-LaF3 on the friction and wear behaviors of PTFE-based bonded solid lubricating coatings under different lubrication conditions

    Science.gov (United States)

    Jia, Yulong; Wan, Hongqi; Chen, Lei; Zhou, Huidi; Chen, Jianmin

    2016-09-01

    Influence of nanometer lanthanum fluoride (nano-LaF3) on the tribological behaviors of polytetrafluoroethylene (PTFE) bonded solid lubricating coatings were investigated using a ring-on-block friction-wear tester under dry friction and RP-3 jet fuel lubrication conditions. The worn surfaces and transfer films formed on the counterpart steel rings were observed by scanning electron microscope (SEM) and optical microscope (OM), respectively. The microstructures of the nano-LaF3 modified coatings and the distribution states of nano-LaF3 were studied by field-emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM), respectively. The results show that incorporation of nano-LaF3 improves the microhardness and the friction-reduced and anti-wear abilities of PTFE bonded solid lubricating coatings. The wear life of the modified coating is about 6 times longer than that of the coating without nano-LaF3 filler at a relatively low applied load (200 N) and rotary speed (1000 rev/min) under dry friction condition. The friction coefficient and wear life of the modified coating decrease with increase of applied load under dry friction, but the friction coefficient has hardly any variation and wear life decreases under RP-3 jet fuel lubrication condition. In addition, the friction coefficient of the modified coating reduces with the rotary speed increasing under dry sliding but has little change under RP-3 lubrication, the wear life increases firstly and then decreases. The results indicated that the wear failure mechanism is dominated by applied load, which plays an important role in guidance of application of nano-LaF3 modified PTFE bonded coating under different working environment.

  4. Effect of amide type modified rapeseed oil as lubricating additive on friction and wear behavior of steel-steel and steel-aluminum alloy systems

    Institute of Scientific and Technical Information of China (English)

    FANG Jian-hua; CHEN Bo-shui; LIU Wei-min; DONG Lin; WANG Jiu

    2004-01-01

    A new type of environmentally friendly lube additive-amide type modified rapeseed oil was synthesized and characterized by infrared spectrum. Its effect on the friction and wear behavior of steel-steel and steel-aluminum alloy systems were investigated with a four-ball machine and an Optimol SRV friction and wear tester respectively.The morphographies of the worn surfaces were analyzed by means of scanning electron microscopy(SEM). The worn surfaces of the 2024Al alloy block were analyzed by means of X-ray photoelectron spectroscopy(XPS). The results show that the modified rapeseed oil as additives can obviously decrease the wear rate and friction coefficient of steel pair and steel-aluminum frictional pair. Its lubrication mechanism is inferred that a high strength complex protection films form on the worn surface of the Al alloy due to the adsorption or tribochemistry reaction of a long chain additive molecule and high reaction activity of N element.

  5. Microstructure and Dry-Sliding Wear Behavior of B4C Ceramic Particulate Reinforced Al 5083 Matrix Composite

    Directory of Open Access Journals (Sweden)

    Qian Zhao

    2016-09-01

    Full Text Available B4C ceramic particulate–reinforced Al 5083 matrix composite with various B4C content was fabricated successfully via hot-press sintering under Argon atmosphere. B4C particles presented relative high wettability, bonding strength and symmetrical distribution in the Al 5083 matrix. The hardness value, friction coefficient and wear resistance of the composite were higher than those of the Al 5083 matrix. The augment of the B4C content resulted in the increase of the friction coefficient and decrease of the wear mass loss, respectively. The 30 wt % B4C/Al 5083 composite exhibited the highest wear resistance. At a low load of 50 N, the dominant wear mechanisms of the B4C/Al 5083 composite were micro-cutting and abrasive wear. At a high load of 200 N, the dominant wear mechanisms were micro-cutting and adhesion wear associated with the formation of the delamination layer which protected the composite from further wear and enhanced the wear resistance under the condition of high load.

  6. Microstructural effects on the wear behavior of a biomedical as-cast Co-27Cr-5Mo-0.25C alloy exposed to pulsed laser melting.

    Science.gov (United States)

    Acevedo-Dávila, J L; López, H F; Cepeda-Rodríguez, F; Rodriguez-Reyes, M; García-Vazquez, F; Hernández-Garcia, H M

    2014-06-01

    In this work, the effect of pulsed laser melting on the exhibited microstructure and properties of a cast Co-27Cr-5Mo-0.25C alloy was investigated. In particular, properties such as surface hardness and wear behavior of the laser modified microstructure were determined as a function of the implemented laser melting parameters. It was found that laser melting promotes significant grain refinement while preventing the precipitation of coarse carbide phases. Apparently, a refined dendritic grain structure develops which is surrounded by a fine carbide distribution in the interdendritic regions. Moreover, the high-temperature face centered cubic (FCC) phase remains untransformed at room temperature. Hardness measurements and wear testing using a Pin-On-Disk tribological machine indicate that the modified laser surfaces exhibit both, high wear resistance and high microhardness when compared with the untreated as-cast Co-27Cr-5Mo-0.25C alloy. In particular, it was found that the laser modified surfaces exhibit improved wear and friction properties comparable to the ones found in Co-Cr-Mo alloys with a predominantly hexagonal closest packed (HCP) matrix. However, surface defects associated with the laser process can be detrimental for the improved wear performance and they should be considered in identifying the proper laser parameters in alloy melting.

  7. Mechanical Properties and Corrosion-Abrasion Wear Behavior of Low-Alloy MnSiCrB Cast Steels Containing Cu

    Science.gov (United States)

    Luo, Kaishuang; Bai, Bingzhe

    2011-01-01

    Two medium carbon low-alloy MnSiCrB cast steels containing different Cu contents (0.01 wt pct and 0.62 wt pct) were designed, and the effect of Cu on the mechanical properties and corrosion-abrasion wear behavior of the cast steels was studied. The results showed that the low-alloy MnSiCrB cast steels obtained excellent hardenability by a cheap alloying scheme. The microstructure of the MnSiCrB cast steels after water quenching from 1123 K (850 °C) consists of lath martensite and retained austenite. After tempering at 503 K (230 °C), carbides precipitated, and the hardness of the cast steels reached 51 to 52 HRC. The addition of Cu was detrimental to the ductility and impact toughness but was beneficial to the wear resistance in a corrosion-abrasion wear test. The MnSiCrB cast steel with Cu by the simple alloying scheme and heat treatment has the advantages of being high performance, low cost, and environmentally friendly. It is a potential, advanced wear-resistant cast steel for corrosion-abrasion wear conditions.

  8. Fretting fatigue in AISI 1015 steel

    Indian Academy of Sciences (India)

    R Gnanamoorthy; R Rosi Reddy

    2002-04-01

    A small osillatory movement between two contacting surfaces is termed as fretting and on many occasions it acts as the crack initiation site leading to catastrophic failure of the overall structure. The occurrence of fretting is observed in many engineering structures such as shaft flanges, gas turbines, steel ropes etc. An experimental facility, which can simulate the fretting fatigue in many engineering applications, is the primary requirement of the research program. A laboratory fretting fatigue test facility capable of varying many influencing parameters of fretting fatigue such as slip amplitutde, frequency, contact pressure, etc is designed and developed. Preliminary investigations on plain and fretting fatigue behaviour of AISI 1015 structural steel are reported in this paper. A strength reduction factor of about 1.30 was obtained due to fretting for the test material under the present experimental conditions. Influence of contact load on fretting was also studied. Increasing fretting contact load decreased the fatigue life in the range investigated. Failure analysis showed typical stage I oblique crack growth followed by stage II straight crack perpedicular to the fretting zone.

  9. Comprehensive study of the abrasive wear and slurry erosion behavior of an expanded system of high chromium cast iron and microstructural modification for enhanced wear resistance

    Science.gov (United States)

    Chung, Reinaldo Javier

    High chromium cast irons (HCCIs) have been demonstrated to be an effective material for a wide range of applications in aggressive environments, where resistances to abrasion, erosion and erosion-corrosion are required. For instance, machinery and facilities used in mining and extraction in Alberta's oil sands suffer from erosion and erosion-corrosion caused by silica-containing slurries, which create challenges for the reliability and maintenance of slurry pumping systems as well as other processing and handling equipment. Considerable efforts have been made to determine and understand the relationship between microstructural features of the HCCIs and their wear performance, in order to guide the material selection and development for specific service conditions with optimal performance. The focus was previously put on a narrow group of compositions dictated by ASTM A532. However, with recent advances in casting technology, the HCCI compositional range can be significantly expanded, which potentially brings new alloys that can be superior to those which are currently employed. This work consists of three main aspects of study. The first one is the investigation of an expanded system of white irons with their composition ranging from 1 to 6 wt.% C and 5 to 45 wt.% Cr, covering 53 alloys. This work has generated wear and corrosion maps and established correlation between the performance and microstructural features for the alloys. The work was conducted in collaboration with the Materials Development Center of Weir Minerals in Australia, and the results have been collected in a database that is used by the company to guide materials selection for slurry pump components in Alberta oil sands and in other mining operations throughout the world. The second part consists of three case studies on effects of high chromium and high carbon, respectively, on the performance of the HCCIs. The third aspect is the development of an approach to enhance the wear resistance of

  10. A Possible Link Between Macroscopic Wear and Temperature Dependent Friction Behaviors of MoS2 Coatings

    Science.gov (United States)

    2008-09-01

    P., Rabinowicz , E., Iwasa, Y.: Friction and wear of polymeric materials at 293-k, 77-k and 4.2-k. Cryogenics 31, 695–704 (1991). doi:10.1016/0011-2275...Lett. 27, 113–117 (2007) 9. Michael, P.C., Rabinowicz , E., Iwasa, Y.: Thermal activation in boundary lubricated friction. Wear 193, 218–225 (1996

  11. Effect of Produced Fluid on the Wear Behavior of Grade D Sucker Rod and N80 Type Tubing

    Institute of Scientific and Technical Information of China (English)

    YanTingjun; WangKuisheng

    2005-01-01

    Inuestigated wear tests of grade D sucker rod and N80 tubing with a produced liquid are the effect of the water cut of produced,liquid on the wear rate and the wear coefficient of the friction pair. And presented here is a comparison of tribological performance of tubing/sucker rod with sprayed tubing/sucker rod and tubing/sprayed sucker rod. The results show that one of the main reasons for wear failure between the sucker rod and the tubing is a high water cut of the produced liquid. The wear rate increases greatly when the water cut ranges from 70% to 85%, and increases gradually when the water cut is less than 70% or more than 85%. The higher the water cut is, the greater the wear rate will be. SEM (scanning electron microscope) micrographs show that the worn surface of the tubing is smoother, with shallow grooves, when the water cut is 55%; when the water cut is 95%, there are broader and deeper grooves on the worn surface. The results also show that the wear rate of the sprayed wear-resistant coating of sucker rod/tubing is less than that of the unsprayed sucker rod/tubing.

  12. Verification of the coupled fluid/solid transfer in a CASL grid-to-rod-fretting simulation : a technical brief on the analysis of convergence behavior and demonstration of software tools for verification.

    Energy Technology Data Exchange (ETDEWEB)

    Copps, Kevin D.

    2011-12-01

    For a CASL grid-to-rod fretting problem, Sandia's Percept software was used in conjunction with the Sierra Mechanics suite to analyze the convergence behavior of the data transfer from a fluid simulation to a solid mechanics simulation. An analytic function, with properties relatively close to numerically computed fluid approximations, was chosen to represent the pressure solution in the fluid domain. The analytic pressure was interpolated on a sequence of grids on the fluid domain, and transferred onto a separate sequence of grids in the solid domain. The error in the resulting pressure in the solid domain was measured with respect to the analytic pressure. The error in pressure approached zero as both the fluid and solids meshes were refined. The convergence of the transfer algorithm was limited by whether the source grid resolution was the same or finer than the target grid resolution. In addition, using a feature coverage analysis, we found gaps in the solid mechanics code verification test suite directly relevant to the prototype CASL GTRF simulations.

  13. Friction and wear behaviors of dental zirconia ceramics%牙科氧化锆瓷摩擦磨损性能的研究

    Institute of Scientific and Technical Information of China (English)

    宋海燕; 曾剑玉; 司文捷

    2014-01-01

    目的:研究牙科氧化锆瓷的摩擦磨损性能以及与天然牙釉质摩擦磨损性能匹配情况。方法微摩擦磨损试验机上,以滑石瓷为对磨物,人工唾液润滑下对Upcera ST 和 Zenostar Zr Translucent氧化锆瓷、牙釉质和饰面瓷进行摩擦磨损实验。实验前,用激光共聚焦显微镜测试件表面粗糙度Ra;实验结束后,光学显微镜下观察滑石瓷磨斑形貌、测量滑石瓷磨斑面积;激光共聚焦显微镜测量试件磨斑宽度;扫描电镜下观察试件磨斑的微观形貌。采用单因素方差分析进行统计学分析。结果饰面瓷的磨斑宽度大于其它3种材料(P<0.01),饰面瓷对磨物滑石瓷磨斑面积大于氧化锆瓷和牙釉质(P<0.05)。结论与饰面瓷对比,氧化锆瓷具有更佳耐磨性及较低对磨物磨损,并且与天然牙釉质的磨擦学性能相似。%Objective To evaluate the zirconia ceramics ’ friction and wear behaviors to compare with natural enamel. Methods In a micro friction and wear testing apparatus, the friction and wear tests on Upcera ST,Zenostar Zr Translucent,teeth enamel and veneering ceramic were carried out under artificial saliva lubrication condition and steatite served as antagonist. Before wear test, surface roughness ( Ra) was determined by laser scanning confocal microscope. After test , the wear morphology of steatite was observed under light microscope and the wear area measured. The width of the wear area was measured by laser scanning confocal microscope and the scanning electron microscopy was used to observe the wear surface micro-morphology of the ceramics and enamel. Statistical analysis was performed using one-way analysis of variance (ANOVA). Results The width of the wear area on the veneering ceramic was greater than other three materials(P <0. 01). Veneering ceramic caused significantly higher antagonist wear than zirconia and teeth enamel ( P< 0. 05 ) . Conclusion Zirconia ceramics yielded

  14. A Study on Surface Modification of Al7075-T6 Alloy against Fretting Fatigue Phenomenon

    Directory of Open Access Journals (Sweden)

    E. Mohseni

    2014-01-01

    Full Text Available Aircraft engines, fuselage, automobile parts, and energy saving strategies in general have promoted the interest and research in the field of lightweight materials, typically on alloys based on aluminum. Aluminum alloy itself does not have suitable wear resistance; therefore, it is necessary to enhance surface properties for practical applications, particularly when aluminum is in contact with other parts. Fretting fatigue phenomenon occurs when two surfaces are in contact with each other and one or both parts are subjected to cyclic load. Fretting drastically decreases the fatigue life of materials. Therefore, investigating the fretting fatigue life of materials is an important subject. Applying surface modification methods is anticipated to be a supreme solution to gradually decreasing fretting damage. In this paper, the authors would like to review methods employed so far to diminish the effect of fretting on the fatigue life of Al7075-T6 alloy. The methods include deep rolling, shot peening, laser shock peening, and thin film hard coatings. The surface coatings techniques are comprising physical vapor deposition (PVD, hard anodizing, ion-beam-enhanced deposition (IBED, and nitriding.

  15. Wear behavior of the surface alloyed AISI 1020 steel with Fe-Nb-B by TIG welding technique

    Energy Technology Data Exchange (ETDEWEB)

    Kilinc, B., E-mail: bkilinc@sakarya.edu.tr; Durmaz, M.; Abakay, E. [Department of Metallurgical and Materials Engineering, Institute of Arts and Sciences, SakaryaUniversity, Esentepe Campus, 54187Sakarya (Turkey); Sen, U.; Sen, S. [Department of Metallurgical and Materials Engineering, Engineering Faculty, Sakarya University, Esentepe Campus, 54187 Sakarya (Turkey)

    2015-03-30

    Weld overlay coatings also known as hardfacing is a method which involves melting of the alloys and solidification for applied coatings. Recently hardfacing by welding has become a commonly used technique for improvement of material performance in extreme (high temperature, impact/abrasion, erosion, etc.) conditions.In the present study, the coatings were produced from a mixture of ferrous niobium, ferrous boron and iron powders in the ranges of -45µm particle size with different ratio. Fe{sub 12}Nb{sub 5}B{sub 3} and Fe{sub 2}NbBalloys were coated on the AISI 1020 steel surface by TIG welding. The phases formed in the coated layer are Fe{sub 2}B, NbB{sub 2}, NbFeB and Fe0,2 Nb{sub 0,8} phases. The hardness of the presence phases are changing between 1689±85 HV{sub 0.01}, and 181±7 HV{sub 0.1}. Microstructural examinations were realized by optical and scanning electron microscopy. The wear and friction behaviors of Fe{sub 12}Nb{sub 5}B{sub 3} and Fe2NbB realized on the AISI 1020 steel were investigated by the technique of TIG welding by using ball-on-disk arrangement against alumina ball.

  16. Fluorescence Resonance Energy Transfer (FRET) sensor

    CERN Document Server

    Hussain, Syed Arshad; Chakraborty, Sekhar; Saha, Jaba; Roy, Arpan Datta; Chakraborty, Santanu; Debnath, Pintu; Bhattacharjee, D

    2014-01-01

    The applications of Fluorescence resonance energy transfer (FRET) have expanded tremendously in the last 25 years, and the technique has become a staple technique in many biological and biophysical fields. FRET can be used as spectroscopic ruler in various areas such as structural elucidation of biological molecules and their interactions, in vitro assays, in vivo monitoring in cellular research, nucleic acid analysis, signal transduction, light harvesting, and metallic nanomaterials etc. Based on the mechanism of FRET a variety of novel chemical sensors and Biosensors have been developed. This review highlights the recent applications of sensitive and selective ratiometric FRET based sensors.

  17. Wear resistance properties of austempered ductile iron

    Science.gov (United States)

    Lerner, Y. S.; Kingsbury, G. R.

    1998-02-01

    A detailed review of wear resistance properties of austempered ductile iron (ADI) was undertaken to examine the potential applications of this material for wear parts, as an alternative to steels, alloyed and white irons, bronzes, and other competitive materials. Two modes of wear were studied: adhesive (frictional) dry sliding and abrasive wear. In the rotating dry sliding tests, wear behavior of the base material (a stationary block) was considered in relationship to countersurface (steel shaft) wear. In this wear mode, the wear rate of ADI was only one-fourth that of pearlitic ductile iron (DI) grade 100-70-03; the wear rates of aluminum bronze and leaded-tin bronze, respectively, were 3.7 and 3.3 times greater than that of ADI. Only quenched DI with a fully martensitic matrix slightly outperformed ADI. No significant difference was observed in the wear of steel shafts running against ADI and quenched DI. The excellent wear performance of ADI and its countersurface, combined with their relatively low friction coefficient, indicate potential for dry sliding wear applications. In the abrasive wear mode, the wear rate of ADI was comparable to that of alloyed hardened AISI 4340 steel, and approximately one-half that of hardened medium-carbon AISI 1050 steel and of white and alloyed cast irons. The excellent wear resistance of ADI may be attributed to the strain-affected transformation of high-carbon austenite to martensite that takes place in the surface layer during the wear tests.

  18. Correlation between Wear Resistance and Lifetime of Electrical Contacts

    Directory of Open Access Journals (Sweden)

    Jian Song

    2012-01-01

    Full Text Available Electrical contacts are usually plated in order to prevent corrosion. Platings of detachable electrical contacts experience wear because of the motion between contacts. Once the protecting platings have been worn out, electrical contacts will fail rapidly due to corrosion or fretting corrosion. Therefore the wear resistance of the platings is a very important parameter for the long lifetime of electrical contacts. Many measures which improve the wear resistance can diminish the conductivity of the platings. Due to the fact that platings of electrical contacts must have both a high wear resistance and a high electrical conductivity, the manufacturing of high performance platings of electrical contacts poses a great challenge. Our study shows firstly the correlation between the wear resistance of platings and lifetime of electrical contacts and then the measures, which improve the wear resistance without impairing the electrical performance of the contacts.

  19. HEAT TREATING OF SINTERED Fe-1.5Mo-0.7C STEELS AND THEIR SLIDING WEAR BEHAVIOR

    Institute of Scientific and Technical Information of China (English)

    J.A. Wang; Y. He; H. Danninger

    2003-01-01

    The influence of heat treating on mechanical properties as well as on the sliding wearbehavior of sintered Fe-1.SMo-0.7C steels was experimentally studied. The microstruc-tures of sintered steels change from upper bainite to martensite, tempered martensite,pearlite and lower bainite depending on the heat treating conditions. Heat treatingincreases the hardness of sintered steels but high tempering temperature, i.e. 700℃,causes the hardness to be even lower than that of the as-sintered ones. The impactenergy of sintered steels increases with increasing tempering temperature and arrivesthe highest at 700℃, while the steels tempered at 200℃ have the highest transverserupture strength. Austempering results in fair good overall properties, such as hard-ness, impact energy, and transverse rupture strength. When the sintered steels wereaustempered, oil-quenched or tempered below 400℃ after quenched, the wear coef-ficient becomes considerably lower. Fair high hardness, such as HV30 > 380, andstructures of martensite, tempered martensite or lower bainite are beneficial to low-ering the wear coefficient. Under the wear test conditions given, delamination andoxidational wear are the main wear regimes for sintered Fe-1.5Mo-0.7C steels. Fe3O4in the wear debris is beneficial to lowering wear coefficient.

  20. Creep behavior and wear resistance of Al 5083 based hybrid composites reinforced with carbon nanotubes (CNTs) and boron carbide (B{sub 4}C)

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, Ali [Faculty of Materials & Manufacturing Processes, Malek-e-Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Abdollahi, Alireza, E-mail: alirezaabdollahi1366@gmail.com [Faculty of Materials & Manufacturing Processes, Malek-e-Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Biukani, Hootan [Faculty of Engineering, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

    2015-11-25

    In the current research, aluminum based hybrid composite reinforced with boron carbide (B{sub 4}C) and carbon nanotubes (CNTs) was produced by powder metallurgy method. creep behavior, wear resistance, surface roughness, and hardness of the samples were investigated. To prepare the samples, Al 5083 powder was milled with boron carbide particles and carbon nanotubes using planetary ball mill under argon atmosphere with ball-to-powder weight ratio of 10:1 for 5 h. Afterwards, the milled powders were formed by hot press process at 380{sup °}C and then were sintered at 585{sup °}C under argon atmosphere for 2 h. There was shown to be an increase in hardness values of composite with an increase in B{sub 4}C content. The micrograph of worn surfaces indicate a delamination mechanism due to the presence of CNTs and abrasion mechanism in composite containing 10 vol.%B{sub 4}C. Moreover, it was shown that increasing B{sub 4}C content increases the wear resistance by 3 times under a load of 20 N and 10 times under a load of 10 N compared to CNTs-reinforced composite. surface roughness of the composite containing 5 vol.%CNT has shown to be more than other samples. The results of creep test showed that adding carbon nanotubes increases creep rate of Al 5083 alloy; however, adding B{sub 4}C decreases its creep rate. - Highlights: • Al 5083/(CNTs + B{sub 4}C) hybrid composite was produced by powder metallurgy method. • Creep behavior, wear resistance, surface roughness, and Hardness of samples were investigated. • Addition of CNTs to Al 5083 matrix reduces alloy hardness, wear resistance and creep strength. • By addition of B{sub 4}C and composite hybridization, creep strength and wear resistance increased. • Surface roughness of Al-5 vol.%CNT has shown to be more than other samples.

  1. Wear Behavior of Aluminum Alloy 6061-Based Composites Reinforced with SiC, Al2O3, and Red Mud: A Comparative Study

    Science.gov (United States)

    Singla, Yogesh Kumar; Chhibber, Rahul; Bansal, Hitesh; Kalra, Anil

    2015-09-01

    Metal-matrix composites are widely used in shipping, aerospace, automotive, and nuclear applications. Research attempts have been made in the past to reduce the cost of processing of composites, decrease the weight of the composites, and increase the desired performance characteristics. In this research article, an attempt has been made in using red mud obtained as an industrial waste during the production of aluminum from bauxite ore. This article discusses the novel findings of the experimental study on the dry sliding wear behavior of aluminum alloy 6061-based composites reinforced individually with red mud, SiC, and Al2O3. The microstructural characterization of the composites provides the further insight into the structure—wear behavior of the processed composites.

  2. Influence of surface coating on Ti811 alloy resistance to fretting fatigue at elevated temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaohua; LIU Daoxin

    2009-01-01

    An extensive study of the composition distribution, bonding strength, hardness, and wear resistance of a 0Cr18Ni9 film deposited on a Ti811 titanium alloy surface by ion beam enhanced deposition (IBED) is presented. Shot peening was introduced to post-treat the modified surface to synergistically improve the fretting fatigue resistance of the Ti811 alloy at 350~C. The results indicate that the 0Cr18Ni9 film with high density, small grain size, low void radio, and high bonding strength can be prepared using IBED. As a result, the hardness, wear resistance, and fretting fatigue resistance of the Ti811 alloy are increased to a remarkable extent. Compared with shot peening treatment or IBED 0Cr18Ni9 film alone, the Ti811 titanium alloy with an IBED 0Cr18Ni9 film combined with shot peening shows a higher fretting fatigue resistance at 350℃. This is due to the synergistic effect of the high wear resistance of the film surface and the residual compressive stress induced by shot peening.

  3. Eye Wear

    Science.gov (United States)

    Eye wear protects or corrects your vision. Examples are Sunglasses Safety goggles Glasses (also called eyeglasses) Contact ... jobs and some sports carry a risk of eye injury. Thousands of children and adults get eye ...

  4. Effects of nano-LaF{sub 3} on the friction and wear behaviors of PTFE-based bonded solid lubricating coatings under different lubrication conditions

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Yulong [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wan, Hongqi, E-mail: wanhq@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Chen, Lei, E-mail: chenlei@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Zhou, Huidi [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Chen, Jianmin, E-mail: chenjm@lzb.ac.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

    2016-09-30

    Highlights: • Nano-LaF{sub 3} was used to modify tribological behavior of PTFE bonded solid lubricating coating. • The tribological properties of lubricating coatings were investigated under different lubrication conditions. • The modified PTFE bonded coating exhibited superior tribological performance both under two kinds of lubrication conditions. - Abstract: Influence of nanometer lanthanum fluoride (nano-LaF{sub 3}) on the tribological behaviors of polytetrafluoroethylene (PTFE) bonded solid lubricating coatings were investigated using a ring-on-block friction-wear tester under dry friction and RP-3 jet fuel lubrication conditions. The worn surfaces and transfer films formed on the counterpart steel rings were observed by scanning electron microscope (SEM) and optical microscope (OM), respectively. The microstructures of the nano-LaF{sub 3} modified coatings and the distribution states of nano-LaF{sub 3} were studied by field-emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM), respectively. The results show that incorporation of nano-LaF{sub 3} improves the microhardness and the friction-reduced and anti-wear abilities of PTFE bonded solid lubricating coatings. The wear life of the modified coating is about 6 times longer than that of the coating without nano-LaF{sub 3} filler at a relatively low applied load (200 N) and rotary speed (1000 rev/min) under dry friction condition. The friction coefficient and wear life of the modified coating decrease with increase of applied load under dry friction, but the friction coefficient has hardly any variation and wear life decreases under RP-3 jet fuel lubrication condition. In addition, the friction coefficient of the modified coating reduces with the rotary speed increasing under dry sliding but has little change under RP-3 lubrication, the wear life increases firstly and then decreases. The results indicated that the wear failure mechanism is dominated by applied load

  5. Quantifying Cutting and Wearing Behaviors of TiN- and CrN-Coated AISI 1070 Steel

    Science.gov (United States)

    Cakan, Ahmet; Ozkaner, Vedat; Yildirim, Mustafa M.

    2008-01-01

    Hard coatings such as titanium nitride (TiN) and chromium nitride (CrN) are widely used in cutting and forming tools against wear and corrosion. In the present study, hard coating films were deposited onto AISI 1070 steels by a cathodic arc evaporation plating (CAVP) technique. These samples were subjected to wear in a conventional lathe for investigating the tribological behaviour of coating structure, and prenitrided subsurface composition was characterized using scanning electron microscopy (SEM), line scan analyses and X-ray diffraction (XRD). The wear properties of TiN- and CrN-coated samples were determined using an on-line monitoring system. The results show that TiN-coated samples demonstrate higher wear resistance than CrN-coated samples. PMID:27873912

  6. Dry Sliding Wear Behavior of Spark Plasma Sintered Fe-Based Bulk Metallic Glass/Graphite Composites

    Directory of Open Access Journals (Sweden)

    Xiulin Ji

    2016-09-01

    Full Text Available Bulk metallic glass (BMG and BMG-graphite composites were fabricated using spark plasma sintering at the sintering temperature of 575 °C and holding time of 15 min. The sintered composites exhibited partial crystallization and the presence of distributed porosity and graphite particles. The effect of graphite reinforcement on the tribological properties of the BMG/graphite composites was investigated using dry ball-on-disc sliding wear tests. The reinforcement of graphite resulted in a reduction in both the wear rate and the coefficient of friction as compared to monolithic BMG samples. The wear surfaces of BMG/graphite composites showed regions of localized wear loss due to microcracking and fracture, as was also the case with the regions covered with graphite-rich protective film due to smearing of pulled off graphite particles.

  7. Microstructures and friction-wear behaviors of cathodic arc ion plated CrC coating at high temperatures

    Science.gov (United States)

    Dejun, Kong; Shouyu, Zhu

    2016-11-01

    A CrC coating was deposited on YT14 cemented carbide cutting tools by a CAIP (cathodic arc ion plating). The surface and interface morphologies, chemical composition, and phases of the obtained coating were analyzed with a field emission scanning electronic microscope (FESEM), energy dispersive spectroscope (EDS), and x-ray diffraction (XRD), respectively. The COFs (coefficient of frictions) and worn morphologies of the CrC coating at 300 °C, 400 °C, and 500 °C were investigated by using a high temperature tribometer, the effects of wear temperatures on the friction-wear properties of the CrC coating were discussed. The results show that the CrC coating exhibits fine dense structure, and the lattice constants of CrC coatings are dependent on processing parameters. The C and Cr elements in the coating are mutually diffused with the W, Co, and Ti in the substrate. The average COF of the coating at 300 °C, 400 °C, and 500 °C is 0.64, 0.63, and 0.40, respectively. The Cr2O3 layer formed on the CrC coating at 500 °C has excellent oxidation resistance, which improves lubrication and wear performance, the wear mechanism is abrasive wear and oxidation wear.

  8. Effect of TiB2 Additives on Wear Behavior of NiCrBSi-Based Plasma-Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Oleksandr UMANSKYI

    2016-05-01

    Full Text Available The influence of titanium diboride additives on microstructure and wear-resistance of NiCrBSi thermally sprayed coatings deposited on a steel substrate has been studied. NiCrBSi-based composite powders with 10, 20, 40 wt.% TiB2 particles content were produced. The structure of NiCrSiB-TiB2 coatings consists of TiB2 and CrB grains distributed in Ni-based matrix. The wear-resistance of NiCrSiB-TiB2 plasma sprayed coatings in dry sliding conditions against the same coating using pin-on-disk tester. It was determined that the amount of titanium diboride particles in  NiCrBSi-based coatings influences essentially on the wear  resistance and wear mechanism. The NiCrBSi-based plasma sprayed coatings containing 20 wt. % of TiB2 possess the highest wear resistance due to the realization of mechano-oxidational wear mechanism.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7307

  9. Tribology of Si/SiO2 in humid air: transition from severe chemical wear to wearless behavior at nanoscale.

    Science.gov (United States)

    Chen, Lei; He, Hongtu; Wang, Xiaodong; Kim, Seong H; Qian, Linmao

    2015-01-13

    Wear at sliding interfaces of silicon is a main cause for material loss in nanomanufacturing and device failure in microelectromechanical system (MEMS) applications. However, a comprehensive understanding of the nanoscale wear mechanisms of silicon in ambient conditions is still lacking. Here, we report the chemical wear of single crystalline silicon, a material used for micro/nanoscale devices, in humid air under the contact pressure lower than the material hardness. A transmission electron microscopy (TEM) analysis of the wear track confirmed that the wear of silicon in humid conditions originates from surface reactions without significant subsurface damages such as plastic deformation or fracture. When rubbed with a SiO2 ball, the single crystalline silicon surface exhibited transitions from severe wear in intermediate humidity to nearly wearless states at two opposite extremes: (a) low humidity and high sliding speed conditions and (b) high humidity and low speed conditions. These transitions suggested that at the sliding interfaces of Si/SiO2 at least two different tribochemical reactions play important roles. One would be the formation of a strong "hydrogen bonding bridge" between hydroxyl groups of two sliding interfaces and the other the removal of hydroxyl groups from the SiO2 surface. The experimental data indicated that the dominance of each reaction varies with the ambient humidity and sliding speed.

  10. The effect of boron on the wear behavior of iron-based hardfacing alloys for nuclear power plants valves

    Science.gov (United States)

    Yoo, Jeong Wan; Lee, Seong Hun; Yoon, Chong S.; Kim, Seon Jin

    2006-06-01

    The effect of boron of Fe-Cr-C-Si alloys, replacing Stellite 6 traditionally used in nuclear power industry, on the high temperature wear resistance was characterized. Sliding wear tests of Fe-Cr-C-Si-xB (x = 0.3, 0.6, 1.0 and 2.0 wt%) alloys were performed in air at temperatures ranging from 300 to 725 K under a contact stress of 103 MPa. Low-boron alloys containing less than 0.6 wt% boron showed the excellent wear resistance than any other tested alloys in an elevated temperature. The improvement was associated with the matrix hardening by promotion of the γ → α‧ strain-induced martensitic transformation occurred during wear. In addition, protective oxide layers formed on the contacting surface reduced the wear loss by minimizing the direct metal-to-metal contact. However, high-boron alloys containing more than 1 wt% boron showed somewhat larger amount of wear loss than low-boron alloys due to the absence of the strain-induced martensitic transformation and the presence of the brittle FeB particles connected with easy crack initiation.

  11. Wear behavior of contacting between thin film coating on SKD11 ball and 304 stainless steel disk

    Directory of Open Access Journals (Sweden)

    Sriprasird, J.

    2007-11-01

    Full Text Available Wear is a well known problem in metal stamping die, especially on the die working with stainless steel workpiece, in which wear rate is severe. This research considered various types of material coating on tool surface which were regularly practised in modern stamping industry due to the ability to increase wear resistance. The model study of friction "Ball-on-disk" technique was employed throughout this work. The disk was made from stainless steel austenitic grade (SUS304. The ball was made from cold work tool steel, SKD11 (JIS and was hardened to 60±2 HRC. Ball surface conditions selected for this work were non-coated, coated by TiC-CVD, TiCN (TiC/TiCN/TiN Multilayer-CVD and TiCN (TiN/TiCN Double layer-PVD, and treated by VC-TD. Tests were carried out without lubricant. The results show that the coating film and the surface treatment has no effect on the friction coefficient but it can reduce wear rate by 64.1-99.7% at contact pressure condition less than 1,100 MPa. At the higher level of contact pressure, only 2 types of coating, TiCN (Multilayer-CVD and TiC-CVD, can reduce wear rate. The other two, which are TiCN (Double layer-PVD coating film and a surface treatment by VC-TD process, on the contrary increase the rate of wear significantly. This is due to delamination of coating film at high contact pressure. The coating particles of high hardness accelerate wear phenomenon on the tool surface. Therefore, proper selection of tool surface condition depends on level of contact pressure generated in the process.

  12. Refractive behavior changes with six months daily wear of high and low oxygen permeability hydrogel contact lenses

    Directory of Open Access Journals (Sweden)

    W.D.H. Gillan

    2006-01-01

    Full Text Available Introduction: The investigation of myopia and soft contact lenses is not new. Many reports show  that  the  wearing  of  silicone  hydrogel lenses as opposed to conventional disposable hydrogel lenses results in little progression of myopia in the eyes wearing silicone hydrogels. Method: Six subjects wore a silicone hydro-gel lens on one eye while the other eye wore a habitual disposable hydrogel lens for six months of daily wear. Fifty measurements of refractive state in each eye were taken prior to the subjects wearing a silicone lens in one eye and a conven-tional hydrogel lens in the other eye. After six months of daily wear another fifty measurements of refractive state were taken for each subject. Results:  Although  there  is  no  statisti-cal  support  for  the  findings  of  this  study, comet stereo-pairs are used to show the chang-es in refractive state for each subject. Four of  the  six  subjects  showed  an  increase  in myopia in the eye wearing the silicone lens. Discussion:  The  increase  in  myopia in eyes wearing a silicone hydrogel lens is contrary  to  the  findings  of  other  studies.

  13. Wear and Corrosion Behavior of Zr-Doped DLC on Ti-13Zr-13Nb Biomedical Alloy

    Science.gov (United States)

    Kumar, Prateek; Babu, P. Dilli; Mohan, L.; Anandan, C.; Grips, V. K. William

    2013-01-01

    Zirconium (Zr)-doped DLC was deposited on biomedical titanium alloy Ti-13Nb-13Zr by a combination of plasma-enhanced chemical vapor deposition and magnetron sputtering. The concentration of Zr in the films was varied by changing the parameters of the bi-polar pulsed power supply and the Ar/CH4 gas composition. The coatings were characterized for composition, morphology, nanohardness, corrosion resistance in simulated body fluid (SBF) and tribological properties. X-ray photoelectron spectroscopy (XPS) studies on the samples were used to estimate the concentration of Zr in the films. XPS and micro-Raman studies were used to find the variation of I D/ I G ratio with Zr concentration. These studies show that the disorder in the film increased with increasing Zr concentration as deduced from the I D/ I G ratio. Nanohardness measurements showed no clear dependence of hardness and Young's modulus on Zr concentration. Reciprocating wear studies showed a low coefficient of friction (0.04) at 1 N load and it increased toward 0.4 at higher loads. The wear volume was lower at all loads on the coated samples. The wear mechanism changed from abrasive wear on the substrate to adhesive wear after coating. The corrosion current in SBF was unaffected by the coating and corrosion potential moved toward nobler (more positive) values.

  14. Microstructure, Properties and Wear Behaviors of (Ni3Al)p Reinforced Cu Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    I brahim Celikyurek; Nese O. Korpe; Tugba Olcer; Remzi Gurler

    2011-01-01

    Pure copper and its composites reinforced with Ni3Al particles were produced by powder metallurgy (PM). Ni3Al powders were produced by mechanical ball milling from vacuum arc melted compounds. The Ni3Al powders were characterized by X-ray diffraction (XRD). The microscopy examinations revealed that the Ni3Al particles were distributed uniformly in the matrix. The effects of the particle fraction on the density, electrical conductivity, strength and dry sliding wear resistance of composite were investigated. It was found that the density and electrical conductivity of the composites decrease while the compression yield strength and wear resistance of composites increase with an increase in the particle fraction. The dry sliding wear tests were performed with pin-on-disk geometry. After sliding wear tests, the worn surfaces were examined by scanning electron microscopy (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Results have shown that the wear mechanism is oxidative and adhesive.

  15. Wear Behavior of Al-Mg2Si Cast In-situ Composite: Effect of Mg2Si Different Volume Fractions

    Science.gov (United States)

    Ghiasinejad, J.; Emamy, M.; Ghorbani, M. R.; Malekan, A.

    2010-06-01

    Al-Mg2Si in situ composites are great candidates for automobile brake discs due to their low density, reasonably high young's modulus and low thermal expansion coefficient. Thus, understanding wear properties of this composite is of a great importance. In this study wear behavior of an in-situ Al-Mg2Si composite, prepared from a simple casting route, has been investigated using a pin-on-disc configuration concerning the effect of Mg2Si volume fractions, 15, 20 and 25% respectively. It was found that the weight loss increases with increase in reinforce volume fraction which can be due to a coarse morphology of primary Mg2Si particles. It was found that the variations of weight loss with sliding distance comprise different regimes of which the mechanisms are discussed.

  16. Modeling and evaluation of the influence of micro-EDM sparking state settings on the tool electrode wear behavior

    DEFF Research Database (Denmark)

    Puthumana, Govindan

    2017-01-01

    Micromachining technologies are now being employed in various industries for generation of precise features on engineering components. Among these processes, micro electrical discharge machining is a 'non-contact' machining technology suitable for material removal from electrically conductive...... materials characterized by considerable wear ofthe tool used for material removal. This paper presents an investigation involving modeling and estimation of the effect of settings for generation of discharges in stable conditions of micro-EDM on the phenomenon of tool electrode wear. A stable sparking...... condition during the process is achieved with varying voltage (V), capacitance (C), threshold (T), and discharge frequency (f). The tool electrode wear model has revealed that the energy of the sparks interacting with the tool surfaces control the phenomenon through the settings of capacitance followed...

  17. Preparation and wear behavior of polymer matrix composites with an interpenetrating network structure derived from natural sponge

    Energy Technology Data Exchange (ETDEWEB)

    Wang Tianchi; Zhou Tianle; Xiong Dangsheng, E-mail: tianchiwang@yahoo.com.c [Department of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

    2010-03-15

    Natural sponge was used as a template to produce carbon/epoxy resin and (carbon+silicon carbide)/epoxy resin composites with interpenetrating network structures. Carbon with a network structure was first obtained by pyrolysis of the natural sponge. The composites were then obtained by injecting epoxy resin and silicone resin into the carbon. Their microstructures and wear properties were analyzed. The results show that the natural structure of sponge controlled the interpenetrating network structures of the composites. The netlike carbon in the composites reduced the wear rate of the epoxy resin. Compared with the carbon/epoxy resin composite, the (carbon+silicon carbide)/epoxy resin composite shows better wear resistance.

  18. Effect of PostNitride Annealing on Wear and Corrosion Behavior of Titanium Alloy Ti-6Al-4V

    Science.gov (United States)

    Anandan, C.; Mohan, L.

    2016-10-01

    Titanium alloy, Ti-6Al-4V, was plasma nitrided using RF plasma with 100% N at 800 °C and annealed at 850 °C in vacuum. XRD and XPS studies show the formation of titanium nitrides after nitriding and redistribution of nitrogen after annealing. Potentiodynamic polarization and electrochemical impedance spectroscopy studies in Hank's solution show that nitriding decreases the corrosion resistance of the substrate and postnitride annealing improves the corrosion resistance of the nitrided samples. After nitriding, wear rate has decreased by an order of magnitude in reciprocating wear experiments and decreased further in annealed samples in comparison with that of substrate. Thus, postnitride annealing improves both corrosion and wear resistance of the nitrided sample. These improvements are attributed to redistribution of nitrogen and formation of a thin oxide layer on the sample due to annealing.

  19. Wear and Friction Behavior of Stir Cast Al-TiB2 Metal Matrix Composites with Various Lubricants

    Directory of Open Access Journals (Sweden)

    S. Poria

    2016-12-01

    Full Text Available Al- TiB2 metal matrix composites are fabricated using stir cast method and its tribological characterization is done using three different lubricants. Tribological studies are performed in a multi-tribotester using block-on-roller configuration under 25-75 N loads and 400-600 rpm rotational speeds. Four different weight percentages of TiB2 are considered in this study. Comparison between dry condition and lubricated conditions is gleaned to differentiate wear and friction characteristics and SEM images are taken to fortify them. Lubricated conditions yield large reduction in wear and friction compared to dry condition.

  20. Effect of a hard sublayer on contact interaction and wear behavior of electrodeposited gold-based coatings

    Energy Technology Data Exchange (ETDEWEB)

    Lyazgin, Alexander O., E-mail: lyazgin@list.ru, E-mail: shugurov@ispms.tsc.ru, E-mail: pav@ispms.tsc.ru; Shugurov, Artur R., E-mail: lyazgin@list.ru, E-mail: shugurov@ispms.tsc.ru, E-mail: pav@ispms.tsc.ru; Panin, Alexey V., E-mail: lyazgin@list.ru, E-mail: shugurov@ispms.tsc.ru, E-mail: pav@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Shesterikov, Evgeniy V., E-mail: evgen@micran.ru [Research and Production Company Micran, Tomsk, 634034, Russia and National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2014-11-14

    The mechanical properties and wear of electroplated Au–Ni coatings deposited on beryllium bronze substrates with Ni or Ni–B intermediate layers were investigated. It was revealed that the sublayer material has no significant effect on the hardness and the elastic modulus of the coatings. At the same time, the harder sublayer favors localization of plastic deformation and, thus, strain hardening of coatings in the course of tribological tests. The Ni–B sublayer was shown to provide significant wear reduction of Au–Ni coatings as compared with the Ni sublayer.

  1. Axisymmetric fretting analysis in coated cylinder

    Indian Academy of Sciences (India)

    M Ramesh; Satish V Kailas; K R Y Simha

    2008-06-01

    Fretting is essentially a contact fatigue phenomenon, although bulk stresses and material properties contribute to final failure. The near surface state of stress developed under oscillatory contact between machine elements plays a major role in deciding the severity of fretting. It is possible to enhance tribological properties by coating the surface. There is rather scanty literature available on fretting analysis of coated components. Presence of such coatings has a large influence on the near surface state of stress. The effect of coatings on the severity of fretting is the focus of this paper. Results obtained for both hard and soft coatings are compared with the results obtained for the homogeneous case. The component geometry and loading are chosen to be cylindrical to enable 3D elastic axisymmetric fretting analysis. The results are compared with 2D models (strip and half-plane) to examine their utility and validity for understanding axisymmetric fretting. Contact pressure and frictional shear loading cases are solved separately and superposed appropriately depending on the coefficient of friction considered. Results for different values of coefficient of friction and elastic mismatch are illustrated through contour plots of stresses and strains. These results are expected to be helpful for identifying fretting failure zones and fracture mechanisms in coated components. Analytical results presented here could serve as useful benchmarks for calibrating numerical codes and experimental techniques.

  2. Dry Sliding Wear Behavior of A356 Alloy/Mg2Sip Functionally Graded in-situ Composites: Effect of Processing Conditions

    Directory of Open Access Journals (Sweden)

    S.C. Ram

    2016-09-01

    Full Text Available In present study, the effect of dry sliding wear conditions of A356 alloy/Mg2Sip functionally graded in-situ composites developed by centrifugal casting method has been studied. A pure commercial A356 alloy (Al–7.5Si–0.3Mg was selected to be the matrix of the composites and primary Mg2Sip reinforcing particles were formed by in-situ chemical reaction with an average grain size of 40-47.8 µm. The Al–(Mg2Sip functionally graded metal matrix composites (FGMMC’s were synthesized by centrifugal casting technique with radial geometry, using two different mould rotating speeds ( 1200 and 1600 rpm. The X-ray diffraction (XRD characterization technique was carried out to confirm the in-situ formed Mg2Si particles in composites. Optical microscopy examination was carried out to reveals the grain refinement of Al-rich grains due to in-situ formed Mg2Si particles. Scanning electron microscope (SEM and Energy dispersive X-ray spectroscopy (EDS techniques were carried out to reveal the distribution of phases, morphological characteristics and confirmation of primary Mg2Si particles in the matrix. The sliding wear behavior was studied using a Pin-on-Disc set-up machine with sliding wear parameters: effect of loads (N, effect of sliding distances (m and effect of Mg on wear at room temperature with a high-carbon chromium steel disc (HRC-64 as counter surfaces. A good correlation was evidenced between the dry sliding behaviour of functionally graded in-situ composites and the distribution of Mg2Si reinforcing particles. Beside the above processing conditions, the dominant wear mechanisms of functionally graded in-situ composites have been correlated with the microstructures. The hardness and wear resistance properties of these composites increase with increasing volume percent of reinforced primary Si/Mg2Si particles toward inner zone of cast cylindrical shapes. The objective of this works was to study the tribological characteristics under dry sliding

  3. The Impact of Retained Austenite Characteristics on the Two-Body Abrasive Wear Behavior of Ultrahigh Strength Bainitic Steels

    Science.gov (United States)

    Narayanaswamy, Balaji; Hodgson, Peter; Timokhina, Ilana; Beladi, Hossein

    2016-10-01

    In the current study, a high-carbon, high-alloy steel (0.79 pct C, 1.5 pct Si, 1.98 pct Mn, 0.98 pct Cr, 0.24 pct Mo, 1.06 pct Al, and 1.58 pct Co in wt pct) was subjected to an isothermal bainitic transformation at a temperature range of 473 K to 623 K (200 °C to 350 °C), resulting in different fully bainitic microstructures consisting of bainitic ferrite and retained austenite. With a decrease in the transformation temperature, the microstructure was significantly refined from ~300 nm at 623 K (350 °C) to less than 60 nm at 473 K (200 °C), forming nanostructured bainitic microstructure. In addition, the morphology of retained austenite was progressively altered from film + blocky to an exclusive film morphology with a decrease in the temperature. This resulted in an enhanced wear resistance in nanobainitic microstructures formed at low transformation temperature, e.g., 473 K (200 °C). Meanwhile, it gradually deteriorated with an increase in the phase transformation temperature. This was mostly attributed to the retained austenite characteristics ( i.e., thin film vs blocky), which significantly altered their mechanical stability. The presence of blocky retained austenite at high transformation temperature, e.g., 623 K (350 °C) resulted in an early onset of TRIPing phenomenon during abrasion. This led to the formation of coarse martensite with irregular morphology, which is more vulnerable to crack initiation and propagation than that of martensite formed from the thin film austenite, e.g., 473 K (200 °C). This resulted in a pronounced material loss for the fully bainitic microstructures transformed at high temperature, e.g., 623 K (350 °C), leading to distinct sub-surface layer and friction coefficient curve characteristics. A comparison of the abrasive behavior of the fully bainitic microstructure formed at 623 K (350 °C) and fully pearlitic microstructure demonstrated a detrimental effect of blocky retained austenite with low mechanical stability on

  4. Effect of Rhenium Addition on Wear Behavior of Cr-Al2O3 Metal Matrix Composites

    Science.gov (United States)

    Chmielewski, Marcin; Piątkowska, Anna

    2015-05-01

    Materials for applications in the automotive industry are required to be strong, stiff, hard, light weight, and wear resistant, which is very difficult to achieve in the case of conventional materials. To meet all these diverse requirements, it is necessary to combine various types of materials (such as metals and ceramics). In the present study, the chromium and chromium-rhenium matrices were reinforced with aluminum oxide to obtain composite materials with improved wear resistance. The composites were fabricated by a powder metallurgy method. The effects of the rhenium addition and volume fraction of aluminum oxide on the wear rate and the friction coefficient of the composites at room temperature were examined in a ball-on-surface apparatus under dry conditions. The worn surfaces and debris were studied by scanning electron microscopy. The final values of the friction coefficient were 0.9 and 0.8 for the Cr-25%Al2O3 and Cr-40%Al2O3 composites, respectively. Alloying Cr matrix with Re improved wear resistance of composite but, at the same time, it caused an increase in its coefficient of friction.

  5. Microstructure and Wear Behavior of Ti-6Al-4V Treated by Plasma Zr-alloying and Plasma Nitriding

    Institute of Scientific and Technical Information of China (English)

    CHEN Kai; LIU Xiaoping; LIU Xiaozhen; MENG Tianxu; GUO Qi; WANG Zhenxia; LIN Naimin

    2016-01-01

    A duplex treatment of plasma Zr-alloying and plasma nitriding was used to improve the tribological properties of Ti-6Al-4V. The microstructure of the Zr-N composite (alloyed) layer formed on Ti-6Al-4V and its hardness, friction and wear properties were investigated by using OM, SEM, GDOES, EDS, microhardness tester as well as ball-on-disk tribometer. The results of microstructural analysis show that the alloyed layer is compact and uniform and is mainly composed of ZrN, TiN0.3 and AlN. A very tiny adhesive and slight oxidation wear is the primary wear mechanism for the modiifed Ti-6Al-4V. The tribological property is improved signiifcantly after the duplex treatment. The good combination of antifriction and wear resistance for modiifed Ti-6Al-4V is mainly attributed to the higher surface hardness of metal nitrides formed on the surface and enhanced supporting of the Zr-diffusing layer.

  6. Uniform Design of Optimizing Formulation of Friction Materials with Composite Mineral Fiber (CMF) and Their Friction and Wear Behavior

    Science.gov (United States)

    Yang, Yazhou; Jiang, Man; Xu, Jie; Ma, Yunhai; Tong, Jin

    2012-04-01

    In this work, the uniform design method was applied to arrange the experimental scheme for optimizing formulation of friction materials. The friction and wear of the friction materials based on the optimized formulation was carried out on a constant speed friction tester (JF150D-II), using pad-on-disc contact mode against gray cast iron disc. The worn surfaces of the friction materials were examined by scanning electron microscopy (JSM5310) and the friction mechanism was discussed. The results showed that the uniform design method was appropriate for finding the optimum formulation of the friction materials with better properties. Compared with two conventional friction materials, the friction materials based on the optimized formulation possessed higher and stable friction coefficient and higher wear resistance, even at the disc temperature of 350°C. The adhesion, strain fatigue and abrasive wear were the main wear mechanisms of the friction materials. Tribo-chemical phenomenon and plastic deformation existed on the worn surface layer.

  7. Abrasive Wear Behavior of WC Reinforced Ni-BASED Composite Coating Sprayed and Fused by Oxy-Acetylene Flame

    Science.gov (United States)

    Wang, Qun; Chen, Zhenhua; Ding, Zhang Xiong; Chen, Ding

    Microstructure of WC reinforced Ni-based self-fluxing alloy composite coating sprayed and fused by oxy-acetylene flame was investigated by scanning electron microscopy and energy dispersive X-ray Spectrometry, X-ray diffraction, and transmission electron microscopy. The wear performance of the coating was studied by a MLS-225 wet sand rubber wheel abrasive wear tester at various loads and sizes of abrasive particles. Also, the wear resistance of the coating was compared with uncoated ASTM1020 steel. The results indicated that the coating is bonded metallurgically to the substrate and has a homogeneous microstructure composed of both coarse WC and fine carbide and boride grains such as Cr7C3, Cr23C6, and Ni2B which disperse uniformly in the matrix of γ-Ni solid solution and Ni3B. The worn mass loss of the coating and ASTM1020 steel both increased with the load and size of abrasive particles, also, the coating has exhibited excellent abrasive wear resistance compared with ASTM1020 steel.

  8. Understanding and modeling Förster-type resonance energy transfer (FRET) introduction to FRET

    CERN Document Server

    Govorov, Alexander; Demir, Hilmi Volkan

    2016-01-01

    This Brief presents a historical overview of the Förster-type nonradiative energy transfer and a compilation of important progress in FRET research, starting from Förster until today, along with a summary of the current state-of-the-art. Here the objective is to provide the reader with a complete account of important milestones in FRET studies and FRET applications as well as a picture of the current status.

  9. Microstructural Characterization and Wear Behavior of Nano-Boride Dispersed Coating on AISI 304 Stainless Steel by Hybrid High Velocity Oxy-Fuel Spraying Laser Surface Melting

    Science.gov (United States)

    Sharma, Prashant; Majumdar, Jyotsna Dutta

    2015-07-01

    The current study concerns the detailed microstructural characterization and investigation of wear behavior of nano-boride dispersed coating developed on AISI 304 stainless steel by high velocity oxy-fuel spray deposition of nickel-based alloy and subsequent laser melting. There is a significant refinement and homogenization of microstructure with improvement in microhardness due to laser surface melting (1200 VHN as compared to 945 VHN of as-sprayed and 250 VHN of as-received substrate). The high temperature phase stability of the as-coated and laser melted surface has been studied by differential scanning calorimeter followed by detailed phase analysis at room and elevated temperature. There is a significant improvement in wear resistance of laser melted surface as compared to as-sprayed and the as-received one due to increased hardness and reduced coefficient of friction. The mechanism of wear has been investigated in details. Corrosion resistance of the coating in a 3.56 wt pct NaCl solution is significantly improved (4.43 E-2 mm/year as compared to 5 E-1 mm/year of as-sprayed and 1.66 mm/year of as-received substrate) due to laser surface melting as compared to as-sprayed surface.

  10. Thermo-mechanical, Wear and Fracture Behavior of High-density Polyethylene/Hydroxyapatite Nano Composite for Biomedical Applications:Effect of Accelerated Ageing

    Institute of Scientific and Technical Information of China (English)

    H.Fouad; R.Elleithy; Othman Y.Alothman

    2013-01-01

    The objective of this work is to demonstrate how the viscoelastic,thermal,rheological,hardness,wear resistance and fracture behavior of bioinert high-density polyethylene (HDPE) can be changed by the addition of hydroxyapatite (HAP) nano particles.Also the effects of accelerated thermal ageing on the composite properties have been investigated.Different weight fractions of HAP nano particles up to 30 wt% have been incorporated in HDPE matrix by using melt blending in co-rotating intermeshing twin screw extruder.The fracture toughness results showed a remarkable decrease in proportion to the HAP content.The differential scanning calorimetry results indicated that the melting temperature and crystallinity were affected by the addition of HAP nano particles into the matrix.The complex viscosity increased as the percentage of HAP increased due to the restriction of the molecular mobility.The dynamic mechanical analysis results revealed that higher storage modulus (8.3 1011 Pa) could be obtained in the developed HDPE/HAP in 30 wt% compared to neat HDPE (5.1 1011 Pa).Finally,the hardness and wear resistance of HDPE were improved significantly due to the addition of HAP nano particles.The changes in the HDPE and its nano composite properties due to ageing showed that the HDPE and its hang composites crystallinity increased while the fracture toughness,hardness,wear resistance,storage and loss modulus decreased.

  11. Research of Consumer Behavior on Female Home Wear in Shanghai%上海市女性家居服消费行为研究

    Institute of Scientific and Technical Information of China (English)

    于素利

    2013-01-01

    Service questionnaire survey on female consumer purchased home wear in Shanghai based on the consumer’s basic conditions, consumptive habit, the consumer preferences and other aspects, analyzed the consumptive behavior characteristics the domestic female home ware service, summed up the important factors in product design for the home wear and provided suggestions and reference for home wear enterprise to make correctly target market and product design.%从消费者的基本情况、消费行为以及对家居服的喜好等方面,对上海市女性家居服消费者进行问卷调查,分析讨论了国内女性家居服消费者的消费行为特点,总结了家居服设计要素的侧重点,为家居服企业正确确定目标市场和产品设计提供参考。

  12. Answer to the dynamic (fretting effect) and static (oxide) behavior of electric contact surfaces: based on a five-year infrared thermographic study

    Science.gov (United States)

    Paez-Leon, Cristobal D.; Patino, Antonio R.; Aguillon, Luis

    1991-03-01

    This paper describes the results of a five-year study carried out in 38 power substations (230, 115, 34.5 and 13.8 Kv), located in the Western power electric system of CADAFE (Venezuela's national Electric Utility). A total of 154 hot spots were found between 1980 and 1982, a time span considered a reliable source of information in connection with methodology, term and results. The distribution of hot spots found during those years was 77, 33 and 44. The reduction of the spot/substation parameter was found to be 4.1, 3.3 and 3.1, respectively. Every item detected could have been the cause of major interruptions, locally and regionally, or even the system's blackout. The methodology used to determine the major concentration of findings and their location on the equipment, followed the sequence of Pareto's Diagram and Ishikawa's Graphic. Based on the results of the study whose results are presented here, a lubricant and compound-aid connector for Al-Al and bimetallic electric connections was formulated, developed, manufactured, tested (at IREQ laboratories) and traded (CONECTECH CAC- 01). To date, the whole process represents 12 years of work. The connector's behavior and reliability are being tested throughout Venezuela's national electric system (responsible for the supply of around 50,000 Gwh/year) with the use of 12 Tons of CONECTECH CAC-01.

  13. Fretting fatigue crack propagation rate under variable loading conditions

    Directory of Open Access Journals (Sweden)

    C. Gandiolle

    2016-01-01

    Full Text Available Fretting fatigue experiments aim to represent industrial problems and most of them endure variable loading. Being able to assess lifetime of assemblies, especially for low propagation rate conditions, is essential as experimental validation is often too expensive. Both experimental and numerical approaches are proposed to follow the crack propagation rate of steel on steel cylinder/plane fretting fatigue contact submitted to variable loading conditions. An original experimental monitoring has been implemented on the fretting-fatigue test device to observe crack propagation using a potential drop technique. A calibration curve relating crack length and electrical potential was established for the studied contact. It allows direct knowledge of the crack length and crack propagation rate. It was applied to mixed load test showing crack arrest for the last loading condition. To explain this behavior, a 2-dimensional FE modeling was implemented to simulate the complexes multi-axial contact stressing. The crack propagation rate was formalized using an effective stress intensity factor amplitude ΔKeff coupled with Paris law of the material. The crack arrest condition for a given loading was related to ΔKeff along the expected crack path crossing the material crack arrest threshold ΔK0. The failure was related to ΔKeff reaching the critical stress intensity factor KIC. A good correlation with experiments was observed allowing to predict the crack arrest condition although the model tends to overestimate the final crack length extension.

  14. Heat Treatment Parameters to Optimize Friction and Wear behavior of Novel Hybrid Aluminium Composites Using Taguchi Technique

    Directory of Open Access Journals (Sweden)

    V.C.Uvaraja

    2014-05-01

    Full Text Available In the present study, an Al 7075 alloy is used as the matrix and varying weight percentage of Silicon Carbide (SiC and constant weight percentage of Boron Carbide (B4C as the reinforcing material. The composite is produced using stir casting technique. The composite thus formed is termed as hybrid composite. The samples are prepared for heat treatment process by subjecting to solutionizing temperature of 530o C for 1 hr followed by quenching in water. Further the specimens are subjected to artificial aging for durations of 4, 6 and 8 hr at a temperature of 175°C. The mechanical and tribological properties of composites before and after heat treatment are examined by Vickers hardness test machine and pin-on-disc test machine respectively. The wear rate and friction co-efficient of heat treatment parameters are evaluated based on Taguchi technique. The analysis is further extended to the optimization of test parameters using Design of Experiment (DoE based on L9 orthogonal array. The developed Analysis of Variance (ANOVA and the regression equations is obtained through MINITAB R16 are used to investigate the influence of parameters like sliding speed, applied load, sliding time, and percentage of reinforcement on the dry sliding wear and friction co-efficient of the composites. The wear surface morphology and wear mechanism of the pins are investigated using Scanning Electron Microscope (SEM and are correlated them with wear test results. Finally, confirmation tests are carried out to verify the experimental results.

  15. Microstructure, Mechanical Properties, and Two-Body Abrasive Wear Behavior of Cold-Sprayed 20 vol.% Cubic BN-NiCrAl Nanocomposite Coating

    Science.gov (United States)

    Luo, Xiao-Tao; Yang, Er-Juan; Shang, Fu-Lin; Yang, Guan-Jun; Li, Chen-Xin; Li, Chang-Jiu

    2014-10-01

    20 vol.% cubic boron nitride (cBN) dispersoid reinforced NiCrAl matrix nanocomposite coating was prepared by cold spray using mechanically alloyed nanostructured composite powders. The as-sprayed nanocomposite coating was annealed at a temperature of 750 °C to enhance the inter-particle bonding. Microstructure of spray powders and coatings was characterized. Vickers microhardness of the coatings was measured. Two-body abrasive wear behavior of the coatings was examined on a pin-on-disk test. It was found that, in mechanically alloyed composite powders, nano-sized and submicro-sized cBN particles are uniformly distributed in nanocrystalline NiCrAl matrix. Dense coating was deposited by cold spray at a gas temperature of 650 °C with the same phases and grain size as those of the starting powder. Vickers hardness test yielded a hardness of 1063 HV for the as-sprayed 20 vol.% cBN-NiCrAl coating. After annealed at 750 °C for 5 h, unbonded inter-particle boundaries were partially healed and evident grain growth of nanocrystalline NiCrAl was avoided. Wear resistance of the as-sprayed 20 vol.% cBN-NiCrAl nanocomposite coating was comparable to the HVOF-sprayed WC-12Co coating. Annealing of the nanocomposite coating resulted in the improvement of wear resistance by a factor of ~33% owing to the enhanced inter-particle bonding. Main material removal mechanisms during the abrasive wear are also discussed.

  16. Ultra-High Molecular Weight Polyethylene: Influence of the Chemical, Physical and Mechanical Properties on the Wear Behavior. A Review

    Directory of Open Access Journals (Sweden)

    Pierangiola Bracco

    2017-07-01

    Full Text Available Ultra-high molecular weight polyethylene (UHMWPE is the most common bearing material in total joint arthroplasty due to its unique combination of superior mechanical properties and wear resistance over other polymers. A great deal of research in recent decades has focused on further improving its performances, in order to provide durable implants in young and active patients. From “historical”, gamma-air sterilized polyethylenes, to the so-called first and second generation of highly crosslinked materials, a variety of different formulations have progressively appeared in the market. This paper reviews the structure–properties relationship of these materials, with a particular emphasis on the in vitro and in vivo wear performances, through an analysis of the existing literature.

  17. Microstructure and wear behavior of laser cladding Ni-based alloy composite coating reinforced by Ti(C,N) particulates

    Institute of Scientific and Technical Information of China (English)

    Qi Yongtian; Shi Hanchao; Zou Zengda; Hu Liping

    2008-01-01

    In this paper, Ni-based alloy composite coating reinforced by Ti (C,N) particles was fabricated on the mild steel through laser cladding technology. The microstructure of laser cladding layer was analyzed by means of optical microscopy (OM),X-ray diffraction (XRD) and scanning electron microscopy (SEM).The wear resistance test of the coating was evaluated using an M-2000 tester. The results showed that the Ni-based composite coating had an ability of rapid solidification to form dendritic crystals microstructure consisting of Ti (C,N) particulates uniformly distributed in the matrix. It was found that some Ti(C,N) particles are similar to be round in shape, and the others are irregular. Laser cladding layer reinforced by Ti(C,N) particulates was found to possess good wear resistance property.

  18. Erosive Wear Behavior of Nickel-Based High Alloy White Cast Iron Under Mining Conditions Using Orthogonal Array

    Science.gov (United States)

    Yoganandh, J.; Natarajan, S.; Babu, S. P. Kumaresh

    2013-09-01

    Nihard Grade-4, a nickel-bearing cast iron widely used in slurry pumps and hydrodynamic components, is evaluated for its erosive wear response under mining conditions using a statistical approach. Experiments were conducted by varying the factors namely velocity, slurry concentration, angle of impingement, and pH in three levels, using L9 orthogonal array. Analysis of variance was used to rank the factors influencing erosive wear. The results indicate that velocity is the most influencing factor followed by the angle of impingement, slurry concentration, and pH. Interaction effects of velocity, slurry concentration, angle of impingement, and pH on erosion rate have been discussed. Wear morphology was also studied using SEM characterization technique. At lower angle (30°) of impingement, the erosion of material is by micro fracture and shallow ploughing with the plastic deformation of the ductile austenitic matrix. At the normal angle (90°) of impingement, the material loss from the surface is found because of deep indentation, forming protruded lips which are removed by means of repeated impact of the erodent.

  19. Effect of the content of B4C on microstructural evolution and wear behaviors of the laser-clad coatings fabricated on Ti6Al4V

    Science.gov (United States)

    Bai, L. L.; Li, J.; Chen, J. L.; Song, R.; Shao, J. Z.; Qu, C. C.

    2016-01-01

    TiNi/Ti2Ni-based composite coatings reinforced by TiC and TiB2 were produced on Ti6Al4V by laser cladding the mixture of a Ni-based alloy and different contents of B4C (0 wt%, 5 wt%, 15 wt%, and 25 wt%). The macromorphologies and microstructures of the coatings were examined through optical microscopy, X-ray diffractometry, scanning electron microscopy, and energy dispersive spectrometry. The microhardness, fracture toughness, and wear behaviors of the coatings were also investigated by using a microhardness tester and an ultra-functional wear testing machine. Results showed that the coatings were mainly composed of TiNi/Ti2Ni and TiC/TiB2 as the matrix and reinforcement particles, respectively. The phase constituents of the coatings were not influenced by addition of different contents of B4C. The microstructure of the reinforcements in the coatings presented the following evolution: hypereutectic consisting of blocky (TiC+TiB2)e eutectic and primary TiCp cellular dendrites (0 wt% B4C), mixture of hypereutectic and willow-shaped (TiB2+TiC)p pseudoeutectic (5 wt% B4C), and pseudoeutectic (15 and 25 wt% B4C). With increasing B4C content, the volume fraction and size of the pseudoeutectic structures as well as the average microhardness of the coatings (850, 889, 969, and 1002 HV0.2) were increased. By contrast, the average fracture toughness of the coatings was gradually decreased (4.47, 4.21, 4.06, and 3.85 Mpa m1/2) along with their wear volumes (0 wt%, 5 wt%, and 15 wt% B4C). The increase in B4C content to 25 wt% did not further reduce wear loss. The wear mechanism transformed from micro-cutting (0 wt% B4C) into a combination of micro-cutting and brittle debonding (5 wt% B4C) and finally led to brittle debonding (15 wt% and 25 wt% B4C). Coatings with suitable contents of B4C (less than 15 wt%) showed excellent comprehensive mechanical properties.

  20. Tribo-Mechanisms of Carbon Nanotubes: Friction and Wear Behavior of CNT-Reinforced Nickel Matrix Composites and CNT-Coated Bulk Nickel

    Directory of Open Access Journals (Sweden)

    Leander Reinert

    2016-04-01

    Full Text Available In this study, nickel matrix composites reinforced by carbon nanotubes (CNTs are compared to unreinforced CNT-coated (by drop-casting bulk nickel samples in terms of their friction and wear behavior, thus gaining significant knowledge regarding the tribological influence of CNTs and the underlying tribo-mechanism. It has been shown that the frictional behavior is mainly influenced by the CNTs present in the contact zone, as just minor differences in the coefficient of friction between the examined samples can be observed during run-in. Consequently, the known effect of a refined microstructure, thus leading to an increased hardness of the CNT reinforced samples, seems to play a minor role in friction reduction compared to the solid lubrication effect induced by the CNTs. Additionally, a continuous supply of CNTs to the tribo-contact can be considered isolated for the reinforced composites, which provides a long-term friction reduction compared to the CNT-coated sample. Finally, it can be stated that CNTs can withstand the accumulated stress retaining to some extent their structural state for the given strain. A comprehensive study performed by complementary analytical methods is employed, including Raman spectroscopy and scanning electron microscopy to understand the involved friction and wear mechanisms.

  1. pH sensitivity of FRET reporters based on cyan and yellow fluorescent proteins.

    Science.gov (United States)

    Betolngar, Dahdjim-Benoît; Erard, Marie; Pasquier, Hélène; Bousmah, Yasmina; Diop-Sy, Awa; Guiot, Elvire; Vincent, Pierre; Mérola, Fabienne

    2015-05-01

    It is generally acknowledged that the popular cyan and yellow fluorescent proteins carried by genetically encoded reporters suffer from strong pH sensitivities close to the physiological pH range. We studied the consequences of these pH responses on the intracellular signals of model Förster resonant energy transfer (FRET) tandems and FRET-based reporters of cAMP-dependent protein kinase activity (AKAR) expressed in the cytosol of living BHK cells, while changing the intracellular pH by means of the nigericin ionophore. Although the simultaneous pH sensitivities of the donor and the acceptor may mask each other in some cases, the magnitude of the perturbations can be very significant, as compared to the functional response of the AKAR biosensor. Replacing the CFP donor by the spectrally identical, but pH-insensitive Aquamarine variant (pK1/2 = 3.3) drastically modifies the biosensor pH response and gives access to the acid transition of the yellow acceptor. We developed a simple model of pH-dependent FRET and used it to describe the expected pH-induced changes in fluorescence lifetime and ratiometric signals. This model qualitatively accounts for most of the observations, but reveals a complex behavior of the cytosolic AKAR biosensor at acid pHs, associated to additional FRET contributions. This study underlines the major and complex impact of pH changes on the signal of FRET reporters in the living cell.

  2. Action-FRET of a Gaseous Protein

    Science.gov (United States)

    Daly, Steven; Knight, Geoffrey; Halim, Mohamed Abdul; Kulesza, Alexander; Choi, Chang Min; Chirot, Fabien; MacAleese, Luke; Antoine, Rodolphe; Dugourd, Philippe

    2017-01-01

    Mass spectrometry is an extremely powerful technique for analysis of biological molecules, in particular proteins. One aspect that has been contentious is how much native solution-phase structure is preserved upon transposition to the gas phase by soft ionization methods such as electrospray ionization. To address this question—and thus further develop mass spectrometry as a tool for structural biology—structure-sensitive techniques must be developed to probe the gas-phase conformations of proteins. Here, we report Förster resonance energy transfer (FRET) measurements on a ubiquitin mutant using specific photofragmentation as a reporter of the FRET efficiency. The FRET data is interpreted in the context of circular dichroism, molecular dynamics simulation, and ion mobility data. Both the dependence of the FRET efficiency on the charge state—where a systematic decrease is observed—and on methanol concentration are considered. In the latter case, a decrease in FRET efficiency with methanol concentration is taken as evidence that the conformational ensemble of gaseous protein cations retains a memory of the solution phase conformational ensemble upon electrospray ionization.

  3. Microstructure and erosive wear behaviors of Ti6Al4V alloy treated by plasma Ni alloying

    Science.gov (United States)

    Wang, Z. X.; Wu, H. R.; Shan, X. L.; Lin, N. M.; He, Z. Y.; Liu, X. P.

    2016-12-01

    The Ni modified layers were prepared on the surface of Ti6Al4V substrate by the plasma surface alloying technique. The surface and cross-section morphology, element concentration and phase composition were investigated by thermal field emission scanning electron microscopy (SEM), and glow discharge optical emission spectroscopy (GDOES), X-ray diffraction (XRD), respectively. The cross-section nano-scale hardness of the Ni modified layer was measured by nanoindenter. The results showed that the Ni modified layers exhibited triple-layer structure and continuous gradient distribution of the concentration. From the surface to the matrix, they were 2 μm Ni deposition layer, 8 μm Ni-rich alloying layer including the phases of Ni3Ti, NiTi, Ti2Ni, AlNi3 and 24 μm Ni-poor alloying layer forming the solid solution of nickel. With increasing of the thickness of the Ni modified layer, the microhardness increased first, reached the climax, then gradient decreased. The erosion tests were performed on the surfaces of the untreated and treated Ti6Al4V samples using MSE (Micro-slurry-jet Erosion) method. The experiment results showed that the wear rate of every layer showed different values, and the Ni-rich alloying layer was the lowest. The strengthening mechanism of the Ni modified layer showed micro-cutting wearing.

  4. Anodizing Effect on the Wear and Corrosion Behavior of EN AC-46500 Components Produced by Semi-Solid Rheocasting (SSR)

    Science.gov (United States)

    Forn, A.; Baile, M. T.; Picas, J. A.; Martín, E.; Menargues, S.

    2011-05-01

    In this work the effect of the anodizing process on the surface properties of SSR components was investigated. EN AC-46500 aluminium alloy components were formed using a 700 Ton high pressure machine and an Idra Semi Solid Rheocasting Station (SSR). The samples were heat treated with the aim of modifying the form and distribution of the eutectic silicon phase and after the heat treatment they were shotpeened in different conditions to obtain different surface roughness. Finally, the components were anodized with the purpose of improving the tribological properties and corrosion resistance. Surface modifications were investigated as they might have beneficial effects on the wear and corrosion behaviour. Experiments using a tribometer (ball on disc configuration) were performed in order to evaluate the tribological properties of the material and salt spray corrosion tests were used to study the corrosion resistance. These studies were carried out before and after the anodizing process. The anodized components show a significant improvement of the corrosion and wear resistance under the tested conditions, in spite of the high percentage of intermetallics compounds present in the AC-46500 alloy.

  5. Development of in-Situ Al-Si/CuAl2 Metal Matrix Composites: Microstructure, Hardness, and Wear Behavior

    Directory of Open Access Journals (Sweden)

    Mahmoud M. Tash

    2016-06-01

    Full Text Available In the present work, in-situ metal matrix composites were fabricated through squeeze casting. The copper particles were dispersed with different weight percentages (3%, 6%, 10%, and 15% into Al-12% Si piston alloy. Also, heat treatments were performed at 380 °C and 450 °C for holding times of 6 and 18 h. The microstructures, X-ray diffractometer (XRD pattern, hardness, and wear characteristics were evaluated. The results showed that these copper particles have reacted with the aluminum under all of the aforementioned processing conditions resulting in the formation of fine copper aluminide intermetallics. Most of the intermetallics were CuAl2, while AlCu appeared in a small ratio. Additionally, these intermetallics were homogenously distributed within the alloy matrix with up to 6% Cu addition. The amounts of those intermetallics increased after performing heat treatment. Most of these intermetallics were CuAl2 at 380 °C, while the Cu-rich intermetallics appeared at 450 °C. Increasing the holding time to 18 h, however, led to grain coarsening and resulted in the formation of some cracks. The hardness of the resulting composite materials was improved. The hardness value reached to about 170 HV after heat treating at 380 °C for 8 h. The wear resistance of the resulting composite materials was remarkably improved, especially at lower additions of Cu and at the lower heat treatment temperature.

  6. Rolling Contact Fatigue and Wear Behavior of High-Performance Railway Wheel Steels Under Various Rolling-Sliding Contact Conditions

    Science.gov (United States)

    Faccoli, Michela; Petrogalli, Candida; Lancini, Matteo; Ghidini, Andrea; Mazzù, Angelo

    2017-07-01

    An experimental investigation was carried out to study and compare the response to cyclic loading of the high-performance railway wheel steels ER8 EN13262 and SUPERLOS®. Rolling contact tests were performed with the same contact pressure, rolling speed and sliding/rolling ratio, varying the lubrication regime to simulate different climatic conditions. The samples, machined out of wheel rims at two depths within the reprofiling layer, were coupled with UIC 900A rail steel samples. The wear rates, friction coefficients and hardness were correlated with the deformation beneath the contact surface. The crack morphology was studied, and the damage mechanisms were identified. The distribution of crack length and depth at the end of the dry tests was analyzed to quantify the damage. The main difference between the steels lies in the response of the external samples to dry contact: SUPERLOS® is subjected to a higher wear and lower friction coefficient than ER8, and this reduces the density of surface cracks that can propagate under wet contact conditions. The analysis of feedback data from in-service wheels confirmed the experimental results.

  7. Development of in-Situ Al-Si/CuAl2 Metal Matrix Composites: Microstructure, Hardness, and Wear Behavior

    Science.gov (United States)

    Tash, Mahmoud M.; Mahmoud, Essam R. I.

    2016-01-01

    In the present work, in-situ metal matrix composites were fabricated through squeeze casting. The copper particles were dispersed with different weight percentages (3%, 6%, 10%, and 15%) into Al-12% Si piston alloy. Also, heat treatments were performed at 380 °C and 450 °C for holding times of 6 and 18 h. The microstructures, X-ray diffractometer (XRD) pattern, hardness, and wear characteristics were evaluated. The results showed that these copper particles have reacted with the aluminum under all of the aforementioned processing conditions resulting in the formation of fine copper aluminide intermetallics. Most of the intermetallics were CuAl2, while AlCu appeared in a small ratio. Additionally, these intermetallics were homogenously distributed within the alloy matrix with up to 6% Cu addition. The amounts of those intermetallics increased after performing heat treatment. Most of these intermetallics were CuAl2 at 380 °C, while the Cu-rich intermetallics appeared at 450 °C. Increasing the holding time to 18 h, however, led to grain coarsening and resulted in the formation of some cracks. The hardness of the resulting composite materials was improved. The hardness value reached to about 170 HV after heat treating at 380 °C for 8 h. The wear resistance of the resulting composite materials was remarkably improved, especially at lower additions of Cu and at the lower heat treatment temperature. PMID:28773564

  8. Characterization and Wear Behavior of Heat-treated Ni3Al Coatings Deposited by Air Plasma Spraying

    Science.gov (United States)

    Mehmood, K.; Rafiq, M. A.; Nusair Khan, A.; Ahmed, F.; Mudassar Rauf, M.

    2016-07-01

    Air plasma spraying was utilized to deposit Ni3Al coatings on AISI-321 steel substrate. The deposited coatings were isothermally heat-treated at various temperatures from 500 to 800 °C for 10, 30, 60, and 100 h. The x-ray diffraction analysis revealed NiO formation in Ni3Al at 500 °C after 100 h, and the percentage of NiO increased with increasing exposure time and temperature. The hardness of the coating increased with the formation of NiO. The DSC test showed the formation of minor phases, Al3Ni and Al3Ni2, within the coating along with the major phase Ni3Al. TGA revealed a slowing down of the oxidation rate upon surface oxide formation. The pin-on-disk wear test on the as-sprayed and heat-treated coatings showed that wear rate and coefficient of friction decreased with an increase in the NiO phase content.

  9. Bio-derived Fuel Blend Dilution of Marine Engine Oil and Imapct on Friction and Wear Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Ajayi, Oyelayo O.; Lorenzo-Martin, Cinta; Fenske, George R.; Corlett, John; Murphy, Chris; Przesmitzki, Steve

    2016-04-01

    To reduce the amount of petroleum-derived fuel used in vehicles and vessels powered by internal combustion engines, the addition of bio-derived fuel extenders is a common practice. Ethanol is perhaps the most common bio-derived fuel used for blending, and butanol is being evaluated as a promising alternative. The present study determined the fuel dilution rate of three lubricating oils (E0, E10, and i-B16) in a marine engine operating in on-water conditions with a start-and-stop cycle protocol. The level of fuel dilution increased with the number of cycles for all three fuels. The most dilution was observed with i-B16 fuel, and the least with E10 fuel. In all cases, fuel dilution substantially reduced the oil viscosity. The impacts of fuel dilution and the consequent viscosity reduction on the lubricating capability of the engine oil in terms of friction, wear, and scuffing prevention were evaluated by four different tests protocols. Although the fuel dilution of the engine oil had minimal effect on friction, because the test conditions were under the boundary lubrication regime, significant effects were observed on wear in many cases. Fuel dilution also was observed to reduce the load-carrying capacity of the engine oils in terms of scuffing load reduction.

  10. 干摩擦条件下树脂刹车片磨损机制研究%Research on Wear Behavior of Resin Brake Pads under Dry Sliding

    Institute of Scientific and Technical Information of China (English)

    潘道元; 张育增; 刘健; 高中学; 王其兵

    2014-01-01

    To improve the wear resistance of resin brake pads made of resin and brass in the towing engine,the wear be-havior of Brass and Brass/Resin blends was investigated in the MPV-600 type abrasive wear tester under dry sliding.Worn morphology of the brake pad surface was observed using the stereo microscope in order to analyze the wear mechanism.Ex-perimental results show that the decrease in hardness and the change in wear mechanism because of the temperature rise caused by frictional heat are the main reason of the wear of resin brake pads under dry friction.Brass/Resin blends has better heat resistance and wear resistance than Brass sample.The friction coefficient of the friction pairs of resin brake pads and steel is mainly determined by copper mesh material.The wear mechanism is abrasive wear and oxidative wear for the friction pairs of Brass/Resin blends and 45 steel,and abrasive wear and abrasive wear for the friction pairs of brass and 45 steel under dry sliding.%为了优化拖缆机刹车部件的设计参数,同时进一步提高刹车片的耐磨性能,采用MPV-600型磨粒磨损试验机研究无石棉树脂摩擦片和黄铜试样与45#钢配副在干摩擦条件下的摩擦学性能,利用体式显微镜观察试样的磨损形貌并分析其磨损机制。结果表明:摩擦热引起的温升导致的硬度下降及磨损机制的改变是干摩擦条件下摩擦片磨损的主要原因;树脂刹车片的耐热性能、耐磨性能均好于黄铜试样,树脂刹车片与钢配副的摩擦因数主要是由树脂刹车片中的铜纤维材料决定的;干摩擦条件下树脂摩擦片的磨损机制是以磨粒磨损和氧化磨损为主,而黄铜试样以磨粒磨损和黏着磨损为主。

  11. Comportamiento del hierro nodular austemperizado en condiciones de corrosión y desgaste // Behavior of austempered ductile iron under wear and corrosion conditions

    Directory of Open Access Journals (Sweden)

    L. Goyos Pérez

    1999-07-01

    Full Text Available Los hierros nodulares en general y los austemperizados en particular han sido usados con cada vez mayor frecuencia debido asus relevantes propiedades mecánicas en comparación con su costo.En el presente trabajo se valora el comportamiento del hierro nodular ante el trabajo en condiciones de desgaste y corrosión,luego de ser sometido a diferentes tratamientos de austemperizado.Fueron usados un hierro nodular aleado con níquel y molibdeno y otro no aleado. Ambos hierros fueron sometidos a diferentestratamientos de austemperización con mantenimientos isotérmicos a temperaturas entre 250°C y 425°C por tiempos entre 15 y180 minutos.Las muestras tratadas fueron sometidas a ensayos de desgaste por fricción en condiciones no lubricadas determinando laspendientes de desgaste uniforme para cada caso. La resistencia a la corrosión fue determinada mediante el métodopotenciométrico usando como medio el jugo de caña sintético.A partir de los resultados obtenidos se valora la influencia de los diferentes tratamientos sobre las propiedades estudiadas y sedeterminan los más efectivos desde el punto de vista técnico económico.Palabras claves: Hierro nodular, corrosión, desgaste, austemperizado.____________________________________________________________________________AbstractNodular irons and particularly austempered ductile iron has been used more and more due to their excellent mechanicalproperties in comparison with their cost.Presently work deals on behavior of nodular iron working under wear and corrosion conditions, after being submitted todifferent austempered treatments.A nodular iron alloyed with nickel and molybdenum were used as well as a not alloyed one. Both irons were treated underdifferent austempered treatment combinations using isothermal maintenance to temperatures between 250°C and 425°C andspending times between 15 and 180 minutes.Samples were submitted to non-lubricated wear using a “pin on disk” method evaluating the

  12. FRET in membrane biophysics: an overview

    Directory of Open Access Journals (Sweden)

    Luis MS Loura

    2011-11-01

    Full Text Available Förster resonance energy transfer (FRET, in most applications used as a spectroscopicruler, allows an easy determination of the donor-acceptor intermolecular distance.However, the situation becomes complex in membranes, since around each donor there isan ensemble of acceptors at non-correlated distances. In this review, state-of-the-artmethodologies for this situation are presented, usually involving time-resolved data andmodel fitting. This powerful approach can be used to study the occurrence of phaseseparation (rafts or other type of domains, allowing their detection as well as sizeevaluation. Formalisms for studying lipid-protein and protein-protein interactionsaccording to specific topologies are also addressed. The advantages and addedcomplexity of a specific type of FRET (energy homo-transfer or energy migration aredescribed, as well as applications of FRET under the microscope.

  13. Single Molecule Sensitive FRET in Attoliter Droplets

    CERN Document Server

    Milas, Peker; Gamari, Ben D; Goldner, Lori S

    2013-01-01

    Single molecular-pair fluorescence resonance energy transfer (spFRET) has become an cross-disciplinary tool for understanding molecular folding and interactions. While providing detailed information about the individual members of a molecular ensemble, this technique is always limited by fluorophore brightness and stability. In the case of diffusing molecules, the experiment is further limited by the number of photons that can be collected during the time it takes for a molecule to diffuse across the detection volume. To maximize the number of photons it is common to either increase the detection volume at the expense of increased background, or increase the diffusion time by adding glycerol or sucrose to increase viscosity. Here we demonstrate that FRET from attoliter volume (100 nm radius) aqueous droplets in perfluorinated oil has significantly higher signal-to-noise and a much wider dynamic range than FRET from molecules diffusing in solution. However, our measurements also reveal a droplet environment th...

  14. Microstructure and Wear Behavior Of as Cast Al-25mg2si-2cu-2ni Alloy

    Directory of Open Access Journals (Sweden)

    1Geetanjali.S.Guggari ,

    2015-09-01

    Full Text Available The remarkable feature of the Aluminium is its low density and ability to withstand corrosion effect due to phenomenon of passivation. Structural components made from Aluminium and its alloys are vital to the aerospace industry and are important in other areas of transportation and structural materials. The oxides and sulphate are useful compounds of Aluminium based on its weight. In this work, an attempt has been made to utilize the combined effect of high cooling rate solidification, unique micro structural evolution mechanism of T6 heat treatment the advantages of hypereutectic Al-Si system alloyed with other elements such as Cu, Fe and Mg. In the present investigation, the binary alloys in the hypereutectic range viz. Al25Mg2Si has been selected as heat resistant Al-Si alloys. A systematic approach has been carried out to explore the micro structural features, mechanical and wear properties of as cast alloys.

  15. [Wear and different restorative materials--a review].

    Science.gov (United States)

    Beyth, N; Sharon, E; Lipovetsky, M; Smidt, A

    2006-07-01

    Wear of materials is a complex and unpredictable phenomenon. The variables affecting the mechanism of wear include the properties of the two contacting materials and the surrounding and interfacial media. This paper reviews the dental wear of different restorative materials and their counter effect on the tooth structure. It presents the updated classifications for tooth surface lesions termed dental wear, and discusses the wear behavior of various restorative materials. Some guidelines for restorative material selection are given. Clinical wear bears a multifactorial etiology, understanding the mechanism of action is an important step in an appropriate restoration material selection. Each material selected should meet the individual wear behavior and needs. Individual factors may enhance the wear rates: aggressive tooth brushing, parafunctions, diet, acidic/aqueous environment, surface geometry, and diminished tooth support. Supportive treatment following restoration is important to monitor wear rates.

  16. CASL Structural Mechanics Modeling of Grid-to-Rod Fretting (GTRF)

    Science.gov (United States)

    Lu, Wei; Thouless, M. D.; Hu, Zupan; Wang, Hai; Ghelichi, Ramin; Wu, Chen-Hung; Kamrin, Ken; Parks, David

    2016-09-01

    Fluid-induced grid-to-rod fretting (GTRF) wear is responsible for over 70% of fuel leaks in pressurized water reactors (PWRs) in the US. The Consortium for Advanced Simulation of Light Water Reactors (CASL) has identified GTRF as a challenge problem that is very important to nuclear plants. GTRF is a complex problem that involves multiple physical phenomena. This paper summarizes several GTRF-related problems being addressed by the University of Michigan and the Massachusetts Institute of Technology, CASL partners. These include analyses of cladding creep, wear, structural mechanics, and the effects of the rod-to-grid gap. Also outlined are additional aspects of material science and computational modeling that will be needed to realize the ultimate goal of high-fidelity predictive modeling and design tools to address GTRF.

  17. CTAB enhancement of FRET in DNA structures.

    Science.gov (United States)

    Oh, Taeseok; Takahashi, Tsukasa; Kim, Sejung; Heller, Michael J

    2016-01-01

    The effect of cetyl-trimethylammonium bromide (CTAB) on enhancing the fluorescence resonance energy transfer (FRET) between two dye-conjugated DNA strands was studied using fluorescence emission spectroscopy and dynamic light scattering (DLS). For hybridized DNA where one strand is conjugated with a TAMRA donor and the other with a TexasRed acceptor, increasing the concentration of CTAB changes the fluorescence emission properties and improves the FRET transfer efficiency through changes in the polarity of the solvent, neutralization of the DNA backbone and micelle formation. For the DNA FRET system without CTAB, the DNA hybridization leads to contact quenching between TAMRA donor and TexasRed acceptor producing reduced donor emission and only a small increase in acceptor emission. At 50 µM CTAB, however, the sheathing and neutralization of the dye-conjugated dsDNA structure significantly reduces quenching by DNA bases and dye interactions, producing a large increase in FRET efficiency, which is almost four fold higher than without CTAB.

  18. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  19. Microstructure and Wear Behaviors of In-situ Al2O3p/7075 Composites%原位Al2O3P/7075复合材料微观组织与磨损行为

    Institute of Scientific and Technical Information of China (English)

    刘慧敏; 杨树青; 许萍; 李进福

    2012-01-01

    采用原位反应近液相线铸造法制备具有不同质量分数的Al2O3P/7075复合材料,并对其进行干滑动磨损实验研究,通过OM,SEM,TEM等材料分析方法测试了材料的微观组织和磨损表面形貌.结果表明,原位Al2O3颗粒对7075铝合金的晶粒组织有明显细化效果,Al2O3P/7075复合材料的耐磨性比基体7075铝合金有明显的提高.原因是原位合成的复合材料界面结合良好,原位Al2O3颗粒在摩擦过程中起着抑制金属流动和支撑的双重作用.磨损表面形貌显示,原位Al2O3颗粒的加入,使磨损机制由黏着磨损变为磨粒磨损,从而改善了材料的耐磨性.%The Al2O3P/7075 Al composites were synthesized by in-situ reaction near-liquidus casting. The microstructure and dry sliding wear behavior of the prepared composites were analyzed using OM, SEM and TEM as well as wear friction testing. The results reveal that in-situ Al2O3 particle with average size of approximately <1μm is uniformly distributed in the matrix, which exhibits desirable refining effects on microstructure of 7075 Al alloy. The wear behavior of the composites is greatly superior to that of the matrix, which is attributed to the grain refining and formation of a compact interface of Al2O3P/7075 Al composites. In addition, in-situ Al2O3 particles exhibit coupling effects of inhibiting metal flow and bearing some load in process of friction. The wear mechanism of the matrix 7075A1 alloy is adhesive wear, while the wear surface of Al2O3p/7075 Al composites is superior to that of the matrix 7075 Al alloy. The wear mechanism of Al2O3P/7075 Al composites is abrasive wear, and wear resistance of Al2O3P/7075 Al is improved.

  20. Wear-resistant and electromagnetic absorbing behaviors of oleic acid post-modified ferrite-filled epoxy resin composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenjie; Zang, Chongguang, E-mail: zangchongguang@bit.edu.cn; Jiao, Qingjie

    2015-03-15

    The post-modified Mn–Zn ferrite was prepared by grafting oleic acid on the surface of Mn–Zn ferrite to inhibit magnetic nanoparticle aggregation. Fourier Transform Infrared (FT-IR) spectroscopy was used to characterize the particle surfaces. The friction and electromagnetic absorbing properties of a thin coating fabricated by dispersing ferrite into epoxy resin (EP) were investigated. The roughness of the coating and water contact angle were measured using the VEECO and water contact angle meter. Friction tests were conducted using a stainless-steel bearing ball and a Rockwell diamond tip, respectively. The complex permittivity and complex permeability of the composite coating were studied in the low frequency (10 MHz–1.5 GHz). Surface modified ferrites are found to improve magnetic particles dispersion in EP resulting in significant compatibility between inorganic and organic materials. Results also indicate that modified ferrite/EP coatings have a lower roughness average value and higher water contact angle than original ferrite/EP coatings. The enhanced tribological properties of the modified ferrite/EP coatings can be seen from the increased coefficient value. The composite coatings with modified ferrite are observed to exhibit better reflection loss compared with the coatings with original ferrite. - Highlights: • The post-modified Mn-Zn ferrite was prepared by grafting oleic acid on its surface to inhibit aggregation. • The increasing in hydrophobicity and dispersion of modified coating improved compatibility between illers and polymer. • The modified fillers can decrease the friction COF of the composite coatings resulting in the enhanced resistance to wear. • The modified ferrite coatings are observed to exhibit better reflection loss compared with coatings with original ferrite.

  1. Friction Induced Wear of Rapid Prototyping Generated Materials: A Review

    Directory of Open Access Journals (Sweden)

    A. Tsouknidas

    2011-01-01

    Full Text Available Additive manufacturing has been introduced in the early 80s and has gained importance as a manufacturing process ever since. Even though the inception of the implicated processes predominantly focused on prototyping purposes, during the last years rapid prototyping (RP has emerged as a key enabling technology for the fabrication of highly customized, functionally gradient materials. This paper reviews friction-related wear phenomena and the corresponding deterioration mechanisms of RP-generated components as well as the potential of improving the implicated materials' wear resistance without significantly altering the process itself. The paper briefly introduces the concept of RP technologies and the implicated materials, as a premises to the process-dependent wear progression of the generated components for various degeneration scenarios (dry sliding, fretting, etc..

  2. Anomalous surplus energy transfer observed with multiple FRET acceptors.

    Directory of Open Access Journals (Sweden)

    Srinagesh V Koushik

    Full Text Available BACKGROUND: Förster resonance energy transfer (FRET is a mechanism where energy is transferred from an excited donor fluorophore to adjacent chromophores via non-radiative dipole-dipole interactions. FRET theory primarily considers the interactions of a single donor-acceptor pair. Unfortunately, it is rarely known if only a single acceptor is present in a molecular complex. Thus, the use of FRET as a tool for measuring protein-protein interactions inside living cells requires an understanding of how FRET changes with multiple acceptors. When multiple FRET acceptors are present it is assumed that a quantum of energy is either released from the donor, or transferred in toto to only one of the acceptors present. The rate of energy transfer between the donor and a specific acceptor (k(D-->A can be measured in the absence of other acceptors, and these individual FRET transfer rates can be used to predict the ensemble FRET efficiency using a simple kinetic model where the sum of all FRET transfer rates is divided by the sum of all radiative and non-radiative transfer rates. METHODOLOGY/PRINCIPAL FINDINGS: The generality of this approach was tested by measuring the ensemble FRET efficiency in two constructs, each containing a single fluorescent-protein donor (Cerulean and either two or three FRET acceptors (Venus. FRET transfer rates between individual donor-acceptor pairs within these constructs were calculated from FRET efficiencies measured after systematically introducing point mutations to eliminate all other acceptors. We find that the amount of energy transfer observed in constructs having multiple acceptors is significantly greater than the FRET efficiency predicted from the sum of the individual donor to acceptor transfer rates. CONCLUSIONS/SIGNIFICANCE: We conclude that either an additional energy transfer pathway exists when multiple acceptors are present, or that a theoretical assumption on which the kinetic model prediction is based is

  3. A new methodology for predictive tool wear

    Science.gov (United States)

    Kim, Won-Sik

    An empirical approach to tool wear, which requires a series of machining tests for each combination of insert and work material, has been a standard practice for industries since early part of the twentieth century. With many varieties of inserts and work materials available for machining, the empirical approach is too experiment-intensive that the demand for the development of a model-based approach is increasing. With a model-based approach, the developed wear equation can be extended without additional machining experiments. The main idea is that the temperatures on the primary wear areas are increasing such that the physical properties of the tool material degrade substantially and consequently tool wear increases. Dissolution and abrasion are identified to be the main mechanisms for tool wear. Flank wear is predominantly a phenomenon of abrasion as evident by the presence of a scoring mark on the flank surface. Based on this statement, it is reasonable to expect that the flank-wear rate would increase with the content of hard inclusions. However, experimental flank wear results did not necessary correspond to the content of cementite phase present in the steels. Hence, other phenomena are believed to significantly affect wear behavior under certain conditions. When the cutting temperature in the flank interface is subjected to high enough temperatures, pearlitic structure austenizes. During the formation of a new austenitic phase, the existing carbon is dissolved into the ferrite matrix, which will reduce the abrasive action. To verify the austenitic transformation, turning tests were conducted with plain carbon steels. The machined surface areas are imaged using X-ray diffraction the Scanning Electron Microscope (SEM) and the Transmission Electron Microscope (TEM). On the other hand, crater wear occurs as a result of dissolution wear and abrasive wear. To verify the wear mechanisms of crater wear, various coating inserts as well as uncoated inserts were

  4. 盘式制动器热应力磨损耦合行为的数值模拟%Numerical Simulation on the Coupling Behavior Between Thermal Load, Contact Stress and Wear in a Disc Brake

    Institute of Scientific and Technical Information of China (English)

    张方宇; 桂良进; 范子杰

    2014-01-01

    本文中探讨了盘式制动器制动过程中摩擦片和制动盘之间的热负荷接触应力磨损耦合行为的数值模拟方法。首先建立了盘式制动器的有限元模型;然后研究了应力磨损耦合分析的数值计算方法,并且模拟了摩擦片和制动盘的磨合过程;最后分别对热应力耦合条件下和紧急制动工况下的摩擦片磨损行为进行了模拟。结果表明,所提出的模拟方法是有效的。%The numerical simulation method of thermal load,contact stress and wear coupling behavior be-tween the pad and disk of disk brake during braking process is investigated in this paper. Firstly the finite element model for disk brake is built. Then the numerical calculation method of stress-wear coupling analysis is studied and the running-in process between pad and disk is simulated. Finally the wear behavior of brake pad in both stress-wear coupling and emergency braking conditions are simulated respectively. The results show that the simulation method proposed is effective.

  5. An investigation of abrasive wear and corrosion behavior of surface repair of gray cast iron by SMAW

    Directory of Open Access Journals (Sweden)

    Alireza Sadeghi

    2017-01-01

    Full Text Available In this work, improving the abrasion–corrosion behavior of gray cast iron used in centrifugal pumps was studied. These pumps are usually made of gray cast iron (BS:1452Gr220 and are repaired by Shielded Metal Arc Welding (SMAW. Three different typical welding electrodes including Ni electrode (DIN8563, Carbon Steel electrode (DIN1913, and Hardening electrode (DIN8555 were used to compare the weldability of the base metal. Microstructural differences for three types of electrodes were studied and forming of different phases was analyzed. Corrosion and abrasion tests were conducted and related to welding conditions. Experimental results showed that using Ni substrate electrode reduce the unwanted phases (martensitic and carbides. Furthermore, in comparison with the base metal, the abrasion behavior of all weldments was improved. It was also determined that the carbon steel electrode has a higher corrosion resistance in zero-resistance ammeter (ZRA test compared to other electrodes.

  6. Wear Behavior of Cold Pressed and Sintered Al2O3/TiC/CaF2Al2O3/TiC Laminated Ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    Xuefeng YANG; Jian CHENG; Peilong SONG; Shouren WANG; Liying YANG; Yanjun WANG; Ken MAO

    2013-01-01

    A novel laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite was fabricated through cold pressing and sintering to achieve better anti-wear performance,such as low friction coefficient and low wear rate.Al2O3/TiC/CaF2 and Al2O3/TiC composites were alternatively built layer-by-layer to obtain a sandwich structure.Solid lubricant CaF2 was added evenly into the Al2O3/TiC/CaF2 layer to reduce the friction and wear.Al2O3/TiC ceramic was also cold pressed and sintered for comparison.Friction analysis of the two ceramics was then conducted via a wear-and-tear machine.Worn surface and surface compositions were examined by scanning electron microscopy and energy dispersion spectrum,respectively.Results showed that the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite has lower friction coefficient and lower wear rate than those of Al2O3/TiC ceramic alone because of the addition of CaF2 into the laminated Al2O3/TiC/CaF2-Al2O3/TiC sandwich ceramic composite.Under the friction load,the tiny CaF2 particles were scraped from the Al2O3/TiC/CaF2 layer and spread on friction pairs before falling off into micropits.This process formed a smooth,self-lubricating film,which led to better anti-wear properties.Adhesive wear is the main wear mechanism of Al2O3/TiC/CaF2 layer and abrasive wear is the main wear mechanism of Al2O3/TiC layer.

  7. FRET and Non-FRET processes in quantum dot - dye nanoassemblies

    Energy Technology Data Exchange (ETDEWEB)

    Kowerko, Danny; Schuster, Joerg; Borczyskowski, Christian von [Center of Nanostructured Materials and Analytics, TU-Chemnitz, 09107 Chemnitz (Germany)

    2009-07-01

    Assemblies of semiconductor quantum dots (QDs - donor) and organic (dye - acceptor) molecules are of increasing interest for numerous applications in science and technology. Recent publications on such systems report on charge and fluorescence resonant energy transfer (FRET), prevalently neglecting an exact quantitative spectroscopic analysis of the acceptor. Recently, calculations of Seifert et al. and Blaudeck and coworkers demonstrated the crucial dependence of trap state emission from the surface coverage. In our contribution we emphasize the role of dye induces surface trap states as one mechanism - besides FRET - for QD quenching. Thus detailed quantitative analysis of titration experiments of differently functionalized perylenebismide molecules and CdSe/ZnS quantum dots will be discussed. By means of single particle spectroscopy we may even compare spectroscopic properties of the free and bound species on one and the same sample under identical conditions. Furthermore, analysis of FRET allows for a distinction between different geometries of the dye-QD assemblies.

  8. Nanostructured Al/SiC-Graphite Composites Produced by Accumulative Roll Bonding: Role of Graphite on Microstructure, Wear and Tensile Behavior

    Science.gov (United States)

    Reihanian, M.; Fayezipour, S.; Lari Baghal, S. M.

    2017-03-01

    Nanostructured Al/SiC composite was fabricated by accumulative roll bonding (ARB). The effect of Gr, as the soft and second reinforcing particle, on the microstructure and deformation behavior of Al/SiC composite was examined. After eight ARB cycles, a homogeneous ultra-fine grained structure with the average grain size of about 710 nm was obtained in the Al/SiC composite. Results showed that Gr could not affect the particle distribution. However, the bonding quality between the layers reduced and the mechanical properties of the composite deteriorated considerably with increasing the Gr content. Compared with the Gr-free composite, the Al/SiC-Gr hybrid composite with the highest Gr content exhibited the lowest bonding quality and the lowest tensile strength. Tensile fracture surface of the composites showed that the number of delaminated layers was increased by increasing the Gr content. The best wear resistance was obtained in the composite whose powder mixture contained 80 SiC and 20 Gr (in wt.%).

  9. Discrimination between FRET and non-FRET quenching in a photochromic CdSe quantum dot/dithienylethene dye system

    Science.gov (United States)

    Dworak, Lars; Reuss, Andreas J.; Zastrow, Marc; Rück-Braun, Karola; Wachtveitl, Josef

    2014-11-01

    A photochromic Förster resonance energy transfer (FRET) system was employed to disentangle the fluorescence quenching mechanisms in quantum dot/photochromic dye hybrids. In the off-state of the dye the main quenching mechanism is FRET whereas the moderate quenching in the on-state is due to non-FRET pathways opened up upon assembly.A photochromic Förster resonance energy transfer (FRET) system was employed to disentangle the fluorescence quenching mechanisms in quantum dot/photochromic dye hybrids. In the off-state of the dye the main quenching mechanism is FRET whereas the moderate quenching in the on-state is due to non-FRET pathways opened up upon assembly. Electronic supplementary information (ESI) available: QD and DTE synthesis, preparation of the DTE/QD coupled system, TEM image of the nanocrystals and experimental details. See DOI: 10.1039/c4nr05144k

  10. Wearing gloves in the hospital

    Science.gov (United States)

    ... gloves; PPE - wearing gloves; Nosocomial infection - wearing gloves; Hospital acquired infection - wearing gloves ... Wearing gloves in the hospital helps prevent the spread of germs. This helps protect both patients and health care workers from infection.

  11. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.

    1996-01-01

    Pin-on-disc tests of tungsten carbide pins against silicon carbide discs were performed and wear rate, mechanism and friction maps constructed. Correlations were observed between the wear mode and the friction of the pin-disc interface, and between the qualitative incidence of disruptive wear...

  12. Wear Debris Analysis:Fundamental Principle of Wear-Graphy

    Institute of Scientific and Technical Information of China (English)

    陈铭; 王伟华; 殷勇辉; 王成焘

    2004-01-01

    A new wear-graphy technology was developed, which can simultaneously identify the shape and composition of wear debris, for both metals and non-metals.The fundamental principles of the wear-graphy system and its wear-gram system are discussed here.A method was developed to distribute wear debris on a slide uniformly to reduce overlapping of wear debris while smearing.The composition identification analyzes the wear debris using the scanning electron microscope (SEM) energy spectrum, infrared-thermal imaging and X-ray imaging technology.A wear debris analysis system based on database techniques is demonstrated, and a visible digitized wear-gram is acquired based on the information of wear debris with image collection and processing of the wear debris.The method gives the morphological characteristics of the wear debris, material composition identification of the wear debris, intelligent recognition of the wear debris, and storage and management of wear debris information.

  13. Modeling wear of cast Ti alloys.

    Science.gov (United States)

    Chan, Kwai S; Koike, Marie; Okabe, Toru

    2007-05-01

    The wear behavior of Ti-based alloys was analyzed by considering the elastic-plastic fracture of individual alloys in response to the relevant contact stress field. Using the contact stresses as the process driving force, wear was computed as the wear rate or volume loss as a function of hardness and tensile ductility for Ti-based cast alloys containing an alpha, alpha+beta or beta microstructure with or without the intermetallic precipitates. Model predictions indicated that wear of Ti alloys increases with increasing hardness but with decreasing fracture toughness or tensile ductility. The theoretical results are compared with experimental data to elucidate the roles of microstructure in wear and contrasted against those in grindability.

  14. Single molecule FRET data analysis procedures for FRET efficiency determination: probing the conformations of nucleic acid structures.

    Science.gov (United States)

    Krüger, Asger Christian; Birkedal, Victoria

    2013-11-01

    Single molecule FRET microscopy is an attractive technique for studying structural dynamics and conformational diversity of nucleic acid structures. Some of its strengths are that it can follow structural changes on a fast time scale and identify conformation distributions arising from dynamic or static population heterogeneity. Here, we give a description of the experiment and data analysis procedures of this method and detail what parameters are needed for FRET efficiency calculation. Using single molecule FRET data obtained on G-quadruplex DNA structures that exhibit large conformation diversity, we illustrate that the shape of the FRET distribution changes depending on what parameters are included in the data analysis procedure.

  15. Interactions between nonlinear spur gear dynamics and surface wear

    Science.gov (United States)

    Ding, Huali; Kahraman, Ahmet

    2007-11-01

    In this study, two different dynamic models, a finite elements-based deformable-body model and a simplified discrete model, and a surface wear model are combined to study the interaction between gear surface wear and gear dynamic response. The proposed dynamic gear wear model includes the influence of worn surface profiles on dynamic tooth forces and transmission error as well as the influence of dynamic tooth forces on wear profiles. This paper first introduces the nonlinear dynamic models that include gear backlash and time-varying gear mesh stiffness, and a wear model separately. It presents a comparison to experiments for validation of the dynamic models. The dynamic models are combined with the wear model to study the interaction of surface wear and dynamic behavior in both linear and nonlinear response regimes. At the end, several sets of simulation results are used to demonstrate the two-way relationship between nonlinear gear dynamics and surface wear.

  16. In silico FRET from simulated dye dynamics

    Science.gov (United States)

    Hoefling, Martin; Grubmüller, Helmut

    2013-03-01

    Single molecule fluorescence resonance energy transfer (smFRET) experiments probe molecular distances on the nanometer scale. In such experiments, distances are recorded from FRET transfer efficiencies via the Förster formula, E=1/(1+(). The energy transfer however also depends on the mutual orientation of the two dyes used as distance reporter. Since this information is typically inaccessible in FRET experiments, one has to rely on approximations, which reduce the accuracy of these distance measurements. A common approximation is an isotropic and uncorrelated dye orientation distribution. To assess the impact of such approximations, we present the algorithms and implementation of a computational toolkit for the simulation of smFRET on the basis of molecular dynamics (MD) trajectory ensembles. In this study, the dye orientation dynamics, which are used to determine dynamic FRET efficiencies, are extracted from MD simulations. In a subsequent step, photons and bursts are generated using a Monte Carlo algorithm. The application of the developed toolkit on a poly-proline system demonstrated good agreement between smFRET simulations and experimental results and therefore confirms our computational method. Furthermore, it enabled the identification of the structural basis of measured heterogeneity. The presented computational toolkit is written in Python, available as open-source, applicable to arbitrary systems and can easily be extended and adapted to further problems. Catalogue identifier: AENV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GPLv3, the bundled SIMD friendly Mersenne twister implementation [1] is provided under the SFMT-License. No. of lines in distributed program, including test data, etc.: 317880 No. of bytes in distributed program, including test data, etc.: 54774217 Distribution format: tar.gz Programming language

  17. Effects of heat treatment on wear behavior of carbon/carbon-copper composites under electrical current%热处理对炭/炭-铜复合材料载流磨损行为的影响

    Institute of Scientific and Technical Information of China (English)

    杨鹏翱; 张红波; 尹健; 杨双磊

    2015-01-01

    To explore the effects of heat treatment of Carbon/Carbon ( C/C ) substrates on wear behavior of Carbon/Carbon⁃Copper ( C/C-Cu) composites, copper⁃impregnated carbon fiber reinforced carbon composites were fabricated by infiltrating molten copper alloy into C/C substrates, which were made by chemical vapor infiltration ( CVI) . The wear behavior of C/C-Cu composites was investigated by using a dynamic wear test apparatus during application of an AC electrical current. The worn surfaces of composites before and after test were observed by 3D microscope and SEM. Effects of 2 000℃ heat treatment of C/C substrates on wear behavior of C/C-Cu composites were investigated. The results indicate that the mass wear rate and linear wear rate of the C/C-Cu composites whose C/C substrates were treated at 2 000 ℃ were 34. 42% and 17. 84%, respectively, lower than that of composites without heat treatment. The graphitization degree of C/C substrates improved after 2 000 ℃ heat treatment, thus, the interlaminar splitting resistance was reduced. Thus it is easier for graphite sheets to split into small graphite scraps and form a smooth and lubricant film on the surface, which restrained the inhomogeneous wear induced by surface defects. Therefore, the mutual effects of abrasive wear, adhesive wear, oxidation wear and arc ablation are weakened.%为探明炭/炭( C/C)多孔体热处理对炭/炭-铜( C/C-Cu)复合材料载流磨损行为的影响,采用化学气相渗透法( CVI)增密的C/C多孔体,再通过压力熔渗法制备C/C-Cu复合材料.采用载流动态磨损试验机测试C/C-Cu复合材料载流磨损行为,利用数字式三维视频显微镜和扫描电子显微镜观察复合材料磨损前后的表面形貌,研究了C/C多孔体经过2000℃热处理对C/C-Cu复合材料载流磨损行为的影响.结果表明:C/C-Cu复合材料的质量磨损率和线磨损率比C/C多孔体未经热处理

  18. Microstructure and wear behavior of γ/Al 4C 3/TiC/CaF 2 composite coating on γ-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

    Science.gov (United States)

    Liu, Xiu-Bo; Shi, Shi-Hong; Guo, Jian; Fu, Ge-Yan; Wang, Ming-Di

    2009-03-01

    As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF 2 in the preparation of precursor NiCr-Cr 3C 2-CaF 2 mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al 4C 3 carbides reinforcement as well as fine isolated spherical CaF 2 solid lubrication particles uniformly dispersed in the NiCrAlTi ( γ) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF 2 and the increasing of it's wettability with the NiCrAlTi ( γ) matrix during the laser cladding process.

  19. 45号钢微动疲劳门坎值特性研究%Research on 45-carbon steel fretting fatigue damage threshold properties

    Institute of Scientific and Technical Information of China (English)

    邢海军; 赵颖娣; 俞新宇; 苏彬; 孙伟明

    2011-01-01

    The fretting fatigue damage threshold studies were conducted on 45-carbon steel through interrupted fretting fatigue tests, and the relationship between the contact surface crack characteristics and the number of fretting wear cycles was also investigated. There exists a fretting fatigue damage threshold on 45-carbon steel, when the number of fretting wear cycles is over the threshold value cycles, the fatigue life of the specimen will be decreased significantly. The damage levels were calculated as a percentage of the total cycles with fretting for 100% of its life to fracture for the baseline fretting fatigue specimen. The value of the threshold is in the range of 20%~40%. The threshold value remains the unchanged with changing the conditions of the load on specimens. Microscopic observation shows that there were obvious long cracks on the contact surface when the fretting cycles were more than the threshold value.%通过中断性试验研究了45号钢的微动疲劳门坎值,并对不同微动次数下接触面的裂纹特征进行了观察.试验测得45号钢显著存在一个微动疲劳门坎值,微动次数直至超过微动疲劳门坎值时,微动才会使试样疲劳寿命显著下降.以试样上预定的微动循环次数与全微动下试样疲劳基准寿命的比值表示,其微动疲劳门坎值大约在20%~40%范围内.改变载荷条件,该门坎值仍保持在20%~40%范围内;显微观察显示,在微动循环次数超过门坎值之后,在接触磨损面上几乎都能观察到明显的大裂纹.

  20. Effects of tool geometry and welding rates on the tool wear behavior and shape optimization in friction stir welding of aluminum alloy 6061 + 20% aluminum oxide MMC

    Science.gov (United States)

    Prado, Rafael Arcangel

    FSW is a new solid-state process currently being investigated for joining aluminum alloys that are difficult to weld, where there is no perceptible wear of the pin tool throughout the experiment. The present report investigates and examines tool wear in the friction-stir welding of Al 6061-T6 and Al 6061-T6 containing 20% (volume) Al2O3 particles, a metal matrix composite (MMC), in order to compare wear optimized tool geometries and corresponding parameters. The weld tool, referred to as pin tool or nib, did not exhibit any measurable wear in the FSW of the 6061 Al alloy even after traversing tens of meters of material. However, the pin tool geometry changed during the FSW of the Al 6061-T6 containing 20% (volume) Al2O3 particles. Tool wear was measured in relation to the original tool by weighing the photograph of the tool and comparing the percentage change relative to the original tool photograph. The maximum wear rate was roughly 0.64 %/cm at 1000 rpm for the MMC at 1 mm/s traverse speed. The best performance involving the least wear for MMC FSW was observed at a tool rotational speed of 500 rpm and a traverse speed of 3 mm/s; where the corresponding wear rate was 0.13 %/cm. Optical, scanning and transmission microscopy were used to characterize the microstructures of the base material and weld zone for the MMC confirming the solid phase nature of the technique. The microstructure of the friction stir weld zone shows a characteristic dynamic recrystallization phenomenon that acts as a mechanism to accommodate the super-plastic deformation and facilitates the bonding. Rockwell E hardness profiles for both aluminum alloys were measured from the base metals through the FSW zone near the through-thickness mid-section. In the FSW of Al 6061 containing 20% (volume) Al2O3 particles, tool wear has been shown to depend primarily on rotational and traverse speeds, with optimum wear occurring at 1000 rpm. However, as the traverse or actual weld speed is increased from 1

  1. Fabrication and Wear Behavior Analysis on AlCrFeNi High Entropy Alloy Coating Under Dry Sliding and Oil Lubrication Test Conditions

    Science.gov (United States)

    Tang, Yipin; Wang, Shouren; Sun, Bin; Wang, Yan; Qiao, Yang

    2016-03-01

    In this paper, AlCrFeNi high entropy alloy coating was fabricated on the surface of Q235 steel using hot pressing sintering process. The coating has the controlled thickness size and excellent mechanical properties. Scanning electron microscopy (SEM), XRD and hardness testing method were used to study the morphology, phase structure and hardness of high entropy alloys coating. The lattice distortion plays a significant role in increasing the hardness. Coating formation mechanism caused by the element diffusion under the hot pressing effect is also discussed in the paper. Simultaneously, the dry sliding and oil lubrication wear tests, wear morphology observation and wear mechanism discussion were completed. As the result shows, AlCrFeNi high entropy alloys coating exhibits superior wear resistance either at dry sliding or oil lubrication tests owing to its hard high entropy solid solution structure.

  2. 女性自我概念与女装消费行为实证研究*%Empirical Study on Women’s Self-concept and Women’s Wear Consumer Behavior

    Institute of Scientific and Technical Information of China (English)

    钟敏维

    2013-01-01

    Women’s self-concept was applied to women’s wear consumer behavior. Empirical study method was used by designing scales for women’s self-concept and women’s wear consumer behavior. The different factors of women’s self-concept were obtained by using factor analysis method. Besides, correlation analysis was applied to reveal the relationship between self-concept and women’s wear consumer behavior.%  本文把女性自我概念结构应用于女装消费行为研究,采用实证研究方法,设计女性自我概念与女装消费行为量表,并对有效样本进行因子分析和相关分析,验证了女性自我概念与女装消费行为之间的关系,揭示了女性服装消费行为的特征。

  3. Fret Replica Inspection Laser Scanner (FRILS)

    Energy Technology Data Exchange (ETDEWEB)

    Kretz, S.; Hanley, K., E-mail: steve.kretz@opg.com, E-mail: kelly.hanley@opg.com [Ontario Power Generation, Inspection Maintenance and Commercial Services, Pickering, Ontario (Canada)

    2008-07-01

    In the stress analysis of flaws and artifacts found in pressure tubes, it is crucial to have detailed knowledge of the flaw geometry. Fuel channel inspections by ultrasonic or eddy current inspection methods alone cannot provide the complete required geometry information. Replicas, which are a negative impression of surface pressure tube indications, are scanned with a laser system which will provide the additional detail required. FRILS was initially developed in 1993 to establish in-house capability of profiling indications on the inside diameter surface of pressure tubes. The need of this profiling was initially a response to the discovery of fuel bundle bearing pad fretting (FBBPF) caused by flow induced fuel bundle vibration. The benefits of the system were soon realized as a tool for profiling debris type indications. Although the primary use of FRILS is to profile FBBBF and Debris Fretting, since its inception the FRILS inspection system has become an instrumental tool in flaw assessment for: Fuel Bundle Bearing Pad Frets (FBBPF); Debris Frets; Scratches; Crevice Corrosion; Oxide Jacking; Areas of surface roughness; and, Weld Profiling. Replicas are collected via acquisition from tooling on both the Channel and Gauging Apparatus for Reactors (CIGAR) and the Advanced Non-Destructive Examination (ANDE) systems. The ANDE system is a high speed data acquisition system which includes both an ultrasonic inspection tool and a replication tool. Although both of these tools were designed to be delivered with the UDM, the platform for these tools was built with flexibility allowing for adoption to other delivery systems. These tools were based on the experience of the CIGAR inspection system. The CIGAR system has also undergone many system upgrades resulting in reduced inspection times. The FRILS system - Fret Replication Inspection Laser Scanner system was developed and has been upgraded to meet the demands of the improved inspection and replication systems. FRILS

  4. BOBA FRET: bootstrap-based analysis of single-molecule FRET data.

    Directory of Open Access Journals (Sweden)

    Sebastian L B König

    Full Text Available Time-binned single-molecule Förster resonance energy transfer (smFRET experiments with surface-tethered nucleic acids or proteins permit to follow folding and catalysis of single molecules in real-time. Due to the intrinsically low signal-to-noise ratio (SNR in smFRET time traces, research over the past years has focused on the development of new methods to extract discrete states (conformations from noisy data. However, limited observation time typically leads to pronounced cross-sample variability, i.e., single molecules display differences in the relative population of states and the corresponding conversion rates. Quantification of cross-sample variability is necessary to perform statistical testing in order to assess whether changes observed in response to an experimental parameter (metal ion concentration, the presence of a ligand, etc. are significant. However, such hypothesis testing has been disregarded to date, precluding robust biological interpretation. Here, we address this problem by a bootstrap-based approach to estimate the experimental variability. Simulated time traces are presented to assess the robustness of the algorithm in conjunction with approaches commonly used in thermodynamic and kinetic analysis of time-binned smFRET data. Furthermore, a pair of functionally important sequences derived from the self-cleaving group II intron Sc.ai5γ (d3'EBS1/IBS1 is used as a model system. Through statistical hypothesis testing, divalent metal ions are shown to have a statistically significant effect on both thermodynamic and kinetic aspects of their interaction. The Matlab source code used for analysis (bootstrap-based analysis of smFRET data, BOBA FRET, as well as a graphical user interface, is available via http://www.aci.uzh.ch/rna/.

  5. Large Scale Bacterial Colony Screening of Diversified FRET Biosensors.

    Directory of Open Access Journals (Sweden)

    Julia Litzlbauer

    Full Text Available Biosensors based on Förster Resonance Energy Transfer (FRET between fluorescent protein mutants have started to revolutionize physiology and biochemistry. However, many types of FRET biosensors show relatively small FRET changes, making measurements with these probes challenging when used under sub-optimal experimental conditions. Thus, a major effort in the field currently lies in designing new optimization strategies for these types of sensors. Here we describe procedures for optimizing FRET changes by large scale screening of mutant biosensor libraries in bacterial colonies. We describe optimization of biosensor expression, permeabilization of bacteria, software tools for analysis, and screening conditions. The procedures reported here may help in improving FRET changes in multiple suitable classes of biosensors.

  6. Ice and debris in the fretted terrain, Mars

    Science.gov (United States)

    Lucchitta, B. K.

    1984-01-01

    Viking moderate and high resolution images along the northern highland margin have been monoscopically and stereoscopically examined in order to study the development of fretted terrain. Young debris aprons around mesas and debris in tributary channels create typical fretted morphologies identical to ancient fretted morphologies. This suggests that the debris-apron process operating relatively recently also shaped the fretted terrain of the past. The debris aprons were lubricated by interstitial ice derived from ground ice. Abundant collapse features suggest that ground ice existed and may have flowed in places. The fretting process has been active for a long period and may be active today. The location of debris aprons in two latitudinal belts may be controlled by atmospheric conditions that permit ice in the region to remain in the ground below depths of about one meter and temperatures warm enough for ice to flow.

  7. Near surface stress analysis strategies for axisymmetric fretting

    Indian Academy of Sciences (India)

    M Ramesh; Satish V Kailas; K R Y Simha

    2008-06-01

    Fretting is essentially a surface phenomenon, but bulk stresses and material properties contribute to subsequent failure. This feature of fretting demands a thorough understanding of near surface stresses under the joint action of normal, shear and thermal loading. Axisymmetric fretting is of great concern in piping and coupling design. In this paper, we develop design tools for Near Surface Analysis (NSA) for understanding axisymmetric fretting. Axisymmetric Fretting Analysis (AFA) becomes formidable owing to localised tractions that call for Fourier transform techniques. We develop two different NSA strategies based on two-dimensional plane strain models: 2D strip model (2DS) and half-plane Flamant model (2DF). We compare the results of 2DS and 2DF with the exact results for AFA obtained using Love’s stress function in conjunction with Fourier transform. There is a good correspondence between stress components obtained from 2D-models.

  8. Effects of Varying Epoch Lengths, Wear Time Algorithms, and Activity Cut-Points on Estimates of Child Sedentary Behavior and Physical Activity from Accelerometer Data.

    Directory of Open Access Journals (Sweden)

    Jorge A Banda

    Full Text Available To examine the effects of accelerometer epoch lengths, wear time (WT algorithms, and activity cut-points on estimates of WT, sedentary behavior (SB, and physical activity (PA.268 7-11 year-olds with BMI ≥ 85th percentile for age and sex wore accelerometers on their right hips for 4-7 days. Data were processed and analyzed at epoch lengths of 1-, 5-, 10-, 15-, 30-, and 60-seconds. For each epoch length, WT minutes/day was determined using three common WT algorithms, and minutes/day and percent time spent in SB, light (LPA, moderate (MPA, and vigorous (VPA PA were determined using five common activity cut-points. ANOVA tested differences in WT, SB, LPA, MPA, VPA, and MVPA when using the different epoch lengths, WT algorithms, and activity cut-points.WT minutes/day varied significantly by epoch length when using the NHANES WT algorithm (p < .0001, but did not vary significantly by epoch length when using the ≥ 20 minute consecutive zero or Choi WT algorithms. Minutes/day and percent time spent in SB, LPA, MPA, VPA, and MVPA varied significantly by epoch length for all sets of activity cut-points tested with all three WT algorithms (all p < .0001. Across all epoch lengths, minutes/day and percent time spent in SB, LPA, MPA, VPA, and MVPA also varied significantly across all sets of activity cut-points with all three WT algorithms (all p < .0001.The common practice of converting WT algorithms and activity cut-point definitions to match different epoch lengths may introduce significant errors. Estimates of SB and PA from studies that process and analyze data using different epoch lengths, WT algorithms, and/or activity cut-points are not comparable, potentially leading to very different results, interpretations, and conclusions, misleading research and public policy.

  9. ETP-0474: Evaluation of Electroless Nickel Coatings to Achieve Interference Fit in the RSRM Without Fretting

    Science.gov (United States)

    Schaffnit, William O.

    1997-01-01

    Part of the redesign of the SRMs for the Space Shuttle involved the substitution of three new capture cylinders for three of the previously used cylinders. These new cylinders mate with the old standard case segments in each of the three field joints. The new capture cylinders contain an integral capture latch on the tang end which mates with a case clevis during stackup at KSC. The capture cylinders also contain a groove in the capture latch to provide for a third 0-ring in the joint and are designed to achieve a metal-to- metal interference fit between the capture latch and the mating clevis. An unexpected fretting problem has occurred on the tang capture feature and the inner clevis leg interference fit surfaces on flight hardware since STS-26. Varying degrees of fretting damage have been found on the case segments from different flight motors. Fretting is a wear phenomena that occurs when two tightly fitting metal surfaces are subject to cyclic relative motion of extremely small amplitudes (generally less than 0.010-inch) in the absence of adequate lubrication. It is adhesive ("cold" - welding) in nature and vibration is its essential causative factor. This problem has manifested itself on the flight motors as a series of pits and axial gouges on the inside diameter (ID) surfaces of the inner clevis legs and the outside diameter (OD) surfaces of the tang capture features. The problem occurs in varying degrees of severity in all of the field joints. It is not believed that fretting is a flight safety issue. However, it could become a reusability issue if left unattended. Fretting has been encountered in other industries for many years and measures that will prevent or reduce it have been devised. These include: elimination or reduction of vibration (amplitudes and/or frequencies), elimination of slip, improved lubrication between parts, increased surface separation, increased interference, inducing residual compressive stresses in the surfaces of the mating

  10. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup......Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  11. Polymer wear evaluation

    DEFF Research Database (Denmark)

    Lagerbon, Mikkel; Sivebæk, Ion Marius

    2012-01-01

    Polymer wear plays an increasing role in manufacturing of machine parts for e.g. medical devices. Some of these have an expected lifetime of five to eight years during which very little wear of the components is acceptable. Too much wear compromises the dosage accuracy of the device and thereby...... the safety of the patients. Prediction of the wear of polymers is complicated by the low thermal conductivity of this kind of material. It implies that any acceleration of testing conditions by increased contact pressure and/or sliding velocity will make the polymer fail due to exaggerated heat buildup....... This is not the kind of wear observed in medical devices. In the present work a method was developed capable of evaluating the wear progression in polymer-polymer contacts. The configuration of the setup is injection moulded specimens consisting of an upper part having a toroid shape and a lower flat part. The sliding...

  12. Wear of connector contacts exposed to relative motion

    Science.gov (United States)

    Wilk, R. A.

    Connectors play a significant role in the performance, cost, and reliability of electronic equipment. In connection with the development of the system interconnection design, a factor which is often overlooked is related to the importance of connector selection and mounting to minimize relative motion between contacts during vibration encountered in handling, transportation, and service. This motion can lead to the loss of protective coatings (gold and nickel) due to frictional wear. If this happens, fretting corrosion of the base metals may occur. The produced damage can adversely affect performance due to increased joint resistance, eventually causing intermittent contacts. The present investigation is concerned with the study of different style contacts (tuning fork, box, and circular) to determine their endurance and wear characteristics when exposed to relative motion created by vibration. All contacts investigated were fabricated from brass, beryllium copper, or phosphor bronze, and had .00127 mm minimum gold plating over .00127 mm minimum nickel plating.

  13. Microstructure and Dry Sliding Wear Behavior of Fe-Based (Cr, Fe)7C3 Composite Coating Fabricated by PTA Welding Process

    Science.gov (United States)

    Yuan, Y. L.; Li, Z. G.

    2013-11-01

    Using Cr3C2 and Fe-CrNiBSi powder blends as raw materials, an α-Fe matrix composite coating reinforced by in situ (Cr, Fe)7C3 rods, with a thickness of about 3.6 mm, was fabricated on the surface of AISI A36 low carbon steel by means of plasma-transferred arc welding. The results of microstructural analysis show that in the coating, a large number of carbides, (Cr, Fe)7C3, in rod shape grow, and radiate around some half-dissolved Cr3C2 particles. The results of dry sliding wear tests at loads 100, 200, and 300 N show that the wear resistances of (Cr, Fe)7C3-reinforced coating, respectively, are about 6.9, 14.9, and 17 times higher than that of nonreinforced pure Fe-CrNiBSi alloy coating; the average value and fluctuation range of friction coefficient (FC) of (Cr, Fe)7C3-reinforced coating are less than those of pure Fe-CrNiBSi alloy coating; the main wear mechanisms of pure Fe-CrNiBSi alloy coating are ploughing, deformation, and adhesive wear, whereas those of (Cr, Fe)7C3-reinforced coating are microcutting, abrasive, and oxidation wear; the cracks on surfaces of (Cr, Fe)7C3 rods increased with the increasing loads; and the matrix α-Fe can prevent them from extending further in the composite coating.

  14. Wear behavior of wet clutches

    OpenAIRE

    2012-01-01

    Human civilization is largely based on the transformation of stored chemical energy in the form of fossil fuels into usable work through the use of the combustion engine. In recent years, the awareness of problems such as global warming due to emissions of greenhouse gases and the depletion of fossil fuel reserves has increased. New regulations have been put into place in order to limit these effects and as a result, the efforts made by the automotive industry to limit the emissions and fuel ...

  15. An ion-insensitive cAMP biosensor for long term quantitative ratiometric fluorescence resonance energy transfer (FRET) measurements under variable physiological conditions.

    Science.gov (United States)

    Salonikidis, Petrus S; Niebert, Marcus; Ullrich, Tim; Bao, Guobin; Zeug, Andre; Richter, Diethelm W

    2011-07-01

    Ratiometric measurements with FRET-based biosensors in living cells using a single fluorescence excitation wavelength are often affected by a significant ion sensitivity and the aggregation behavior of the FRET pair. This is an important problem for quantitative approaches. Here we report on the influence of physiological ion concentration changes on quantitative ratiometric measurements by comparing different FRET pairs for a cAMP-detecting biosensor. We exchanged the enhanced CFP/enhanced YFP FRET pair of an established Epac1-based biosensor by the fluorophores mCerulean/mCitrine. In the case of enhanced CFP/enhanced YFP, we showed that changes in proton, and (to a lesser extent) chloride ion concentrations result in incorrect ratiometric FRET signals, which may exceed the dynamic range of the biosensor. Calcium ions have no direct, but an indirect pH-driven effect by mobilizing protons. These ion dependences were greatly eliminated when mCerulean/mCitrine fluorophores were used. For such advanced FRET pairs the biosensor is less sensitive to changes in ion concentration and allows consistent cAMP concentration measurements under different physiological conditions, as occur in metabolically active cells. In addition, we verified that the described FRET pair exchange increased the dynamic range of the FRET efficiency response. The time window for stable experimental conditions was also prolonged by a faster biosensor expression rate in transfected cells and a greatly reduced tendency to aggregate, which reduces cytotoxicity. These properties were verified in functional tests in single cells co-expressing the biosensor and the 5-HT(1A) receptor.

  16. Single-molecule FRET reveals the native-state dynamics of the IκBα ankyrin repeat domain.

    Science.gov (United States)

    Lamboy, Jorge A; Kim, Hajin; Dembinski, Holly; Ha, Taekjip; Komives, Elizabeth A

    2013-07-24

    Previous single-molecule fluorescence resonance energy transfer (smFRET) studies in which the second and sixth ankyrin repeats (ARs) of IκBα were labeled with FRET pairs showed slow fluctuations as if the IκBα AR domain was unfolding in its native state. To systematically probe where these slow dynamic fluctuations occur, we now present data from smFRET studies wherein FRET labels were placed at ARs 1 and 4 (mutant named AR 1-4), at ARs 2 and 5 (AR 2-5), and at ARs 3 and 6 (AR 3-6). The results presented here reveal that AR 6 most readily detaches/unfolds from the AR domain, undergoing substantial fluctuations at room temperature. AR 6 has fewer stabilizing consensus residues than the other IκBα ARs, probably contributing to the ease with which AR 6 "loses grip". AR 5 shows almost no fluctuations at room temperature, but a significant fraction of molecules shows fluctuations at 37 °C. Introduction of stabilizing mutations that are known to fold AR 6 dampen the fluctuations of AR 5, indicating that the AR 5 fluctuations are likely due to weakened inter-repeat stabilization from AR 6. AR 1 also fluctuates somewhat at room temperature, suggesting that fluctuations are a general behavior of ARs at ends of AR domains. Remarkably, AR 1 still fluctuates in the bound state, but mainly between 0.6 and 0.9 FRET efficiency, whereas in the free IκBα, the fluctuations extend to <0.5 FRET efficiency. Overall, our results provide a more complete picture of the energy landscape of the native state dynamics of an AR domain.

  17. Understanding FRET as a Research Tool for Cellular Studies

    Directory of Open Access Journals (Sweden)

    Dilip Shrestha

    2015-03-01

    Full Text Available Communication of molecular species through dynamic association and/or dissociation at various cellular sites governs biological functions. Understanding these physiological processes require delineation of molecular events occurring at the level of individual complexes in a living cell. Among the few non-invasive approaches with nanometer resolution are methods based on Förster Resonance Energy Transfer (FRET. FRET is effective at a distance of 1–10 nm which is equivalent to the size of macromolecules, thus providing an unprecedented level of detail on molecular interactions. The emergence of fluorescent proteins and SNAP- and CLIP- tag proteins provided FRET with the capability to monitor changes in a molecular complex in real-time making it possible to establish the functional significance of the studied molecules in a native environment. Now, FRET is widely used in biological sciences, including the field of proteomics, signal transduction, diagnostics and drug development to address questions almost unimaginable with biochemical methods and conventional microscopies. However, the underlying physics of FRET often scares biologists. Therefore, in this review, our goal is to introduce FRET to non-physicists in a lucid manner. We will also discuss our contributions to various FRET methodologies based on microscopy and flow cytometry, while describing its application for determining the molecular heterogeneity of the plasma membrane in various cell types.

  18. Dynamic SEM wear studies of tungsten carbide cermets

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined. Etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the WC and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation. The wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  19. Numerical Simulation of Radial Fretting Behaviors on Wind Turbine Slewing Bearings%风电转盘轴承径向微动磨损的数值模拟

    Institute of Scientific and Technical Information of China (English)

    钱锴; 陈捷; 高学海; 王华

    2013-01-01

    以某1.5MW转盘轴承为研究对象,应用ABAQUS软件建立三维球(GCr15轴承钢)/滚道(42CrMo钢)接触弹塑性有限元模型,通过改变滚珠与滚道接触时的曲率比,实现球、滚道接触的径向磨损模式,研究了不同曲率比对滚珠与滚道之间接触应力、相对滑移量和动力学曲线等摩擦学关键参数的影响规律.研究结果表明:滚道的塑性变形主要发生在第一次加载卸载过程中,后续加载循环塑性变形并不明显;随着曲率比的增加,滚道的变形增大,磨损区域减少;模型的最大应力不在接触表面产生,出现在距离接触表面深度1mm处,这与实际损伤结果相符.%With a 1.5MW slewing bearing as the research object,it uses ABAQUS to built 3d ball (GCr15 bearing steel)/raceway (42CrMo steel) contact elastoplastic finite element model.By changing the curvature of the boll and raceway contact ratio,ball and raceway contact radial wear pattern,it studies the different curvature ratio between ball and raceway contact stress,and also the relative slippage and kinetics curve of tribology key parameters are studied.The simulation results are practically consistent with test results reported by somebody else.Plastic deformation mainly occurs in the first working cycle,and the subsequent cyclic is not obvious.Deformation of raceway was increased and wear area was reduced on contact zone with the increase of the ratio of curvature.The maximum stress was not appeared in contact surface,but it was appeared in the distance contact surface depth in 1mm.

  20. AA6061/ZrB2原位复合材料的干滑动磨损行为%Dry sliding wear behavior of AA6061/ZrB2 in-situ composite

    Institute of Scientific and Technical Information of China (English)

    I. DINAHARAN; N. MURUGAN

    2012-01-01

    The dry sliding wear behavior of AA6061/ZrB2 in-situ composite prepared by the reaction of inorganic salts K2ZrF6 and KBF4 with molten aluminum was investigated.An attempt was made to develop a mathematical model to predict the wear rate of AA6061/(0-10%) ZrB2 in-situ composites.Four-factor,five-level central composite rotatable design was used to minimize the number of experiments.The factors considered are sliding velocity,sliding distance,normal load and mass fraction of ZrB2 particles.The effect of these factors on the wear rate of the fabricated composite was analyzed and the predicted trends were discussed by observing the wear surface morphologies.The in-situ formed ZrB2 particles enhance the wear performance of the composite.The wear rate of the composite bears a proportional relationship with the sliding velocity,sliding distance and normal load.%通过往铝熔体中添加K2ZrF6和KBF4制备AA6061/ZrB2原位复合材料,并对该复合材料的干滑动磨损形为进行研究.构建了一数学模型来预测该复合材料的磨损速率.采用4因素5水平的中心复合旋转设计方法来减少实验工作量.考察滑动速度、滑动距离、载荷和ZrB2质量分数这4个因素对制备的复合材料的磨损速率的影响,通过观察磨损表面形貌分析这些因素的影响.结果表明,原位生成的ZrB2颗粒改善了复合材料的磨损性能.该复合材料的磨损速率随着滑动速度、滑动距离和载荷的增加而增加.

  1. Comparative Study of the Friction and Wear Behavior of Natura lTooth and Several Dental Prosthetic Materials%天然牙及几种牙科修复材料的摩擦磨损性能比较研究

    Institute of Scientific and Technical Information of China (English)

    黎红; 周仲荣; 张杰; 陈光雄

    2001-01-01

    The friction and wear behaviour of natural living tooth and several dental prosthetic materials made of polymer, metal, and ceram ics in sliding against SAE52100 steel was investigated on a modified fretting fr iction and wear test rig. The worn surface morphologies of the living tooth and several dental prosthetic materials were observed with an optical microscope and a scanning electron microscope. The results show that natural tooth records a l ow friction coefficient and a small wear scar depth in sliding against the steel ball. The specimens made from Bayer tooth, thermosetting plastic, copper-base alloy, titanium and its alloy have relatively good wear-resistance as well and are thus idea prosthetic materials. Especially, titanium and its alloy are prosp ective dental prosthetic materials because of the desirable bio-compatibility a nd similar tribological behaviour as the natural tooth.%在改进的微动摩擦磨损试验台上,模拟人体牙齿摩擦副,考察了天然牙以及牙科用高分子、金属和陶瓷修复材料与GCr15钢对摩的摩擦磨损性能.结果表明:天然牙的摩擦学性能优良;拜尔牙、热固塑料、铜基合金、钛及钛合金是较为理想的牙科修复材料;尤其是钛及钛合金,不但生物相容性优异,而且与天然牙摩擦学性能匹配,是最具有发展前景的牙科修复材料

  2. Effect of probe sonication and sodium hexametaphosphate on the microhardness and wear behavior of electrodeposited Ni–SiC composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Aruna, S.T., E-mail: aruna_reddy@nal.res.in; Anandan, C.; Grips, V.K. William

    2014-05-01

    Highlights: • Sodium hexametaphosphate (SHMP) explored as dispersant for SiC in Ni-bath. • SHMP and probe sonication (PS) enhances SiC incorporation in Ni matrix. • SHMP and PS enhances wear resistance and microhardness of Ni–SiC. - Abstract: Electrodeposited Ni–SiC composite coating is the most widely used engineering coating. Ni–SiC coating is bestowed with higher wear resistance and microhardness compared to plain nickel. In this study, the feasibility of using sodium hexametaphosphate as a dispersant in the electrodeposition of Ni–SiC composite coating has been investigated. The effect of sodium hexametaphosphate and probe sonication on the microhardness, microstructure and wear resistance of the electrodeposited Ni–SiC composite coating has been studied. X-ray photoelectron spectroscopy analysis of the coatings showed the absence of Na and P elements from sodium hexametaphosphate in the bath. Ni–SiC coating deposited using probe sonication followed by the addition of sodium hexametaphosphate exhibited microhardness as high as 680 HK. The microstructure of the coatings varied with probe sonication and SHMP addition and Ni–SiC–PS–SHMP coating possessed lowest roughness. This study has revealed that a synergistic combination of probe sonication of the electrolyte bath containing particles followed by sodium hexametaphosphate addition enhances the co-deposition of finer SiC particles and thereby enhances the coating properties like microhardness and wear resistance.

  3. Intonation and Compensation of Fretted String Instruments

    CERN Document Server

    Varieschi, Gabriele U

    2009-01-01

    In this paper we present mathematical models and we analyze the physics related to the problem of intonation of musical instruments such as guitars, mandolins and similar, i.e., we study how to produce perfectly in tune notes on these instruments. This analysis begins with the correct fret placement on the instrument fingerboard, following precise mathematical laws, but then it becomes increasingly complicated due to the geometrical deformation of the strings when these instruments are played, and also due to the inharmonic characteristics of the same strings. As a consequence of these factors, perfect intonation of all the notes on the instrument can never be achieved, but complex compensation procedures are introduced and studied to minimize the problem. To test the validity of these compensation procedures, we have performed extensive measurements using standard monochord sonometers and other basic acoustical devices, which confirm the correctness of our theoretical models. In particular, these experimenta...

  4. Preparation of Friction and Wear Behavior of Graphite Encapsulated Nickel Nanoparticles%石墨包裹Ni纳米颗粒的制备及其摩擦磨损性能

    Institute of Scientific and Technical Information of China (English)

    岳学庆; 段文艳; 薛云

    2011-01-01

    对膨胀石墨和Ni粉末混合物进行机械球磨并随后退火,制备出石墨包裹Ni纳米颗粒材料.通过SEM、TEM、EDS和XRD对产物进行了表征,并研究了产物作为润滑油添加剂的高温摩擦磨损性能.结果表明:制备出的石墨包裹Ni纳米颗粒直径在20~150 nrn之间,具有良好的结晶度.产物作为润滑油添加剂具有良好的高温减摩抗磨性能,且随着载荷的增大,该性能更加显著.%Graphite encapsulated nickel nanoparticles were prepared by ball-milling and subsequently annealing a mixture of expanded graphite and Ni powders. The products were characterized by SEM, TEM, EDS and XRD. The high temperature friction and wear behaviors of the products used as lubricating additive were investigated. Results showed that the graphite encapsulated nickel nanoparticles as-prepared had a size range of 20-150 nm, and exhibited a well crystallinity. The products used as lubricating additive displayed an obvious high temperature anti-friction and wear resistant effect, and larger the applied load, better the anti-friction and wear resistant effect.

  5. Microstructure and Wear Behavior of FeCoCrNiMo0.2 High Entropy Coatings Prepared by Air Plasma Spray and the High Velocity Oxy-Fuel Spray Processes

    Directory of Open Access Journals (Sweden)

    Tianchen Li

    2017-09-01

    Full Text Available In the present research, the spherical FeCoCrNiMo0.2 high entropy alloy (HEA powders with a single FCC solid solution structure were prepared by gas atomization. Subsequently, the FeCoCrNiMo0.2 coatings with a different content of oxide inclusions were prepared by air plasma spraying (APS and high-velocity oxy-fuel spraying (HVOF, respectively. The microstructure, phase composition, mechanical properties, and tribological behaviors of these HEA coatings were investigated. The results showed that both HEA coatings showed a typical lamellar structure with low porosity. Besides the primary FCC phase, a mixture of Fe2O3, Fe3O4, and AB2O4 (A = Fe, Co, Ni, and B = Fe, Cr was identified as the oxide inclusions. The oxide content of the APS coating and HVOF coating was calculated to be 47.0% and 12.7%, respectively. The wear resistance of the APS coating was approximately one order of magnitude higher than that of the HVOF coating. It was mainly attributed to the self-lubricated effect caused by the oxide films. The mass loss of the APS coating was mainly ascribed to the breakaway of the oxide film, while the main wear mechanism of the HVOF coating was the abrasive wear.

  6. FRET Fluctuation Spectroscopy of Diffusing Biopolymers: Contributions of Conformational Dynamics and Translational Diffusion

    Science.gov (United States)

    Gurunathan, Kaushik; Levitus, Marcia

    2009-01-01

    The use of Fluorescence Correlation Spectroscopy (FCS) to study conformational dynamics in diffusing biopolymers requires that the contributions to the signal due to translational diffusion are separated from those due to conformational dynamics. A simple approach that has been proposed to achieve this goal involves the analysis of fluctuations in Fluorescence Resonance Energy Transfer (FRET) efficiency. In this work, we investigate the applicability of this methodology by combining Monte Carlo simulations and experiments. Results show that diffusion does not contribute to the measured fluctuations in FRET efficiency in conditions where the relaxation time of the kinetic process is much shorter than the mean transit time of the molecules in the optical observation volume. However, in contrast to what has been suggested in previous work, the contributions of diffusion are otherwise significant. Neglecting the contributions of diffusion can potentially lead to an erroneous interpretation of the kinetic mechanisms. As an example, we demonstrate that the analysis of FRET fluctuations in terms of a purely kinetic model would generally lead to the conclusion that the system presents complex kinetic behavior even for an idealized two-state system PMID:20030305

  7. Monitoring Integrated Activity of Individual Neurons Using FRET-Based Voltage-Sensitive Dyes.

    Science.gov (United States)

    Briggman, Kevin L; Kristan, William B; González, Jesús E; Kleinfeld, David; Tsien, Roger Y

    2015-01-01

    Pairs of membrane-associated molecules exhibiting fluorescence resonance energy transfer (FRET) provide a sensitive technique to measure changes in a cell's membrane potential. One of the FRET pair binds to one surface of the membrane and the other is a mobile ion that dissolves in the lipid bilayer. The voltage-related signal can be measured as a change in the fluorescence of either the donor or acceptor molecules, but measuring their ratio provides the largest and most noise-free signal. This technology has been used in a variety of ways; three are documented in this chapter: (1) high throughput drug screening, (2) monitoring the activity of many neurons simultaneously during a behavior, and (3) finding synaptic targets of a stimulated neuron. In addition, we provide protocols for using the dyes on both cultured neurons and leech ganglia. We also give an updated description of the mathematical basis for measuring the coherence between electrical and optical signals. Future improvements of this technique include faster and more sensitive dyes that bleach more slowly, and the expression of one of the FRET pair genetically.

  8. Coverage-dependent changes of cytochrome c transverse location in phospholipid membranes revealed by FRET.

    Science.gov (United States)

    Domanov, Yegor A; Molotkovsky, Julian G; Gorbenko, Galyna P

    2005-10-01

    The method of fluorescence resonance energy transfer (FRET) has been employed to monitor cytochrome c interaction with bilayer phospholipid membranes. Liposomes composed of phosphatidylcholine and varying amounts of anionic lipid cardiolipin (CL) were used as model membranes. Trace amount of fluorescent lipid derivative, anthrylvinyl-phosphatidylcholine was incorporated into the membranes to serve energy donor for heme moiety of cytochrome c. Energy transfer efficiency was measured at different lipid and protein concentrations to obtain extensive set of data, which were further analyzed globally in terms of adequate models of protein adsorption and energy transfer on the membrane surface. It has been found that the cytochrome c association with membranes containing 10 mol% CL can be described in terms of equilibrium binding model (yielding dissociation constant Kd = 0.2-0.4 microM and stoichiometry n = 11-13 lipid molecules per protein binding site) combined with FRET model assuming uniform acceptor distribution with the distance of 3.5-3.6 nm between the bilayer midplane and heme moiety of cytochrome c. However, increasing the CL content to 20 or 40 mol% (at low ionic strength) resulted in a different behavior of FRET profiles, inconsistent with the concepts of equilibrium adsorption of cytochrome c at the membrane surface and/or uniform acceptor distribution. To explain this fact, several possibilities are analyzed, including cytochrome c-induced formation of non-bilayer structures and clusters of charged lipids, or changes in the depth of cytochrome c penetration into the bilayer depending on the protein surface density. Additional control experiments have shown that only the latter process can explain the peculiar concentration dependences of FRET at high CL content.

  9. QD-Based FRET Probes at a Glance

    Directory of Open Access Journals (Sweden)

    Armen Shamirian

    2015-06-01

    Full Text Available The unique optoelectronic properties of quantum dots (QDs give them significant advantages over traditional organic dyes, not only as fluorescent labels for bioimaging, but also as emissive sensing probes. QD sensors that function via manipulation of fluorescent resonance energy transfer (FRET are of special interest due to the multiple response mechanisms that may be utilized, which in turn imparts enhanced flexibility in their design. They may also function as ratiometric, or “color-changing” probes. In this review, we describe the fundamentals of FRET and provide examples of QD-FRET sensors as grouped by their response mechanisms such as link cleavage and structural rearrangement. An overview of early works, recent advances, and various models of QD-FRET sensors for the measurement of pH and oxygen, as well as the presence of metal ions and proteins such as enzymes, are also provided.

  10. An Experimental Study of Fretting of Gear Teeth

    Science.gov (United States)

    Krantz, Timothy L.

    2008-01-01

    Experiments were conducted to study fretting of gears. The gears were made from case-carburized AISI 9310 alloy to match the material of a flight actuator gearbox of interest. The objective of the testing was to produce damage representative of that observed on flight hardware. The following correlations and observations were noted. The amplitude of dithering motion very strongly influenced the type and magnitude of damage. Sliding amounts on the order of 30% of the width of the line contact were judged to most readily produce fretting damage. There was observed an incubation period on the order of tens-of-thousands of cycles, and the incubation period was influenced by surface roughness, torque, and the motion extent. Fretting damage could be produced for any of the torques tested, and the severity of damage increased slightly with torque. Gear teeth having surface roughness of 0.7-0.8 micrometer were somewhat more resistant to fretting than were smoother surfaces.

  11. Pulse-shaping based two-photon FRET stoichiometry.

    Science.gov (United States)

    Flynn, Daniel C; Bhagwat, Amar R; Brenner, Meredith H; Núñez, Marcos F; Mork, Briana E; Cai, Dawen; Swanson, Joel A; Ogilvie, Jennifer P

    2015-02-09

    Förster Resonance Energy Transfer (FRET) based measurements that calculate the stoichiometry of intermolecular interactions in living cells have recently been demonstrated, where the technique utilizes selective one-photon excitation of donor and acceptor fluorophores to isolate the pure FRET signal. Here, we present work towards extending this FRET stoichiometry method to employ two-photon excitation using a pulse-shaping methodology. In pulse-shaping, frequency-dependent phases are applied to a broadband femtosecond laser pulse to tailor the two-photon excitation conditions to preferentially excite donor and acceptor fluorophores. We have also generalized the existing stoichiometry theory to account for additional cross-talk terms that are non-vanishing under two-photon excitation conditions. Using the generalized theory we demonstrate two-photon FRET stoichiometry in live COS-7 cells expressing fluorescent proteins mAmetrine as the donor and tdTomato as the acceptor.

  12. Wear mechanism for spray deposited Al-Si/SiCp composites under dry sliding condition

    Institute of Scientific and Technical Information of China (English)

    滕杰; 李华培; 陈刚

    2015-01-01

    Al-Si/15%SiCp (volume fraction) composites with different silicon contents were fabricated by spray deposition technique, and typical microstructures of these composites were studied by optical microscopy (OM). Dry sliding wear tests were carried out using a block-on-ring wear machine to investigate the effect of applied load range of 10−220 N on the wear and friction behavior of these composites sliding against SAE 52100 grade bearing steel. Scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDAX) were utilized to examine the morphologies of the worn surfaces in order to observe the wear characteristics and investigate the wear mechanism. The results show that the wear behavior of these composites is dependent on the silicon content in the matrix alloy and the applied load. Al-Si/15%SiCp composites with higher silicon content exhibit better wear resistance in the applied load range. Under lower loads, the major wear mechanisms are oxidation wear and abrasive wear for all tested composites. Under higher loads, severe adhesive wear becomes the main wear mechanisms for Al-7Si/15%SiCp and Al-13Si/15%SiCp composites, while Al-20Si/15%SiCp presents a compound wear mechanism, consisting of oxidation, abrasive wear and adhesion wear.

  13. Fluorescent Proteins as Genetically Encoded FRET Biosensors in Life Sciences

    Science.gov (United States)

    Hochreiter, Bernhard; Pardo Garcia, Alan; Schmid, Johannes A.

    2015-01-01

    Fluorescence- or Förster resonance energy transfer (FRET) is a measurable physical energy transfer phenomenon between appropriate chromophores, when they are in sufficient proximity, usually within 10 nm. This feature has made them incredibly useful tools for many biomedical studies on molecular interactions. Furthermore, this principle is increasingly exploited for the design of biosensors, where two chromophores are linked with a sensory domain controlling their distance and thus the degree of FRET. The versatility of these FRET-biosensors made it possible to assess a vast amount of biological variables in a fast and standardized manner, allowing not only high-throughput studies but also sub-cellular measurements of biological processes. In this review, we aim at giving an overview over the recent advances in genetically encoded, fluorescent-protein based FRET-biosensors, as these represent the largest and most vividly growing group of FRET-based sensors. For easy understanding, we are grouping them into four categories, depending on their molecular mechanism. These are based on: (a) cleavage; (b) conformational-change; (c) mechanical force and (d) changes in the micro-environment. We also address the many issues and considerations that come with the development of FRET-based biosensors, as well as the possibilities that are available to measure them. PMID:26501285

  14. Fluorescent Proteins as Genetically Encoded FRET Biosensors in Life Sciences

    Directory of Open Access Journals (Sweden)

    Bernhard Hochreiter

    2015-10-01

    Full Text Available Fluorescence- or Förster resonance energy transfer (FRET is a measurable physical energy transfer phenomenon between appropriate chromophores, when they are in sufficient proximity, usually within 10 nm. This feature has made them incredibly useful tools for many biomedical studies on molecular interactions. Furthermore, this principle is increasingly exploited for the design of biosensors, where two chromophores are linked with a sensory domain controlling their distance and thus the degree of FRET. The versatility of these FRET-biosensors made it possible to assess a vast amount of biological variables in a fast and standardized manner, allowing not only high-throughput studies but also sub-cellular measurements of biological processes. In this review, we aim at giving an overview over the recent advances in genetically encoded, fluorescent-protein based FRET-biosensors, as these represent the largest and most vividly growing group of FRET-based sensors. For easy understanding, we are grouping them into four categories, depending on their molecular mechanism. These are based on: (a cleavage; (b conformational-change; (c mechanical force and (d changes in the micro-environment. We also address the many issues and considerations that come with the development of FRET-based biosensors, as well as the possibilities that are available to measure them.

  15. Fluorescent proteins as genetically encoded FRET biosensors in life sciences.

    Science.gov (United States)

    Hochreiter, Bernhard; Garcia, Alan Pardo; Schmid, Johannes A

    2015-10-16

    Fluorescence- or Förster resonance energy transfer (FRET) is a measurable physical energy transfer phenomenon between appropriate chromophores, when they are in sufficient proximity, usually within 10 nm. This feature has made them incredibly useful tools for many biomedical studies on molecular interactions. Furthermore, this principle is increasingly exploited for the design of biosensors, where two chromophores are linked with a sensory domain controlling their distance and thus the degree of FRET. The versatility of these FRET-biosensors made it possible to assess a vast amount of biological variables in a fast and standardized manner, allowing not only high-throughput studies but also sub-cellular measurements of biological processes. In this review, we aim at giving an overview over the recent advances in genetically encoded, fluorescent-protein based FRET-biosensors, as these represent the largest and most vividly growing group of FRET-based sensors. For easy understanding, we are grouping them into four categories, depending on their molecular mechanism. These are based on: (a) cleavage; (b) conformational-change; (c) mechanical force and (d) changes in the micro-environment. We also address the many issues and considerations that come with the development of FRET-based biosensors, as well as the possibilities that are available to measure them.

  16. Indicators based on fluorescence resonance energy transfer (FRET).

    Science.gov (United States)

    Tsien, Roger Y

    2009-07-01

    One of the major new trends in the design of indicators for optically imaging biochemical and physiological functions of living cells has been the exploitation of fluorescence resonance energy transfer (FRET). FRET is a well-known spectroscopic technique for monitoring changes in the proximity and mutual orientation of pairs of chromophores. It has long been used in biochemistry and cell biology to assess distances and orientations between specific labeling sites within a single macromolecule or between two separate molecules. More recently, macromolecules or molecular pairs have been engineered to change their FRET in response to biochemical and physiological signals such as membrane potential, cyclic AMP (cAMP), protease activity, free Ca(2+) and Ca(2+)-calmodulin (CaM) concentrations, protein-protein heterodimerization, phosphorylation, and reporter-gene expression. Because FRET is general, nondestructive, and easily imaged, it has proven to be one of the most versatile spectroscopic readouts available to the designer of new probes. FRET is particularly amenable to emission ratioing, which is more reliably quantifiable than single-wavelength monitoring and better suited than excitation ratioing to high-speed and laser-excited imaging. This article summarizes the photophysical principles of FRET and the types of indicators used.

  17. FRET-based identification of mRNAs undergoing translation.

    Directory of Open Access Journals (Sweden)

    Benjamin Stevens

    Full Text Available We present proof-of-concept in vitro results demonstrating the feasibility of using single molecule fluorescence resonance energy transfer (smFRET measurements to distinguish, in real time, between individual ribosomes programmed with several different, short mRNAs. For these measurements we use either the FRET signal generated between two tRNAs labeled with different fluorophores bound simultaneously in adjacent sites to the ribosome (tRNA-tRNA FRET or the FRET signal generated between a labeled tRNA bound to the ribosome and a fluorescent derivative of ribosomal protein L1 (L1-tRNA FRET. With either technique, criteria were developed to identify the mRNAs, taking into account the relative activity of the mRNAs. These criteria enabled identification of the mRNA being translated by a given ribosome to within 95% confidence intervals based on the number of identified FRET traces. To upgrade the approach for natural mRNAs or more complex mixtures, the stoichiometry of labeling should be enhanced and photobleaching reduced. The potential for porting these methods into living cells is discussed.

  18. FRET-based identification of mRNAs undergoing translation.

    Science.gov (United States)

    Stevens, Benjamin; Chen, Chunlai; Farrell, Ian; Zhang, Haibo; Kaur, Jaskiran; Broitman, Steven L; Smilansky, Zeev; Cooperman, Barry S; Goldman, Yale E

    2012-01-01

    We present proof-of-concept in vitro results demonstrating the feasibility of using single molecule fluorescence resonance energy transfer (smFRET) measurements to distinguish, in real time, between individual ribosomes programmed with several different, short mRNAs. For these measurements we use either the FRET signal generated between two tRNAs labeled with different fluorophores bound simultaneously in adjacent sites to the ribosome (tRNA-tRNA FRET) or the FRET signal generated between a labeled tRNA bound to the ribosome and a fluorescent derivative of ribosomal protein L1 (L1-tRNA FRET). With either technique, criteria were developed to identify the mRNAs, taking into account the relative activity of the mRNAs. These criteria enabled identification of the mRNA being translated by a given ribosome to within 95% confidence intervals based on the number of identified FRET traces. To upgrade the approach for natural mRNAs or more complex mixtures, the stoichiometry of labeling should be enhanced and photobleaching reduced. The potential for porting these methods into living cells is discussed.

  19. Development of Ti-C-N coatings with improved tribological behavior and antibacterial properties.

    Science.gov (United States)

    Sáenz de Viteri, Virginia; Barandika, Gotzone; Bayón, Raquel; Fernández, Xana; Ciarsolo, Iñigo; Igartua, Amaya; Pérez Tanoira, Ramón; Moreno, Jaime Esteban; Peremarch, Conchita Pérez-Jorge

    2015-03-01

    In artificial metallic joint implants, the failure is provoked by two effects in most of the cases: mass loss and wear debris removed due to tribological-corrosive effects on the implant alloy, and infections due to the presence of bacteria. In this work, several Ti-C-N corrosion and wear protective coatings were developed by Physical Vapour Deposition technology, and deposited on Ti6Al4V alloy. In order to provide the implant antibacterial properties, an additional silver top coating has been deposited. Tribological behavior was characterized through tribocorrosion and fretting tests. On the other hand, wettability tests were performed to study the grade of hydrophilicity/hydrophobia. Additionally, antibacterial properties were evaluated by means of bacterial adhesion tests. As a result of these characterization studies, the coating with the best performance was selected. The as-coated material includes excellent protection against tribocorrosion and fretting effects (in relation to the uncoated one) and the silver layer has been confirmed to exhibit antibacterial properties.

  20. Fluorescent Protein Based FRET Pairs with Improved Dynamic Range for Fluorescence Lifetime Measurements.

    Directory of Open Access Journals (Sweden)

    Bobin George Abraham

    Full Text Available Fluorescence Resonance Energy Transfer (FRET using fluorescent protein variants is widely used to study biochemical processes in living cells. FRET detection by fluorescence lifetime measurements is the most direct and robust method to measure FRET. The traditional cyan-yellow fluorescent protein based FRET pairs are getting replaced by green-red fluorescent protein variants. The green-red pair enables excitation at a longer wavelength which reduces cellular autofluorescence and phototoxicity while monitoring FRET. Despite the advances in FRET based sensors, the low FRET efficiency and dynamic range still complicates their use in cell biology and high throughput screening. In this paper, we utilized the higher lifetime of NowGFP and screened red fluorescent protein variants to develop FRET pairs with high dynamic range and FRET efficiency. The FRET variations were analyzed by proteolytic activity and detected by steady-state and time-resolved measurements. Based on the results, NowGFP-tdTomato and NowGFP-mRuby2 have shown high potentials as FRET pairs with large fluorescence lifetime dynamic range. The in vitro measurements revealed that the NowGFP-tdTomato has the highest Förster radius for any fluorescent protein based FRET pairs yet used in biological studies. The developed FRET pairs will be useful for designing FRET based sensors and studies employing Fluorescence Lifetime Imaging Microscopy (FLIM.

  1. Effect of electroless nickel interlayer on wear behavior of CrN/ZrN multilayer films on Cu-alloyed ductile iron

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chung-Kwei [School of Dental Technology, College of Oral Medicine, Taipei Medical University, Taipei, 110, Taiwan (China); Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei, 110, Taiwan (China); Hsu, Cheng-Hsun, E-mail: chhsu@ttu.edu.tw [Research Center for Biomedical Implants and Microsurgery Devices, Taipei Medical University, Taipei, 110, Taiwan (China); Department of Materials Engineering, Tatung University, Taipei, 104, Taiwan (China); Kung, Shu-Chi [Department of Materials Engineering, Tatung University, Taipei, 104, Taiwan (China)

    2013-11-01

    This study utilized electroless nickel as an interlayer, then coated nanoscale CrN/ZrN multilayer on Cu-alloyed ductile iron through cathodic arc deposition method. Morphology and structure of the coatings were analyzed by using field emission scanning electron microscopy (FESEM), X-ray diffractometer (XRD), and transmission electron microscopy (TEM). Moreover, Rockwell-C indentation, nanoindention, and ball-on-disk wear tests were all carried out to explore the properties of the coatings consisting of adhesion, hardness, elastic modulus, friction coefficient, and wear rate, respectively. The results showed that electroless nickel had a major amorphous phase while the CrN/ZrN multilayer coatings exhibited alternate nanocrystalline CrN and ZrN phases. Compared with single coating of electroless nickel or CrN/ZrN, the CrN/ZrN multilayer coatings with an electroless nickel interlayer exhibited higher hardness (31.1 GPa) and elastic modulus (256.4 GPa). Consequently, the ductile iron with the duplex coatings could be available to reduce both the friction coefficient and wear rate.

  2. 人牙釉质在柠檬酸介质中的摩擦磨损行为研究%Friction and Wear Behaviors of Human Tooth Enamel in Citric Acid Solution

    Institute of Scientific and Technical Information of China (English)

    黄欢; 郑靖; 钱林茂

    2011-01-01

    By using a reciprocating sliding wear test machine, friction and wear behaviors of human tooth enamel opposite to titanium alloy have been investigated in citric acid solution ( pH = 3.2). The results showed that human tooth enamel exhibited different tribological behaviors in two different media, i.e. citric acid solution and artificial saliva. Due to the enamel surface softening and demineralization caused by acid - attack, the friction coefficient was lower and fluctuated more significantly in citric acid solution than in artificial saliva. The worn surface was characterized mainly by adhesive delamination. Wear volume almost increased linearly with the number of cycles in citric acid solution, which was bigger than that in artificial saliva.%采用往复滑动摩擦磨损试验台,以TC4钛合金球为摩擦偶件,考察了人牙釉质在Ph为3.2的柠檬酸介质中的摩擦磨损行为,并与人工唾液介质中的结果进行对比.结果表明:牙釉质在不同介质中的摩擦磨损行为存在显著差异.在柠檬酸介质中,鉴于柠檬酸对牙釉质表面的酸蚀软化和脱矿作用,牙釉质的摩擦系数低于人工唾液介质,但伴随显著波动,磨损机制以黏着剥落为主,磨损体积随循环次数增加几乎呈线性增长,磨损量明显大于人工唾液介质.

  3. Influence of halogen irradiance on short- and long-term wear resistance of resin-based composite materials.

    LENUS (Irish Health Repository)

    Bhamra, Gurcharn S

    2009-02-01

    The Oregon Health Science University (OHSU) four-chamber oral wear simulator was used to examine the impact of halogen irradiance on the short- and long-term wear behavior of four-methacrylate resin-based composites (RBCs). The hypothesis proposed was that exacerbated wear would occur following the long-term wear of RBCs irradiated under non-optimized irradiance conditions.

  4. 纤维增强铸型尼龙在水润滑条件下的摩擦磨损性能研究%Investigation of the Friction and Wear Behavior of Fiber Reinforced MC Nylon Under Water Lubrication

    Institute of Scientific and Technical Information of China (English)

    李国禄; 王昆林; 刘金海; 刘家浚

    2001-01-01

    考察了玻璃纤维和碳纤维增强MC尼龙在水润滑条件下的摩擦磨损特性,并借助扫描电子显微镜和表面形貌仪分析了磨损机理.结果表明:在水润滑条件下,纤维增强MC尼龙的摩擦系数比干摩擦下的低,耐磨性优于未增强的基体材料;其中碳纤维增强MC尼龙比玻璃纤维增强MC尼龙具有更低的摩擦系数和更高的耐磨性能;碳纤维增强MC尼龙的磨损机理主要是粘着转移,同时伴有犁削作用,而玻璃纤维增强MC尼龙的磨损机理主要是犁削作用.%The friction and wear behaviors of glass fiber an d carbon fiber reinforced MC nylon composites (coded as GF/MCPA and CF/MCPA, res pectively) under water lubrication were investigated with an MM-200 friction an d wear tester. The worn surfaces and wear debris were observed and analyzed usin g a scanning electron microscope and a surface profilometer. The results show th at fiber reinforced MC nylon composite sliding against AISI1045 steel under wate r lubrication registers lower friction coefficients than under dry sliding and t he wear resistance of the reinforced composites is better than that of MC nylon matrix. Of the two composites, CF/MCPA has smaller friction coefficient and high er wear resistance than GF/MCPA. This is attributed to the formation of a unifor m and continuous transfer film on the counterpart steel surface sliding against CF/MCPA. CF/MCPA is characterized by adhesion and transfer, accompanied by sligh t plowing in sliding against steel, while GF/MCPA is characterized by micro-cut ting.

  5. Control of erosive tooth wear: possibilities and rationale

    Directory of Open Access Journals (Sweden)

    Mônica Campos Serra

    2009-06-01

    Full Text Available Dental erosion is a type of wear caused by non bacterial acids or chelation. There is evidence of a significant increase in the prevalence of dental wear in the deciduous and permanent teeth as a consequence of the frequent intake of acidic foods and drinks, or due to gastric acid which may reach the oral cavity following reflux or vomiting episodes. The presence of acids is a prerequisite for dental erosion, but the erosive wear is complex and depends on the interaction of biological, chemical and behavioral factors. Even though erosion may be defined or described as an isolated process, in clinical situations other wear phenomena are expected to occur concomitantly, such as abrasive wear (which occurs, e.g, due to tooth brushing or mastication. In order to control dental loss due to erosive wear it is crucial to take into account its multifactorial nature, which predisposes some individuals to the condition.

  6. Wear of nanofilled dental composites in a newly-developed in vitro testing device

    Science.gov (United States)

    Lawson, Nathaniel C.

    Purpose. In vivo wear of dental composites can lead to loss of individual tooth function and the need to replace a composite restoration. To evaluate the wear performance of new and existing dental composites, we developed a novel system for measuring in vitro wear and we used this system to analyze the mechanisms of wear of nanofilled composite materials. Methods. A modified wear testing device was designed based on the Alabama wear testing machine. The new device consists of: (1) an antagonist which is lowered to and raised from the composite specimen by weight loading, (2) a motorized stage to cause the antagonist to slide 2mm on the composite surface, and (3) pumps for applying lubricant to the specimens. Various testing parameters of the device were examined before testing, including the impulse force, the third-body medium, the lubricant and antagonist. The parameters chosen for this study were 20N at 1Hz with a 33% glycerine lubricant and stainless steel antagonist. Three nano-composites were fabricated with a BisGMA polymer matrix and 40nm SiO2 filler particles at three filler loads (25%, 50% and 65%). The mechanical properties of the composites were measured. The materials were then tested in the modified wear testing device under impact wear, sliding wear and a combination of impact and sliding wear. The worn surfaces were then analyzed with a non-contact profilometer and SEM. Results. The volumetric wear data indicated that increasing filler content beyond 25% decreased the wear resistance of the composites. Increasing filler content increased hardness and decreased toughness. SEM evaluation of the worn specimens indicated that the 25% filled materials failed by fatigue and the 50% and 65% filled materials failed by abrasive wear. Impact wear produced fretting in this device and sliding wear is more aggressive than impact wear. Conclusion. Based on the results of this study and previous studies on this topic, manufacturers are recommended to use a filler

  7. A comparative study of sliding wear of nonmetallic dental restorative materials with emphasis on micromechanical wear mechanisms.

    Science.gov (United States)

    Dupriez, Nataliya Deyneka; von Koeckritz, Ann-Kristin; Kunzelmann, Karl-Heinz

    2015-05-01

    The purpose of this study is to investigate the in vitro tribological behavior of modern nonmetallic restorative materials. Specimen prepared of IPS e.max Press lithium disilicate glass ceramic, IPS Empress Esthetic leucite-reinforced glass ceramic, Everest ZS Blanks yttria-stabilized zirconia and Lava Ultimate composite were subjected to wear using a wear machine designed to simulate occlusal loads. The wear of the investigated materials and antagonists were evaluated by a three-dimensional surface scanner. The quantitative wear test results were used to compare and rank the materials. Specimens were divided into two groups with steatite and alumina antagonists. For each antagonist material an analysis of variance was applied. As a post hoc test of the significant differences, Tukey's honest significant difference test was used. With steatite antagonist: wear of zirconia materials mechanical properties (hardness and fracture toughness) and with materials microstructure. Wear mechanisms are discussed. © 2014 Wiley Periodicals, Inc.

  8. Effect of bionic coupling units' forms on wear resistance of gray cast iron under dry linear reciprocating sliding condition

    Science.gov (United States)

    Pang, Zuobo; Zhou, Hong; Xie, Guofeng; Cong, Dalong; Meng, Chao; Ren, Luquan

    2015-07-01

    In order to get close to the wear form of guide rails, the homemade linear reciprocating wear testing machine was used for the wear test. In order to improve the wear-resistance of gray cast iron guide rail, bionic coupling units of different forms were manufactured by a laser. Wear behavior of gray-cast-iron with bionic-coupling units has been studied under dry sliding condition at room temperature using the wear testing machine. The wear resistance was evaluated by means of weight loss measurement and wear morphology. The results indicated that bionic coupling unit could improve the wear resistance of gray cast iron. The wear resistance of gray cast iron with reticulation bionic coupling unit is the best. When the load and speed changed, reticulation bionic coupling unit still has excellent performance in improving the wear resistance of gray cast iron.

  9. Effects of rare earths on friction and wear characteristics of magnesium alloy AZ91D

    Institute of Scientific and Technical Information of China (English)

    祁庆琚; 刘勇兵; 杨晓红

    2003-01-01

    The influence of various rare-earth contents on the friction and wear characteristics of magnesium alloyAZ91D was studied. The results show that the wear resistance properties of rare-earth magnesium alloys are betterthan those of the matrix alloy under the testing conditions. Magnesium alloys undergo transition from mild wear tosevere wear. The addition of rare earths refines the structure of alloys, improves the comprehensive behaviors of themagnesium alloys, increases the stability of oxidation films on worn surfaces, enhances the loading ability of rare-earth magnesium alloys, and delays the transition from mild wear to severe wear effectively.

  10. Intravital imaging of fluorescent markers and FRET probes by DNA tattooing

    Directory of Open Access Journals (Sweden)

    Spencer David M

    2007-01-01

    Full Text Available Abstract Background Advances in fluorescence microscopy and mouse transgenesis have made it possible to image molecular events in living animals. However, the generation of transgenic mice is a lengthy process and intravital imaging requires specialized knowledge and equipment. Here, we report a rapid and undemanding intravital imaging method using generally available equipment. Results By DNA tattooing we transfect keratinocytes of living mice with DNA encoding fluorescent biosensors. Subsequently, the behavior of individual cells expressing these biosensors can be visualized within hours and using conventional microscopy equipment. Using this "instant transgenic" model in combination with a corrected coordinate system, we followed the in vivo behavior of individual cells expressing either FRET- or location-based biosensors for several days. The utility of this approach was demonstrated by assessment of in vivo caspase-3 activation upon induction of apoptosis. Conclusion This "instant skin transgenic" model can be used to follow the in vivo behavior of individual cells expressing either FRET- or location-based probes for several days after tattooing and provides a rapid and inexpensive method for intravital imaging in murine skin.

  11. On the Prospects of Using Nanoindentation and Wear Test to Study the Mechanical Behavior of Fe-Based Metallic Glass Coating Reinforced by B4C Nanoparticles

    Science.gov (United States)

    Movahedi, Behrooz

    2017-03-01

    In this study, Fe-based metallic glass was served as the matrix in which various ratios of hard B4C nanoparticles as reinforcing agents were prepared using a high-energy mechanical milling. The feedstock nanocomposite powders were transferred to the coatings using a high-velocity oxygen fuel process. The results showed that the microstructure of the nanocomposite coating was divided into two regions, namely a full amorphous phase region and homogeneous dispersion of B4C nanoparticles with a scale of 10 to 50 nm in a residual amorphous matrix. As the B4C content is increased, the hardness of the composite coatings is increased too, but the fracture toughness begins to be decreased at the B4C content higher than 20 vol pct. The optimal mechanical properties are obtained with 15 vol pct B4C due to the suitable content and uniform distribution of nanoparticles. The addition of 15 vol pct B4C to the Fe-based metallic glass matrix reduced the friction coefficient from 0.49 to 0.28. The average specific wear rate of the nanocomposite coating (0.48 × 10-5 mm3 Nm-1) was much less than that for the single-phase amorphous coating (1.23 × 10-5 mm3Nm-1). Consequently, the changes in wear resistance between both coatings were attributed to the changes in the brittle to ductile transition by adding B4C reinforcing nanoparticles.

  12. On the Prospects of Using Nanoindentation and Wear Test to Study the Mechanical Behavior of Fe-Based Metallic Glass Coating Reinforced by B4C Nanoparticles

    Science.gov (United States)

    Movahedi, Behrooz

    2017-01-01

    In this study, Fe-based metallic glass was served as the matrix in which various ratios of hard B4C nanoparticles as reinforcing agents were prepared using a high-energy mechanical milling. The feedstock nanocomposite powders were transferred to the coatings using a high-velocity oxygen fuel process. The results showed that the microstructure of the nanocomposite coating was divided into two regions, namely a full amorphous phase region and homogeneous dispersion of B4C nanoparticles with a scale of 10 to 50 nm in a residual amorphous matrix. As the B4C content is increased, the hardness of the composite coatings is increased too, but the fracture toughness begins to be decreased at the B4C content higher than 20 vol pct. The optimal mechanical properties are obtained with 15 vol pct B4C due to the suitable content and uniform distribution of nanoparticles. The addition of 15 vol pct B4C to the Fe-based metallic glass matrix reduced the friction coefficient from 0.49 to 0.28. The average specific wear rate of the nanocomposite coating (0.48 × 10-5 mm3 Nm-1) was much less than that for the single-phase amorphous coating (1.23 × 10-5 mm3Nm-1). Consequently, the changes in wear resistance between both coatings were attributed to the changes in the brittle to ductile transition by adding B4C reinforcing nanoparticles.

  13. Friction and Wear Behavior of Rock Bit Bearing Unit Specimens%牙轮钻头轴承单元试件的摩擦磨损性能

    Institute of Scientific and Technical Information of China (English)

    王国荣; 钟林; 杨昌海; 陈林燕

    2013-01-01

    Because of the small structure size,high working load and temperature,and poor lubrication condition,the main failure of rock bit bearing is caused by friction and wear.In order to improve the bearing lubrication performance and service life,the mathematical model of fluid lubrication of rock bit bearing was built through simulating the working conditions of rock bit bearing units,and the variations of friction coefficient,wear capacity and temperature of rock bit bearing unit specimens under different conditions were studied on MMW-1 universal testing friction and wear machine with bearing materials of 20CrNiMo as pin and beryllium bronze as disc.The results show that,on the simulated operating conditions of rock bit bearing,the friction coefficient of the pin-disc specimens is increased as the load increasing at constant rotation speed,and reduced as the rotation speed increasing at constant load.The temperatures of the specimens and the grease are increased with the increase of load and speed,and at the load of 120 ~ 200 N and the speed of 60 ~ 192 r/min,the temperatures of the specimens and the grease maintain at a lower value of about 40 ℃,that is a better lubrication performance is got.The wear surface morphology analysis shows that the adhesive wear results in the failure of rock bit bearing.%由于牙轮钻头轴承的结构尺寸小、工作载荷大、温度高、润滑条件差等,导致其失效主要为摩擦磨损.为了提高轴承的润滑性能和使用寿命,模拟牙轮钻头轴承单元工况,建立其流体润滑的数学模型;分别以牙轮钻头轴承单元材料20CrNiMo和铍青铜为销和盘,在MMW-1型万能摩擦磨损试验机上研究不同工况下试件的摩擦因数、磨损量及温度变化.结果表明:在牙轮钻头轴承模拟工况下,当转速一定时,试件的摩擦因数随载荷的增大而增大,当载荷一定时,摩擦因数随着转速升高而逐渐降低;试件及润滑脂的温度随载荷和转速

  14. Optical wear monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Kidane, Getnet S; Desilva, Upul P.; He, Chengli; Ulerich, Nancy H.

    2016-07-26

    A gas turbine includes first and second parts having outer surfaces located adjacent to each other to create an interface where wear occurs. A wear probe is provided for monitoring wear of the outer surface of the first part, and includes an optical guide having first and second ends, wherein the first end is configured to be located flush with the outer surface of the first part. A fiber bundle includes first and second ends, the first end being located proximate to the second end of the optical guide. The fiber bundle includes a transmit fiber bundle comprising a first plurality of optical fibers coupled to a light source, and a receive fiber bundle coupled to a light detector and configured to detect reflected light. A processor is configured to determine a length of the optical guide based on the detected reflected light.

  15. Wave propagation in coated cylinders with reference to fretting fatigue

    Indian Academy of Sciences (India)

    M Ramesh; Satish V Kailas; K R Y Simha

    2008-06-01

    Fretting fatigue is the phenomenon of crack initiation due to dynamic contact loading, a situation which is commonly encountered in mechanical couplings subjected to vibration. The study of fretting fatigue in high frequency regime has gained importance in recent years. However the stress wave effects at high frequency y loading is scanty in the literature. The objective of present investigation is to study stress wave propagation in cylinders with reference to high frequency fretting. The case of a coated cylinder is considered since coating is often provided to improve tribological properties of the component. Rule of mixtures is proposed to understand the dispersion phenomenon in coated or layered cylinder knowing the dispersion relation for the cases of homogeneous cylinders made of coating and substrate materials separately. The possibility of stress wave propagation at the interface with a particular phase velocity without dispersion is also discussed. Results are given for two different thicknesses of coating.

  16. Borromean three-body FRET in frozen Rydberg gases

    Science.gov (United States)

    Faoro, R.; Pelle, B.; Zuliani, A.; Cheinet, P.; Arimondo, E.; Pillet, P.

    2015-09-01

    Controlling the interactions between ultracold atoms is crucial for quantum simulation and computation purposes. Highly excited Rydberg atoms are considered in this prospect for their strong and controllable interactions known in the dipole-dipole case to induce non-radiative energy transfers between atom pairs, similarly to fluorescence resonance energy transfer (FRET) in biological systems. Here we predict few-body FRET processes in Rydberg atoms and observe the first three-body resonance energy transfer in cold Rydberg atoms using cold caesium atoms. In these resonances, additional relay atoms carry away an energy excess preventing the two-body resonance, leading thus to a Borromean type of energy transfer. These few-body processes present strong similarities with multistep FRET between chromophores sometimes called donor-bridge-acceptor or superexchange. Most importantly, they generalize to any Rydberg atom and could lead to new implementations of few-body quantum gates or entanglement.

  17. A portable FRET analyzer for rapid detection of sugar content.

    Science.gov (United States)

    Kim, Haseong; Kim, Hyo Sang; Ha, Jae-Seok; Lee, Seung-Goo

    2015-05-21

    Fluorescence resonance energy transfer (FRET) is widely used as a core process in biometric sensors to detect small molecules such as sugars, calcium ions, or amino acids. However, FRET based biosensors with innate weak signal intensity require the use of expensive, high-sensitive equipment. In the present study, these shortcomings were overcome with the fabrication of a sensitive, inexpensive, and portable analyzer which provides quantitative detection of small molecules in a liquid sample. The usability of the developed analyzer was successfully tested by measuring sucrose and maltose contents in commercially available beverage samples, with better performance than the conventional monochromator-type spectrofluorometer. It is anticipated that miniaturization of the equipment and improving the FRET based biosensors will contribute to the practical use of this hand-held analyzer in conditions where high-end equipment is not available.

  18. PixFRET, an ImageJ plug-in for FRET calculation that can accommodate variations in spectral bleed-throughs.

    Science.gov (United States)

    Feige, Jérôme N; Sage, Daniel; Wahli, Walter; Desvergne, Béatrice; Gelman, Laurent

    2005-09-01

    Fluorescence resonance energy transfer (FRET) allows the user to investigate interactions between fluorescent partners. One crucial issue when calculating sensitized emission FRET is the correction for spectral bleed-throughs (SBTs), which requires to calculate the ratios between the intensities in the FRET and in the donor or acceptor settings, when only the donor or acceptor are present. Theoretically, SBT ratios should be constant. However, experimentally, these ratios can vary as a function of fluorophore intensity, and assuming constant values may hinder precise FRET calculation. One possible cause for such a variation is the use of a microscope set-up with different photomultipliers for the donor and FRET channels, a set-up allowing higher speed acquisitions on very dynamic fluorescent molecules in living cells. Herein, we show that the bias introduced by the differential response of the two PMTs can be circumvented by a simple modeling of the SBT ratios as a function of fluorophore intensity. Another important issue when performing FRET is the localization of FRET within the cell or a population of cells. We hence developed a freely available ImageJ plug-in, called PixFRET, that allows a simple and rapid determination of SBT parameters and the display of normalized FRET images. The usefulness of this modeling and of the plug-in are exemplified by the study of FRET in a system where two interacting nuclear receptors labeled with ECFP and EYFP are coexpressed in living cells.

  19. Simultaneous quantitative live cell imaging of multiple FRET-based biosensors.

    Directory of Open Access Journals (Sweden)

    Andrew Woehler

    Full Text Available We have developed a novel method for multi-color spectral FRET analysis which is used to study a system of three independent FRET-based molecular sensors composed of the combinations of only three fluorescent proteins. This method is made possible by a novel routine for computing the 3-D excitation/emission spectral fingerprint of FRET from reference measurements of the donor and acceptor alone. By unmixing the 3D spectrum of the FRET sample, the total relative concentrations of the fluorophores and their scaled FRET efficiencies are directly measured, from which apparent FRET efficiencies can be computed. If the FRET sample is composed of intramolecular FRET sensors it is possible to determine the total relative concentration of the sensors and then estimate absolute FRET efficiency of each sensor. Using multiple tandem constructs with fixed FRET efficiency as well as FRET-based calcium sensors with novel fluorescent protein combinations we demonstrate that the computed FRET efficiencies are accurate and changes in these quantities occur without crosstalk. We provide an example of this method's potential by demonstrating simultaneous imaging of spatially colocalized changes in [Ca(2+], [cAMP], and PKA activity.

  20. Friction and Wear of Sintered Alumina at High Temperature

    OpenAIRE

    Senda, Tetsuya; TAKAHASHl, Chiori; UEMATSU, Susumu; Amada, Shigeyasu

    1991-01-01

    The frictional behavior of alumina ceramics was investigated at various temperatures up to 1200℃. The coefficient of friction decreased with increasing temperature and this temperature dependency became more pronounced as higher contact pressures were applied. Wear loss at room temperature could be interpreted as being caused by one of either two different behavior modes. These have a rate difference of a factor of ten. At temperatures higher than 800℃, the wear loss was far less than that at...

  1. Intravital FRET: Probing Cellular and Tissue Function in Vivo

    Directory of Open Access Journals (Sweden)

    Helena Radbruch

    2015-05-01

    Full Text Available The development of intravital Förster Resonance Energy Transfer (FRET is required to probe cellular and tissue function in the natural context: the living organism. Only in this way can biomedicine truly comprehend pathogenesis and develop effective therapeutic strategies. Here we demonstrate and discuss the advantages and pitfalls of two strategies to quantify FRET in vivo—ratiometrically and time-resolved by fluorescence lifetime imaging—and show their concrete application in the context of neuroinflammation in adult mice.

  2. Rupture pressure of wear degraded alloy 600 steam generator tubings

    Science.gov (United States)

    Hwang, Seong Sik; Namgung, Chan; Jung, Man Kyo; Kim, Hong Pyo; Kim, Joung Soo

    2008-02-01

    Fretting/wear degradation at the tube support in the U-bend region of a steam generator (SG) of a pressurized water reactor (PWR) has been reported. Simulated fretted flaws were machined on SG tubes of 195 mm in length. A pressure test was carried out with the tubes at room temperature by using a high pressure test facility which consisted of a water pressurizing pump, a test specimen section and a control unit. Water leak rates just after a ligament rupture or a burst were measured. Tubes degraded by up to 70% of the tube wall thickness (TW) showed a high safety margin in terms of the burst pressure during normal operating conditions. Tubes degraded by up to 50% of the TW did not show burst. Burst pressure depended on the defect depths rather than on the wrap angles. The tube with a wrap angle of 0° showed a fish mouth fracture, whereas the tube with a 45° wrap angle showed a three way fracture.

  3. Wear resistant zirconium base alloy article for water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Gillett, J.E.; Shockling, L.A.; Sherwood, D.G.

    1988-03-01

    In a water reactor operating environment, the combination having improved fretting wear resistance is described comprising: an elongated tubular water displacer rod; having a low neutron absorption cross section guide support plates distributed along the length of the water displacer rod; the water displacer rod intersecting the guide support plates through apertures in the guide support plates; the water displacer rod having a plurality of spaced apart annular electrospark deposited coatings, each coating facing the wall of a respective aperture, the electrospark deposited coatings comprising Cr/sub 2/C/sub 3/; wherein the water displacer rod has a tube wall composed of a zirconium base alloy; and wherein the guide support plates are composed of a stainless steel alloy.

  4. Comparative wear mapping techniques

    DEFF Research Database (Denmark)

    Alcock, J.; Sørensen, Ole Toft; Jensen, S.

    1996-01-01

    Pin surfaces were analysed by laser profilometry. Two roughness parameters, R(a) and the fractal dimension, were investigated as a first step towards methods of quantitative wear mechanism mapping. Both parameters were analysed for their relationship to the severity and prevalence of a mechanism....

  5. RH炉浸渍管用镁铬砖的损毁行为分析%Analyzing the Wear Behavior of Magnesia Chromite Brick (MKB)Used in RH Snorkel

    Institute of Scientific and Technical Information of China (English)

    陈希来; 李亚伟; 徐国涛; 薛改凤; 邹龙; 刘黎

    2011-01-01

    Used MKB in RH Snorkel of WISCO was analyzed by means of ICP-AES, XRD, optical microscope,SEM and mercury porosimetry ,and the aim is to clarify the wear behavior of MKB. The results show that adhering slag and cracks are found in the used MKB. The penetration and corrosion layer are mainly constituted by low-melting point cacoclasite and iron as well as its oxides. There is a dense layer with 40μm thickness formed between the penetration and corrosion layer and initial MKB, which mainly consists of FeO and MgO-Al2O3 spinel. The wear behavior of MKB includes two stages. Firstly, molten slag and steel can easily penetrate the open pores of MKB due to its high apparent porosity and large pore diameter,and then the penetrated slag and steel accelerate the erosion and peeling off of MKB. Thus, improving the porous characteristics will be an important route to decrease or inhibit the wear of MKB.%利用化学分析、X射线衍射仪、光学显微镜、扫描电镜及压汞仪等方法对武钢RH精炼炉浸渍管用后镁铬残砖进行了分析,旨在找出镁铬砖的损毁行为.结果表明:残砖粘渣且存有裂纹.残砖渗透、侵蚀层主要有低熔点的钙铝黄长石和铁及其氧化物;在渗透、侵蚀层与原砖层之间存在由FeO和镁铝尖晶石组成的约40 μm厚的致密过度层.镁铬砖的损毁主要包括2部分,前期主要是砖体气孔率高、气孔直径大造成的熔渣及钢水渗透,后期是渗透的熔渣及钢水加剧砖体的溶蚀及热剥落;因此改善镁铬砖的气孔特性将会成为减缓其损毁的重要途径.

  6. The Effect of the Nanometer Silver Antibacterial Finishing to the Wear Behavior of Knitwear%纳米银抗菌整理对贴身针织物舒适性的影响

    Institute of Scientific and Technical Information of China (English)

    叶海莲; 包静; 周景

    2009-01-01

    对真丝、棉、羊毛、涤纶、锦纶等常用针织服装贴身面料进行DF纳米银抗菌整理,测试整理前后针织面料的金黄色葡萄球菌的抗菌性能和抗菌耐洗度,以及整理前后织物的透气透湿性、回潮率和抗静电等服用舒适性能的变化.实验表明,通过DF纳米银抗菌整理,面料的抗菌性能显著提高,且具有优良的抗静电性能,整理对面料原有的透气透湿性、回潮率影响较小.%The article mainly talked about the nanometer silver antibacterial finishing to the common dose-fitting fabric of silk, cotton, wool or chemical fiber. Testing content included: nanometer silver antibacterial finishing to the fabric which has been vaccinated or not, and testing the wear behavior changes before and after treating. The testing indexes are antimicrobial property and antibacterial durative of the treated fabrics and the changes of the other wear behavior. The results showed the fabric's antibacterial capability is improved notably through DF nanometer silver antibacterial finishing, and the fabric has good antistatic capability. At the same time the finishing has little influence on costume's air and moisture penetration, moisture regain.

  7. The study of property and damage mechanism about fretting corrosion of aluminum alloy%LY12铝合金微动腐蚀特性及损伤机制研究

    Institute of Scientific and Technical Information of China (English)

    徐丽; 陈跃良; 于向财; 胡建军

    2011-01-01

    微动广泛存在于航空航天等各种机械构件中,加速构件接触表面及表层裂纹的萌生与扩展.由于海军飞机服役环境的复杂性,铝合金构件腐蚀相当严重,因此了解铝合金微动腐蚀规律具有极其重要的作用,有助于减少微动腐蚀,为老龄飞机的维护提供更多技术指导.结合微动损伤理论分析了铝合金在大气和盐水中的微动特性,总结了微动磨损过程主要的损伤机制.%Fretting usually occurs in the mechanical components of aeronautics and astronautics, and also accelerates expansion of cracks about the surface of structures. Because of the complexity of the surrounding of aircrafts, the corrosion of aluminum alloy structures is great serious. Therefore, it is very important to understand the discipline of fretting corrosion about aluminum alloy, which may help to reduce fretting corrosion and offer more technology in helping of maintenance about older airplane. In this paper, we analyze the property of fretting corrosion about aluminum alloy in atmosphere or in saline condition with fretting damage theory, and summarize the main damage mechanism of fretting wear.

  8. Assessment of wear facets produced by the ACTA wear machine

    DEFF Research Database (Denmark)

    Benetti, Ana R; Larsen, Liselotte; Dowling, Adam H

    2016-01-01

    OBJECTIVE: To investigate the use of a three-dimensional (3D) digital scanning method in determining the accuracy of the wear performance parameters of resin-based composites (RBCs) determined using a two-dimensional (2D) analogue methodology following in-vitro testing in an Academisch Centrum...... an assessment of the potential of the experimental RBC formulations for clinical usage. CONCLUSION: The 3D technique allowed for the assessment of mean maximum wear depth and mean total volumetric wear which enables tribological analyses of the wear facet and therefore the wear mechanisms operative. Employing...... profilers is useful when screening potential new RBC formulations for the restoration of posterior dentition....

  9. Dry sliding wear behavior of stir cast AA6061-T6/AlNp composite%搅拌铸造AA6061-T6/AlNp复合材料的干滑动磨损行为

    Institute of Scientific and Technical Information of China (English)

    B. ASHOK KUMAR; N. MURUGAN; I. DINAHARAN

    2014-01-01

    以 AA6061为基体、AlN 颗粒为增强体,采用搅拌铸造工艺得到 AA6061-T6/AlNp复合材料,研究了AA6061-T6/AlNp复合材料的干滑动磨损行为。开发回归模型来预测复合材料的磨损率。采用四因素、五水平的正交实验进行优化。实验因素包括滑动速度、滑动距离、荷载、增强体 AlN 颗粒的质量分数。采用 SYSTAT 12软件和统计工具,如方差分析(方差分析)和 t 实验,验证回归模型。结果表明,开发的回归模型可以有效预测复合材料的磨损率,置信度达95%。采用回归模型,并依据磨损表面形貌分析,预测实验因素对 AA6061-T6/AlNp复合材料磨损率的影响。回归模型预测结果表明,复合材料的磨损率随着增强体AlN质量分数的增加而降低,随着滑动速度、滑动距离、荷载的增加而增加。%The dry sliding wear behavior of AA6061 matrix composite reinforced with aluminium nitride particles (AlN) produced by stir casting process was investigated. A regression model was developed to predict the wear rate of the prepared composite. A four-factor, five-level central composite rotatable design matrix was used to minimize the number of experimental runs. The factors considered in this study were sliding velocity, sliding distance, normal load and mass fraction of AlN reinforcement in the matrix. The developed regression model was validated by statistical software SYSTAT 12 and statistical tools such as analysis of variance (ANOVA) and student’s t test. It was found that the developed regression model could be effectively used to predict the wear rate at 95% confidence level. The influence of these factors on wear rate of AA6061/AlNp composite was analyzed using the developed regression model and predicted trends were discussed with the aid of worn surface morphologies. The regression model indicated that the wear rate of cast AA6061/AlNp composite decreased with an increase in the mass fraction

  10. Alternating-laser excitation : single-molecule FRET and beyond

    NARCIS (Netherlands)

    Hohlbein, Johannes; Craggs, Timothy D.; Cordes, Thorben

    2014-01-01

    The alternating-laser excitation (ALEX) scheme continues to expand the possibilities of fluorescence-based assays to study biological entities and interactions. Especially the combination of ALEX and single-molecule Forster Resonance Energy Transfer (smFRET) has been very successful as ALEX enables

  11. Application of FRET probes in the analysis of neuronal plasticity

    Directory of Open Access Journals (Sweden)

    Yoshibumi eUeda

    2013-10-01

    Full Text Available Breakthroughs in imaging techniques and optical probes in recent years have revolutionized the field of life sciences in ways that traditional methods could never match. The spatial and temporal regulation of molecular events can now be studied with great precision. There have been several key discoveries that have made this possible. Since GFP was cloned in 1992, it has become the dominant tracer of proteins in living cells. Then the evolution of color variants of GFP opened the door to the application of Förster resonance energy transfer (FRET, which is now widely recognized as a powerful tool to study complicated signal transduction events and interactions between molecules. Employment of fluorescent lifetime imaging microscopy (FLIM allows the precise detection of FRET in small subcellular structures such as dendritic spines. In this review, we provide an overview of the basic and practical aspects of FRET imaging and discuss how different FRET probes have revealed insights into the molecular mechanisms of synaptic plasticity and enabled visualization of neuronal network activity both in vitro and in vivo.

  12. Plant-based FRET biosensor discriminates enviornmental zinc levels

    Science.gov (United States)

    Heavy metal accumulation in the environment poses great risks to flora and fauna. However, monitoring sites prone to accumulation poses scale and economic challenges. In this study, we present and test a method for monitoring these sites using fluorescent resonance energy transfer (FRET) change in r...

  13. Uncovering Aberrant Mutant PKA Function with Flow Cytometric FRET

    Directory of Open Access Journals (Sweden)

    Shin-Rong Lee

    2016-03-01

    Full Text Available Biology has been revolutionized by tools that allow the detection and characterization of protein-protein interactions (PPIs. Förster resonance energy transfer (FRET-based methods have become particularly attractive as they allow quantitative studies of PPIs within the convenient and relevant context of living cells. We describe here an approach that allows the rapid construction of live-cell FRET-based binding curves using a commercially available flow cytometer. We illustrate a simple method for absolutely calibrating the cytometer, validating our binding assay against the gold standard isothermal calorimetry (ITC, and using flow cytometric FRET to uncover the structural and functional effects of the Cushing-syndrome-causing mutation (L206R on PKA’s catalytic subunit. We discover that this mutation not only differentially affects PKAcat’s binding to its multiple partners but also impacts its rate of catalysis. These findings improve our mechanistic understanding of this disease-causing mutation, while illustrating the simplicity, general applicability, and power of flow cytometric FRET.

  14. Wear Resistance and Wear Mechanism of a Hot Dip Aluminized Steel in Sliding Wear Test

    Science.gov (United States)

    Xue, Zhiyong; Hao, Xiaoyang; Huang, Yao; Gu, Lingyun; Ren, Yu; Zheng, Ruipeng

    2016-12-01

    Sliding wear experiments were conducted on a hot dip aluminized steel to investigate its wear resistance and wear mechanism. The wear tests were also carried out on a hot dip galvanized steel and the base material (steel Q345) as a comparison. Results show that the wear resistance and hardness of the hot dip aluminized steel are significantly higher than that of the hot dip galvanized steel and the steel Q345 at room temperature. The better wear resistance of the hot dip aluminized steel attributes mainly to the formation of a transition layer containing abundant Fe-Al intermetallic compounds and the transformation of wear-resisting oxides during the friction process. The main phase in the transition layer is Fe2Al5. The thickness of the transition layer is about 90-120 μm. When the wear load increases from 3 N to 19 N, the wear type of the aluminized layer transform from adhesive wear (3 N) into abrasive wear (7 N) and finally into slight wear mixed with oxidation (higher than 11 N).

  15. Color control through FRET efficiency modulation using CDI (Conference Presentation)

    Science.gov (United States)

    Wolowelsky, Karni; Guyes, Eric; Rubin, Shimon; Suss, Matthew; Bercovici, Moran; Rotschild, Carmel

    2017-02-01

    Although much progress was made in light emitting devices, the ability to electrically control their spectral emission remains limited. We will present a novel approach and experimental results for dynamic color control, by electrically modulating the non-radiative Forster resonance energy transfer (FRET) efficiency between donor and acceptor dyes in a solution. FRET efficiency depends on the 6th power of the distance between donor and acceptor dye molecules, and thus, it is sensitive to variations in acceptor's concentration. Controlled acceptor concentrations could be achieved by attracting or repelling ionic dyes from the electrodes using a capacitive deionization (CDI) cell, with high surface area porous electrodes. This approach to dynamic color control may open new directions in 100% fill-factor displays, and can be expanded to energy saving applications such as controlling building's external wall emissivity. We studied the modulation of a single dye emission using a CDI cell with negatively charged Fluorescein Sodium Salt in aquatic solution. Photoluminescence was measured along few charging-discharging CDI cycles and showed the ability to control extensive optical response through CDI. We experimented with two types of FRET-pair dyes: a) anion-cation, where the acceptor and the donor ions are oppositely charged, and b) zwitterion and ion, where the donor is neutral. We found that electrical control on FRET in aquatic solution is weak, due to hydrophobic attractive interaction between the acceptor and the donor. In order to avoid this effect, we are experimenting FRET control in organic solvents. These results will be presented in the talk.

  16. TIRE WEAR MODELING

    Directory of Open Access Journals (Sweden)

    Rosen IVANOV

    2016-09-01

    Full Text Available On the basis of a known relationship, an enhanced model for specific tire wear per kilometer has been developed. It is appropriate for practical use - for evaluation of the influence of different factors. Two types of experiments have been carried out with a testing device - one without sideslip, but with a known longitudinal slip, and the other one with the same longitudinal slip but also with a known sideslip. As a result, the coefficients of the proportion of the developed model have been evaluated. After the model validation, an analytical investigation concerning the influence of tire pressure, sideslip and longitudinal slip on the tire wear has been carried out. The results are presented graphically.

  17. Single-Molecule Pull-down FRET (SiMPull-FRET) to dissect the mechanisms of biomolecular machines

    Science.gov (United States)

    Kahlscheuer, Matthew L.; Widom, Julia; Walter, Nils G.

    2016-01-01

    Spliceosomes are multi-megadalton RNA-protein complexes responsible for the faithful removal of non-coding segments (introns) from pre-messenger RNAs (pre-mRNAs), a process critical for the maturation of eukaryotic mRNAs for subsequent translation by the ribosome. Both the spliceosome and ribosome, as well as many other RNA and DNA processing machineries, contain central RNA components that endow biomolecular complexes with precise, sequence-specific nucleic acid recognition and versatile structural dynamics. Single molecule fluorescence (or Förster) resonance energy transfer (smFRET) microscopy is a powerful tool for the study of local and global conformational changes of both simple and complex biomolecular systems involving RNA. The integration of biochemical tools such as immunoprecipitation with advanced methods in smFRET microscopy and data analysis has opened up entirely new avenues towards studying the mechanisms of biomolecular machines isolated directly from complex biological specimens such as cell extracts. Here we detail the general steps for using prism-based total internal reflection fluorescence (TIRF) microscopy in exemplary single molecule pull-down FRET (SiMPull-FRET) studies of the yeast spliceosome and discuss the broad application potential of this technique. PMID:26068753

  18. 不同工况下轮轨材料间的摩擦磨损行为%Friction and Wear Behavior of Wheel/Rail Materials under Different Working Conditions

    Institute of Scientific and Technical Information of China (English)

    郭静; 王文健; 刘启跃; 周仲荣

    2013-01-01

    The rolling friction and wear behavior of wheel/rail materials was studied using a MMS-2A testing apparatus under dry, water and sanding conditions. Furthermore, the damage of wheel/rail samples was analyzed. The results show that the water would decrease rolling friction coefficient and wear volume of wheel/rail materials. Sanding could increase rolling friction coefficient and wear quantity of wheel/rail materials under water condition, and worsen the damage of the wheel/rail surface. The dry friction after sanding could make rolling friction coefficient come to the normal level in dry conditioa With the conditions changes from water to dry and water sanding, the surface damage of wheel material transformed from concave-convex roughness with slight delamination to serious spalling damage, and the delamination damage was dominant for the rail material. However, the spalling damage of rail material was slighter than that of wheel specimen.%在MMS-2A型滚动摩擦试验机上研究了干态、水态和水砂态三种工况下轮轨材料间的摩擦磨损行为,分析了轮轨试样表面的损伤情况.结果表明:相比于干态,水会使轮轨材料间的摩擦因数、磨损量明显下降;水介质中撒砂可增加轮轨材料间的滚动摩擦因数和磨损量,且加重了轮轨表面的损伤,水砂态试验中的干摩擦会使摩擦因数恢复到干态下的正常水平;随水态、干态到水砂态工况的变化,车轮试样表面从粗糙凸起并伴有轻微剥落向严重剥落损伤转变,钢轨材料的表面损伤主要表现为片层状剥离并伴有剥落现象,但较车轮材料的剥落损伤程度轻.

  19. 流变铸造不同铁含量过共晶Al-Si合金在干摩擦条件下的磨损行为%Dry sliding wear behavior of rheocast hypereutectic Al-Si alloys with different Fe contents

    Institute of Scientific and Technical Information of China (English)

    林冲; 吴树森; 吕书林; 曾劲彪; 安萍

    2016-01-01

    The effect of iron content on wear behavior of hypereutectic Al−17Si−2Cu−1Ni alloy produced by rheocasting process was investigated. The dry sliding wear tests were carried out with a pin-on-disk wear tester. The results show that the wear rate of the rheocast alloy is lower than that of the alloy produced by conventional casting process under the same applied load. The fine particle-likeδ-Al4(Fe,Mn)Si2 and polygonalα-Al15(Fe,Mn)3Si2 phases help to improve the wear resistance of rheocast alloys. As the volume fraction of fine Fe-bearing compounds increases, the wear rate of the rheocast alloy decreases. Moreover, the wear rate of rheocast alloy increases with the increase of applied load from 50 to 200 N. For the rheocast alloy with 3% Fe, oxidation wear is the main mechanism at low applied load (50 N). At higher applied loads, a combination of delamination and oxidation wear is the dominant wear mechanism.%研究铁含量对流变铸造过共晶Al−17Si−2Cu−1Ni合金在干摩擦条件下磨损行为的影响。磨损测试是在销−盘式摩擦磨损试验机上进行的。结果表明,在同等载荷下,流变铸造合金试样比传统重力金属型铸造试样的磨损率小。细小颗粒状δ-Al4(Fe,Mn)Si2相和多边形状α-Al15(Fe,Mn)3Si2相有助于提高流变铸造合金的耐磨性。随着细小富铁相体积分数的增加,流变铸造合金试样的磨损率减小。此外,随着载荷从50增大至200 N,流变铸造合金试样的磨损率增大。对于含3% Fe的流变铸造合金,在低载荷(50 N)时,磨损机制以氧化磨损为主;在高载荷时,磨损机制以氧化磨损和剥层磨损的联合作用为主。

  20. Engine oil wear resistance

    Directory of Open Access Journals (Sweden)

    A.N. Farhanah

    2015-03-01

    Full Text Available Lubricants play a vital role in an internal combustion engine to lubricate parts and help to protect and prolong the engine life. Lubricant also will help to reduce wear by creating lubricating film between the moving parts hence reduce metal-to-metal contacts. Engine oil from three different manufacturers with the same SAE viscosity grade available in market does not mean it will have the same lubricity for an engine. In this study, commercial mineral lubrication oil (SAE 10W-30 from three manufacturers was investigated to compare the lubrication performance at three different temperatures (40˚C, 70˚C and 100˚C in 60 minutes time duration by using four ball wear tester. The speed will be varied from 1000 rpm to 2500 rpm. Results show that all three lubricants have different lubricity performance; the smaller the wear scar, the better the lubricant since the lubricant can protect the moving surfaces from direct metal-to-metal contact occur.

  1. Evaluation and Description of Friction between an Electro-Deposited Coating and a Ceramic Ball under Fretting Condition

    Directory of Open Access Journals (Sweden)

    Kyungmok Kim

    2015-07-01

    Full Text Available This article describes fretting behavior of zirconia and silicon nitride balls on an electro-deposited coating. Fretting tests are performed using a ball-on-flat configuration. The evolution of the kinetic friction coefficient is determined, along with slip ratio. Experimental results show that the steady-state friction coefficient between ceramic balls (Si3N4 and ZrO2 and an electro-deposited coating is about 0.06, lower than the value between AISI 52100 ball and the coating. After a steady-state sliding, the transition of the friction coefficient is varied with a ball. The friction coefficient for ZrO2 balls became a critical value after higher fretting cycles than those for Si3N4 and AISI 52100 balls. In addition, it is identified that two parameters can describe the transition of the friction coefficient. Finally, the evolution of the friction coefficient is expressed as an exponential or a power-law form.

  2. Large-eddy simulations of turbulent flow for grid-to-rod fretting in nuclear reactors

    CERN Document Server

    Bakosi, J; Lowrie, R B; Pritchett-Sheats, L A; Nourgaliev, R R

    2013-01-01

    The grid-to-rod fretting (GTRF) problem in pressurized water reactors is a flow-induced vibration problem that results in wear and failure of the fuel rods in nuclear assemblies. In order to understand the fluid dynamics of GTRF and to build an archival database of turbulence statistics for various configurations, implicit large-eddy simulations of time-dependent single-phase turbulent flow have been performed in 3x3 and 5x5 rod bundles with a single grid spacer. To assess the computational mesh and resolution requirements, a method for quantitative assessment of unstructured meshes with no-slip walls is described. The calculations have been carried out using Hydra-TH, a thermal-hydraulics code developed at Los Alamos for the Consortium for Advanced Simulation of Light water reactors, a United States Department of Energy Innovation Hub. Hydra-TH uses a second-order implicit incremental projection method to solve the single-phase incompressible Navier-Stokes equations. The simulations explicitly resolve the la...

  3. Wear resistance of TiAlSiN thin coatings.

    Science.gov (United States)

    Silva, F J G; Martinho, R P; Alexandre, R J D; Baptista, A P M

    2012-12-01

    In the last decades TiAIN coatings deposited by PVD techniques have been extensively investigated but, nowadays, their potential development for tribological applications is relatively low. However, new coatings are emerging based on them, trying to improve wear behavior. TiAlSiN thin coatings are now investigated, analyzing if Si introduction increases the wear resistance of PVD films. Attending to the application, several wear test configurations has been recently used by some researchers. In this work, TiAISiN thin coatings were produced by PVD Unbalanced Magnetron Sputtering technique and they were conveniently characterized using Scanning Electron Microscopy (SEM) provided with Energy Dispersive Spectroscopy (EDS), Atomic Force Microscopy (AFM), Electron Probe Micro-Analyzer (EPMA), Micro Hardness (MH) and Scratch Test Analysis. Properties as morphology, thickness, roughness, chemical composition and structure, hardness and film adhesion to the substrate were investigated. Concerning to wear characterization, two very different ways were chosen: micro-abrasion with ball-on-flat configuration and industrial non-standardized tests based on samples inserted in a feed channel of a selected plastic injection mould working with 30% (wt.) glass fiber reinforced polypropylene. TiAISiN coatings with a small amount of about 5% (wt.) Si showed a similar wear behavior when compared with TiAIN reported performances, denoting that Si addition does not improve the wear performance of the TiAIN coatings in these wear test conditions.

  4. rFRET: A comprehensive, Matlab-based program for analyzing intensity-based ratiometric microscopic FRET experiments.

    Science.gov (United States)

    Nagy, Peter; Szabó, Ágnes; Váradi, Tímea; Kovács, Tamás; Batta, Gyula; Szöllősi, János

    2016-04-01

    Fluorescence or Förster resonance energy transfer (FRET) remains one of the most widely used methods for assessing protein clustering and conformation. Although it is a method with solid physical foundations, many applications of FRET fall short of providing quantitative results due to inappropriate calibration and controls. This shortcoming is especially valid for microscopy where currently available tools have limited or no capability at all to display parameter distributions or to perform gating. Since users of multiparameter flow cytometry usually apply these tools, the absence of these features in applications developed for microscopic FRET analysis is a significant limitation. Therefore, we developed a graphical user interface-controlled Matlab application for the evaluation of ratiometric, intensity-based microscopic FRET measurements. The program can calculate all the necessary overspill and spectroscopic correction factors and the FRET efficiency and it displays the results on histograms and dot plots. Gating on plots and mask images can be used to limit the calculation to certain parts of the image. It is an important feature of the program that the calculated parameters can be determined by regression methods, maximum likelihood estimation (MLE) and from summed intensities in addition to pixel-by-pixel evaluation. The confidence interval of calculated parameters can be estimated using parameter simulations if the approximate average number of detected photons is known. The program is not only user-friendly, but it provides rich output, it gives the user freedom to choose from different calculation modes and it gives insight into the reliability and distribution of the calculated parameters. © 2016 International Society for Advancement of Cytometry.

  5. Pure mechanical wear loss measurement in corrosive wear

    Indian Academy of Sciences (India)

    Yanliang Huang; Xiaoxia Jiang; Sizuo Li

    2000-12-01

    The method for the measurement of the pure mechanical wear loss for 321 stainless steel, 1045 steel and pure iron in the study of the synergy between corrosion and wear was studied. The methods studied included the measurement in distilled water, by cathodic protection and by adding inhibitor KI, and all were compared with the wear loss in air. The experiment showed that the pure mechanical wear losses and friction coefficients obtained by the three methods were close to each other and can be used to calculate the various wear components in the study of the interaction of corrosion and wear, but the measurements in distilled water for pure iron and 1045 steel are not recommended due to their corrosion.

  6. Effect of heat treatment on the wear and corrosion behaviors of a gray cast iron coated with a COLMONOY 88 alloy deposited by high velocity oxygen fuel (HVOF thermal spray

    Directory of Open Access Journals (Sweden)

    A. Öz

    2013-07-01

    Full Text Available The present work has been conducted in order to determine the influence of heat treatment on the wear and corrosion behaviours of a gray cast iron substrate coated with a Ni base coating deposited by HVOF thermal spray. The wear resistance of the coatings was obtained using a reciprocating wear tester by rubbing a 10 mm diameter steel ball on the coatings at normal atmospheric conditions. Corrosion tests were performed using potentiodynamic polarization measurements in a 3,5 % NaCl solution. It was observed that the corrosion and wear resistance of the coatings increased along with the reduction of porosity and roughness by the heat treatment.

  7. Time-gated FRET nanoassemblies for rapid and sensitive intra- and extracellular fluorescence imaging.

    Science.gov (United States)

    Afsari, Hamid Samareh; Cardoso Dos Santos, Marcelina; Lindén, Stina; Chen, Ting; Qiu, Xue; van Bergen En Henegouwen, Paul M P; Jennings, Travis L; Susumu, Kimihiro; Medintz, Igor L; Hildebrandt, Niko; Miller, Lawrence W

    2016-06-01

    Time-gated Förster resonance energy transfer (FRET) using the unique material combination of long-lifetime terbium complexes (Tb) and semiconductor quantum dots (QDs) provides many advantages for highly sensitive and multiplexed biosensing. Although time-gated detection can efficiently suppress sample autofluorescence and background fluorescence from directly excited FRET acceptors, Tb-to-QD FRET has rarely been exploited for biomolecular imaging. We demonstrate Tb-to-QD time-gated FRET nanoassemblies that can be applied for intra- and extracellular imaging. Immunostaining of different epitopes of the epidermal growth factor receptor (EGFR) with Tb- and QD-conjugated antibodies and nanobodies allowed for efficient Tb-to-QD FRET on A431 cell membranes. The broad usability of Tb-to-QD FRET was further demonstrated by intracellular Tb-to-QD FRET and Tb-to-QD-to-dye FRET using microinjection as well as cell-penetrating peptide-mediated endocytosis with HeLa cells. Effective brightness enhancement by FRET from several Tb to the same QD, the use of low nanomolar concentrations, and the quick and sensitive detection void of FRET acceptor background fluorescence are important advantages for advanced intra- and extracellular imaging of biomolecular interactions.

  8. Effect of the microhardness difference between base metal and bionic coupling unit on wear resistance of gray cast iron

    Science.gov (United States)

    Pang, Zuobo; Zhou, Hong; Chang, Fang; Zhang, Peng; Cong, Dalong; Meng, Chao; Wang, Chuanwei; Ren, Luquan

    2015-12-01

    In order to improve the wear resistance of gray cast iron guide rail, the samples with different microhardness difference between bionic coupling units and base metal were manufactured by laser surface remelting. Wear behavior of gray cast iron with bionic coupling units has been studied under dry sliding condition at room temperature using a homemade liner reciprocating wear testing machine. The wear resistance was evaluated by means of weight loss measurement and wear morphology. The results indicated that when the microhardness difference is 561 HV0.2, the wear resistance of sample is the best.

  9. Optimization of pulsed DC PACVD parameters: Toward reducing wear rate of the DLC films

    Science.gov (United States)

    Ebrahimi, Mansoureh; Mahboubi, Farzad; Naimi-Jamal, M. Reza

    2016-12-01

    The effect of pulsed direct current (DC) plasma-assisted chemical vapor deposition (PACVD) parameters such as temperature, duty cycle, hydrogen flow, and argon/CH4 flow ratio on the wear behavior and wear durability of the diamond-like carbon (DLC) films was studied by using response surface methodology (RSM). DLC films were deposited on nitrocarburized AISI 4140 steel. Wear rate and wear durability of the DLC films were examined with the pin-on-disk method. Field emission scanning electron microscopy, Raman spectroscopy, and nanoindentation techniques were used for studying wear mechanisms, chemical structure, and hardness of the DLC films. RSM results show that duty cycle is one of the important parameters that affect the wear rate of the DLC samples. The wear rate of the samples deposited with a duty cycle of >75% decreases with an increase in the argon/CH4 ratio. In contrast, for a duty cycle of <65%, the wear rate increases with an increase in the argon/CH4 ratio. The wear durability of the DLC samples increases with an increase in the duty cycle, hydrogen flow, and argon/CH4 flow ratio at the deposition temperature between 85 °C and 110 °C. Oxidation, fatigue, abrasive wear, and graphitization are the wear mechanisms observed on the wear scar of the DLC samples deposited with the optimum deposition conditions.

  10. Detecting stoichiometry of macromolecular complexes in live cells using FRET

    Science.gov (United States)

    Ben-Johny, Manu; Yue, Daniel N.; Yue, David T.

    2016-01-01

    The stoichiometry of macromolecular interactions is fundamental to cellular signalling yet challenging to detect from living cells. Fluorescence resonance energy transfer (FRET) is a powerful phenomenon for characterizing close-range interactions whereby a donor fluorophore transfers energy to a closely juxtaposed acceptor. Recognizing that FRET measured from the acceptor's perspective reports a related but distinct quantity versus the donor, we utilize the ratiometric comparison of the two to obtain the stoichiometry of a complex. Applying this principle to the long-standing controversy of calmodulin binding to ion channels, we find a surprising Ca2+-induced switch in calmodulin stoichiometry with Ca2+ channels—one calmodulin binds at basal cytosolic Ca2+ levels while two calmodulins interact following Ca2+ elevation. This feature is curiously absent for the related Na channels, also potently regulated by calmodulin. Overall, our assay adds to a burgeoning toolkit to pursue quantitative biochemistry of dynamic signalling complexes in living cells. PMID:27922011

  11. NIR FRET Fluorophores for Use as an Implantable Glucose Biosensor

    Directory of Open Access Journals (Sweden)

    Majed DWEIK

    2008-12-01

    Full Text Available Development of an in vivo optical sensor requires the utilization of Near Infra Red (NIR fluorophores due to their ability to operate within the biological tissue window. Alexa Fluor 750 (AF750 and Alexa Fluor 680 (AF680 were examined as potential NIR fluorophores for an in vivo fluorescence resonance energy transfer (FRET glucose biosensor. AF680 and AF750 found to be a FRET pair and percent energy transfer was calculated. Next, the tested dye pair was utilized in a competitive binding assay in order to detect glucose. Concanavalin A (Con A and dextran have binding affinity, but in the presence of glucose, glucose displaces dextran due to its higher affinity to Con A than dextran. Finally, the percent signal transfer through porcine skin was examined. The results showed with approximately 4.0 mm porcine skin thickness, 1.98 % of the fluorescence was transmitted and captured by the detector.

  12. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  13. Wear of polymers and composites

    CERN Document Server

    Abdelbary, Ahmed

    2015-01-01

    In the field of tribology, the wear behaviour of polymers and composite materials is considered a highly non-linear phenomenon. Wear of Polymers and Composites introduces fundamentals of polymers and composites tribology. The book suggests a new approach to explore the effect of applied load and surface defects on the fatigue wear behaviour of polymers, using a new tribometer and thorough experiments. It discusses effects of surface cracks, under different static and cyclic loading parameters on wear, and presents an intelligent algorithm, in the form of a neural network, to map the relations

  14. In vitro ageing and wear behaviour of ceria stabilized zirconia toughened alumina (CSZ-TA) bio-ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Ajoy Kumar; Jena, Usha Rani; Biswas, Koushik, E-mail: k_biswas@metal.iitkgp.ernet.in

    2014-08-01

    15–25 wt% zirconia (stabilized with 14 mol% ceria) toughened alumina was synthesized by co-precipitation technique. The synthesized powders were calcined at different temperatures, compacted and conventionally sintered following two steps sintering process. Uniformly distributed submicron sized grains with Vickers' hardness value up to 1730±6HV20 were achieved after conventional sintering. In order to assess the ageing behaviour, samples were hydrothermally treated (in vitro) at 134 °C under 0.2 MPa in presence of simulated body fluid. Rietveld refinement of the X-ray diffraction patterns was carried out to estimate the phase content after calcination, sintering and after different stages of hydrothermal treatment. No significant phase change (only ∼3%) was observed even after 100 h of hydrothermal treatment. Very few bulged grains (resulted from the tetragonal to monoclinic phase transformation) on the surface and slight decrease in hardness value were observed after hydrothermal treatment. Fretting wear in dry condition was carried out taking ball on flat geometry for 10{sup 5} cycles at different loads before and after hydrothermal treatment. Wear volumes were directly estimated from the surface scanning of the wear scar using profilometer. Transition of wear and its related mechanisms at different loads along with the effect of ageing on wear were discussed. - Highlights: • Ceria stabilized zirconia toughened alumina was developed. • Ageing behaviour of developed materials was studied through hydrothermal treatment. • Phase transformation during ageing was characterized through Rietveld refinement. • Only 3% phase transformation was observed even after 100 h hydrothermal treatment. • Fretting wear volume before band after hydrothermal treatment were estimated.

  15. Dual Readout BRET/FRET Sensors for Measuring Intracellular Zinc

    Science.gov (United States)

    2016-01-01

    Genetically encoded FRET-based sensor proteins have significantly contributed to our current understanding of the intracellular functions of Zn2+. However, the external excitation required for these fluorescent sensors can give rise to photobleaching and phototoxicity during long-term imaging, limits applications that suffer from autofluorescence and light scattering, and is not compatible with light-sensitive cells. For these applications, sensor proteins based on Bioluminescence Resonance Energy Transfer (BRET) would provide an attractive alternative. In this work, we used the bright and stable luciferase NanoLuc to create the first genetically encoded BRET sensors for measuring intracellular Zn2+. Using a new sensor approach, the NanoLuc domain was fused to the Cerulean donor domain of two previously developed FRET sensors, eCALWY and eZinCh-2. In addition to preserving the excellent Zn2+ affinity and specificity of their predecessors, these newly developed sensors enable both BRET- and FRET-based detection. While the dynamic range of the BRET signal for the eCALWY-based BLCALWY-1 sensor was limited by the presence of two competing BRET pathways, BRET/FRET sensors based on the eZinCh-2 scaffold (BLZinCh-1 and -2) yielded robust 25–30% changes in BRET ratio. In addition, introduction of a chromophore-silencing mutation resulted in a BRET-only sensor (BLZinCh-3) with increased BRET response (50%) and an unexpected 10-fold increase in Zn2+ affinity. The combination of robust ratiometric response, physiologically relevant Zn2+ affinities, and stable and bright luminescence signal offered by the BLZinCh sensors allowed monitoring of intracellular Zn2+ in plate-based assays as well as intracellular BRET-based imaging in single living cells in real time. PMID:27547982

  16. Fretting corrosion in power contacts: Electrical and thermal analysis

    OpenAIRE

    El Mossouess, S; Benjemâa, N; Carvou, E; El Abdi, R; Benmamas, L; Doublet, L

    2014-01-01

    International audience; -Fretting corrosion phenomenon is known as the main cause of contact resistance increasing in signal contact. But for power connectors this undesirable phenomenon in embarked systems is more complex because high current induces high voltages and subsequent Joule overheating can be expected during vibration. Our study deals with contact similar of power connectors ones submitted to vibration am-plitudes up to 25 micrometres at frequencies of a few 10Hz under a current r...

  17. Distinguishing the cross-beta spine arrangements in amyloid fibrils using FRET analysis.

    Science.gov (United States)

    Deng, Wei; Cao, Aoneng; Lai, Luhua

    2008-06-01

    The recently published microcrystal structures of amyloid fibrils from small peptides greatly enhanced our understanding of the atomic-level structure of the amyloid fibril. However, only a few amyloid fibrils can form microcrystals. The dansyl-tryptophan fluorescence resonance energy transfer (FRET) pair was shown to be able to detect the inter-peptide arrangement of the Transthyretin (105-115) amyloid fibril. In this study, we combined the known microcrystal structures with the corresponding FRET efficiencies to build a model for amyloid fibril structure classification. We found that fibrils with an antiparallel structural arrangement gave the largest FRET signal, those with a parallel arrangement gave the lowest FRET signal, and those with a mixed arrangement gave a moderate FRET signal. This confirms that the amyloid fibril structure patterns can be classified based on the FRET efficiency.

  18. Rise-Time of FRET-Acceptor Fluorescence Tracks Protein Folding

    Science.gov (United States)

    Lindhoud, Simon; Westphal, Adrie H.; van Mierlo, Carlo P. M.; Visser, Antonie J. W. G.; Borst, Jan Willem

    2014-01-01

    Uniform labeling of proteins with fluorescent donor and acceptor dyes with an equimolar ratio is paramount for accurate determination of Förster resonance energy transfer (FRET) efficiencies. In practice, however, the labeled protein population contains donor-labeled molecules that have no corresponding acceptor. These FRET-inactive donors contaminate the donor fluorescence signal, which leads to underestimation of FRET efficiencies in conventional fluorescence intensity and lifetime-based FRET experiments. Such contamination is avoided if FRET efficiencies are extracted from the rise time of acceptor fluorescence upon donor excitation. The reciprocal value of the rise time of acceptor fluorescence is equal to the decay rate of the FRET-active donor fluorescence. Here, we have determined rise times of sensitized acceptor fluorescence to study the folding of double-labeled apoflavodoxin molecules and show that this approach tracks the characteristics of apoflavodoxinʼs complex folding pathway. PMID:25535076

  19. pyFRET: A Python Library for Single Molecule Fluorescence Data Analysis

    OpenAIRE

    Murphy, Rebecca R.; Jackson, Sophie E.; Klenerman, David

    2014-01-01

    Single molecule F\\"orster resonance energy transfer (smFRET) is a powerful experimental technique for studying the properties of individual biological molecules in solution. However, as adoption of smFRET techniques becomes more widespread, the lack of available software, whether open source or commercial, for data analysis, is becoming a significant issue. Here, we present pyFRET, an open source Python package for the analysis of data from single-molecule fluorescence experiments from freely...

  20. Considerations for sensitivity analysis, uncertainty quantification, and data assimilation for grid-to-rod fretting

    Energy Technology Data Exchange (ETDEWEB)

    Michael Pernice

    2012-10-01

    Grid-to-rod fretting is the leading cause of fuel failures in pressurized water reactors, and is one of the challenge problems being addressed by the Consortium for Advanced Simulation of Light Water Reactors to guide its efforts to develop a virtual reactor environment. Prior and current efforts in modeling and simulation of grid-to-rod fretting are discussed. Sources of uncertainty in grid-to-rod fretting are also described.

  1. Rise-time of FRET-acceptor fluorescence tracks protein folding

    OpenAIRE

    Simon Lindhoud; Adrie H. Westphal; van Mierlo, Carlo P. M.; Visser, Antonie J. W. G.; Jan Willem Borst

    2014-01-01

    Uniform labeling of proteins with fluorescent donor and acceptor dyes with an equimolar ratio is paramount for accurate determination of Förster resonance energy transfer (FRET) efficiencies. In practice, however, the labeled protein population contains donor-labeled molecules that have no corresponding acceptor. These FRET-inactive donors contaminate the donor fluorescence signal, which leads to underestimation of FRET efficiencies in conventional fluorescence intensity and lifetime-based F...

  2. Friction and Wear Characteristics of Mg-Al Alloy Containing Rare Earths

    Institute of Scientific and Technical Information of China (English)

    祁庆琚; 刘勇兵; 杨晓红

    2003-01-01

    The influence of rare earth on the friction and wear characteristics of magnesium alloy AZ91 and AM60 were studied. The results show that the wear resistance properties of rare earth magnesium alloys are better than those of matrix alloy under the testing conditions. The anti-wear behaviour of AZ91 alloy is much better than that of AM60 alloy. In dry sliding process,magnesium alloys undergo a transition from mild wear to severe wear. The addition of rare earths refine the structure of alloys, improve the comprehensive behaviors of magnesium alloys, increase the stability of oxidation films on worn surfaces, enhance the loading ability of rare earth magnesium alloys, and delay the transition from mild wear to severe wear effectively.

  3. A Multicolor Single-Molecule FRET Approach to Study Protein Dynamics and Interactions Simultaneously.

    Science.gov (United States)

    Götz, M; Wortmann, P; Schmid, S; Hugel, T

    2016-01-01

    Single-molecule Förster resonance energy transfer (smFRET) is a versatile tool for studying biomolecules in a quantitative manner. Multiple conformations within and interactions between biomolecules can be detected and their kinetics can be determined. Thus, smFRET has become an essential tool in enzymology. Ordinary two-color smFRET experiments can provide only limited insight into the function of biological systems, which commonly consist of more than two components. A complete understanding of complex multicomponent biological systems requires correlated information on conformational rearrangements on the one hand and transient interactions with binding partners on the other. Multicolor smFRET experiments enable the direct observation of such correlated dynamics and interactions. Here we demonstrate the power and limitations of multicolor smFRET experiments including the description of a multicolor smFRET setup and data analysis. A general analytical procedure for multicolor smFRET data is presented and applied to the multicomponent heat shock protein 90 system. This allows us to identify microscopic states in transient complexes. Conformational dynamics and nucleotide binding are simultaneously detected, which is impossible using two-color smFRET. Additionally, their correlation is quantified using 3D ensemble hidden Markov analysis, in and out of equilibrium. This method is perfectly suited for protein systems that are much more sophisticated than previously studied DNA-based systems. By extending the application to biologically relevant systems, multicolor smFRET comes of age and provides a unique mechanistic insight into protein machines.

  4. A communication theoretical analysis of FRET-based mobile ad hoc molecular nanonetworks.

    Science.gov (United States)

    Kuscu, Murat; Akan, Ozgur B

    2014-09-01

    Nanonetworks refer to a group of nanosized machines with very basic operational capabilities communicating to each other in order to accomplish more complex tasks such as in-body drug delivery, or chemical defense. Realizing reliable and high-rate communication between these nanomachines is a fundamental problem for the practicality of these nanonetworks. Recently, we have proposed a molecular communication method based on Förster Resonance Energy Transfer (FRET) which is a nonradiative excited state energy transfer phenomenon observed among fluorescent molecules, i.e., fluorophores. We have modeled the FRET-based communication channel considering the fluorophores as single-molecular immobile nanomachines, and shown its reliability at high rates, and practicality at the current stage of nanotechnology. In this study, for the first time in the literature, we investigate the network of mobile nanomachines communicating through FRET. We introduce two novel mobile molecular nanonetworks: FRET-based mobile molecular sensor/actor nanonetwork (FRET-MSAN) which is a distributed system of mobile fluorophores acting as sensor or actor node; and FRET-based mobile ad hoc molecular nanonetwork (FRET-MAMNET) which consists of fluorophore-based nanotransmitter, nanoreceivers and nanorelays. We model the single message propagation based on birth-death processes with continuous time Markov chains. We evaluate the performance of FRET-MSAN and FRET-MAMNET in terms of successful transmission probability and mean extinction time of the messages, system throughput, channel capacity and achievable communication rates.

  5. Understanding and modeling Förster-type resonance energy transfer (FRET)

    CERN Document Server

    Hernández Martínez, Pedro Ludwig; Demir, Hilmi Volkan

    2017-01-01

    This Brief presents a complete study of the generalized theory of Förster-type energy transfer in nanostructures with mixed dimensionality. Here the aim is to obtain a generalized theory of FRET including a comprehensive set of analytical equations for all combinations and configurations of nanostructures and deriving generic expressions for the dimensionality involved. In this brief, the modification of FRET mechanism with respect to the nanostructure serving as the donor vs. the acceptor will be included, focusing on the rate’s distance dependency and the role of the effective dielectric function in FRET, which will be a unique, useful source for those who study and model FRET.

  6. Wear of micro end mills

    DEFF Research Database (Denmark)

    Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo

    2005-01-01

    This paper addresses the important issue of wear on micro end mills considering relevant metrological tools for its characterization and quantification. Investigation of wear on micro end mills is particularly difficult and no data are available in the literature. Small worn volumes cause large d...

  7. [Infants wearing teething necklaces].

    Science.gov (United States)

    Taillefer, A; Casasoprana, A; Cascarigny, F; Claudet, I

    2012-10-01

    Numerous infants wear teething necklaces, a quack remedy with a real risk of strangulation or aspiration of small beads. Evaluate parental perceptions and beliefs about the use of teething necklaces and analyze parental knowledge about the associated dangers. Between March and July 2011, in three different pediatric units of a tertiary children's hospital and a general hospital in Toulouse and Montauban (southwest France), voluntary parents were invited to be interviewed about their child wearing a teething necklace. The interviews were conducted following an anthropological approach: they were recorded and then fully transcribed and analyzed. Parents were informed that the conversation was recorded. During the study period, 48 children were eligible. Eleven families refused to participate, 29 parents were interviewed face to face. The children's mean age was 14 years ± 7 months, the male:female ratio was equal to 0.8 (12 boys, 15 girls). The mean age of children when necklace wearing was started was equal to 4 ± 2 months. The mean mother's age was 31 ± 5 years and 33 ± 4 years for fathers. The parents' religion was mostly Catholic (60%). Teething necklaces were mainly made of amber (n=23). Sales information about the risks associated with the necklaces was for the most part absent (92%). The most frequent positive parental perceptions were analgesic properties and a soothing remedy (73%); a birth accessory and memory (64%); an esthetic accessory (60%); a protective amulet (60%); and an alternative or additional element to other traditional therapeutics (55%). The negative parental perceptions (n=4) were an unnecessary accessory, costume jewelry, a pure commercial abuse of a popular belief, a dangerous item with a risk of strangulation, and the absence of proof of its efficacy. Although parents concede that teeth eruption is benign, they fear its related symptoms. To a natural phenomenon a natural response: they use a necklace to satisfy the analogy. The

  8. Friction and wear properties of N+ ion implanted nylon 1010

    Institute of Scientific and Technical Information of China (English)

    XIONG Dang-sheng

    2004-01-01

    The PA1010 was implanted with 450 keV N+ ions to three doses of 5× 1014 cm-2 , 2.5× 1015 cm-2 and 1.25 × 1016 cm-2. The friction and wear behaviors of the ion implanted PA1010 disks rubbing with two ceramic (ZrO2 and Si3N4) balls were studied using a pin-on-disk tribometer under dry friction. The results shows that the wear resistance of PA1010 is increased with the increasing implantation doses. The adhesion, plastic deformation and plow groove are wearing mechanisms for un-implanted PA1010, while abrasive wear for implanted PA1010.

  9. AccPbFRET: An ImageJ plugin for semi-automatic, fully corrected analysis of acceptor photobleaching FRET images

    Directory of Open Access Journals (Sweden)

    Vereb György

    2008-08-01

    Full Text Available Abstract Background The acceptor photobleaching fluorescence resonance energy transfer (FRET method is widely used for monitoring molecular interactions in cells. This method of FRET, while among those with the simplest mathematics, is robust, self-controlled and independent of fluorophore amounts and ratios. Results AccPbFRET is a user-friendly, efficient ImageJ plugin which allows fully corrected, pixel-wise calculation and detailed, ROI (region of interest-based analysis of FRET efficiencies in microscopic images. Furthermore, automatic registration and semi-automatic analysis of large image sets is provided, which are not available in any existing FRET evaluation software. Conclusion Despite of the widespread applicability of the acceptor photobleaching FRET technique, this is the first paper where all possible sources of major errors of the measurement and analysis are considered, and AccPbFRET is the only program which provides the complete suite of corrections – for registering image pairs, for unwanted photobleaching of the donor, for cross-talk of the acceptor and/or its photoproduct to the donor channel and for partial photobleaching of the acceptor. The program efficiently speeds up the analysis of large image sets even for novice users and is freely available.

  10. Fretting Damage of ACSR Conductor Enwrapped with Aluminium Armour Tape%铝包带包裹高压输电线路导线的微动损伤

    Institute of Scientific and Technical Information of China (English)

    陈国宏; 王煦; 王家庆; 刘俊建; 张涛; 汤文明

    2012-01-01

    Abstract : Fretting experirr, ent of the aluminum conductor steel reinforced (ACSR) conductor enwrapped with aluminium armour tape was carried out using a conductor fretting testing equipment made by the authors. After fretting for 2.0X 10r cycles at an amplitude of 1.0 ram, fretting damage of the external and internal A] strands and steel core strands of the conductor was investigated, and the tensile strengths of them were also measured. Moreover, the fretting damage mechanism of the enwrapped conductor was discussed. The results showed that the external A] strands were injured by the scratch of the aluminium armour tape and the abrasive wear. The wear marks of the internal A1 strands were all elliptical, partially, there were fatigue cracks under them. The steel core strands were slightly damaged, only adhesion wear and piece deprivation of the galvanized zinc layer took place. The aluminium armour tape could effectively protect the ACSR conductor, so that the internal and external A1 strands of the enwrapped conductor had higher tensile strengths than those of the unenwrapped conductor.%在自制的微动试验装置上对铝包带包裹钢芯铝绞导线(ACSR)进行微动试验研究。振幅1.0mm,2.0×107次微动循环后,研究内、外层铝股线及钢芯线的磨损状况,测定其抗拉强度,探讨铝包带包裹导线的微动损伤机制。结果表明:外层铝股线表面经受铝包带的刮擦以及磨粒磨损;内层铝股线微动磨损斑呈椭圆形,部分磨损斑下有疲劳裂纹;而钢芯线的损伤微弱,仅发生镀锌层的磨损、脱落。铝包带对导线有较好的保护作用,内外层铝股线的抗拉强度均高于未包裹导线的抗拉强度。

  11. Automated selection of regions of interest for intensity-based FRET analysis of transferrin endocytic trafficking in normal vs. cancer cells.

    Science.gov (United States)

    Talati, Ronak; Vanderpoel, Andrew; Eladdadi, Amina; Anderson, Kate; Abe, Ken; Barroso, Margarida

    2014-03-15

    The overexpression of certain membrane-bound receptors is a hallmark of cancer progression and it has been suggested to affect the organization, activation, recycling and down-regulation of receptor-ligand complexes in human cancer cells. Thus, comparing receptor trafficking pathways in normal vs. cancer cells requires the ability to image cells expressing dramatically different receptor expression levels. Here, we have presented a significant technical advance to the analysis and processing of images collected using intensity based Förster resonance energy transfer (FRET) confocal microscopy. An automated Image J macro was developed to select region of interests (ROI) based on intensity and statistical-based thresholds within cellular images with reduced FRET signal. Furthermore, SSMD (strictly standardized mean differences), a statistical signal-to-noise ratio (SNR) evaluation parameter, was used to validate the quality of FRET analysis, in particular of ROI database selection. The Image J ROI selection macro together with SSMD as an evaluation parameter of SNR levels, were used to investigate the endocytic recycling of Tfn-TFR complexes at nanometer range resolution in human normal vs. breast cancer cells expressing significantly different levels of endogenous TFR. Here, the FRET-based assay demonstrates that Tfn-TFR complexes in normal epithelial vs. breast cancer cells show a significantly different E% behavior during their endocytic recycling pathway. Since E% is a relative measure of distance, we propose that these changes in E% levels represent conformational changes in Tfn-TFR complexes during endocytic pathway. Thus, our results indicate that Tfn-TFR complexes undergo different conformational changes in normal vs. cancer cells, indicating that the organization of Tfn-TFR complexes at the nanometer range is significantly altered during the endocytic recycling pathway in cancer cells. In summary, improvements in the automated selection of FRET ROI datasets

  12. FRET and colocalization analyzer--a method to validate measurements of sensitized emission FRET acquired by confocal microscopy and available as an ImageJ Plug-in.

    Science.gov (United States)

    Hachet-Haas, Muriel; Converset, Noël; Marchal, Olivier; Matthes, Hans; Gioria, Sophie; Galzi, Jean-Luc; Lecat, Sandra

    2006-12-01

    Fluorescence resonance energy transfer (FRET) between an adequate pair of fluorophores is an indication of closer proximity than colocalization and is used by biologists to study fluorescently modified protein interactions inside cells. We present a method for visualization of FRET images acquired by confocal sensitized emission, involving excitation of the donor fluorophore and detection of the energy transfer as an emission from the acceptor fluorophore into the FRET channel. Authentic FRET signal measurements require the correction from the FRET channel of the undesired bleed-through signals (BT) resulting from both the leak-through of the donor emission and the direct acceptor emission. Our method reduces the interference of the user to a minimum by analyzing the entire image, pixel by pixel. It proposes imaging treatments and the display of control images to validate the BT calculation and the image corrections. It displays FRET images as a function of the colocalization of the two fluorescent partners. Finally, it proposes an alternative to normalization of the FRET intensities to compare FRET signal variations between samples. This method called "FRET and Colocalization Analyzer" has been implemented in a Plug-in of the freely available ImageJ software. It is particularly adapted when transient expression of the fluorescent proteins is used thereby giving very variable expression levels or when the colocalization of the two partners is varying in proportion, in amount, and in size, as a function of time. The method and program are validated using the analysis of the spatio-temporal interactions between a G-protein coupled receptor, the tachykinin NK2 receptor, and the beta-arrestin 2 as an example.

  13. Switch wear leveling

    Science.gov (United States)

    Wu, Hunter; Sealy, Kylee; Gilchrist, Aaron

    2015-09-01

    An apparatus for switch wear leveling includes a switching module that controls switching for two or more pairs of switches in a switching power converter. The switching module controls switches based on a duty cycle control technique and closes and opens each switch in a switching sequence. The pairs of switches connect to a positive and negative terminal of a DC voltage source. For a first switching sequence a first switch of a pair of switches has a higher switching power loss than a second switch of the pair of switches. The apparatus includes a switch rotation module that changes the switching sequence of the two or more pairs of switches from the first switching sequence to a second switching sequence. The second switch of a pair of switches has a higher switching power loss than the first switch of the pair of switches during the second switching sequence.

  14. Low friction wear resistant graphene films

    Science.gov (United States)

    Sumant, Anirudha V.; Berman, Diana; Erdemir, Ali

    2017-02-07

    A low friction wear surface with a coefficient of friction in the superlubric regime including graphene and nanoparticles on the wear surface is provided, and methods of producing the low friction wear surface are also provided. A long lifetime wear resistant surface including graphene exposed to hydrogen is provided, including methods of increasing the lifetime of graphene containing wear surfaces by providing hydrogen to the wear surface.

  15. Effectiveness of payment for reduced carbon monoxide levels and noncontingent payments on smoking behaviors in cocaine-abusing outpatients wearing nicotine or placebo patches.

    Science.gov (United States)

    Wiseman, Eve J; Williams, D K; McMillan, D E

    2005-05-01

    In a 2-week intervention to reduce cigarette smoking among outpatients in treatment for cocaine addiction, 20 subjects were randomly assigned to a contingent group, receiving monetary vouchers for breath samples with carbon monoxide (CO) levels of 8 ppm or less, or to a noncontingent group, receiving vouchers regardless of CO level. Subjects wore either nicotine or placebo patches in a randomized crossover design. Contingent subjects had significantly lower CO levels and met the 8 ppm target significantly more often than did noncontingent subjects; however, number of cigarettes reported smoked did not differ between groups. Use of nicotine patches resulted in CO levels significantly lower than did use of placebo patches, but levels still exceeded 8 ppm regardless of type of patch. Because contingent reward helped cocaine-dependent smokers achieve nonsmoking CO targets, behavioral antismoking interventions merit continued study in similar populations.

  16. Cutting performance and wear mechanisms of PVD coated carbide tools during dry drilling of newly produced ADI

    Science.gov (United States)

    Meena, Anil; El Mansori, Mohamed

    2016-10-01

    The austempered ductile iron (ADI) material is widely used for automotive and structural applications. However, it is considered a difficult to machine material due to its strain hardening behavior and low thermal conductivity characteristics; thus delivering higher mechanical and thermal loads at the tool-chip interface, which significantly affects the tool wear and surface quality. The paper thus overviews the cutting performance and wear behavior of different cutting tools during dry drilling of newly produced ADI material. Cutting performance was evaluated in terms of specific cutting energy, workpiece surface integrity and tool wear behavior. Tool wear behavior shows crater wear mode and workpiece adhesion. The surface alteration at the machined subsurface was confirmed from the hardness variation. Multilayer (Ti,Al,Cr)N coated tool shows improved cutting performance and wear behavior due to its enhanced tribological adaptability as compared to another PVD coating leading to the reduction in specific cutting energy by 25%.

  17. Mining the Sinorhizobium meliloti transportome to develop FRET biosensors for sugars, dicarboxylates and cyclic polyols.

    Directory of Open Access Journals (Sweden)

    Alexandre Bourdès

    Full Text Available Förster resonance energy transfer (FRET biosensors are powerful tools to detect biologically important ligands in real time. Currently FRET bisosensors are available for twenty-two compounds distributed in eight classes of chemicals (two pentoses, two hexoses, two disaccharides, four amino acids, one nucleobase, two nucleotides, six ions and three phytoestrogens. To expand the number of available FRET biosensors we used the induction profile of the Sinorhizobium meliloti transportome to systematically screen for new FRET biosensors.Two new vectors were developed for cloning genes for solute-binding proteins (SBPs between those encoding FRET partner fluorescent proteins. In addition to a vector with the widely used cyan and yellow fluorescent protein FRET partners, we developed a vector using orange (mOrange2 and red fluorescent protein (mKate2 FRET partners. From the sixty-nine SBPs tested, seven gave a detectable FRET signal change on binding substrate, resulting in biosensors for D-quinic acid, myo-inositol, L-rhamnose, L-fucose, β-diglucosides (cellobiose and gentiobiose, D-galactose and C4-dicarboxylates (malate, succinate, oxaloacetate and fumarate. To our knowledge, we describe the first two FRET biosensor constructs based on SBPs from Tripartite ATP-independent periplasmic (TRAP transport systems.FRET based on orange (mOrange2 and red fluorescent protein (mKate2 partners allows the use of longer wavelength light, enabling deeper penetration of samples at lower energy and increased resolution with reduced back-ground auto-fluorescence. The FRET biosensors described in this paper for four new classes of compounds; (i cyclic polyols, (ii L-deoxy sugars, (iii β-linked disaccharides and (iv C4-dicarboxylates could be developed to study metabolism in vivo.

  18. Tool wear mechanism in turning of novel wear-resisting aluminum bronze

    Institute of Scientific and Technical Information of China (English)

    倪东惠; 夏伟; 张大童; 郭国文; 邵明

    2003-01-01

    Tool wear and wear mechanism during the turning of a wear-resisting aluminum bronze have been stud-ied. Tool wear samples were prepared by using M2 high-speed steel and YW1 cemented carbide tools to turn a novelhigh strength, wear resisting aluminum bronze without coolant and lubricant. Adhesion of workpiece materials wasfound on tool's surface. Under the turning condition used in this study major wear mechanisms for turning aluminumbronze using M2 high-speed steel tool are diffusion wear, adhesive wear and plastic deformation and shear on thecrater. Partial melting of high-speed steel on the rake plays a role in the tool wear also. Major wear mechanisms forturning aluminum bronze using YW1 cemented carbide tool are diffusion wear, attrition wear and sliding wear. Tocontrol the machining temperature is essential to reduce tool wear.

  19. Evaluating the Relationship between FRET Changes and Distance Changes Using DNA Length and Restriction Enzyme Specificity

    Science.gov (United States)

    Pazhani, Yogitha; Horn, Abigail E.; Grado, Lizbeth; Kugel, Jennifer F.

    2016-01-01

    FRET (Fo¨rster resonance energy transfer) involves the transfer of energy from an excited donor fluorophore to an acceptor molecule in a manner that is dependent on the distance between the two. A biochemistry laboratory experiment is described that teaches students how to use FRET to evaluate distance changes in biological molecules. Students…

  20. FRET Imaging Trackable Long-Circulating Biodegradable Nanomedicines for Ovarian Cancer Therapy

    Science.gov (United States)

    2014-09-01

    Award Number: W81XWH-13-1-0160 TITLE: FRET Imaging Trackable Long-Circulating Biodegradable ...TITLE AND SUBTITLE FRET Imaging Trackable Long-Circulating Biodegradable Nanomedicines for Ovarian Cancer Therapy 5a. CONTRACT NUMBER...strategy, which permits visualizing the biodegradation of copolymer-drug conjugates at the body, tissue and cell levels in real time. The information

  1. Lateral diffusion contributes to FRET from lanthanide-tagged membrane proteins

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Tien-Hung; Wu, Guangyu; Lambert, Nevin A., E-mail: nelambert@gru.edu

    2015-08-14

    Diffusion can enhance Förster resonance energy transfer (FRET) when donors or acceptors diffuse distances that are similar to the distances separating them during the donor's excited state lifetime. Lanthanide donors remain in the excited state for milliseconds, which makes them useful for time-resolved FRET applications but also allows time for diffusion to enhance energy transfer. Here we show that diffusion dramatically enhances FRET between membrane proteins labeled with lanthanide donors. This phenomenon complicates interpretation of experiments that use long-lived donors to infer association or proximity of mobile membrane proteins, but also offers a method of monitoring diffusion in membrane domains in real time in living cells. - Highlights: • Diffusion enhances TR-FRET from membrane proteins labeled with lanthanide donors. • Diffusion-dependent FRET can overshadow FRET due to oligomerization or clustering. • FRET studies using lanthanide-tagged membrane proteins should consider diffusion. • FRET from lanthanide donors can be used to monitor membrane protein diffusion.

  2. Multifunctional Concentric FRET-Quantum Dot Probes for Tracking and Imaging of Proteolytic Activity.

    Science.gov (United States)

    Massey, Melissa; Li, Jia Jun; Algar, W Russ

    2017-01-01

    Proteolysis has many important roles in physiological regulation. It is involved in numerous cell signaling processes and the pathogenesis of many diseases, including cancers. Methods of visualizing and assaying proteolytic activity are therefore in demand. Förster resonance energy transfer (FRET) probes offer several advantages in this respect. FRET supports end-point or real-time measurements, does not require washing or separation steps, and can be implemented in various assay or imaging formats. In this chapter, we describe methodology for preparing self-assembled concentric FRET (cFRET) probes for multiplexed tracking and imaging of proteolytic activity. The cFRET probe comprises a green-emitting semiconductor quantum dot (QD) conjugated with multiple copies of two different peptide substrates for two target proteases. The peptide substrates are labeled with different fluorescent dyes, Alexa Fluor 555 and Alexa Fluor 647, and FRET occurs between the QD and both dyes, as well as between the two dyes. This design enables a single QD probe to track the activity of two proteases simultaneously. Fundamental cFRET theory is presented, and procedures for using the cFRET probe for quantitative measurement of the activity of two model proteases are given, including calibration, fluorescence plate reader or microscope imaging assays, and data analysis. Sufficient detail is provided for other researchers to adapt this method to their specific requirements and proteolytic systems of interest.

  3. Engineering of weak helper interactions for high-efficiency FRET probes.

    Science.gov (United States)

    Grünberg, Raik; Burnier, Julia V; Ferrar, Tony; Beltran-Sastre, Violeta; Stricher, François; van der Sloot, Almer M; Garcia-Olivas, Raquel; Mallabiabarrena, Arrate; Sanjuan, Xavier; Zimmermann, Timo; Serrano, Luis

    2013-10-01

    Fluorescence resonance energy transfer (FRET)-based detection of protein interactions is limited by the very narrow range of FRET-permitting distances. We show two different strategies for the rational design of weak helper interactions that co-recruit donor and acceptor fluorophores for a more robust detection of bimolecular FRET: (i) in silico design of electrostatically driven encounter complexes and (ii) fusion of tunable domain-peptide interaction modules based on WW or SH3 domains. We tested each strategy for optimization of FRET between (m)Citrine and mCherry, which do not natively interact. Both approaches yielded comparable and large increases in FRET efficiencies with little or no background. Helper-interaction modules can be fused to any pair of fluorescent proteins and could, we found, enhance FRET between mTFP1 and mCherry as well as between mTurquoise2 and mCitrine. We applied enhanced helper-interaction FRET (hiFRET) probes to study the binding between full-length H-Ras and Raf1 as well as the drug-induced interaction between Raf1 and B-Raf.

  4. Wear Performance of Cu-Alloyed Austempered Ductile Iron

    Science.gov (United States)

    Batra, Uma; Batra, Nimish; Sharma, J. D.

    2013-04-01

    An investigation was carried out to examine the influence of structural and mechanical properties on wear behavior of austempered ductile iron (ADI). Ductile iron (DI) samples were austenitized at 900 °C for 60 min and subsequently austempered for 60 min at three temperatures: 270, 330, and 380 °C. Microstructures of the as-cast DI and ADIs were characterized using optical and scanning microscopy, respectively. The structural parameters, volume fraction of austenite, carbon content of austenite, and ferrite particle size were determined using x-ray diffraction technique. Mechanical properties including Vicker's hardness, 0.2% proof strength, ultimate tensile strength, ductility, and strain hardening coefficient were determined. Wear tests were carried out under dry sliding conditions using pin-on-disk machine with a linear speed of 2.4 m/s. Normal load and sliding distance were 45 N and 1.7 × 104 m, respectively. ADI developed at higher austempering temperature has large amounts of austenite, which contribute toward improvement in the wear resistance through stress-induced martensitic transformation, and strain hardening of austenite. Wear rate was found to depend on 0.2% proof strength, ductility, austenite content, and its carbon content. Study of worn surfaces and nature of wear debris revealed that the fine ausferrite structure in ADIs undergoes oxidational wear, but the coarse ausferrite structure undergoes adhesion, delamination, and mild abrasion too.

  5. A Versatile Multiple Target Detection System Based on DNA Nano-assembled Linear FRET Arrays.

    Science.gov (United States)

    Li, Yansheng; Du, Hongwu; Wang, Wenqian; Zhang, Peixun; Xu, Liping; Wen, Yongqiang; Zhang, Xueji

    2016-05-27

    DNA molecules have been utilized both as powerful synthetic building blocks to create nanoscale architectures and as inconstant programmable templates for assembly of biosensors. In this paper, a versatile, scalable and multiplex detection system is reported based on an extending fluorescent resonance energy transfer (FRET) cascades on a linear DNA assemblies. Seven combinations of three kinds of targets are successfully detected through the changes of fluorescence spectra because of the three-steps FRET or non-FRET continuity mechanisms. This nano-assembled FRET-based nanowire is extremely significant for the development of rapid, simple and sensitive detection system. The method used here could be extended to a general platform for multiplex detection through more-step FRET process.

  6. pyFRET: A Python Library for Single Molecule Fluorescence Data Analysis

    CERN Document Server

    Murphy, Rebecca R; Klenerman, David

    2014-01-01

    Single molecule F\\"orster resonance energy transfer (smFRET) is a powerful experimental technique for studying the properties of individual biological molecules in solution. However, as adoption of smFRET techniques becomes more widespread, the lack of available software, whether open source or commercial, for data analysis, is becoming a significant issue. Here, we present pyFRET, an open source Python package for the analysis of data from single-molecule fluorescence experiments from freely diffusing biomolecules. The package provides methods for the complete analysis of a smFRET dataset, from burst selection and denoising, through data visualisation and model fitting. We provide support for both continuous excitation and alternating laser excitation (ALEX) data analysis. pyFRET is available as a package downloadable from the Python Package Index (PyPI) under the open source three-clause BSD licence, together with links to extensive documentation and tutorials, including example usage and test data. Additio...

  7. Imaging of Metabolic Status in 3D Cultures with an Improved AMPK FRET Biosensor for FLIM

    Directory of Open Access Journals (Sweden)

    George Chennell

    2016-08-01

    Full Text Available We describe an approach to non-invasively map spatiotemporal biochemical and physiological changes in 3D cell culture using Forster Resonance Energy Transfer (FRET biosensors expressed in tumour spheroids. In particular, we present an improved Adenosine Monophosphate (AMP Activated Protein Kinase (AMPK FRET biosensor, mTurquoise2 AMPK Activity Reporter (T2AMPKAR, for fluorescence lifetime imaging (FLIM readouts that we have evaluated in 2D and 3D cultures. Our results in 2D cell culture indicate that replacing the FRET donor, enhanced Cyan Fluorescent Protein (ECFP, in the original FRET biosensor, AMPK activity reporter (AMPKAR, with mTurquoise2 (mTq2FP, increases the dynamic range of the response to activation of AMPK, as demonstrated using the direct AMPK activator, 991. We demonstrated 3D FLIM of this T2AMPKAR FRET biosensor expressed in tumour spheroids using two-photon excitation.

  8. They shall wear fringes.

    Science.gov (United States)

    Sugar, M

    1999-01-01

    The multiple functions of clothes include utility, protection, rivalry, disguise, camouflage, display for seduction purposes, aggression, totemism, and status. Here the focus is on a decorative and distinctive hierarchical aspect of ancient dress, the tsitsit or fringes, whose original function is long absent, but that has endured for 3,500 years in Judaism. The beginning of their use beyond the totemic appears related to issues of changing identity from slavery to liberty, endowing noble status, exhibitionism, a symbol of identity, identification with the aggressor, a talisman, and potency. It is conceptualized that they became a symbol, or a specifier, that helped promote group cohesion in ex-slaves who were frightened, dependent, anxious, and not hopeful about their future. The tsitsit aided the development of a new identity and made all Israelites equal and noble to the observer. The durability of this symbol to the present is evident in its daily wear, as an accompaniment to daily prayers, as well as in its use as a burial shroud for males. It appears that the tsitsit have additional multiple functions. These are the promise of oral and genital satisfaction, and the pleasure of the after-life, superego warnings and control of sexual impulses, protection, survival value, and affirmation. Since they offer sublimation with acceptable gratification of instincts, the tsitsit have become ritualized and endure.

  9. Size Dependence of Nanoscale Wear of Silicon Carbide.

    Science.gov (United States)

    Tangpatjaroen, Chaiyapat; Grierson, David; Shannon, Steve; Jakes, Joseph E; Szlufarska, Izabela

    2017-01-18

    Nanoscale, single-asperity wear of single-crystal silicon carbide (sc-SiC) and nanocrystalline silicon carbide (nc-SiC) is investigated using single-crystal diamond nanoindenter tips and nanocrystalline diamond atomic force microscopy (AFM) tips under dry conditions, and the wear behavior is compared to that of single-crystal silicon with both thin and thick native oxide layers. We discovered a transition in the relative wear resistance of the SiC samples compared to that of Si as a function of contact size. With larger nanoindenter tips (tip radius ≈ 370 nm), the wear resistances of both sc-SiC and nc-SiC are higher than that of Si. This result is expected from the Archard's equation because SiC is harder than Si. However, with the smaller AFM tips (tip radius ≈ 20 nm), the wear resistances of sc-SiC and nc-SiC are lower than that of Si, despite the fact that the contact pressures are comparable to those applied with the nanoindenter tips, and the plastic zones are well-developed in both sets of wear experiments. We attribute the decrease in the relative wear resistance of SiC compared to that of Si to a transition from a wear regime dominated by the materials' resistance to plastic deformation (i.e., hardness) to a regime dominated by the materials' resistance to interfacial shear. This conclusion is supported by our AFM studies of wearless friction, which reveal that the interfacial shear strength of SiC is higher than that of Si. The contributions of surface roughness and surface chemistry to differences in interfacial shear strength are also discussed.

  10. Intelligent Detection of Drill Wear

    Science.gov (United States)

    Liu, T. I.; Chen, W. Y.; Anatharaman, K. S.

    1998-11-01

    Backpropagation neural networks (BPNs) were used for on-line detection of drill wear. The neural network consisted of three layers: input, hidden, and output. The input vector comprised drill size, feed rate, spindle speed, and eight features obtained by processing the thrust and torque signals. The output was the drill wear state which either usable or failure. Drilling experiments with various drill sizes, feed rates and spindle speeds were carried out. The learning process was performed effectively by utilising backpropagation with smoothing and an activation function slope. The on-line detection of drill wear states using BPNs achieved 100% reliability even when the drill size, feed rate and spindle speed were changed. In other words, the developed on-line drill wear detection systems have very high robustness and hence can be used in very complex production environments, such as flexible manufacturing systems.

  11. Wear behaviour of Al 261

    Directory of Open Access Journals (Sweden)

    N. Mathan Kumar

    2016-03-01

    Full Text Available Al 2618 matrix material was mixed with the Silicon Nitride (Si3N4, Aluminium Nitride (AlN and Zirconium Boride (ZrB2 reinforced particles. AMC was synthesized successfully by the stir casting method with the various X-wt.% of reinforcements (X = 0,2,4,6,8. Tribological behaviour was studied in this composite with various temperature conditions. The working conditions were Temperature (°C, Load (N, Velocity (m/s and Sliding Distances (m. Before wear testing the mechanical behaviour has been analysed. EDAX was confirmed by the matrix material composition. The Al 2618 alloy and the reinforcement mixers were confirmed by the X-ray Diffraction analysis. Wear rate (mm3/m, Wear resistance (m/mm3, Specific Wear rate (m/Nm and Co-efficient of friction (μ were analysed with various conditions. The worn surfaces were analysed before and after wear testing by Scanning Electron Microscope (SEM. Influence of process parameters and Percentage of contribution were analysed by Taguchi and Analysis of Variance (ANOVA methods. Genetic Algorithm (GA was adopted for optimizing the best and mean of the wear rate and to identify the exact influence of input parameters.

  12. Critical component wear in heavy duty engines

    CERN Document Server

    Lakshminarayanan, P A

    2011-01-01

    The critical parts of a heavy duty engine are theoretically designed for infinite life without mechanical fatigue failure. Yet the life of an engine is in reality determined by wear of the critical parts. Even if an engine is designed and built to have normal wear life, abnormal wear takes place either due to special working conditions or increased loading.  Understanding abnormal and normal wear enables the engineer to control the external conditions leading to premature wear, or to design the critical parts that have longer wear life and hence lower costs. The literature on wear phenomenon r

  13. Effect of porosity on wear resistance of SiCp/Cu composites prepared by pressureless infiltration

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin; QU Xuan-hui; DUAN Bo-hua; HE Xin-bo; QIN Ming-li

    2008-01-01

    The influence of porosity on the wear behavior of high volume fraction (61%) SiCp/Cu composite produced by pressureless infiltration was studied using a sliding, reciprocating and vibrating(SRV) machine. SiCp/Cu composites slid against hardened GCr15 bearing steel ball in the load range of 40-200 N. The results show that the wear rate increases with increasing porosity. The composite containing low porosity shows excellent wear resistance, which is attributed to the presence of mechanically mixed layer on the worn surface. In this case, the dominant wear mechanism is oxidative wear. Comparatively, the composite containing high porosity exhibits inferior wear resistance. Fracture and spalling of the particles are considered as the main causes of severe wear. Third body abrasion is the controlling wear mechanism. In addition, porosity has more important influence on wear rate at high load than at low load. This is associated with the fact that the fracture and spalling of particles is a process of crack initiation and propagation. At lower load, the pores beneath the worn surface can not propagate significantly, while the pores become unstable and easily propagate under high load, which results in a higher wear rate.

  14. Wear Characteristics of Ni-Based Hardfacing Alloy Deposited on Stainless Steel Substrate by Laser Cladding

    Science.gov (United States)

    Awasthi, Reena; Limaye, P. K.; Kumar, Santosh; Kushwaha, Ram P.; Viswanadham, C. S.; Srivastava, Dinesh; Soni, N. L.; Patel, R. J.; Dey, G. K.

    2015-03-01

    In this study, dry sliding wear characteristics of the Ni-based hardfacing alloy (Ni-Mo-Cr-Si) deposited on stainless steel SS316L substrate by laser cladding have been presented. Dry sliding wear behavior of the laser clad layer was evaluated against two different counter bodies, AISI 52100 chromium steel (~850 VHN) and tungsten carbide ball (~2200 VHN) to study both adhesive and abrasive wear characteristics, in comparison with the substrate SS316L using ball on plate reciprocating wear tester. The wear resistance was evaluated as a function of load and sliding speed for a constant sliding amplitude and sliding distance. The wear mechanisms were studied on the basis of wear surface morphology and microchemical analysis of the wear track using SEM-EDS. Laser clad layer of Ni-Mo-Cr-Si on SS316L exhibited much higher hardness (~700 VHN) than that of substrate SS316L (~200 VHN). The laser clad layer exhibited higher wear resistance as compared to SS316L substrate while sliding against both the counterparts. However, the improvement in the wear resistance of the clad layer as compared to the substrate was much higher while sliding against AISI 52100 chromium steel than that while sliding against WC, at the same contact stress intensity.

  15. Engineering Dark Chromoprotein Reporters for Photoacoustic Microscopy and FRET Imaging

    Science.gov (United States)

    Li, Yan; Forbrich, Alex; Wu, Jiahui; Shao, Peng; Campbell, Robert E.; Zemp, Roger

    2016-03-01

    A subset of the family of fluorescent proteins are the non-fluorescent chromoproteins which are promising probe molecules for use in photoacoustic imaging and as acceptor chromophores in Förster resonance energy transfer (FRET)-based biosensors. Typical approaches for fluorescent protein optimization by screening of large libraries of variants cannot be effectively applied to chromoproteins due to their characteristic lack of fluorescence. To address this challenge, we have developed a directed evolution method to iteratively screen large libraries of protein variants on the basis of their photoacoustic signal levels. By applying this procedure to the promising Ultramarine and cjBlue chromoprotein templates, we were able to identify improved variants with a 02-04 fold increase in photoacoustic signal-to-noise ratio after only a few evolutionary steps. These improved variants enable more accurate spectral de-mixing and localization of protein-producing bacteria in vivo and serve as effective FRET acceptors for both fluorescence- and photoacoustic-based detection of protease activity.

  16. Crack path simulation for cylindrical contact under fretting conditions

    Directory of Open Access Journals (Sweden)

    R.A. Cardoso

    2016-02-01

    Full Text Available In this work different strategies to estimate crack path for cylindrical contacts under fretting conditions are carried out. The main goal is to propose and to evaluate methodologies not only to estimate the direction of crack initiation but also the subsequent propagation in its earlier stages, where the stress field is multiaxial, non-proportional and decays very fast due to the proximity with the contact interface. Such complex conditions pose a substantial challenge to the modelling of crack path. The numerical simulations are provided by a 2D Finite Element Analysis taking into account interactions between the crack faces. The results show that, under fretting conditions, models based on the critical plane method are not effective to estimate the crack initiation orientation, while models based on a so called “critical direction” applied along a critical distance provide better results. Regarding the subsequent crack propagation orientation, it was possible to see that stress intensity factor based models where one considers an infinitesimal virtual crack emerging from an original preexistent crack are powerful mechanisms of crack orientation estimation.

  17. Paths to Förster's resonance energy transfer (FRET) theory

    Science.gov (United States)

    Masters, B. R.

    2014-02-01

    Theodor Förster (1910-1974) developed a phenomenological theory of nonradiative resonance energy transfer which proved to be transformative in the fields of chemistry, biochemistry, and biology. This paper explores the experimental and the theoretical antecedents of Förster's theory of resonance energy transfer (FRET). Early studies of sensitized fluorescence, fluorescence depolarization, and photosynthesis demonstrated the phenomena of long-range energy transfer. At the same time physicists developed theoretical models which contained common physical mechanisms and parameters: oscillating dipoles as models for the atoms or molecules, dipole-dipole coupling for the interaction, and a distance R0 that is optimal for resonance energy transfer. Early theories predicted R0 that was too large as compared to experiments. Finally, in 1946 Förster developed a classical theory and in 1948 he developed a quantum mechanical theory; both theories predicted an inverse sixth power dependence of the rate of energy transfer and a R0 that agreed with experiments. This paper attempts to determine why Förster succeeded when the other theoreticians failed to develop the correct theory. The putative roles of interdisciplinary education and collaborative research are discussed. Furthermore, I explore the role of science journals and their specific audiences in the popularization of FRET to a broad interdisciplinary community.

  18. Total hip wear assessment: a comparison between computational and in vitro wear assessment techniques using ISO 14242 loading and kinematics.

    Science.gov (United States)

    Matsoukas, George; Willing, Ryan; Kim, Il Yong

    2009-04-01

    In the present study a direct comparison was made between in vitro total hip wear testing and a computational analysis considering the effects of time and a nonlinear stress-strain relationship for ultrahigh molecular weight polyethylene (UHMWPE) at 37 degrees C. The computational simulation was made correct through calibration to experimental volumetric wear results, and the predicted damage layout on the acetabular liner surface was compared with results estimated from laser scanning of the actual worn specimens. The wear rates for the testing specimens were found to be 17.14+/-1.23 mg/10(6) cycles and 19.39+/-0.79 mg/10(6) cycles, and the cumulative volumetric wear values after 3x10(6) cycles were 63.70 mm(3) and 64.02 mm(3) for specimens 1 and 2, respectively. The value of the calibrated wear coefficient was found to be 5.32(10(-10)) mm(3)/N mm for both specimens. The major difference between the computational and experimental wear results was the existence of two damage vectors in the experimental case. The actual location of damage was virtually the same in both cases, and the maximum damage depth of the computational model agreed well with the experiment. The existence of multiple wear vectors may indicate the need for computational approaches to account for multidirectional sliding or strain hardening of UHMWPE. Despite the limitation in terms of describing the overall damage layout, the present computational model shows that simulation can mimic some of the behavior of in vitro wear.

  19. Study on quantitative relation between characteristics of striature bionic coupling unit and wear resistance of gray cast iron

    Science.gov (United States)

    Pang, Zuobo; Zhou, Hong; Zhang, Peng; Cong, Dalong; Meng, Chao; Wang, Chuanwei; Ren, Luquan

    2015-03-01

    In order to improve the wear resistance of gray cast iron guide rail, striature bionic coupling units of different characteristics were manufactured by laser surface remelting. Wear behavior of gray cast iron with striature bionic coupling units has been studied under dry sliding condition at room temperature using a homemade linear reciprocating wear testing machine. The wear resistance was evaluated by means of weight loss measurement and wear morphology. The results indicated that there is a relationship between weight loss and the area of striature bionic coupling units and α: Δm = Δm0 - 0.0212S × cos α - 0.0241S × sin α.

  20. Influence of Cycle Temperature on the Wear Resistance of Vermicular Iron Derivatized with Bionic Surfaces

    Science.gov (United States)

    Sui, Qi; Zhang, Peng; Zhou, Hong; Liu, Yan; Ren, Luquan

    2016-11-01

    Depending on their applications, such as in brake discs, camshafts, etc., the wear behavior of vermicular iron is influenced by the thermal cycling regime. The failure of a working part during its service life is a consequence of both thermal fatigue and wear. Previously, the wear and thermal fatigue resistance properties of vermicular iron were separately investigated by researchers, rather than a study combining these two factors. In the present work, the effect of cycle temperature on the wear resistance of specimens with bionic units processed by laser has been investigated experimentally. The wear behavior pre- and post-thermal cycling has also been investigated, and the influence of different cycle temperatures on the wear resistance is discussed. The results indicate that the thermal cycling regime brought about negative influences with varying degrees, on the material properties, such as the microstructures, micro-hardness, cracks, and oxidation resistance properties. All these factors synergistically reduced the wear resistance of vermicular iron. In particular, the negative influence apparently increased with an increase in cycle temperature. Nevertheless, the post-thermal-cycle wear resistance of the specimens with bionic units was superior to those without bionic units. Hence, the laser bionic process is an effective way to improve the performance of vermicular iron in combined thermal cycling and wear service conditions.

  1. Fluorescence resonance energy transfer (FRET) in chemistry and biology: Non-Förster distance dependence of the FRET rate

    Indian Academy of Sciences (India)

    Sangeeta Saini; Harjinder Singh; Biman Bagchi

    2006-01-01

    Fluorescence resonance energy transfer (FRET) is a popular tool to study equilibrium and dynamical properties of polymers and biopolymers in condensed phases and is now widely used in conjunction with single molecule spectroscopy. In the data analysis, one usually employs the Förster expression which predicts (1/6) distance dependence of the energy transfer rate. However, critical analysis shows that this expression can be of rather limited validity in many cases. We demonstrate this by explicitly considering a donor-acceptor system, polyfluorene (PF6)-tetraphenylporphyrin (TPP), where the size of both donor and acceptor is comparable to the distance separating them. In such cases, one may expect much weaker distance (as 1/2 or even weaker) dependence. We have also considered the case of energy transfer from a dye to a nanoparticle. Here we find 1/4 distance dependence at large separations, completely different from Förster. We also discuss recent application of FRET to study polymer conformational dynamics.

  2. Comportamiento del desgaste del flanco en el torneado en seco de alta velocidad del acero AISI 316L//Flank wear behavior in the dry high‐speed turning of AISI 316L stainless steel

    Directory of Open Access Journals (Sweden)

    Yoandrys Morales-Tamayo

    2013-09-01

    Full Text Available El presente estudio experimental se centra en investigar los efectos de los parámetros corte en el desgaste de flanco con dos insertos recubiertos durante el torneado de acabado en seco a altas velocidades del acero inoxidable AISI 316L. Los efectos de los parámetros de corte fueron determinados utilizando un análisis de varianza y de regresión simple. Como principal resultado se obtuvo el efectosignificativo del avance y del tiempo de maquinado en el desgaste del flanco. El inserto de tres capas no sobrepasó el criterio de fin de vida del desgaste, mientras que el inserto de una capa sufrió un desgaste catastrófico para la mayor velocidad de corte. El desgaste del flanco tuvo mejor comportamiento para el avance de 0,08 mm/rev en todas las velocidades empleadas en este estudio.Palabras claves: torneado de alta velocidad, desgaste de flanco, acero inoxidable AISI 316L, estudio experimental, análisis de varianza y regresión.______________________________________________________________________________AbstractThe current experimental study is focused on investigating the effects of cutting parameters on flank wear in two coated carbide inserts during dry high speed finish turning of AISI 316L stainless steel. The effects of cutting parameters were determinate using analysis of variance and simple regression. As a main resulta significant effect of cutting feed and the machining time on flank wear was found. The three coating layers insert did not exceed the criterion of end of life of wear while the insert with one layer suffered a catastrophic wear at the highest cutting speed. The flank wear showed the best performance for the cuttingfeed of 0,08 mm/rev at all the speeds used in the study.Key words: high speed turning; flank wear; AISI 316L stainless steel, experimental study; analysis of variance and regression.

  3. Friction and Wear Behavior of Two NiCrA1Y Coatings at Room Temperature%两种NiCrAlY涂层的室温摩擦磨损性能

    Institute of Scientific and Technical Information of China (English)

    张健; 郭策安; 张罡; 郝士明

    2011-01-01

    The friction and wear properties of a sputtered NiCrAlY coating and an electrospark deposited (ESD) NiCrAlY on CrNi3MoVA steel substrate coating were investigated at room temperature. The results show that the friction coefficient of the two coatings is lower than that of the substrate during stable wearing course. The electrospark deposited NiCrAlY coating has a significant antifriction effect because its friction coefficient value is much lower than the sputtered one. The wear mechanism of the sputtered NiCrAlY coating could be mainly characterised by adhesive wear while the dominant wear mechanism for electrospark deposited NiCrAlY coating is micro-abrasive wear.%分别测试在CrNi3MoVA钢表面溅射NiCrAlY涂层和电火花沉积NiCrAlY涂层的室温摩擦磨损性能,研究了磨损机制.结果表明:在稳定磨损阶段,两种涂层的摩擦系数均低于基体,其中电火花沉积层的摩擦系数最小,具有显著的减摩效果.溅射涂层的磨损机制主要是粘着磨损,而电火花沉积层的磨损机制主要是微切削磨料磨损.

  4. Partially reduced graphene oxide based FRET on fiber-optic interferometer for biochemical detection

    Science.gov (United States)

    Yao, B. C.; Wu, Y.; Yu, C. B.; He, J. R.; Rao, Y. J.; Gong, Y.; Fu, F.; Chen, Y. F.; Li, Y. R.

    2016-03-01

    Fluorescent resonance energy transfer (FRET) with naturally exceptional selectivity is a powerful technique and widely used in chemical and biomedical analysis. However, it is still challenging for conventional FRET to perform as a high sensitivity compact sensor. Here we propose a novel ‘FRET on Fiber’ concept, in which a partially reduced graphene oxide (prGO) film is deposited on a fiber-optic modal interferometer, acting as both the fluorescent quencher for the FRET and the sensitive cladding for optical phase measurement due to refractive index changes in biochemical detection. The target analytes induced fluorescence recovery with good selectivity and optical phase shift with high sensitivity are measured simultaneously. The functionalized prGO film coated on the fiber-optic interferometer shows high sensitivities for the detections of metal ion, dopamine and single-stranded DNA (ssDNA), with detection limits of 1.2 nM, 1.3 μM and 1 pM, respectively. Such a prGO based ‘FRET on fiber’ configuration, bridging the FRET and the fiber-optic sensing technology, may serve as a platform for the realization of series of integrated ‘FRET on Fiber’ sensors for on-line environmental, chemical, and biomedical detection, with excellent compactness, high sensitivity, good selectivity and fast response

  5. N-way FRET microscopy of multiple protein-protein interactions in live cells.

    Directory of Open Access Journals (Sweden)

    Adam D Hoppe

    Full Text Available Fluorescence Resonance Energy Transfer (FRET microscopy has emerged as a powerful tool to visualize nanoscale protein-protein interactions while capturing their microscale organization and millisecond dynamics. Recently, FRET microscopy was extended to imaging of multiple donor-acceptor pairs, thereby enabling visualization of multiple biochemical events within a single living cell. These methods require numerous equations that must be defined on a case-by-case basis. Here, we present a universal multispectral microscopy method (N-Way FRET to enable quantitative imaging for any number of interacting and non-interacting FRET pairs. This approach redefines linear unmixing to incorporate the excitation and emission couplings created by FRET, which cannot be accounted for in conventional linear unmixing. Experiments on a three-fluorophore system using blue, yellow and red fluorescent proteins validate the method in living cells. In addition, we propose a simple linear algebra scheme for error propagation from input data to estimate the uncertainty in the computed FRET images. We demonstrate the strength of this approach by monitoring the oligomerization of three FP-tagged HIV Gag proteins whose tight association in the viral capsid is readily observed. Replacement of one FP-Gag molecule with a lipid raft-targeted FP allowed direct observation of Gag oligomerization with no association between FP-Gag and raft-targeted FP. The N-Way FRET method provides a new toolbox for capturing multiple molecular processes with high spatial and temporal resolution in living cells.

  6. Simultaneous live cell imaging using dual FRET sensors with a single excitation light.

    Directory of Open Access Journals (Sweden)

    Yusuke Niino

    Full Text Available Fluorescence resonance energy transfer (FRET between fluorescent proteins is a powerful tool for visualization of signal transduction in living cells, and recently, some strategies for imaging of dual FRET pairs in a single cell have been reported. However, these necessitate alteration of excitation light between two different wavelengths to avoid the spectral overlap, resulting in sequential detection with a lag time. Thus, to follow fast signal dynamics or signal changes in highly motile cells, a single-excitation dual-FRET method should be required. Here we reported this by using four-color imaging with a single excitation light and subsequent linear unmixing to distinguish fluorescent proteins. We constructed new FRET sensors with Sapphire/RFP to combine with CFP/YFP, and accomplished simultaneous imaging of cAMP and cGMP in single cells. We confirmed that signal amplitude of our dual FRET measurement is comparable to of conventional single FRET measurement. Finally, we demonstrated to monitor both intracellular Ca(2+ and cAMP in highly motile cardiac myocytes. To cancel out artifacts caused by the movement of the cell, this method expands the applicability of the combined use of dual FRET sensors for cell samples with high motility.

  7. Friction and Wear Behavior of Titania Nanotube Layers with Different Thicknesses on Titanium Surface%钛表面不同厚度氧化钛纳米管层的摩擦磨损行为

    Institute of Scientific and Technical Information of China (English)

    罗锦洁; 冯波; 郭振永; 范兴平; 屈树新

    2012-01-01

    为了改善钛的摩擦学性能,采用阳极氧化法在钛表面制备了纳米管径约100 nm,厚度分别为500 nm、1 000 nm和1 500 nm的TiO2纳米管层,并在450℃保温3h进行热处理.对试样的表面形貌、显微硬度和粗糙度进行测试.利用摩擦磨损试验考察了热处理前后不同试样在大气环境下的摩擦磨损行为.结果表明:干摩擦下,纳米管层的存在降低了钛与GCr15轴承钢球之间的摩擦系数;随TiO2纳米管层厚度的增加,试样的摩擦因数逐渐降低,磨损逐渐下降;热处理使纳米管由无定型氧化钛转变为锐钛矿晶型,进一步降低了摩擦因数,增加了钛的耐磨性能;纳米管层的磨损机制为磨粒磨损,接触疲劳磨损和粘着磨损.%To improve the tribological properties of titanium, anodic oxidation was used to fabricate a series of nanotube layers on Ti surface with the same inner diameter about 100 nm and different thicknesses of 500 nm, 1 000 nm and 1 500 nm. Specimens were heat-treated at 450 ℃ for 3 h. Morphology, micro-hardness and rough-ness of specimens surface were measured. The friction and wear properties of the specimens treated before and after heat - treatment in atmosphere were investigated by friction and wear experiments. The results indicate that in dry friction condition, the friction coefficients between Ti and GCrl5 bearing steel ball decrease due to the existence of nanotube layers. The friction coefficients and wear rates decrease with the increase of the nanotube thickness. Amorphous titania nanotubes transform into anatase through heat - treatment, which re-duces the friction factor and increases the wear resistance of titanium. The wear mechanisms of the nanotube layers involve abrasive wear, fatigue wear and adhesive wear.

  8. Abrasive Wear Study of NiCrFeSiB Flame Sprayed Coating

    Science.gov (United States)

    Sharma, Satpal

    2013-10-01

    In the present study, abrasive wear behavior of NiCrFeSiB alloy coating on carbon steel was investigated. The NiCrFeSiB coating powder was deposited by flame spraying process. The microstructure, porosity and hardness of the coatings were evaluated. Elemental mapping was carried out in order to study the distribution of various elements in the coating. The abrasive wear behavior of these coatings was investigated under three normal loads (5, 10 and 15 N) and two abrasive grit sizes (120 and 320 grit). The abrasive wear rate was found to increase with the increase of load and abrasive size. The abrasive wear resistance of coating was found to be 2-3 times as compared to the substrate. Analysis of the scanning electron microscope images revealed cutting and plowing as the material removal mechanisms in these coatings under abrasive wear conditions used in this investigation.

  9. Vibration analysis of shell-and-tube heat exchangers: an overview-Part 2: vibration response, fretting-wear, guidelines

    Science.gov (United States)

    Pettigrew, M. J.; Taylor, C. E.

    2003-11-01

    Design guidelines were developed to prevent tube failures due to excessive flow-induced vibration in shell-and-tube heat exchangers. An overview of vibration analysis procedures and recommended design guidelines is presented in this paper. This paper pertains to liquid, gas and two-phase heat exchangers such as nuclear steam generators, reboilers, coolers, service water heat exchangers, condensers, and moisture-separator-reheaters. Part 2 of this paper covers forced vibration excitation mechanisms, vibration response prediction, resulting damage assessment, and acceptance criteria.

  10. Preparation of mononucleosomal templates for analysis of transcription with RNA polymerase using spFRET.

    Science.gov (United States)

    Kudryashova, Kseniya S; Chertkov, Oleg V; Nikitin, Dmitry V; Pestov, Nikolai A; Kulaeva, Olga I; Efremenko, Anastasija V; Solonin, Alexander S; Kirpichnikov, Mikhail P; Studitsky, Vasily M; Feofanov, Alexey V

    2015-01-01

    Single positioned nucleosomes have been extensively employed as simple model experimental systems for analysis of various intranuclear processes. Here we describe an experimental system containing positioned mononucleosomes allowing transcription by various RNA polymerases. Each DNA template contains a pair of fluorescent labels (Cy3 and Cy5) allowing measuring relative distances between the neighboring coils of nucleosomal DNA using Forster resonance energy transfer (FRET). The single-particle FRET (spFRET) approach for analysis of DNA uncoiling from the histone octamer during transcription through chromatin is described in detail.

  11. Single-Molecule FRET Reveals Hidden Complexity in a Protein Energy Landscape

    OpenAIRE

    Tsytlonok, Maksym; Ibrahim, Shehu M.; Rowling, Pamela J.E.; Xu, Wenshu; Ruedas-Rama, Maria J.; Orte, Angel; Klenerman, David; Itzhaki, Laura S.

    2015-01-01

    Summary Here, using single-molecule FRET, we reveal previously hidden conformations of the ankyrin-repeat domain of AnkyrinR, a giant adaptor molecule that anchors integral membrane proteins to the spectrin-actin cytoskeleton through simultaneous binding of multiple partner proteins. We show that the ankyrin repeats switch between high-FRET and low-FRET states, controlled by an unstructured “safety pin” or “staple” from the adjacent domain of AnkyrinR. Opening of the safety pin leads to unrav...

  12. Fretting Fatigue Improvement of Ti6Al4V by Coating and Shot Peening

    Institute of Scientific and Technical Information of China (English)

    Daoxin LIU; Xiaodong ZHU; Bin TANG; Jiawen HE

    2005-01-01

    Ion beam enhanced deposition (IBED) was employed to increase the fretting fatigue resistance of Ti6AI4V. CrN and TiN hard coatings were applied on the base material and shot peening was combined with the hard coatings to study the duplex effect on fretting fatigue resistance, The IBED coatings exhibited a good bonding strength. They did not spall off even after shot peening. However, an optimum composition of CrN showed better fretting fatigue resistance than that of TiN with the same processing parameters.

  13. Lateral diffusion contributes to FRET from lanthanide-tagged membrane proteins.

    Science.gov (United States)

    Lan, Tien-Hung; Wu, Guangyu; Lambert, Nevin A

    2015-08-14

    Diffusion can enhance Förster resonance energy transfer (FRET) when donors or acceptors diffuse distances that are similar to the distances separating them during the donor's excited state lifetime. Lanthanide donors remain in the excited state for milliseconds, which makes them useful for time-resolved FRET applications but also allows time for diffusion to enhance energy transfer. Here we show that diffusion dramatically enhances FRET between membrane proteins labeled with lanthanide donors. This phenomenon complicates interpretation of experiments that use long-lived donors to infer association or proximity of mobile membrane proteins, but also offers a method of monitoring diffusion in membrane domains in real time in living cells.

  14. Calculation of wear (f.i. wear modulus) in the plastic cup of a hip joint prosthesis

    NARCIS (Netherlands)

    Ligterink, D.J.

    1975-01-01

    The wear equation is applied to the wear process in a hi