WorldWideScience

Sample records for ceramic particle reinforcement

  1. Fracture and toughening of high volume fraction ceramic particle reinforced metals

    OpenAIRE

    Miserez, Ali Gilles Tchenguise; Mortensen, Andreas

    2005-01-01

    This work contributes to the fundamental understanding of fracture properties of Particle Reinforced Metal Matrix Composites (PRMMCs), by identifying the key microstructural parameters that control fracture. To this end, PRMMCs with a high volume fraction of ceramic reinforcement (40-60 vol.%) are produced by gas-pressure infiltration. These composites are considered as model ductile/brittle twophase materials in that (i): the particles are homogeneously distributed in the matrix, (ii): the m...

  2. Reinforcement of ceramic materials

    International Nuclear Information System (INIS)

    In the commercial field, greater reproduceability of ceramic materials was achieved by systematic process control of the steps in manufacture. By improvement of the microstructure design, the strength and toughness against tearing of the materials were increased. The articles give a survey of theoretical and experimental results in manufacture and of the composition of ceramics with reinforced structure. Preferred materials are zirconium-, aluminium- and yttrium oxide, silicon oxide and -nitride and titanium- and silicon carbide. (DG)

  3. Custom fabrication of reinforced lithium disilicate ceramic ingot

    Science.gov (United States)

    Chander, Gopi Naveen; Sasikala, C.; Mutukumar, B.; Dhanasekar, N.

    2016-01-01

    A method of formulating a reinforcement lithium disilicate ceramic ingot was proposed. The ceramic ingot was broken manually with a mallet to finer particles. The sectioned ingot is ball milled along with 10% of nano zirconia by weight to obtain the desired powder. The reinforced powder is condensed in a 5 ml disposable syringe by powder slurry technique. The compacted ceramic were sintered at 900°C to obtain ceramic ingots. The reinforced ceramic ingots were used in pressable ceramic machines to obtain the desired advantages of zirconia reinforcement and pressable ceramic system.

  4. Wear resistance of PM composite materials reinforced with the Ti(C,N ceramic particles

    Directory of Open Access Journals (Sweden)

    A. Włodarczyk-Fligier

    2008-10-01

    Full Text Available Purpose: of the project was evaluation of the effect of heat treatment and of the reinforcing Ti(C,N particles in the EN AW-AlCu4Mg1(A aluminium alloy on the mechanical properties, wear resistance.Design/methodology/approach: some of the composite materials were hyperquenched for 0.5 h at the temperature of 495ºC with the subsequent cooling in water, and were quench aged next for 6 h at 200°C. Hardness tests were made on HAUSER hardness tester with the Vickers method at 10 N. Abrasion resistance wear tests were carried out with the constant number of cycles of 5000 (120 m at various loads: 4, 5, 6, 7, and 8 N. Test pieces were rinsed in the ultrasonic washer to clean them and next were weighed on the analytical balance with the accuracy of 0.0001 g to check the mass loss.Findings: Besides visible improvement of mechanical properties and wear resistance there were also observed the influence of heat treatment.Practical implications: Tested composite materials can be applied among others in automotive industry but it requires additional researches.Originality/value: It was demonstrated that the mechanical properties, as well as the wear resistance of the investigated composite materials with the EN AW-Al Cu4Mg1(A alloy matrix may be formed by the dispersion hardening with the Ti(C,N particles in various portions and by the precipitation hardening of the matrix.

  5. Solidification analysis of AMMCs with ceramic particles

    OpenAIRE

    J. Sleziona; M. Dyzia; A. Dolata-Grosz

    2007-01-01

    Purpose: In the research work the result of the reinforcement displacement and solidification analysis for aluminiumcast composites with ceramic particles have been presented. The results of research on the solidification procesare compared for the applied aluminium matrix alloy (AlSi12CuNiMg2), for composites containing glass carboparticles (Cg) and heterophase reinforcement (mixture of silicon carbide (SiC) + glass carbon particles (Cg)).Design/methodology/approach: The course of the solidi...

  6. Microstructure and mechanical properties of NiFe2O4 ceramics reinforced with ZrO2 particles with different sintering temperatures

    International Nuclear Information System (INIS)

    Highlights: ► ZrO2/NiFe2O4 composite ceramics were synthesized by powder metallurgy methods. ► The microstructure was investigated at different sintering temperatures. ► The grain size increases with increasing of the sintering temperature. ► The composite ceramics sintering at 1400°C show superior mechanical properties. ► Main toughening mechanisms are densification, phase transformation toughening. - Abstract: NiFe2O4 ceramics reinforced with ZrO2 particle was fabricated by conventional high-temperature solid state reaction. Effect of the sintering temperature (1100–1500 °C) on the microstructure and mechanical properties of the ZrO2/NiFe2O4 composite ceramics was investigated in detail. The fracture surfaces of NiFe2O4 composite ceramics were observed by scanning electron microscopy (SEM). Elemental analysis of micro-structural phases was performed using energy dispersive spectroscopy (EDS), attached with SEM. Flexural strength by three-point bending techniques and fracture toughness were measured. It was indicated that when the sintering temperature was above 1400 °C, phase transformation causing crack can directly lead to the strength degradation. The grain size of ZrO2 increases with increasing of the sintering temperature. The samples sintering at 1400 °C had the highest flexural strength of 192 ± 10 MPa and fracture toughness of 3.38 ± 0.05 MPa m1/2 due to densification, phase transformation.

  7. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rajendra Bordia

    2009-07-31

    The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and

  8. Solidification analysis of AMMCs with ceramic particles

    Directory of Open Access Journals (Sweden)

    J. Sleziona

    2007-07-01

    Full Text Available Purpose: In the research work the result of the reinforcement displacement and solidification analysis for aluminiumcast composites with ceramic particles have been presented. The results of research on the solidification procesare compared for the applied aluminium matrix alloy (AlSi12CuNiMg2, for composites containing glass carboparticles (Cg and heterophase reinforcement (mixture of silicon carbide (SiC + glass carbon particles (Cg.Design/methodology/approach: The course of the solidification process was recorded by means of a systemwhich enabled continuous control and measurement of the metal temperature during solidification of the compositsuspension. The system was equipped with a thermoelectric cup core QC4080, with an incorporated thermocouple oK type (NiCr-Ni. The application of disposable thermoelectric cup cores of identical heat abstraction coefficient anknown, standardized dimensions, ensured identical conditions and rate of heat abstraction during the cooling of thcastings. The structure analysis for composite casts was performed by means of optical and scanning microscopy.Findings: The research has shown, that ceramic particles have an influence on temperature change and the timof aluminium matrix alloy solidification. The changes results, first of all, from disparate physical properties othe glassy carbon particles and silicon carbide particles used (thermal conductivity, mass density, compared taluminium matrix alloy.Practical implications: Ceramic particles decrease shrinkage of the casting and change the nature of itcrystallization.Originality/value: Employment of glass carbon particles for matrix reinforcement allows to get flotation in thaluminium alloy. Employment of heterophase reinforcement (glass carbon and silicon carbide particles allows tget segregation of particles: flotation as well as sedimentation in the matrix, which results in the occurrence of layered structure.

  9. Fracture Toughness Prediction for MWCNT Reinforced Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H.; Nguyen, Ba Nghiep

    2013-09-01

    This report describes the development of a micromechanics model to predict fracture toughness of multiwall carbon nanotube (MWCNT) reinforced ceramic composites to guide future experimental work for this project. The modeling work described in this report includes (i) prediction of elastic properties, (ii) development of a mechanistic damage model accounting for matrix cracking to predict the composite nonlinear stress/strain response to tensile loading to failure, and (iii) application of this damage model in a modified boundary layer (MBL) analysis using ABAQUS to predict fracture toughness and crack resistance behavior (R-curves) for ceramic materials containing MWCNTs at various volume fractions.

  10. Ceramic fiber reinforced glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam P. (Inventor)

    1993-01-01

    A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

  11. Development of ceramic-reinforced photopolymers for SLA 3D printing technology

    Science.gov (United States)

    Yun, Ji Sun; Park, Tae-Wan; Jeong, Young Hun; Cho, Jeong Ho

    2016-06-01

    Al2O3 ceramic-reinforced photopolymer samples for SLA 3D printing technology were prepared using a silane coupling agent (VTES, vinyltriethoxysilane). Depending on the method used to coat the VTES onto the ceramic surface, the dispersion of ceramic particles in the photopolymer solution was remarkably improved. SEM, TEM and element mapping images showed Al2O3 particles well wrapped with VTES along with well-distributed Al2O3 particles overall on the cross-sectional surfaces of 3D-printed objects. The tensile properties (stress-strain curves) of 3D-printed objects of the ceramic-reinforced photopolymer were investigated as a function of the Al2O3 ceramic content when it ranged from 0 to 20 wt%. The results demonstrate that an Al2O3 ceramic content of 15 wt% resulted in enhanced tensile characteristics.

  12. Corrosion resistance of the sintered composite materials with the EN AW-AlCu4Mg1(a alloy matrix reinforced with ceramic particles

    Directory of Open Access Journals (Sweden)

    A. Włodarczyk-Fligier

    2010-09-01

    Full Text Available Purpose: the aim of the project was to evaluate of the effect of heat treatment and the reinforcing Al2O3 and Ti(C,N particles content on the corrosion resistance in the NaCl water solution environment on the EN AW-AlCu4Mg1(A aluminium alloy matrix composite.Design/methodology/approach: Powders of the starting materials were wet mixed in the laboratory vibratory ball mill to obtain the uniform distribution of the reinforcement particles in the matrix. The mixed powders were then dried in the air. The components were initially compacted at cold state in a die with the diameter of Ø 26 mm in the laboratory vertical unidirectional press – with a capacity of 350 kN. The selected compacting load was sufficient to obtain prepregs which would not crumble and at the same time would not be deformed too much, which would also have the adverse effect on their quality, as the excessive air pressure in the closed pores causes breaking the prepreg up when it is taken out from the die. The obtained PM compacts were heated to a temperature of 480-500˚C and finally extruded – with the extrusion pressure of 500 kN. Some of the composite materials were hyperquenched for 0.5 h at the temperature of 495ºC with the subsequent cooling in water, and were quench aged next for 6 h at 200°C. Corrosion tests were made in 5% water NaCl solution.Findings: Composite materials were examined without heat treatment and after heat treatment carried out to improve their corrosion resistance. The corrosion susceptibility of the investigated composite materials determined using the potentiodynamic method in the 3% water solution of NaCl depends on the volume fraction of the reinforcing particles and also on the heat treatment status.Practical implications: Tested composite materials can be applicate among the others in automotive industry but it requires additional researches.Originality/value: It was demonstrated corrosion resistance of the extruded composite materials with

  13. Reciprocal sliding wear of SiC particle reinforced Al-Cu aluminium matrix composites against stainless steel, high speed tool steel and ceramics. Pt. 1. Tribological properties and construction of tribo-maps

    Energy Technology Data Exchange (ETDEWEB)

    Bai Mingwu [Lab. of Solid Lubrication, Lanzhou Inst. of Chemical Physics, Lanzhou (China); Xue Qunji [Lab. of Solid Lubrication, Lanzhou Inst. of Chemical Physics, Lanzhou (China); Guo Huifang [Inst. of Powder Metallurgy, Central-South Univ. of Technology, Changsha (China)

    1996-07-01

    The SiC particle reinforced Al-Cu aluminum matrix composites were dry sliding against 4Cr13, W{sub 18}Cr{sub 4}V steel and Si{sub 3}N{sub 4} ceramics on a reciprocal sliding wear testing machine at ambient conditions. Experiments were performed within a normal load range of 20 to 175 N and a sliding velocity of 0.075 to 1.2 m s{sup -1}. It was found that there was a big friction coefficient and friction fluctuation at low reciprocal velocity and very low friction coefficient at very high reciprocal velocity. The composite pins in composite/W{sub 18}Cr{sub 4}V tribo-pairs had greatest wear resistance in three kinds of tribo-pairs. The wear maps of the three kinds of tribo-pairs constructed to illustrate the sliding wear characteristics of the composites. (orig.)

  14. Ceramic fiber-reinforced monoclinic celsian phase glass-ceramic matrix composite material

    Science.gov (United States)

    Bansal, Narottam P. (Inventor); Dicarlo, James A. (Inventor)

    1994-01-01

    A hyridopolysilazane-derived ceramic fiber reinforced monoclinic celsian phase barium aluminum silicate glass-ceramic matrix composite material is prepared by ball-milling an aqueous slurry of BAS glass powder and fine monoclinic celsian seeds. The fibers improve the mechanical strength and fracture toughness and with the matrix provide superior dielectric properties.

  15. Composite materials based on EN AW-Al Cu4Mg1(A aluminum alloy reinforced with the BN ceramic particles

    Directory of Open Access Journals (Sweden)

    P. Bała

    2010-03-01

    Full Text Available Purpose: The concept of new tool materials, based on Ni alloys strengthened by intermetallic compounds, intended for operations in high temperatures is presented in the hereby paper. The proposed chemical composition and the results of microstructure investigations as well as hardness testing in as-cast condition – are given.Design/methodology/approach: A test melt of a mass of approximately 1 kg was done in a vacuum furnace, and cast into a ceramic mould. The microstructure of the investigated material was examined by a light microscope Axiovert 200 MAT and the scanning electron microscope FIB Zeiss NEON 40EsB CrossBeam. Dilatometric experiment was performed by means of the Adamel Lhomargy DT 1000 dilatometer .Findings: The main components of the microstructure of the nickel-base investigated alloy are: the γ phase, which constitutes the matrix and the γ’ phase. This γ’ phase occurs as fine globular precipitates as well as in a form of primary Ta carbides of MC type. Primary carbides of irregular shapes are uniformly distributed not forming agglomerates. The assumed volume fraction of the primary carbides was achieved.Research limitations/implications: Identification of microstructure components on Ni-based materials strengthened by particles of intermetallic phases of a high carbon content.Practical implications: New tool material for hot-working.Originality/value: The new chemical compositions of tool materials based on Ni alloys strengthened by intermetallic compounds with high carbon content.

  16. Composite materials based on EN AW-Al Cu4Mg1(A aluminum alloy reinforced with the BN ceramic particles

    Directory of Open Access Journals (Sweden)

    A. Włodarczyk-Fligier

    2010-03-01

    Full Text Available Purpose: the aim of the project was to evaluate of the effect of heat treatment and the reinforcing BN particles content on the mechanical properties, abrasive wear and corrosion resistance in the NaCl water solution environment on the EN AW-AlCu4Mg1(A aluminium alloy matrix composite.Design/methodology/approach: Some of the composite materials were hyperquenched for 0.5 h at the temperature of 495ºC with the subsequent cooling in water, and were quench aged next for 6 h at 200°C. Hardness tests were made on HAUSER hardness tester with the Vickers method at 10 N. Static compression and tensile tests of the fabricated composite materials were made on the ZWICK 100 type testing machine at room temperature. Abrasion resistance wear tests were carried out with the constant number of cycles of 5000 (120 m at various loads: 4, 5, 6, 7, and 8 N. Test pieces were rinsed in the ultrasonic washer to clean them and next were weighed on the analytical balance with the accuracy of 0.0001 g to check the mass loss. Corrosion tests were made in 5% water NaCl solution.Findings: Besides visible improvement of mechanical properties: hardness, compression strength and tensile strength, wear resistance there were also observed the influence of heat treatment on the corrosion resistance of composite materials in 3% NaCl solution.Practical implications: Tested composite materials can be applicate among the others in automotive industry but it requires additional researches.Originality/value: It was demonstrated that the mechanical properties, as well as the wear and corrosion resistance of the extruded composite materials with the EN AW-Al Cu4Mg1(A alloy matrix may be formed by the dispersion hardening with the BN particles in various portions and by the precipitation hardening of the matrix.

  17. Hollow sphere ceramic particles for abradable coatings

    International Nuclear Information System (INIS)

    A hollow sphere ceramic flame spray powder is disclosed. The desired constituents are first formed into agglomerated particles in a spray drier. Then the agglomerated particles are introduced into a plasma flame which is adjusted so that the particles collected are substantially hollow. The hollow sphere ceramic particles are suitable for flame spraying a porous and abradable coating. The hollow particles may be selected from the group consisting of zirconium oxide and magnesium zirconate

  18. Ceramic matrix reinforced by BN nanofillers

    Czech Academy of Sciences Publication Activity Database

    Kašiarová, M.; Tatarko, P.; Chlup, Zdeněk; Dlouhý, Ivo

    Košice : Slovak Silicate Society - ASSTS, 2015, s. 33-36. ISBN 978-80-553-2122-6. [International conference Preparation of Ceramics Materials /11./. Herľany (SK), 09.06.2015-11.06.2015] R&D Projects: GA MŠk(CZ) 7AMB14SK155 Institutional support: RVO:68081723 Keywords : 3Y-TZP zirconia * boron nitride nanotubes * spark plasma sintering Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  19. Whisker-reinforced ceramic composites for heat engine components

    Science.gov (United States)

    Duffy, Stephen F.

    1988-01-01

    Much work was undertaken to develop techniques of incorporating SiC whiskers into either a Si3N4 or SiC matrix. The result was the fabrication of ceramic composites with ever-increasing fracture toughness and strength. To complement this research effort, the fracture behavior of whisker-reinforced ceramics is studied so as to develop methodologies for the analysis of structural components fabricated from this toughened material. The results, outlined herein, focus on the following areas: the use of micromechanics to predict thermoelastic properties, theoretical aspects of fracture behavior, and reliability analysis.

  20. Processing and properties of pressable ceramic with non-uniform reinforcement for selective-toughening

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Wei [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); School of Dentistry, The University of Western Australia, WA 6009 (Australia); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China); Hu, Xiaozhi, E-mail: xiao.zhi.hu@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Ichim, Paul [School of Dentistry, The University of Western Australia, WA 6009 (Australia); Sun, Xudong [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China)

    2012-12-15

    Brittle low-strength and low-toughness pressable dental ceramic can be reinforced by ductile elongated gold-particles (GP). A customized crown structure can be adequately strengthened by distributing GP only in critical sections of the crown, where high tensile stresses are experienced. In the present study, a non-uniformly structured ceramic-matrix composite with excellent interfacial bonding, twofold fracture toughness and strength at desired locations, is fabricated using pressable dental ceramic and GP. The layout pattern and sequence of different GP/ceramic powder mixtures, high-temperature flow properties of these mixtures during hot-pressing and the sample mold geometry are used to control the distribution and locations of GP for selective toughening and strengthening. Nano-crystalline structures of the pressable ceramic-matrix and the nano-scaled interfacial region around GP have been revealed by high-magnification field-emission scanning electron microscopy. Toughening and strengthening mechanisms of the elongated GP including residual stresses from composite processing and ductile fracture of GP are discussed together with SEM observations. Bulk flexural strength and local micro-indentation fracture and deformation characteristics of the selective-toughened ceramic/metal composite have been compared to those of the monolithic pressable ceramic to validate the toughening and strengthening mechanisms.

  1. Boron carbide whisker and platelet reinforced ceramic matrix composites

    International Nuclear Information System (INIS)

    Boron carbide whisker and platelet-reinforced alumina and boron-carbide-whisker-reinforced silicon carbide composites were prepared by hot-pressing. The mechanical properties of hot-pressed boron carbide platelet and whisker-reinforced composites are better than the inherent ceramic matrix. A maximum fracture toughness, K(lc), of 9.5 MPa sq rt m is achieved for alumina/boron carbide whisker composites, 8.6 MPa sq rt m is achieved for alumina/boron carbide platelet composites, and 3.8 MPa sq rt m is achieved for silicon carbide/boron carbide whisker composites. The fracture toughness is dependent on the volume fraction of the platelets and whiskers. 12 refs

  2. Method of producing a ceramic fiber-reinforced glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam P. (Inventor)

    1994-01-01

    A fiber-reinforced composite composed of a BaO-Al2O3-2SiO2 (BAS) glass ceramic matrix is reinforced with CVD silicon carbide continuous fibers. A slurry of BAS glass powders is prepared and celsian seeds are added during ball melting. The slurry is cast into tapes which are cut to the proper size. Continuous CVD-SiC fibers are formed into mats of the desired size. The matrix tapes and the fiber mats are alternately stacked in the proper orientation. This tape-mat stack is warm pressed to produce a 'green' composite. The 'green' composite is then heated to an elevated temperature to burn out organic constituents. The remaining interim material is then hot pressed to form a silicon carbide fiber-reinforced celsian (BAS) glass-ceramic matrix composite which may be machined to size.

  3. Silver matrix composites reinforced with galvanically silvered particles

    Directory of Open Access Journals (Sweden)

    J. Śleziona

    2007-08-01

    Full Text Available Purpose: The paper presents the possibility of the application of metalic layers drifted with the use of the galvanic methods on the ceramic particles surface. The application of the layers was aimed at obtaining the rewetting of the reinforcing particles with the liquid silver in the course of the producing of silver matrix composites with the use of mechanical stirring method. To enable introducing of the iron powder and glass carbon powder to liquid silver the solution of covering the powder layer with the silver or copper coats was proposed.Design/methodology/approach: For silver coating the method of non-current deposition from the solution was used.Findings: Conducted investigations allowed such a selection of non-current coating parameters that durable and qualitatively satisfactory coats on the iron particles surface could be obtained.Research limitations/implications: In the course of the researches it was stated that the temperature of the bath, the time of the spread and the intensity of the stirring were the most important parameters of the deposition method itself that guaranteed the obtaining of the coat. The conducted investigations allow to state that the most favourably from the quality of the obtained composite point of view were the applications of the silver coat on the surface of the iron particles and copper coat for glass carbon covering.Originality/value: Selection of the deposited galvanic coats allows to obtain the good quality of the connection on the reinforcing particle sliver matrix interface.

  4. The Influence of the Particle Size on the Adhesion Between Ceramic Particles and Metal Matrix in MMC Composites

    Science.gov (United States)

    Jarzabek, Dariusz M.; Chmielewski, Marcin; Dulnik, Judyta; Strojny-Nedza, Agata

    2016-05-01

    This study investigated the influence of the particle size on the adhesion force between ceramic particles and metal matrix in ceramic-reinforced metal matrix composites. The Cu-Al2O3 composites with 5 vol.% of ceramic phase were prepared by a powder metallurgy process. Alumina oxide powder as an electrocorundum (Al2O3) powder with different particle sizes, i.e., fine powder materials and carried out the experiments with the use of the self-made tensile tester. We have observed that the interface strength is higher for the sample with coarse particles and is equal to 74 ± 4 MPa and it is equal to 68 ± 3 MPa for the sample with fine ceramic particles.

  5. Rapid Prototyping of Continuous Fiber Reinforced Ceramic Matrix Composites

    Science.gov (United States)

    Vaidyanathan, R.; Green, C.; Phillips, T.; Cipriani, R.; Yarlagadda, S.; Gillespie, J. W., Jr.; Effinger, M.; Cooper, K. C.

    2003-01-01

    For ceramics to be used as structural components in high temperature applications, their fracture toughness is improved by embedding continuous ceramic fibers. Ceramic matrix composite (CMC) materials allow increasing the overall operating temperature, raising the temperature safety margins, avoiding the need for cooling, and improving the damping capacity, while reducing the weight at the same time. They also need to be reliable and available in large quantities as well. In this paper, an innovative rapid prototyping technique to fabricate continuous fiber reinforced ceramic matrix composites is described. The process is simple, robust and will be widely applicable to a number of high temperature material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The results of mechanical properties and microstructural characterization are presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts at an order of magnitude lower cost than current chemical vapor infiltration (CVI) and polymer impregnation and pyrolysis (PIP) processes.

  6. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    Science.gov (United States)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities, advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today, the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  7. Ceramics reinforced metal base composite coatings produced by CO II laser cladding

    Science.gov (United States)

    Yang, Xichen; Wang, Yu; Yang, Nan

    2008-03-01

    Due to the excellent performance in high strength, anti-temperature and anti-wear, ceramics reinforced metal base composite material was used in some important fields of aircraft, aerospace, automobile and defense. The traditional bulk metal base composite materials are the expensive cost, which is limited in its industrial application. Development of laser coating of ceramics reinforced metal base composite is very interesting in economy. This paper is focused on three laser cladding ceramics coatings of SiC particle /Al matrix , Al IIO 3 powder/ Al matrix and WC + Co/mild steel matrix. Powder particle sizes are of 10-60μm. Chemical contents of aluminum matrix are of 3.8-4.0% Cu, 1.2-1.8% Mg, 0.3-0.99% Mn and balance Al. 5KW CO II laser, 5 axes CNC table, JKF-6 type powder feeder and co-axis feeder nozzle are used in laser cladding. Microstructure and performance of laser composite coatings have been respectively examined with OM,SEM and X-ray diffraction. Its results are as follows : Microstructures of 3C-,6H- and 5H- SiC particles + Al + Al 4SiC 4 + Si in SiC/Al composite, hexagonal α-Al IIO 3 + cubic γ-Al IIO 3 + f.c.c Al in Al IIO 3 powder/ Al composite and original WC particles + separated WC particles + eutectic WC + γ-Co solid solution + W IIC particles in WC + Co/steel coatings are respectively recognized. New microstructures of 5H-SiC in SiC/Al composite, cubic γ-Al IIO 3 in Al IIO 3 composite and W IIC in WC + Co/ steel composite by laser cladding have been respectively observed.

  8. Seating load parameters impact on dental ceramic reinforcement conferred by cementation with resin-cements.

    LENUS (Irish Health Repository)

    Addison, Owen

    2010-09-01

    Cementation of all-ceramic restorations with resin-cements has been demonstrated to reduce the incidence of fracture in service. The aim was to investigate the influence of loading force and loading duration applied during cementation on the reinforcement conferred by a resin-cement on a leucite reinforced glass-ceramic.

  9. Bond strength durability of a resin composite on a reinforced ceramic using various repair systems

    NARCIS (Netherlands)

    Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Leite, Fabiola; Bottino, Marco Antonio

    2009-01-01

    Objectives. This study compared the durability of repair bond strength of a resin composite to a reinforced ceramic after three repair systems. Methods. Alumina-reinforced feldspathic ceramic blocks (Vitadur-alpha(R)) (N=30) were randomly divided into three groups according to the repair method: PR-

  10. Covalent and heterosupramolecular interaction of ceramic particles

    OpenAIRE

    Stieger, Gregor

    2002-01-01

    New concepts of particle interaction for the processing of ceramic powders are developed. They are based on chemical reactions either by heterosupramolecular or covalent interaction of proper reactants. For this the particles are functionalized so that they are able to undergo defined reactions with each other. A commercially available beta-cyclodextrin derivative, 3-chlor-5-sodium-hydroxyl-trianzinyl-beta-cyclodextrin, is covalently bound to the Si3N4 surface in an one step reaction. An effo...

  11. Processing and Material Characterization of Continuous Basalt Fiber Reinforced Ceramic Matrix Composites Using Polymer Derived Ceramics.

    Science.gov (United States)

    Cox, Sarah B.

    2014-01-01

    The need for high performance vehicles in the aerospace industry requires materials which can withstand high loads and high temperatures. New developments in launch pads and infrastructure must also be made to handle this intense environment with lightweight, reusable, structural materials. By using more functional materials, better performance can be seen in the launch environment, and launch vehicle designs which have not been previously used can be considered. The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer matrix composites can be used for temperatures up to 260C. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in the composites. In this study, continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. The oxyacetylene torch testing and three point bend testing have been performed on test panels and the test results are presented.

  12. Passive vibration damping of carbon fiber reinforced plastic with PZT particles and SMA powder

    Science.gov (United States)

    Jung, Jaemin; Lee, Woo Il; Lee, Dasom; Park, Sungho; Moon, Sungnam

    2016-04-01

    Carbon fiber reinforced plastic (CFRP) has been used various industrial fields, because of high strength, light weight, corrosion resistance and other properties. In this study, lead zirconate titanate (PZT) ceramic particles which is one of typical piezoelectric material and shape memory alloy powder dispersed in CFRP laminate in order to improve the vibration damping by dissipating vibration energy quickly. The loss factor (tanδ) is measured in Dynamic mechanical analyzer (DMA) which is used to measure the viscoelastic behavior of a material to verify the change in vibration damping. The results show that there exists difference on vibration damping ability between CFRP with PZT ceramic particles and CFRP with SMA powder.

  13. Modeling oxidation damage of continuous fiber reinforced ceramic matrix composites

    Institute of Scientific and Technical Information of China (English)

    Cheng-Peng Yang; Gui-Qiong Jiao; Bo Wang

    2011-01-01

    For fiber reinforced ceramic matrix composites (CMCs), oxidation of the constituents is a very important damage type for high temperature applications. During the oxidizing process, the pyrolytic carbon interphase gradually recesses from the crack site in the axial direction of the fiber into the interior of the material. Carbon fiber usually presents notch-like or local neck-shrink oxidation phenomenon, causing strength degradation. But, the reason for SiC fiber degradation is the flaw growth mechanism on its surface. A micromechanical model based on the above mechanisms was established to simulate the mechanical properties of CMCs after high temperature oxidation. The statistic and shearlag theory were applied and the calculation expressions for retained tensile modulus and strength were deduced, respectively. Meanwhile, the interphase recession and fiber strength degradation were considered. And then, the model was validated by application to a C/SiC composite.

  14. In-situ Formation of Reinforcement Phases in Ultra High Temperature Ceramic Composites

    Science.gov (United States)

    Stackpoole, Margaret M (Inventor); Gasch, Matthew J (Inventor); Olson, Michael W (Inventor); Hamby, Ian W. (Inventor); Johnson, Sylvia M (Inventor)

    2013-01-01

    A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB.sub.2, ZrB.sub.2 or other metal boride, carbide, nitride, etc., surrounded by a uniform distribution of acicular high aspect ratio reinforcement ceramic rods or whiskers, such as of SiC, is formed from uniformly mixing a powder of the UHTC material and a pre-ceramic polymer selected to form the desired reinforcement species, then thermally consolidating the mixture by hot pressing. The acicular reinforcement rods may make up from 5 to 30 vol % of the resulting microstructure.

  15. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    International Nuclear Information System (INIS)

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating

  16. Creep Forming of Carbon-Reinforced Ceramic-Matrix Composites

    Science.gov (United States)

    Vaughn, Wallace L.; Scotti, Stephan J.; Ashe, Melissa P.; Connolly, Liz

    2007-01-01

    A set of lecture slides describes an investigation of creep forming as a means of imparting desired curvatures to initially flat stock plates of carbon-reinforced ceramic-matrix composite (C-CMC) materials. The investigation is apparently part of a continuing effort to develop improved means of applying small CCMC repair patches to reinforced carbon-carbon leading edges of aerospace vehicles (e.g., space shuttles) prior to re-entry into the atmosphere of the Earth. According to one of the slides, creep forming would be an intermediate step in a process that would yield a fully densified, finished C-CMC part having a desired size and shape (the other steps would include preliminary machining, finish machining, densification by chemical vapor infiltration, and final coating). The investigation included experiments in which C-CMC disks were creep-formed by heating them to unspecified high temperatures for time intervals of the order of 1 hour while they were clamped into single- and double-curvature graphite molds. The creep-formed disks were coated with an oxidation- protection material, then subjected to arc-jet tests, in which the disks exhibited no deterioration after exposure to high-temperature test conditions lasting 490 seconds.

  17. Application of ceramic short fiber reinforced Al alloy matrix composite on piston for internal combustion engines

    OpenAIRE

    Wu Shenqing; Li Jun

    2010-01-01

    The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced are...

  18. Damage analysis of the ceramic reinforced steel matrix composites sheets: experimental and numerical study

    Directory of Open Access Journals (Sweden)

    E. Bayraktar

    2011-11-01

    Full Text Available Purpose: of this paper reports damage analysis of TiB2 (ceramic particles reinforced steel matrix composite sheets. This new steel composite receives much attention as potential structural materials due to their high specific strength and stiffness. The goal of the research described in this paper is to study the usage of this new steel family in the manufacture of light structures.Design/methodology/approach: therefore in this study is focused to the titanium diboride TiB2 reinforced steel matrix composite sheets that they were characterized by optical and scanning electron microscopes after the mechanical tests carried out on the base metal and welded specimens under dynamic and static test conditions.Findings: The non homogeneity of the structure in this type of composites makes deeply complexity of their numerical and analytical modelling to predict their damage during the loading. For example, the interfaces essentially play a key role in determining mechanical and physical properties. For this reason, a Finite Element (FEM analysis is used for modelling to simulate the macroscopic behaviour of this material, taking into account the relevant microscopic scales.Practical implications: defined in this research is based on the impact dynamic behaviour of this steel sheets by using a special impact tensile test developed formerly that all details were published in this journal. This type of test gives more comprehensible information about special steel sheets (welded or base metal in case of dynamic crash conditions.Originality/value: The present research gives detail information on the new steel matrix composite sheets reinforced TiB2 ceramic particles. This new composite was developed by ARCELOR research group and impact dynamic behaviour and weldability of the welded parts and base metals from this composite steel are discussed here in order to give practical and useful solution for industrial applications.

  19. ECAP – New consolidation method for production of aluminium matrix composites with ceramic reinforcement

    Directory of Open Access Journals (Sweden)

    Mateja Šnajdar Musa

    2013-06-01

    Full Text Available Aluminium based metal matrix composites are rapidly developing group of materials due to their unique combination of properties that include low weight, elevated strength, improved wear and corrosion resistance and relatively good ductility. This combination of properties is a result of mixing two groups of materials with rather different properties with aluminium as ductile matrix and different oxides and carbides added as reinforcement. Al2O3, SiC and ZrO2 are the most popular choices of reinforcement material. One of the most common methods for producing this type of metal matrix composites is powder metallurgy since it has many variations and also is relatively low-cost method. Many different techniques of compacting aluminium and ceramic powders have been previously investigated. Among those techniques equal channel angular pressing (ECAP stands out due to its beneficial influence on the main problem that arises during powder compaction and that is a non-uniform distribution of reinforcement particles. This paper gives an overview on ECAP method principles, advantages and produced powder composite properties.

  20. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    International Nuclear Information System (INIS)

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  1. Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic : The effect of surface conditioning

    NARCIS (Netherlands)

    Amaral, R; Ozcan, M; Bottino, MA; Valandro, LF

    2006-01-01

    Objectives. This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Methods. Thirty blocks (5 x 5 x 4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR, VI

  2. Bond strength of a resin cement to high-alumina and zirconia-reinforced ceramics : The effect of surface conditioning

    NARCIS (Netherlands)

    Felipe Valandro, Luiz; Ozcan, Mutlu; Bottino, Marco Cicero; Bottino, Marco Antonio; Scotti, Roberto; Della Bona, Alvaro

    2006-01-01

    Purpose: The aim of this study was to evaluate the effect of two surface conditioning methods on the microtensile bond strength of a resin cement to three high-strength core ceramics: high alumina-based (In-Ceram Alumina, Procera AllCeram) and zirconia-reinforced alumina-based (in-Ceram Zirconia) ce

  3. Structure and properties of ceramic preforms based on Al2O3 particles

    OpenAIRE

    L.A. Dobrzański; M. Kremzer; Nagel, A.

    2009-01-01

    Purpose: The main goal of this project is to elaborate and optimize the method of manufacturing the porous, ceramic preforms based on Al2O3 particles used as the reinforcement in order to produce modern metal matrix composites by pressure infiltration method with liquid metal alloys.Design/methodology/approach: Ceramic preforms were manufactured by the sintering method of Al2O3 powder with addition of pore forming agent. The preform material consists of powder Alcoa Al2O3 CL 2500, however, as...

  4. Manufacturing of aluminium matrix composite materials reinforced by Al2O3 particles

    OpenAIRE

    A. Włodarczyk-Fligier; L.A. Dobrzański; M. Kremzer; M. Adamiak

    2008-01-01

    Purpose: The purpose of the paper is to show and compare of modern method composite materials with aluminium alloy matrix reinforced by Al2O3 particles manufacturing.Design/methodology/approach: Material for investigation was manufactured by two methods: powder metallurgy (consolidation, pressing, hot extrusion of powder mixtures of aluminium EN AW-AlCu4Mg1(A) and ceramic particles Al2O3) and pressure infiltration of porous performs by liquid alloy EN AC AlSi12 (performs were prepared by sint...

  5. Reinforcement of precursor-derived Si-(B-)C-N ceramics with carbon nanotubes

    OpenAIRE

    Katsuda, Yuji

    2005-01-01

    Incorporation of carbon nanotubes (CNTs) into the precursor-derived Si-(B-)C-N ceramics has been investigated for the reinforcement of the materials. Different types of CNTs consisting of multi-wall (MW) and single-wall (SW) were examined as the reinforcement of the Si-(B-)C-N ceramics to make a comparison of the effect. Mechanical properties demonstrated in the Si-(B-)C-N/CNT nanocomposites have been discussed in connection with their microstructural features characterized by scanning electr...

  6. Identification of effective properties of particle reinforced composite materials

    OpenAIRE

    Kushnevsky, V.; Morachkovsky, O.; Altenbach, H.

    1998-01-01

    For the determination of effective elastic properties an energy averaging procedure has been used for particle reinforced composite materials. This procedure is based on finite element calculations of the deformation energy of a characteristic volume element. The proposed approach allows the determination of effective properties of particle reinforced composite with acceptable precision. The calculated effective properties of the composite are found in range between upper and lower Hashin-Sht...

  7. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic.

    Science.gov (United States)

    Rinke, Sven; Pabel, Anne-Kathrin; Rödiger, Matthias; Ziebolz, Dirk

    2016-01-01

    The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS) ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM) of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa), optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow. PMID:27042362

  8. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    Directory of Open Access Journals (Sweden)

    Sven Rinke

    2016-01-01

    Full Text Available The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa, optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow.

  9. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    Science.gov (United States)

    Pabel, Anne-Kathrin; Rödiger, Matthias

    2016-01-01

    The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS) ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM) of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa), optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow. PMID:27042362

  10. Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow

    Directory of Open Access Journals (Sweden)

    Sven Rinke

    2015-01-01

    Full Text Available This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa, excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow.

  11. Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow.

    Science.gov (United States)

    Rinke, Sven; Rödiger, Matthias; Ziebolz, Dirk; Schmidt, Anne-Kathrin

    2015-01-01

    This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS) ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa), excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow. PMID:26509088

  12. Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow

    Science.gov (United States)

    Rinke, Sven; Rödiger, Matthias; Ziebolz, Dirk; Schmidt, Anne-Kathrin

    2015-01-01

    This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS) ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa), excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow. PMID:26509088

  13. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    OpenAIRE

    Sven Rinke; Anne-Kathrin Pabel; Matthias Rödiger; Dirk Ziebolz

    2016-01-01

    The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS) ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM) of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa), optimum polishing characteristics, and excellent optical prop...

  14. The influence of reinforcing particles on mechanical and tribological properties and microstructure of the steel-TiB2 composites

    OpenAIRE

    I. Sulima; L. Jaworska; P. Wyżga; M. Perek-Nowak

    2011-01-01

    Purpose: The present work aims to investigate the effect of the reinforcing ceramic particles on the mechanical and tribological properties and microstructure of the steel-TiB2 composites.Design/methodology/approach: The austenitic AISI316L stainless steel reinforced with 10 vol.% and 20 vol.% TiB2 particles was produced using the high temperature-high pressure (HT-HP) method. The sintering process was carried out at pressure of 7.0±0.2 GPa and temperature of 1200°C for 60 seconds. Density of...

  15. Particle-induced amorphization complex ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R.C.; Wang, Lu-Min

    1996-02-16

    The presently funded three-year research program, supported by the Division of Materials Sciences of the Office of Basic Energy Sciences, was initiated on August 1, 1993; during the period in which the grant will have been active, $249,561 of support have been provided to date with an additional $79,723 to be spent during the third, final year (ending July 30, 1996). The primary purpose of the program is to develop an understanding of heavy-particle radiation effects -- {alpha}-recoil nuclei, fission fragments, ion-irradiations -- on ceramic materials and the thermal annealing mechanisms by which crystallinity might be restored. During the past two years, we have completed major studies on zircon (ZrSiO{sub 4}), olivine (Mg{sub 2}SiO{sub 4} and ten other compositions), spinel (MgAl{sub 2}O{sub 4} and four other compositions), and silica polymorphs (quartz, coesite and stishovite), as well as berlinite (AlPO{sub 4}) which is isomorphous with quartz. In addition, based on the above research, we propose the use of zircon as a host phase for the immobilization of plutonium resulting from weapons dismantlement.

  16. Fiber reinforced glasses and glass-ceramics for high performance applications

    Science.gov (United States)

    Prewo, K. M.; Brennan, J. J.; Layden, G. K.

    1986-01-01

    The development of fiber reinforced glass and glass-ceramic matrix composites is described. The general concepts involved in composite fabrication and resultant composite properties are given for a broad range of fiber and matrix combinations. It is shown that composite materials can be tailored to achieve high levels of toughness, strength, and elastic stiffness, as well as wear resistance and dimensional stability.

  17. Selected mechanical properties of aluminum composite materials reinforced with SiC particles

    Directory of Open Access Journals (Sweden)

    A. Kurzawa

    2008-07-01

    Full Text Available This work presents the results of research concerning influence of ceramic particles’ content of silicon carbide on selected mechanical properties of type AW-AlCu4Mg2Mn - SiC composite materials. Composites produced of SiC particles with pressure infiltration method of porous preform and subject to hot plastic forming in the form of open die forging were investigated. The experimental samples contained from 5% up to 45% of reinforcing SiC particles of 8÷10μm diameter. Studies of strength properties demonstrated that the best results, in case of tensile strength as well as offset yield strength, might be obtained while applying reinforcement in the amount of 20-25% vol. of SiC. Application of higher than 25% vol. contents of reinforcing particles leads to gradual strength loss. The investigated composites were characterized by very high functional properties, such as hardness and abrasive wear resistance, whose values increase strongly with the increase of reinforcement amount. The presented results of the experiments shall allow for a more precise component selection of composite materials at the stage of planning and design of their properties.

  18. Ensuring near-optimum homogeneity and densification levels in nano-reinforced ceramics

    Science.gov (United States)

    Dassios, Konstantinos G.; Barkoula, Nektaria-Marianthi; Alafogianni, Panagiota; Bonnefont, Guillaume; Fantozzi, Gilbert; Matikas, Theodore E.

    2016-04-01

    The development of a new generation of high temperature ceramic materials for aerospace applications, reinforced at a scale closer to the molecular level and three orders of magnitude less than conventional fibrous reinforcements, by embedded carbon nanotubes, has recently emerged as a uniquely challenging scientific effort. The properties of such materials depend strongly on two main factors: i) the homogeneity of the dispersion of the hydrophobic medium throughout the ceramic volume and ii) the ultimate density of the resultant product after sintering of the green body at the high-temperatures and pressures required for ceramic consolidation. The present works reports the establishment of two independent experimental strategies which ensure achievement of near perfect levels of tube dispersion homogeneity and fully dense final products. The proposed methodologies are validated across non-destructive evaluation data of materials performance.

  19. Method of making carbon fiber-carbon matrix reinforced ceramic composites

    Science.gov (United States)

    Williams, Brian (Inventor); Benander, Robert (Inventor)

    2007-01-01

    A method of making a carbon fiber-carbon matrix reinforced ceramic composite wherein the result is a carbon fiber-carbon matrix reinforcement is embedded within a ceramic matrix. The ceramic matrix does not penetrate into the carbon fiber-carbon matrix reinforcement to any significant degree. The carbide matrix is a formed in situ solid carbide of at least one metal having a melting point above about 1850 degrees centigrade. At least when the composite is intended to operate between approximately 1500 and 2000 degrees centigrade for extended periods of time the solid carbide with the embedded reinforcement is formed first by reaction infiltration. Molten silicon is then diffused into the carbide. The molten silicon diffuses preferentially into the carbide matrix but not to any significant degree into the carbon-carbon reinforcement. Where the composite is intended to operate between approximately 2000 and 2700 degrees centigrade for extended periods of time such diffusion of molten silicon into the carbide is optional and generally preferred, but not essential.

  20. Mechanical behavior and properties of fiber reinforced ceramic matrix composites for high temperature use

    Institute of Scientific and Technical Information of China (English)

    Chongdu Cho; Qiang Pan; Sangkyo Lee

    2007-01-01

    Ceramics can keep their mechanical characteristics up to 2 000℃ or higher.In this paper,A model to predict ultimate strength of continuous fiber-reinforced brittle matrix composites is developed.A statistical theory for the strength of a uni-axially fiber-reinforced brittle matrix composite is presented.Also a semi-empirical frictional heating method for estimating in-situ interfacial shear in fiber-reinforced ceramic matrix composites was improved.Local uneven fiber packing variation as well as uneven micro-damage during fatigue can be expected to have effects on the composites:generation of frictional heating,thermal gradients,and residual stresses around local fiber breaks.This study examined those engineering interests by the finite element method.

  1. Preparation and characterization of resin-derived carbon foams reinforced by hollow ceramic microspheres

    International Nuclear Information System (INIS)

    Carbon foam materials were prepared with phenolic resole resin as precursor and hollow ceramic microspheres as reinforcement. The resultant carbon foams had a bulk density of between 0.22 and 0.27 g/cm3. Analysis of scanning electron micrographs indicated that the cells were mainly open with incomplete cell membranes, and the hollow ceramic microspheres were located in the junctions. Compression test results showed that the carbon foams with 1 wt% hollow ceramic microspheres exhibited the highest compressive strength (7.76 MPa). Thermal conductivity measurements revealed that the introduction of hollow ceramic microspheres improved the thermal insulating property. The thermal conductivity of carbon foams ranged from 0.11 to 0.25 W m-1 K-1 at room temperature, which makes carbon foams a prime choice for thermal insulation.

  2. Application of ceramic short fiber reinforced Al alloy matrix composite on piston for internal combustion engines

    Directory of Open Access Journals (Sweden)

    Wu Shenqing

    2010-11-01

    Full Text Available The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced areas, low reject rate and good technical tolerance. As a new kind of piston material, it has been used for mass production of about 400,000 pieces of automobile engines piston. China has become one of a few countries in which aluminum alloy matrix composite materials have been used in automobile industry and attained industrialization.

  3. Structure and properties of ceramic preforms based on Al2O3 particles

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2009-07-01

    Full Text Available Purpose: The main goal of this project is to elaborate and optimize the method of manufacturing the porous, ceramic preforms based on Al2O3 particles used as the reinforcement in order to produce modern metal matrix composites by pressure infiltration method with liquid metal alloys.Design/methodology/approach: Ceramic preforms were manufactured by the sintering method of Al2O3 powder with addition of pore forming agent. The preform material consists of powder Alcoa Al2O3 CL 2500, however, as the forming factor of the structure of canals and pores inside the ceramic, agglomerated framework the carbon fibres Sigrafil C10 M250 UNS were used. The addition of carbon fibres was 30, 40 and 50% of weight. The TGA analysis of carbon fibres has been made. The investigations of the structure of powder Al2O3 Alcoa CL 2500, the used carbon fibres and the obtained ceramic preforms on the scanning electron microscope (SEM have been made. The measurement of permeability of the obtained materials on the specially designed station has also been made.Findings: The obtained preforms are characterized by volumetric participation of ceramic phase of 15-31%, what is the result of differential addition of the pores forming agent, and the high permeability indicates on “the open porosity”.Research limitations/implications: The basic limit of the mentioned method is the possibility of obtaining preforms of porosity less than 85%, where in case of using the ceramic fibres the pores can be more than 90% of material volumetric.Practical implications: The manufactured ceramic preforms are widely used as the reinforcement to produce the composite materials by the infiltration method. That method allows manufacturing the metal elements locally reinforced and the near-net shape composite products.Originality/value: The received results show the possibility of obtaining the new preforms being the cheaper alternative for semi-finished products based on the ceramic fibres and

  4. Recent advances in understanding the reinforcing ability and mechanism of carbon nanotubes in ceramic matrix composites

    International Nuclear Information System (INIS)

    Since the discovery of carbon nanotubes (CNTs), commonly referred to as ultimate reinforcement, the main purpose for fabricating CNT–ceramic matrix composites has been mainly to improve the fracture toughness and strength of the ceramic matrix materials. However, there have been many studies reporting marginal improvements or even the degradation of mechanical properties. On the other hand, those studies claiming noticeable toughening measured using indentation, which is an indirect/unreliable characterization method, have not demonstrated the responsible mechanisms applicable to the nanoscale, flexible CNTs; instead, those studies proposed those classical methods applicable to microscale fiber/whisker reinforced ceramics without showing any convincing evidence of load transfer to the CNTs. Therefore, the ability of CNTs to directly improve the macroscopic mechanical properties of structural ceramics has been strongly questioned and debated in the last ten years. In order to properly discuss the reinforcing ability (and possible mechanisms) of CNTs in a ceramic host material, there are three fundamental questions to our knowledge at both the nanoscale and macroscale levels that need to be addressed: (1) does the intrinsic load-bearing ability of CNTs change when embedded in a ceramic host matrix?; (2) when there is an intimate atomic-level interface without any chemical reaction with the matrix, could one expect any load transfer to the CNTs along with effective load bearing by them during crack propagation?; and (3) considering their nanometer-scale dimensions, flexibility and radial softness, are the CNTs able to improve the mechanical properties of the host ceramic matrix at the macroscale when individually, intimately and uniformly dispersed? If so, how? Also, what is the effect of CNT concentration in such a defect-free composite system? Here, we briefly review the recent studies addressing the above fundamental questions. In particular, we discuss the new

  5. Elastic properties of silica-silica continuous fibre-reinforced, ceramic matrix composites

    International Nuclear Information System (INIS)

    Ambient and elevated temperature elastic properties of silica-silica ceramic fibre-reinforced, ceramic-matrix composites (silica-silica CFCCs), obtained using resonance beam technique, have been reported and discussed. The composite exhibits in-plane isotropy and through-thickness anisotropy in the elastic properties at ambient temperatures and increasing elastic moduli with increasing test temperature. The latter results are attributable to the change in the nature of atomic bonding of the silica material up to about 1173 K and further increase in moduli with temperature is due to the combined effects of devitrification and densification due to sintering

  6. Mechanical Reinforcement and Piezoelectric Properties of PZT Ceramics Embedded with Nano-Crystalline

    International Nuclear Information System (INIS)

    The double-scale lead zirconate titanate (PZT) piezoelectric ceramics were prepared by the solid state processing with PZT nano-crystalline and micro-powder. The microstructures, electrical and mechanical properties of the double-scale PZT are investigated. All the sintered ceramics exhibit a single perovskite structure and the grain size of the double-scale PZT reduces due to the incorporation of PZT nano-crystalline. Compared to normal PZT, the mechanical properties increase significantly and the piezoelectric properties decrease slightly. Mechanisms responsible for the reinforcement of the double-scale PZT are discussed

  7. Approach to microstructure-behavior relationships for ceramic matrix composites reinforced by continuous fibers

    OpenAIRE

    Lamon Jacques

    2015-01-01

    Ceramic matrix composites (CMCs) reinforced with continuous fibers exhibit several features that differentiate them from homogeneous unreinforced materials. The microstructure consists of various distinct constituents: fibres, matrix, and fiber/matrix interfaces or interphases. Several entities at micro- and mesoscopic length scales can be defined depending on fiber arrangement. Furthermore, the CMCs contain flaw populations that govern matrix cracking and fiber failures. The paper describes ...

  8. Colloidal processing of Fe-based metalceramic composites with high content of ceramic reinforcement

    OpenAIRE

    Escribano, J.A.; Ferrari, Begoña; Alvaredo Olmos, Paula; Gordo Odériz, Elena; Sánchez-Herencia, A. J.

    2013-01-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases...

  9. Low Cost Fabrication of Silicon Carbide Based Ceramics and Fiber Reinforced Composites

    Science.gov (United States)

    Singh, M.; Levine, S. R.

    1995-01-01

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC's) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  10. Comparative investigation of creep behavior of ceramic fiber-reinforced alumina and silica aerogel

    International Nuclear Information System (INIS)

    Ambient and high temperature creep experiments at constant stresses of 0.05 MPa and 0.2 MPa were conducted on a ceramic fiber-reinforced alumina aerogel. Experimental results show that at low temperature (below 300 °C), there is no significant creep phenomenon at low stress level (0.05 MPa), but time-dependent creep deformation is found at high stress level (0.2 MPa) for the material. Scanning Electron Microscope (SEM) analysis was also conducted to understand the micro mechanism of the creep behavior. Crack initiation and propagation in matrix are the key factors that change the creep property. Comparative investigation of creep properties was also carried out between ceramic fiber-reinforced alumina and silica aerogel. Finally the application prospect of the two composites was discussed. The result shows that alumina aerogel has excellent creep resistance, thermal stability and heat insulation properties at high temperature (above 800 °C), and it has a good application prospect in high temperature insulation fields, while the ceramic fiber-reinforced silica aerogel, limited by the sintering and poor creep resistance under high temperature, is more suitable for low temperature (below 600 °C) insulation field

  11. Comparative investigation of creep behavior of ceramic fiber-reinforced alumina and silica aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaoguang; Wei, Jing [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Shi, Duoqi, E-mail: shdq@buaa.edu.cn [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Sun, Yantao; Lv, Shuangqi [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Feng, Jian; Jiang, Yonggang [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China)

    2014-07-15

    Ambient and high temperature creep experiments at constant stresses of 0.05 MPa and 0.2 MPa were conducted on a ceramic fiber-reinforced alumina aerogel. Experimental results show that at low temperature (below 300 °C), there is no significant creep phenomenon at low stress level (0.05 MPa), but time-dependent creep deformation is found at high stress level (0.2 MPa) for the material. Scanning Electron Microscope (SEM) analysis was also conducted to understand the micro mechanism of the creep behavior. Crack initiation and propagation in matrix are the key factors that change the creep property. Comparative investigation of creep properties was also carried out between ceramic fiber-reinforced alumina and silica aerogel. Finally the application prospect of the two composites was discussed. The result shows that alumina aerogel has excellent creep resistance, thermal stability and heat insulation properties at high temperature (above 800 °C), and it has a good application prospect in high temperature insulation fields, while the ceramic fiber-reinforced silica aerogel, limited by the sintering and poor creep resistance under high temperature, is more suitable for low temperature (below 600 °C) insulation field.

  12. Intraoral repair of all ceramic fixed partial denture utilizing preimpregnated fiber reinforced composite.

    Science.gov (United States)

    Turkaslan, Süha; Tezvergil-Mutluay, Arzu

    2008-01-01

    All ceramic fixed partial dentures (FPD)s exhibit enhanced biocompatibility and esthetics as compared to metal-ceramic restorations. However, framework fractures are frequently reported especially when the connector dimensions are inadequate to withstand the high tensile stresses. The repair of the failed connector would be desirable rather than the complete removal and renewal since the latter is an expensive and time consuming procedure. Furthermore, the replacement or removal of the restoration for extra-oral repair purposes might increase the risk of destroying the entire restoration or damaging the abutment teeth during the removal. This article presents a direct intra-oral method that may be used to repair the connector fractures of all-ceramic FPDs which are otherwise clinically satisfactory. In the present technique, the connector is reconstructed intraorally utilizing composite resin restorative material reinforced with E-glass-fiber. PMID:19212511

  13. Reciprocal sliding wear of SiC particle-reinforced Al-Cu aluminium matrix composites against stainless steel, high speed tool steel and ceramics. Pt. 2. Wear mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Bai Mingwu [Lab. of Solid Lubrication, Lanzhou Inst. of Chemical Physics (China); Xue Qunji [Lab. of Solid Lubrication, Lanzhou Inst. of Chemical Physics (China); Guo Huifang [Inst. of Powder Metallurgy, Central-South Univ. of Technology, Changsha (China)

    1996-06-01

    The friction and wear of Al-Cu-SiC aluminium matrix composite pins dry sliding against 4Cr13, W{sub 18}Cr{sub 4}V and Si{sub 3}N{sub 4} (SN) ceramic blocks were investigated in a reciprocal friction test machine under applied loads of 20-175 N and reciprocal speeds of 0.075-1.2 m s{sup -1}. The worn surface morphology was analysed to clarify the wear mechanisms. Wear mechanism maps were constructed to elucidate the effects of test condition such as applied load, reciprocal speed and counterface materials on the wear mode and wear mechanism transition. Wear models were proposed to explain the experimental phenomena based on the characterization studies. (orig.)

  14. PARTICULATE SIZE EFFECTS IN THE PARTICLE-REINFORCED METAL-MATRIX COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    魏悦广

    2001-01-01

    The influences of particle size on the mechanical properties of the particulate metal matrix composite are obviously displayed in the experimental observations. However, the phenomenon can not be predicted directly using the conventional elastic-plastic theory. It is because that no length scale parameters are involved in the conventional theory. In the present research, using the strain gradient plasticity theory, a systematic research of the particle size effect in the particulate metal matrix composite is carried out. The roles of many composite factors, such as: the particle size, the Young's modulus of the particle, the particle aspect ratio and volume fraction, as well as the plastic strain hardening exponent of the matrix material,are studied in detail. In order to obtain a general understanding for the composite behavior, two kinds of particle shapes, ellipsoid and cylinder, are considered to check the strength dependence of the smooth or non-smooth particle surface. Finally,the prediction results will be applied to the several experiments about the ceramic particle-reinforced metal-matrix composites. The material length scale parameter is predicted.

  15. Jet Electrochemical Machining of Particle Reinforced Aluminum Matrix Composites with Different Neutral Electrolytes

    Science.gov (United States)

    Hackert-Oschätzchen, M.; Lehnert, N.; Martin, A.; Schubert, A.

    2016-03-01

    Conventional mechanical machining of particle reinforced aluminum matrix composites (AMCs) is challenging because the hard ceramic particles in the soft aluminum matrix lead to an increased tool wear. Furthermore, the mechanical and thermal impact during conventional machining affects the microstructure of the AMCs. Electrochemical machining (ECM) is an alternative method to machine AMCs. Based on anodic dissolution, ECM has a slight influence on the work piece material structure and is independent of material strength and hardness. So the microstructure of the work piece remains unaffected. One method of ECM is electrochemical machining with continuous electrolytic free jet (Jet-ECM). Hereby the electrochemical removal is localized by the geometry of the electrolyte jet. By moving the electrolyte jet micro-structures and microgeometries can be generated quickly and flexibly in metallic parts [1]. Another advantage of Jet-ECM is the low consumption of electrolyte which allows an easy and inexpensive change of electrolyte for investigations with different types of electrolyte. In this study AMCs reinforced with different amounts of SiC-particles are machined with two pH-neutral electrolytes using Jet-ECM. The results provide information about the suitability of the selected electrolytes for the machining of AMCs. In addition, the influence of the particle content on the electrochemical removal result will be evaluated.

  16. Nanoindentation of Za-27 Alloy Based Nanocomposites Reinforced with Al2O3 Particles

    Directory of Open Access Journals (Sweden)

    D. Džunić

    2015-12-01

    Full Text Available Nanoindentation has been widely used for material mechanical characterization. In this study, nanocompozite of ZA-27 alloy matrix reinforced with different volume fractions of nanometric Al2O3 ceramic particles ranging from 0 to 5 %, were produces using compocasting technique. Nanoindentation tests were performed using Berkovich three sided diamond pyramid, with maximum load of 100 mN and maximum load holding time of 15 s. Indentation imprints were investigated using optical and atomic force microscopy (AFM. Average particle size was 20-30 nm. Nanoindentation tests showed that nanocomposites have higher values of hardness and lower values of elastic modulus in comparison to the ZA-27 matrix alloy. Obtained results have different values in comparison to the theoretical investigations.

  17. Laser surface forming of AlCoCrCuFeNi particle reinforced AZ91D matrix composites

    Science.gov (United States)

    Meng, Guanghui; Yue, T. M.; Lin, Xin; Yang, Haiou; Xie, Hui; Ding, Xu

    2015-07-01

    Traditionally, the laser melt injection (LMI) technique can only be used for forming ceramic particles reinforced metal matrix composites (MMCs) for enhancing surface properties of lightweight engineering materials. In this research, the LMI method was employed to form metal particles reinforced MMCs on AZ91D instead. This was viable because of the unique properties of the AlCoCrCuFeNi high-entropy alloy (HEA) metal particles used. The large difference in melting point between the HEA and the substrate material (AZ91D), and the limited reaction and the lack of fusion between the HEA and Mg have made it possible that a metal particles reinforced AZ91D composite material was produced. The reason of limited reaction was considered mainly due to the relatively high mixing enthalpy between the HEA constituent elements and Mg. Although there was some melting occurred at the particles surface with some solute segregation found in the vicinity close to the surface, intermetallic compounds were not observed. With regard to the wear resistance of the MMCs, it was found that when the volume fraction of the reinforcement phase, i.e. the HEA particles, reached about 0.4, the wear volume loss of the coating was only one-seventh of that of the substrate material.

  18. Cytotoxicity evaluation of ceramic particles of different sizes and shapes.

    Science.gov (United States)

    Yamamoto, Akiko; Honma, Rieko; Sumita, Masae; Hanawa, Takao

    2004-02-01

    When artificial hip or knee joints are implanted in the human body, they release metallic, ceramic, and polymeric debris into the surrounding tissues. The toxicity of the released particles is of two types: chemical, caused by the released soluble ions and monomers, and mechanical, a result of mechanical stimulation produced by the insoluble particles. In this study, the cytotoxicity of particles of TiO2, Al2O3, ZrO2, Si3N4, and SiC for murine fibroblasts and macrophages were examined to evaluate just their mechanical toxicity because these particles are not expected to release soluble metal ions. Different sizes and shapes of TiO2 particles were used to evaluate the effect of size and shape on particle cytotoxicity. The results suggest that the cytotoxicity of ceramic particles does not depend on their chemical species. Cytotoxicity levels were lower than those of corresponding metal ions, indicating that the mechanical toxicity of particles is lower than the chemical toxicity of released soluble ions and monomers. The differences in size did not affect the mechanical toxicity of these particles. The dendritic particles had a higher cytotoxicity level for macrophages than did spindle and spheric particles. PMID:14704966

  19. Wetting in Al composites reinforced with SiC particles

    OpenAIRE

    A.C. Vieira; Rocha, L A; Gomes, J. R.

    2006-01-01

    Aluminium matrix composites have been wide used essentially due to the good relation between weight and mechanical resistance. To develop a ceramic particle/matrix interface with good characteristics, it is essential to control the interface reactivity, avoiding the formation of undesirable reaction products such as Al4C3. Essentially, there are three methods to prevent the Al4C3 formation: Si addition to Al matrix, coating of the SiC particles and to promote a passive oxidation of SiC pa...

  20. Microstructure, properties and application of YAl{sub 2} intermetallic compound as particle reinforcements

    Energy Technology Data Exchange (ETDEWEB)

    Li, N.; Zhang, Q.Q.; Niu, L.Y. [School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191 (China); Wu, G.Q., E-mail: guoqingwu@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100191 (China); Sha, W. [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom)

    2014-11-03

    An yttrium aluminum (YAl{sub 2}) intermetallic compound ingot was prepared in an induction furnace under vacuum. The microstructure of YAl{sub 2} ingot was characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. The load bearing response of YAl{sub 2} intermetallic was investigated and compared with SiC ceramic by indentation combined with optical microscopy and scanning electron microscopy. Additionally, the tensile properties of the Mg–Li matrix composites reinforced with ultrafine YAl{sub 2} particles fabricated by planet ball milling were tested. The results show that the intermetallic compound ingot in this experiment is composed of a main face-centered-cubic structure YAl{sub 2} phase, a small amount of YAl phase, and minor Y and Al-rich phases. YAl{sub 2} intermetallic compound has excellent stability and shows better capability in crack resistance than SiC ceramic. The YAl{sub 2} intermetallic compound has better deformation compatibility with the Mg–14Li–3Al matrix than SiC reinforcement with the matrix, which leads to the superior resistance to crack for YAl{sub 2p}/Mg–14Li–3Al composite compared to SiC{sub p}/Mg–14Li–3Al composite.

  1. Microstructure, properties and application of YAl2 intermetallic compound as particle reinforcements

    International Nuclear Information System (INIS)

    An yttrium aluminum (YAl2) intermetallic compound ingot was prepared in an induction furnace under vacuum. The microstructure of YAl2 ingot was characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. The load bearing response of YAl2 intermetallic was investigated and compared with SiC ceramic by indentation combined with optical microscopy and scanning electron microscopy. Additionally, the tensile properties of the Mg–Li matrix composites reinforced with ultrafine YAl2 particles fabricated by planet ball milling were tested. The results show that the intermetallic compound ingot in this experiment is composed of a main face-centered-cubic structure YAl2 phase, a small amount of YAl phase, and minor Y and Al-rich phases. YAl2 intermetallic compound has excellent stability and shows better capability in crack resistance than SiC ceramic. The YAl2 intermetallic compound has better deformation compatibility with the Mg–14Li–3Al matrix than SiC reinforcement with the matrix, which leads to the superior resistance to crack for YAl2p/Mg–14Li–3Al composite compared to SiCp/Mg–14Li–3Al composite

  2. 颗粒补强Al2O3/SiC/(W,Ti)C复相陶瓷刀具材料的氧化行为与强度特性%OXIDATION BEHAVIOR AND STRENGTH CHARACTERISTICS OF PARTICLE REINFORCED Al2O3/SiC/(W, Ti)C COMPOSITE CERAMIC TOOL MATERIALS

    Institute of Scientific and Technical Information of China (English)

    许崇海; 黄传真; 邓建新; 艾兴

    2001-01-01

    研究了颗粒补强Al2O3/SiC(W,Ti)C复相陶瓷刀具材料的氧化行为及其对材料抗弯强度的影响,结果表明:该材料在空气中静态氧化时的氧化增重符合抛物线规律随弥散相SiC和(W,Ti)C的增加,其氧化活化能有不同程度的降低.由于SiC的添加,使得氧化膜在高温下能以粘性流动的方式缓解残余应力,降低氧化速度,从而使得材料的抗氧化性能有所提高.此外,适当的氧化处理可使Al2O3/SiC/(W,Ti)C陶瓷刀具材料的抗弯强度得到提高.%Oxidation behavior of the particle reinforced Al2O3/SiC/(W, Ti)C composite ceramic tool materials has been studied in detail, as well as the effect of the oxidation on the flexural strength of the material. It is shown that the weight gains in the static oxidation of the material under air atmosphere obey the parabolic law. The energy of activation of the material decreases with the increase in the content of SiC and (W, Ti)C. Residual stresses in the oxidation film can be released with the form of the viscous flowing at high temperature. Therefore, the speed of the oxidation is lowered, and then the oxidation resistance of the material can be enhanced to some extent. It is found that the appropriate oxidation is effective for the improvement of the flexural strength of Al2O3/SiC/(W, Ti)C ceramic tool material.

  3. Dissolution studies of hydroxyapatite and glass-reinforced hydroxyapatite ceramics

    International Nuclear Information System (INIS)

    In the continuous agitation assays, glass-reinforced hydroxyapatite (GR-HA) was shown to form a calcium phosphate (CaP) layer, but hydroxyapatite (HA) only formed dispersed precipitates. The formation of this layer was first detected on the GR-HA with a 7.5% glass addition (7.5 GR-HA) after only 3 days of immersion in simulated body fluid (SBF). The time required for layer formation decreased as the amount of glass added to the HA increased. The dissolution rate of the materials followed a similar pattern, i.e. the dissolution rate for GR-HA was higher than for HA, and increased with the addition of glass. The immersion of 7.5 GR-HA in water showed almost linear dissolution kinetics over the immersion periods (3, 7, 15, 30 and 60 days). The concentration of calcium ions in solution and the scanning electron microscopy (SEM) analysis of the 7.5 GR-HA specimens immersed in water and in SBF revealed a clear competition between the material dissolution and the precipitation of a CaP phase. Fourier transformed infrared spectroscopy with alternated total reflectance (FTIR-ATR) analysis indicated that the CaP phase that formed during longer immersion times (30 and 60 days) could be a carbonate-substituted CaP precipitate. As expected from previous work, the GR-HA behavior in terms of its in vitro bioactivity is higher than HA because a homogeneous CaP layer is formed and the precipitation occurs faster. From the dissolution test and in accordance with the chemical composition of the samples, GR-HA was more soluble than HA

  4. Reinforcing and toughening alumina/titania ceramic composites with nano-dopants from nanostructured composite powders

    International Nuclear Information System (INIS)

    Nanostructured alumina/titania composite powders were prepared using nanosized alumina and titania doped with nanosized zirconia and ceria through ball-milling, spray drying and heat treating. The nanostructured reconstituted powders were then cool isostatic pressed and pressureless sintered into bulk ceramic composites. The phase constitution and microstructures of as-prepared ceramic composites were characterized by using X-ray diffractometer and scanning electron microscope. The mechanical properties of the ceramic composites were evaluated by Vickers hardness test, flexural strength test and fracture toughness test. The effects of nano-dopants and sintering temperatures on the microstructures and mechanical properties of the composites were investigated. It was found that nano-dopants had the effects of lowering sintering temperature, accelerating densification, reinforcing and toughening the composites. The maximum flexural strength, fracture toughness and Vickers hardness of the composites with nano-dopants were 51, 20 and 56% higher than that of the composites without nano-dopants. The reinforcing and toughening mechanisms are discussed in detail.

  5. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    Science.gov (United States)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  6. Laser cladding in-situ carbide particle reinforced Fe-based composite coatings with rare earth oxide addition

    Institute of Scientific and Technical Information of China (English)

    吴朝锋; 马明星; 刘文今; 钟敏霖; 张红军; 张伟明

    2009-01-01

    Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles.Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements,was favorable for the formation of in-situ synthesized carbide particles.In this paper,rare earth oxide(RE2O3) was added into t...

  7. Endocrown with Leucite-Reinforced Ceramic: Case of Restoration of Endodontically Treated Teeth

    Directory of Open Access Journals (Sweden)

    Leonardo Fernandes da Cunha

    2015-01-01

    Full Text Available A common problem encountered by dentists is the restorative treatment of nonvital teeth. When the pulp chamber presents appropriate conditions for retention, the endocrown is indicated. This monolithic, ceramic adhesive restoration is singularly used yet warrants wider recognition and use. The endocrown allows preservation of the tooth structure and is minimally invasive. Currently, this treatment option, of a core buildup and full coverage restoration, reduces tooth structure excessively. This treatment presents not only functional limitations but also aesthetic concerns. Recently, the VITA-PM9 system, a leucite-reinforced glass ceramic, has been increasingly used in a variety of clinical situations due to its satisfactory physical-mechanical and aesthetic properties. Therefore, the present study describes a case of surgical restoration of a nonvital tooth using the endocrown technique and the VITA-PM9.

  8. Method of producing a silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam P. (Inventor)

    1995-01-01

    A SrO-Al2O3-2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  9. Silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam (Inventor)

    1992-01-01

    A SrO-Al2O3 - 2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  10. Porosity characterization of fiber-reinforced ceramic matrix composite using synchrotron X-ray computed tomography

    Science.gov (United States)

    Zou, C.; Marrow, T. J.; Reinhard, C.; Li, B.; Zhang, C.; Wang, S.

    2016-03-01

    The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a "node-bond" geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9% for the composite, amid which there is about 7.1~ 9.3% closed micropores.

  11. Columnar-to-Equiaxed Transition in Metal-Matrix Composites Reinforced with Silicon Carbide Particles

    Directory of Open Access Journals (Sweden)

    Alicia E. Ares

    2013-01-01

    Full Text Available The present work is focused on the study of the effect of directional heat extraction on the silicon-carbide (SiC distribution in zinc-aluminum matrix composites (MMCs and on the columnar-to-equiaxed (CET position in directionally solidified samples. To this end, a ZA-27 alloy matrix was reinforced with ceramic particles of SiC and vertically directionally solidified. The cooling rates, temperature gradients, and interphase velocities were then measured, and their influence on the solidification microstructure of the MMCs was analyzed. The recalescence detected and measured during the equiaxed transition was of the order of 3.5°C to 1.1°C. The values of the temperature gradients reached a minimum during the CET and were even negative in most cases (between −3.89 K and 0.06 K. The interphase velocities varied between 0.07 mm/s and 0.44 mm/s at the transition. Also, the presence of ceramic particles in ZA-27 alloys affected the thermodynamic local conditions and the kinetics of nucleation, producing a finer microstructure.

  12. Finite Element Analysis of IPS –Empress II Ceramic Bridge Reinforced by Zirconia Bar

    Directory of Open Access Journals (Sweden)

    Allahyar Geramy

    2012-01-01

    Full Text Available Objective: The aim of this study was to determine the effect of trenched zirconia bar on the von Mises stress distribution of IPS –Empress II core ceramics.Material and Methods: The three-dimensional model including a three-unit bridge from the second premolar to the second molar was designed. The model was reinforced with zirconia bar (ZB, zirconia bar with vertical trench (VZB, and zirconia bar with horizontal trench (HZB (cross sections of these bars were circular. The model without zirconia bar was designed as the control. The bridges were loaded by 200 N and 500 N on the occlusal surface at the middle of the pontic component, and Von-Mises stresses were evaluated along a defined path.Result: In the connector area, VonMises stress in MPa were approximately identical in the specimens with ZB (at molar connector (MC: 4.75, and at premolar connector (PC: 6.40 and without ZB (MC: 5.50, PC: 6.68, and considerable differences were not recognized. Whereas, Von-Mises stress (MPa in the specimens with horizontal trenched Zirconia bar (HZB (MC: 3.91, PC: 2.44 and Vertical trenched Zirconia bar (VZB (MC: 2.53, PC: 2.56 was decreased considerably.Conclusion: Embeded trenched zirconia bar could reinforce IPS-Empress II at the connector area which is a main failure region in all ceramic fixed partial dentures.

  13. Silane primers rather than heat treatment contribute to adhesive bonding between tri-n-butylborane resin and a machinable leucite-reinforced ceramic

    OpenAIRE

    Sakai, Miyuki; Taira, Yohsuke; Sawase, Takashi

    2011-01-01

    The purpose of the present study was to evaluate the effects of silane primers with and without heat treatment on bonding between a resin and a leucite-reinforced ceramic (GN-Ceram). Six dental primers (GC Ceramic Primer, GP; Clearfl Ceramic Primer, CP; RelyX Ceramic Primer, RP; Tokuso Ceramic Primer, TP; Shofu Porcelain Primer, SP; and Porcelain Liner M, PM) and five experimental primers (MDS, MTS, MDES, MTES, and ATS) were evaluated. GN-Ceram specimen was primed, heated at 100°C for 60 min ...

  14. Preparation of metal-ceramic composites by sonochemical synthesis of metallic nano-particles and in-situ decoration on ceramic powders.

    Science.gov (United States)

    Poulia, A; Sakkas, P M; Kanellopoulou, D G; Sourkouni, G; Legros, C; Argirusis, Chr

    2016-07-01

    Copper and nickel nanoparticles were synthesized using reducing agents in the presence of direct high energy ultra-sonication. The metallic nanoparticles were decorated on various ceramic substrates (e.g. α-Al2O3, and TiO2) leading to metal reinforced ceramics with up to 45% metallic content. Different parameters, such as the amount of precursor material or the substrate, as well as the intensity of ultrasound were examined, in order to evaluate the percentage of final metallic decoration on the composite materials. All products were characterized by means of Inductively Coupled Plasma Spectroscopy in order to investigate the loading with metallic particles. X-ray Diffraction and Scanning Electron Microscopy were also used for further sample characterization. Selected samples were examined using Transmission Electron Microscopy, while finally, some of the powders synthesized, were densified by means of Spark Plasma Sintering, followed by a SEM/EDX examination and an estimation of their porosity. PMID:26964967

  15. Formation of carbon fiber-reinforced ceramic matrix composites with polysiloxane/silicon derived matrix

    International Nuclear Information System (INIS)

    A ceramic matrix for carbon fiber-reinforced ceramic matrix composites (CMCs) has been developed from poly(methylsilsesquioxane)/silicon mixtures, using a low-cost process. In this process the space in two-dimensional carbon fiber preform was filled with a slurry composed by Si powder dispersed into poly(methylsilsesquioxane)/trietoxysilane solutions. Three different volume ratio of Si:polymer were used to stack eight-harness plain weave of carbon fiber, forming laminates composites, which were pressed and cured up to 200 deg. C. The compact bodies were first pre-pyrolyzed at 1000 deg. C and then pyrolyzed at 1450 deg. C/2 h and 1500 deg. C/1 h. On pyrolysis, the polymer-filler mixture was converted to a multiphase ceramic matrix through reactions between Si, gaseous and solids products from the polymer degradation and the N2 atmosphere. Pyrolysis led to conversion of the initial matrix into silicon oxide (SiO2), silicon carbide (SiC) and silicon oxinitride (Si2ON2), though after pyrolysis at 1450 deg. C metallic silicon was still detected. With one cycle of infiltration the composite characteristics were followed by bulk density and open porosity measurements, X-ray diffraction, microscopy and mechanical testing

  16. Design and characterization of a carbon-nanotube-reinforced adhesive coating for piezoelectric ceramic discs

    International Nuclear Information System (INIS)

    The silver paste electrode of piezoelectric (PZT) ceramic discs has been shown to produce a weak interface bond between a bare PZT and its paste coating under a peeling force. In this work, an investigation was conducted to reinforce the bond with a high density array of oriented carbon nanotube nano-electrodes (CNTs-NEA), between a bare PZT ceramic and a metal substrate. The ensuing design and fabrication of a carbon-nanotube-coated piezoelectric disc (CPZT) is presented along with a study of the bondline integrity of a CPZT mounted on a hosting structure. The CPZT has its electrode silver paste coating replaced with a high density array of CNTs-NEA. Mechanical tests were performed to characterize the shear strength of the bondline between CPZT discs and the substrate. The test results were compared with shear strengths of the bondlines made of pure non-conductive adhesive and adhesive with randomly mixed CNTs. The comparison showed the oriented CNT coating on PZTs could significantly enhance the interfacial shear strength. Through the microscopic examination, it was evident that the ratio between the CNT length (Lc) and the bond thickness (H) significantly influenced the bond strength of CPZT discs. Three major interface microstructure types and their corresponding failure modes for specific Lc/H values were identified. The study also showed that failure did not occur along the interface between the PZT ceramic element and the CNT coating

  17. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced composite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of particle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  18. Micromechanics Fatigue Damage Analysis Modeling for Fabric Reinforced Ceramic Matrix Composites

    Science.gov (United States)

    Min, J. B.; Xue, D.; Shi, Y.

    2013-01-01

    A micromechanics analysis modeling method was developed to analyze the damage progression and fatigue failure of fabric reinforced composite structures, especially for the brittle ceramic matrix material composites. A repeating unit cell concept of fabric reinforced composites was used to represent the global composite structure. The thermal and mechanical properties of the repeating unit cell were considered as the same as those of the global composite structure. The three-phase micromechanics, the shear-lag, and the continuum fracture mechanics models were integrated with a statistical model in the repeating unit cell to predict the progressive damages and fatigue life of the composite structures. The global structure failure was defined as the loss of loading capability of the repeating unit cell, which depends on the stiffness reduction due to material slice failures and nonlinear material properties in the repeating unit cell. The present methodology is demonstrated with the analysis results evaluated through the experimental test performed with carbon fiber reinforced silicon carbide matrix plain weave composite specimens.

  19. Particle-induced amorphization of complex ceramics. Final report

    International Nuclear Information System (INIS)

    The crystalline-to-amorphous (c-a) phase transition is of fundamental importance. Particle irradiations provide an important, highly controlled means of investigating this phase transformation and the structure of the amorphous state. The interaction of heavy-particles with ceramics is complex because these materials have a wide range of structure types, complex compositions, and because chemical bonding is variable. Radiation damage and annealing can produce diverse results, but most commonly, single crystals become aperiodic or break down into a polycrystalline aggregate. The authors continued the studies of the transition from the periodic-to-aperiodic state in natural materials that have been damaged by α-recoil nuclei in the uranium and thorium decay series and in synthetic, analogous structures. The transition from the periodic to aperiodic state was followed by detailed x-ray diffraction analysis, in-situ irradiation/transmission electron microscopy, high resolution transmission electron microscopy, extended x-ray absorption fine structure spectroscopy/x-ray absorption near edge spectroscopy and other spectroscopic techniques. These studies were completed in conjunction with bulk irradiations that can be completed at Los Alamos National Laboratory or Sandia National Laboratories. Principal questions addressed in this research program included: (1) What is the process at the atomic level by which a ceramic material is transformed into a disordered or aperiodic state? (2) What are the controlling effects of structural topology, bond-type, dose rate, and irradiation temperature on the final state of the irradiated material? (3) What is the structure of the damaged material? (4) What are the mechanisms and kinetics for the annealing of interstitial and aggregate defects in these irradiated ceramic materials? (5) What general criteria may be applied to the prediction of amorphization in complex ceramics?

  20. Marginal adaptation of 1 fiber-reinforced composite and 2 all-ceramic inlay fixed partial denture systems

    OpenAIRE

    Monaco, Carlo; Krejci, Ivo; Bortolotto Ibarra, Tissiana; Perakis, Nikolaos; Ferrari,Marco; Scotti, Roberto

    2006-01-01

    The aim of this in vitro study was to evaluate the marginal adaptation and retention of inlay fixed partial dentures (IFPDs) made with 1 fiber-reinforced composite and 2 different ceramic materials using quantitative scanning electron microscope analysis after thermal cycling and mechanical loading, which simulated approximately 5 years of oral service.

  1. In-situ processing of aluminum nitride particle reinforced aluminum alloy composites

    Science.gov (United States)

    Zheng, Qingjun

    Discontinuously reinforced aluminum alloy composites (DRACs) have potential applications in automotive, electronic packaging, and recreation industries. Conventional processing of DRACs is by incorporation of ceramic particles/whiskers/fibers into matrix alloys. Because of the high cost of ceramic particles, DRACs are expensive. The goal of this work was to develop a low-cost route of AlN-Al DRACs processing through bubbling and reacting nitrogen and ammonia gases with aluminum alloy melt in the temperature range of 1373--1523 K. Thermodynamic analysis of AlN-Al alloy system was performed based on Gibbs energy minimization theory. AlN is stable in aluminum, Al-Mg, Al-Si, Al-Zn, and Al-Li alloys over the whole temperature range for application and processing of DRACs. Experiments were carried out to form AlN by bubbling nitrogen and ammonia gases through aluminum, Al-Mg, and Al-Si alloy melts. Products were characterized with XRD, SEM, and EDX. The results showed that in-situ processing of AlN reinforced DRACs is technically feasible. Significant AlN was synthesized by bubbling deoxidized nitrogen and ammonia gases. When nitrogen gas was used as the nitrogen precursor, the AlN particles formed in-situ are small in size, (interface. In comparison with nitrogen gas, bubbling ammonia led to formation of AlN particles in smaller size (about 2 mum or less) at a significantly higher rate. Ammonia is not stable and dissociated into nitrogen and hydrogen at reaction temperatures. The hydrogen functions as oxygen-getter at the interface and benefits chemisorption of nitrogen, thereby promoting the formation of AlN. The overall process of AlN formation was modeled using two-film model. For nitrogen bubbling gas, the whole process is controlled by chemisorption of nitrogen molecules at the gas bubble - aluminum melt interface. For ammonia precursor, the rate of the overall process is limited by the mass transfer of nitrogen atoms in the liquid boundary layer. The models agree

  2. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    TAI Feng; GUO Fu

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced compos-ite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of parti-cle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  3. Macroscopic response of particle-reinforced elastomers subjected to prescribed torques or rotations on the particles

    Science.gov (United States)

    Siboni, Morteza H.; Ponte Castañeda, Pedro

    2016-06-01

    Particle-reinforced rubbers are composite materials consisting of randomly distributed, stiff fibers/particles in a soft elastomeric material. Since the particles are stiff compared to the embedding rubber, their deformation can be ignored for all practical purposes. However, due to the softness of the rubber, they can undergo rigid body translations and rotations. Constitutive models accounting for the effect of such particle motions on the macroscopic response under prescribed deformations on the boundary have been developed recently. But, in some applications (e.g., magneto-active elastomers), the particles may experience additional torques as a consequence of an externally applied (magnetic) field, which, in turn, can affect the overall rotation of the particles in the rubber, and therefore also the macroscopic response of the composite. This paper is concerned with the development of constitutive models for particle-reinforced elastomers, which are designed to account for externally applied torques on the internally distributed particles, in addition to the externally applied deformation on the boundary of the composite. For this purpose, we propose a new variational framework involving suitably prescribed eigenstresses on the particles. For simplicity, the framework is applied to an elastomer reinforced by aligned, rigid, cylindrical fibers of elliptical cross section, which can undergo finite rotations in the context of a finite-deformation, plane strain problem for the composite. In particular, expressions are derived for the average in-plane rotation of the fibers as a function of the torques that are applied on them, both under vanishing and prescribed strain on the boundary. The results of this work will make possible the development of improved constitutive models for magneto-active elastomers, and other types of smart composite materials that are susceptible to externally applied torques.

  4. Surface morphology and fracture in handpiece adjusting of a leucite-reinforced glass ceramic with coarse diamond burs

    International Nuclear Information System (INIS)

    Highlights: ► Morphology and fracture on the removed leucite-reinforced glass ceramic. ► Morphology consisted of microfracture, chipping, ductile scratches, smear areas. ► Brittle fracture was the primary mechanism for the ceramic removal. ► Lateral and radial cracks due to the mechanical impact of diamond burs. ► Temperature-induced phase transformations were detected in leucite-reinforced glass ceramic, which might cause crack initiation. - Abstract: The aim of this paper was to understand surface morphology and fracture occurring on leucite-reinforced glass ceramic surfaces adjusted with coarse diamond burs. The surface roughness was quantitatively assessed using stylus profilometry and was analyzed statistically. The surface morphology was viewed using scanning electron microscopy. Surface phase transformations were preliminarily studied using Raman spectrometry. The results show that the surface roughness did not significantly depend on either depth of cut (p > 0.05) or feed rate (p > 0.05). However, when decreasing the depth of cut and the feed rate, a tendency for brittle-to-ductile transition existed. The surface morphology consisted of microfracture, chipping, ductile removal scratches, smear areas and debris. Brittle fracture was the primary mechanism for material removal. Lateral and radial cracks due to the mechanical impact of diamond burs were the major cause of surface fracture in the leucite-reinforced glass ceramic. The maximum adjusting temperatures on the adjusted surfaces were estimated based on heat transfer analysis. The Raman spectra of the adjusted and unadjusted surfaces show a strong temperature-dependence of Raman shifts near 525–529 cm−1. This indicates the occurrence of temperature-induced cubic-tetragonal phase transformations in the adjusted leucite glass ceramic surfaces. These phase transformations are considered to contribute crack initiation and propagation on the adjusted surfaces.

  5. Modeling of the mechanical behavior of fiber-reinforced ceramic composites using finite element method (FEM

    Directory of Open Access Journals (Sweden)

    Dimitrijević M.M.

    2014-01-01

    Full Text Available Modeling of the mechanical behavior of fiber-reinforced ceramic matrix composites (CMC is presented by the example of Al2O3 fibers in an alumina based matrix. The starting point of the modeling is a substructure (elementary cell which includes on a micromechanical scale the statistical properties of the fiber, matrix and fiber-matrix interface and their interactions. The numerical evaluation of the model is accomplished by means of the finite element method. The numerical results of calculating the elastic modulus of the composite dependance on the quantity of the fibers added and porosity was compared to experimental values of specimens having the same composition. [Projekat Ministarstva nauke Republike Srbije, br. ON174004 i TVH to project III45012

  6. Porosity characterization of fiber-reinforced ceramic matrix composite using synchrotron X-ray computed tomography

    International Nuclear Information System (INIS)

    The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a 'node-bond' geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9% for the composite, amid which there is about 7.1∼ 9.3% closed micropores

  7. Thermal stability of segmented polyurethane elastomers reinforced by clay particles

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2009-01-01

    Full Text Available The aim of this work was to determine the influence of clay nanoparticles on thermal properties of segmented polyurethanes based on hexamethylene- diisocyanate, aliphatic polycarbonate diol and 1,4-butanediol as chain extender. The organically modified particles of montmorillonite and bentonite were used as reinforcing fillers. The structure of elastomeric materials was varied either by diol type or chain extender content. The ratio of OH groups from diol and chain extender (R was either 1 or 10. Thermal properties of prepared materials were determined using modulated differential scanning calorimetry (MDSC. Thermal stability of obtained elastomers has been studied by simultaneously thermogravimetry coupled with DSC. The glass transition temperature, Tg, of soft segments for all investigated samples was about -33°C. On the basis of DTG results, it was concluded that obtained materials were very stable up to 300°C.

  8. Fiber reinforced superalloys, ceramics, and refractory metals, and directionally solidified eutectics (heat-resistant composites)

    International Nuclear Information System (INIS)

    High-temperature composites have been shown to have excellent elevated-temperature tensile and stress-rupture strengths and specific strengths. Tungsten alloy fiber reinforced superalloys have been demonstrated to have stress rupture strengths at 20000F superior to superalloys and sufficient impact resistance for gas turbines. Recently developed tungsten alloy fibers should permit production of composites with use-temperatures (gas turbine blades, vanes) as high as 24000F. Their main problem is associated with the direction and perfection of growth of strong whiskers or lamina in irregularly shaped components. Artificially made whisker composites are believed to warrant serious consideration. Use-temperatures of refractory metal matrix composites can be as much as 25000F for Nb matrix composites and over 30000F for W matrix composites. Ceramic matrix composites with use-temperatures ranging from 18000F to over 30000F are possibilities. Stationary, large, turbines for power generation may make use of refractory fiber/superalloy matrix, ceramic matrix, and coated refractory matrix composites. Such an application may capitalize on the high-temperature strength and high use-temperatures of the composites, which, in turn, will enhance engine performance. (127 references, 62 fig, 22 tables) (U.S.)

  9. Mode I Fracture Toughness Prediction for Multiwalled-Carbon-Nanotube Reinforced Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Henager, Charles H.

    2015-08-27

    This article develops a multiscale model to predict fracture toughness of multiwalled-carbon-nanotube (MWCNT) reinforced ceramics. The model bridges different scales from the scale of a MWCNT to that of a composite domain containing a macroscopic crack. From the nano, micro to meso scales, Eshelby-Mori-Tanaka models combined with a continuum damage mechanics approach are explored to predict the elastic damage behavior of the composite as a function of MWCNT volume fraction. MWCNTs are assumed to be randomly dispersed in a ceramic matrix subject to cracking under loading. A damage variable is used to describe matrix cracking that causes reduction of the elastic modulus of the matrix. This damage model is introduced in a modified boundary layer modeling approach to capture damage initiation and development at a tip of a pre-existing crack. Damage and fracture are captured only in a process window containing the crack tip under plane strain Mode I loading. The model is validated against the published experimental fracture toughness data for a MWCNT 3 mol% yttria stabilized zirconia composite system. In addition, crack resistance curves as a function of MWCNT content are predicted and fitted by a power law as observed in the experiments on zirconia.

  10. Amorphization of complex ceramics by heavy-particle irradiations

    International Nuclear Information System (INIS)

    Complex ceramics, for the purpose of this paper, include materials that are generally strongly bonded (mixed ionic and covalent), refractory and frequently good insulators. They are distinguished from simple, compact ceramics (e.g., MgO and UO2) by structural features which include: (1) open network structures, best characterized by a consideration of the shape, size and connectivity of coordination polyhedra; (2) complex compositions which characteristically lead to multiple cation sites and lower symmetry; (3) directional bonding; (4) bond-type variations within the structure. The heavy particle irradiations include ion-beam irradiations and recoil-nucleus damage resulting from a-decay events from constituent actinides. The latter effects are responsible for the radiation-induced transformation to the metamict state in minerals. The responses of these materials to irradiation are complex, as energy may be dissipated ballistically by transfer of kinetic energy from an incident projectile or radiolytically by conversion of radiation-induced electronic excitations into atomic motion. This results in isolated Frenkel defect pairs, defect aggregates, isolated collision cascades or bulk amorphization. Thus, the amorphization process is heterogeneous. Only recently have there been systematic studies of heavy particle irradiations of complex ceramics on a wide variety of structure-types and compositions as a function of dose and temperature. In this paper, we review the conditions for amorphization for the tetragonal orthosilicate, zircon [ZrSiO4]; the hexagonal orthosilicate/phosphate apatite structure-type [X10(ZO4)6(F,Cl,O)2]; the isometric pyrochlores [A1-2B2O6(O,OH,F)0-1pH2O] and its monoclinic derivative zirconotite [CaZrTi2O7]; the olivine (derivative - hcp) structure types, α-VIA2IVBO4, and spinel (ccp), γ-VIA2IVBO4

  11. Properties and performance of polysiloxane-derived ceramic matrix in heat resistant composites reinforced with R-glass or fine ceramic fibres

    Czech Academy of Sciences Publication Activity Database

    Černý, Martin; Glogar, Petr; Sucharda, Zbyněk; Machovič, V.

    2005-01-01

    Roč. 49, č. 3 (2005), s. 145-152. ISSN 0862-5468 R&D Projects: GA ČR(CZ) GA106/02/0177; GA ČR(CZ) GP106/02/P025 Institutional research plan: CEZ:AV0Z30460519 Keywords : polysiloxane resin * fibre-reinforced composite * mechanical properties Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass Impact factor: 0.463, year: 2005

  12. Tensile and Compressive Responses of Ceramic and Metallic Nanoparticle Reinforced Mg Composites

    Directory of Open Access Journals (Sweden)

    Quy Bau Nguyen

    2013-05-01

    Full Text Available In the present study, room temperature mechanical properties of pure magnesium, Mg/ZrO2 and Mg/(ZrO2 + Cu composites with various compositions are investigated. Results revealed that the use of hybrid (ZrO2 + Cu reinforcements in Mg led to enhanced mechanical properties when compared to that of single reinforcement (ZrO2. Marginal reduction in mechanical properties of Mg/ZrO2 composites were observed mainly due to clustering of ZrO2 particles in Mg matrix and lack of matrix grain refinement. Addition of hybrid reinforcements led to grain size reduction and uniform distribution of hybrid reinforcements, globally and locally, in the hybrid composites. Macro- and micro- hardness, tensile strengths and compressive strengths were all significantly increased in the hybrid composites. With respect to unreinforced magnesium, failure strain was almost unchanged under tensile loading while it was reduced under compressive loading for both Mg/ZrO2 and Mg/(ZrO2 + Cu composites.

  13. The influence of reinforcing particles on mechanical and tribological properties and microstructure of the steel-TiB2 composites

    Directory of Open Access Journals (Sweden)

    I. Sulima

    2011-09-01

    Full Text Available Purpose: The present work aims to investigate the effect of the reinforcing ceramic particles on the mechanical and tribological properties and microstructure of the steel-TiB2 composites.Design/methodology/approach: The austenitic AISI316L stainless steel reinforced with 10 vol.% and 20 vol.% TiB2 particles was produced using the high temperature-high pressure (HT-HP method. The sintering process was carried out at pressure of 7.0±0.2 GPa and temperature of 1200°C for 60 seconds. Density of sintered materials was measured according to the Archimedes principle. Mechanical properties were determined by Vickers hardness and compression test. The friction coefficient was measured using ball-on-disk method. This tests were realized at room temperature. Microstructural observations were carried out using scanning electron microscopy.Findings: The materials were characterized by very high level of consolidation, which was equal to 96% for composites with 10 vol.% and 20 vol.% TiB2 particles. The results show that the composites exhibited higher Young’s modulus, Vickers hardness and compression strength when compared with conventionally austenitic AISI316L stainless steel. The addition of 20 vol.% of TiB2 particles to steel caused significant reduction of the values of friction coefficient. The SEM studies of composites allowed to reveal TiB2 phase along grain boundaries. In case of the composite with 20 vol.% TiB2, the continuous layer of ceramic along the grain boundaries was observed.Practical implications: The obtained test results may be used to optimize the sintering process of the steel-TiB2 composites by high temperature methods. These results may be used to design new materials i.e. austenitic stainless steel reinforced with TiB2 ceramic.Originality/value: The work provide essential information on the effect of the TiB2 particles on the mechanical and tribological properties of composites.

  14. Interaction mechanisms between ceramic particles and atomized metallic droplets

    Science.gov (United States)

    Wu, Yue; Lavernia, Enrique J.

    1992-10-01

    The present study was undertaken to provide insight into the dynamic interactions that occur when ceramic particles are placed in intimate contact with a metallic matrix undergoing a phase change. To that effect, Al-4 wt pct Si/SiCp composite droplets were synthesized using a spray atomization and coinjection approach, and their solidification microstructures were studied both qualitatively and quantitatively. The present results show that SiC particles (SiCp) were incor- porated into the matrix and that the extent of incorporation depends on the solidification con- dition of the droplets at the moment of SiC particle injection. Two factors were found to affect the distribution and volume fraction of SiC particles in droplets: the penetration of particles into droplets and the entrapment and/or rejection of particles by the solidification front. First, during coinjection, particles collide with the atomized droplets with three possible results: they may penetrate the droplets, adhere to the droplet surface, or bounce back after impact. The extent of penetration of SiC particles into droplets was noted to depend on the kinetic energy of the particles and the magnitude of the surface energy change in the droplets that occurs upon impact. In liquid droplets, the extent of penetration of SiC particles was shown to depend on the changes in surface energy, ΔEs, experienced by the droplets. Accordingly, large SiC particles encoun- tered more resistance to penetration relative to small ones. In solid droplets, the penetration of SiC particles was correlated with the dynamic pressure exerted by the SiC particles on the droplets during impact and the depth of the ensuing crater. The results showed that no pene- tration was possible in such droplets. Second, once SiC particles have penetrated droplets, their final location in the microstructure is governed by their interactions with the solidification front. As a result of these interactions, both entrapment and rejection of

  15. Effect of reinforcement particle size on the tribological properties of nano-diamond filled polytetrafluoroethylene based coating.

    Science.gov (United States)

    Lim, D P; Lee, J Y; Lim, D S; Ahn, S G; Lyo, I W

    2009-07-01

    The tribological properties of PTFE composite coatings reinforced by nano-diamonds were investigated. Mechanical particle size reduction and dispersion of nano-diamond aggregates were performed by milling with ceramic beads in an organic solvent. Particle size was controlled by the milling time. Pastes comprising a PTFE solution mixed with nano-diamond having various sizes were coated on the aluminum substrate. Ball-on-plate type wear test was performed to investigate the friction and wear behavior. The results indicated that the addition of nano-diamonds effectively improved tribological performance of the PTFE coating. The reduction in nano-diamond sizes were not always improved the wear resistance of PTFE coating. This unexpected behavior was explained by observation on the worn surfaces and wear debris. PMID:19916429

  16. Flexural creep of coated SiC-fiber-reinforced glass-ceramic composites

    International Nuclear Information System (INIS)

    This study reports the flexural creep behavior of a fiber-reinforced glass-ceramic and associated changes in microstructure. SiC fibers were coated with a dual layer of SiC/BN to provide a weak interface that was stable at high temperatures. Flexural creep, creep-rupture, and creep-strain recovery experiments were conducted on composite material and barium-magnesium aluminosilicate matrix from 1,000 to 1,200 C. Below 1,130 C, creep rates were extremely low (∼10-9 s-1), preventing accurate measurement of the stress dependence. Above 1,130 C, creep rates were in the 10-8 s-1 range. The creep-rupture strength of the composite at 1,100 C was about 75--80% of the fast fracture strength. Creep-strain recovery experiments showed recovery of up to 90% under prolonged unloading. Experimental creep results from the composite and the matrix were compared, and microstructural observations by TEM were employed to assess the effectiveness of the fiber coatings and to determine the mechanism(s) of creep deformation and damage

  17. Residual stress analysis in carbon fiber-reinforced SiC ceramics

    International Nuclear Information System (INIS)

    Systematic residual stress analyses are reported, carried out in long-fiber reinforced SiC ceramics. The laminated Cfiber/SiCmatrix specimens used were prepared by polymer pyrolysis, and the structural component specimens used are industrial products. Various diffraction methods have been applied for non-destructive evaluation of residual stress fields, so as to completely detect the residual stresses and their distribution in the specimens. The residual stress fields at the surface (μm) have been measured using characteristic X-radiation and applying the sin 2ψ method as well as the scatter vector method. For residual stress field analysis in the mass volume (cm), neutron diffraction has been applied. The stress fields in the fiber layers (approx. 250μm) have been measured as a function of their location within the laminated composite by using an energy-dispersive method and synchrotron radiation. By means of the systematic, process-accompanying residual stress and phase analyses, conclusions can be drawn as to possible approaches for optimization of fabrication parameters. (orig./CB)

  18. Modeling the Tensile Strength of Carbon Fiber - Reinforced Ceramic - Matrix Composites Under Multiple Fatigue Loading

    Science.gov (United States)

    Li, Longbiao

    2016-06-01

    An analytical method has been developed to investigate the effect of interface wear on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs) under multiple fatigue loading. The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure and the difference existed in the new and original interface debonded region. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress degradation model and fibers strength degradation model have been adopted to analyze the interface wear effect on the tensile strength of the composite subjected to multiple fatigue loading. Under tensile loading, the fibers failure probabilities were determined by combining the interface wear model and fibers failure model based on the assumption that the fiber strength is subjected to two - parameter Weibull distribution and the loads carried by broken and intact fibers satisfy the Global Load Sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength corresponding to multiple fatigue peak stress levels and different cycle number have been analyzed.

  19. Fabrication of Al-based composites reinforced with Al2O3-Tib2 ceramic composite particulates using vortex-casting method

    Directory of Open Access Journals (Sweden)

    Roshan M.R.

    2013-01-01

    Full Text Available Vortex casting is one of the simplest methods of producing metal matrix composites (MMCs. However, this simple method does have some drawbacks, which reduce the mechanical properties of the produced composites. In this study, we tried to modify the process of composite production before, during, and after the casting procedure. Low-cost Al2O3-TiB2 ceramic composite particles, which produced after combustion synthesis, were used as reinforcement. These powders, which are thermodynamically stable with molten aluminum below 900°C, were mixed with aluminum and magnesium powders before casting using ball milling and the mixed powders were injected into the molten metal (pure Al. This process was applied to enhance the wettability of ceramic particles with molten aluminum. After casting, warm equal channel angular pressing (ECAP and hot extrusion processes were applied to investigate their effects on the mechanical properties of the final composites. It was revealed that both warm ECAP and hot extrusion have a strong influence on increasing the mechanical properties mainly due to decreasing the amount of porosities.

  20. Production and wear properties of metal matrix composites reinforced with boride particles

    International Nuclear Information System (INIS)

    Highlights: • Production of MMC reinforced with in situ boride particles have been investigated. • Higher reinforcement percentage of borides was produced by a filtration technique. • Hardness of boride particles was measured as approximately 3050 Hv. • The cumulative weight loss of the composite was lower than of the matrix alone. - Abstract: Production and properties of metal matrix composites reinforced with in situ cuboidal boride particles have been investigated. Boron 3 weight (wt.)% was dissolved in an aluminium copper alloy at 1400 °C through direct addition of boron oxide (B2O3) which resulted in 6.14 volume (vol.)% reinforcing phase of cuboidal boride particles in the alloy. Higher reinforcement volume per cent of in situ boride particles in the Al–Cu matrix has been produced by using a filtration device. Metallographic examinations, optical microscopy, and a wet chemistry analysis technique for determination of boron content have been used to reveal the structure and the volume fraction of the reinforcement phase. The wear behaviour of the composite and matrix were investigated using a pin-on-disk tester under different conditions. Results showed that average cumulative weight loss of the new composite can be decreased by 68% with addition of 33 vol.% of cuboidal boride particles into the Al–Cu matrix

  1. Mechanical behavior of silicon carbide fiber-reinforced strontium aluminosilicate glass-ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, N.P. [National Aeronautics and Space Administration, Cleveland, OH (United States). Lewis Research Center

    1997-07-15

    Unidirectional CVD SiC fiber-reinforced SrO.Al{sub 2}O{sub 3}.2SiO{sub 2} (SAS) glass-ceramic matrix composites have been fabricated by hot pressing. Both carbon-rich surface coated SCS-6 and uncoated SCS-0 fibers were used as reinforcements. Monoclinic celsian, SrAl{sub 2}Si{sub 2}O{sub 8}, was the only crystalline phase observed in the matrix from X-ray diffraction. During three point flexure testing of composites, a test span to thickness ratio of {>=}25 was necessary to avoid delamination. Strong and tough SCS-6/SAS composites having a first matrix cracking stress of {proportional_to}300 MPa and an ultimate strength of {proportional_to}825 MPa were fabricated. No chemical reaction between the SCS-6 fibers and the matrix was observed after high temperature processing. The SCS-0/SAS composite, having a fiber volume fraction of 0.24, exhibited a first matrix cracking stress of {proportional_to}231{+-}20 MPa and ultimate strength of 265{+-}17 MPa indicating a somewhat limited improvement over the monolithic material. From fiber push-out tests, the fiber/matrix debonding stress ({tau}{sub debond}) and frictional sliding stress ({tau}{sub friction}) in the SCS-6/SAS system were evaluated to be {proportional_to}6.7{+-}2.3 and 4.3{+-}0.6 MPa, respectively, indicating a weak interface. However, for the SCS-0/SAS composite, somewhat higher values of {proportional_to}17.5{+-}2.7 MPa for {tau}{sub debond} and 11.3{+-}1.6 MPa for {tau}{sub friction} respectively, were observed; some of the fibers were strongly bonded to the matrix and could not be pushed out. Examination of fracture surfaces revealed limited short pull-out lengths of SCS-0 fibers. The applicability of theoretical models in predicting the values of first matrix cracking stress and ultimate strength of these composites has been investigated. (orig.)

  2. Influence of hard ceramic particles on structure and properties of TGM

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: The Powder Metallurgy route has been chosen to fabricate tool gradient materials with high disproportion of cobalt matrix portion between core and surface layer. In the paper structure and properties of TGM have been shown.Design/methodology/approach: SEM, light microscope, microhardness tests, density examination.Findings: According to carried out researches it could be stated, that forming the gradient materials with highest amount of complex carbide (W,TiC 90-95%, using uniaxial unilateral pressing, could be possible after adding into each layer of mixes 2 % of paraffin lubricant. High diversification of cobalt matrix ratio in comparison to hard phases in subsequent layers of gradient materials leads to their deformation in as sintered state. In case of all gradient materials, mean hardness was equal about 1600 HV1. Whereas, hardness of lower cobalt matrix rich layers brought values about 1450 HV1 and increased up to 1800 HV1 for lower layer of material rich with hard carbide phases.Practical implications: Material presented in this paper is characterized by very high hardness of the surface and relative ductility of core. TGM is a smoothly varying distribution of phases element composition.Originality/value: In the paper the manufacturing of TGM on basis of different portion of cobalt reinforced with hard ceramics particles carried out in order to improve the abrasion resistance and ductility of tool cutting materials.

  3. Ti particle-reinforced surface layers in Al: Effect of particle size on microstructure, hardness and wear

    Energy Technology Data Exchange (ETDEWEB)

    Mordyuk, B.N., E-mail: mordyuk@imp.kiev.ua [Kurdyumov Institute for Metal Physics, 36 Academician Vernadsky Boulevard, UA-03680, Kyiv (Ukraine); Silberschmidt, V.V. [Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, LE11 3TU (United Kingdom); Prokopenko, G.I. [Kurdyumov Institute for Metal Physics, 36 Academician Vernadsky Boulevard, UA-03680, Kyiv (Ukraine); Nesterenko, Yu.V. [National Technical University ' Kyiv Polytechnic Institute' , 37 Peremohy Avenue, UA-03056, Kyiv (Ukraine); Iefimov, M.O. [Frantzevich Institute for Problems of Materials Science, 3 Krzhyzhanivsky Street, UA-03142, Kyiv (Ukraine)

    2010-11-15

    Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 {mu}m and milled (0.3-0.5 {mu}m). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200-400 nm, while reinforcement with larger particles results in relatively large Al grains (1-2 {mu}m). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti{sub 3}Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles.

  4. Ti particle-reinforced surface layers in Al: Effect of particle size on microstructure, hardness and wear

    International Nuclear Information System (INIS)

    Two types of Ti particles are used in an ultrasonic impact peening (UIP) process to modify sub-surface layers of cp aluminium atomized, with an average size of approx. 20 μm and milled (0.3-0.5 μm). They are introduced into a zone of severe plastic deformation induced by UIP. The effect of Ti particles of different sizes on microstructure, phase composition, microhardness and wear resistance of sub-surface composite layers in aluminium is studied in this paper. The formed layers of a composite reinforced with smaller particles have a highly misoriented fine-grain microstructure of its matrix with a mean grain size of 200-400 nm, while reinforcement with larger particles results in relatively large Al grains (1-2 μm). XRD, SEM, EDX and TEM studies confirm significantly higher particle/matrix bonding in the former case due to formation of a Ti3Al interlayer around Ti particles with rough surface caused by milling. Different microstructures determine hardness and wear resistance of reinforced aluminium layers: while higher magnitudes of microhardness are observed for both composites (when compared with those of annealed and UIP-treated aluminium), the wear resistance is improved only in the case of reinforcement with small particles.

  5. Robocasting of Ceramics and Composites Using Fine Particle Suspensions

    International Nuclear Information System (INIS)

    Solid freeform fabrication is the near-net-shape manufacturing of components by sequentially stacking thin layers of material until complicated three dimensional shapes are produced. The operation is computer controlled and requires no molds. This exciting new field of technology provides engineers with the ability to rapidly produce prototype parts directly from CAD drawings and oftentimes little or no machining is necessary after fabrication. Techniques for freeform fabrication with several types of plastics and metals are already quite advanced and maybe reviewed in references 1 and 2. Very complicated plastic models can be fabricated by stereolithography, selective laser sintering, fused deposition modeling, or three-dimensional ink jet printing. Metals may be freeformed by the LENS(trademark) technique and porous ceramic bodies by three dimensional printing into a porous powder bed. However, methods for freeform fabrication that utilize particulate slurries to build dense ceramics and composites are not as well developed. The techniques that are being developed for the freeform fabrication of dense structural ceramics primarily revolve around the sequential layering of ceramic loaded polymers or waxes. Laminated Object Manufacturing and CAM-LEM processing use controlled stacking and laser cutting of ceramic tapes[2,3]. Similar to fused deposition modeling, ceramic loaded polymer/wax filaments are being used for the fused deposition of ceramics[2,4]. Extrusion freeform fabrication uses high pressure extrusion to deposit layers of ceramic loaded polymer/wax systems[1]. Modified stereolithographic techniques are also being developed using ceramic loaded ultraviolet curable resins[2]. Pre-sintered parts made with any of these techniques typically have 40-55 vol.% polymeric binder. In this regard, these techniques are analogous to powder injection molding of ceramics. Very long and complicated burnout heat treatments are necessary to produce a dense ceramic, free

  6. Robocasting of Ceramics and Composites Using Fine Particle Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    CESARANO III,JOSEPH

    1999-10-28

    Solid freeform fabrication is the near-net-shape manufacturing of components by sequentially stacking thin layers of material until complicated three dimensional shapes are produced. The operation is computer controlled and requires no molds. This exciting new field of technology provides engineers with the ability to rapidly produce prototype parts directly from CAD drawings and oftentimes little or no machining is necessary after fabrication. Techniques for freeform fabrication with several types of plastics and metals are already quite advanced and maybe reviewed in references 1 and 2. Very complicated plastic models can be fabricated by stereolithography, selective laser sintering, fused deposition modeling, or three-dimensional ink jet printing. Metals may be freeformed by the LENS{trademark} technique and porous ceramic bodies by three dimensional printing into a porous powder bed. However, methods for freeform fabrication that utilize particulate slurries to build dense ceramics and composites are not as well developed. The techniques that are being developed for the freeform fabrication of dense structural ceramics primarily revolve around the sequential layering of ceramic loaded polymers or waxes. Laminated Object Manufacturing and CAM-LEM processing use controlled stacking and laser cutting of ceramic tapes [2,3]. Similar to fused deposition modeling, ceramic loaded polymer/wax filaments are being used for the fused deposition of ceramics [2,4]. Extrusion freeform fabrication uses high pressure extrusion to deposit layers of ceramic loaded polymer/wax systems[1]. Modified stereolithographic techniques are also being developed using ceramic loaded ultraviolet curable resins [2]. Pre-sintered parts made with any of these techniques typically have 40-55 vol.% polymeric binder. In this regard, these techniques are analogous to powder injection molding of ceramics. Very long and complicated burnout heat treatments are necessary to produce a dense ceramic

  7. Effects of Particle Size on the Shear Behavior of Coarse Grained Soils Reinforced with Geogrid

    Directory of Open Access Journals (Sweden)

    Daehyeon Kim

    2014-02-01

    Full Text Available In order to design civil structures that are supported by soils, the shear strength parameters of soils are required. Due to the large particle size of coarse-grained soils, large direct shear tests should be performed. In this study, large direct shear tests on three types of coarse grained soils (4.5 mm, 7.9 mm, and 15.9 mm were performed to evaluate the effects of particle size on the shear behavior of coarse grained soils with/without geogrid reinforcements. Based on the direct shear test results, it was found that, in the case of no-reinforcement, the larger the maximum particle size became, the larger the friction angle was. Compared with the no-reinforcement case, the cases reinforced with either soft geogrid or stiff geogrid have smaller friction angles. The cohesion of the soil reinforced with stiff geogrid was larger than that of the soil reinforced with soft geogrid. The difference in the shear strength occurs because the case with a stiff geogrid has more soil to geogrid contact area, leading to the reduction in interlocking between soil particles.

  8. Selected properties of the aluminium alloy base composites reinforced with intermetallic particles

    OpenAIRE

    M. Adamiak

    2005-01-01

    Purpose: The main aim of this work is to investigate two types of intermetallics TiAl and Ti3Al as reinforcement and their influence on selected properties and microstructure of aluminium matrix composites.Design/methodology/approach: Aluminium matrix composites were produced employing the atomised aluminium alloy AA6061 as metal matrix, when as reinforcement TiAl and Ti3Al intermetallics particles were used. The powders were cold pressed and then hot extruded. To evaluate the effect of mecha...

  9. High-temperature mechanical properties of aluminium alloys reinforced with boron carbide particles

    International Nuclear Information System (INIS)

    The mechanical properties of particulate-reinforced metal-matrix composites based on aluminium alloys (6061 and 7015) at high temperatures were studied. Boron carbide particles were used as reinforcement. All composites were produced by hot extrusion. The tensile properties and fracture analysis of these materials were investigated at room temperature and at high temperature to determine their ultimate strength and strain to failure. The fracture surface was analysed by scanning electron microscopy

  10. Fiber-reinforced ceramics for thermostructural applications, produced by polymer impregnation pyrolysis

    OpenAIRE

    Mingazzini, Claudio

    2014-01-01

    Several CFCC (Continuous Fiber Composite Ceramics) production processes were tested, concluding that PIP (Polymer Impregnation, or Infiltration, Pyrolysis) and CBC (Chemically Bonded Ceramics) based procedures have interesting potential applications in the construction and transportation fields, thanks to low costs to get potentially useful thermomechanical performances. Among the different processes considered during the Doctorate (from the synthesis of new preceramic polymers, to the PIP...

  11. Effect of heat treatment on microstructure and interface of SiC particle reinforced 2124 Al matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Durbadal, E-mail: durbadal73@yahoo.co.in [MEF Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Viswanathan, Srinath [Dept of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL (United States)

    2013-11-15

    The microstructure and interface between metal matrix and ceramic reinforcement of a composite play an important role in improving its properties. In the present investigation, the interface and intermetallic compound present in the samples were characterized to understand structural stability at an elevated temperature. Aluminum based 2124 alloy with 10 wt.% silicon carbide (SiC) particle reinforced composite was prepared through vortex method and the solid ingot was deformed by hot rolling for better particle distribution. Heat treatment of the composite was carried out at 575 °C with varying holding time from 1 to 48 h followed by water quenching. In this study, the microstructure and interface of the SiC particle reinforced Al based composites have been studied using optical microscopy, scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), electron probe micro-analyzer (EPMA) associated with wavelength dispersive spectroscopy (WDS) and transmission electron microscopy (TEM) to identify the precipitate and intermetallic phases that are formed during heat treatment. The SiC particles are uniformly distributed in the aluminum matrix. The microstructure analyses of Al–SiC composite after heat treatment reveal that a wide range of dispersed phases are formed at grain boundary and surrounding the SiC particles. The energy dispersive X-ray spectroscopy and wavelength dispersive spectroscopy analyses confirm that finely dispersed phases are CuAl{sub 2} and CuMgAl{sub 2} intermetallic and large spherical phases are Fe{sub 2}SiAl{sub 8} or Al{sub 15}(Fe,Mn){sub 3}Si. It is also observed that a continuous layer enriched with Cu and Mg of thickness 50–80 nm is formed at the interface in between Al and SiC particles. EDS analysis also confirms that Cu and Mg are segregated at the interface of the composite while no carbide is identified at the interface. - Highlights: • The composite was successfully heat treated at 575°C for 1

  12. Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

    Science.gov (United States)

    Sancakli, Hande Sar; Sancakli, Erkan; Eren, Meltem Mert; Ozel, Sevda; Yucel, Taner; Yildiz, Esra

    2014-01-01

    PURPOSE The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm × 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 µm silica oxide particles (Cojet™ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at α=.05. RESULTS Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used. PMID:25551002

  13. Thermal residual stresses in SiC particle reinforced aluminium composites: a study by the Taylor-based nonlocal theory of plasticity

    International Nuclear Information System (INIS)

    Strain gradient theories have been considered to be an effective means for capturing the size effects on ceramic particle-reinforced metal-matrix composites (MMCp), but the results predicted by them are significantly lower than the corresponding experimental data. One reason might be, that the thermal residual stresses caused by thermal contraction mismatch between the metal matrix and the ceramic particle were neglected in the numerical models. By incorporating the Taylor-based nonlocal theory (TNT) of plasticity, the finite element method (FEM) is applied in the present research, to investigate the effect of thermal residual stresses on the yield stress and average axial stresses of the aluminium matrix reinforced by silicon carbide particles (SiCp/Al). The elements of the matrix have been implemented in the ABAQUS finite element code through its USER-ELEMENT (UEL) interface for TNT plasticity. Some comparisons with the associated literature demonstrate that the numerical model with the thermal residual stresses is more in agreement with the experimental results.

  14. Thermodynamic analysis of chemical compatibility of ceramic reinforcement materials with niobium aluminides

    Science.gov (United States)

    Misra, Ajay K.

    1990-01-01

    Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

  15. Dynamic Effects in Elastothermodynamic Damping of Hollow Particle Reinforced Metal-Matrix Composites

    Science.gov (United States)

    Srivastava, Sunil Kumar; Mishra, Bhanu Kumar

    2016-06-01

    The Metal-Matrix Composites (MMCs) containing hollow spherical reinforcements are under active development for the applications such as space structures, submarine hulls etc. where weight is of critical importance. When these materials are subjected to a time varying strain field, energy is dissipated because of the thermoelastic effect (Elastothermodynamic Damping or ETD). The quasi-static ETD analysis for the MMCs containing hollow spherical particles has been reported in literature. The entropic approach, which is better suited for composite materials with perfect or imperfect interfaces, is used for the analysis. In the present work, the effect of inertia forces is carried out on ETD of hollow particle-reinforced MMCs. For given particle volume fractions (V p ), the inertia forces are found to be more significant at higher value of thermal parameter (Ω T1) (alternatively, frequency of vibration if reinforcement radius is fixed), large cavity volume fraction (V h ) and low value of the parameter B1.

  16. SiC nanowires reinforced MAS joint of SiC coated carbon/carbon composites to LAS glass ceramics

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic cross-section images of the samples with SiC nanowires and assembly sequence for the raw materials through the process of the hot-pressing method. Highlights: ► The SiC nanowires were firstly used as porous layer in the middle of the joint. ► The shear strength of the joint with SiC nanowires was largely improved. ► A new mode of fracture was proposed. - Abstract: In order to improve the shear strength of the joints of carbon/carbon (C/C) composites to lithium aluminum silicate (LAS) glass ceramics, SiC coating and magnesium aluminum silicate (MAS) glass ceramics were used as transition layer and middle layer, respectively, and high quality SiC nanowires were applied as the reinforcement materials in MAS. The SiC nanowires reinforced MAS joint of SiC coated C/C composites to LAS glass ceramics was prepared by a three-step technique of pack cementation, CVD and hot-pressing. The microstructures of the as-prepared joints were characterized by SEM and EDS, and the shear strength of the joints was also examined. The shear strength of the SiC–MAS joint increased from 24.0 ± 2.0 MPa to 35.5 ± 5.5 MPa after adding SiC nanowires in MAS. The load decreases in step-style but not perpendicularly after the maximum value, which demonstrates good toughness of the joint with SiC nanowire porous layer.

  17. Selected properties of the aluminium alloy base composites reinforced with intermetallic particles

    Directory of Open Access Journals (Sweden)

    M. Adamiak

    2005-12-01

    Full Text Available Purpose: The main aim of this work is to investigate two types of intermetallics TiAl and Ti3Al as reinforcement and their influence on selected properties and microstructure of aluminium matrix composites.Design/methodology/approach: Aluminium matrix composites were produced employing the atomised aluminium alloy AA6061 as metal matrix, when as reinforcement TiAl and Ti3Al intermetallics particles were used. The powders were cold pressed and then hot extruded. To evaluate the effect of mechanical milling two types of ball mills were used: a low energy (horizontal ball mill and a high energy one (eccentric ball mill. Reinforcement contents for both processes 5, 10, 15 % by weight. To determine hardness Vickers tests were performed. Microstructure observations were made by optical microscopy and scanning electron microscopy SEM.Findings: Based on the examinations carried out one can state that the mechanical milling can produce composites powders with homogenous distribution of reinforcement particles. The mechanically milled and extruded composites show finer and better distribution of reinforcement particles what leads to better mechanical properties of obtained products.Research limitations/implications: In order to evaluate with more detail the possibility of applying these composite materials at practical application, further investigations should be concentrated on the interface reaction of the matrix and reinforcing particles during elevated temperature exposition and their influence on mechanical properties.Practical implications: The composites materials produced by this way have shown significant improvement of the mechanical properties in comparision with matrix materials. Good properties of the composites make them suitable for various technical and industrial applications.Originality/value: It should be stressed that the materials as intermetallic compounds with outstanding mechanical properties and good thermal stability were

  18. Mechanical and thermal properties of sodium silicate treated moso bamboo particles reinforced PVC composites

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The main objective of this research was to study the potential of sodium silicate modification on moso bamboo particles as reinforcements for thermoplastic. Moso bamboo particles were modified with sodium silicate aqueous solutions (of 0.5%, 1%, 2%, 5% and 10% concentrations). The mechanical properties of sodium silicate treated moso bamboo particles reinforced PVC composites (BPPC) were calculated and compared with raw bamboo particles filled samples. The thermal characteristics of the BPPC were studied to investigate the feasibility of sodium silicate treatment on moso bamboo particles. The particle morphology and BPPC microstructure were investigated by scanning electron microscopy. Results showed that the tensile strength and modulus of elasticity of the BPPC increased before the concentration of sodium silicate solution reached 5% and got their maximum values of 15.72 MPa and 2956.80 MPa, respectively at 5% concentration. The modulus of rupture obtained the maximum value of 27.73 MPa at 2% concentration. The mechanical curve decreased as the concentration of solution went higher. Differential scanning calorimetric analysis illustrated that the sodium silicate solution treated BPPC possesses a better compatibility. More uniform dispersion of moso bamboo particles in PVC matrix was obtained after the sodium silicate treatment. Hence, the sodium silicate was a feasible and competitive agent of creating moso bamboo particles reinforced PVC composites.

  19. ON THE EFFECT OF NANO-PARTICLE CLUSTERING ON TOUGHENING OF NANO-COMPOSITE CERAMICS

    Institute of Scientific and Technical Information of China (English)

    董照旭; 方岱宁; 苏爱嘉

    2002-01-01

    In this paper, two and three-dimensional clustering models are developed to characterize the effect of nano-particle clustering on toughening of nanocomposite ceramics. It is found that crack pinning toughens the nano-composite ceramics because a higher stress intensity factor is needed for crack to propagate around or to pull-out the nano-particle. The nano-particle along the grain boundary steers the crack into the matrix grain due to the strong cohesion between the nanoparticle and the matrix. Since the fracture resistance of the grain boundary is lower than that of the grain lattice, the higher the probability of transgranular fracture induced by nano-particles, the tougher is the nano-composite. However, both crack pinning and transgranular fracture are affected by nano-particle clustering. Nanoparticle clustering, which increases with increasing volume fraction of nano-particles,leads to reduction of both the strength and toughness of the nano-composite ceramics. The larger the size of the clustered particle, and the more defects it contains, the easier it is for the crack to pass through the clustered particle, which means that the nano-particle clustering can reduce toughening induced by crack pinning and transgranular fracture. The theoretical prediction, based on the combination of the three mechanisms of nano-particles, is in agreement with the experimental data.

  20. Effect of re-melting on particle distribution and interface formation in SiC reinforced 2124Al matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Durbadal, E-mail: durbadal73@yahoo.co.in [MEF Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Viswanathan, Srinath [Dept of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL (United States)

    2013-12-15

    The interface between metal matrix and ceramic reinforcement particles plays an important role in improving properties of the metal matrix composites. Hence, it is important to find out the interface structure of composite after re-melting. In the present investigation, the 2124Al matrix with 10 wt.% SiC particle reinforced composite was re-melted at 800 °C and 900 °C for 10 min followed by pouring into a permanent mould. The microstructures reveal that the SiC particles are distributed throughout the Al-matrix. The volume fraction of SiC particles varies from top to bottom of the composite plate and the difference increases with the decrease of re-melting temperature. The interfacial structure of re-melted 2124Al–10 wt.%SiC composite was investigated using scanning electron microscopy, an electron probe micro-analyzer, a scanning transmission electron detector fitted with scanning electron microscopy and an X-ray energy dispersive spectrometer. It is found that a thick layer of reaction product is formed at the interface of composite after re-melting. The experimental results show that the reaction products at the interface are associated with high concentration of Cu, Mg, Si and C. At re-melting temperature, liquid Al reacts with SiC to form Al{sub 4}C{sub 3} and Al–Si eutectic phase or elemental Si at the interface. High concentration of Si at the interface indicates that SiC is dissociated during re-melting. The X-ray energy dispersive spectrometer analyses confirm that Mg- and Cu-enrich phases are formed at the interface region. The Mg is segregated at the interface region and formed MgAl{sub 2}O{sub 4} in the presence of oxygen. The several elements identified at the interface region indicate that different types of interfaces are formed in between Al matrix and SiC particles. The Al–Si eutectic phase is formed around SiC particles during re-melting which restricts the SiC dissolution. - Highlights: • Re-melted composite shows homogeneous particle

  1. Novel in situ synthesized zirconium matrix composites reinforced with ZrC particles

    International Nuclear Information System (INIS)

    In the present work, novel zirconium (Zr) matrix composites reinforced by ZrC particles were prepared though the synthesis reaction from Zr and C with non-consumable vacuum arc melting. Microstructural observation indicates that the ZrC reinforcement grows in dendritic and near equiaxed shapes. The solute atom aluminum (Al) was added into the in situ ZrC/Zr composites and the ZrC reinforcement was refined. The results of room temperature compressive test show that the composites exhibit significant increase of Young's modulus and higher ultimate compressive strength (UCS) than the Zr sample, which can be attributed to the presence of ZrC and the solute atom Al in the Zr matrix. It is implied from the fractography that modification of the shape and interface of the in situ ZrC particles improve the mechanical properties of the Zr matrix composites.

  2. Encapsulation of sacrificial silicon containing particles for SH oxide ceramics via a boehmite precursor route

    OpenAIRE

    Carabat, A.L.; Zwaag, S. van der; Sloof, W.G.

    2013-01-01

    Easy crack propagation in oxide ceramic coatings limits their application in high temperature environment (e.g. such as engines and gas turbine components) [1]. In order to overcome this problem, incorporation of sacrificial particles into an oxide ceramic coating may be a viable option. Particles of silicon compounds, such as: Si3N4, SiC, MoSi2, TaSi2 and WSi2 are attractive due to their unique features of producing a reaction product (i.e. SiO2) which fills the crack and bonds well to the s...

  3. Influence of protein hydrolysis on the mechanical properties of natural rubber composites reinforced with soy protein particles

    Science.gov (United States)

    For natural rubber applications, the reinforcing fillers are used to improve the mechanical properties of the rubber. Soy protein particles have been shown to reinforce natural rubber. The hydrolysis conditions of soy protein are studied to understand its effect on the particle size and size distrib...

  4. Large Scale FEM of the effective elastic properties of particle reinforced composites

    DEFF Research Database (Denmark)

    Rauhe, Jens Christian; Pyrz, Ryszard; Lund, Erik

    2004-01-01

    Over the years several methods have been proposed for the determination of the effective elastic properties of particle reinforced composites. The material microstructures used in the present analysis is a real microstructure and a numerically generated microstructure. X-ray microtomography is us...

  5. Study on Processing Conditions of Aluminum Matrix Composites Reinforced with Boron Carbide Particles

    Institute of Scientific and Technical Information of China (English)

    Fu Xueying; Zhang Hong; Xi Huizhi; Yi Xiaosu

    2004-01-01

    Different pre-heating of boron carbide particles for reinforcement and different processing conditions were studied in this work. Being one of the most cost-effective industrial methods, conventional melt stir-casting route was utilized.Result showed that the boron carbide particles distributed well for a suitable pre-heating temperature and processed in air.No reaction product was found at the A1-B4C interfaces at the resolution limit of SEM used in that way.

  6. Microstructure and hardness of WC-Co particle reinforced iron matrix surface composite

    OpenAIRE

    Zhang Peng; Zeng Shaolian; Zhang Zhiguo

    2013-01-01

    In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS), electron probe microanalysis (EPMA), scanning electron microscope (SEM) and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle...

  7. Computational Simulation of Continuous Fiber-Reinforced Ceramic Matrix Composites Behavior

    Science.gov (United States)

    Murthy, Pappu L. N.; Chamis, Christos C.; Mital, Subodh K.

    1996-01-01

    This report describes a methodology which predicts the behavior of ceramic matrix composites and has been incorporated in the computational tool CEMCAN (CEramic Matrix Composite ANalyzer). The approach combines micromechanics with a unique fiber substructuring concept. In this new concept, the conventional unit cell (the smallest representative volume element of the composite) of the micromechanics approach is modified by substructuring it into several slices and developing the micromechanics-based equations at the slice level. The methodology also takes into account nonlinear ceramic matrix composite (CMC) behavior due to temperature and the fracture initiation and progression. Important features of the approach and its effectiveness are described by using selected examples. Comparisons of predictions and limited experimental data are also provided.

  8. Thermal fatigue mechanism of WC particles reinforced steel substrate surface composite at different thermal shock temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zulai; Jiang, Yehua; Zhou, Rong; Gao, Fan; Shan, Quan [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Tan, Jun, E-mail: tanjuncn@gmail.com [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); IFW Dresden, Institute for Complex Materials, P.O. Box 27 01 16, D-01171 Dresden (Germany); TU Dresden, Institute of Materials Science, D-01062 Dresden (Germany)

    2014-05-01

    Highlights: • WC particle reinforced steel substrate surface composites were fabricated. • The vacuum evaporative pattern casting technique was utilized. • Thermal fatigue failure of composites was governed by thermal stress and oxidation. • At 500 °C, thermal stress was the major factor to affect thermal fatigue failure. • At 800 °C, the oxidation was the most important effect to thermal fatigue failure. - Abstract: In order to provide significant references and theoretic base for the design and practical application of surface composites with high thermal fatigue performance, WC particles reinforced steel substrate surface composites were fabricated using vacuum evaporative pattern casting. And thermal fatigue behaviors of WC particles in the composites were investigated by stereomicroscope, X-ray diffraction and scanning electron microscopy. The results showed that the thermal fatigue failure of the WC particles in the composite was influenced by the combination of thermal stress and oxidation at high temperatures. When the thermal shock temperature was low (500 °C), the thermal stress was the major factor to influence the thermal fatigue failure. However, the oxidation particles played an important role with the increasing thermal shock temperature. The results might supply significant guides to the design of particles reinforced surface composites.

  9. Microstructure and hardness of WC-Co particle reinforced iron matrix surface composite

    Directory of Open Access Journals (Sweden)

    Zhang Peng

    2013-11-01

    Full Text Available In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS, electron probe microanalysis (EPMA, scanning electron microscope (SEM and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle volumetric fraction of ~38%. During solidification, interface reaction takes place between WC-Co particles and high chromium cast iron. Melting and dissolving of prefabricated particles are also found, suggesting that local Co melting and diffusion play an important role in promoting interface metallurgical bonding. The composite layer is composed of ferrite and a series of carbides, such as (Cr, W, Fe23C6, WC, W2C, M6C and M12C. The inhomogeneous hardness in the obtained composite material shows a gradient decrease from the particle reinforced metal matrix composite layer to the matrix layer. The maximum hardness of 86.3 HRA (69.5 HRC is obtained on the particle reinforced surface, strongly indicating that the composite can be used as wear resistant material.

  10. Thermal shock resistance of core reinforced all-ceramic crown systems.

    Science.gov (United States)

    Mora, G P; O'Brien, W J

    1994-02-01

    The coefficient of thermal expansion of core and veneer porcelains for all ceramic crowns must be compatible to prevent formation of stresses during the firing cycles. The purpose of this study was to use a thermal shock test to evaluate the crazing resistance of six all-ceramic crown systems. The systems tested were: Vita In-Ceram, Vita Hi-Ceram, Dicor veneered with Vitadur N, magnesia core veneered with Ceramco II, magnesia core veneered with Silhouette, and magnesia core veneered with Vita VMK 68. A maxillary central incisor was prepared with 1.0 mm axial and 1.5 mm incisal reduction. Refractory dies were prepared and crowns were fabricated using the manufacturers' recommendations. Six specimens of each system were placed inside a beaker in a furnace at 90 degrees C. After 15 min heat soak, ice water was poured into the beaker through a funnel. The samples were dried in air, reheated, and inspected for crazing using light microscopy. If crazing was observed, this would constitute a failure at a temperature difference (delta T) of 90 degrees C. If no failure occurred, the test was repeated at increasing temperature increments of 10 degrees C until failure. The crazing resistance of each system, expressed as the mean delta T, was: > 200 (Hi-Ceram), 163 +/- 14 (In-Ceram), 152 +/- 19 (Dicor/Vitadur N), 143 +/- 5 (magnesia core/Vita VMK 68), 122 +/- 21 (magnesia core/Silhouette), and 118 +/- 10 (magnesia core/Ceramco II) degrees C. All systems tested resisted crazing due to quenching in ice cold water from 100 degrees C. Systems with lower coefficients of expansion showed significantly greater resistance to thermal shock using ANOVA. PMID:8207030

  11. Investigation on Cutting Tool Performance of α-Si3N4 - β SiAlON Ceramics

    OpenAIRE

    Çalışkan, Fatih; Tatlı, Zafer; Kılıç, Serkan; Sönmez, Hakkı

    2014-01-01

    One of the ceramic products is ceramic cutting edges and these are used as cutting tools for fabrication of metal products (ferrous and non ferrous metals) at very high speeds. These cutting tools can mainly be classified silicon nitride, alumina, mixed-ceramics, titanium carbonitride, cubic boron nitride and hard ceramic particle reinforced metals. Ceramic cutting tools offer a high productivity because of their superior hardness, fracture toughness and resistance of elevated temperature whi...

  12. A New Technology of Microcrystallizing Leucite to Reinforce Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; PENG Bin; DUAN Xing-long; QIAN Fa-tang; WU Bo-lin

    2004-01-01

    The key technology and the main mechanism of microcrystallizing leucite to reirforce dentalglass ceramics were investigated. The feedstock powders were selected, mixed according to the ratios of the theoreti-cal composition of leucite, ball - milled, melted at 1600℃ and then cooled to room temperature quickly. Thecooled clinkers were ball - milled again to 4 μm. After cold - isostatic pressure molded and air sintered at 1 500℃for 1 h, the dental glass ceramics were fabricated. They have following characteristics: excellent mechanical prop-erties ( mean compressive strength is 206.6 MPa ), low sintering temperature and good reoccurrence to keep steadyquality.

  13. Experimental investigation on high temperature anisotropic compression properties of ceramic-fiber-reinforced SiO{sub 2} aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Duoqi; Sun, Yantao [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Feng, Jian [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Yang, Xiaoguang, E-mail: yxg@buaa.edu.cn [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Han, Shiwei; Mi, Chunhu [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China); Jiang, Yonggang [National Key Laboratory of Science and Technology on Advanced Ceramic Fibers and Composites, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073 (China); Qi, Hongyu [School of Energy and Power Engineering, Beihang University, P.O. Box 405, Beijing 100191 (China)

    2013-11-15

    Compression tests were conducted on a ceramic-fiber-reinforced SiO{sub 2} aerogel at high temperature. Anisotropic mechanical property was found. In-plane Young's modulus is more than 10 times higher than that of out-of-plane, but fracture strain is much lower by a factor of 100. Out-of-plane Young's modulus decreases with increasing temperature, but the in-plane modulus and fracture stress increase with temperature. The out-of-plane property does not change with loading rates. Viscous flow at high temperature is found to cause in-plane shrinkage, and both in-plane and out-of-plane properties change. Compression induced densification of aerogel matrix was also found by Scanning Electron Microscope analysis.

  14. INTERFACES IN SiC FIBER-REINFORCED GLASS-CERAMIC COMPOSITES

    OpenAIRE

    Mazerolles, L.; D. Michel; Ulmer, L.; Pastol, J.; Parlier, M.; Ritti, M.

    1990-01-01

    Interfaces between SiC Nicalon fibers and a lithium aluminum silicate (LAS) glass-ceramic matrix were investigated by transmission electron microscopy and energy-dispersive X-ray spectroscopy (EDS). Minor additive elements in the matrix, like niobium, can modify the mechanical properties of the composite because of the formation of niobium carbide at the fiber-matrix interface.

  15. Chemical Vapor Deposited SiC (SCS-0) Fiber-Reinforced Strontium Aluminosilicate Glass-Ceramic Composites

    Science.gov (United States)

    Bansal, Narottam P.

    1997-01-01

    Unidirectional SrO Al2O3 2SiO2 glass-ceramic matrix composites reinforced with uncoated Chemical Vapor Deposited (CVD) SiC (SCS-0) fibers have been fabricated by hot-pressing under appropriate conditions using the glass-ceramic approach. Almost fully dense composites having a fiber volume fraction of 0.24 have been obtained. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase observed in the matrix by x-ray diffraction. No chemical reaction was observed between the fiber and the matrix after high temperature processing. In three-point flexure, the composite exhibited a first matrix cracking stress of approx. 231 +/- 20 MPa and an ultimate strength of 265 +/- 17 MPa. Examination of fracture surfaces revealed limited short length fiber pull-out. From fiber push-out, the fiber/matrix interfacial debonding and frictional strengths were evaluated to be approx. 17.5 +/- 2.7 MPa and 11.3 +/- 1.6 MPa, respectively. Some fibers were strongly bonded to the matrix and could not be pushed out. The micromechanical models were not useful in predicting values of the first matrix cracking stress as well as the ultimate strength of the composites.

  16. Life Limiting Behavior in Interlaminar Shear of Continuous Fiber-Reinforced Ceramic Matrix Composites at Elevated Temperatures

    Science.gov (United States)

    Choi, Sung R.; Calomino, Anthony M.; Bansal, Narottam P.; Verrilli, Michael J.

    2006-01-01

    Interlaminar shear strength of four different fiber-reinforced ceramic matrix composites was determined with doublenotch shear test specimens as a function of test rate at elevated temperatures ranging from 1100 to 1316 C in air. Life limiting behavior, represented as interlaminar shear strength degradation with decreasing test rate, was significant for 2-D crossplied SiC/MAS-5 and 2-D plain-woven C/SiC composites, but insignificant for 2-D plain-woven SiC/SiC and 2-D woven Sylramic (Dow Corning, Midland, Michigan) SiC/SiC composites. A phenomenological, power-law delayed failure model was proposed to account for and to quantify the rate dependency of interlaminar shear strength of the composites. Additional stress rupture testing in interlaminar shear was conducted at elevated temperatures to validate the proposed model. The model was in good agreement with SiC/MAS-5 and C/SiC composites, but in poor to reasonable agreement with Sylramic SiC/SiC. Constant shear stress-rate testing was proposed as a possible means of life prediction testing methodology for ceramic matrix composites subjected to interlaminar shear at elevated temperatures when short lifetimes are expected.

  17. Kinetics of formation of a platelet-reinforced ceramic composite prepared by the directed reaction of zirconium with boron carbide

    International Nuclear Information System (INIS)

    In this paper the kinetics of formation of a new class of ceramic composite material, zirconium diboride platelet-reinforced zirconium carbides, are discussed. These materials are prepared by the directed reaction of molten zirconium with boron carbide to form a ceramic material composed of zirconium diboride platelets approximately uniformly distributed in a zirconium carbide matrix containing a controlled amount of residual zirconium metal. Results from interrupted growth studies, differential thermal analysis, adiabatic reaction temperature calculations, and kinetic measurements have been used to study the kinetics of the process. The reaction is very fast and proceeds parabolically with time with a rate constant between 1.6 x 10-2 and 3.9 x 10-2 cm2/s. The proposed mechanism suggests that when molten zirconium contacts boron carbide, the molten zirconium exothermically reacts with the boron carbide to form a boron-rick liquid. Further reaction is sustained by the continuous dissolution of the boron carbide as the boron-rich liquid is drawn into the boron carbide. The product is a zirconium diboride/zirconium carbide/zirconium composite which homogenizes quickly at the reaction temperature to yield a uniform product microstructure throughout the composite. Two alternative rate-limiting steps are discussed and the implications of each are explored

  18. Fracture Toughness of Carbon Nanotube-Reinforced Metal- and Ceramic-Matrix Composites

    Directory of Open Access Journals (Sweden)

    Y. L. Chen

    2011-01-01

    Full Text Available Hierarchical analysis of the fracture toughness enhancement of carbon nanotube- (CNT- reinforced hard matrix composites is carried out on the basis of shear-lag theory and facture mechanics. It is found that stronger CNT/matrix interfaces cannot definitely lead to the better fracture toughness of these composites, and the optimal interfacial chemical bond density is that making the failure mode just in the transition from CNT pull-out to CNT break. For hard matrix composites, the fracture toughness of composites with weak interfaces can be improved effectively by increasing the CNT length. However, for soft matrix composite, the fracture toughness improvement due to the reinforcing CNTs quickly becomes saturated with an increase in CNT length. The proposed theoretical model is also applicable to short fiber-reinforced composites.

  19. High Temperature Erosion Wear of Cermet Particles Reinforced Self-Fluxing Alloy HVOF Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Andrei SURZHENKOV

    2015-09-01

    Full Text Available The resistance of high velocity oxy-fuel (HVOF sprayed TiC-NiMo and Cr3C2-Ni cermet particles reinforced NiCrSiB self-fluxing alloy coatings to high temperature erosion wear was studied. Microstructure of the coatings was examined by SEM, phase composition was determined by XRD. A four-channel centrifugal particle accelerator was applied to study the high temperature erosion wear of the coatings. The angles of impingement were 30º and 90º, initial particle velocity was 50 m/s, the average temperature of the test – 650 ºC. Volume wear of the coatings was calculated and compared to the respective values of the reference materials. Wear mechanisms were studied by SEM. HVOF sprayed coatings exhibited lower wear, than WC-15Co hardmetal and steel HARDOX 400, but higher wear than steel AISI 304. TiC-NiMo particles reinforced self-fluxing alloy coating demonstrated virtually the same wear resistance, as the Cr3C2-Ni particles reinforced self-fluxing alloy coating, at 30º and the better wear resistance at 90º.

  20. Bio-composites based on polypropylene reinforced with Almond Shells particles: Mechanical and thermal properties

    International Nuclear Information System (INIS)

    Highlights: • Almond Shells (ASs) particles have been used as reinforcement in polypropylene matrix. • The SEBS-g-MA has been used to improve the adhesion between matrix and particles. • The mechanical and thermal properties of the composite have been improved by the AS. - Abstract: In this work, Almond Shells (ASs) particles are used as reinforcement in a thermoplastic matrix as polypropylene (PP). Composites containing Almond Shells (ASs) particles with and without compatibilizer (maleic anhydride grafted polypropylene; SEBS-g-MA) for various particle content (5, 10, 15, 20, 25, 30 wt.%) was investigated by means of studying their mechanical, thermal and rheological properties. The composites were prepared in a twin-screw extruder and assessed by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), tensile testing and Dynamic Mechanical Analysis (DMA). Results show a clear improvement in mechanical and rheological properties from the use of Almond Shells particles in the matrix without and with maleic anhydride compatibilizer, corresponding to a gain in Young’s modulus of 56.2% and 35% respectively, at 30 wt.% particle loading. Thermal analysis revealed that incorporation of particle in the composites resulted in increase in the initial thermal decomposition temperatures

  1. Intermediate-temperature environmental effects on boron nitride-coated silicon carbide-fiber-reinforced glass-ceramic composites

    International Nuclear Information System (INIS)

    The environmental effects on the mechanical properties of fiber-reinforced composites at intermediate temperatures were investigated by conducting flexural static-fatigue experiments in air at 600 and 950 C. The material that was studied was a silicon carbide/boron nitride (SiC/BN) dual-coated Nicalon-fiber-reinforced barium magnesium aluminosilicate glass-ceramic. Comparable time-dependent failure responses were found at 600 and 950 C when the maximum tensile stress applied in the bend bar was >60% of the room-temperature ultimate flexural strength of as-received materials. At both temperatures, the materials survived 500 h fatigue tests at lower stress levels. Among the samples that survived the 500 h fatigue tests, a 20% degradation in the room temperature flexural strength was measured in samples that were fatigued at 600 C. The growth rate of the Si-C-O fiber oxidation product at 600 C was not sufficient to seal the stress-induced cracks, so that the interior of the material was oxidized and resulted in a strength degradation and less fibrous fracture. In contrast, the interior of the material remained intact at 950 C because of crack sealing by rapid silicate formation, and strength/toughness of the composite was maintained. Also, at 600 C, BN oxidized via volatilization, because no borosilicate was formed

  2. Relationship Between Hysteresis Dissipated Energy and Temperature Rising in Fiber-Reinforced Ceramic-Matrix Composites Under Cyclic Loading

    Science.gov (United States)

    Longbiao, Li

    2015-09-01

    In this paper, the relationship between hysteresis dissipated energy and temperature rising of the external surface in fiber-reinforced ceramic-matrix composites (CMCs) during the application of cyclic loading has been analyzed. The temperature rise, which is caused by frictional slip of fibers within the composite, is related to the hysteresis dissipated energy. Based on the fatigue hysteresis theories considering fibers failure, the hysteresis dissipated energy and a hysteresis dissipated energy-based damage parameter changing with the increase of cycle number have been investigated. The relationship between the hysteresis dissipated energy, a hysteresis dissipated energy-based damage parameter and a temperature rise-based damage parameter have been established. The experimental temperature rise-based damage parameter of unidirectional, cross-ply and 2D woven CMCs corresponding to different fatigue peak stresses and cycle numbers have been predicted. It was found that the temperature rise-based parameter can be used to monitor the fatigue damage evolution and predict the fatigue life of fiber-reinforced CMCs.

  3. Microstructural analysis and mechanical characterization of aluminum matrix nanocomposites reinforced with uncoated and Cu-coated alumina particles

    International Nuclear Information System (INIS)

    Aluminum matrix composites used in the aerospace, military and automotive industries are typically fabricated by a stir casting method. However, when nanoparticles are used for reinforcement, fabrication of composite materials by this method leads to the formation of a large number of structural defects. In this study, copper coating of alumina reinforcement particles is investigated as a technique for improving the structure of Al-Al2O3 composites. Microstructural investigations by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersion spectroscopy (EDS) and transmission electron microscopy (TEM) showed that the alumina particles were coated uniformly with copper shells. Copper coating of the reinforcing particles significantly increased their wettability in the molten aluminum alloy, strengthened the matrix-particle interfaces and improved the distribution of reinforcing particles within the matrix. Due to these microstructural improvements, the hardness, compressive strength, yield stress, tensile strength and elongation of the composites were enhanced by copper coating of the alumina particles

  4. Plasma in spark plasma sintering of ceramic particle compacts

    OpenAIRE

    Marder, Rachel; Estournès, Claude; Chevallier, Geoffroy; Chaim, Rachman

    2014-01-01

    Cuboidal LiF microcrystal powder was densified by spark plasma sintering at different pressures up to 500 °C. Densification at pressures above the yield stress occurred by plastic deformation and strain hardening. Densification at 2 MPa, below the yield stress, occurred by particle rearrangement assisted by viscous flow at the particle surfaces. Scanning electron microscopy examination of the fracture surfaces of the partially dense specimens revealed partial melting of the particle surfaces ...

  5. Structure and properties of porous ceramic preforms made of α-alumina particles

    Directory of Open Access Journals (Sweden)

    J. W. Kaczmar

    2010-01-01

    Full Text Available Properties of ceramic preforms made of α-alumina particles for strengthening of metal based composite materials manufactured by squeeze casting are discussed in the paper. Composite materials strengthened with ceramic particles can be then plastically worked in order to remove the residual porosity and give the final net shape. There was investigated the permeability of porous preforms as the measure of the open porosity making possible the infiltration process with the molten metal, compression strength, bending strength and shear strength determining the stability of porous ceramic preforms during infiltration. Performed investigations allow to ascertain the occurrence of the open porosity in the porous preforms and strong effect of porosity on permeability. The largest permeability of 19 m2/Pa·s showed porous preforms characterized by porosity the of 90%. The strength properties increased with the decrease of preforms porosity and the prerforms characterized by 60% of porosity were characterized by the largest strength properties (bending strength Rg =7 MPa, compression strength Rc = 11.5 MPa, shear strength Rt = 4.0 MPa. The microscopic observations of fractures surfaces allow to evaluate quality and forming phenomena of the binder bridges connecting the ceramic particles.

  6. TEM investigations of Al 6061 and of composites reinforced with Al[sub 2]O[sub 3] particles

    Energy Technology Data Exchange (ETDEWEB)

    Mingler, B. (Inst. fuer Festkoerperphysik, Univ. Vienna (Austria)); Karnthaler, H.P. (Inst. fuer Festkoerperphysik, Univ. Vienna (Austria))

    1993-05-01

    The Al alloy 6061 and metal matrix composites (MMC) of the same alloy as matrix, reinforced with particulate Al[sub 2]O[sub 3] (10 and 20 vol.%), were investigated by transmission electron microscopy (TEM) methods after both heat treatments T5 and T6. Al 6061 shows similar mechanical data (yield strength, tensile strength) after both heat treatments whereas after T5 heat treatment the MMC show a lower strength than after T6 heat treatment. A homogeneous distribution of fine precipitates (Mg[sub 2]Si Guinier-Preston zones) was found throughout the specimen after T6 heat treatment in the alloy Al 6061 and in the matrix of the MMC. Contrary to this, precipitation-free zones (PFZ) were observed after the T5 heat treatment in both Al 6061 and the MMC. The PFZ occur along grain boundaries (about 200 nm wide) and in addition in the MMC around the ceramic particles in the areas of high dislocation densities (about 700 nm wide). (orig.)

  7. Zirconia-coated carbonyl-iron-particle-based magnetorheological fluid for polishing optical glasses and ceramics

    International Nuclear Information System (INIS)

    We report on magnetorheological finishing (MRF) spotting experiments performed on glasses and ceramics using a zirconia-coated carbonyl-iron (CI)-particle-based magnetorheological (MR) fluid. The zirconia-coated magnetic CI particles were prepared via sol-gel synthesis in kilogram quantities. The coating layer was ∼50-100 nm thick, faceted in surface structure, and well adhered. Coated particles showed long-term stability against aqueous corrosion. ''Free'' nanocrystalline zirconia polishing abrasives were cogenerated in the coating process, resulting in an abrasive-charged powder for MRF. A viable MR fluid was prepared simply by adding water. Spot polishing tests were performed on a variety of optical glasses and ceramics over a period of nearly three weeks with no signs of MR fluid degradation or corrosion. Stable material removal rates and smooth surfaces inside spots were obtained.

  8. Zirconia-coated carbonyl-iron-particle-based magnetorheological fluid for polishing optical glasses and ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Shafrir, Shai N.; Romanofsky, Henry J.; Skarlinski, Michael; Wang, Mimi; Miao, Chunlin; Salzman, Sivan; Chartier, Taylor; Mici, Joni; Lambropoulos, John C.; Shen Rui; Yang Hong; Jacobs, Stephen D.

    2009-12-10

    We report on magnetorheological finishing (MRF) spotting experiments performed on glasses and ceramics using a zirconia-coated carbonyl-iron (CI)-particle-based magnetorheological (MR) fluid. The zirconia-coated magnetic CI particles were prepared via sol-gel synthesis in kilogram quantities. The coating layer was {approx}50-100 nm thick, faceted in surface structure, and well adhered. Coated particles showed long-term stability against aqueous corrosion. ''Free'' nanocrystalline zirconia polishing abrasives were cogenerated in the coating process, resulting in an abrasive-charged powder for MRF. A viable MR fluid was prepared simply by adding water. Spot polishing tests were performed on a variety of optical glasses and ceramics over a period of nearly three weeks with no signs of MR fluid degradation or corrosion. Stable material removal rates and smooth surfaces inside spots were obtained.

  9. Celsian formation in fiber-reinforced barium aluminosilicate glass-ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, Narottam P

    2003-02-15

    Hot pressing of barium aluminosilcate (BAS) glass or its composites reinforced with large diameter Textron chemical vapor deposited (CVD) silicon carbide SCS-6 monofilaments or small diameter multifilament Nicalon or Hi-Nicalon fibers resulted in the crystallization of both hexacelsian and monoclinic celsian phases. Effects of additions of monoclinic celsian seeds and strontium aluminosilicate (SAS) glass on crystal phase formation during hot pressing has been investigated. On doping BAS with 5 wt.% monoclinic celsian seeds or 10 wt.% SAS, only the celsian phase was formed in hot pressed monolithic specimens. However, in fiber-reinforced composites hot pressed under similar conditions, a small concentration of hexacelsian was still present as hexacelsian nucleates preferentially on surfaces and the presence of fibers provides a large surface area. When the additive concentration was increased to 10 wt.% celsian seeds or 20 wt.% SAS, celsian was the only phase detected from X-ray diffraction, with complete elimination of hexacelsian, in the hot pressed composites reinforced with large or small diameter SiC fibers.

  10. Celsian formation in fiber-reinforced barium aluminosilicate glass-ceramic matrix composites

    International Nuclear Information System (INIS)

    Hot pressing of barium aluminosilcate (BAS) glass or its composites reinforced with large diameter Textron chemical vapor deposited (CVD) silicon carbide SCS-6 monofilaments or small diameter multifilament Nicalon or Hi-Nicalon fibers resulted in the crystallization of both hexacelsian and monoclinic celsian phases. Effects of additions of monoclinic celsian seeds and strontium aluminosilicate (SAS) glass on crystal phase formation during hot pressing has been investigated. On doping BAS with 5 wt.% monoclinic celsian seeds or 10 wt.% SAS, only the celsian phase was formed in hot pressed monolithic specimens. However, in fiber-reinforced composites hot pressed under similar conditions, a small concentration of hexacelsian was still present as hexacelsian nucleates preferentially on surfaces and the presence of fibers provides a large surface area. When the additive concentration was increased to 10 wt.% celsian seeds or 20 wt.% SAS, celsian was the only phase detected from X-ray diffraction, with complete elimination of hexacelsian, in the hot pressed composites reinforced with large or small diameter SiC fibers

  11. Study of Mechanical Characteristics for Polymer Composite Reinforced by Particles of (Al2O3 or (Al

    Directory of Open Access Journals (Sweden)

    Saad M. elIa

    2007-01-01

    Full Text Available A particulate polymer composite material was prepared by reinforcing with the Aluminum Oxide (Al2O3 or Aluminum (Al metallic particles with a particle size of (30 µm to an unsaturated Polyester Resin with a weight fraction of (5%, 10%, 15%, 20%. Tensile test results showed the maximum value of elastic modulus reached (2400MPa. in the case of reinforcing with (Al particles with weight fraction (20% and (1500 MPa. in the case of reinforcing with (Al2O3 particles of the same weight fraction. When the impact and the flexural strength tests were done, the results showed that flexural strength (F.S, maximum shear stress (?max, impact strength (Gc and fracture toughness (Kc were increased with the increase of weight fraction, where the results of the samples of (Al particles were higher than that of (Al2O3 particles reinforced at a weight fraction of (20% at ratios of (45.43%, 45.45%, 25%, 41% respectively. While the hardness of the samples reinforced with (Al2O3 particles was higher than that reinforced with (Al particles with a ratio of (2.82% at a weight fraction of (20%.

  12. Influence of thermal residual stress on behaviour of metal matrix composites reinforced with particles

    Science.gov (United States)

    Guzmán, R. E.; Hernández Arroyo, E.

    2016-02-01

    The properties of a metallic matrix composites materials (MMC's) reinforced with particles can be affected by different events occurring within the material in a manufacturing process. The existence of residual stresses resulting from the manufacturing process of these materials (MMC's) can markedly differentiate the curves obtained in tensile tests obtained from compression tests. One of the themes developed in this work is the influence of residual stresses on the mechanical behaviour of these materials. The objective of this research work presented is numerically estimate the thermal residual stresses using a unit cell model for the Mg ZC71 alloy reinforced with SiC particles with volume fraction of 12% (hot-forging technology). The MMC's microstructure is represented as a three dimensional prismatic cube-shaped with a cylindrical reinforcing particle located in the centre of the prism. These cell models are widely used in predicting stress/strain behaviour of MMC's materials, in this analysis the uniaxial stress/strain response of the composite can be obtained through the calculation using the commercial finite-element code.

  13. Deformation behavior of SiC particle reinforced Al matrix composites based on EMA model

    Institute of Scientific and Technical Information of China (English)

    CHENG Nan-pu; ZENG Su-min; YU Wen-bin; LIU Zhi-yi; CHEN Zhi-qian

    2007-01-01

    Effects of the matrix properties, particle size distribution and interfacial matrix failure on the elastoplastic deformation behavior in Al matrix composites reinforced by SiC particles with an average size of 5 μm and volume fraction of 12% were quantitatively calculated by using the expanded effective assumption(EMA) model. The particle size distribution naturally brings about the variation of matrix properties and the interfacial matrix failure due to the presence of SiC particles. The theoretical results coincide well with those of the experiment. The current research indicates that the load transfer between matrix and reinforcements, grain refinement in matrix, and enhanced dislocation density originated from the thermal mismatch between SiC particles and Al matrix increase the flow stress of the composites, but the interfacial matrix failure is opposite. It also proves that the load transfer, grain refinement and dislocation strengthening are the main strengthening mechanisms, and the interfacial matrix failure and ductile fracture of matrix are the dominating fracture modes in the composites. The mechanical properties of the composites strongly depend on the metal matrix.

  14. Modeling of Size-Dependent Strengthening in Particle-Reinforced Aluminum Composites with Strain Gradient Plasticity

    International Nuclear Information System (INIS)

    This study proposes finite element modeling of dislocation punching at cooling after consolidation in order to calculate the strength of particle-reinforced aluminum composites. The Taylor dislocation model combined with strain gradient plasticity around the reinforced particle is adopted to take into account the size-dependency of different volume fractions of the particle. The strain gradients were obtained from the equivalent plastic strain calculated during the cooling of the spherical unit cell, when the dislocation punching due to CTE (Coefficient of Thermal Expansion) mismatch is activated. The enhanced yield stress was observed by including the strain gradients, in an average sense, over the punched zone. The tensile strength of the SiCp/Al 356-T6 composite was predicted through the finite element analysis of an axisymmetric unit cell for various sizes and volume fractions of the particle. The predicted strengths were found to be in good agreement with the experimental data. Further, the particle-size dependency was clearly established

  15. Preparation and biocompatibility of poly (methyl methacrylate reinforced with bioactive particles

    Directory of Open Access Journals (Sweden)

    Pereira Marivalda de Magalhães

    2003-01-01

    Full Text Available Calcium phosphates and bioactive glasses have been used in many biomedical applications for more than 30 years due basically to their bioactive behavior. However, ceramics are too brittle for applications that require high levels of toughness and easy processability. In this work, a biphasic calcium phosphate (BCP and a bioactive glass composition (BG were combined with polymers to produce composites with tailorable properties and processability. The BCP particles were synthesized by a precipitation technique. The BG particles were produced by sol-gel processing. The BCP particles were treated with a silane agent to improve the compatibility between particles and the polymer matrix. Dense samples were produced by hot pressing (200 °C a mixture of 30 wt.% of particles in poly (methyl methacrylate. The samples produced were characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Mechanical properties were evaluated by a three point bending test. Samples were also submitted to in vitro bioactivity test and in vivo toxicity test. Results showed that the production of the composites was successfully achieved, yielding materials with particles well dispersed within the matrices. Evaluation of the in vivo inflammatory response showed low activity levels for all composites although composites with silane treated BCP particles led to milder inflammatory responses than composites with non-treated particles.

  16. Mechanical strength of ceramic scaffolds reinforced with biopolymers is comparable to that of human bone

    DEFF Research Database (Denmark)

    Henriksen, S S; Ding, M; Vinther Juhl, M;

    2011-01-01

    Eight groups of calcium-phosphate scaffolds for bone implantation were prepared of which seven were reinforced with biopolymers, poly lactic acid (PLA) or hyaluronic acid in different concentrations in order to increase the mechanical strength, without significantly impairing the microarchitecture....... The increase in mechanical strength was seen as a result of increased scaffold thickness and changes to plate-like structure. However, the porosity was significantly lowered as a consequence of adding 15% PLA, whereas adding 10% PLA had no significant effect on porosity. Hyaluronic acid had no...

  17. Mechanical and electrical properties of polymer-derived Si-C-N ceramics reinforced by octadecylamine ? modified single-wall carbon nanotubes

    OpenAIRE

    Shopova-Gospodinova, D.; Burghard, Z.; Dufaux, T.; Burghard, M; Bill, J

    2011-01-01

    Abstract Polymer-derived Si-C-N ceramics reinforced by homogeneously distributed octadecylamine?functionalized single-walled carbon nanotubes (SWCNTs) were synthesized using a casting process, successive pressureless cross-linking and thermolysis. We find that the incorporation of even small amounts of modified SWCNTs leads to a remarkable improvement of mechanical and electrical transport properties of our composites. In particular, we find two-fold enhancement of fracture toughne...

  18. Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

    Science.gov (United States)

    Guo, Zhanhu; Park, Sung; Wei, Suying; Pereira, Tony; Moldovan, Monica; Karki, Amar B.; Young, David P.; Hahn, H. Thomas

    2007-08-01

    Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions.

  19. Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

    International Nuclear Information System (INIS)

    Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions

  20. Aluminium based composites strengthened with metallic amorphous phase or ceramic (Al2O3) particles

    International Nuclear Information System (INIS)

    Highlights: • Al-based composites with amorphous Al strengthening phase were obtained. • A better adhesion of metallic amorphous particles than of ceramic phase. • Avoiding crystallization of amorphous phase during a composite pressing process. • Properties similar for 10% metallic amorphous and ceramic strengthening phases. • Better amorphization in case of melt spinning than gas atomization of the Al alloy. - Abstract: Two methods were used to obtain amorphous aluminium alloy powder: gas atomization and melt spinning. The sprayed powder contained only a small amount of the amorphous phase and therefore bulk composites were prepared by hot pressing of aluminium powder with the 10% addition of ball milled melt spun ribbons of the Al84Ni6V5Zr5 alloy (numbers indicate at.%). The properties were compared with those of a composite containing a 10% addition of Al2O3 ceramic particles. Additionally, a composite based on 2618A Al alloy was prepared with the addition of the Al84Ni6V5Zr5 powder from the ribbons used as the strengthening phase. X-ray studies confirmed the presence of the amorphous phase with a small amount of aluminium solid solution in the melt spun ribbons. Differential Scanning Calorimetry (DSC) studies showed the start of the crystallization process of the amorphous ribbons at 437 °C. The composite samples were obtained in the process of uniaxial hot pressing in a vacuum at 380 °C, below the crystallization temperature of the amorphous phase. A uniform distribution of both metallic and ceramic strengthening phases was observed in the composites. The hardness of all the prepared composites was comparable and amounted to approximately 50 HV for those with the Al matrix and 120 HV for the ones with the 2618A alloy matrix. The composites showed a higher yield stress than the hot pressed aluminium or 2618A alloy. Scanning Electron Microscopy (SEM) studies after compression tests revealed that the propagation of cracks in the composites

  1. Friction and Wear of Monolithic and Fiber Reinforced Silicon-Ceramics Sliding Against IN-718 Alloy at 25 to 800 C in Atmospheric Air at Ambient Pressure

    Science.gov (United States)

    Deadmore, Daniel L.; Sliney, Harold E.

    1988-01-01

    The friction and wear of monolithic and fiber reinforced Si-ceramics sliding against the nickel base alloy IN-718 at 25 to 800 C was measured. The monolithic materials tested were silicon carbide (SiC), fused silica (SiO2), syalon, silicon nitride (Si3N4) with W and Mg additives, and Si3N4 with Y2O3 additive. At 25 C fused silica had the lowest friction while Si3N4 (W,Mg type) had the lowest wear. At 800 C syalon had the lowest friction while Si3N4 (W,Mg type) and syalon had the lowest wear. The SiC/IN-718 couple had the lowest total wear at 25 C. At 800 C the fused silica/IN-718 couple exhibited the least total wear. SiC fiber reinforced reaction bonded silicon nitride (RBSN) composite material with a porosity of 32 percent and a fiber content of 23 vol percent had a lower coefficient of friction and wear when sliding parallel to the fiber direction than in the perpendicular at 25 C. The coefficient of friction for the carbon fiber reinforced borosilicate composite was 0.18 at 25 C. This is the lowest of all the couples tested. Wear of this material was about two decades smaller than that of the monolithic fused silica. This illustrates the large improvement in tribological properties which can be achieved in ceramic materials by fiber reinforcement. At higher temperatures the oxidation products formed on the IN-718 alloy are transferred to the ceramic by sliding action and forms a thin, solid lubricant layer which decreases friction and wear for both the monolithic and fiber reinforced composites.

  2. Preparation, microstructural evolution and properties of Ni–Zr intermetallic/Zr–Si ceramic reinforced composite coatings on zirconium alloy by laser cladding

    International Nuclear Information System (INIS)

    NiZr2–ZrSi–Zr5(SixNi1−x)4-ZrC intermetallic/ceramic reinforced composite coatings were in situ synthesized by laser cladding the pre-placed Ni–Cr–B–Si powder on zirconium substrate. Microstructure and phase constituents were investigated by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Microhardness tester and block-on-ring wear tester were employed to measure the hardness distribution and wear resistance of the intermetallic/ceramic reinforced composite coating. Results indicated that the multiphase of reinforcements includes Ni–Zr intermetallic compounds (e.g., NiZr and NiZr2) and Zr–Si(C) ceramic phases (e.g., ZiSi, Zr5Si4 and ZrC). Ni–Si clusters transforming to Zr–Si–Ni clusters at high temperature facilitated the forming of Zr5(SixNi1−x)4 and during the growth of Zr5(SixNi1−x)4, the consumption of Zr atoms at the lateral interface of liquid/Zr5(SixNi1−x)4 resulted into developing Zr-poor zone near Zr5(SixNi1−x)4. The microhardness and wear resistance of the coating were significantly improved by various reinforced phases in comparison to zirconium substrate. - Highlights: • NiZr2–ZrSi–Zr5(SixNi1−x)4-ZrC compostie coating was in-situ synthesized. • Ni–Si clusters transforming resulted into developing Zr-poor zone near Zr5(SixNi1−x)4. • Reinforced phases significantly improve wear resistance of the coating

  3. The characteristics and application of sludge-fly ash ceramic particles (SFCP) as novel filter media

    International Nuclear Information System (INIS)

    Novel filter media-sludge-fly ash ceramic particles (SFCP) were prepared using dewatered sludge, fly ash and clay with a mass ratio of 1:1:1. Compared with commercial ceramic particles (CCP), SFCP had higher total porosity, larger total surface area and lower bulk and apparent density. Tests of heavy metal elements in lixivium proved that SFCP were safe for wastewater treatment. A lab-scale upflow anaerobic bioreactor was employed to ascertain the application of SFCP in denitrification process using acetate as carbon source. The results showed that SFCP reactor brought a relative superiority to CCP reactor in terms of total nitrogen (TN) removal at the optimum C/N ratio of 4.03 when volumetric loading rates (VLR) ranged from 0.33 to 3.69 kg TN (m3 d)-1. Therefore, SFCP application, as a novel process of treating wastes with wastes, provided a promising way in sludge and fly ash utilization.

  4. Progressive failure processes of reinforced slopes based on general particle dynamic method

    Institute of Scientific and Technical Information of China (English)

    赵毅; 周小平; 钱七虎

    2015-01-01

    In order to resolve grid distortions in finite element method (FEM), the meshless numerical method which is called general particle dynamics (GPD) was presented to simulate the large deformation and failure of geomaterials. The Mohr-Coulomb strength criterion was implemented into the code to describe the elasto-brittle behaviours of geomaterials while the solid-structure (reinforcing pile) interaction was simulated as an elasto-brittle material. The Weibull statistical approach was applied to describing the heterogeneity of geomaterials. As an application of general particle dynamics to slopes, the interaction between the slopes and the reinforcing pile was modelled. The contact between the geomaterials and the reinforcing pile was modelled by using the coupling condition associated with a Lennard-Jones repulsive force. The safety factor, corresponding to the minimum shear strength reduction factor “R”, was obtained, and the slip surface of the slope was determined. The numerical results are in good agreement with those obtained from limit equilibrium method and finite element method. It indicates that the proposed geomaterial-structure interaction algorithm works well in the GPD framework.

  5. Nanopore fabrication by heating Au particles on ceramic substrates.

    Science.gov (United States)

    de Vreede, Lennart J; van den Berg, Albert; Eijkel, Jan C T

    2015-01-14

    We found that gold nanoparticles, when heated to close to their melting point on substrates of amorphous SiO2 or amorphous Si3N4, move perpendicularly into the substrate. Dependent on applied temperatures, particles can become buried or leave nanopores of extreme aspect ratio (diameter ≅ 25 nm, length up to 800 nm). The process can be understood as driven by gold evaporation and controlled by capillary forces and can be controlled by temperature programming and substrate choice. PMID:25548953

  6. The Microstructure and Hardness Properties Analysis of Welded Aluminum Matrix Material Reinforced with SiC Using Different Currents and Forms of Welding

    OpenAIRE

    Arzum Ulukoy; Volkan Onar; Yavuz Kaplan

    2015-01-01

    The welding of metal matrix material reinforced with ceramic particles has some problems such as formation of oxide layer, segregation occurring on welding area, and reaction of ceramic particles with welding bath. The expected mechanical properties cannot be obtained because of these problems. In this study, the weldability of aluminum 2014 alloy reinforced with SiC particles was investigated. MIG welding process was used via using AlSi5 alloy wire at different types and values of welding cu...

  7. Mechanical and thermal properties of phthalonitrile resin reinforced with silicon carbide particles

    International Nuclear Information System (INIS)

    Highlights: • SiC microparticles improve the mechanical properties of phthalonitrile resin. • Excellent thermal stability achieved by adding SiC particles in phthalonitrile resin. • Adding 20 wt.% of SiC microparticles increases the Tg by 38 °C. • Silane coupling agent can enhance the adhesion and dispersion of particles/matrix. - Abstract: A new type of composite based on phthalonitrile resin reinforced with silicon carbide (SiC) microparticles was prepared. For various weight ratios ranging between 0% and 20%, the effect of the micro-SiC particles on the mechanical and thermal properties has been studied. Results from thermal analysis revealed that the starting decomposition temperature and the residual weight were significantly improved upon adding the reinforcing phase. At the maximum micro-SiC loading, dynamic mechanical analysis (DMA) showed an important enhancement in both the storage modulus and glass transition temperature (Tg), reaching 3.1 GPa and 338 °C, respectively. The flexural strength and modulus as well as the microhardness were significantly enhanced by adding the microfillers. Tensile test revealed enhancements in the composites toughness upon adding the microparticles. Polarization optical microscope (POM) and scanning electron microscope (SEM) analysis confirmed that mechanical and thermal properties improvements are essentially attributed to the good dispersion and adhesion between the particles and the resin

  8. Oxidation behavior of TiC particle-reinforced 304 stainless steel

    International Nuclear Information System (INIS)

    TiC particle-reinforced 304 stainless steels were prepared using a new developed in situ technology and exhibited the uniform distribution of TiC particles in the matrix. The oxidation behavior of 304SS-2TiC and 304SS-6TiC (all in weight percentage) was compared with that of 304SS at 850 deg. C in air for 96 h using thermogravimetry analysis. For 304SS, the rate of weight gain was very slow initially, but accelerated suddenly to a very high level, forming breakaway oxidation. The addition of TiC particles to 304SS resulted in no breakaway oxidation and maintained a low oxidation rate in the whole reaction time investigated. Examination of oxide scale morphology and cross-section analysis by scanning electron microscopy and optical microscopy showed a significant scale spallation and a deep oxide penetration in the case of 304SS, but a rather continuous, dense and adherent oxide layer formed on the surface of TiC particle-reinforced alloys. XRD analysis revealed the presence of Cr2O3 together with spinel-type oxides in the oxide scale. For TiC-containing alloys, fine TiO2 was also found on the surface and the amount of this oxide increased with TiC addition. The TiC addition developed finer matrix structure before oxidation, which accelerates chromium diffusion. As a result, scale adherence was improved and oxidation resistance was increased.

  9. Microstructural characterization and mechanical properties of self-reinforced Si3N4 ceramics containing high oxynitride glass

    Institute of Scientific and Technical Information of China (English)

    Xuetao Luo; Lifu Chen; Qianjun Huang; Litong Zhang

    2004-01-01

    Self-reinforced Si3N4 ceramics containing high oxynitride glass have been fabricated by the control of microstructure evolution and a-Si3N4 grain growth. The effects of the size distribution of the elongated a-Si3N4 grains, and the a-Si3N4 grain growth as well as the oxynitride glass chemical characteristic on the microstructure and mechanical properties were investigated. The experimental results show that the a-Si3N4 grains in high oxynitride glass grow to elongated rod-like crystals and form the stereo-network structure. Under the sintering conditions of 1800℃ and 60 min, a quite uniform microstructure with an average aspect ratio of 6.5temperature fracture toughness because of its high softening temperature and high viscosity. In the present material, the crack deflection and pullout of the elongated rod-like a-Si3N4 grains are the primary toughening mecl anisms.

  10. Effects of Temperature, Oxidation and Fiber Preforms on Fatigue Life of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    Science.gov (United States)

    Longbiao, Li

    2016-04-01

    In this paper, the effects of temperature, oxidation and fiber preforms on the fatigue life of carbon fiber-reinforced silicon carbide ceramic-matrix composites (C/SiC CMCs) have been investigated. An effective coefficient of the fiber volume fraction along the loading direction (ECFL) was introduced to describe the fiber architecture of preforms. Under cyclic fatigue loading, the fibers broken fraction was determined by combining the interface wear model and fibers statistical failure model at room temperature, and interface/fibers oxidation model, interface wear model and fibers statistical failure model at elevated temperatures in the oxidative environments. When the broken fibers fraction approaches to the critical value, the composites fatigue fracture. The fatigue life S-N curves and fatigue limits of unidirectional, cross-ply, 2D, 2.5D and 3D C/SiC composites at room temperature, 800 °C in air, 1100, 1300 and 1500 °C in vacuum conditions have been predicted.

  11. An historical mullite fiber-reinforced ceramic composite: Characterization of the wootz' crucible refractory

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, T.L. (California Univ., Berkeley, CA (USA)); Merk, N.; Thomas, G. (Lawrence Berkeley Lab., CA (USA))

    1990-10-01

    Since at least the sixteenth century, the wootz'' ultra-high carbon white cast-iron ingot was produced in India by melting or carburising iron in a crucible. This ingot was forced into sword blades of so-called Damascus steel. The charged crucible was fired in a long (24-hour) single cycle at high temperature (1150-1250{degree}C) in a strongly reducing atmosphere. Raw materials for the refractory vessel are clay and coked'' rice husks. At high temperatures, two phases reinforce the glassy matrix: cristobalite relics of rice husks and a network of mullite crystals. This paper characterizes the microstructure and chemistry of the mullite network in the glassy matrix by means of a combination of techniques: optical microscopy, XRD, SEM, TEM and EDS, and HREM. 13 refs., 11 figs.

  12. Orientation of platelet reinforcements in ceramic matrix composites produced by pressure filtration

    International Nuclear Information System (INIS)

    Alumina-platelet (Al2O3(PL)) reinforced Y-TZP composites were produced by pressure filtration of dispersed suspensions. The platelet texture within the consolidated compacts was evaluated by SEM and neutron diffraction to assess the effects of pressing rate, constant rate versus constant displacement filtration, and die loading on platelet orientation. A weak texture condition, termed 'eddy texturing' due to an apparent dependence on fluid flow during filtration, dominated platelet orientation. The resulting composites possessed an anisotropic fracture toughness between the compact surfaces and the bulk material. Die loading procedure and Al2O3(PL) agglomerate removal strongly influenced the density and flexural strength of the sintered composites. 9 refs

  13. Characterization of aluminium matrix composites reinforced by Al–Cu–Fe quasicrystalline particles

    Energy Technology Data Exchange (ETDEWEB)

    Lityńska-Dobrzyńska, L.; Dutkiewicz, J.; Stan-Głowińska, K.; Wajda, W. [Institute of Metallurgy and Materials Science Polish Academy of Sciences, 30-059 Kraków, 25 Reymonta St. (Poland); Dembinski, L.; Langlade, C.; Coddet, C. [Universite de Technologie de Belfort-Montbeliard, Site de Sevenans 90010, Belfort (France)

    2015-09-15

    Highlights: • Al powder and atomised Al{sub 65}Cu{sub 20}Fe{sub 15} powder were consolidated by vacuum hot pressing. • No changes in microstructure of Al{sub 65}Cu{sub 20}Fe{sub 15} powder in 20% and 40% composites. • Al{sub 2}Cu precipitates at the interfaces and inside the matrix in the 60% composite. • Increase of microhardness and compressive strength with content of reinforcement. • The friction coefficient were in the range 0.5–0.7. - Abstract: Aluminium matrix composites were consolidated from elemental Al powder and atomised Al{sub 65}Cu{sub 20}Fe{sub 15} particles by vacuum hot pressing technique. The spherical Al{sub 65}Cu{sub 20}Fe{sub 15} particles consisted of icosahedral quasicrystalline dendrites or cells and cubic τ-AlCu(Fe) phase located in interdendritic areas. The composites with different content of the reinforcement particles (20, 40 and 60 wt%) were prepared. All composites showed density about 99% and a good bonding between the Al{sub 65}Cu{sub 20}Fe{sub 15} particles and the matrix. It was shown that the phase composition of the atomised particles did not change after consolidation for the composite containing 20% and 40% added particles while Al{sub 2}Cu precipitates formed at the Al/Al{sub 65}Cu{sub 20}Fe{sub 15} interfaces and inside the matrix in the composite with 60% of Al{sub 65}Cu{sub 20}Fe{sub 15} particles. With the increase of the volume fraction of the reinforcement in the composite the hardness as well as compressive strength increased reaching the value of 173 HV{sub 0.5} and 370 MPa, respectively for 60% of Al{sub 65}Cu{sub 20}Fe{sub 15} particles. The friction coefficient slightly varied in the range 0.5–0.7 depending on the composition.

  14. HIGH TEMPERATURE EROSION WEAR OF CERMET PARTICLES REINFORCED SELF-FLUXING ALLOY MATRIX HVOF SPRAYED COATINGS

    Directory of Open Access Journals (Sweden)

    Andrei Surzhenkov

    2015-09-01

    Full Text Available In the present paper, the resistance of high velocity oxy-fuel (HVOF sprayed TiC-NiMo and Cr3C2-Ni cermet particles reinforced NiCrSiB self-fluxing alloy matrix coatings to high temperature erosion wear is studied. Microstructure of the coatings was examined by SEM, phase composition was determined by XRD. A four-channel centrifugal particle accelerator was applied to study the high temperature erosion wear of the coatings. The impact angles were 30 and 90 degrees, initial particle velocity was 50 m/s, temperature of the test - 650 degrees. Volume wear of the coatings was calculated and compared to the respective values of the reference materials. Wear mechanisms were studied by SEM.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7617

  15. Prediction of fracture characteristic of particle-reinforced alumina-based composites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Residual microstresses in particle reinforced alumina/SiC and alumina/mullite composites were calcu- lated. The results indicated that there existed a linear relation between matrix microstresses and the particle contents in the composites. The influence of stress state on crack propagating and grain boundary strengthening was analyzed. Ratios of grain boundary toughness to grain toughness of these composites were calculated in view of microstress analysis, and percentage of transgranular fracture (PTF) that increases with the microstress in the alumina matrix was then deduced. The relationship between microstructure, component, matrix microstresses, and PTF was established. Therefore, the fracture characteristic was predicted on basis of the particle content and distribution in addition to the microstructure of the composites.

  16. Development of microstructure in submicron particles reinforced magnesium matrix composite processed by room temperature deformation

    International Nuclear Information System (INIS)

    Magnesium matrix composite reinforced with submicron SiC particles was subjected to room temperature deformation. A stepped tensile method was adopted to observe the development of microstructure at different tensile strain state. The microstructure evolution determined by transmission electron microscopy showed that the existence of submicron SiC particles could promote dislocation multiplication as well as impede dislocation motion. Dislocation density around SiC particles increased with the increase of tensile strain. Compared with the matrix alloy, the composite could withstand greater external loads, which can be related to the pinning effect caused by the submicron SiC particles on the movement of grain and twin boundaries. The study of the interface between the submicron SiC particles and matrix in the composite suggested that single submicron SiC particle bonded well with the matrix alloy after tensile process. Initiation of micro-cracks usually generated in the submicron particle dense zone during tensile process, which could lead to the fracture of composite. - Highlights: • Interaction among SiCp, dislocations, grain boundaries and twinning is analyzed. • Microstructures of SiCp/AZ91 during tensile is characterized. • 0.2 μm SiCp has significant pinning effect on dislocation movement. • Interfacial bonding between 0.2 μm SiCp-Mg is analyzed

  17. Reinforced magnetic properties of Ni-doped BiFeO3 ceramic

    CERN Document Server

    Hwang, J S; Kang, J -H; Lee, K H; Lee, B W; Park, S Y; Lee, Y P

    2016-01-01

    Multiferroic materials attract considerable interest because of the wide range of potential applications such as spintronic devices, data storage and sensors. As a strong candidate for the applications among the limited list of single-phase multiferroic materials, BiFeO3 (BFO) is a quite attractive material due to its multiferroic properties at room temperature (RT). However, BFO is widely known to have large leakage current and small spontaneous polarization due to the existence of crystalline defects such as oxygen vacancies. Furthermore, the magnetic moment of pure BFO is very weak owing to its antiferromagnetic nature. In this paper, the effects of Ni2+ substitution on the magnetic properties of bulk BFO have been investigated. BFO, and BiFe0.99Ni0.01O3, BiFe0.98Ni0.02O3 and BiFe0.97Ni0.03O3 (BFNO: Ni-doped BFO) ceramics were prepared by solid-state reaction and rapid sintering, and analyzed by structural and magnetic-property measurements. The leakage current density was measured at RT by using a standar...

  18. Specimen Preparation for Metal Matrix Composites with a High Volume Fraction of Reinforcing Particles for EBSD Analysis

    Science.gov (United States)

    Smirnov, A. S.; Belozerov, G. A.; Smirnova, E. O.; Konovalov, A. V.; Shveikin, V. P.; Muizemnek, O. Yu.

    2016-07-01

    The paper deals with a procedure of preparing a specimen surface for the EBSD analysis of a metal matrix composite (MMC) with a high volume fraction of reinforcing particles. Unlike standard procedures of preparing a specimen surface for the EBSD analysis, the proposed procedure is iterative with consecutive application of mechanical and electrochemical polishing. This procedure significantly improves the results of an indexed MMC matrix in comparison with the standard procedure of specimen preparation. The procedure was verified on a MMC with pure aluminum (99.8% Al) as the matrix, SiC particles being used as reinforcing elements. The average size of the SiC particles is 14 μm, and their volume fraction amounts to 50% of the total volume of the composite. It has been experimentally found that, for making the EBSD analysis of a material matrix near reinforcing particles, the difference in height between the particles and the matrix should not exceed 2 µm.

  19. Investigation into the morphology, composition, structure and dry tribological behavior of rice husk ceramic particles

    Science.gov (United States)

    Hu, Enzhu; Hu, Kunhong; Xu, Zeyin; Hu, Xianguo; Dearn, Karl David; Xu, Yong; Xu, Yufu; Xu, Le

    2016-03-01

    To expand the application of rice husk (RH) resource, this study developed carbon-based RH ceramic (RHC) particles using a common high-temperature carbonization method. The morphology, composition, and structure of the RHC particles were characterized with a series of modern analysis technologies and were then compared with those of the initial RH powder and carbonized RH (CRH) particles. The dry tribological behavior of RHC particle adobes (RHAs) was also investigated. Results showed the sheet-shaped morphology of the RHC particles. The graphitization degree of the RHC particles was lower than that of the CRH particles possibly because the phenolic resin (PR) filled the micro-pores of the RH particles, thereby prompting the formation of amorphous carbon in the RHC particles as a result of high-temperature carbonization. The appearance of a hydroxy function group (sbnd OH) on the surface of the RHC particles was ascribed to the decomposition of PR at 900 °C. The friction coefficients and mass loss rates of the RHAs almost increased with the rise in load and velocity. In addition, the friction coefficients of the RHAs decreased at high load (5 N) and velocity (0.261 m/s) conditions. Such outcome indicated that the variation of contact area between steel ball and RHA at high load and velocity conditions resulted in the abrasive wear or catastrophic wear.

  20. Particle-Based Geometric and Mechanical Modelling of Woven Technical Textiles and Reinforcements for Composites

    Science.gov (United States)

    Samadi, Reza

    affecting the textile geometry and constitutive behaviour under evolving loading; 5) validating simulation results with experimental trials; and 6) demonstrating the applicability of the simulation procedure to textile reinforcements featuring large numbers of small fibres as used in PMCs. As a starting point, the effects of reinforcement configuration on the in-plane permeability of textile reinforcements, through-thickness thermal conductivity of PMCs and in-plane stiffness of unidirectional and bidirectional PMCs were quantified systematically and correlated with specific geometric parameters. Variability was quantified for each property at a constant fibre volume fraction. It was observed that variability differed strongly between properties; as such, the simulated behaviour can be related to variability levels seen in experimental measurements. The effects of the geometry of textile reinforcements on the aforementioned processing and performance properties of the textiles and PMCs made from these textiles was demonstrated and validated, but only for simple cases as thorough and credible geometric models were not available at the onset of this work. Outcomes of this work were published in a peer-reviewed journal [101]. Through this thesis it was demonstrated that predicting changes in textile geometry prior and during loading is feasible using the proposed particle-based modelling method. The particle-based modelling method relies on discrete mechanics and offers an alternative to more traditional methods based on continuum mechanics. Specifically it alleviates issues caused by large strains and management of intricate, evolving contact present in finite element simulations. The particle-based modelling method enables credible, intricate modelling of the geometry of textiles at the mesoscopic scale as well as faithful mechanical modelling under load. Changes to textile geometry and configuration due to the normal compaction pressure, stress relaxation, in-plane shear

  1. Particle Board and Oriented Strand Board Prepared with Nanocellulose-Reinforced Adhesive

    Directory of Open Access Journals (Sweden)

    Stefan Veigel

    2012-01-01

    Full Text Available Adhesives on the basis of urea-formaldehyde (UF and melamine-urea-formaldehyde (MUF are extensively used in the production of wood-based panels. In the present study, the attempt was made to improve the mechanical board properties by reinforcing these adhesives with cellulose nanofibers (CNFs. The latter were produced from dissolving grade beech pulp by a mechanical homogenization process. Adhesive mixtures with a CNF content of 0, 1, and 3 wt% based on solid resin were prepared by mixing an aqueous CNF suspension with UF and MUF adhesives. Laboratory-scale particle boards and oriented strand boards (OSBs were produced, and the mechanical and fracture mechanical properties were investigated. Particle boards prepared with UF containing 1 wt% CNF showed a reduced thickness swelling and better internal bond and bending strength than boards produced with pure UF. The reinforcing effect of CNF was even more obvious for OSB where a significant improvement of strength properties of 16% was found. For both, particle board and OSB, mode I fracture energy and fracture toughness were the parameters with the greatest improvement indicating that the adhesive bonds were markedly toughened by the CNF addition.

  2. Effect of electroless coating parameters and ceramic particle size on fabrication of a uniform Ni–P coating on SiC particles

    OpenAIRE

    Beigi Khosroshahi, N.; Azari Khosroshahi, R.; Taherzadeh Mousavian, R.; Brabazon, Dermot

    2014-01-01

    The formation of a uniform nickel phosphorous (Ni–P) electroless (EL) coating on micronsized SiC particles was investigated in this study. Metal coated ceramic particles could be used in applications including as the fabrication of cast metal matrix composites.Such ceramic particles have a better wettability in molten metal. In this work, the effects of EL coating parameters, SiC particle size and morphology on the coating uniformity and mechanical bonding at the SiC/Ni–P interface were studi...

  3. Mechanical characterisation of porous glass reinforced hydroxyapatite ceramics: Bonelike®

    Directory of Open Access Journals (Sweden)

    Silva Marcelo Henrique Prado da

    2003-01-01

    Full Text Available In the present study, mechanical properties of porous glass reinforced hydroxyapatite bioceramics were assessed by microhardness, bending and compression tests and fracture toughness determination. Porous discs were produced by a dry method using wax spheres as pore formers. Green bodies were sintered and the final microstructure of the composites consists of hydroxyapatite, alpha and beta tricalcium phosphate (alpha and b-Ca3(PO42due to the reaction between the glassy phase and the hydroxyapatite matrix. The results of the mechanical tests showed that the glassy phase yielded higher fracture toughness and bending strength when comparing with literature data for single hydroxyapatite. There is a compromise between mechanical properties and the porosity level for bioceramics: for example, according to Weibull statistics for composites with 65% porosity the maximum bending stress level is 0.2 MPa for 100% survival probability whereas this stress level increases to 2.5 MPa for composites with 40%. However, only the 65% porosity composite samples seem to have the complete adequate morphology for bone ingrowth.

  4. The high frequency fatigue behavior of continuous-fiber-reinforced ceramic matrix composites

    Science.gov (United States)

    Chawla, Nikhilesh

    Many potential applications for continuous fiber ceramic matrix composites (CFCMCs), such as gas turbines and heat exchangers, will involve high frequency cyclic loading (75 Hz or higher). While most of the work in the area of fatigue of CFCMCs has concentrated on low frequency behavior, it has been shown that fatigue at high frequencies can exacerbate the accumulation of microstructural damage and significantly decrease fatigue life. "Soft" matrix composites with strong interface bonding provided superior resistance to high frequency fatigue damage. Nicalon/SiCON composites with strong interfacial bonding between the fibers and matrix exhibited very little internal heating during high frequency fatigue loading. This composite system exhibited excellent fatigue life, with fatigue runout at 10sp7 cycles occurring for stresses close to 80% of the ultimate strength (at a loading frequency of 100 Hz). Thick fiber coatings may be more effective in reducing the amount of fiber wear and damage which occur during high frequency fatigue. More effective lubrication at the fiber/matrix interface was achieved with thicker carbon coatings in Nicalon/C/SiC composites subjected to high frequency fatigue loading. Composites with thicker coatings exhibited substantially lower frictional heating and had much higher fatigue lives. The effect of laminate stacking sequence had a significant effect on the high frequency fatigue behavior of CFCMCs. In SCS-6/Sisb3Nsb4 composites, frictional heating in angle-ply laminates (±45) was substantially higher than that in cross-ply laminates (0/90). Since the angle-ply had a lower stiffness, matrix microcracking in this composite was more predominant. Finally, preliminary fatigue damage mechanism maps for CFCMCs were developed. These maps provided a means to identify which fatigue mechanisms were operating at a given stress level and number of cycles.

  5. An Investigation of Laser Assisted Machining of Al_2O_3 Particle Reinforced Aluminum Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The Al 2O 3 particles reinforced aluminum matrix composite (Al 2O 3p/Al) are more and more widely used for their excellent physical and chemical properties. However, their poor machinability leads to severe tool wear and bad machined surface. In this paper laser assisted machining is adopted in machining Al 2O 3p/Al composite and good result was obtained. The result of experiment shows in machining Al 2O 3p/Al composites the cutting force is reduced in 30%~50%, the tool wear is reduced in 20%~30% an...

  6. Abrasive wear response of aluminium alloy-sillimanite particle reinforced composite under low stress condition

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M. [Regional Research Laboratory (CSIR), Hoshangabad Road, Near Habibganj Naka, Bhopal 462 026 (India)]. E-mail: mulayam_singh@hotmail.com; Mondal, D.P. [Regional Research Laboratory (CSIR), Hoshangabad Road, Near Habibganj Naka, Bhopal 462 026 (India); Das, S. [Regional Research Laboratory (CSIR), Hoshangabad Road, Near Habibganj Naka, Bhopal 462 026 (India)

    2006-03-15

    The abrasive wear behaviour of aluminium alloy-sillimanite particle reinforced composite under low stress condition has been reported and the results have been compared with the corresponding matrix alloy which was produced and cast under similar conditions. The study showed that wear resistance (inverse of wear rate) of the composite was higher than the matrix alloy. The wear rate decreased with sliding distance and increased with applied load irrespective of materials. The worn surfaces and subsurfaces of the tested samples were examined in the scanning electron microscope in order to understand the material removal mechanism during low stress abrasive wear process.

  7. X-ray microtomography of damage in particle-reinforced metal matrix composites

    International Nuclear Information System (INIS)

    The damage which occurs on plastic straining of silicon carbide particle-reinforced aluminium alloys has been characterised using x-ray microtomography. The technique is used to provide density measurements as a function of strain in addition to imaging the internal structure with a resolution of ∼15μm. This allows a much more accurate determination of microstructural damage in terms of void growth than is available from measurements of density using buoyancy methods or from elastic modulus decrease. These data can be combined with acoustic emission measurements during straining to allow damage nucleation and growth contributions to be separated. (orig.)

  8. Microstructure and wear properties of the electroslag remelting layer reinforced by TiC particles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The electroslag remelting (ESR) layer reinforced by TiC particles was obtained by electroslag remelting.The microstructure and wear properties of the ESR layer were studied by means of scanning electron microscopy (SEM),X-ray diffraction (XRD),and wear test.The results indicate that TiC particles are synthesized by self-propagating high-temperature synthesis (SHS) reaction during the electroslag remelting process.The size of TiC particles is in the range of 1-10 μm,and the distribution of TiC particles is uniform,from outside to inside of the ESR layer,and the volume fraction and the size of TiC particles decrease gradually.Molten iron and slag flow into porosity due to the SHS process leading to rapid densification and the elimination of porosity in the ESR layer during the ESR process.TiC particles enhance the wear resistance of the ESR layer,whereas CaF2 can improve the high temperature lubricating property of the ESR layer.

  9. Effects of Surface Treatments on the Bond Strength Between Resin Cement and a New Zirconia-reinforced Lithium Silicate Ceramic.

    Science.gov (United States)

    Sato, T P; Anami, L C; Melo, R M; Valandro, L F; Bottino, M A

    2016-01-01

    This study evaluated the effects of surface treatments on the bond strength between the new zirconia-reinforced lithium silicate ceramic (ZLS) and resin cement. VITA Suprinity blocks were crystallized according to the manufacturer's instructions and randomly assigned to six groups (N=36; n=6), according to the surface treatment to be performed and aging conditions: HF20, 10% hydrofluoric acid for 20 seconds, baseline (control); HF20tc, 10% hydrofluoric acid for 20 seconds, aging; HF40, 10% hydrofluoric acid for 40 seconds, baseline; HF40tc, 10% hydrofluoric acid for 40 seconds, aging; CJ, CoJet sandblasting (25 seconds, 2.5 bar, 15-mm distance), baseline; and CJtc, CoJet sandblasting (25 seconds, 2.5 bar, 15-mm distance), aging. All specimens were silanized (Monobond S) and cemented with Panavia F to newly polymerized Z250 resin blocks. After specimens were immersed for 24 hours in distilled water at 37° C, 1-mm(2) cross-section microbars were obtained by means of a cutting machine under constant cooling. Baseline groups were immediately tested, whereas "tc" groups were used to analyze the effect of aging on bond strength (10,000 thermal cycles, 5/55°C, 30-second bath). The microtensile bond strength test was performed with a universal testing machine (0.5 mm/min), and bond strength (MPa) was calculated when the load-to-failure (N) was divided by the adhesive area (mm(2)). We also evaluated the surface roughness (Sa, average roughness; Str, texture aspect ratio; Sdr, developed interfacial area ratio) and the contact angle resulting from the treatments. Data were statistically analyzed by one- or two-way analysis of variance and Tukey's test (all α=5%). The failure mode of each specimen was evaluated by stereomicroscopy, and representative specimens were analyzed by scanning electron microscopy. The microtensile bond strength was affected by the surface conditioning (p<0.0001), storage condition (p<0.0001), and the interaction between them (p=0.0012). The

  10. Exoemission of charged particles from the surface of irradiated high-temperature superconducting ceramics

    International Nuclear Information System (INIS)

    The present communication reports the results of the study of the samples of YBa2Cu3O7 ceramics with a density of 5.4 g/cm3, composed of one phase with Tc = 92 K in the form of 1 mm thick tablets 10 mm in diameter. Part of the samples was obtained in the air by the use of gamma-quanta (Cobalt-60), the absorbed dose was 106 rad. The design of the facility for recording the thermostimulated exoemission (TSE) spectra of positive and negative particles allowed the measurements to be made in the vacuum of 10-8 Tor at a heating rate of 0.1 K [4]. Part of the experiments was made using non-irradiated ceramics which were spalled in a vacuum chamber shortly before recording the TSE spectra

  11. Mutation particle swarm optimization of the BP-PID controller for piezoelectric ceramics

    Science.gov (United States)

    Zheng, Huaqing; Jiang, Minlan

    2016-01-01

    PID control is the most common used method in industrial control because its structure is simple and it is easy to implement. PID controller has good control effect, now it has been widely used. However, PID method has a few limitations. The overshoot of the PID controller is very big. The adjustment time is long. When the parameters of controlled plant are changing over time, the parameters of controller could hardly change automatically to adjust to changing environment. Thus, it can't meet the demand of control quality in the process of controlling piezoelectric ceramic. In order to effectively control the piezoelectric ceramic and improve the control accuracy, this paper replaced the learning algorithm of the BP with the mutation particle swarm optimization algorithm(MPSO) on the process of the parameters setting of BP-PID. That designed a better self-adaptive controller which is combing the BP neural network based on mutation particle swarm optimization with the conventional PID control theory. This combination is called the MPSO-BP-PID. In the mechanism of the MPSO, the mutation operation is carried out with the fitness variance and the global best fitness value as the standard. That can overcome the precocious of the PSO and strengthen its global search ability. As a result, the MPSO-BP-PID can complete controlling the controlled plant with higher speed and accuracy. Therefore, the MPSO-BP-PID is applied to the piezoelectric ceramic. It can effectively overcome the hysteresis, nonlinearity of the piezoelectric ceramic. In the experiment, compared with BP-PID and PSO-BP-PID, it proved that MPSO is effective and the MPSO-BP-PID has stronger adaptability and robustness.

  12. Residual stress analysis in carbon fiber-reinforced SiC ceramics; Eigenspannungsanalyse in kohlenstoffaserverstaerkten SiC-Keramiken

    Energy Technology Data Exchange (ETDEWEB)

    Broda, M.

    1998-12-31

    Systematic residual stress analyses are reported, carried out in long-fiber reinforced SiC ceramics. The laminated C{sub fiber}/SiC{sub matrix} specimens used were prepared by polymer pyrolysis, and the structural component specimens used are industrial products. Various diffraction methods have been applied for non-destructive evaluation of residual stress fields, so as to completely detect the residual stresses and their distribution in the specimens. The residual stress fields at the surface ({mu}m) have been measured using characteristic X-radiation and applying the sin {sup 2}{psi} method as well as the scatter vector method. For residual stress field analysis in the mass volume (cm), neutron diffraction has been applied. The stress fields in the fiber layers (approx. 250{mu}m) have been measured as a function of their location within the laminated composite by using an energy-dispersive method and synchrotron radiation. By means of the systematic, process-accompanying residual stress and phase analyses, conclusions can be drawn as to possible approaches for optimization of fabrication parameters. (orig./CB) [Deutsch] Im Rahmen der Arbeit werden systematische Eigenspannungsanalysen an langfaserverstaerkten SiC-Keramiken durchgefuehrt. Hierbei werden polymerpyrolytisch abgeleitete, laminierte C{sub Faser}/SiC{sub Matrix} Proben und Bauteile untersucht, welche industriell gefertigt wurden. Fuer die zerstoerungsfreie Eigenspannungsermittlung kommen verschiedene Beugungsverfahren zum Einsatz. Dadurch kann die Eigenspannungsverteilung in diesen Proben vollstaendig erfasst werden, d.h. der Eigenspannungszustand im Oberflaechenbereich ({mu}m) wird mit Hilfe charakteristischer Roentgenstrahlung unter Nutzung der sin{sup 2}{psi}-Methode als auch der Streuvektor-Methode beschrieben. Fuer die Analyse der Eigenspannungen im Volumen (cm) wird die Neutronenbeugung herangezogen. Um den Spannungszustand in den einzelnen Fasermatten (ca. 250 {mu}m) in Abhaengigkeit ihrer Lage

  13. In-flight behavior of dissimilar co-injected particles in the spraying of metal-ceramic functionally gradient materials

    Energy Technology Data Exchange (ETDEWEB)

    Fincke, J.R.; Swank, W.D.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1997-12-31

    In the spraying of functionally gradient coatings the particle ensemble delivered to the substrate can vary from a relatively low melting point metallic particle to a significantly higher melting point ceramic particle. At various stages in the spray process the particle ensemble can be either predominantly metallic, ceramic, or an intermediate combination. For co-injected particles the mixtures do not behave as a simple linear superposition of the spray patterns of the individual particle types. The particle temperature, velocity, size distributions, and pattern characteristics of the resulting spray fields is examined for all ceramic particle sprays (ZrO{sub 2}), all metallic particle sprays (NiCrAlY), and for a 1:1 mixture. The major particle-particle interaction occurs in the injector itself and results in a modified spray pattern which is different from that of either material sprayed alone. The particle velocity distributions generally exhibit a bimodal nature which is dependent on the size and density of the injected particles.

  14. Effect of ageing on the mechanical behaviour of aluminium alloy AA2009 reinforced with SIC particles

    International Nuclear Information System (INIS)

    A study of the mechanical behaviour of an aluminium matrix composite (AA2009) reinforced with 15 volume percent of SiC particles has been carried out. The ageing kinetic for this material has been evaluated at two different ageing temperatures (170 and 190 degree centigrade). The hardness peaks for the two different precipitation sequences existing in the matrix alloy have been identified. The mechanical behaviour of the composite was also evaluated for the different thermal conditions (as-received and aged). This research has been completed with the identification of the fracture mechanisms by means of observation with scanning electron microscopy (SEM) both of the fracture surface and transversal sections of them. In addition, transmission electron microscopy (TEM) of the treated composites has been used to determine the influence of the SiC particles on the distribution of strengthening phases precipitated in the matrix. (Author) 14 refs

  15. Solid Particle Erosion of Date Palm Leaf Fiber Reinforced Polyvinyl Alcohol Composites

    Directory of Open Access Journals (Sweden)

    Jyoti R. Mohanty

    2014-01-01

    Full Text Available Solid particle erosion behavior of short date palm leaf (DPL fiber reinforced polyvinyl alcohol (PVA composite has been studied using silica sand particles (200 ± 50 μm as an erodent at different impingement angles (15–90° and impact velocities (48–109 m/s. The influence of fiber content (wt% of DPL fiber on erosion rate of PVA/DPL composite has also been investigated. The neat PVA shows maximum erosion rate at 30° impingement angle whereas PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semiductile behavior. The erosion efficiency of PVA and its composites varies from 0.735 to 16.289% for different impact velocities studied. The eroded surfaces were observed under scanning electron microscope (SEM to understand the erosion mechanism.

  16. Modification of Magnesium Alloys by Ceramic Particles in Gravity Die Casting

    Directory of Open Access Journals (Sweden)

    Urs Haßlinger

    2014-01-01

    Full Text Available A critical drawback for the application of magnesium wrought alloys is the limited formability of semifinished products that arises from a strong texture formation during thermomechanical treatment. The ability of second phase particles embedded into the metal matrix to alter this texture evolution is of great interest. Therefore, the fabrication of particle modified magnesium alloys (particle content 0.5–1 wt.-% by gravity die casting has been studied. Five different types of micron sized ceramic powders (AlN, MgB2, MgO, SiC, and ZrB2 have been investigated to identify applicable particles for the modification. Agglomeration of the particles is revealed to be the central problem for the fabrication process. The main factors that influence the agglomerate size are the particle size and the intensity of melt stirring. Concerning handling, chemical stability in the Mg-Al-Zn alloy system, settling and wetting in the melt, and formation of the microstructure in most cases, the investigated powders show satisfying properties. However, SiC is chemically unstable in aluminum containing alloys. The high density of ZrB2 causes large particles to settle subsequent to stirring resulting in an inhomogeneous distribution of the particles over the cast billet.

  17. In situ fabrication and microstructure of Al2O3 particles reinforced aluminum matrix composites

    International Nuclear Information System (INIS)

    Al2O3p/Al composites were prepared by direct melt reaction process. The thermodynamics of in situ chemical reactions between molten aluminum and CeO2 powder was studied. The XRD results show that the components of the as-prepared composites consist of Al2O3 and Al phases. For the as-cast composite specimens, SEM, EDX, TEM and SAD were used to analyze the reinforcement phases and interface characters of composites. The results show that the in situ generated Al2O3 particles, whose sizes are 100-200 nm, have various irregular shapes and disperse uniformly in matrix. TEM observation shows that the interface between particle and matrix is clean. Furthermore, there is no fixed orientation relationship between Al2O3 particles and aluminum matrix. Only [12-bar 10]//[111] orientation parallel relationship with low exponent is found. Therefore, the composites have isotropic properties. Besides characters mentioned above, there are large amount of high density dislocations and the generated extensive fine subgrains around Al2O3 particles. These features are favorable for improving composite performances. As a result, the composites are comprehensively strengthened not only by Al2O3 particles, but also by the high density dislocations and fine subgrains.

  18. Aluminium EN AW-2124 alloy matrix composites reinforced with Ti(C,N), BN and Al2O3 particles

    International Nuclear Information System (INIS)

    Investigation results of the aluminium alloy EN AW-2124 matrix composite materials with particles of the powders Ti(C,N), BN and Al2O3 (15 wt.%) are presented in the paper. In order to obtain uniform distribution of reinforcement particles in aluminium alloy matrix powders of composite components have been milled in the rotary ball-bearing pulverizer. The composites have been pressed in laboratory vertical press at room temperature under the pressure of 500 kN. Obtained die samplings have been heated to the temperature 520-550 oC and extruded. Bars of diameter 8 mm have been received as a final product. Metallographic examination of the composites materials' structure shows non-uniform distribution of reinforced powders in the aluminium alloy matrix banding of reinforcements particles corresponds to the extrusion direction. Particles of reinforcement distribution in aluminium alloy matrix is irregular, some agglomerations of powder of aluminium oxide and porosity of different size have been noticed. Investigations of hardness and ultimate compressive strength show that the particles of reinforcement improve mechanical properties of composite materials. Investigations of compressive strength, carried out at room temperature, enable to compare mechanical properties of matrix and composite. (author)

  19. Enhancement of Compatibility between Ultrahigh-Molecular-Weight Polyethylene Particles and Butadiene.Nitrile Rubber Matrix with Nanoscale Ceramic Particles and Characterization of Evolving Layer

    Energy Technology Data Exchange (ETDEWEB)

    Shadrinov, Nikolay V.; Sokolova, Marina D.; Cho, Jinho [Institute of Oil and Gas Issues, Yakutsk (Russian Federation); Okhlopkova, A. A. [North-Eastern Federal Univ., Yakutsk (Russian Federation); Lee, Jungkeun; Jeong, Daeyong [Myongji Univ., Seoul (Korea, Republic of)

    2013-12-15

    This article examines the modification of surface properties of ultrahigh-molecular-weight polyethylene (UHMWPE) with nanoscale ceramic particles to fabricate an improved composite with butadiene.nitrile rubber (BNR). Adhesion force data showed that ceramic zeolite particles on the surface of UHMWPE modulated the surface state of the polymer and increased its compatibility with BNR. Atomic force microscopy phase images showed that UHMWPE made up the microphase around the zeolite particles and formed the evolving layer with a complex interface. The complex interface resulted in improvements in the mechanical properties of the composite, especially its low-temperature resistance coefficients, thereby improving its performance in low-temperature applications.

  20. Solid ceramic SiCO microspheres and porous rigid siloxane microspheres from swellable polysiloxane particles

    Energy Technology Data Exchange (ETDEWEB)

    Fortuniak, Witold [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland); Chojnowski, Julian, E-mail: jchojnow@cbmm.lodz.pl [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland); Slomkowski, Stanislaw [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland); Nyczyk-Malinowska, Anna [Faculty of Materials Science and Ceramics, AGH-University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Pospiech, Piotr; Mizerska, Urszula [Center of Molecular and Macromolecular Studies, Polish Academy of Science, 112 Sienkiewicza, 90-363 Łódź (Poland)

    2015-04-01

    Solid silicon oxycarbide (SiCO) ceramic microspheres and rigid porous siloxane microspheres were obtained in a two step process. First, polysiloxane microspheres with a large number of Si–OH groups in their bulk and on their surface were synthesized from polyhydromethylsiloxane (PHMS) using a recently developed process. The process included a combination of three reactions of Si–H groups of PHMS occurring in aqueous emulsion and catalyzed by the same Karstedt Pt(0) complex: (i) hydrosilylation of 1,3-divinyltetramethyldisiloxane (DVTMDS), (ii) hydrolysis, (iii) dehydrogenocondensation involving the SiOH groups formed during the hydrolysis. DVTMDS was grafted on PHMS prior to emulsification. Microspheres had a loose structure and were able to absorb a significant amount of organic solvents. In the second step the microspheres were subjected to pyrolysis with heating in the argon atmosphere at following temperatures: 400, 700 and 1000 °C. These heated at 400 °C had micro and mezopores, while those heated at 700 and 1000 °C gave spherical solid SiCO ceramic particles. Polysiloxane microspheres and microspheres obtained by pyrolysis of the former were analyzed by {sup 29}Si and {sup 13}C MAS NMR, FTIR, SEM, and N{sub 2} gas adsorption. - Highlights: • Thermal properties of cross-linked polysiloxane microspheres are studied. • New route to solid silicon oxycarbide microspheres is worked out. • New method of preparation of mezoporous siloxane microspheres is shown. • Role of silanol side groups on polysiloxane in its ceramization is explained.

  1. Solid ceramic SiCO microspheres and porous rigid siloxane microspheres from swellable polysiloxane particles

    International Nuclear Information System (INIS)

    Solid silicon oxycarbide (SiCO) ceramic microspheres and rigid porous siloxane microspheres were obtained in a two step process. First, polysiloxane microspheres with a large number of Si–OH groups in their bulk and on their surface were synthesized from polyhydromethylsiloxane (PHMS) using a recently developed process. The process included a combination of three reactions of Si–H groups of PHMS occurring in aqueous emulsion and catalyzed by the same Karstedt Pt(0) complex: (i) hydrosilylation of 1,3-divinyltetramethyldisiloxane (DVTMDS), (ii) hydrolysis, (iii) dehydrogenocondensation involving the SiOH groups formed during the hydrolysis. DVTMDS was grafted on PHMS prior to emulsification. Microspheres had a loose structure and were able to absorb a significant amount of organic solvents. In the second step the microspheres were subjected to pyrolysis with heating in the argon atmosphere at following temperatures: 400, 700 and 1000 °C. These heated at 400 °C had micro and mezopores, while those heated at 700 and 1000 °C gave spherical solid SiCO ceramic particles. Polysiloxane microspheres and microspheres obtained by pyrolysis of the former were analyzed by 29Si and 13C MAS NMR, FTIR, SEM, and N2 gas adsorption. - Highlights: • Thermal properties of cross-linked polysiloxane microspheres are studied. • New route to solid silicon oxycarbide microspheres is worked out. • New method of preparation of mezoporous siloxane microspheres is shown. • Role of silanol side groups on polysiloxane in its ceramization is explained

  2. Compression Creep Behavior of High Volume Fraction of SiC Particles Reinforced Al Composite Fabricated by Pressureless Infiltration

    Institute of Scientific and Technical Information of China (English)

    XU Fu-min; WU Lawrence Chi-man; HAN Guang-wei; TAN Yi

    2007-01-01

    The compression creep deformation of the high volume fraction of SiC particles reinforced Al-Mg-Si composite fabricated by pressure-less infiltration was investigated. The experimental results show that the creep stress exponents are very high at temperatures of 673 K, 723 K and 773 K, and if taking the threshold stress into account, the true stress exponent of minimum creep strain rate is still approximately 5, although the volume fraction of reinforcements is very high. The creep strain rate in the high volume fraction reinforced aluminum alloy matrix composites is controlled by matrix lattice diffusion. It is found that the creep-strengthening effect of high volume fraction of silicon carbide particles is significant, although the particles do not form effective obstacles to dislocation motion.

  3. Recovery and Modification of Waste Tire Particles and Their Use as Reinforcements of Concrete

    Directory of Open Access Journals (Sweden)

    Eduardo Sadot Herrera-Sosa

    2015-01-01

    Full Text Available Environmental pollution caused by solid wastes is increasing in the last decades; one of these is referred to automotive tires, which are recycled by different methods, including mechanical grinding. One of the most recurrent applications is to use recycled particles as fillers in building materials, as hydraulic concrete. Nevertheless, detrimental values on the mechanical properties are obtained when they are added. For solving these problems, in this work, a novel proposal is to modify the physicochemical properties of the waste automotive tire particles, previously obtained by grinding process, by using gamma irradiation in order to use them as reinforcements of hydraulic concrete. The results show that improvements on the mechanical properties depend of gamma irradiation as well as concentration and size of waste tire particles. Moreover, SEM images are related to mechanical properties; for instance, rough surface of the tire particles changes when applying irradiation; more smooth surfaces are created, due to the cross-linking of polymer chains. Nevertheless, for higher doses, cracks are observed which are produced by scission of the polymer chains.

  4. Computer Simulation of the Indentation Creep Tests on Particle-Reinforced Composites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A systematical simulation has been carried out on the indentation creep test on particle-reinforced composites. The deformation, failure mechanisms and life are analyzed by three reasonable models. The following five factors have been considered simultaneously: creep property of the particle, creep property of the matrix, the shape of the particle,the volume fraction of the particle and the size (relative size to the particle) of the indentation indenter. For all the cases, the power law respecting to the applied stress can be used to model the steady indentation creep depth rate of the indenter, and the detail expressions have been presented. The computer simulation precision is analyzed by the two-phase model and the three-phase model. Two places of the stress concentration are found in the composites.One is ahead of the indentation indenter, where the high stress state is deduced by the edge of the indenter and will decrease rapidly near to a steady value with the creep time. The other one is at the interface, where the high stress state is deduced by the misfit of material properties between the particles and matrix. It has been found that the creep dissipation energy density other than a stress parameter can be used to be the criterion to model the debonding of the interfaces. With the criterion of the critical creep dissipation energy density, a power law to the applied stress with negative exponent can be used to model the failure life deduced by the debonding of interfaces. The influences of the shape of the particles and the matching of creep properties of particle and matrix can be discussed for the failure. With a crack model, the further growth of interface crack is analyzed, and some important experimental phenomena can be predicted. The failure mechanism which the particle will be punched into matrix has been also discussed. The critical diflerences between the creep properties of the particles and matrix have been calculated,after a parameter has

  5. Ceramic Technology Project database: September 1990 summary report. [SiC, SiN, whisker-reinforced SiN, ZrO-toughened aluminas, zirconias, joints

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, B.L.P.

    1992-06-01

    Data generated within the Ceramic Technology Project (CTP) represent a valuable resource for both research and industry. The CTP database was created to provide easy access to this information in electronic and hardcopy forms by using a computerized database and by issuing periodic hardcopy reports on the database contents. This report is the sixth in a series of semiannual database summaries and covers recent additions to the database, including joined brazed specimen test data. It covers 1 SiC, 34 SiN, 10 whisker-reinforced SiN, 2 zirconia-toughened aluminas, 8 zirconias, and 34 joints.

  6. Preparation, microstructural evolution and properties of Ni–Zr intermetallic/Zr–Si ceramic reinforced composite coatings on zirconium alloy by laser cladding

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Kun; Li, Yajiang, E-mail: yajli@sdu.edu.cn; Wang, Juan; Ma, Qunshuang; Li, Jishuai; Li, Xinyue

    2015-10-25

    NiZr{sub 2}–ZrSi–Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4}-ZrC intermetallic/ceramic reinforced composite coatings were in situ synthesized by laser cladding the pre-placed Ni–Cr–B–Si powder on zirconium substrate. Microstructure and phase constituents were investigated by X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Microhardness tester and block-on-ring wear tester were employed to measure the hardness distribution and wear resistance of the intermetallic/ceramic reinforced composite coating. Results indicated that the multiphase of reinforcements includes Ni–Zr intermetallic compounds (e.g., NiZr and NiZr{sub 2}) and Zr–Si(C) ceramic phases (e.g., ZiSi, Zr{sub 5}Si{sub 4} and ZrC). Ni–Si clusters transforming to Zr–Si–Ni clusters at high temperature facilitated the forming of Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4} and during the growth of Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4}, the consumption of Zr atoms at the lateral interface of liquid/Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4} resulted into developing Zr-poor zone near Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4}. The microhardness and wear resistance of the coating were significantly improved by various reinforced phases in comparison to zirconium substrate. - Highlights: • NiZr{sub 2}–ZrSi–Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4}-ZrC compostie coating was in-situ synthesized. • Ni–Si clusters transforming resulted into developing Zr-poor zone near Zr{sub 5}(Si{sub x}Ni{sub 1−x}){sub 4}. • Reinforced phases significantly improve wear resistance of the coating.

  7. Strength properties and fracture behavior of ZrC particle-reinforced tungsten composite

    Institute of Scientific and Technical Information of China (English)

    王玉金; 宋桂明; 孟庆昌; 周玉

    2001-01-01

    The flexural strength of 30 % (volume fraction) ZrC particle-reinforced tungsten composite (ZrCp/W) at 20~1 200℃ were measured using three-point bending, and the fracture behaviors of the samples at 20 ℃ and 1000 ℃ were studied with a scanning electron microscope. As temperature increases, the strength of the composite increases firstly and the highest strength value, 829 MPa, is measured at 1 000 ℃, and then the strength decreases when temperature is over 1000 ℃. The fracture of the composite at 20 ℃, which is controlled by the crack initiating process, is brittle, and the corresponding stress-deflection curve is linear. There is a metastable growth and coalescence of the initial cracks during the fracture process of the samples at 1 000 ℃, and the stress-deflection curve displays a nonlinear characteristic. The good elevated strength of the composite is partly attributed to the W grain interior strength and ZrCp/W interface strength. The reinforcement at high temperature is mainly attributed to the load transfer of ZrCp/W interface and dislocation strengthening.

  8. Ceramic based lightweight composites with extreme dynamic strength

    International Nuclear Information System (INIS)

    On the basis of several years experiments in development of high performance technical ceramics and in investigation of hetero-modulus and hetero-viscous materials and ceramic matrix composites the authors successfully developed a new family of ceramic reinforced lightweight composites with extreme dynamic strength. To obtain these lightweight composites first the matrix materials were developed from different sort of sintered ceramics with high porosity and after the prepared items were re-sintered using reactive sintering methods or were impregnated with nanoparticles of Si3N4, SiAlON ceramics or light metal alloys having excellent mechanical strength and properties. Where it was necessary the pores and material structures of ceramic matrix materials anchored excellent wetting for a wide range of metal alloys, so it was possible to develop several types of ceramic reinforced hetero-modulus light metal composites with extreme dynamic strength of different density. In this work the authors present the c-Si3N4 diamond particles reinforced corundum matrix composite shield plate structures and some of the specially developed low density ceramic foams and high porosity ceramic matrix materials for lightweight metallic composites

  9. Localized dispersing of ceramic particles in tool steel surfaces by pulsed laser radiation

    Science.gov (United States)

    Hilgenberg, K.; Behler, K.; Steinhoff, K.

    2014-06-01

    In this paper the capability of a localized laser dispersing technique for changing the material microstructure and the surface topology of steels is discussed. The laser implantation named technique bases on a discontinuous dispersing of ceramic particles into the surface of steels by using pulsed laser radiation. As ceramic particles TiC, WC and TiB2 are used, substrate material is high-alloyed cold working steel (X153CrMoV12). The influence of the laser parameters pulse length and pulse intensity was investigated in a comprehensive parameter study. The gained surface topology and microstructure were evaluated by optical microscopy, energy dispersive X-ray spectroscopy (EDX) and white light interferometry; mechanical properties were analyzed by micro hardness measurement. The experiments reveal that the alignment of separated, elevated, dome-shaped spots on the steel surface is feasible. The geometrical properties as well as the mechanical properties are highly controllable by the laser parameters. The laser implanted spots show a mostly crack-free and pore-free bonding to the substrate material as well as a significant increase of micro hardness.

  10. Localized dispersing of ceramic particles in tool steel surfaces by pulsed laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Hilgenberg, K., E-mail: hilgenberg@uni-kassel.de [Metal Forming Technology, University of Kassel (Germany); Behler, K. [Laser Technology, THM University of Applied Sciences (Germany); Steinhoff, K. [Metal Forming Technology, University of Kassel (Germany)

    2014-06-01

    In this paper the capability of a localized laser dispersing technique for changing the material microstructure and the surface topology of steels is discussed. The laser implantation named technique bases on a discontinuous dispersing of ceramic particles into the surface of steels by using pulsed laser radiation. As ceramic particles TiC, WC and TiB{sub 2} are used, substrate material is high-alloyed cold working steel (X153CrMoV12). The influence of the laser parameters pulse length and pulse intensity was investigated in a comprehensive parameter study. The gained surface topology and microstructure were evaluated by optical microscopy, energy dispersive X-ray spectroscopy (EDX) and white light interferometry; mechanical properties were analyzed by micro hardness measurement. The experiments reveal that the alignment of separated, elevated, dome-shaped spots on the steel surface is feasible. The geometrical properties as well as the mechanical properties are highly controllable by the laser parameters. The laser implanted spots show a mostly crack-free and pore-free bonding to the substrate material as well as a significant increase of micro hardness.

  11. Localized dispersing of ceramic particles in tool steel surfaces by pulsed laser radiation

    International Nuclear Information System (INIS)

    In this paper the capability of a localized laser dispersing technique for changing the material microstructure and the surface topology of steels is discussed. The laser implantation named technique bases on a discontinuous dispersing of ceramic particles into the surface of steels by using pulsed laser radiation. As ceramic particles TiC, WC and TiB2 are used, substrate material is high-alloyed cold working steel (X153CrMoV12). The influence of the laser parameters pulse length and pulse intensity was investigated in a comprehensive parameter study. The gained surface topology and microstructure were evaluated by optical microscopy, energy dispersive X-ray spectroscopy (EDX) and white light interferometry; mechanical properties were analyzed by micro hardness measurement. The experiments reveal that the alignment of separated, elevated, dome-shaped spots on the steel surface is feasible. The geometrical properties as well as the mechanical properties are highly controllable by the laser parameters. The laser implanted spots show a mostly crack-free and pore-free bonding to the substrate material as well as a significant increase of micro hardness.

  12. Wear Resistance of Aluminum Matrix Composites Reinforced with Al2O3 Particles After Multiple Remelting

    Science.gov (United States)

    Klasik, Adam; Pietrzak, Krystyna; Makowska, Katarzyna; Sobczak, Jerzy; Rudnik, Dariusz; Wojciechowski, Andrzej

    2016-01-01

    Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al2O3 particles were submitted to multiple remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple remelting method must be analyzed for any material separately.

  13. Weibull Probability Model for Fracture Strength of Aluminium (1101)-Alumina Particle Reinforced Metal Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    A.Suresh Babu; V.Jayabalan

    2009-01-01

    In recent times, conventional materials are replaced by metal matrix composites (MMCs) due to their high specific strength and modulus.Strength reliability, one of the key factors restricting wider use of composite materials in various applications, is commonly characterized by Weibull strength distribution function.In the present work, statistical analysis of the strength data of 15% volume alumina particle (mean size 15 μm)reinforced in aluminum alloy (1101 grade alloy) fabricated by stir casting method was carried out using Weibull probability model.Twelve tension tests were performed according to ASTM B577 standards and the test data, the corresponding Weibull distribution was obtained.Finally the reliability of the composite behavior in terms of its fracture strength was presented to ensure the reliability of composites for suitable applications.An important implication of the present study is that the Weibull distribution describes the experimentally measured strength data more appropriately.

  14. Mechanical resistance of the alumina reinforced by Si C nanometric particles

    International Nuclear Information System (INIS)

    The strength behavior of nano sized Si C particles reinforced alumina was investigated. Hot techniques, namely, mechanical mixture of powders and chemical precipitation of the alumina matrix or of the Si C phase, was used to prepare fully dense materials. The results obtained, characterised by SEM and TEM, showed that the microstructure obtained presented great differences in the microstructure, different Al2 O3 matrix. Despite these differences in the microstructure, no distinctive variation in the flexure strength was observed. This indicated that the critical flaw presented in all materials was the same and was probably related with surfaces defects, originated from the machining, rather than from the microstructure. The improvement in the flexure strength over the unreinforced Al2 O3 was small (around 10%). (author)

  15. Assessment of microcapsule—catalyst particles healing system in high performance fibre reinforced polymer composite

    Science.gov (United States)

    Bolimowski, P. A.; Wass, D. F.; Bond, I. P.

    2016-08-01

    Autonomous self-healing in carbon fibre reinforced polymer (CFRP) is demonstrated using epoxy resin filled microcapsules and a solid-state catalyst. Microcapsules filled with oligomeric epoxy resin (20–450 μm) and particles of Sc(OTf)3 are embedded in an interleave region of a unidirectional CFRP laminate and tested under mode I loading. Double cantilever beam (DCB) test specimens containing variable concentrations of microcapsules and catalyst were prepared, tested and compared to those healed by manual injection with corresponding healing resin formulation. The healing efficiency was evaluated by comparing the maximum peak load recorded on load–displacement curves for pristine and healed specimens. A 44% maximum recovery was observed for specimens containing 10 wt% of solid phase catalyst and 11 wt% of epoxy microcapsules. However, a significant (80%) decrease in initial strain energy release rate (G IC) was observed for specimens with the embedded healing chemistries.

  16. Mechanical properties study of particles reinforced aluminum matrix composites by micro-indentation experiments

    Directory of Open Access Journals (Sweden)

    Yuan Zhanwei

    2014-04-01

    Full Text Available By using instrumental micro-indentation technique, the microhardness and Young’s modulus of SiC particles reinforced aluminum matrix composites were investigated with micro-compression-tester (MCT. The micro-indentation experiments were performed with different maximum loads, and with three loading speeds of 2.231, 4.462 and 19.368 mN/s respectively. During the investigation, matrix, particle and interface were tested by micro-indentation experiments. The results exhibit that the variations of Young’s modulus and microhardness at particle, matrix and interface were highly dependent on the loading conditions (maximum load and loading speed and the locations of indentation. Micro-indentation hardness experiments of matrix show the indentation size effects, i.e. the indentation hardness decreased with the indentation depth increasing. During the analysis, the effect of loading conditions on Young’s modulus and microhardness were explained. Besides, the elastic–plastic properties of matrix were analyzed. The validity of calculated results was identified by finite element simulation. And the simulation results had been preliminarily analyzed from statistical aspect.

  17. Microstructure and mechanical properties of aluminum alloy matrix composite reinforced with nano-particle MgO

    Energy Technology Data Exchange (ETDEWEB)

    Yar, A. Ansary, E-mail: arash_ansaryyar@yahoo.co [Department of Materials, Islamic Azad University, South Tehran Branch, P.O. Box 11365-4435, Tehran (Iran, Islamic Republic of); Montazerian, M.; Abdizadeh, H. [School of Metallurgy and Materials Engineering, University of Tehran, P.O. Box 11365-4563, Tehran (Iran, Islamic Republic of); Baharvandi, H.R. [Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran (Iran, Islamic Republic of)

    2009-09-18

    In this research, aluminum alloy (A356.1) matrix composites reinforced with 1.5, 2.5 and 5 vol% nano-particle MgO were fabricated via stir casting method. Fabrication was performed at various casting temperatures, viz. 800, 850 and 950 deg. C. Optimum amount of reinforcement and casting temperature were determined by evaluating the density, microstructure and mechanical properties of composites. The composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Hardness and compression tests were carried out in order to identify mechanical properties. The results reveal that the composites containing 1.5 vol% reinforcement particle fabricated at 850 deg. C have homogenous microstructure as well as improved mechanical properties.

  18. ThermophysicalProperties of Cellular Aluminium andCeramic Particulate / Aluminium Composites

    Directory of Open Access Journals (Sweden)

    Khalid Almadhoni

    2015-10-01

    Full Text Available In this paper, the thermophysical properties of cellular Al and Ceramic Particulate / Al Composites were explored. Thermophysical properties are defined as material properties that vary with temperature without altering the material's chemical identity including thermal conductivity (TC, coefficient of thermal expansion (CTE, energy absorption, porosity and relative density. The significance of cellular Al and AMMCs reinforced by ceramic particles lies in their propertieswhich are difficult to be available combined in other engineering materials. New cellular AMMCs that meet the needs of the required engineering applications could be synthesized by selection an appropriate reinforcements. Different kinds of ceramic particles such as oxides, carbides, nitrides, as well as carbon nanotubes can be utilized as reinforcements for manufacturing of cellular AMMCs. Thermophysicalproperties of cellular AMMCs consisting of Al as continuous matrix phase and ceramic particles as reinforcements are directly influenced by type, size, and geometry of dispersions, also the RVR. In addition, the constituents of ceramic particulate / aluminium composites characterized by different heat transfer mechanisms, wherethe TC mechanism in metals is attributed to free electrons, while phonons are primarily responsible for TC in nonmetallic materials, as well as an interfacial thermal barrier resistance influence effectively on heat transfer inside the composite and thus the thermophysical properties. In this paper, based on the literature review, thermophysical properties of cellular Al and AMMCs reinforced by ceramic particles were discussed.

  19. Characteristics and fabrication of cermet spent nuclear fuel casks: ceramic particles embedded in steel

    International Nuclear Information System (INIS)

    Cermets are being investigated as an advanced material of construction for casks that can be used for storage, transport, or disposal of spent nuclear fuel (SNF). Cermets, which consist of ceramic particles embedded in steel, are a method to incorporate brittle ceramics with highly desirable properties into a strong ductile metal matrix with a high thermal conductivity, thus combining the best properties of both materials. Traditional applications of cermets include tank armor, vault armor, drill bits, and nuclear test-reactor fuel. Cermets with different ceramics (DUO2, Al2O3, Gd2O3, etc.) are being investigated for the manufacture of SNF casks. Cermet casks offer four potential benefits: greater capacity (more SNF assemblies) for the same gross weight cask, greater capacity (more SNF assemblies) for the same external dimensions, improved resistance to assault, and superior repository performance. These benefits are achieved by varying the composition, volume fraction, and particulate size of the ceramic particles in the cermet with position in the cask body. Addition of depleted uranium dioxide (DUO2) to the cermet increases shielding density, improves shielding effectiveness, and increases cask capacity for a given cask weight or size. Addition of low-density aluminium oxide (Al2O3) to the outer top and bottom sections of the cermet cask, where the radiation levels are lower, can lower cask weight without compromising shielding. The use of Al2O3 and other oxides, in appropriate locations, can increase resistance to assault. Repository performance may be improved by compositional control of the cask body to (1) create a local geochemical environment that slows the long-term degradation of the SNF and (2) enables the use of DUO2 for longterm criticality control. While the benefits of using cermets follow directly from their known properties, the primary challenge is to develop low-cost methods to fabricate casks with variable cermet compositions as a function of

  20. Characteristics and fabrication of cermet spent nuclear fuel casks: ceramic particles embedded in steel

    Energy Technology Data Exchange (ETDEWEB)

    Forsberg, C.W.; Swaney, P.M.; Tiegs, T.N. [Oak Ridge National Lab., Oak Ridge, TN (United States)

    2004-07-01

    Cermets are being investigated as an advanced material of construction for casks that can be used for storage, transport, or disposal of spent nuclear fuel (SNF). Cermets, which consist of ceramic particles embedded in steel, are a method to incorporate brittle ceramics with highly desirable properties into a strong ductile metal matrix with a high thermal conductivity, thus combining the best properties of both materials. Traditional applications of cermets include tank armor, vault armor, drill bits, and nuclear test-reactor fuel. Cermets with different ceramics (DUO{sub 2}, Al{sub 2}O{sub 3}, Gd{sub 2}O{sub 3}, etc.) are being investigated for the manufacture of SNF casks. Cermet casks offer four potential benefits: greater capacity (more SNF assemblies) for the same gross weight cask, greater capacity (more SNF assemblies) for the same external dimensions, improved resistance to assault, and superior repository performance. These benefits are achieved by varying the composition, volume fraction, and particulate size of the ceramic particles in the cermet with position in the cask body. Addition of depleted uranium dioxide (DUO{sub 2}) to the cermet increases shielding density, improves shielding effectiveness, and increases cask capacity for a given cask weight or size. Addition of low-density aluminium oxide (Al{sub 2}O{sub 3}) to the outer top and bottom sections of the cermet cask, where the radiation levels are lower, can lower cask weight without compromising shielding. The use of Al2O3 and other oxides, in appropriate locations, can increase resistance to assault. Repository performance may be improved by compositional control of the cask body to (1) create a local geochemical environment that slows the long-term degradation of the SNF and (2) enables the use of DUO{sub 2} for longterm criticality control. While the benefits of using cermets follow directly from their known properties, the primary challenge is to develop low-cost methods to fabricate

  1. Low-level measurement of alpha-particle emitting nuclei in ceramics and lead

    International Nuclear Information System (INIS)

    Nearly all natural materials contain trace quantities of uranium (U) and thorium (Th) and their daughter nuclides, many of which emit α-particles in their decay. Lead, at the end of the U-decay chain, typically contains some radioactive 210Pb which is chemically inseparable from the other Pb isotopes. α-particle emission from these decays can affect sensitive electronic components, such as memory chips or processors. Measurement of α-particle emitters can be accomplished by direct detection of the α-particles (which typically provides no positive identification of the emitting isotope because of energy loss in the sample) or by low-background γ-ray spectroscopy (which does provide positive identification via characteristic γ-rays). The latter is by far the best method for screening kg-sized samples of materials like ceramics, aluminum, iron, or copper. The difference between α counting and γ-ray spectroscopy is less for measuring 210Pb in Pb since the 46.5 keV characteristic γ-rays directly following the 210Pb decay are strongly absorbed and both methods are limited to thin layers. This paper discusses these two cases and concludes that a large n-type germanium γ-ray spectrometer is probably the best overall system for both measurements. (author)

  2. Micromechanical Modeling the Plastic Deformation of Particle-Reinforced Bulk Metallic Glass Composites

    Science.gov (United States)

    Jiang, Yunpeng; Shi, Xueping; Qiu, Kun

    2015-08-01

    A micromechanics model was employed to investigate the mechanical performance of particle-reinforced bulk metallic glass (BMG) composites. The roles of shear banding in the tensile deformation are accounted for in characterizing the strength and ductility of ductile particle-filled BMGs. For the sake of simplicity and convenience, shear band was considered to be a micro-crack in the present model. The strain-based Weibull probability distribution function and percolation theory were applied to describe the equivalent micro-crack evolution, which results in the progressive failure of BMG composites. Based on the developed model, the influences of shear bands on the plastic deformation were discussed for various microstructures. The predictions were in fairly good agreement with the experimental data from the literatures, which confirms that the developed analytical model is able to successfully describe the mechanical properties, such as yield strength, strain hardening, and stress softening elongation of composites. The present results will shed some light on optimizing the microstructures in effectively improving the tensile ductility of BMG composites.

  3. Sliding Wear Properties of Hybrid Aluminium Composite Reinforced by Particles of Palm Shell Activated Carbon and Slag

    Directory of Open Access Journals (Sweden)

    Zamri Yusoff

    2011-09-01

    Full Text Available In present work, dry sliding wear tests were conducted on hybrid composite reinforced with natural carbon based particles such as palm shell activated carbon (PSAC and slag. Hybrid composites containing 5 -20 wt.% of both reinforcements with average particles sizes about 125μm were prepared by conventional powder metallurgy technique, which involves the steps of mixing, compacting and sintering. Dry sliding experiments were conducted in air at room temperature using a pin-on-disc self-built attach to polisher machine. The disc which acted as the mating surface material was made of mild steel (120 HV cut from commercial mild steel sheet (2 mm thickness into 100mm diameter. The influence of the applied load was investigated under a constant sliding velocity of 0.1m/s with the applied loads at 3N, 11N and 51N. The contribution of the reinforcement content and the applied load as well as the sliding distance on the wear process and the wear rate have been investigated. The contribution of synergic factors such as applied load, sliding distance and reinforcement content (wt.% have been studied using analysis of variance (ANOVA. All synergic factors contribute to the wear process of all tested composites. Among synergic factors, the applied load is the highest contribution to wear process on both composites (Al/PSAC and Al/Slag and hybrid composite. The degree of improvement of wear resistance of hybrid composite is strongly dependent on the reinforcement content.

  4. Effect of Al alloys on selective laser melting behaviour and microstructure of in situ formed particle reinforced composites

    International Nuclear Information System (INIS)

    Highlights: ► Effect of Al alloy was examined on SLM facilitated in situ interaction with Fe2O3. ► The Al alloy influenced the SLM consolidation performance and the formed phases. ► In situ Al (alloy) composites were reinforced by ultrafine/nanoscale particles. ► The Al alloy affected the appearance of reinforced matrix. ► Enhanced solid solubility of matrix contributed to hardening. - Abstract: This work investigates the effects of various Al alloys (including Al, AlMg1SiCu, and AlSi10Mg), mixed with 15 wt% Fe2O3, on the selective laser melting (SLM) facilitated in situ reaction and formation of Al metal matrix composite (MMC) components. The results contribute to the development of medium/high strength Al composite parts which can be produced as complex net-shape products via the SLM process. Visual observation and computed tomography (CT) scanning reveal the best SLM consolidation performance and the lowest porosity for AlSi10Mg. SLM facilitated in situ reaction and subsequent rapid solidification introduce very fine particles (down to ∼50–100 nm), reinforcing the microstructure of all Al (alloy) composites. The particles are Al–Fe intermetallics, Al oxides such as α–Al2O3, plus Si crystals (alone or in combination) depending on the alloy composition. Ultrafine/nanoscale dendritic feature appears in the reinforced matrix of AlSi10Mg/15 wt%Fe2O3, in contrast with featureless matrix of Al/15 wt%Fe2O3. The in situ particle reinforced Al (alloy) composites are significantly harder than corresponding conventionally manufactured (e.g. casting) Al alloys without Fe2O3, due to superior microstructural characteristics such as featureless or very fine dendritic matrix, ultrafine/nanoscale particles, and also enhanced solid solubility of the SLM products.

  5. Effects of silica and calcium levels in nanobioglass ceramic particles on osteoblast proliferation

    International Nuclear Information System (INIS)

    At nanoscale, bioglass ceramic (nBGC) particles containing calcium oxide (lime), silica and phosphorus pentoxide promote osteoblast proliferation. However, the role of varied amounts of calcium and silica present in nBGC particles on osteoblast proliferation is not yet completely known. Hence, the current work was aimed at synthesizing two different nBGC particles with varied amounts of calcium oxide and silica, nBGC-1: SiO2:CaO:P2O5; mol% ∼ 70:25:5 and nBGC-2: SiO2:CaO:P2O5; mol% ∼ 64:31:5, and investigating their role on osteoblast proliferation. The synthesized nBGC particles were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. They exhibited their size at nanoscale and were non-toxic to human osteoblastic cells (MG-63). The nBGC-2 particles were found to have more effect on stimulation of osteoblast proliferation and promoted entering of more cells into G2/M cell cycle phase compared to nBGC-1 particles. There was a differential expression of cyclin proteins in MG-63 cells by nBGC-1 and nBGC-2 treatments, and the expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment. Thus, these results provide us a new insight in understanding the design of various nBGC particles by altering their ionic constituents with desirable biological properties thereby supporting bone augmentation. - Highlights: • nBGC particles with varied amounts of calcium and silica were synthesized. • They were non-toxic to human osteoblastic cells. • nBGC-2 particles had more effect on stimulation of osteoblast proliferation. • nBGC-2 particles promoted entering of osteoblasts into G2/M cell cycle phase. • Expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment

  6. Effect of particle size on microstructure and strength of porous spinel ceramics prepared by pore-forming in situ technique

    Indian Academy of Sciences (India)

    Wen Yan; Nan Li; Yuanyuan Li; Guangping Liu; Bingqiang Han; Juliang Xu

    2011-08-01

    The porous spinel ceramics were prepared from magnesite and bauxite by the pore-forming in situ technique. The characterization of porous spinel ceramics was determined by X-ray diffractometer (XRD), scanning electron microscopy(SEM), mercury porosimetry measurement etc and the effects of particle size on microstructure and strength were investigated. It was found that particle size affects strongly on the microstructure and strength. With decreasing particle size, the pore size distribution occurs from multi-peak mode to bi-peak mode, and lastly to mono-peak mode; the porosity decreases but strength increases. The most apposite mode is the specimens from the grinded powder with a particle size of 6.53 m, which has a high apparent porosity (40%), a high compressive strength (75.6MPa), a small average pore size (2.53 m) and a homogeneous pore size distribution.

  7. Impact of Particle Size of Ceramic Granule Blends on Mechanical Strength and Porosity of 3D Printed Scaffolds

    OpenAIRE

    Sebastian Spath; Philipp Drescher; Hermann Seitz

    2015-01-01

    3D printing is a promising method for the fabrication of scaffolds in the field of bone tissue engineering. To date, the mechanical strength of 3D printed ceramic scaffolds is not sufficient for a variety of applications in the reconstructive surgery. Mechanical strength is directly in relation with the porosity of the 3D printed scaffolds. The porosity is directly influenced by particle size and particle-size distribution of the raw material. To investigate this impact, a hydroxyapatite gran...

  8. Effects of different lasers and particle abrasion on surface characteristics of zirconia ceramics.

    Directory of Open Access Journals (Sweden)

    Sakineh Arami

    2014-04-01

    Full Text Available The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP after surface treatment with lasers and airborne-particle abrasion.First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7 and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ and no treatment (controls. Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM.According to ANOVA and Tukey's test, the mean surface roughness (Ra after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers.Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic.

  9. Mechanical and thermal properties of bio-composites based on polypropylene reinforced with Nut-shells of Argan particles

    International Nuclear Information System (INIS)

    Highlights: ► Nuts-shells of Argan particles are used as reinforcement in thermoplastic matrix. ► Particles are homogeneously dispersed and distributed within PP matrix. ► Mechanical and thermal characterization of the composite are applied. ► Particles–matrix adhesion was assured by the use of a SBS compatibilizer. - Abstract: This study treats the combined effects of both particle sizes and particle loading on the mechanical and thermal properties of polypropylene (PP) composites reinforced with Nut-shells of Argan (NA) particles. Three range sizes of particles were used in the presence of a polypropylene matrix grafted with 8 wt.% of a linear block copolymer based on styrene and butadiene coupling agent, to improve adhesion between the particles and the matrix. The composites were prepared through melt-blending using an internal mixer and the tensile specimens were prepared using a hot press molding machine. Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Thermo Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA) and tensile tests were employed to characterize the composites at 10, 15, 20 and 25 wt.% particle contents. Results show a clear improvement in Young’s modulus from the use of particles when compared to the neat PP, a gain of 42.65%, 26.7% and 2.9% at 20 wt.% particle loading, for particle range 1, 2 and 3, respectively. In addition a notable increase in the Young’s modulus was observed when decrease the particle size. The thermal stability of composites exhibits a slight decrease (256–230 °C) with particles loading from 10 to 25 wt.%, against neat PP (258 °C)

  10. Development of Thermal Spraying and Coating Techniques by Using Thixotropic Slurries Including Metals and Ceramics Particles

    International Nuclear Information System (INIS)

    Thermal nanoparticles coating and microlines patterning were newly developed as novel technologies to fabricate fine ceramics layers and geometrical intermetallics patterns for mechanical properties modulations of practical alloys substrates. Nanometer sized alumina particles were dispersed into acrylic liquid resins, and the obtained slurries were sputtered by using compressed air jet. The slurry mists could blow into the arc plasma with argon gas spraying. On stainless steels substrates, the fine surface layers with high wear resistance were formed. In cross sectional microstructures of the coated layers, micromater sized cracks or pores were not observed. Subsequently, pure aluminum particles were dispersed into photo solidified acrylic resins, and the slurry was spread on the stainless steel substrates by using a mechanical knife blade. On the substrates, microline patterns with self similar fractal structures were drawn and fixed by using scanning of an ultra violet laser beam. The patterned pure metal particles were heated by the argon arc plasma spray assisting, and the intermetallics or alloys phases with high hardness were created through reaction diffusions. Microstructures in the coated layers and the patterned lines were observed by using a scanning electron microscopy.

  11. Mesoscopic bead-and-spring model of hard spherical particles in a rubber matrix. I. Hydrodynamic reinforcement

    Science.gov (United States)

    Raos, Guido; Allegra, Giuseppe

    2000-11-01

    Exploiting an electrostatic analogy, we show that the elastic forces between a set of rigid particles embedded in a phantom polymer network can be represented by a simple bead-and-spring model. The beads represent the particles and the springs the rubber matrix. The model is validated by Monte Carlo simulation of rubbers filled with hard spherical particles, at volume fractions between 0.1 and 0.3. We derive both the moduli and the full stress-strain curves, under uniaxial elongation. The model reproduces and extends previous theoretical results on the so-called hydrodynamic reinforcement effect.

  12. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  13. The Effect of Particle Size of Pore Forming Agent on the Hydroxyapatite Ceramic Microstructure

    OpenAIRE

    Zālīte, V; Ločs, J; Freimanis, I; Jakovļevs, D; Bērziņa-Cimdiņa, L

    2010-01-01

    In current research was obtained porous hydroxyapatite (HAp) ceramic using pore forming agent NH4HCO3. The aim of this study was to investigate the effect of selected NH4HCO3 fractions on the HAp ceramic microstructure. The porosity of the obtained ceramics was determined using Archimedes method. The scanning electron microscopy was used for the evaluation of microstructure.

  14. Metallic nano-particles in lustre glazed ceramics from the 15th century in Seville studied by PIXE and RBS

    Energy Technology Data Exchange (ETDEWEB)

    Polvorinos del Rio, A. [Departamento de Cristallografia, Mineralogia y Quimica Agricola, Universidad de Sevilla, avenida Reina Mercedes s/n (Spain); Castaing, J. [Laboratoire du centre de recherche et de restauration des musees de France C2RMF CNRS UMR 171, Plais du Louvre, 14 quai Francois Mitterrand, 75001 Paris (France)]. E-mail: jacques.castaing@culture.fr; Aucouturier, M. [Laboratoire du centre de recherche et de restauration des musees de France C2RMF CNRS UMR 171, Plais du Louvre, 14 quai Francois Mitterrand, 75001 Paris (France)

    2006-08-15

    Lustre ceramics, found in a workshop located in Triana (Sevilla), have been analysed to determine the composition of glazes including the metallic particle layers giving rise to the lustre effect. PIXE and RBS were used for the elemental composition and the sub-surface concentration profiles, respectively. Copper and silver at the origin of the lustre are detected by PIXE. RBS gives access to the detailed distribution of the elements in the surface layers. The simulation of RBS spectra confirms the occurrence of thin layers (less than 300 nm) containing metallic silver and/or copper. The results are compared with those obtained on other types of lustre ceramics.

  15. Metallic nano-particles in lustre glazed ceramics from the 15th century in Seville studied by PIXE and RBS

    International Nuclear Information System (INIS)

    Lustre ceramics, found in a workshop located in Triana (Sevilla), have been analysed to determine the composition of glazes including the metallic particle layers giving rise to the lustre effect. PIXE and RBS were used for the elemental composition and the sub-surface concentration profiles, respectively. Copper and silver at the origin of the lustre are detected by PIXE. RBS gives access to the detailed distribution of the elements in the surface layers. The simulation of RBS spectra confirms the occurrence of thin layers (less than 300 nm) containing metallic silver and/or copper. The results are compared with those obtained on other types of lustre ceramics

  16. Effect of silica particles modified by in-situ and ex-situ methods on the reinforcement of silicone rubber

    International Nuclear Information System (INIS)

    Highlights: • In-situ and ex-situ methods were applied to modify silica particles. • In-situ method was more beneficial to preparing silica particles with high BET surface area. • Silicone rubber filled with in-situ modified silica exhibits excellent mechanical and thermal properties. - Abstract: In-situ and ex-situ methods were applied to modify silica particles in order to investigate their effects on the reinforcement of silicone rubber. Surface area and pore analyzer, laser particle size analyzer, Fourier-transform infrared spectroscopy (FTIR), contact-angle instrument, and transmission electron microscope (TEM) were utilized to investigate the structure and properties of the modified silica particles. Dynamic mechanical thermal analyzer (DMTA) was employed to characterize the vulcanizing behavior and mechanical properties of the composites. Thermogravimetric analysis (TGA) was performed to test the thermal stability of the composites. FTIR and contact angle analysis indicated that silica particles were successfully modified by these two methods. The BET surface area and TEM results reflected that in-situ modification was more beneficial to preparing silica particles with irregular shape and higher BET surface area in comparison with ex-situ modification. The DMTA and TGA data revealed that compared with ex-situ modification, the in-situ modification produced positive influence on the reinforcement of silicone rubber

  17. Evaluation of the Technical-Economic Potential of Particle- Reinforced Aluminum Matrix Composites and Electrochemical Machining

    Science.gov (United States)

    Schubert, A.; Götze, U.; Hackert-Oschätzchen, M.; Lehnert, N.; Herold, F.; Meichsner, G.; Schmidt, A.

    2016-03-01

    Compared to conventional cutting, the processing of materials by electrochemical machining offers some technical advantages like high surface quality, no thermal or mechanical impact on the work piece and preservation of the microstructure of the work piece material. From the economic point of view, the possibility of process parallelization and the absence of any process-related tool wear are mentionable advantages of electrochemical machining. In this study, based on experimental results, it will be evaluated to what extent the electrochemical machining is technically and economically suitable for the finish-machining of particle- reinforced aluminum matrix composites (AMCs). Initial studies showed that electrochemical machining - in contrast to other machining processes - has the potential to fulfil demanding requirements regarding precision and surface quality of products or components especially when applied to AMCs. In addition, the investigations show that processing of AMCs by electrochemical machining requires less energy than the electrochemical machining of stainless steel. Therefore, an evaluation of electrochemically machined AMCs - compared to stainless steel - from a technical and an economic perspective will be presented in this paper. The results show the potential of electro-chemically machined AMCs and contribute to the enhancement of instruments for technical-economic evaluations as well as a comprehensive innovation control.

  18. Non-magnetic interface of magnetic particles in nanostructured glass ceramics studied by SANS

    International Nuclear Information System (INIS)

    Complete text of publication follows. Nanosized crystallites of ferrimagnetic magnetite, Fe3O4, were prepared by heat treatment of a silicate glass. The magnetic properties of the glass ceramic strongly depend on the heat treatment conditions with a significant maximum of the specific saturation magnetisation for the heat treatment of 2 h at T = 700 deg C. Previous SANS investigations [1] of this sample revealed bimodal size distribution of the nanocrystalline phase with maxima centred at diameters of about 5 nm and 20 nm, respectively. Both size grades of particles consist of magnetite. SANS provided the result that the magnetically active core of the magnetite nanocrystals is surrounded by a non-magnetic surface layer. Three SANS experiments are reported which clarified the nature of the interface regions. First, the time dependence of the scattering profiles during isothermal annealing at 700 deg C allowed the evolution of non-magnetic interface region to be determined. The temperature and field variations of the magnetic scattering revealed the nature of the magnetic couplings in the nanocrystalline spinel structure. Employing the advanced technique of polarised neutrons it is clearly shown that the size of the magnetic core is uniquely correlated with that of the whole Fe3O4 particle. (author) [1] U. Lembke et al, J. Appl. Phys., 85/4 (1999) 2279

  19. Microstructure and strain rate effects on the mechanical behavior of particle reinforced epoxy-based reactive materials

    Science.gov (United States)

    White, Bradley William

    The effects of reactive metal particles on the microstructure and mechanical properties of epoxy-based composites is investigated in this work. Particle reinforced polymer composites show promise as structural energetic materials that can provide structural strength while simultaneously being capable of releasing large amounts of chemical energy through highly exothermic reactions occurring between the particles and with the matrix. This advanced class of materials is advantageous due to the decreased amount of high density inert casings needed for typical energetic materials and for their ability to increase payload expectancy and decrease collateral damage. Structural energetic materials can be comprised of reactive particles that undergo thermite or intermetallic reactions. In this work nickel (Ni) and aluminum (Al) particles were chosen as reinforcing constituents due to their well characterized mechanical and energetic properties. Although, the reactivity of nickel and aluminum is well characterized, the effects of their particle size, volume fractions, and spatial distribution on the mechanical behavior of the epoxy matrix and composite, across a large range of strain rates, are not well understood. To examine these effects castings of epoxy reinforced with 20--40 vol.% Al and 0--10 vol.% Ni were prepared, while varying the aluminum nominal particle size from 5 to 50 mum and holding the nickel nominal particle size constant at 50 mum. Through these variations eight composite materials were produced, possessing unique microstructures exhibiting different particle spatial distributions and constituent makeup. In order to correlate the microstructure to the constitutive response of the composites, techniques such as nearest-neighbor distances, and multiscale analysis of area fractions (MSAAF) were used to quantitatively characterize the microstructures. The composites were investigated under quasi-static and dynamic compressive loading conditions to characterize

  20. Physical and Mechanical Properties of LoVAR: A New Lightweight Particle-Reinforced Fe-36Ni Alloy

    Science.gov (United States)

    Stephenson, Timothy; Tricker, David; Tarrant, Andrew; Michel, Robert; Clune, Jason

    2015-01-01

    Fe-36Ni is an alloy of choice for low thermal expansion coefficient (CTE) for optical, instrument and electrical applications in particular where dimensional stability is critical. This paper outlines the development of a particle-reinforced Fe-36Ni alloy that offers reduced density and lower CTE compared to the matrix alloy. A summary of processing capability will be given relating the composition and microstructure to mechanical and physical properties.

  1. Composite materials based on AlMg1SiCu aluminium alloy reinforced with halloysite particles

    OpenAIRE

    Tomiczek, B.; L.A. Dobrzański

    2013-01-01

    Purpose: The present work describes microstructure and technological, as well as mechanical properties of AlMg1SiCu matrix composite materials reinforced with halloysite particles by powder metallurgy techniques and hot extrusion. Design/methodology/approach: Mechanical milling, compacting and hot extrusion successively are considering as a method for manufacturing metal composite powders with a controlled fine microstructure and enhanced mechanical properties. Findings:...

  2. Study on dry friction and wear resistance of a WC-Co particle reinforced iron matrix composite material

    OpenAIRE

    Zhang Peng; Zeng Shaolian; Zhang Zhiguo

    2013-01-01

    In order to select a suitable material for the rolling mill guide application, the dry sliding friction and wear resistance of a tungsten carbide combining cobalt (WC-Co) particle reinforced chromium cast iron composite material were studied. In particular, the wear resistance was discussed in detail. The results showed that the composite material demonstrates 25 times the wear resistance of high Cr cast iron, and 9 times the wear resistance of heat resistant steel. However, the average frict...

  3. Microstructures and Mechanical Properties of TiC Particle Reinforced TiAl Composites by Spark Plasma Sintering

    Institute of Scientific and Technical Information of China (English)

    YUE Yunlong; WU Haitao; WU Bo; WANG Zhijie; YIN Haiyan; SU Tong

    2007-01-01

    Using spark plasma sintering(SPS) technique, TiC particle reinforced γ-TiAl composites were prepared with varying weight fraction of TiC powders. The effects of the TiC fractions and distributions on the properties of the composites were investigated. The composite containing 7wt% TiC had the optimum three-point bending strength of 842 MPa,which was 200 MPa greater than that of the unreinforced γ-TiAl intermetallic. The degradation of the bending strength occurred in the composites containing more than 7wt% TiC and this was believed to be attributed to agglomerated particles of TiC, which acted as crack initiation and propagation sites. The increase of strength in TiC reinforced IMCs came from the grain refinement and the interaction of dislocations with the reinforcing particles. The bending strength of the IMC containing 7wt% TiC was theoretically estimated to increase by 85 MPa and 200 MPa, respectively, by the grain refinement and dislocation strengthening, the total of which was almost in accordance with the improvement in that of the unreinforced γ-TiAl intermetallic when considering normal estimation errors.

  4. Optimization of the Infrastructure of Reinforced Concrete Reservoirs by a Particle Swarm Algorithm

    Science.gov (United States)

    Kia, Saeed; Sebt, Mohammad Hassan; Shahhosseini, Vahid

    2015-03-01

    Optimization techniques may be effective in finding the best modeling and shapes for reinforced concrete reservoirs (RCR) to improve their durability and mechanical behavior, particularly for avoiding or reducing the bending moments in these structures. RCRs are one of the major structures applied for reserving fluids to be used in drinking water networks. Usually, these structures have fixed shapes which are designed and calculated based on input discharges, the conditions of the structure's topology, and geotechnical locations with various combinations of static and dynamic loads. In this research, the elements of reservoir walls are first typed according to the performance analyzed; then the range of the membrane based on the thickness and the minimum and maximum cross sections of the bar used are determined in each element. This is done by considering the variable constraints, which are estimated by the maximum stress capacity. In the next phase, based on the reservoir analysis and using the algorithm of the PARIS connector, the related information is combined with the code for the PSO algorithm, i.e., an algorithm for a swarming search, to determine the optimum thickness of the cross sections for the reservoir membrane's elements and the optimum cross section of the bar used. Based on very complex mathematical linear models for the correct embedding and angles related to achain of peripheral strengthening membranes, which optimize the vibration of the structure, a mutual relation is selected between the modeling software and the code for a particle swarm optimization algorithm. Finally, the comparative weight of the concrete reservoir optimized by the peripheral strengthening membrane is analyzed using common methods. This analysis shows a 19% decrease in the bar's weight, a 20% decrease in the concrete's weight, and a minimum 13% saving in construction costs according to the items of a checklist for a concrete reservoir at 10,000 m3.

  5. Optimization of the Infrastructure of Reinforced Concrete Reservoirs by a Particle Swarm Algorithm

    Directory of Open Access Journals (Sweden)

    Kia Saeed

    2015-03-01

    Full Text Available Optimization techniques may be effective in finding the best modeling and shapes for reinforced concrete reservoirs (RCR to improve their durability and mechanical behavior, particularly for avoiding or reducing the bending moments in these structures. RCRs are one of the major structures applied for reserving fluids to be used in drinking water networks. Usually, these structures have fixed shapes which are designed and calculated based on input discharges, the conditions of the structure's topology, and geotechnical locations with various combinations of static and dynamic loads. In this research, the elements of reservoir walls are first typed according to the performance analyzed; then the range of the membrane based on the thickness and the minimum and maximum cross sections of the bar used are determined in each element. This is done by considering the variable constraints, which are estimated by the maximum stress capacity. In the next phase, based on the reservoir analysis and using the algorithm of the PARIS connector, the related information is combined with the code for the PSO algorithm, i.e., an algorithm for a swarming search, to determine the optimum thickness of the cross sections for the reservoir membrane’s elements and the optimum cross section of the bar used. Based on very complex mathematical linear models for the correct embedding and angles related to achain of peripheral strengthening membranes, which optimize the vibration of the structure, a mutual relation is selected between the modeling software and the code for a particle swarm optimization algorithm. Finally, the comparative weight of the concrete reservoir optimized by the peripheral strengthening membrane is analyzed using common methods. This analysis shows a 19% decrease in the bar’s weight, a 20% decrease in the concrete’s weight, and a minimum 13% saving in construction costs according to the items of a checklist for a concrete reservoir at 10,000 m3.

  6. Microstructure and Mechanical Properties of Cr-SiC Particles-Reinforced Fe-Based Alloy Coating

    Science.gov (United States)

    Wang, Fu-cheng; Du, Xiao-dong; Zhan, Ma-ji; Lang, Jing-wei; Zhou, Dan; Liu, Guang-fu; Shen, Jian

    2015-12-01

    In this study, SiC particles were first coated with Cr to form a layer that can protect the SiC particles from dissolution in the molten pool. Then, the Cr-SiC powder was injected into the tail of molten pool during plasma-transferred arc welding process (PTAW), where the temperature was relatively low, to prepare Cr-SiC particles reinforced Fe-based alloy coating. The microstructure and phase composition of the powder and surface coatings were analyzed, and the element distribution and hardness at the interfacial region were also evaluated. The protective layer consists of Cr3Si, Cr7C3, and Cr23C6, which play an important role in the microstructure and mechanical properties. The protective layer is dissolved in the molten pool forming a flocculent region and a transition region between the SiC particles and the matrix. The tribological performance of the coating was also assessed using a ring-block sliding wear tester with GGr15 grinding ring under 490 and 980 N load. Cr-SiC particles-reinforced coating has a lower wear rate than the unreinforced coating.

  7. SiC fiber-reinforced glass-ceramic composites in the zirconia/magnesium aluminosilicate system

    International Nuclear Information System (INIS)

    Glass-ceramic matrix compositions derived from metal alkoxides were vacuum hot-pressed. The compositions were nominally cordierite, with variations in silica content, and additions of up to 30% zirconia. Composites fabricated by vacuum hot-pressing the matrix compositions with SiC Nicalon fibers were also studied. Variations in pressing conditions and subsequent heat treatments were examined. Crystalline phase development, bend strength and fracture toughness were evaluated as a function of hot-pressing parameters

  8. Corrosion resistance of enamel coating modified by calcium silicate and sand particle for steel reinforcement in concrete

    Science.gov (United States)

    Tang, Fujian

    Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study. The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution by OCP, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The coatings include a pure enamel, a mixed enamel that consists of 50% pure enamel and 50% calcium silicate by weight, and a double enamel that has an inner pure enamel layer and an outer mixed enamel layer. Electrochemical tests demonstrates that both pure and double enamel coatings can significantly improve corrosion resistance, while the mixed enamel coating offers very little protection due to connected channels. The second paper is focused on the electrochemical characteristics of enamel coating modified by sand particle applied to reinforcing steel bar in 3.5 wt% NaCl solution by EIS. Six percentages by weight are considered including 5%, 10%, 20%, 30%, 50%, and 70%. Results reveal that addition of sand particle does not affect its corrosion resistance significantly. Most of the sand particles can wet very well with enamel body, while some have a weak zone which is induced during the cooling stage due to different coefficient of thermal expansion. Therefore, quality control of sand particle is the key factor to improve its corrosion resistance.

  9. Development of the lithium fuel particles with ceramic coating for testing the tritium production in the HTTR reactor

    International Nuclear Information System (INIS)

    The method for obtained tritium by means of the lithium fuel particles with ceramic coating (LPCC), irradiated in the HTTR high-temperature gaseous reactor, and the results of tests on the hermeticity of such particles at the temperature of 1400 K are described. The basic characteristics of the LPCC with two coating layers and coefficients of the lithium diffusion in certain metals and ceramic materials are presented. The design for applying coatings on the LPCC by means of a pseudoliquified layer is described. The chemical stability and mechanical integrity of the LPCC were subjected to tests on their hermeticity at the temperature, expected in the irradiation zone. It is also shown, that 0.1 g of tritium may be obtained annually in one LPCC

  10. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  11. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-06-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  12. Study on dry friction and wear resistance of a WC-Co particle reinforced iron matrix composite material

    Directory of Open Access Journals (Sweden)

    Zhang Peng

    2013-05-01

    Full Text Available In order to select a suitable material for the rolling mill guide application, the dry sliding friction and wear resistance of a tungsten carbide combining cobalt (WC-Co particle reinforced chromium cast iron composite material were studied. In particular, the wear resistance was discussed in detail. The results showed that the composite material demonstrates 25 times the wear resistance of high Cr cast iron, and 9 times the wear resistance of heat resistant steel. However, the average friction factor in the stable friction stage showed a relationship of μComposites/45 # steel > μHigh chromium cast iron/45 # steel > μHeat resistant steel/45 # steel. The wear resistance mechanism of the composite material was associated with the reinforcing particles, which protruded from the worn surface to bear the friction load when the matrix material surface was worn, thereby reducing the abrasive and adhesive wear. In addition, the matrix material possessed suitable hardness and toughness, providing a support to the reinforcements.

  13. Effect of particle size on the in vitro bioactivity, hydrophilicity and mechanical properties of bioactive glass-reinforced polycaprolactone composites

    International Nuclear Information System (INIS)

    Polycaprolactone (PCL) composite films containing 5 wt.% bioactive glass (BG) particles of different sizes (6 μm, 250 nm, 3) and sodium calcium silicate (Na2CaSiO4) phases were formed. The introduction of submicron BG particles (250 nm) was shown to improve the bioactivity of PCL films. In contrast to BG microparticles, the submicron BG particles were distributed on the film surfaces, providing a high surface exposure to SBF with an improved nanotopography. A notable increase in the stiffness and elastic modulus of the composite was also obtained. As compared to submicron BG particles, lower bioactivity and elastic modulus were acquired for PCL/BG nanoparticles. It was also shown that in spite of high specific surface area of the nanoparticles, partial crystallization during mechanical milling and agglomeration of the nanoparticles during processing decrease the bioactivity, hydrophilicity and mechanical response of the BG-reinforced PCL composites. Highlights: → The effect of Bioglass particle size on the in vitro bioactivity of polycaprolactone/Bioglass composites was studied. → Partial crystallization of bioactive glass particles during high-energy mechanical milling was shown. → The submicron BG particles (250 nm) were shown to improve the bioactivity of PCL films. → Lower bioactivity was acquired for the nanocomposite due to agglomeration and partial crystallization. → The hydrophilicity and elastic modulus of the composites were shown to depend on the size of Bioglass particles.

  14. Crack initiation and propagation behavior of WC particles reinforced Fe-based metal matrix composite produced by laser melting deposition

    Science.gov (United States)

    Wang, Jiandong; Li, Liqun; Tao, Wang

    2016-08-01

    It is generally believed that cracks in metal matrix composites (MMC) parts manufacturing are crucial to the reliable material properties, especially for the reinforcement particles with high volume fraction. In this paper, WC particles (WCp) reinforced Fe-based metal matrix composites (WCp/Fe) were manufactured by laser melting deposition (LMD) technology to investigate the characteristics of cracks formation. The section morphology of composites were analyzed by optical microscope (OM), and microstructure of WCp, matrix and interface were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), in order to study the crack initiation and propagation behavior under different laser process conditions. The temperature of materials during the laser melting deposition was detected by the infrared thermometer. The results showed that the cracks often appeared after five layers laser deposition in this experiment. The cracks crossed through WC particles rather than the interface, so the strength of interface obtained by the LMD was relatively large. When the thermal stress induced by high temperature gradient during LMD and the coefficient of thermal expansion mismatch between WC and matrix was larger than yield strength of WC, the cracks would initiate inside WC particle. Cracks mostly propagated along the eutectic phases whose brittleness was very large. The obtained thin interface was beneficial to transmitting the stress from particle to matrix. The influence of volume fraction of particles, laser power and scanning speed on cracks were investigated. This paper investigated the influence of WC particles size on cracks systematically, and the smallest size of cracked WC in different laser processing parameters was also researched.

  15. Effect of kaolin particle size and loading on the characteristics of kaolin ceramic support prepared via phase inversion technique

    OpenAIRE

    Siti Khadijah Hubadillah; Zawati Harun; Mohd Hafiz Dzarfan Othman; A. F. ISMAIL; Paran Gani

    2016-01-01

    In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04–0.6 μm (denoted as type A) and 10–15 μm (denoted as type B), at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. Th...

  16. Fabrication of Al5083 surface composites reinforced by CNTs and cerium oxide nano particles via friction stir processing

    International Nuclear Information System (INIS)

    Highlights: • Using friction stir processing, an effect of CNTs and CeO2 reinforcements on mechanical and corrosion properties of Al5083 alloy is reported. • The strength of Al5083 was increased by 42%, its matrix grain size reduced five times, and hardness was doubled by the incorporation of CNTs-CeO2 mixture in the volume ratio of 75-25 respectively. • Unlike the CNTs, incorporation of nanosized CeO2 particles resulted in remarkable increase in pitting resistance of the alloy. - Abstract: In the present investigation, friction stir processing (FSP) was utilized to incorporate Multi Walled Carbon Nano Tubes (MWCNT) and nanosized cerium oxide particles into the matrix of Al5083 alloy to form surface reinforced composites. The effect of these nanosized reinforcements either separately or in the combined form, on microstructural modification, mechanical properties and corrosion resistance of FSPed Al5083 surface composites was studied. A threaded cylindrical hardened steel tool was used with the rotation speeds of 600 and 800 rpm and travel speeds of 35 and 45 mm/min and a tilt angle of 5°. Mechanical properties and corrosion resistance of FSPed samples were evaluated and compared with the base alloy. The maximum tensile strength and hardness value were achieved for the hybrid composite containing a mixture of CNTs and cerium oxide in the volume ratio of 75-25, respectively, whereas a significant increase in pitting resistance of the base alloy was obtained when cerium oxide alone was incorporated. The corrosion behavior of the samples was investigated by potentiodynamic polarization tests and assessed in term of pitting potential and passivation range. Microstructural analysis carried out by using optical and electron microscopes showed that reinforcements are well dispersed inside the nugget zone (NZ), and remarkable grain refinement is gained. The study was aimed to fabricate surface composites with improved mechanical properties and corrosion resistance

  17. Fabrication of Al5083 surface composites reinforced by CNTs and cerium oxide nano particles via friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, S.A. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Ranjbar, Khalil, E-mail: k_ranjbar@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Dehmolaei, R. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Amirani, A.R. [12th Ghaem Street, Bld. Hashemzadeh, Shahrak Golestan, Tehran (Iran, Islamic Republic of)

    2015-02-15

    Highlights: • Using friction stir processing, an effect of CNTs and CeO{sub 2} reinforcements on mechanical and corrosion properties of Al5083 alloy is reported. • The strength of Al5083 was increased by 42%, its matrix grain size reduced five times, and hardness was doubled by the incorporation of CNTs-CeO{sub 2} mixture in the volume ratio of 75-25 respectively. • Unlike the CNTs, incorporation of nanosized CeO{sub 2} particles resulted in remarkable increase in pitting resistance of the alloy. - Abstract: In the present investigation, friction stir processing (FSP) was utilized to incorporate Multi Walled Carbon Nano Tubes (MWCNT) and nanosized cerium oxide particles into the matrix of Al5083 alloy to form surface reinforced composites. The effect of these nanosized reinforcements either separately or in the combined form, on microstructural modification, mechanical properties and corrosion resistance of FSPed Al5083 surface composites was studied. A threaded cylindrical hardened steel tool was used with the rotation speeds of 600 and 800 rpm and travel speeds of 35 and 45 mm/min and a tilt angle of 5°. Mechanical properties and corrosion resistance of FSPed samples were evaluated and compared with the base alloy. The maximum tensile strength and hardness value were achieved for the hybrid composite containing a mixture of CNTs and cerium oxide in the volume ratio of 75-25, respectively, whereas a significant increase in pitting resistance of the base alloy was obtained when cerium oxide alone was incorporated. The corrosion behavior of the samples was investigated by potentiodynamic polarization tests and assessed in term of pitting potential and passivation range. Microstructural analysis carried out by using optical and electron microscopes showed that reinforcements are well dispersed inside the nugget zone (NZ), and remarkable grain refinement is gained. The study was aimed to fabricate surface composites with improved mechanical properties and

  18. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Chaopeng; Gao, Yimin; Zhou, Yucheng [Xi' an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Xi' an, Shaanxi Province (China); Wei, Shizhong [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China); Henan University of Science and Technology, Engineering Research Center of Tribology and Materials Protection, Ministry of Education, Luoyang (China); Zhang, Guoshang; Zhu, Xiangwei; Guo, Songliang [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China)

    2016-03-15

    The nano-sized ZrO{sub 2}-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO{sub 2} particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO{sub 2} particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO{sub 2} particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. (orig.)

  19. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO2 particles

    International Nuclear Information System (INIS)

    The nano-sized ZrO2-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO2 particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO2 particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO2 particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. (orig.)

  20. Method Developed for the High-Temperature Nondestructive Evaluation of Fiber-Reinforced Silicon Carbide Ceramic Matrix Composites

    Science.gov (United States)

    Goldsby, Jon C.

    1998-01-01

    Ceramic matrix composites have emerged as candidate materials to allow higher operating temperatures (1000 to 1400 C) in gas turbine engines. A need, therefore, exists to develop nondestructive methods to evaluate material integrity at the material operating temperature by monitoring thermal and mechanical fatigue. These methods would also have potential as quality inspection tools. The goal of this investigation at the NASA Lewis Research Center is to survey and correlate the temperature-dependent damping and stiffness of advanced ceramic composite materials with imposed thermal and stress histories that simulate in-service turbine engine conditions. A typical sample size of 100 by 4 by 2 cubic millimeters, along with the specified stiffness and density, placed the fundamental vibration frequencies between 100 and 2000 Hz. A modified Forster apparatus seemed most applicable to simultaneously measure both damping and stiffness. Testing in vacuum reduced the effects of air on the measurements. In this method, a single composite sample is vibrated at its fundamental tone; then suddenly, the mechanical excitation is removed so that the sample's motion freely decays with time. Typical results are illlustrated in this paper.

  1. Impact of Particle Size of Ceramic Granule Blends on Mechanical Strength and Porosity of 3D Printed Scaffolds

    Directory of Open Access Journals (Sweden)

    Sebastian Spath

    2015-07-01

    Full Text Available 3D printing is a promising method for the fabrication of scaffolds in the field of bone tissue engineering. To date, the mechanical strength of 3D printed ceramic scaffolds is not sufficient for a variety of applications in the reconstructive surgery. Mechanical strength is directly in relation with the porosity of the 3D printed scaffolds. The porosity is directly influenced by particle size and particle-size distribution of the raw material. To investigate this impact, a hydroxyapatite granule blend with a wide particle size distribution was fractioned by sieving. The specific fractions and bimodal mixtures of the sieved granule blend were used to 3D print specimens. It has been shown that an optimized arrangement of fractions with large and small particles can provide 3D printed specimens with good mechanical strength due to a higher packing density. An increase of mechanical strength can possibly expand the application area of 3D printed hydroxyapatite scaffolds.

  2. Carbon oxidation in ceramic composites and the evaluation of interfacial sealing for oxidation resistant fiber-reinforced composite systems

    Science.gov (United States)

    Glime, William Harrison, III

    1997-11-01

    Carbon offers desirable properties as a fiber-matrix interphase material in ceramic matrix composites (CMC's), but oxidation of carbon at temperatures above 500sp°C has limited its utility. In an effort to better understand the kinetics associated with carbon oxidation pertaining to CMC applications, the origin of non-planar morphologies observed in the reaction front of carbon fibers and interphases receding into a ceramic matrix in the temperature range of 700sp°C to 1000sp°C was analyzed. A numerical simulation based on the finite difference method is utilized to evaluate the parameters which govern the morphology of the receding carbon reaction front. The study indicates that the morphology of the reaction front contains information regarding the interplay between oxidation behavior and microstructural features of the carbon. Carbon oxidation was found to obey "weak-link" behavior, that is, a sub-component which is more susceptible to oxidation governs the recession kinetics. The implications of weak link oxidation to preservation of a carbon interphase in a ceramic composite are discussed. Interrupted interphases have demonstrated the ability to confine oxidation of a carbon interphase to a localized region adjacent to a matrix crack. Commercial SiC mono-filaments (SCS-6, Textron Specialty Materials) were modified with a laser to produce fibers with discontinuous carbon coatings that were used in experiments to study mechanical properties. The laser-scribed fibers were tested in isolation, used in single-fiber microcomposites, or incorporated into small bulk composite specimens using a powder processing route to produce the matrix. The mechanical performance of the various types of specimens prepared using the laser scribing technique is presented and these results are used in a simulation of ultimate composite properties. The effect of fiber matrix fusion, by direct bonding or through a reaction product which seals the interface, was investigated with

  3. The fracture toughness and DBTT of MoB particle-reinforced MoSi2 composites

    International Nuclear Information System (INIS)

    The room temperature fracture toughness and the high temperature DBTT of MoB particle-reinforced MoSi2 composites were investigated using Vickers indentation technique and MSP testing method, respectively. Modified small punch (MSP) test is a method for evaluation of mechanical properties using very small specimens, and it's appropriate for the determination of strength and DBTT. It was found that the approximate fracture toughness of the composite is 1.3 times that of monolithic MoSi2, and its DBTT is 100 C higher than that of monolithic MoSi2 materials. Cracks deflection is a probable mechanism responsible for this behavior. (orig.)

  4. Aluminium AA6061 Matrix Composite Reinforced with Spherical Alumina Particles Produced by Infiltration: Perspective on Aerospace Applications

    OpenAIRE

    Claudio Bacciarini; Vincent Mathier

    2014-01-01

    Metal matrix composites, based on AA6061 reinforced with 60 vol% Al2O3 spherical particles, were produced by gas pressure infiltration and characterized for hardness, impulse excitation modulus, tensile properties (at room temperature and at 250°C), and machining. It was experimentally demonstrated that the novel alumina powder used in the present work does not react with the liquid Mg-containing matrix during the infiltration process. The AA6061 matrix therefore retains its ability to be str...

  5. Microstructure and mechanical properties of aluminum alloy matrix composites reinforced with Fe-based metallic glass particles

    International Nuclear Information System (INIS)

    Highlights: • Al-2024/FMG composites have been prepared by powder metallurgy method. • Mechanical milling resulted in significant grain refinement of the Al matrix. • The high strength is attributed to the refined microstructure and FMG particles. - Abstract: Fe-based metallic glass (FMG) particles reinforced Al-2024 matrix composites were fabricated by using the powder metallurgy method successfully. Mechanical alloying result in nanostructured Al-2024 matrix with a grain size of about 30 nm together with a good distribution of the FMG particles in the Al matrix. The consolidation of the composites was performed at a temperature in the super-cooled liquid region of the FMG particles, where the FMG particles act as a soft liquid-like binder, resulting in composites with low or zero porosity. The microstructure and mechanical properties of the composites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and compression test. The yield and fracture strength of the composites are 403 MPa and 660 MPa, respectively, while retaining a considerable fracture deformation of about 12%. The strengthening mechanism is associated with the grain refinement of the matrix and uniform distribution of the FMG particles

  6. CVD silicon carbide monofilament reinforced SrO-Al2O3-2SiO2 (SAS) glass-ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, N.P.

    1995-08-01

    Unidirectional CVD SiC fiber-reinforced SrO.Al2O3.2SiO2 (SAS) glass-ceramic matrix composites have been fabricated by hot pressing at various combinations of temperature, pressure and time. Both carbon-rich surface coated SCS-6 and uncoated SCS-0 fibers were used as reinforcements. Almost fully dense composites have been obtained. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase observed in the matrix from x-ray diffraction. During three point flexure testing of composites, a test span to thickness ratio of approximately 25 or greater was necessary to avoid sample delamination. Strong and tough SCS-6/SAS composites having a first matrix crack stress of approximately 300 MPa and an ultimate bend strength of approximately 825 MPa were fabricated. No chemical reaction between the SCS-6 fibers and the SAS matrix was observed after high temperature processing. The uncoated SCS-0 fiber-reinforced SAS composites showed only limited improvement in strength over SAS monolithic. The SCS-0/SAS composite having a fiber volume fraction of 0.24 and hot pressed at 1400 deg C exhibited a first matrix cracking stress of approximately 231 +/- 20 MPa and ultimate strength of 265 +/- 17 MPa. From fiber push-out tests, the fiber/matrix interfacial debonding strength (tau(sub debond)) and frictional sliding stress (tau(sub friction)) in the SCS-6/SAS system were evaluated to be approximately 6.7 +/- 2.3 MPa and 4.3 +/- 0.6 MPa, respectively, indicating a weak interface. However, for the SCS-0/SAS composite, much higher values of approximately 17.5 +/- 2.7 MPa for tau(sub debond) and 11.3 +/- 1.6 MPa for tau(sub friction) respectively, were observed; some of the fibers were so strongly bonded to the matrix that they could not be pushed out. Examination of fracture surfaces revealed limited short pull-out length of SCS-0 fibers.

  7. CVD silicon carbide monofilament reinforced SrO-Al2O3-2SiO2 (SAS) glass-ceramic composites

    Science.gov (United States)

    Bansal, Narottam P.

    1995-01-01

    Unidirectional CVD SiC fiber-reinforced SrO.Al2O3.2SiO2 (SAS) glass-ceramic matrix composites have been fabricated by hot pressing at various combinations of temperature, pressure and time. Both carbon-rich surface coated SCS-6 and uncoated SCS-0 fibers were used as reinforcements. Almost fully dense composites have been obtained. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase observed in the matrix from x-ray diffraction. During three point flexure testing of composites, a test span to thickness ratio of approximately 25 or greater was necessary to avoid sample delamination. Strong and tough SCS-6/SAS composites having a first matrix crack stress of approximately 300 MPa and an ultimate bend strength of approximately 825 MPa were fabricated. No chemical reaction between the SCS-6 fibers and the SAS matrix was observed after high temperature processing. The uncoated SCS-0 fiber-reinforced SAS composites showed only limited improvement in strength over SAS monolithic. The SCS-0/SAS composite having a fiber volume fraction of 0.24 and hot pressed at 1400 deg C exhibited a first matrix cracking stress of approximately 231 +/- 20 MPa and ultimate strength of 265 +/- 17 MPa. From fiber push-out tests, the fiber/matrix interfacial debonding strength (tau(sub debond)) and frictional sliding stress (tau(sub friction)) in the SCS-6/SAS system were evaluated to be approximately 6.7 +/- 2.3 MPa and 4.3 +/- 0.6 MPa, respectively, indicating a weak interface. However, for the SCS-0/SAS composite, much higher values of approximately 17.5 +/- 2.7 MPa for tau(sub debond) and 11.3 +/- 1.6 MPa for tau(sub friction) respectively, were observed; some of the fibers were so strongly bonded to the matrix that they could not be pushed out. Examination of fracture surfaces revealed limited short pull-out length of SCS-0 fibers. The applicability of various micromechanical models for predicting the values of first matrix cracking stress and ultimate strength of these

  8. Effect of Nano-SiC Particles on the Performance and Microstructure of Si3N4/SiC Composite Ceramics%纳米SiC对Si3N4/SiC复相陶瓷性能及显微结构的影响

    Institute of Scientific and Technical Information of China (English)

    张伟儒; 李勇; 陈文

    2007-01-01

    In this paper, Si3 N4/SiC composite ceramics were prepared from two different raw materials with nano-SiC particles or organic precursor. Effect of nano-SiC particles on the performance and microstructure of the Si3 N4/SiC ceramics was studied, and the relation between reinforced mechanism and microstructure of materials was also investigated.%本研究通过采用纳米SiC粉体及有机前驱体两种途径,制备了Si3N4/SiC粒子(Si3 N4/纳米SiC)复相陶瓷,研究了纳米SiC对Si3 N4/SiC复相陶瓷性能及显微结构的影响,讨论了材料强化的机制与显微结构的关系.

  9. Effects of Fiber Content on Mechanical Properties of CVD SiC Fiber-Reinforced Strontium Aluminosilicate Glass-Ceramic Composites

    Science.gov (United States)

    Bansal, Narottam P.

    1996-01-01

    Unidirectional CVD SiC(f)(SCS-6) fiber-reinforced strontium aluminosilicate (SAS) glass-ceramic matrix composites containing various volume fractions, approximately 16 to 40 volume %, of fibers were fabricated by hot pressing at 1400 C for 2 h under 27.6 MPa. Monoclinic celsian, SrAl2Si2O8, was the only crystalline phase formed, with complete absence of the undesired hexacelsian phase, in the matrix. Room temperature mechanical properties were measured in 3-point flexure. The matrix microcracking stress and the ultimate strength increased with increase in fiber volume fraction, reached maximum values for V(sub f) approximately equal to 0.35, and degraded at higher fiber loadings. This degradation in mechanical properties is related to the change in failure mode, from tensile at lower V(sub f) to interlaminar shear at higher fiber contents. The extent of fiber loading did not have noticeable effect on either fiber-matrix debonding stress, or frictional sliding stress at the interface. The applicability of micromechanical models in predicting the mechanical properties of the composites was also examined. The currently available theoretical models do not appear to be useful in predicting the values of the first matrix cracking stress, and the ultimate strength of the SCS-6/SAS composites.

  10. Fabrication of an r-Al2Ti intermetallic matrix composite reinforced with α-Al2O3 ceramic by discontinuous mechanical milling for thermite reaction

    Science.gov (United States)

    Mosleh, A.; Ehteshamzadeh, M.; Taherzadeh Mousavian, R.

    2014-10-01

    In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite (IMC) reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling (DMM) instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TiAl as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.

  11. Fabrication of an r-Al2Ti intermetallic matrix composite reinforced withα-Al2O3 ceramic by discontinuous mechanical milling for thermite reaction

    Institute of Scientific and Technical Information of China (English)

    A.Mosleh; M.Ehteshamzadeh; R.Taherzadeh Mousavian

    2014-01-01

    In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite (IMC) reinforced withα-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling (DMM) instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks forγ-TiAl as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.

  12. Use of the Materials Genome Initiative (MGI approach in the design of improved-performance fiber-reinforced SiC/SiC ceramic-matrix composites (CMCs

    Directory of Open Access Journals (Sweden)

    Mica Grujicic

    2016-07-01

    Full Text Available New materials are traditionally developed using costly and time-consuming trial-and-error experimental efforts. This is followed by an even lengthier material-certification process. Consequently, it takes 10 to 20 years before a newly-discovered material is commercially employed. An alternative approach to the development of new materials is the so-called materials-by-design approach within which a material is treated as a complex hierarchical system, and its design and optimization is carried out by employing computer-aided engineering analyses, predictive tools and available material databases. In the present work, the materials-by-design approach is utilized to design a grade of fiber-reinforced (FR SiC/SiC ceramic matrix composites (CMCs, the type of materials which are currently being used in stationary components, and are considered for use in rotating components, of the hot sections of gas-turbine engines. Towards that end, a number of mathematical functions and numerical models are developed which relate CMC constituents’ (fibers, fiber coating and matrix microstructure and their properties to the properties and performance of the CMC as a whole. To validate the newly-developed materials-by-design approach, comparisons are made between experimentally measured and computationally predicted selected CMC mechanical properties. Then an optimization procedure is employed to determine the chemical makeup and processing routes for the CMC constituents so that the selected mechanical properties of the CMCs are increased to a preset target level.

  13. 3-d analysis and verification of fracture growth mechanisms in fiber-reinforced ceramic composites. Final report, 1 April-31 December 1992

    Energy Technology Data Exchange (ETDEWEB)

    Cleary, M.P.; Keat, W.D.; Larson, M.C.; Patterson, F.T.

    1992-12-31

    This final report documents a 3-D computational and experimental investigation into the mechanics of roughening a brittle matrix by incorporating long brittle fibers. Computationally, small scale failure mechanisms ahead of a crack are explicitly modeled and merged with a continuum representation of the far field outside the process zone. Particular attention is given to the interfacial decohesion and frictional slipping near the tip of a matrix crack which is impinging upon an inclusion. The surface integral and finite element (SIFEH) method, which employs the principle of superposition to combine the best features of two powerful numerical techniques, provides an extremely flexible and efficient computational platform for modeling linear elastic fractures near material inhomogeneities. Applications to general 3-D fracture growth in multimaterial media demonstrate the capabilities of the computational technique and are also described. The computational simulation is being guided by laboratory experiments. Crack growth observations made on a model (micro-) structure comprising a glass rod embedded in a cement matrix show the toughening mechanisms of crack pinning and crack bridging in operation. In a second experiment, interfacial slip evolution was modeled experimentally for planar bimaterial interfaces. This combined experimental and numerical program has provided insight into optimal combinations of the key parameters (e.g. residual stresses at interface, friction coefficient, strength of fibers) to maximize toughness....Fracture mechanics, Fiber-reinforced composites, Ceramic composite materials, Surface-integral methods.

  14. Synthesis of HAP nano rods and processing of nano-size ceramic reinforced poly(L)lactic acid composites

    Science.gov (United States)

    Flanigan, Kyle Yusef

    2000-09-01

    Bone is unique among the various connective tissues in that it is a composite of organic and inorganic components. Calcium phosphates occur principally in the form of hydroxyapatite crystals {Ca10(PO4) 6(OH)2}. Secreted apatite crystals are integral to the structural rigidity of the bone. When a bone breaks, there is often a need to implant an orthotic device to support the broken bone during remodeling. Current technologies use either metal pins and screws that need to be removed (by surgery) once the healing is complete or polymeric materials that either get resorbed or are porous enough to allow bone ingrowth. Poly(L)Lactic acid and copolymers of polyglycolic acid (PGA) are thermoplastics which show promise as the matrix material in biosorbable/load bearing implants. In service this material is hydrolyzed generating water and L-lactate. Orthoses composed of neat PLLA resins require greater than three years for complete resorbtion, however; 95% of strength is lost in 2 to 3 weeks in-vitro. This has limited the deployment of load bearing PLLA to screws, pins or short bracing spans. There exists a need for the development of an implantable and biosorbable orthotic device which will retain its structural integrity long enough for remodeling and healing process to generate new bone material, about 10 weeks. The scope of this dissertation is the development of HAP nano-whisker reinforcement and a HAP/PLLA thermoplastic composite. As proof of the feasibility of generating nano-reinforcement PLLA-composites, the surface of a galleried clay, montmorillonite, was modified and clay/PLLA composites processed and then characterized. Hydroxyapatite nano-whiskers were synthesized and functionalized using organosilanes and Menhaden fish-oil (common organic dispersant). The functionalized nano-fibers were used to process HAP/PLLA composites. Characterization techniques included thermal analysis, magnetic spectroscopy, XRD and ICP analysis and electron microscopy. The

  15. Wear Characteristics of Hybrid Composites Based on Za27 Alloy Reinforced With Silicon Carbide and Graphite Particles

    Directory of Open Access Journals (Sweden)

    S. Mitrović

    2014-06-01

    Full Text Available The paper presents the wear characteristics of a hybrid composite based on zinc-aluminium ZA27 alloy, reinforced with silicon-carbide and graphite particles. The tested sample contains 5 vol.% of SiC and 3 vol.% Gr particles. Compocasting technique has been used to prepare the samples. The experiments were performed on a “block-on-disc” tribometer under conditions of dry sliding. The wear volumes of the alloy and the composite were determined by varying the normal loads and sliding speeds. The paper contains the procedure for preparation of sample composites and microstructure of the composite material and the base ZA27 alloy. The wear surface of the composite material was examined using the scanning electronic microscope (SEM and energy dispersive spectrometry (EDS. Conclusions were obtained based on the observed impact of the sliding speed, normal load and sliding distance on tribological behaviour of the observed composite.

  16. Spherically shaped micron-size particle-reinforced PMMA and PC composites for improving energy absorption capability

    Science.gov (United States)

    Kim, Hyung-ick; Kang, Eung-Chun; Jang, Jae-Soon; Suhr, Jonghwan

    2011-04-01

    The focus of this study was to experimentally investigate spherically shaped micron-size particles reinforced polymethyl methacrylate (PMMA) and polycarbonate (PC) polymer composites for improving energy absorbing capabilities such as toughness and low-velocity impact resistance. In this study, a solution mixing method was developed to fabricate both PMMA and PC polymer composites with spherically shaped micron-size polyamide- nylon 6 (PA6) particles inclusions. The morphology of the fracture surfaces of polymer composites was examined by using optical microscopy and scanning electron microscopy. Strain-rate dependent response of both PMMA and PC polymer composites was investigated by characterizing tensile and flexural properties. Low-velocity penetration testing was performed for both polymer composites and the key results observed for energy absorption capabilities are discussed in this study.

  17. Microstructural study and densification analysis of hot work tool steel matrix composites reinforced with TiB2 particles

    International Nuclear Information System (INIS)

    Hot work tool steels are characterized by good toughness and high hot hardness but are less wear resistant than other tooling materials, such as high speed steel. Metal matrix composites show improved tribological behavior, but not much work has been done in the field of hot work tool steels. In this paper TiB2-reinforced hot work tool steel matrix composites were produced by spark plasma sintering (SPS). Mechanical alloying (MA) was proposed as a suited process to improve the composite microstructure. Density measurements and microstructure confirmed that MA promotes sintering and produces a fine and homogeneous dispersion of reinforcing particles. X-ray diffraction patterns of the sintered composites highlighted the formation of equilibrium Fe2B and TiC, as predicted by thermodynamic calculations using Thermo-Calc® software. Scanning electron microscopy as well as scanning Kelvin probe force microscopy highlighted the reaction of the steel matrix with TiB2 particles, showing the formation of a reaction layer at the TiB2-steel interface. Phase investigations pointed out that TiB2 is not chemically stable in steel matrix because of the presence of carbon even during short time SPS. - Highlights: • TiB2 reinforced steel matrix composites were produced by spark plasma sintering. • TiB2 was successfully dispersed in the steel matrix by mechanical alloying. • Steel and TiB2 react during sintering forming equilibrium Fe2B and TiC. • The new phases were investigated by means of AFM, Volta potential and XRD analyses

  18. Microstructural study and densification analysis of hot work tool steel matrix composites reinforced with TiB{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Fedrizzi, A., E-mail: anna.fedrizzi@ing.unitn.it [Department of Industrial Engineering, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Pellizzari, M. [Department of Industrial Engineering, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Zadra, M. [K4Sint, Start-up of the University of Trento, Viale Dante 300, 38057 Pergine Valsugana (Italy); Marin, E. [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100 Udine (Italy)

    2013-12-15

    Hot work tool steels are characterized by good toughness and high hot hardness but are less wear resistant than other tooling materials, such as high speed steel. Metal matrix composites show improved tribological behavior, but not much work has been done in the field of hot work tool steels. In this paper TiB{sub 2}-reinforced hot work tool steel matrix composites were produced by spark plasma sintering (SPS). Mechanical alloying (MA) was proposed as a suited process to improve the composite microstructure. Density measurements and microstructure confirmed that MA promotes sintering and produces a fine and homogeneous dispersion of reinforcing particles. X-ray diffraction patterns of the sintered composites highlighted the formation of equilibrium Fe{sub 2}B and TiC, as predicted by thermodynamic calculations using Thermo-Calc® software. Scanning electron microscopy as well as scanning Kelvin probe force microscopy highlighted the reaction of the steel matrix with TiB{sub 2} particles, showing the formation of a reaction layer at the TiB{sub 2}-steel interface. Phase investigations pointed out that TiB{sub 2} is not chemically stable in steel matrix because of the presence of carbon even during short time SPS. - Highlights: • TiB{sub 2} reinforced steel matrix composites were produced by spark plasma sintering. • TiB{sub 2} was successfully dispersed in the steel matrix by mechanical alloying. • Steel and TiB{sub 2} react during sintering forming equilibrium Fe{sub 2}B and TiC. • The new phases were investigated by means of AFM, Volta potential and XRD analyses.

  19. Microstructure and compressive properties of in situ synthesized Ti-Si alloy composites reinforced with La2O3 particles

    International Nuclear Information System (INIS)

    The Ti-5.5Si alloy composites reinforced by La2O3 particles were prepared through the synthesis reaction from Ti, Si, La and SiO2 with non-consumable vacuum arc melting. The microstructures were examined by means of optical microscopy (OM), backscattered scanning electron microscopy (SEM). The phase analysis was identified by X-ray diffraction (XRD). There are four phases in the composite, namely Ti5Si3, La2O3, α-Ti and β-Ti. In the microstructures of those composites, the continuous and quasi-continuous network-shape Ti5Si3 + Ti eutectic cell abundantly exists, and the La2O3 reinforcement grows from near-equiaxed shape to dendritic shape with increase of La content. The compressive properties of the as-cast composites were tested with strain rate 1 mm/min at room temperature. The results showed that the introduction of in situ La2O3 particles can significantly improve the compressive strength and the Young's modulus of Ti-5.5Si alloy.

  20. Particle Board and Oriented Strand Board Prepared with Nanocellulose-Reinforced Adhesive

    OpenAIRE

    Stefan Veigel; Jörn Rathke; Martin Weigl; Wolfgang Gindl-Altmutter

    2012-01-01

    Adhesives on the basis of urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF) are extensively used in the production of wood-based panels. In the present study, the attempt was made to improve the mechanical board properties by reinforcing these adhesives with cellulose nanofibers (CNFs). The latter were produced from dissolving grade beech pulp by a mechanical homogenization process. Adhesive mixtures with a CNF content of 0, 1, and 3 wt% based on solid resin were prepared by mixing ...

  1. Numerical Simulation of Dynamic Response of Fiber Reinforced Ceramic Matrix Composite Beam with Matrix Cracks Using Multiscale Modeling

    Institute of Scientific and Technical Information of China (English)

    Gao Xiguang; Song Yingdong; Sun Zhigang; Hu Xuteng

    2010-01-01

    A multiscale method for simulating the dynamic response of ceramic matrix composite (CMC) with matrix cracks is developed.At the global level,the finite element method is employed to simulate the dynamic response ofa CMC beam.While at the local level,the multiscale mechanical method is used to estimate the stress/strain response of the material.A distributed computing system is developed to speed up the simulation.The simulation of dynamic response of a Nicalon/CAS-Ⅱ beam being subjected to harmonic loading is performed as a numerical example.The results show that both the stress/strain responses under tension and compressive loading are nonlinear.These conditions result in a different response compared with that of elastic beam,such as:1) the displacement response is not symmetric about the axis of time;2) in the condition of small external load,the response at first order natural frequency is limited within a finite range;3) decreasing the matrix crack space will increase the displacement response of the beam.

  2. Development of ceramic-coated lithium particles for tritium production tests in high temperature engineering test reactor

    International Nuclear Information System (INIS)

    Ceramic-coated lithium particles (CCLP) are proposed for the tritium production tests in High Temperature Engineering Test Reactor (HTTR). The CCLP-production method and its tritium-retention as well as -release capability are mainly studied. The CCLP consists of a lithium compound kernel coated with ceramic layers. The kernel is made from lithium compound like LiAlO2. Ceramic materials like Al2O3 are used for the coating layers. The present study has made clear that tritium leakage from CCLP is less than 1% after 400-days-heating at 1,000K, and the tritium can be released completely in a short time by heating over 1,400K. From these characteristics, it is expected that the tritium can be well extracted from the CCLP by heating over 1,400K in the post irradiation test after irradiation under 1,000K in the HTTR. Furthermore, a good chemical stability between the kernel and coatings was confirmed through X-ray diffraction tests after heating of their powders. The mechanical integrity of coating layers for inner gas pressure in the CCLP was evaluated to be good on the basis of material data. (author)

  3. Effect of particle size on the in vitro bioactivity, hydrophilicity and mechanical properties of bioactive glass-reinforced polycaprolactone composites

    Energy Technology Data Exchange (ETDEWEB)

    Tamjid, E. [Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Bagheri, R., E-mail: rezabagh@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Vossoughi, M. [Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Department of Chemical and Petroleum Engineering, Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Simchi, A., E-mail: simchi@sharif.edu [Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of)

    2011-10-10

    Polycaprolactone (PCL) composite films containing 5 wt.% bioactive glass (BG) particles of different sizes (6 {mu}m, 250 nm, < 100 nm) were prepared by solvent casting methods. The ultra-fine BG particles were prepared by high-energy mechanical milling of commercial 45S5 Bioglass (registered) particles. The characteristics of bioactive glass particles were studied by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD) methods. In vitro bioactivity of the PCL/BG composite films was evaluated through immersion in the simulated body fluid (SBF). The films were analyzed by FE-SEM, energy dispersive spectrometry (EDS), XRD, and atomic force microscopy (AFM). The mechanical properties of highly-porous PCL/BG composites were examined on cylindrical specimens under quasi-static compression load. It was found that partial crystallization of amorphous BG particles during a prolonged mechanical milling occurred and calcium silicate (CaSiO{sub 3}) and sodium calcium silicate (Na{sub 2}CaSiO{sub 4}) phases were formed. The introduction of submicron BG particles (250 nm) was shown to improve the bioactivity of PCL films. In contrast to BG microparticles, the submicron BG particles were distributed on the film surfaces, providing a high surface exposure to SBF with an improved nanotopography. A notable increase in the stiffness and elastic modulus of the composite was also obtained. As compared to submicron BG particles, lower bioactivity and elastic modulus were acquired for PCL/BG nanoparticles. It was also shown that in spite of high specific surface area of the nanoparticles, partial crystallization during mechanical milling and agglomeration of the nanoparticles during processing decrease the bioactivity, hydrophilicity and mechanical response of the BG-reinforced PCL composites. Highlights: {yields} The effect of Bioglass particle size on the in vitro bioactivity of

  4. Processing-microstructure-properties relationships in small-particle plasma-sprayed ceramic coatings

    Science.gov (United States)

    Mawdsley, Jennifer Renee

    The objective of this study was to determine processing-microstructure-properties relationships for small-particle plasma-sprayed (SPPS) ceramic coatings. Plasma-sprayed yttria partially-stabilized zirconia (YSZ) coatings, which are used to protect superalloys from heat and the environment in turbine engines, and plasma-sprayed alumina coatings, which are being investigated as a potential replacement for chrome in corrosion protection applications, were fabricated using SPPS technology and their microstructure and pertinent properties were examined. The properties of plasma-sprayed YSZ and alumina coatings were investigated with designed experiments. The parameters varied include power, spray distance, total plasma gas flow, percent hydrogen in the plasma gas, injector angle, injector offset and carrier gas flow. The variations in thermal diffusivity, thermal conductivity, elastic modulus, and hardness for the YSZ SPPS coatings were found to correlate to the variations in density, which were related to the processing variables. It was found that surface roughness was related to the amount of splashing and debris associated with the single splats. In four-point bending strain tolerance and fatigue tests, the SPPS YSZ coatings showed very little acoustic emission activity, except in the case of tensile fatigue of a coating without network cracks. Small angle X-ray scattering experiments revealed that SPPS YSZ coatings have significantly less submicron intersplat porosity than conventional plasma-sprayed coatings, and that the pore and microcrack scattering area decreases with heat treatment due to the sintering of microcracks and small pores. The SPPS alumina coatings were optimized to produce a coating with excellent corrosion protection capabilities. It was found that the hardest SPPS alumina coatings did not provide the best corrosion protection due to unique porosity defect structures associated with surface bumps in the coatings. The surface bumps were

  5. Pyrochlore free 0.67PMN-0.33PT ceramics prepared by particle-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Ruiqing; Li, Yan [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Gong, Shuwen [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059 (China); Liu, Yong [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Li, Guorong [The State Key Lab of High Performance Ceramics and Superfinemicrostructure, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); Xu, Zhijun, E-mail: zhjxu@lcu.edu.cn [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China)

    2012-08-20

    Highlights: Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders were obtained by two-step particle-coating method. Black-Right-Pointing-Pointer Mg-citric acid polymeric complex coatings avoid the formation of pyrochlore phase. Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders have been successfully prepared at 800 Degree-Sign C. Black-Right-Pointing-Pointer The PMN-PT ceramics sintered at 1150 Degree-Sign C exhibited excellent electrical properties. - Abstract: In present study, pyrochlore-free 0.67Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.33PbTiO{sub 3} (0.67PMN-0.33PT) powders and ceramics have been successfully prepared. Using oxides as raw materials, pyrochlore-free 0.67PMN-0.33PT powders were obtained by two-step particle-coating method. The XRD and EDS results confirmed that the Mg-citric acid polymeric complex coatings effectively prevent the direct contact between PbO and Nb{sub 2}O{sub 5} and thus avoid the formation of pyrochlore phase. The obtained pyrochlore-free 0.67PMN-0.33PT powders at 800 Degree-Sign C showed uniform and even grain size. The 0.67PMN-0.33PT ceramics sintered at 1150 Degree-Sign C for 2 h exhibited 99% of relative density and a piezoelectric coefficient (d{sub 33}) of 576pC/N, a remnant polarization (P{sub r}) of 28.4 {mu}C/cm{sup 2}, a planar electromechanical coupling factor (k{sub p}) of 0.55 and a mechanical quality factor (Q{sub m}) of 90.

  6. Fabrication and characterization of hybrid structured Al alloy matrix composites reinforced by high volume fraction of B4C particles

    International Nuclear Information System (INIS)

    In the present paper, hybrid structured B4C particles reinforced Al2024 matrix composites were prepared by the powder metallurgy method. The composites made from 100% mechanical milled composite powders have fracture strength of 670 MPa. With the addition of un-milled Al2024 powder increased from 10 vol% to 40 vol%, the room temperature compression strength decreased from 1115 MPa to 739 MPa, without any visible plastic deformation. However, when the fraction of un-milled Al2024 powder increased to 50 vol%, the compression strength was decreased to 580 MPa, while retaining a remarkable fracture strain up to 10%. The microstructures of the composites with different composition were examined by a scanning electron microscope and a transmission electron microscope. The contribution from different strengthening mechanisms was discussed. The hybrid structures are proved to account for the dramatic change of the fracture mechanism of the composites

  7. Microstructures and properties of rare earth-particles reinforced MoSi2 composites

    International Nuclear Information System (INIS)

    MoSi2 and rare earth (RE)/MoSi2 composites were synthesized by mechanical alloying (MA) and self-propagating high-temperature synthesis (SHS) techniques. Their properties of hot pressing disks were measured, such as hardness and fracture toughness at ambient temperature and compressive yield strength at elevated temperature. The responded microstructures were observed by using SEM and x-ray. the results show that the room temperature properties of MoSi2 matrix are obviously reinforced by addition of rare earth element (especially, when it is of 0.9 wt.%). The toughening mechanism in RE/MoSi2 composite include fine-grained, microcrack, crack deflection, crack microbridging, crack bowing and branching, and the strengthening mechanism is fine-grained. But RE/MoSi2 composites only synthesized by SHS have higher yield strength at elevated temperature, with grain-coarsened and dispersion strengthening mechanisms. (author)

  8. Effect of particle concentration on the structure and tribological properties of submicron particle SiC reinforced Ni metal matrix composite (MMC) coatings produced by electrodeposition

    Science.gov (United States)

    Gül, H.; Kılıç, F.; Uysal, M.; Aslan, S.; Alp, A.; Akbulut, H.

    2012-03-01

    In the present work, a nickel sulfate bath containing SiC submicron particles between 100 and 1000 nm was used as the plating electrolyte. The aim of this work is to obtain Ni-SiC metal matrix composites (MMCs) reinforced with submicron particles on steel surfaces with high hardness and wear resistance for using in anti-wear applications such as dies, tools and working parts for automobiles and vehicles. The influence of the SiC content in the electrolyte on particle distribution, microhardness and wear resistance of nano-composite coatings was studied. During the electroplating process, the proper stirring speed was also determined for sub-micron SiC deposition with Ni matrix. The Ni films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The depositions were controlled to obtain a specific thickness (between 50 and 200 μm) and volume fraction of the particles in the matrix (between 0.02 and 0.10). The hardness of the coatings was measured to be 280-571 HV depending on the particle volume in the Ni matrix. The tribological behaviors of the electrodeposited SiC nanocomposite coatings sliding against an M50 steel ball (Ø 10 mm) were examined on a tribometer. All the friction and wear tests were performed without lubrication at room temperature and in the ambient air (with a relative humidity of 55-65%). The results showed that the wear resistance of the nanocomposites was approximately 2-2.2 times more than those of unreinforced Ni.

  9. The Microstructure-Processing-Property Relationships in an Al Matrix Composite System Reinforced by Al-Cu-Fe Alloy Particles

    Energy Technology Data Exchange (ETDEWEB)

    Fei Tang

    2004-12-19

    Metal matrix composites (MMC), especially Al matrix composites, received a lot of attention during many years of research because of their promise for the development of automotive and aerospace materials with improved properties and performance, such as lighter weight and better structural properties, improved thermal conductivity and wear resistance. In order to make the MMC materials more viable in various applications, current research efforts on the MMCs should continue to focus on two important aspects, including improving the properties of MMCs and finding more economical techniques to produce MMCs. Solid state vacuum sintering was studied in tap densified Al powder and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed Al and Al alloy powders for solid state sintering, which may lead to simplification of current Al powder consolidation processing methods. Elemental Al-based composites reinforced with spherical Al-Cu-Fe alloy powders were produced by quasi-isostatic forging and vacuum hot pressing (VHP) consolidation methods. Microstructures and tensile properties of AYAl-Cu-Fe composites were characterized. It was proved that spherical Al-Cu-Fe alloy powders can serve as an effective reinforcement particulate for elemental Al-based composites, because of their high hardness and a preferred type of matrix/reinforcement interfacial bonding, with reduced strain concentration around the particles. Ultimate tensile strength and yield strength of the composites were increased over the corresponding Al matrix values, far beyond typical observations. This remarkable strengthening was achieved without precipitation hardening and without severe strain hardening during consolidation because of

  10. Novel titanium particles reinforced Zr-based bulk metallic glass composites prepared by infiltration casting

    Institute of Scientific and Technical Information of China (English)

    Cuimei Zhang; Xidong Hui; Meiling Wang; Guoliang Chen

    2008-01-01

    A novel Ti/Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 composite was successfully prepared by infiltrating the melt into sintered Ti preform. It shows that the introduction of Ti particles into the composite results in an increase in elastic strain to 3% and an enhancement of the strength up to 2.1 GPa. High specific strength has been obtained because of the decrease in density of the composite. It is suggested that an improvement in the mechanical properties of the composite may be attributed to the generation of multiple shear bands and some deformation in the Ti particles.

  11. Improving the ballistic performance of ultra high molecular weight polyethylene fiber reinforced composites using conch particles

    International Nuclear Information System (INIS)

    A new method was proposed to improve ballistic impact performance of unidirectional ultra high molecular weight polyethylene (UHMWPE) fiber plate (UD plate) by adding shell particles in matrix. The complex micro-laminate structure of these bio-composite materials was studied. It was revealed by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) spectra that modified shell particles were uniformly dispersed in the matrix. The results of ballistic tests and temperature adaptation tests demonstrated that the bulletproof property of the modified UD plate was improved by 20%.

  12. Preparation and characterization of TiC particulate locally reinforced steel matrix composites from Cu–Ti–C system with various C particles

    OpenAIRE

    Yunhong Liang; Qian Zhao; Zhihui Zhang; Xiujuan Li; Luquan Ren

    2014-01-01

    The fabrication of steel-matrix composites locally reinforced with TiC particulates by the self-propagating high-temperature synthesis (SHS) reactions in the 20 wt.% Cu–Ti–C system with various C particle sizes during casting has been investigated, respectively. The composites synthesized with ∼1 μm and ∼38 μm C particles consist of TiC, Cu and γ-Fe phases, while the one synthesized with ∼150 μm C particle mainly consists of TiC, Cu, γ-Fe and Fe2Ti phases. With the increase in the C particle ...

  13. CROWDED HYBRID PANEL MANUFACTURED WITH PEANUT HULLS REINFORCED WITH ITAÚBA WOOD PARTICLES

    Directory of Open Access Journals (Sweden)

    Guilherme Barbirato

    2014-09-01

    Full Text Available http://dx.doi.org/10.5902/1980509815726In this paper, it was considered the study of the potential use of peanut hulls and wood particles of itaúba (Mezilaurus itauba species in order to add value to these materials through the manufacture of hybrid particle board in order to compare the physical and mechanical performances as well as durability. For these procedures, it was used the bi-component polyurethane resin based on castor beans (mammon oil and urea-formaldehyde. The product quality was evaluated based on the requirements of the standards NBR 14.810:2006 APA PRP and 108, through physico-mechanical and microstructural durability. The results indicate that the incorporation of wood particles warrants an increase in physical-mechanical properties of the particleboard manufactured with peanut hulls, the polyurethane resin based on castor oil was effective as a particle adhesive binder and the durability assay indicated that the material should be used under conditions of low exposure to moisture.

  14. Tungsten particle reinforced Al 5083 composite with high strength and ductility

    Energy Technology Data Exchange (ETDEWEB)

    Bauri, Ranjit, E-mail: rbauri@iitm.acin; Yadav, Devinder; Shyam Kumar, C.N.; Balaji, B.

    2015-01-03

    Tungsten particles were incorporated into an Al 5083 matrix by friction stir processing (FSP). FSP resulted in uniform dispersion of the tungsten particles with excellent interfacial bonding and more importantly without the formation of any harmful intermetallics. For the first time, the particles penetrated to a depth equal to the full pin length of the tool. A novel aspect of the 5083 Al–W composite is that it showed an improvement of more than 100 MPa in the UTS and at the same time exhibited a high ductility (30%). The ductility was also evident from the well defined dimples in the fracture surface which also revealed the superior bonding between the particles and the matrix. FSP also resulted in substantial grain refinement of the Al matrix. Electron backscatter diffraction (EBSD) and transmission electron microscopy analysis revealed that the fine grains formed by dynamic recrystallization. A gradual transformation from sub-grain to high-angle grain boundaries was observed from EBSD analysis pointing towards the occurrence of a continuous type of dynamic recrystallization process.

  15. Tungsten particle reinforced Al 5083 composite with high strength and ductility

    International Nuclear Information System (INIS)

    Tungsten particles were incorporated into an Al 5083 matrix by friction stir processing (FSP). FSP resulted in uniform dispersion of the tungsten particles with excellent interfacial bonding and more importantly without the formation of any harmful intermetallics. For the first time, the particles penetrated to a depth equal to the full pin length of the tool. A novel aspect of the 5083 Al–W composite is that it showed an improvement of more than 100 MPa in the UTS and at the same time exhibited a high ductility (30%). The ductility was also evident from the well defined dimples in the fracture surface which also revealed the superior bonding between the particles and the matrix. FSP also resulted in substantial grain refinement of the Al matrix. Electron backscatter diffraction (EBSD) and transmission electron microscopy analysis revealed that the fine grains formed by dynamic recrystallization. A gradual transformation from sub-grain to high-angle grain boundaries was observed from EBSD analysis pointing towards the occurrence of a continuous type of dynamic recrystallization process

  16. Synthesis and Characterization of SiC Reinforced HE-30 Al Alloy Particulate MMCs

    OpenAIRE

    Pradyumna Phutane; VijayKumar S. Jatti; Ravi Sekhar; Singh, T.P.

    2013-01-01

    Metal matrix composites have evoked a keen interest in recent times for potential applications in many areas, especially aerospace & automotive industries owing to their superior strength to weight ratio. A particle reinforced metal matrix composite consists of uniform distribution of strengthening ceramic particles embedded within metal matrix. Manufacturing of aluminum alloy based composites via stir casting is one of the prominent and economical routes for processing of metal matrix compos...

  17. Recovery and Modification of Waste Tire Particles and Their Use as Reinforcements of Concrete

    OpenAIRE

    Eduardo Sadot Herrera-Sosa; Gonzalo Martínez-Barrera; Carlos Barrera-Díaz; Epifanio Cruz-Zaragoza; Fernando Ureña-Núñez

    2015-01-01

    Environmental pollution caused by solid wastes is increasing in the last decades; one of these is referred to automotive tires, which are recycled by different methods, including mechanical grinding. One of the most recurrent applications is to use recycled particles as fillers in building materials, as hydraulic concrete. Nevertheless, detrimental values on the mechanical properties are obtained when they are added. For solving these problems, in this work, a novel proposal is to modify the ...

  18. Effect of the Addition MgO Nano Particle to Mechanical Properties and Microstructure of ZTA Ceramic Composite

    International Nuclear Information System (INIS)

    The mechanical properties and microstructure of zirconia-toughened alumina ceramic composite doped with nano particle of MgO is investigated. The nano-MgO weight percent was varied from 0 wt% to 1.3 wt%. Each batch of composition was mixed using ultrasonic cleaning and mechanical stirrer, uniaxially pressed and sintered at 1600 degree Celsius for 4 h in pressureless conditions. Analysis of bulk density, Vickers hardness, fracture toughness and microstructural observation has been carried out. Results of Vickers hardness increased linearly with addition of more nano-MgO until a certain composition. Maximum Vickers hardness obtained was 1740HV with 1.1 wt % MgO. (author)

  19. The Microstructure and Hardness Properties Analysis of Welded Aluminum Matrix Material Reinforced with SiC Using Different Currents and Forms of Welding

    Directory of Open Access Journals (Sweden)

    Arzum Ulukoy

    2015-12-01

    Full Text Available The welding of metal matrix material reinforced with ceramic particles has some problems such as formation of oxide layer, segregation occurring on welding area, and reaction of ceramic particles with welding bath. The expected mechanical properties cannot be obtained because of these problems. In this study, the weldability of aluminum 2014 alloy reinforced with SiC particles was investigated. MIG welding process was used via using AlSi5 alloy wire at different types and values of welding currents. Samples obtained using manual welding current were compared to those obtained using pulse welding current, in terms of microstructure and distribution of hardness. The effects of different types and values of welding currents on the microstructure and hardness distribution were examined. It was obtained that the welding of the composite with aluminum 2014 alloy matrix reinforced with SiC particles via using of pulse current, potential formation of segregation was prevented and microstructural properties were improved.

  20. Production and Characterization of Brass-matrix Composites Reinforced with Ni59Zr20Ti16Si2Sn3 Glassy Particles

    OpenAIRE

    Bum Sung Kim; Jürgen Eckert; Min Ha Lee; Sergio Scudino; Uta Kühn; Jin Young Kim

    2012-01-01

    Brass-matrix composites reinforced with 40 and 60 vol.% of Ni59Zr20Ti16Si2Sn3 glassy particles were produced by powder metallurgy. The crystallization behavior and the temperature dependence of the viscosity of the glass reinforcement were studied in detail to select the proper sintering parameters in order to avoid crystallization of the glassy phase during consolidation. The brass-glass powder mixtures were prepared through manual blending as well as by ball milling to analyze the effect of...

  1. ANL-1(A) - Development of nondestructive evaluation methods for structural ceramics

    International Nuclear Information System (INIS)

    This section includes the following papers: Development of Nondestructive Evaluation Methods for Structural Ceramics; Effects of Flaws on the Fracture Behavior of Structural Ceramics; Design, Fabrication, and Interface Characterization of Ceramic Fiber-Ceramic Matrix Composites; Development of Advanced Fiber-Reinforced Ceramics; Modeling of Fibrous Preforms for CVD Infiltration; NDT of Advanced Ceramic Composite Materials; Joining of Silicon Carbide Reinforced Ceramics; Superconducting Film Fabrication Research; Short Fiber Reinforced Structural Ceramics; Structural Reliability and Damage Tolerance of Ceramic Composites for High-Temperature Applications; Fabrication of Ceramic Fiber-Ceramic Matrix Composites by Chemical Vapor Infiltration; Characterization of Fiber-CVD Matrix interfacial Bonds; Microwave Sintering of Superconducting Ceramics; Improved Ceramic Composites Through Controlled Fiber-Matrix Interactions; Evaluation of Candidate Materials for Solid Oxide Fuel Cells; Ceramic Catalyst Materials: Hydrous Metal Oxide Ion-Exchange Supports for Coal Liquefaction; and Investigation of Properties and Performance of Ceramic Composite Components

  2. Comparative Evaluation of the Antibacterial Efficacy of Type II Glass lonomer Cement, Type IX Glass lonomer Cement, and AMALGOMER™ Ceramic Reinforcement by Modified “Direct Contact Test”: An in vitro Study

    Science.gov (United States)

    Assudani, Harsha G; Patil, Vidyavathi; Kukreja, Pratibha; Uppin, Chaitanya; Thakkar, Prachi

    2016-01-01

    ABSTRACT Background: Streptococcus mutans (ATCC25175) has a profound effect on the incidence of dental decay in the human population. Many studies have been performed to assess the antimicrobial activity of different cements. However, little or no information is available about the antibacterial properties of Type II glass ionomer cement (GIC), Type IX GIC, and AMALGOMER™ ceramic reinforcement (CR). Aim: To comparatively evaluate the antibacterial activity of Type II GIC, Type IX GIC, and AMALGOMER™ CR by modified direct contact test. Materials and methods: The total sample size was 72 which was divided into four study groups. Six wells were coated by each: Type II GIC, Type IX GIC, AMALGOMER™ CR, and control group (only S. mutans). Statistical analysis was done using analysis of variance and the intergroup comparison was done using post hoc Tukey test. Results: AMALGOMER™ CR was found to have a better antibacterial effect as compared with Type II and IX GIC. Conclusion: AMALGOMER™ CR can serve as a valuable cement in pediatric dentistry due to its anticariogenic property. How to cite this article: Hugar SM, Assudani HG, Patil V, Kukreja P, Uppin C, Thakkar P. Comparative Evaluation of the Antibacterial Efficacy of Type II Glass lonomer Cement, Type IX Glass Ionomer Cement, and AMALGOMER™ Ceramic Reinforcement by Modified “Direct Contact Test”: An in vitro Study. Int J Clin Pediatr Dent 2016;9(2):114-117. PMID:27365930

  3. 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.

  4. Investigation on the Effects of Titanium Diboride Particle Size on Radiation Shielding Properties of Titanium Diboride Reinforced Boron Carbide-Silicon Carbide Composites

    Directory of Open Access Journals (Sweden)

    A.O. Addemir

    2012-03-01

    Full Text Available Composite materials have wide application areas in industry. Boron Carbide is an important material for nuclear technology. Silicon carbide is a candidate material in the first wall and blankets of fusion power plants. Titanium diboride reinforced boron carbide-silicon carbide composites which were produced from different titanium diboride particle sizes and ratios were studied for searching of the behaviour against the gamma ray. Cs-137 gamma radioisotope was used as gamma source in the experiments which has a single gamma-peak at 0.662 MeV. Gamma transmission technique was used for the measurements. The effects of titanium diboride particle size on radiation attenuation of titanium diboride reinforced boron carbide-silicon carbide composites were evaluated in related with gamma transmission and the results of the experiments were interpreted and compared with each other. Composite materials have wide application areas in industry. Boron Carbide is an important material for nuclear technology. Silicon carbide is a candidate material in the first wall and blankets of fusion power plants. Titanium diboride reinforced boron carbide-silicon carbide composites which were produced from different titanium diboride particle sizes and ratios were studied for searching of the behaviour against the gamma ray. Cs-137 gamma radioisotope was used as gamma source in the experiments which has a single gamma-peak at 0.662 MeV. Gamma transmission technique was used for the measurements. The effects of titanium diboride particle size on radiation attenuation of titanium diboride reinforced boron carbide-silicon carbide composites were evaluated in related with gamma transmission and the results of the experiments were interpreted and compared with each other. Composite materials have wide application areas in industry. Boron Carbide is an important material for nuclear technology. Silicon carbide is a candidate material in the first wall and blankets of fusion

  5. A statistical analysis on erosion wear behaviour of A356 alloy reinforced with in situ formed TiB2 particles

    International Nuclear Information System (INIS)

    Solid particle erosion wear behaviour of A356 and A356/TiB2in situ composites has been studied. A356 alloy reinforced with in situ TiB2 particles was fabricated by the reaction of halide salts with aluminium melt and the formation of Al3Ti brittle phase is completely suppressed. The composites show good grain refinement of α-Al and modification of eutectic Si. These in situ composites show high hardness and better erosion resistance than the base alloy. Though the sizes of in situ formed TiB2 reinforcement particles are smaller than the erodent SiC particles, TiB2 particles are able to effectively resist the erodent particles. Design of experiment has been used to run the solid particle erosion experiment. An attempt has also been made to develop a mathematical model by using regression analysis. Analysis of variance (ANOVA) technique is applied to check the validity of the developed model. Student's t-test is utilized to find out the significance of factors. The wear mechanism has been studied by analyzing the surface of the worn specimen using scanning electron microscopy and energy dispersive X-ray microanalysis

  6. Effect of reinforcing particle type on morphology and age-hardening behavior of Al–4.5 wt.% Cu based nanocomposites synthesized through mechanical milling

    International Nuclear Information System (INIS)

    The effects of reinforcing particle type (SiC and TiC) on morphology and precipitation hardening behavior of Al–4.5%Cu based nanocomposites synthesized via mechanical milling were investigated in the current work. In order to study the microstructure and morphology of mechanically milled powder, X-ray diffraction technique, scanning electron microscopy and high resolution transmission electron microscopy were utilized. Results revealed that at the early stages of mechanical milling, when reinforcing particles are polycrystal, the alloying process is enhanced more in the case of using the TiC particles as reinforcement. But, at the final stages of mechanical milling, when reinforcing particles are single crystal, the alloying process is enhanced more in the case of using the SiC ones. Transmission electron microscopy results demonstrated that Al–4.5 wt.%Cu based nanocomposite powders were synthesized and confirmed that the mutual diffusion of aluminum and copper occurs through the interfacial plane of (200). The hardness results showed that not only does introducing 4 vol.% of reinforcing particles (SiC or TiC) considerably decrease the porosity of the bulk composite samples, but also it approximately doubles the hardness of Al–4.5 wt.%Cu alloy (53.4 HB). Finally, apart from TEM and scanning electron microscopy observation which are localized, a decline in hardness in the TiC and SiC contained samples, respectively, after 1.5 and 2 h aging time at 473 K proves the fact that the size of SiC particles is smaller than the size of the TiC ones. - Highlights: ► HRTEM results show mutual diffusion of Al and Cu occurs through the (200) planes. ► TiC particles enhance alloying process more than the SiC ones at the early stages of MM. ► SiC particles enhance alloying process more than the TiC ones at the final stages of MM

  7. Welding of SiC particle reinforced 6061 Al matrix composite with pulsed TIG

    Institute of Scientific and Technical Information of China (English)

    陈茂爱; 武传松; 高进强

    2002-01-01

    SiCp/6061Al alloy composite was welded by using TIG and pulsed-TIG welding (P-TIG) without addition of filler metal, or with addition of Al-Si or Al-Mg filler metal. The microstructure and properties of the weld were investigated with XRD, OM, TEM, and MTS-810 testing system was used to observe the effect of different welding procedure and filler metals on the microstructure and properties of the weld. Thermodynamic of SiC-Al reaction was used to analyze the tendency of the reaction between SiC particle and Al matrix during welding. The results showed that the P-TIG tends to produce less plate-like Al4C3 precipitates than TIG; when welding with P-TIG, addition of Al-Si filler metal can not only prevent from formation of Al4C3, but also decrease hot crack sensitivity of weld; the tensile strength of joint of adding Al-Si filler metal is higher than that of adding Al-Mg filler metal. The SiCp/6061Al composite can be successfully welded by P-TIG with addition of Al-Si filler metal.

  8. Hard magnetic composite materials with polymer matrix reinforced Nd-Fe-B hard magnetic particles

    International Nuclear Information System (INIS)

    Investigation results of the polymer matrix hard magnetic composite materials with particles of the powered rapid quenched Nd-Fe-B strip quenched Nd-Fe-B strip are presented at this paper. The Nd-Fe-B powder was doped (10 wt.%) with powder of iron, aluminium, CuSn10 casting copper alloy with tin, high alloy steel X2CrNiNo17-12-2 and aluminium oxide. Epoxy resin has been used as a matrix (2.5 wt.%). The pressure of 800-900 MPa and cured afterwards for 2 hours at 180 oC. The influence of dopes' materials kind on magnetic and mechanical composites were unilaterally and uniaxially pressed at room temperature under properties of composite materials was estimated. Metallographic examination of the composite materials' structure and XRD analysis has been made. Investigations of magnetic properties of composite materials show the influence of the addition material. It was estimated that dopes of soft magnetic material decrease coercive force HcB and slightly reduce remanence Br of composite. The addition of non-magnetic material decreases coercive force HcB and reduces remanence Br. Metallographic examination of the structure shows uniform distribution of Nd-Fe-B powder in the polymer matrix, grains are irregular elongated in the direction. Dopes distribution in a polymer matrix is irregular, agglomerations of powders of aluminium, iron and copper casting alloy with tin have noticed. Ultimate compressive strength of composite materials is improved for all the addition material, except powder of aluminium oxide. XRD analysis has identified the hard magnetic phase Nd2Fe14B. (author)

  9. Preparation and properties of CaO-Al2O3-SiO2 glass-ceramics by sintered frits particle from mining wastes

    Directory of Open Access Journals (Sweden)

    He F.

    2014-01-01

    Full Text Available The paper reports on some experimental results obtained from the production of glass-ceramics containing gold tailings powder (GTP. Frits particle sintered technology was used to prepare glass ceramic products. SiO2, CaO, ZnO, BaO and B2O3 were selected to adjust the composition of the glass. Based on the results of differential thermal analysis (DTA, the nucleation and crystallization temperature of parent glass samples with different schedule were identified, respectively. X-ray diffraction (XRD analysis of the produced glass-ceramics materials revealed that the main crystalline phase was β-wollastonite. With the increasing of CaO content, the intensity of crystal diffractive peaks also increases. The formation of β-wollastonite crystal could be accelerated by the increasing of CaO. The glass-ceramics with fine microstructure showed better physical, mechanical properties and chemical resistance. Overall results indicated that it was a feasible attempt to produce glass-ceramics for building and decorative materials from waste materials. The amount of GTP used in the glass batches was more than 65 wt% of the whole raw.

  10. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  11. Particle flow of ceramic breeder pebble beds in bi-axial compression experiments

    International Nuclear Information System (INIS)

    Pebble beds of Tritium breeding ceramic material are investigated within the framework of developing solid breeder blankets for future nuclear fusion power plants. For the thermo-mechanical characterisation of such pebble beds, bed compression experiments are the standard tools. New bi-axial compression experiments on 20 and 30 mm high pebble beds show pebble flow effects much more pronounced than in previous 10 mm beds. Owing to the greater bed height, conditions are reached where the bed fails in cross direction and unhindered flow of the pebbles occurs. The paper presents measurements for the orthosilicate and metatitanate breeder materials that are envisaged to be used in a solid breeder blanket. The data are compared with calculations made with a Drucker-Prager soil model within the finite-element code ABAQUS, calibrated with data from other experiments. It is investigated empirically whether internal bed friction angles can be determined from pebble beds of the considered heights, which would simplify, and broaden the data base for, the calibration of the Drucker-Prager pebble bed models

  12. The use of nano-particles to produce iridescent metallic effects on ancient ceramic objects.

    Science.gov (United States)

    Fermo, P; Padeletti, G

    2012-11-01

    Nano-sized materials have been often used in the past to realize objects with particular characteristics. One of the most outstanding examples is represented by luster pottery, showing shining surfaces with particular optical properties. Luster was one of the most sophisticated technique for the decoration of majolicas. It consists of a thin metallic film containing silver, copper and other substances, like iron oxide and cinnabar, applied in a reducing atmosphere on a previously glazed ceramic. In such a way, beautiful iridescent reflections of different colours (in particular gold and ruby-red) are obtained. This technique, at first developed in Iraq, was introduced in Italy from Spain. In Italy the potters of the two centres of Gubbio and Deruta, in central Italy, became so expert that nowadays modern artisans are not able to reproduce the wonderful effects obtained during Renaissance. A complete characterization by means of numerous techniques has been carried out on a great number of shards and precious work of arts conserved in many important museums. This allowed to draw some correlations between the preparation technique and the obtained nano-structure. PMID:23421282

  13. Growth mechanism, distribution characteristics and reinforcing behavior of (Ti, Nb)C particle in laser cladded Fe-based composite coating

    International Nuclear Information System (INIS)

    Highlights: • Reinforced (Ti, Nb)Cp can be synthesized in the molten pool during laser cladding. • Formation mechanism of (Ti, Nb)Cp are impacted by Ti/Nb atomic ratio. • Appropriate Ti element can improve the precipitation of carbide particle. • Excess Ti weakens this effect above-mentioned. • The wear resistance of the coating was improved when Ti/Nb = 1. - Abstract: Over the past decade, researchers have demonstrated much interest in laser cladded metal matrix composite coatings for its good wear resistance, corrosion resistance, and high temperature properties. In this paper, in-situ (Ti, Nb)C particle reinforced Fe-based composite coatings were produced by laser cladding. The effects of Ti/Nb(atomic ratio) in the cladding powder on the formation mechanism and distribution characteristics of multiple particle were investigated. The results showed that when Ti/Nb > 1, Ti had a stronger ability to bond with C compared with Nb. (Ti, Nb)C multiple particles with TiC core formed in the molten pool. With the decrease of Ti/Nb, core-shell structure disappeared, the structure of particle got close to that of NbC gradually. It is found that the amount, area ratio and distribution of the reinforced particle in the coating containing Ti and Nb elements were improved, compared with these in the coating containing equal Nb element. When Ti/Nb = 1, the effects above-mentioned is most prominent, and the wear resistance of the coating is promoted obviously

  14. Growth mechanism, distribution characteristics and reinforcing behavior of (Ti, Nb)C particle in laser cladded Fe-based composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qingtang, E-mail: liqingtang123@126.com; Lei, Yongping, E-mail: yplei@bjut.edu.cn; Fu, Hanguang

    2014-10-15

    Highlights: • Reinforced (Ti, Nb)Cp can be synthesized in the molten pool during laser cladding. • Formation mechanism of (Ti, Nb)Cp are impacted by Ti/Nb atomic ratio. • Appropriate Ti element can improve the precipitation of carbide particle. • Excess Ti weakens this effect above-mentioned. • The wear resistance of the coating was improved when Ti/Nb = 1. - Abstract: Over the past decade, researchers have demonstrated much interest in laser cladded metal matrix composite coatings for its good wear resistance, corrosion resistance, and high temperature properties. In this paper, in-situ (Ti, Nb)C particle reinforced Fe-based composite coatings were produced by laser cladding. The effects of Ti/Nb(atomic ratio) in the cladding powder on the formation mechanism and distribution characteristics of multiple particle were investigated. The results showed that when Ti/Nb > 1, Ti had a stronger ability to bond with C compared with Nb. (Ti, Nb)C multiple particles with TiC core formed in the molten pool. With the decrease of Ti/Nb, core-shell structure disappeared, the structure of particle got close to that of NbC gradually. It is found that the amount, area ratio and distribution of the reinforced particle in the coating containing Ti and Nb elements were improved, compared with these in the coating containing equal Nb element. When Ti/Nb = 1, the effects above-mentioned is most prominent, and the wear resistance of the coating is promoted obviously.

  15. Early stages of sliding wear behaviour of Al2O3 and SiC reinforced aluminium

    International Nuclear Information System (INIS)

    Al matrix composites reinforced by 10 vol.% Al2O3 and SiC particles were subjected to dry sliding tests against steel using a slider-on-cylinder tribometer. Damage mechanisms were 'micro-machining' of the steel carried out by ceramic particles, plastic deformation and oxidation of the metal matrix, as well as abrasion. The results were discussed on the basis of the third-body wear model. (orig.)

  16. Research on Heat Treatment Schedule of Leucite-reinforced Dental Glass Ceramics%白榴石增强的牙科玻璃陶瓷的热处理制度研究

    Institute of Scientific and Technical Information of China (English)

    李莺; 姜通; 郭瑞松

    2012-01-01

    本文研究了白榴石增强的牙科玻璃陶瓷的热处理制度对白榴石晶体的生成、玻璃陶瓷的耐腐蚀性和力学性能的影响,采用热分析、X射线衍射分析、力学性能表征及金相显微观察等方法对热处理后的牙科玻璃陶瓷进行测试和分析.热分析表明,玻璃陶瓷晶核的生成温度为760℃,晶核的成长温度为1010℃.试验采用阶梯式升温热处理制度,成功地在玻璃陶瓷中析出白榴石晶体,随着白榴石含量的增加,材料的力学性能也获得了提高,热处理后材料的三点弯曲强度为102.2 MPa,显微硬度为5.45 GPa,断裂韧性为2.41 MPa·m1/2,强度达到ISO6872牙科陶瓷材料的标准.%The effects of heat treatment schedule of leucite-reinforced dental glass ceramics on the formation of leucite crystals, corrosion resistance and mechanical properties were studied. The dental glass ceramics after heat treatment were analyzed by thermal analysis, X ray diffraction analysis, mechanical property characterization and metallographic examination. Thermal analysis showed that the temperature of nucleation and crystallization was about 760 ℃ and 1010 ℃ , respectively. Leucite crystals were successfully obtained from the glass by heat treatment with stepped heating system. The existence of leucite crystals improved the mechanical properties of the dental glass ceramics. The three-point bending strength was 102.2 MPa, microhardness reached 5.45 GPa and fracture toughness was 2. 41 MPa ·m1/2. The strength of leucited-reinforced dental glass ceramics met the ISO 6872 standard.

  17. Flight-vehicle materials, structures, and dynamics - Assessment and future directions. Vol. 3 - Ceramics and ceramic-matrix composites

    Science.gov (United States)

    Levine, Stanley R. (Editor)

    1992-01-01

    The present volume discusses ceramics and ceramic-matrix composites in prospective aerospace systems, monolithic ceramics, transformation-toughened and whisker-reinforced ceramic composites, glass-ceramic matrix composites, reaction-bonded Si3N4 and SiC composites, and chemical vapor-infiltrated composites. Also discussed are the sol-gel-processing of ceramic composites, the fabrication and properties of fiber-reinforced ceramic composites with directed metal oxidation, the fracture behavior of ceramic-matrix composites (CMCs), the fatigue of fiber-reinforced CMCs, creep and rupture of CMCs, structural design methodologies for ceramic-based materials systems, the joining of ceramics and CMCs, and carbon-carbon composites.

  18. Wear and Corrosion Resistance of Fe-Based Coatings Reinforced by TiC Particles for Application in Hydraulic Systems

    Science.gov (United States)

    Bobzin, K.; Öte, M.; Linke, T. F.; Malik, K. M.

    2016-01-01

    Thermally sprayed Fe-based coatings reinforced by TiC particles are a cost-effective alternative to carbide coatings such as WC/CoCr, Cr3C2/NiCr, and hard chrome coatings. They feature a good wear resistance and—with sufficient amount of alloying elements like Cr and Ni—also a high corrosion resistance. In hydraulic systems, the piston is usually coated with hard chrome coatings for protection against corrosion and wear. New water-based hydraulic fluids require an adaption of the coating system. In order to investigate the wear and corrosion resistance of Fe/TiC, a novel powder consisting of a FeCr27Ni18Mo3 matrix and 34 wt.% TiC was applied by HVOF and compared to reference samples made of WC/CoCr (HVAF) and hard chrome. Besides an in-depth coating characterization (metallographic analyses, electron microprobe analyzer-EMPA), wear resistance was tested under reverse sliding in a water-based hydraulic fluid. The novel Fe/TiC coatings showed good wear protection properties, which are comparable to conventional coatings like WC/CoCr (HVAF) and electroplated hard chrome coatings. Corrosion resistance was determined by polarization in application-oriented electrolytes (hydraulic fluid at 60 °C, artificial sea water at RT). The corrosion resistance of the investigated iron-based coatings at 60 °C was superior to the references coatings for both hydraulic fluids. Selected coatings were tested in an application-oriented hydraulic test bench with HFC hydraulic fluid (water polymer solutions) showing comparably good wear and corrosion resistance as the hard chrome-coated reference.

  19. Tribological properties of laser cladding TiB2 particles reinforced Ni-base alloy composite coatings on aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Long He; Ye-Fa Tan; Xiao-Long Wang; Qi-Feng Jing; Xiang Hong

    2015-01-01

    To improve the wear resistance of aluminum alloy frictional parts,TiB2 particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding.The microstructure and tribological properties of the composite coatings were investigated.The results show that the composite coating contains the phases of NiAl,Ni3Al,Al3Ni2,TiB2,TiB,TiC,CrB,and Cr23C6.Its microhardness is HV0.5 855.8,which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy.The friction coefficients of the composite coatings are reduced by 6.8 %-21.6 % and 13.2 %-32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys,while the wear losses are 27.4 %-43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %-32.7 % of those of the aluminum alloys at different loads.At the light loads ranging from 3 to 6 N,the calculated maximum contact stress is smaller than the elastic limit contact stress.The wear mechanism of the composite coatings is micro-cutting wear,but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress.As the loads increase to 12 N,the calculated flash temperature rises to 332.1 ℃.The composite coating experiences multi-plastic deformation wear,micro-brittle fracture wear,and oxidative wear.

  20. Experimental investigation of viscosity and thermal conductivity of suspensions containing nanosized ceramic particles

    Directory of Open Access Journals (Sweden)

    H.P. Schuchmann

    2008-12-01

    Full Text Available Purpose: In this study we report measurements of effective thermal conductivity by using 3ω methodand effective viscosity by vibro-viscometer for SiO2-water and Al2O3-water nanofluids at different particleconcentrations and temperatures.Design/methodology/approach: The effective thermal conductivity of nanofluids is measured by a techniquebased on a hot wire thermal probe with ac excitation and 3ω lock-in detection. There is presented an experimentalstudy of thermal conductivity and viscosity of nanofluids. It was investigated Alumina and Silica nanoparticles inwater with different particle concentrations.Findings: Measured results showed that the effective thermal conductivity of nanofluids increase as theconcentration of the particles increase but not anomalously as indicated in the majority of the literature and thisenhancement is very close to Hamilton-Crosser model, also this increase is independent of the temperature. Theeffective viscosities of these nanofluids increased by the increasing particle concentration and decrease by theincrease in temperature, and can not be predicted by Einstein model.Practical implications: The results show that for our samples, thermal conductivity values are inside the limitsof (moderately lower than Hamilton-Crosser model.Originality/value: Experiments at different temperatures show that relative thermal conductivity of nanofluidsis not related with the temperature of the fluid.

  1. Effect of Al2O3 Ceramic Particles on Corrosion Behaviour and Tribological Properties of Nickel Composite Coatings

    Directory of Open Access Journals (Sweden)

    Nowak M.

    2016-03-01

    Full Text Available The paper presents a study on corrosion behaviour and tribological properties of nickel composite coatings deposited by electrochemical method on aluminium alloy from 2xxx series (AlCu4MgSi. The nickel composite coatings were produced in a Watts bath of the following chemical composition: NiSO4·7H2O 150 g/l, NiCl2·6H2O 30 g/l, H3BO3 30 g/l with the addition of saccharin in an amount of 2 g/l. As hard ceramic dispersed particles embedded in the coating, alumina (Al2O3 was used in an amount of 12,5; 25; 50 and 75 g/l. Coatings were produced using cathodic current density of 6 A/dm2, bath temperature of 60°C, pH 4, and the time 60 minutes. The electroplating bath was stirred with a mechanical stirrer (350 rpm.

  2. Investigation on silver electric adhesive doped with Al{sub 2}O{sub 3} ceramic particles for sealing planar solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaoliang [Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China); Department of Applied Chemistry, Harbin Institute of Technology, No. 92 of West Dazhi Street, P.O. Box 211, Harbin 150001 (China); Sun, Kening; Le, Shiru; Zhang, Naiqing [Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); Department of Applied Chemistry, Harbin Institute of Technology, No. 92 of West Dazhi Street, P.O. Box 211, Harbin 150001 (China); Yan, Yan; Sun, Wang [Department of Applied Chemistry, Harbin Institute of Technology, No. 92 of West Dazhi Street, P.O. Box 211, Harbin 150001 (China); Wang, Peng [School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China)

    2009-07-15

    The silver electric adhesive doped with Al{sub 2}O{sub 3} ceramic particles is used as sealing material for planar solid oxide fuel cell (SOFC). The sealing temperature of this sealing material is 600 C with the heating rate of 2 C min{sup -1}, and the minimal leak rate ranges from 0.030 sccm cm{sup -1} to 0.040 sccm cm{sup -1}. When doping 15 mass% Al{sub 2}O{sub 3} ceramic particles into this sealing material, the thermal expansion coefficient of this material decreases from 20 ppm K{sup -1} to 15 ppm K{sup -1}, which improves the thermal matching performance and the long-term stability of the material significantly. When using the gradient sealing method with the pure silver electric adhesive and the silver electric adhesive doped with Al{sub 2}O{sub 3} ceramic particles to seal the interface of Ni-YSZ/SUS430 in the simulating cell, the minimal leak rate of 0.035 sccm cm{sup -1} is obtained for the cell. Furthermore, the simulating cell sealed with the compound silver electric adhesive presents good heat-resistant impact ability. Therefore, this compound sealing technique is a very promising sealing method for SOFC. (author)

  3. Improve Wear Resistance on Al 332 Alloy Matrix- Micro -Nano Al2O3 Particles Reinforced Composite

    Directory of Open Access Journals (Sweden)

    Rawnaq Ahmed Mohamed

    2014-03-01

    Full Text Available The wear behavior of alumina particulate reinforced A332 aluminium alloy composites produced by a stir casting process technique were investigated. A pin-on-disc type apparatus was employed for determining the sliding wear rate in composite samples at different grain size (1 µm, 12µm, 50 nm and different weight percentage (0.05-0.1-0.5-1 wt% of alumina respectively. Mechanical properties characterization which strongly depends on microstructure properties of reinforcement revealed that the presence of ( nano , micro alumina particulates lead to simultaneous increase in hardness, ultimate tensile stress (UTS, wear resistances. The results revealed that UTS, Hardness, Wear resistances increases with the increase in the percentage of reinforcement of Al2O3 when compared to the base alloy A332. The wear rates of the composites were considerably less than that of the aluminum alloy at all applied loads with increasing percentage of reinforcement when compared to the base alloy A332.

  4. Effect of graphite particle size on wear property of graphite and Al2O3 reinforced AZ91D-0.8%Ce composites

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The graphite particles and Al2O3 short fibers reinforced AZ91D-0.8%Ce composites were fabricated by squeeze-infiltration technique.The researches about the effects of different graphite particle sizes on the microstructure and wear property of the composites were performed under the condition of constant contents of graphite particles and Al2O3 short fibers.The results reveal that the grain size of the composites changes less when the graphite particle size descends.Moreover,Ce enriches around the graphite particle and Al2O3 short fibers and forms Al3Ce phase with A1 element.The graphite that works as lubricant decreases the wear loss.The wear resistance of the composites increases as the graphite particle size increases.At low load the composites have similar wear loss;at high load the composite with the largest graphite particle size has the best wear resistance.The wear mechanism of all the composites at low load is abrasive wear and oxidation wear;at high load,except the composites with the particle size of 240 μm whose wear mechanism is still abrasive wear and oxicIation wear,the wear mechanism of othcrs changes to delamination wear.

  5. Mullite fiber reinforced reaction bonded Si3N4 composites

    Science.gov (United States)

    Saleh, T.; Sayir, A.; Lightfoot, A.; Haggerty, J.

    1996-01-01

    Fracture toughnesses of brittle ceramic materials have been improved by introducing reinforcements and carefully tailored interface layers. Silicon carbide and Si3N4 have been emphasized as matrices of structural composites intended for high temperature service because they combine excellent mechanical, chemical, thermal and physical properties. Both matrices have been successfully toughened with SiC fibers, whiskers and particles for ceramic matrix composite (CMC) parts made by sintering, hot pressing or reaction forming processes. These SiC reinforced CMCs have exhibited significantly improved toughnesses at low and intermediate temperature levels, as well as retention of properties at high temperatures for selected exposures; however, they are vulnerable to attack from elevated temperature dry and wet oxidizing atmospheres after the matrix has cracked. Property degradation results from oxidation of interface layers and/or reinforcements. The problem is particularly acute for small diameter (-20 tim) polymer derived SiC fibers used for weavable toes. This research explored opportunities for reinforcing Si3N4 matrices with fibers having improved environmental stability; the findings should also be applicable to SiC matrix CMCs.

  6. Nanostructured composite reinforced material

    Science.gov (United States)

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  7. A transmission electron microscope characterization of sodium sulfate hot corrosion of silicon carbide fiber-reinforced lithium aluminosilicate glass-ceramic matrix composite

    OpenAIRE

    Hunt, Richard K.

    1994-01-01

    Sodium Sulfate hot corrosion of a SiC/LAS composite was studied using conventional transmission electron microscopy and selected area diffraction. Changes in the morphology, composition and crystallography of the phases in the glass-ceramic matrix and the fiber/matrix interface were studied. Microchemical analysis using energy dispersive x-ray spectroscopy (EDS) was also performed on all phases detected. Three samples were studied: (1) as-received, (2) no salt coating and annealed in argon, a...

  8. Investigations on the effect of added nuclei on the manufacture of conversion-reinforced ceramics by a sol-gel process

    International Nuclear Information System (INIS)

    It is well-known that the ZrO2 phase conversion from the tetragonal to the monocline phase can be used to improve the toughness at fracture of Al2O3 ceramics. The most important problems here are the control of the metastable tetragonal state of the ZrO2 and an homogeneous distribution of the ZrO2 at the wedges of the Al2O3 matrix. The ZrO2 grain size must be less than a critical size (0.5-1.0 μm) for control of the tetragonal ZrO2. As the Al2O3-ZrO2 ceramic requires a high temperature for compression, a coarsening of a growth of the ZrO2 grains beyond the critical size results from this. In order to meet these requirements, one has recently used the sol-gel process for manufacturing Al2O3-ZrO2 ceramic. (orig.)

  9. Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

    Science.gov (United States)

    Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.

    2016-04-01

    Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

  10. Fabrication and mechanical properties of AlCoNiCrFe high-entropy alloy particle reinforced Cu matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian, E-mail: chenjian@xatu.edu.cn [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Niu, Pengyun; Wei, Ting [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Hao, Liang [College of Architecture and Civil Engineering, Xi' an University of Science and Technology, Xi' an 710054 (China); Liu, Yunzi [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Wang, Xianhui, E-mail: xhwang693@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Peng, Yuli [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China)

    2015-11-15

    The AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying and the AlCoNiCrFe high-entropy alloy reinforced Cu matrix composites were subsequently fabricated by powder metallurgy. The phase constituents and morphology of the alloying powders were characterized by X-ray diffractometer and scanning electron microscope, the microstructures of the Cu base composites were characterized by scanning electron microscope and transmission electron microscope, and the compression tests were made as well. The results show that the AlCoNiCrFe high-entropy alloy can form after milling for 24 h. During sintering process, no grain growth occurs and no intermetallic phases present in the AlCoNiCrFe high-entropy alloy in the Cu base composite. Compression tests show that the AlCoNiCrFe high-entropy alloy has a better strengthening effect than metallic glasses and the yield strength of the Cu matrix composite reinforced with the AlCoNiCrFe high-entropy alloy is close to the value predicted by the Voigt model based on the equal strain assumption. - Graphical abstract: AlCoNiCrFe HEA has a better strengthening effect than metallic glasses for particulate reinforced metal matrix composites. The yield strength of the Cu base composite reinforced with the AlCoNiCrFe HEA is close to the upper bound calculated by Voigt model. - Highlights: • AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying. • A novel Cu base composite reinforced with AlCoNiCrFe was fabricated. • No grain growth and no intermetallic phase present in AlCoNiCrFe during sintering. • AlCoNiCrFe has a better strengthening effect than metallic glassy in composites.

  11. Fabrication and mechanical properties of AlCoNiCrFe high-entropy alloy particle reinforced Cu matrix composites

    International Nuclear Information System (INIS)

    The AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying and the AlCoNiCrFe high-entropy alloy reinforced Cu matrix composites were subsequently fabricated by powder metallurgy. The phase constituents and morphology of the alloying powders were characterized by X-ray diffractometer and scanning electron microscope, the microstructures of the Cu base composites were characterized by scanning electron microscope and transmission electron microscope, and the compression tests were made as well. The results show that the AlCoNiCrFe high-entropy alloy can form after milling for 24 h. During sintering process, no grain growth occurs and no intermetallic phases present in the AlCoNiCrFe high-entropy alloy in the Cu base composite. Compression tests show that the AlCoNiCrFe high-entropy alloy has a better strengthening effect than metallic glasses and the yield strength of the Cu matrix composite reinforced with the AlCoNiCrFe high-entropy alloy is close to the value predicted by the Voigt model based on the equal strain assumption. - Graphical abstract: AlCoNiCrFe HEA has a better strengthening effect than metallic glasses for particulate reinforced metal matrix composites. The yield strength of the Cu base composite reinforced with the AlCoNiCrFe HEA is close to the upper bound calculated by Voigt model. - Highlights: • AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying. • A novel Cu base composite reinforced with AlCoNiCrFe was fabricated. • No grain growth and no intermetallic phase present in AlCoNiCrFe during sintering. • AlCoNiCrFe has a better strengthening effect than metallic glassy in composites

  12. Fabrication of ceramic preforms based on Al2O3 CL 2500 powder

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2006-08-01

    Full Text Available Purpose: The aim of a work is to elaborate the method of manufacturing the porous, ceramic preforms based onAl2O3 particles used as the reinforcement in order to produce modern metal matrix composite materials.Design/methodology/approach: Semi-finished products were manufactured by the method of sintering ofceramic powder. The preform material consists of powder Condea Al2O3 Cl 2500, however, as the forming factorof the structure of canals and pores inside the ceramic, agglomerated framework the carbon fibres Sigrafil C10M250 UNS were used. The investigations of the structure of powder Al2O3 Condea Cl 2500, the used carbonfibres and the obtained ceramic preforms on the scanning electron microscope (SEM have been made. Themeasurement of permeability of the obtained materials on the specially designed station has also been made.Findings: The obtained preforms are characterised by volumetric participation of ceramic phase of 15 – 31%,what is the result of differential addition of the pores forming factor, and the high permeability indicates on “theopen porosity”.Research limitations/implications: The basic limit of the mentioned method is the possibility of obtainingpreforms of porosity less than 85%, where in case of using the ceramic fibres the pores can be more than 90%of material volumetric.Practical implications: The manufactured ceramic preforms are widely used as the reinforcement to producethe composite materials by the method of infiltration. That method allows manufacturing the metal elementslocally reinforced and the near-net shape composite products.Originality/value: The received results show the possibility of obtaining the new preforms being the cheaperalternative for semi-finished products based on the ceramic fibres and the use of carbon fibres as the poresforming agent indicate that it is the high-quality process.

  13. Microstructure and Wear Resistance of in situ NbC Particles Reinforced Ni-based Alloy Composite Coating by Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    DONG Gang; YAN Biao; DENG Qilin; YU Ting

    2012-01-01

    The in situ synthesized NbC particles reinforced Ni-based alloy composite coating was produced by laser cladding a precursor mixture of Ni-based alloy powder,graphite and niobium powders on a steel substrate.The microstructure,phase composition and wear property of the composite coating were investigated by means of scanning electron microscopy (SEM),X-ray diffraction (XRD) and dry sliding wear test.The experiment results show that the composite coating is homogeneous and free from cracks,and about 0.8 mm thick.The microstructure of the composite coating is mainly composed of NbC particles,CrB type chromium borides,γ-Ni primary dendrites,and interdendritic eutectics.CrB phases often nucleate and grow on the surface of NbC particles or in their close vicinity.NbC particles are formed via in situ reaction between niobium and graphite in the molten pool during the laser cladding process and they are commonly precipitated in three kinds of morphologies,such as quadrangle,cluster,and flower-like shape.Compared with the pure Nibased alloy coating,the microhardness of the composite coating is increased about 38%,giving a high average hardness of HV0.21000,and the wear rate of the composite coating is decreased by about 32%,respectively.These are attributed to the presence of in situ synthesized NbC particles and their well distribution in the coating.

  14. High-temperature mechanical properties and fracture mechanisms of Al–Si piston alloy reinforced with in situ TiB2 particles

    International Nuclear Information System (INIS)

    In order to assess the high-temperature performance of aluminum–silicon alloy reinforced with titanium diboride particles as potential piston material, the tensile behaviors and fracture mechanisms of in situ 4 wt% TiB2/Al–Si composite were investigated in the temperature range 25–350 °C. The tensile results revealed that the composite exhibited higher modulus than the matrix alloy at all testing temperatures, but both the matrix alloy and the composite presented similar strength levels above 200 °C. The ductility of the composite was found to be lower than that of the unreinforced matrix alloy at 25 and 200 °C, but no obvious distinction was observed at 350 °C. The effects of temperature and the presence of TiB2 particles on tensile properties of the composite had been evaluated. Fractographic morphology studies were done using scanning electron microscope, which indicated that the fracture of the composite altered from brittle to ductile mode with temperature increasing. At 25 and 200 °C, fracture was dominated by cracked silicon particles and separated TiB2 particles, while decohesion at particle–matrix interface was prevalent at 350 °C. Analysis of the fracture surfaces also showed that regions of clustered TiB2 particles were found to be the locations prone to damage in the composite at both room and high temperatures

  15. High-temperature mechanical properties and fracture mechanisms of Al–Si piston alloy reinforced with in situ TiB{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Han, Gang [School of Mechanical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081 (China); Zhang, Weizheng, E-mail: zhangwz@bit.edu.cn [School of Mechanical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081 (China); Zhang, Guohua; Feng, Zengjian; Wang, Yanjun [Shandong Binzhou Bohai Piston Co., Ltd., Binzhou 256602 (China)

    2015-05-01

    In order to assess the high-temperature performance of aluminum–silicon alloy reinforced with titanium diboride particles as potential piston material, the tensile behaviors and fracture mechanisms of in situ 4 wt% TiB{sub 2}/Al–Si composite were investigated in the temperature range 25–350 °C. The tensile results revealed that the composite exhibited higher modulus than the matrix alloy at all testing temperatures, but both the matrix alloy and the composite presented similar strength levels above 200 °C. The ductility of the composite was found to be lower than that of the unreinforced matrix alloy at 25 and 200 °C, but no obvious distinction was observed at 350 °C. The effects of temperature and the presence of TiB{sub 2} particles on tensile properties of the composite had been evaluated. Fractographic morphology studies were done using scanning electron microscope, which indicated that the fracture of the composite altered from brittle to ductile mode with temperature increasing. At 25 and 200 °C, fracture was dominated by cracked silicon particles and separated TiB{sub 2} particles, while decohesion at particle–matrix interface was prevalent at 350 °C. Analysis of the fracture surfaces also showed that regions of clustered TiB{sub 2} particles were found to be the locations prone to damage in the composite at both room and high temperatures.

  16. Particles geometry influence in the thermal stress level in an SiC reinforced aluminum matrix composite considering the material non-linear behavior

    International Nuclear Information System (INIS)

    An analytical methodology was developed to predict the thermal stress level that occurs in a metallic matrix composite reinforced with SiC particles, when the temperature decreases from 600 deg C to 20 deg C during the fabrication process. This analytical development is based on the Eshelby method, dislocation mechanisms, and the Maxwell-Boltzmann distribution model. The material was assumed to have a linear elastic behavior. The analytical results from this formulation were verified against numerical linear analyses that were performed over a set of random non-uniform distribution of particles that covers a wide range of volumetric ratios. To stick with the analytical hypothesis, particles with round geometry were used. Each stress distribution, represented by the isostress curves at ΔT=-580 deg C, was analyzed with an image analyzer. A statistical procedure was applied to obtain the most probable thermal stress level. Analytical and numerical results compared very well. Plastic deformation as well as particle geometry can alter significantly the stress field in the material. To account for these effects, in this work, several numerical analyses were performed considering the non-linear behavior for the aluminum matrix and distinct particle geometries. Two distinct sets of data with were used. To allow a direct comparison, the first set has the same models (particle form, size and distribution) as used previously. The second set analyze quadrilateral particles and present very tight range of volumetric ratio, closer to what is found in actual SiC composites. A simple and fast algorithm was developed to analyze the new results. The comparison of these results with the previous ones shows, as expected, the strong influence of the elastic-plastic behavior of the aluminum matrix on the composite thermal stress distribution due to its manufacturing process and shows, also, a small influence of the particles geometry and volumetric ratio. (author)

  17. Celsian Glass-Ceramic Matrix Composites

    Science.gov (United States)

    Bansal, Narottam P.; Dicarlo, James A.

    1996-01-01

    Glass-ceramic matrix reinforced fiber composite materials developed for use in low dielectric applications, such as radomes. Materials strong and tough, exhibit low dielectric properties, and endure high temperatures.

  18. Actively Cooled Ceramic Composite Nozzle Material Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase I Project demonstrated the capability of the Pyrowave? manufacturing process to produce fiber-reinforced ceramics (FRCs) with integral metal features,...

  19. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part I: Experimental Analysis

    Science.gov (United States)

    Longbiao, Li

    2016-04-01

    This paper presents an experimental analysis on the fatigue behavior in C/SiC ceramic-matrix composites (CMCs) with different fiber preforms, i.e., unidirectional, cross-ply and 2.5D woven, at room and elevated temperatures in air atmosphere. The experimental fatigue life S - N curves of C/SiC composites corresponding to different stress levels and test conditions have been obtained. The damage evolution processes under fatigue loading have been analyzed using fatigue hysteresis modulus and fatigue hysteresis loss energy. By comparing the experimental fatigue hysteresis loss energy with theoretical computational values, the interface shear stress corresponding to different peak stress, fiber preforms and test conditions have been estimated. It was found that the degradation of interface shear stress and fibres strength caused by oxidation markedly decreases the fatigue life of C/SiC composites at elevated temperature.

  20. Tensile creep characteristics of Sn–3.5Ag–0.5Cu (SAC355) solder reinforced with nano-metric ZnO particles

    International Nuclear Information System (INIS)

    Recently, nano-composite solders have been developed in the electronic packaging materials industry to improve the mechanical response of solder joints to be used in service under different conditions. In this study mechanical mixing has been used to disperse nano-metric ZnO particles in Sn–3.5Ag–0.5Cu (SAC355) solder at 420 °C for 2 h. In comparison with SAC355 solder, addition of nano-metric ZnO particles effectively suppressed the formation and restricted the volume fraction of the Ag3Sn and Cu6Sn5 intermetallic compound particles, lowering grain sizes and controlled the growth of β-Sn grains in the matrix. An improvement in tensile creep resistance of the reinforced SAC355 composite is noticed. This improvement seems to be due to its effect in structural refinement and makes the composite solder to display a large creep life time. The addition of nano-metric ZnO particles keeps the melting temperature nearly at the SAC355 level, indicating that the composite solder is fit for the existing soldering process

  1. How Sensitive Is the Elasticity of Hydroxyapatite-Nanoparticle-Reinforced Chitosan Composite to Changes in Particle Concentration and Crystallization Temperature?

    Science.gov (United States)

    Wang, Kean; Liao, Kin; Goh, Kheng Lim

    2015-01-01

    Hydroxyapatite (HA) nanoparticle-reinforced chitosan composites are biocompatible and biodegradable structural materials that are used as biomaterials in tissue engineering. However, in order for these materials to function effectively as intended, e.g., to provide adequate structural support for repairing damaged tissues, it is necessary to analyse and optimise the material processing parameters that affect the relevant mechanical properties. Here we are concerned with the strength, stiffness and toughness of wet-spun HA-reinforced chitosan fibres. Unlike previous studies which have addressed each of these parameters as singly applied treatments, we have carried out an experiment designed using a two-factor analysis of variance to study the main effects of two key material processing parameters, namely HA concentration and crystallization temperature, and their interactions on the respective mechanical properties of the composite fibres. The analysis reveals that significant interaction occurs between the crystallization temperature and HA concentration. Starting at a low HA concentration level, the magnitude of the respective mechanical properties decreases significantly with increasing HA concentration until a critical HA concentration is reached, at around 0.20–0.30 (HA mass fraction), beyond which the magnitude of the mechanical properties increases significantly with HA concentration. The sensitivity of the mechanical properties to crystallization temperature is masked by the interaction between the two parameters—further analysis reveals that the dependence on crystallization temperature is significant in at least some levels of HA concentration. The magnitude of the mechanical properties of the chitosan composite fibre corresponding to 40 °C is higher than that at 100 °C at low HA concentration; the reverse applies at high HA concentration. In conclusion, the elasticity of the HA nanoparticle-reinforced chitosan composite fibre is sensitive to HA

  2. Strengthening of steels by ceramic phases

    OpenAIRE

    Feng, Yujie

    2013-01-01

    Production of ceramic reinforced thin sheet steel composites for automotive application with low density, high elastic modulus and strength is the aim of current study. Within this work, potential of various ceramic phases and possible processing routes were studied, summarized and compared through literature research. Laboratory production of TiC, TiB2 and Fe2B reinforced steel composites through conventional melting-casting route, twin roller route and powder metallurgy method were carried ...

  3. Effect of heat treatment on microstructure and mechanical properties of ZrC particles reinforced tungsten-matrix composites

    International Nuclear Information System (INIS)

    A 20 vol.% ZrCp/W composite is fabricated by hot-pressing, and its mechanical properties can be significantly improved by the addition of ZrC particles. On the other side, the residual pores within ZrC particles clustering regions which are some latent microcrack sources are mainly caused by the relative low sinterability of ZrC particles. In order to eliminate the pores within the particle clusters, the as-sintered composite is annealed at 2300 deg. C for 1 h. The microstructure of the annealed composite becomes more uniform and densified. Components of the as-sintered and annealed composites are composed of a dilute solid solution tungsten-matrix, (Zr, W)C solid solution particles and a new W2C phase, but the content of W2C phase in the annealed composite increases. After annealing, the strength properties of the composite decrease, but its plasticity increases.

  4. Influence of the Sr and Mg Alloying Additions on the Bonding Between Matrix and Reinforcing Particles in the AlSi7Mg/SiC-Cg Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Dolata A. J.

    2016-06-01

    Full Text Available The aim of the work was to perform adequate selection of the phase composition of the composite designated for permanent - mould casting air compressor pistons. The hybrid composites based on AlSi7Mg matrix alloy reinforced with mixture of silicon carbide (SiC and glassy carbon (Cg particles were fabricated by the stir casting method. It has been shown that the proper selection of chemical composition of matrix alloy and its modification by used magnesium and strontium additions gives possibility to obtain both the advantageous casting properties of composite suspensions as well as good bonding between particles reinforcements and matrix.

  5. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    Science.gov (United States)

    Ebrahimpour, Omid

    In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the

  6. Improved performance of diatomite-based dental nanocomposite ceramics using layer-by-layer assembly

    Directory of Open Access Journals (Sweden)

    Lu X

    2012-04-01

    Full Text Available Xiaoli Lu1,2, Yang Xia1, Mei Liu1, Yunzhu Qian3, Xuefeng Zhou4, Ning Gu4, Feimin Zhang1,41Institute of Stomatology, Nanjing Medical University, Nanjing, 2Nantong Stomatological Hospital, Nantong, 3Center of Stomatology, The Second Affiliated Hospital of Suzhou University, Suzhou, 4Suzhou Institute, Southeast University, Suzhou, People's Republic of ChinaAbstract: To fabricate high-strength diatomite-based ceramics for dental applications, the layer-by-layer technique was used to coat diatomite particles with cationic [poly(allylamine hydrochloride] and anionic [poly(sodium 4-styrenesulfonate] polymers to improve the dispersion and adsorption of positively charged nano-ZrO2 (zirconia as a reinforcing agent. The modified diatomite particles had reduced particle size, narrower size distribution, and were well dispersed, with good adsorption of nano-ZrO2. To determine the optimum addition levels for nano-ZrO2, ceramics containing 0, 20, 25, 30, and 35 wt% nano-ZrO2 were sintered and characterized by the three-point bending test and microhardness test. In addition to scanning electron microscopy, propagation phase-contrast synchrotron X-ray microtomography was used to examine the internal structure of the ceramics. The addition of 30 wt% nano-ZrO2 resulted in the highest flexural strength and fracture toughness with reduced porosity. Shear bond strength between the core and veneer of our diatomite ceramics and the most widely used dental ceramics were compared; the shear bond strength value for the diatomite-based ceramics was found to be significantly higher than for other groups (P < 0.05. Our results show that diatomite-based nanocomposite ceramics are good potential candidates for ceramic-based dental materials.Keywords: layer-by-layer, diatomite, nanoceramics, zirconia (ZrO2, dental materials

  7. Retarding the electromigration effects to the eutectic SnBi solder joints by micro-sized Ni-particles reinforcement approach

    International Nuclear Information System (INIS)

    Research highlights: → We used a revised solder joints with one-dimension geometry that can help us to investigate the true failure mechanisms of solder joints induced by EM. → One of possible solutions to inhibit the EM effect to solder joint can be achieved by adding micro- or nano-sized metal particles into it. → Micro-sized Ni particles were selected as the reinforcement to retard the phase segregation in the eutectic SnBi solder joints under high current density (104 A/cm2). It has been approved in this study that Ni particles can act as obstacles to obstruct the fast diffusion channel along the phase boundaries in the eutectic SnBi system. - Abstract: Electromigration (EM) has become one of the reliability concerns to the electronic solder joint due to its increasing capacity to bear the high current density (104 A/cm2). Although the failure induced by EM can trigger a large void across the entire cathode interface, no effective solutions are presented throughout years of effort on this problem. Here, the composite solder joints are addressed to demonstrate their potential roles on solving the EM issue in the eutectic SnBi solder joints. Micro-sized Ni particles were selected to intentionally add into the solder matrix due to their extensive application as a barrier layer in the under-bump-metallization (UBM) of flip chip solder joints. The ultimate results illustrated that the Ni particles can react with Sn to form the cluster-type Sn-Ni intermetallic compounds (IMCs) inside the solder matrix after the first reflow. Accordingly, the phase segregation of Sn and Bi was significantly inhibited during the current stressing, demonstrating the Sn-Ni IMCs can act as the obstacles to obstruct the movement of dominant diffusion entity (Bi atoms/ions) along the phase boundaries.

  8. Properties of Al2O3 nano-particle reinforced copper matrix composite coatings prepared by pulse and direct current electroplating

    International Nuclear Information System (INIS)

    Highlights: → The influence of Al2O3 is studied on morphologies of the DC and PC applied coatings. → The influence of Al2O3 is studied on the DC and PC coating thicknesses. → The influence of Al2O3 is studied on wear resistance. → The effect of Al2O3 is studied on the porosity and corrosion resistance. -- Abstract: Cu-Al2O3 nano-composite coatings have high potential for use in applications in which high mechanical properties together with high corrosion resistance are required. In the present study it is intended to produce copper nano-alumina composite coatings with various nano-alumina contents in order to investigate the effect of alumina reinforcement particles on corrosion resistance and mechanical properties such as hardness and wear resistance. The composite coatings were deposited using direct current (DC) and pulse current (PC) plating. The microstructures of the coatings produced from both methods were examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear behaviors, micro hardness, coating thickness, corrosion rate and coating porosity were examined using appropriate methods. Compared to DC deposition, PC plating facilitated higher amounts of particle incorporation with more uniform distribution. The results indicated that the mechanical properties of the applied coatings with incorporated nano-alumina reinforcement were far more superior as compared to its own matrix as well as non-composite copper coatings. It was also found out that increasing the amount of nano-alumina content in the coating, led to enhanced general properties of the coatings.

  9. Residual stress and damage development in the aluminium alloy EN AW-6061 particle reinforced with Al2O3 under thermal fatigue loading

    International Nuclear Information System (INIS)

    Thermal fatigue (TF) tests were performed on the aluminium alloy EN AW-6061-T6, non-reinforced and reinforced with 15 and 22 vol.% Al2O3 particles, respectively. The MMCs were produced by stir casting followed by hot extrusion. Thermal fatigue tests were performed using a 6 kW diode laser with a beam area of about 8 mm x 8 mm focused on the centre of one flat side of disc shaped specimens. The reverse side was either attached to a water-cooled aluminium plate or directly cooled by water. The maximum temperature Tmax of the irradiated side was varied between 573 and 773 K. The heating rate was 50 K/s. Residual stresses in the matrix alloy were measured by X-ray diffraction using the sin2ψ-method after T6 heat treatment and after defined temperature cycles. Initial residual compressive stresses between -20 and -65 MPa result from the machining processes before T6 heat treatment. During the first temperature cycle the residual stresses in all materials change to tension at almost all Tmax. The peak value of the residual stresses reaches 50 up to 65 MPa and is nearly independent from Tmax. Damage evolution was observed by light optical microscope and SEM after the same cycles as the residual stress measurements. Grain boundary reliefs arise and increase in all materials with increasing number of TF cycles and intergranular damage of EN AW-6061 and the matrix alloy of the MMCs is observed. Close to the particles, damage is more pronounced due to thermal and mechanical mismatch of the phases. Four mechanisms causing damage and residual stress development could be identified: thermally induced global deformation due to inhomogeneous distribution of temperature, thermally induced local deformation due to coefficient of thermal expansion (CTE) mismatch (different αth of both phases), mechanically induced local deformation due to different deformation behaviour of both phases and overaging. In the non-reinforced alloy global deformation is the dominant mechanism while in

  10. Aluminium composite casting dispersion reinforced with iron-aluminium and silicon carbide phases

    Directory of Open Access Journals (Sweden)

    B. Formanek

    2010-10-01

    Full Text Available Aluminium matrix composite with dispersion-reinforced, made by similar to stircasting process was characterised. The mixture of powders was produced by the process of mechanical agglomeration of powdered FexAly and SiC with aluminium. The chemical composition ofagglomerates was selected in a way such as to obtain 25 wt.% reinforcement of the AlSi9Cu4 silumin matrix. Applying thermal analysis ATD, the alloy solidification process was determined, reading out the typical solidification parameters. The methods of light and scanning microscopy were used to reveal the structure of composite casting. Changes in chemical composition and phase composition of particles of the FeAl intermetallic phase in aluminium matrix were confirmed. The structure of silumin casting with matrix containing microregions of ceramic and intermetallic phases, typical of hybrid reinforcements, was obtained.

  11. Steady- and transient-state analysis of fully ceramic microencapsulated fuel with randomly dispersed tristructural isotropic particles via two-temperature homogenized model-I: Theory and method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yoon Hee; Cho, Bum Hee; Cho, Nam Zin [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-06-15

    As a type of accident-tolerant fuel, fully ceramic microencapsulated (FCM) fuel was proposed after the Fukushima accident in Japan. The FCM fuel consists of tristructural isotropic particles randomly dispersed in a silicon carbide (SiC) matrix. For a fuel element with such high heterogeneity, we have proposed a two-temperature homogenized model using the particle transport Monte Carlo method for the heat conduction problem. This model distinguishes between fuel-kernel and SiC matrix temperatures. Moreover, the obtained temperature profiles are more realistic than those of other models. In Part I of the paper, homogenized parameters for the FCM fuel in which tristructural isotropic particles are randomly dispersed in the fine lattice stochastic structure are obtained by (1) matching steady-state analytic solutions of the model with the results of particle transport Monte Carlo method for heat conduction problems, and (2) preserving total enthalpies in fuel kernels and SiC matrix. The homogenized parameters have two desirable properties: (1) they are insensitive to boundary conditions such as coolant bulk temperatures and thickness of cladding, and (2) they are independent of operating power density. By performing the Monte Carlo calculations with the temperature-dependent thermal properties of the constituent materials of the FCM fuel, temperature-dependent homogenized parameters are obtained.

  12. Effect of nepheline syenite particle size on diametrical compression strength and reliability of extruded ceramic Raschig rings used in packed towers

    International Nuclear Information System (INIS)

    In order to understand the effect of nepheline syenite particle size on physico-chemical properties of ceramic Raschig rings, the fluxing agent was grinded at different milling times. The compositions were prepared by blending the illitic-kaolinitic clay and pre-grinded particles. The rings were shaped by a laboratory extruder and then were sintered at 1200 degree centigrade. The mechanical reliability of sintered specimens was mathematically described by Weibull theory and the effect of pre-grinding of fluxing agent on Weibull modulus was evaluated by measuring the diametrical compression strength. Weibull modulus and strength were the criteria for selecting the suitable particle size range of nepheline syenite. It was found that the pre-grinding of nepheline syenite acts as fairly strong parameter on microstructure of rings. The investigation concludes that reliable rings can be fabricated if the particle size of nepheline syenite is arranged between 53 and 75 μm. This enhancement in reliability is valuable in packed towers. (Author)

  13. The effect of particle addition and fibrous reinforcement on epoxy-matrix composites for severe sliding conditions

    DEFF Research Database (Denmark)

    Larsen, Thomas Ricco Ølholm; Løgstrup Andersen, Tom; Thorning, Bent;

    2008-01-01

    This paper reports production and tribological testing of epoxy-matrix composites for dry-sliding conditions. The examined composites are produced using the following components: epoxy resin (EP), glass fiber weave (G), carbon/aramid hybrid weave (CA), PTFE particles and nano-scale CuO particles...... properties are seen when the fibers are parallel and anti-parallel (P-AP) to the sliding direction compared to normal and parallel (N-P). Experiments with incorporating micro-scale PTFE particles and nano-scale CuO particles, respectively, into the epoxy resin along with the carbon/aramid weave shows no...... difference in friction but minor improvements in wear. When micro-scale PTFE particles are incorporated into the neat epoxy resin, i.e. without fibers, an increase in and a decrease in A are measured. When the same is done with nano-CuO a deterioration of both friction and wear properties are seen. At the...

  14. Method of making multilayered titanium ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, George T., II; Hansen; Jeffrey S.; Oden; Laurance L.; Turner; Paul C.; Ochs; Thomas L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  15. Microstructure of a Ni Matrix Composite Coating Reinforced by In-situ TiC Particles Using Plasma Cladding

    Institute of Scientific and Technical Information of China (English)

    WUYu-ping; WANGZe-hua; LINPing-hua

    2004-01-01

    Plasma cladding process was used to prepare the TiC/Ni composite coating on the mild steel substrates. The TiC particles were synthesized in-situ. Microstructure and properties of the coating were investigated by optical microscopy, X-Ray diffraction, SEM, TEM and microhardness tester. The results show that the interface between the coating and the substrate is metallurgically bonded. The coating was uniform and almost defect-free when [Ti+C] varied from 10% to 20% after ball milling. The microstructure of the coating is mainly composed of γ-Ni dendrite, interdendritic eutectic (γ-Ni austenite, M23C6 and CrB) and TiC particles. Most of the TiC particles are spherical and a small fraction is blocky in size of 1-2μm. The TiC particles are smaller at the bottom than near the top of the coating. The coating has a gradient microstructure and a highest hardness of 1000Hv0.1.

  16. Synthesis and characterization of monoclinic KGd(WO4)2 particles for non-cubic transparent ceramics

    Science.gov (United States)

    Thangaraju, D.; Durairajan, A.; Balaji, D.; Moorthy Babu, S.

    2013-02-01

    Monoclinic KGd(WO4)2 (KGW) particles were synthesized using polymeric metal complex sol-gel synthesis method. The derived particles were made as colloidal suspension form for better rotation of particles to have optimum response for applied magnetic field. The KGW fine particle suspension was prepared using electrostatic repulsion by electrolyte polymer. Prepared suspension was kept at 2 T and particles were settled using electrophoretic sedimentation using pH adjustment. The derived sediment was dried at 100 °C and the properties were characterized using XRD.

  17. Novel processing of bioglass ceramics from silicone resins containing micro- and nano-sized oxide particle fillers.

    Science.gov (United States)

    Fiocco, L; Bernardo, E; Colombo, P; Cacciotti, I; Bianco, A; Bellucci, D; Sola, A; Cannillo, V

    2014-08-01

    Highly porous scaffolds with composition similar to those of 45S5 and 58S bioglasses were successfully produced by an innovative processing method based on preceramic polymers containing micro- and nano-sized fillers. Silica from the decomposition of the silicone resins reacted with the oxides deriving from the fillers, yielding glass ceramic components after heating at 1000°C. Despite the limited mechanical strength, the obtained samples possessed suitable porous architecture and promising biocompatibility and bioactivity characteristics, as testified by preliminary in vitro tests. PMID:23946157

  18. Ni-AlxNiy core–shell structured particle reinforced Al-based composites fabricated by in-situ powder metallurgy technique

    International Nuclear Information System (INIS)

    Ni-AlxNiy core–shell structured particle reinforced aluminum based composites were fabricated using in-situ powder metallurgy method. Scanning electron microscope, X-ray diffraction, density analysis, hardness and compressive tests were used to investigate the effects of volume fraction of Ni particles and sintering atmosphere on the microstructures and mechanical properties of the composites. It has been shown that compared to Ar sintering atmosphere, N2 atmosphere is active sintering atmosphere for fabricating the composites. The AlN formed during the sintering process, which can substantially increase the density and hardness of the composites. The strength of the composites sintered under N2 atmosphere is higher than that of the composites sintered under Ar, while the ductility is slightly lower. It can be confirmed that the Ni-AlxNiy core–shell structures are of great benefit not only to increase the strength but also to remain the plasticity of the composites. - Highlights: • A new metal matrix composite (MMC) has been developed. • The developed MMC has a matrix/shell/core structure. • The developed MMC has both high strength and plasticity

  19. In situ Al{sub 2}O{sub 3} particle-reinforced Al and Cu matrix composites synthesized by displacement reactions

    Energy Technology Data Exchange (ETDEWEB)

    Yang Bin, E-mail: byang@ustb.edu.c [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Sun Miao; Gan Guisheng; Xu Cunguan; Huang Zanjun [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Zhang Haibo; Fang Zhigang Zak [Department of Metallurgical Engineering, University of Utah, 135 South 1460 East Room 412, Salt Lake City, UT 84112-0114 (United States)

    2010-04-02

    An innovative in situ reaction technique is developed for the synthesis of Al{sub 2}O{sub 3}/Al and Al{sub 2}O{sub 3}/Cu composites. This technique provides a new approach overcoming the problems of loss and agglomeration of reinforcement particles when the particles are added directly into their matrixes by a conventional ex situ technique. The experimental results have shown that the presence of network Al(Cu)-CuAl{sub 2} eutectic, which is detrimental not only to the fracture toughness, but also to the stability of the microstructure, can be reduced from the final product by introducing two or more oxides into the synthesis. Moreover, the network CuAl{sub 2} phase can be eliminated entirely only by changing Al matrix into Cu matrix when Al amount is not excess in the Al-CuO preforms. The mechanisms of formation or absence of Al(Cu)-CuAl{sub 2} eutectic in the Al{sub 2}O{sub 3}/Al and Al{sub 2}O{sub 3}/Cu composites are explained based upon thermodynamics of the systems. The modification of the microstructures in the in situ synthesis Al{sub 2}O{sub 3}/Al, Al{sub 2}O{sub 3}/Al-Si-Cu, Al{sub 2}O{sub 3}/Al-Si-Cu-Mn and Al{sub 2}O{sub 3}/Cu composites can be understood in the light of thermodynamics.

  20. Ceramic matrix and resin matrix composites - A comparison

    Science.gov (United States)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  1. Ceramic matrix and resin matrix composites: A comparison

    Science.gov (United States)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  2. In vitro comparative bond strength of contemporary self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion.

    Science.gov (United States)

    Blatz, Markus B; Phark, Jin-Ho; Ozer, Fusun; Mante, Francis K; Saleh, Najeed; Bergler, Michael; Sadan, Avishai

    2010-04-01

    This study compared shear bond strengths of six self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. One hundred twenty zirconia samples were air-abraded (group SB; n = 60) or left untreated (group NO). Composite cylinders were bonded to the zirconia samples with either BisCem (BC), Maxcem (MC), G-Cem (GC), RelyX Unicem Clicker (RUC), RelyX Unicem Applicator (RUA), or Clearfil SA Cement (CSA). Shear bond strength was tested after thermocycling, and data were analyzed with analysis of variance and Holm-Sidak pairwise comparisons. Without abrasion, RUA (8.0 MPa), GC (7.9 MPa), and CSA (7.6 MPa) revealed significantly higher bond strengths than the other cements. Air-particle abrasion increased bond strengths for all test cements (p CSA (18.4 MPa) revealed the highest bond strengths in group SB. Bond strengths of self-adhesive resin cements to zirconia were increased by air-particle abrasion. Cements containing adhesive monomers (MDP/4-META) were superior to other compositions. PMID:19415350

  3. Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

    NARCIS (Netherlands)

    Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

    2008-01-01

    Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

  4. Thermal and mechanical behavior of metal matrix and ceramic matrix composites

    Science.gov (United States)

    Kennedy, John M. (Editor); Moeller, Helen H. (Editor); Johnson, W. S. (Editor)

    1990-01-01

    The present conference discusses local stresses in metal-matrix composites (MMCs) subjected to thermal and mechanical loads, the computational simulation of high-temperature MMCs' cyclic behavior, an analysis of a ceramic-matrix composite (CMC) flexure specimen, and a plasticity analysis of fibrous composite laminates under thermomechanical loads. Also discussed are a comparison of methods for determining the fiber-matrix interface frictional stresses of CMCs, the monotonic and cyclic behavior of an SiC/calcium aluminosilicate CMC, the mechanical and thermal properties of an SiC particle-reinforced Al alloy MMC, the temperature-dependent tensile and shear response of a graphite-reinforced 6061 Al-alloy MMC, the fiber/matrix interface bonding strength of MMCs, and fatigue crack growth in an Al2O3 short fiber-reinforced Al-2Mg matrix MMC.

  5. Supported microporous ceramic membranes

    Science.gov (United States)

    Webster, E.; Anderson, M.

    1993-12-14

    A method for the formation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms. 4 figures.

  6. Study of new CaO-SiO/sub 2/-P/sub 2/O/sub 5/CaF/sub 2/ bioactive ceramic

    International Nuclear Information System (INIS)

    A new bioactive glass ceramic having, composition 48CaO-32SiO/sub 2/-16P/sub 2/O/sub 5/-4CaF/sub 2/ has been developed and studied for its physical and biological properties. Like the natural bone in which spastic particles are reinforced by collagen, in the present glass-ceramic, fine grained ceramic particles embedded in a glass matrix. X-ray diffraction analysis reveals wollastonite and oxyfluorapatite as the crystalline part of the glass-ceramic. Scanning electron microscopy of the samples has been carried out to see the grain size and grain distribution. Bending and compressive strength of the glass ceramic have been carried out to measured and found to be 208.60 m.Pa and 788.61 M.Pa respectively. Growth of apatite layer, which is responsible for bonding the broken part of a natural bone, on a bioactive glass-ceramic in a simulated body fluid has been studied. A small rectangular piece of this glass-ceramic has also been implanted successfully in a dog's tibia. (author)

  7. Anchor reinforcements

    Energy Technology Data Exchange (ETDEWEB)

    Levkovich, P.Ye.; Sal' nikov, V.K.; Savich, N.S.

    1980-11-30

    An anchor reinforcement includes an anchor shaft, an elastic jig with a separator wall having compartments placed parallely along it and filled with reinforcement material and a device for destroying the jig wall separator. To quickly put the anchor in place and increase the reliability of the reinforcement by mixing the reinforcement material components better, the device for destroying the jig separator wall was made in the shape of a shovel, fastened to the anchor shaft and the separator wall has a longitudinal hollow for holding the anchor shaft/shovel.

  8. Elaboration of silicon carbides nano particles (SiC): from the powder synthesis to the sintered ceramic; Elaboration de ceramiques nanostructurees en carbure de silicium (SiC): de la synthese de poudre a la ceramique frittee

    Energy Technology Data Exchange (ETDEWEB)

    Reau, A. [CEA Saclay, Dept. des Materiaux pour le Nucleaire (DEN/DANS/DMN/SRMA), 91 - Gif-sur-Yvette (France)

    2008-07-01

    Materials for the reactor cores of the fourth generation will need materials supporting high temperatures with fast neutrons flux. SiC{sub f}/SiC ceramics are proposed. One of the possible elaboration process is to fill SiC fiber piece with nano particles SiC powder and to strengthen by sintering. The aim of this thesis is to obtain a nano structured SiC ceramic as a reference for the SiC{sub f}/SiC composite development and to study the influence of the fabrication parameters. (A.L.B.)

  9. Ceramic fiber filter technology

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  10. Recrystallization texture and Young`s modulus of ceramic particle dispersed ferrite steel bars; Ceramics ryushi wo bisai bunsan saseta ferrite bo ko no saikessho shugo soshiki to Young ritsu

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, S.; Asabe, K.; Nishiguchi, M.; Maehara, Y. [Sumitomo Metal Industries, Ltd., Osaka (Japan)

    1996-09-01

    Relation was examined between Young`s modulus and the formation behavior of recrystallization texture, in regard to the material in which ferrite steel powders with ceramic particles dispersed were hot-extruded and heat-treated under various conditions. In making samples on an experimental basis, a mechanical alloying method was employed using an electrolytic iron powder and the reagent powder of Cr, Al and Y2O3 as raw materials. The mechanical alloying process was performed by ball mill in the Ar atmosphere at 173Ks. After encapsulation and after heating to 1,323K or 1,423K, hot extrusion was performed. The following results were obtained by the experiment. The Young`s modulus increased about 30% in the extruding direction by applying a heat treatment in a specific temperature range, and 282GPa was obtained which was close to the maximum theoretical value. This was due to the change from (110) extrusion texture to (111) texture. At the heat treatment temperature higher than this, (311) recrystallization texture became the principal azimuth, resulting in lowering of the Young`s modulus. 12 refs., 8 figs., 1 tab.

  11. Mechanical properties of dental composite materials reinforced with micro and nano-size Al2O3 filler particles

    International Nuclear Information System (INIS)

    Composite specimens were prepared by dispersion of various amounts of nano-sized Al2O3 fillers in a monomer system containing 60percentBis-GMA and 40percentTEGDMA. For comparative purposes, composite samples containing micrometer size Al2O3 fillers were also prepared following the same procedure. The mechanical properties of the light- cured samples were assessed by three-point flexural strength, diametral tensile strength, and microhardness tests. The results indicated a more than hundred percent increase in the flexural strength and nearly an eighty percent increase in the diametral tensile strength values in the samples containing nano-size Al2O3 filler particles. It is interesting to note that, this improvement was observed at a much lower nano-size filler content. Fracture surfaces analyzed by scanning electron microscopy, indicated a brittle type of fracture in both sets of specimens.

  12. Structural Ceramics

    Science.gov (United States)

    1986-01-01

    This publication is a compilation of abstracts and slides of papers presented at the NASA Lewis Structural Ceramics Workshop. Collectively, these papers depict the scope of NASA Lewis' structural ceramics program. The technical areas include monolithic SiC and Si3N4 development, ceramic matrix composites, tribology, design methodology, nondestructive evaluation (NDE), fracture mechanics, and corrosion.

  13. Advanced Ceramics

    International Nuclear Information System (INIS)

    The First Florida-Brazil Seminar on Materials and the Second State Meeting about new materials in Rio de Janeiro State show the specific technical contribution in advanced ceramic sector. The others main topics discussed for the development of the country are the advanced ceramic programs the market, the national technic-scientific capacitation, the advanced ceramic patents, etc. (C.G.C.)

  14. PIXE (particle induced X-ray emission): A non-destructive analysis method adapted to the thin decorative coatings of antique ceramics

    International Nuclear Information System (INIS)

    Recent trends in study of Greek and Roman potteries have been to develop non-abrasive methods to determine the elemental composition of their thin coatings. This paper investigates the potential of PIXE (particle induced X-ray emission) in this field. This technique has been currently used to determine the bulk elemental composition of several types of artifacts because of its fast and simultaneous ability to measure a large number of elements with good accuracy and without any damage to the sample. However, until now it has never been applied to the measurement of the composition of thin layers owing to the difficulty in limiting the depth of analysis to the layer thickness. In this paper, we show, through a comparative study of reference clay pellets and thin coatings of Terra Sigillata ceramics that reducing the energy of the particle beam the problem can be solved. The decrease of proton energy from 3 MeV (standard condition) to 1.5 MeV allowed us to limit the analyzed depth to the coating thickness without significant alteration of the results. Quantitative elemental analysis remains possible and the quality of results is similar to the one obtained from electron microprobe.

  15. PIXE (particle induced X-ray emission): A non-destructive analysis method adapted to the thin decorative coatings of antique ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Y. [CNRS, CEMES, BP 94347, 29 rue J. Marvig, F-31055 Toulouse (France); Universite de Toulouse, UPS, INSA, CEMES, F-31055 Toulouse (France); Sciau, Ph., E-mail: philippe.sciau@cemes.fr [CNRS, CEMES, BP 94347, 29 rue J. Marvig, F-31055 Toulouse (France); Universite de Toulouse, UPS, INSA, CEMES, F-31055 Toulouse (France); Bouquillon, A.; Pichon, L. [C2RMF, 14 quai F. Mitterrand, F-75001 Paris Cedex 01 (France); Parseval, Ph. de [Universite de Toulouse, CNRS, IRD, GET, 14 av. E. Belin, F-31400 Toulouse (France)

    2012-11-15

    Recent trends in study of Greek and Roman potteries have been to develop non-abrasive methods to determine the elemental composition of their thin coatings. This paper investigates the potential of PIXE (particle induced X-ray emission) in this field. This technique has been currently used to determine the bulk elemental composition of several types of artifacts because of its fast and simultaneous ability to measure a large number of elements with good accuracy and without any damage to the sample. However, until now it has never been applied to the measurement of the composition of thin layers owing to the difficulty in limiting the depth of analysis to the layer thickness. In this paper, we show, through a comparative study of reference clay pellets and thin coatings of Terra Sigillata ceramics that reducing the energy of the particle beam the problem can be solved. The decrease of proton energy from 3 MeV (standard condition) to 1.5 MeV allowed us to limit the analyzed depth to the coating thickness without significant alteration of the results. Quantitative elemental analysis remains possible and the quality of results is similar to the one obtained from electron microprobe.

  16. PIXE (particle induced X-ray emission): A non-destructive analysis method adapted to the thin decorative coatings of antique ceramics

    Science.gov (United States)

    Leon, Y.; Sciau, Ph.; Bouquillon, A.; Pichon, L.; de Parseval, Ph.

    2012-11-01

    Recent trends in study of Greek and Roman potteries have been to develop non-abrasive methods to determine the elemental composition of their thin coatings. This paper investigates the potential of PIXE (particle induced X-ray emission) in this field. This technique has been currently used to determine the bulk elemental composition of several types of artifacts because of its fast and simultaneous ability to measure a large number of elements with good accuracy and without any damage to the sample. However, until now it has never been applied to the measurement of the composition of thin layers owing to the difficulty in limiting the depth of analysis to the layer thickness. In this paper, we show, through a comparative study of reference clay pellets and thin coatings of Terra Sigillata ceramics that reducing the energy of the particle beam the problem can be solved. The decrease of proton energy from 3 MeV (standard condition) to 1.5 MeV allowed us to limit the analyzed depth to the coating thickness without significant alteration of the results. Quantitative elemental analysis remains possible and the quality of results is similar to the one obtained from electron microprobe.

  17. Microstructure and Wear Resistance of Plasma-Sprayed Molybdenum Coating Reinforced by MoSi2 Particles

    Science.gov (United States)

    Yan, Jianhui; He, Zheyu; Wang, Yi; Qiu, Jingwen; Wang, Yueming

    2016-08-01

    Mo coatings with or without incorporated MoSi2 were fabricated by atmospheric plasma spraying, and their microstructure, microhardness, bond strength, and wear resistance were compared. Two kinds of spray powder, i.e., pure Mo and a blend of Mo and MoSi2, were sprayed onto low-carbon steel. Microstructural analysis of the MoSi2-Mo coating showed MoSi2 homogeneously distributed in a Mo matrix. Addition of MoSi2 particles increased the microhardness of the as-sprayed Mo coating. The adhesion strength of the Mo coating was better than that of the MoSi2-Mo coating. Wear test results showed that the wear rate and friction coefficient of the two coatings increased with increasing load, and the friction coefficient of the MoSi2-Mo coating was lower than that of the Mo coating. The MoSi2-Mo composite coating exhibited better wear resistance than the Mo coating. The wear failure mechanisms of the two coatings were local plastic deformation, delamination, oxidation, and adhesion wear.

  18. Preparation of ZrC nano-particles reinforced amorphous carbon composite coating by atmospheric pressure chemical vapor deposition

    International Nuclear Information System (INIS)

    To eliminate cracks caused by thermal expansion mismatch between ZrC coating and carbon-carbon composites, a kind of ZrC/C composite coating was designed as an interlayer. The atmospheric pressure chemical vapor deposition was used as a method to achieve co-deposition of ZrC and C from ZrCl4-C3H6-H2-Ar source. Zirconium tetrachloride (ZrCl4) powder carrier was especially made to control accurately the flow rate. The microstructure of ZrC/C composite coating was studied using analytical techniques. ZrC/C coating shows same morphology as pyrolytic carbon. Transmission electron microscopy (TEM) shows ZrC grains with size of 10-50 nm embed in turbostratic carbon. The formation mechanism is that the growth of ZrC crystals was inhibited by surrounding pyrolytic carbon and kept as nano-particles. Fracture morphologies imply good combination between coating and substrate. The ZrC crystals have stoichiometric proportion near 1, with good crystalline but no clear preferred orientation while pyrolytic carbon is amorphous. The heating-up oxidation of ZrC/C coating shows 11.58 wt.% loss. It can be calculated that the coating consists of 74.04 wt.% ZrC and 25.96 wt.% pyrolytic carbon. The average density of the composite coating is 5.892 g/cm3 by Archimedes' principle.

  19. Fabrication of 5052Al/Al2O3 nanoceramic particle reinforced composite via friction stir processing route

    International Nuclear Information System (INIS)

    Highlights: → Introducing optimum FSP conditions for fabrication of a defect free SZ. → Fabrication of Al/Al2O3 nano-composite on surface of 5052 aluminum alloy. → Evaluation of microstructure and tensile properties of the composite and FSP zones. -- Abstract: In this research, microstructure and mechanical properties of 5052Al/Al2O3 surface composite fabricated by friction stir processing (FSP) and effect of different FSP pass on these properties were investigated. Two series of samples with and without powder were friction stir processed by one to four passes. Tensile test was used to evaluate mechanical properties of the composites and FSP zones. Also, microstructural observations were carried out using optical and scanning electron microscopes. Results showed that grain size of the stir zone decreased with increasing of FSP pass and the composite fabricated by four passes had submicron mean grain size. Also, increase in the FSP pass caused uniform distribution of Al2O3 particles in the matrix and fabrication of nano-composite after four passes with mean cluster size of 70 nm. Tensile test results indicated that tensile and yield strengths were higher and elongation was lower for composites fabricated by three and four passes in comparison to the friction stir processed materials produced without powder in the similar conditions and all FSP samples had higher elongation than base metal. In the best conditions, tensile strength and elongation of base material improved to 118% and 165% in composite fabricated by four passes respectively.

  20. Al2O3-Coated Nano-SiC Particles Reinforced Al2O3 Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Properties of Al2O3-coated nano-SiC have been compared with those of as-received SiC. The isoelectric point (IEP)of SiC changed from pH3.4 to pH7.3 after coating with the alumina precursor, which is close to that of alumina.Because both surfaces of coated SiC and Al2O3 possess higher positive charge at pH=4.5~5.0, they are uniformly dispersed in the two-phase aqueous suspensions, Then a mixed powder containing nano-SiC dispersed homogeneously into the Al2O3 matrix was achieved from flocculating the two-phase suspension. Finally, Al2O3/SiC nanocomposites were obtained by coating nano-SiC with Al2O3, in which the majority of SiC particles were located within the Al2O3 grains. The observation by transmission electron microscopy (TEM) and the analysis by the X-ray photoelectron spectroscopy (XPS) showed that cracks propagated towards the intragranular SiC rather than along grain boundaries.

  1. Energy Conservation/Waste Reduction in the Processing of Soft (Unfired) Ceramic Particles Via Dynamic Cyclone Classification

    Energy Technology Data Exchange (ETDEWEB)

    Wright, Steve R.

    2003-04-15

    The objective of this project was to advance the development of a novel inertial classifier technology to a full-scale industrial product by sequentially evaluating performance of pre-commercial prototypes. The technology, termed a ''Dynamic Cyclone Classifier'' (DCC), utilizes boundary layers on rotating annular disks to effect particle separation with minimal particle-rotor impaction. Although a large (2-ton/hr) DCC was originally envisioned for use within the mining industry, a smaller (kg/hr) sub-10-mm ''Fine Particle Dynamic Cyclone Classifier'' (FPDCC) was subsequently developed as a result of market research that showed higher commercialization potential for classifying ultrafine powders. Modified FPDCC prototypes were iteratively tested and evaluated in the sub-10-mm particle size range using standardized test particles (i.e., ISO Fine test dust). Classification performance tests were assessed by varying device parameters to define the operational envelope of the device to obtain sharp classification cuts, to maximize particle dispersion, to limit particle attrition and to increase production yields. The FPDCC exhibited sub-10-mm performance using both ideal (ISO test dust) and pharmaceutical excipient (calcium carbonate) ultrafine powders. Performance was compared with conventional classification technologies having the ability to process sub-10-mm ultrafine powders, specifically high-efficiency cyclones (HECs) and rotary vane classifiers (RVCs). The FPDCC can generate sharper classification cuts than high-pressure/high efficiency cyclones (HECs), since there is no turbulent particle re-entrainment, while using as much as 95% less energy. Being vaneless, particle impact with high RPM rotor components in the FPDCC is much less severe than in rotary vane classifiers (RVCs), leading to less critical component wear/erosion and concomitantly reducing potential product attrition and contamination. FPDCC energy usage is

  2. Synthesis, microstructural and mechanical properties of ex situ zircon particles (ZrSiO4 reinforced Metal Matrix Composites (MMCs: a review

    Directory of Open Access Journals (Sweden)

    Satish Kumar Thandalam

    2015-07-01

    This review article details the current development on the synthesis, microstructure and mechanical properties of zircon reinforced MMCs, with specific attention on the abrasive wear behavior of the composites. This review also summarizes the work done by various research groups on zircon reinforced MMCs in achieving higher hardness and wear resistance in these composites.

  3. Load partitioning in aluminum syntactic foams containing ceramic microspheres

    International Nuclear Information System (INIS)

    Syntactic foams were fabricated by pressure-infiltrating liquid aluminum (commercial purity and 7075-Al) into a packed preform of silica-mullite hollow microspheres. These foams were subjected to a series of uniaxial compression stresses while neutron or synchrotron X-ray diffraction measurements of elastic strains in the matrix and the microspheres were obtained. As for metal matrix composites with monolithic ceramic reinforcement, load transfer in the pure aluminum foams is apparent between the two phases during elastic deformation, and is affected at higher stresses by matrix plasticity. Calculating effective stresses from the lattice strains shows that the microspheres unload the pure aluminum matrix by a factor of about 2. In the aluminum alloy foams, an in situ reaction between silica and the melt leads to the conversion of silica to alumina in the microsphere walls and the precipitation of silicon particles in the matrix. This affects the load transfer between the matrix and the reinforcement (microspheres and particles), and increases the macroscopic foam stiffness by over 40%, as compared to the pure aluminum foams. Composite micromechanical modeling provides good predictions of the elastic moduli of the syntactic foams, capturing the effects of load transfer and suggesting that significant stiffness improvements can be achieved in syntactic foams by the use of microspheres with stiff walls and/or by the incorporation of a stiff reinforcing phase within the metallic matrix

  4. Metal/ceramic interface structures and segregation behavior in aluminum-based composites

    International Nuclear Information System (INIS)

    Trimodal Al alloy (AA) matrix composites consisting of ultrafine-grained (UFG) and coarse-grained (CG) Al phases and micron-sized B4C ceramic reinforcement particles exhibit combinations of strength and ductility that render them useful for potential applications in the aerospace, defense and automotive industries. Tailoring of microstructures with specific mechanical properties requires a detailed understanding of interfacial structures to enable strong interface bonding between ceramic reinforcement and metal matrix, and thereby allow for effective load transfer. Trimodal AA metal matrix composites typically show three characteristics that are noteworthy: nanocrystalline grains in the vicinity of the B4C reinforcement particles; Mg segregation at AA/B4C interfaces; and the presence of amorphous interfacial layers separating nanocrystalline grains from B4C particles. Interestingly, however, fundamental information related to the mechanisms responsible for these characteristics as well as information on local compositions and phases are absent in the current literature. In this study, we use high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy, and precession assisted electron diffraction to gain fundamental insight into the mechanisms that affect the characteristics of AA/B4C interfaces. Specifically, we determined interfacial structures, local composition and spatial distribution of the interfacial constituents. Near atomic resolution characterization revealed amorphous multilayers and a nanocrystalline region between Al phase and B4C reinforcement particles. The amorphous layers consist of nonstoichiometric AlxOy, while the nanocrystalline region is comprised of MgO nanograins. The experimental results are discussed in terms of the possible underlying mechanisms at AA/B4C interfaces

  5. Effect of Aluminium Content on the In-situ Synthesis of Nanocrystalline TiN Particles in Al-Ti-AlN Composite by Mechanical Alloying

    International Nuclear Information System (INIS)

    Aluminum matrix composites (AMCs) have gathered attention as new advanced materials due to their improved strength to weight ratio, a most desirable characteristic in automotive, aerospace and military industries [1]. Such materials offer a combination of light weight, high strength, and high specific modulus, low coefficient of thermal expansion; good wear resistance properties and beneficial physical behaviors like electrical and thermal conductivity [2]. When reinforced with ceramic particles, AMCs exhibit improved mechanical properties attractive to researchers for their potential structural applications [3]. Such ceramic particles include AlN [4] and TiN [5]. (author)

  6. Reinforcements for high temperature ceramics. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kyriacou, C.I.; Sepulveda, J.L.; Watson, M.A. [Keramont Corp., Tucson, AZ (United States)

    1992-04-01

    A method has been investigated and developed to grow TiB{sub 2} whiskers by the VLS mechanism. The reaction was carried out in a quartz tube 3 in. in diameter, 30 in. long at about 1150{degrees}C in the presence of a catalyst. The basic experimental parameters, a substrate, and a catalyst, for the growth of the whiskers have been defined. The whiskers produced have shown variable size and morphology depending on the experimental conditions, and location of the whiskers from the input port. The corrosion of the catalyst by the gas environment, and the gas distribution profile in the furnace had a serious effect on the reproducibility of the experimental results, and the overall yield of whiskers.

  7. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  8. Improving the strength of ceramics by controlling the interparticle forces and rheology of the ceramic suspensions

    CERN Document Server

    Chou, Y P

    2001-01-01

    This thesis describes a study of the modification of the interparticle forces of colloidal ceramic particles in aqueous suspensions in order to improve the microstructural homogeneity, and hence the reliability and mechanical performances, of subsequently formed ceramic compacts. A concentrated stable fine ceramic powder suspension has been shown to be able to generate a higher density of a ceramic product with better mechanical, and also electrical, electrochemical and optical, properties of the ceramic body. This is because in a colloidally stable suspension there are no aggregates and so defect formation, which is responsible for the ceramic body performance below its theoretical maximum, is reduced. In order to achieve this, it is necessary to form a well dispersed ceramic suspension by ensuring the interparticle forces between the particles are repulsive, with as a high a loading with particles as possible. By examining the rheological behaviour and the results of Atomic Force Microscope, the dispersion ...

  9. Reliability Estimation for Single-unit Ceramic Crown Restorations

    OpenAIRE

    Lekesiz, H.

    2014-01-01

    The objective of this study was to evaluate the potential of a survival prediction method for the assessment of ceramic dental restorations. For this purpose, fast-fracture and fatigue reliabilities for 2 bilayer (metal ceramic alloy core veneered with fluorapatite leucite glass-ceramic, d.Sign/d.Sign-67, by Ivoclar; glass-infiltrated alumina core veneered with feldspathic porcelain, VM7/In-Ceram Alumina, by Vita) and 3 monolithic (leucite-reinforced glass-ceramic, Empress, and ProCAD, by Ivo...

  10. Compound characterization of laser brazed SiC-steel joints using tungsten reinforced SnAgTi-alloys

    Science.gov (United States)

    Südmeyer, I.; Rohde, M.; Fürst, T.

    2010-02-01

    With the help of a CO2-laser (λ = 10.64 μm) Silicon carbide (Trade name: Ekasic-F, Comp: ESK Ceramics) has been brazed to commercial steel (C45E, Matnr. 1.1191) using SnAgTi-filler alloys. The braze pellets were dry pressed based on commercially available powders and polished to a thickness of 300 μm. The SnAgTi-fractions were varied with the objective of improving the compound strength. Furthermore, tungsten reinforced SnAgTi-fillers were examined with regard to the shear strength of the ceramic/steel joints. Polished microsections of SnAgTi-pellets were investigated before brazing in order to evaluate the particle distribution and to detect potential porosities using optical microscopy. The brazing temperature and the influence of the reinforcing particles on the active braze filler were determined by measurements with a differential scanning calorimeter (DSC). After brazing. the ceramic-steel joints were characterized by scanning electron micrographs and EDX-analysis. Finally the mechanical strength of the braze-joints was determined by shear tests.

  11. Effect of surface treatments on the bond strength of a zirconia-reinforced ceramic to composite resin Efeito de tratamentos de superfície sobre a resistência de união entre cerâmica reforçada por zircônia e resina composta

    Directory of Open Access Journals (Sweden)

    Alvaro Della Bona

    2007-03-01

    Full Text Available The objective of this study was to evaluate the tensile (sigmat and shear bond strength (sigmas of a glass-infiltrated alumina-based zirconia-reinforced ceramic (IZ - Vita In-Ceram Zirconia to a composite resin, testing the hypothesis that silica coating (SC - Cojet, 3M-Espe produces higher bond strength values than other ceramic surface treatments. Specimens were fabricated and tested according to the manufacturers' instructions, and to ISO6872 and ISO11405 specifications. Sixty IZ disk specimens were polished through 1 µm and divided into 3 groups (n = 20 according to the following surface treatments: HF - 9.5% hydrofluoric acid (Ultradent for 1 min; SB - sandblasting with 25-µm aluminum oxide particles for 10 s; SC - silica coating for 10 s. Silane (3M-Espe, adhesive (Single Bond, 3M-Espe and a composite resin cylinder (Z100, 3M-Espe were applied and polymerized to the treated bonding area (3.5 mm in diameter. Ten specimens from each group (n = 10 were tested for sigmat and ten specimens were tested for sigmas, using a universal testing machine (EMIC DL 2000 at a crosshead speed of 1 mm/min. The data were statistically analyzed by ANOVA and Tukey tests (alpha = 0.05. The mean and standard deviation values (MPa and statistical groupings for sigmat were: HF - 3.5 ± 1.0a; SB - 7.6 ± 1.2b; and SC - 10.4 ± 1.8c. For sigmas, the values were: HF - 10.4 ± 3.1A; SB - 13.9 ± 3.1B; and SC - 21.6 ± 1.7C (p O objetivo deste estudo foi avaliar a resistência adesiva à tração (sigmat e ao cisalhamento (sigmas de uma cerâmica à base de alumina infiltrada por vidro e reforçada com zircônia (IZ- Vita In-Ceram Zircônia à resina composta, testando a hipótese de que o sistema de silicatização (SC- Cojet, 3M-ESPE produz valores maiores de resistência adesiva do que demais tratamentos de superfície utilizados. Sessenta corpos-de-prova (cp em forma de disco da IZ foram fabricados e testados de acordo com as instruções dos fabricantes e as

  12. Ceramic Methyltrioxorhenium

    CERN Document Server

    Herrmann, R; Eickerling, G; Helbig, C; Hauf, C; Miller, R; Mayr, F; Krug von Nidda, H A; Scheidt, E W; Scherer, W; Herrmann, Rudolf; Troester, Klaus; Eickerling, Georg; Helbig, Christian; Hauf, Christoph; Miller, Robert; Mayr, Franz; Nidda, Hans-Albrecht Krug von; Scheidt, Ernst-Wilhelm; Scherer, Wolfgang

    2006-01-01

    The metal oxide polymeric methyltrioxorhenium [(CH3)xReO3] is an unique epresentative of a layered inherent conducting organometallic polymer which adopts the structural motifs of classical perovskites in two dimensions (2D) in form of methyl-deficient, corner-sharing ReO5(CH3) octahedra. In order to improve the characteristics of polymeric methyltrioxorhenium with respect to its physical properties and potential usage as an inherentconducting polymer we tried to optimise the synthetic routes of polymeric modifications of 1 to obtain a sintered ceramic material, denoted ceramic MTO. Ceramic MTO formed in a solvent-free synthesis via auto-polymerisation and subsequent sintering processing displays clearly different mechanical and physical properties from polymeric MTO synthesised in aqueous solution. Ceramic MTO is shown to display activated Re-C and Re=O bonds relative to MTO. These electronic and structural characteristics of ceramic MTO are also reflected by a different chemical reactivity compared with its...

  13. Synthesis and Characterization of SiC Reinforced HE-30 Al Alloy Particulate MMCs

    Directory of Open Access Journals (Sweden)

    Pradyumna Phutane

    2013-06-01

    Full Text Available Metal matrix composites have evoked a keen interest in recent times for potential applications in many areas, especially aerospace & automotive industries owing to their superior strength to weight ratio. A particle reinforced metal matrix composite consists of uniform distribution of strengthening ceramic particles embedded within metal matrix. Manufacturing of aluminum alloy based composites via stir casting is one of the prominent and economical routes for processing of metal matrix composites. An attempt has been made to synthesize HE-30 Al Alloy-SiC particulate metal matrix composite by liquid metallurgy route. Micro-structural characterization revealed fairly uniform distribution of SiC particles in the matrix. The prepared composite was subjected to the mechanical testing as per ASTM standards. The mechanical tests revealed an increase in hardness and tensile strength of the developed composites over the base metal alloy.

  14. Finite element analysis of Polymer reinforced CRC columns under close-in detonation

    DEFF Research Database (Denmark)

    Riisgaard, Benjamin

    2007-01-01

    Polymer reinforced Compact Reinforced Composite, PCRC, is a Fiber reinforced Densified Small Particle system, FDSP, combined with a high strength longitudinal flexural rebar arrangement laced together with polymer lacing to avoid shock initiated disintegration of the structural element under blast...

  15. Properties of textile grade ceramic fibers

    International Nuclear Information System (INIS)

    The availability of textile grade ceramic fibers has sparked great interest for applications in composite reinforcement and high temperature insulation. This paper summarizes the properties of various small diameter textile grade ceramic fibers currently available. Room temperature mechanical and electrical properties of the fibers are discussed for three cases: ambient conditions, after heat aging in argon, and after heat aging in wet air. Dow Corning (R) HPZ Ceramic Fiber, a silicon nitride type fiber, is shown to have improved retention of mechanical and electrical properties above 1200 C

  16. Fatigue-crack propagation behavior in monolithic and composite ceramics and intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Ritchie, R.O.; Dauskardt, R.H.; Venkateswara Rao, K.T. [Lawrence Berkeley Lab., CA (United States)

    1994-11-01

    We study microstructural mechanisms of fatigue crack growth in advanced monolithic and composite ceramics and intermetallics. Much attention is devoted to the contribution of cycling loading to the hindrance of mechanisms that lead to a considerable increase in toughness (crack-tip shielding) of these materials. For example, in intermetallics with a ductile phase, such as {Beta}-TiNb-reinforced {gamma}-TiAl or Nb-reinforced Nb{sub 3}Al, a significant increase in toughness caused by the presence of uncracked ductile phase inside a crack is retarded under cyclic loading because ductile particles immediately fail by fatigue. Similarly, in monolithic ceramics, e.g., in alumina (aluminum oxide) or silicon nitride, the significant plasticization appearing under monotonic loading is greatly diminished under cyclic loading due to gradual wear at the grain-matrix interface. In fact, the nature of fatigue in such low-plasticity materials differs essentially from the well-known mechanisms of fatigue in metals and is governed, first of all, by a decrease in shielding, which depends on the loading cycle and time. The susceptibility of intermetallics and ceramics to fatigue degradation under cyclic loading affects seriously the possibility of structural use of these materials in practice. In particular, in this case, it is difficult to apply strength calculation methods that take into account the presence of defects and to implement life-prediction procedures.

  17. Superplastic forming of ceramic insulation

    Science.gov (United States)

    Nieh, T. G.; Wittenauer, J. P.; Wadsworth, J.

    1992-01-01

    Superplasticity has been demonstrated in many fine-grained structural ceramics and ceramic composites, including yttria-stabilized tetragonal zirconia polycrystal (YTZP), alumina, and Al2O3-reinforced zirconia (Al2O3/YTZ) duplex composites and SiC-reinforced Si3N4. These superplastic ceramics obviously offer the potential benefit of forming net shape or near net shape parts. This could be particularly useful for forming complicated shapes that are difficult to achieve using conventional forming techniques, or require elaborate, subsequent machining. In the present study, we successfully demonstrated the following: (1) superplastic 3Y-TXP and 20 percent Al2O3/YTZ composite have for the first time been successfully deformed into hemispherical caps via a biaxial gas-pressure forming technique; (2) no experimental difficulty was encountered in applying the required gas pressures and temperatures to achieve the results, thus, it is certain that higher rates of deformation than those presented in this study will be possible by using the current test apparatus at higher temperatures and pressures; and (3) an analytical model incorporating material parameters, such as variations during forming in the strain rate sensitivity exponent and grain growth-induced strain hardening, is needed to model accurately and therefore precisely control the biaxial gas-pressure forming of superplastic ceramics. Based on the results of this study, we propose to fabricate zirconia insulation tubes by superplastic extrusion of zirconia polycrystal. This would not only reduce the cost, but also improve the reliability of the tube products.

  18. Repair of Cranial Bone Defects Using rhBMP2 and Submicron Particle of Biphasic Calcium Phosphate Ceramics with Through-Hole

    Directory of Open Access Journals (Sweden)

    Byung-Chul Jeong

    2015-01-01

    Full Text Available Recently a submicron particle of biphasic calcium phosphate ceramic (BCP with through-hole (donut-shaped BCP (d-BCP was developed for improving the osteoconductivity. This study was performed to examine the usefulness of d-BCP for the delivery of osteoinductive rhBMP2 and the effectiveness on cranial bone regeneration. The d-BCP was soaked in rhBMP2 solution and then freeze-dried. Scanning electron microscope (SEM, energy dispersive spectroscopy (EDS, and Raman spectroscopy analyses confirmed that rhBMP2 was well delivered onto the d-BCP surface and the through-hole. The bioactivity of the rhBMP2/d-BCP composite was validated in MC3T3-E1 cells as an in vitro model and in critical-sized cranial defects in C57BL/6 mice. When freeze-dried d-BCPs with rhBMP2 were placed in transwell inserts and suspended above MC3T3-E1, alkaline phosphatase activity and osteoblast-specific gene expression were increased compared to non-rhBMP2-containing d-BCPs. For evaluating in vivo effectiveness, freeze-dried d-BCPs with or without rhBMP2 were implanted into critical-sized cranial defects. Microcomputed tomography and histologic analysis showed that rhBMP2-containing d-BCPs significantly enhanced cranial bone regeneration compared to non-rhBMP2-containing control. These results suggest that a combination of d-BCP and rhBMP2 can accelerate bone regeneration, and this could be used to develop therapeutic strategies in hard tissue healing.

  19. The influence of reinforcement shape on wear behaviour of aluminium matrix composite materials

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2010-09-01

    Full Text Available urpose: The purpose of this paper is to present the research results of modern metal matrix composite materials. The matrix material was EN AC - AlSi12 alloy while the reinforcement ceramic performs. In order to investigate the influence of reinforcing phase’s shape on tribological properties the comparison was made between the composite material based on preforms obtained by Al2O3 Alcoa CL 2500 powder sintered with addition of pore forming agent in form of carbon fibres Sigrafil C 10 M250 UNS from Carbon Group company and composite materials based on much more expensive commercial fibrous preforms.Design/methodology/approach: The composite was produced by the use of porous material pressure infiltration method. Obtained composite materials were examined with light and scanning electron microscopy. Hardness test was carried out with Rockwell method in A scale. Additionally, the wear resistance was measured by the use of device designed in the Institute of Engineering Materials and Biomaterials. The device realize dry friction wear mechanism of reciprocating movement conditions.Findings: The obtained results show the possibility of manufacturing the new composite materials by the method of porous sintered framework pressure infiltration based on the ceramic particles, with desired microstructure and properties, being a cheaper alternative for materials with base of ceramic fibers.Practical implications: Tested composite materials can be apply among the others in automotive and aircraft industries.Originality/value: Worked out technology of composite materials manufacturing can be used in the production of near net shape and locally reinforced elements

  20. Engineering ceramics

    CERN Document Server

    Bengisu, Murat

    2001-01-01

    This is a comprehensive book applying especially to junior and senior engineering students pursuing Materials Science/ Engineering, Ceramic Engineering and Mechanical Engineering degrees. It is also a reference book for other disciplines such as Chemical Engineering, Biomedical Engineering, Nuclear Engineering and Environmental Engineering. Important properties of most engineering ceramics are given in detailed tables. Many current and possible applications of engineering ceramics are described, which can be used as a guide for materials selection and for potential future research. While covering all relevant information regarding raw materials, processing properties, characterization and applications of engineering ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  1. Ceramic glossary

    International Nuclear Information System (INIS)

    This book is a 2nd edition that contains new terms reflecting advances in high technology applications of ceramic materials. Definitions for terms which materials scientists, engineers, and technicians need to know are included

  2. Tailored ceramics

    International Nuclear Information System (INIS)

    In polyphase tailored ceramic forms two distinct modes of radionuclide immobilization occur. At high waste loadings the radionuclides are distributed through most of the ceramic phases in dilute solid solution, as indicated schematically in this paper. However, in the case of low waste loadings, or a high loading of a waste with low radionuclide content, the ceramic can be designed with only selected phases containing the radionuclides. The remaining material forms nonradioactive phases which provide a degree of physical microstructural isolation. The research and development work with polyphase ceramic nuclear waste forms over the past ten years is discussed. It has demonstrated the critical attributes which suggest them as a waste form for future HLW disposal. From a safety standpoint, the crystalline phases in the ceramic waste forms offer the potential for demonstrable chemical durability in immobilizing the long-lived radionuclides in a geologic environment. With continued experimental research on pure phases, analysis of mineral analogue behavior in geochemical environments, and the study of radiation effects, realistic predictive models for waste form behavior over geologic time scales are feasible. The ceramic forms extend the degree of freedom for the economic optimization of the waste disposal system

  3. Metallic and intermetallic-bonded ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    The purpose of this task is to establish a framework for the development and fabrication of metallic-phase-reinforced ceramic matrix composites with improved fracture toughness and damage resistance. The incorporation of metallic phases that plastically deform in the crack tip region, and thus dissipate strain energy, will result in an increase in the fracture toughness of the composite as compared to the monolithic ceramic. It is intended that these reinforced ceramic matrix composites will be used over a temperature range from 20{degrees}C to 800-1200{degrees}C for advanced applications in the industrial sector. In order to systematically develop these materials, a combination of experimental and theoretical studies must be undertaken.

  4. Numerical investigation of the stress field near a crack normal to ceramic.metal interface

    International Nuclear Information System (INIS)

    Ceramic.metal interfaces are often present in composite materials. The presence of cracks has a major impact on the reliability of advanced materials, such as fiber or particle reinforced ceramic composites, ceramic interfaces and laminated ceramics. The understanding of the failure mechanisms is very important, as is as the estimation of fracture parameters at the tip of the crack approaching an interface and crack propagation path. A cracked sandwich plate loaded with axial uniform normal stress was numerically investigated using plane strain Finite Element Analysis. The numerical results for the singularity orders were compared with the analytical solution. The influences of the material combination and crack length on the radial and circumferential stresses and displacement distributions were investigated. The Stress Intensity Factors were determined based on numerical results using a displacement extrapolation method. The results for the non-dimensional stress intensity factors show that at lower crack lengths the influence of material mismatch is lower, but this influence increases with increasing crack length

  5. REINFORCED COMPOSITE PANEL

    DEFF Research Database (Denmark)

    2003-01-01

    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing...... matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

  6. Influence of ceramic particulate type on microstructure and tensile strength of aluminum matrix composites produced using friction stir processing

    Directory of Open Access Journals (Sweden)

    I. Dinaharan

    2016-06-01

    Full Text Available Friction stir processing (FSP was applied to produce aluminum matrix composites (AMCs. Aluminum alloy AA6082 was used as the matrix material. Various ceramic particles, such as SiC, Al2O3, TiC, B4C and WC, were used as reinforcement particle. AA6082 AMCs were produced using a set of optimized process parameters. The microstructure was studied using optical microscopy, filed emission scanning electron microscopy and electron back scattered diagram. The results indicated that the type of ceramic particle did not considerably vary the microstructure and ultimate tensile strength (UTS. Each type of ceramic particle provided a homogeneous dispersion in the stir zone irrespective of the location and good interfacial bonding. Nevertheless, AA6082/TiC AMC exhibited superior hardness and wear resistance compared to other AMCs produced in this work under the same set of experimental conditions. The strengthening mechanisms and the variation in the properties are correlated to the observed microstructure. The details of fracture mode are further presented.

  7. Effect of ageing on the mechanical behaviour of aluminium alloy AA2009 reinforced with SIC particles; Influencia del estado de envejecimiento en el comportamiento mecanico de una aleacion de aluminio AA2009 reforzada con particulas de SiC

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigo, P.; Poza, P.; Utrilla, M. v.; Urena, A.

    2005-07-01

    A study of the mechanical behaviour of an aluminium matrix composite (AA2009) reinforced with 15 volume percent of SiC particles has been carried out. The ageing kinetic for this material has been evaluated at two different ageing temperatures (170 and 190 degree centigree). The hardness peaks for the two different precipitation sequences existing in the matrix alloy have been identified. The mechanical behaviour of the composite was also evaluated for the different thermal conditions (as-received and aged). This research has been completed with the identification of the fracture mechanisms by means of observation with scanning electron microscopy (SEM) both of the fracture surface and transversal sections of them. In addition, transmission electron microscopy (TEM) of the treated composites has been used to determine the influence of the SiC particles on the distribution of strengthening phases precipitated in the matrix. (Author) 14 refs.

  8. Basal Reinforced Piled Embankments

    NARCIS (Netherlands)

    Van Eekelen, S.J.M.

    2015-01-01

    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal reinforce

  9. 多层喷射沉积颗粒增强铝基复合材料的研究现状与发展趋势%Current State and Developing Trends of Multiinlayer Spray Deposited Aluminium Matrix Composites Reinforced with Particles

    Institute of Scientific and Technical Information of China (English)

    贺毅强; 陈志钢

    2012-01-01

    Multi-layer spray deposition technology employed to make particle reinforced aluminum matrix composites can promote the effect of fast cooling, refine and homogenize microstructure, narrow the particle size distribution and optimize the particles and matrix bonding. In this paper, the current situations of R~D of spray deposited aluminum matrix composites, the principles and processing parameters of multi-layer spray deposition are reviewed. The developments of spray deposited A1-Zn-Mg, A1-Fe and A1-Si matrix composites are summarized. Densification methods for spray deposited aluminum matrix composites, especially novel methods including wedge pressing, cage rolling, ceramics rolling, and hot pressing for bulk preform compacted on a light tonnage equipment are emphasized. Developing trends of multi-layer spray deposited aluminum matrix composites are also presented. It is Considered that the bonding of the interface between the reinforcement particles and the aluminum matrix needs to be optimized. Multi-layer spray deposition has been invented to preparing bulk parts with uniform and high density in a programmable control. Densifieation methods are also developed towards light tonnage compact bulk preform. And the forming ability of the bulk deposits can be enhanced effectively by hot and wedge pressing, and then benefitting the deformation in next step.%通过多层喷射沉积技术制备颗粒增强铝基复合材料,强化了冷却效果,能获得细小均匀的显微组织,优化复合材料中增强相的分布及其与基体的结合状态。本文综述了喷射沉积颗粒增强铝基复合材料的发展现状;介绍了多层喷射沉积技术的原理与工艺参数;概述了喷射沉积颗粒增强Al-Zn—Mg系、Al—Fe系与Al-Si系复合材料;并介绍喷射沉积颗粒增强铝基复合材料的致密化技术,着重介绍在小吨位设备上致密大块多孔材料的楔形压制工艺、外框限制轧制、陶粒包覆轧制工

  10. Process of producing a ceramic matrix composite article and article formed thereby

    Science.gov (United States)

    Corman, Gregory Scot; McGuigan, Henry Charles; Brun, Milivoj Konstantin

    2011-10-25

    A CMC article and process for producing the article to have a layer on its surface that protects a reinforcement material within the article from damage. The method entails providing a body containing a ceramic reinforcement material in a matrix material that contains a precursor of a ceramic matrix material. A fraction of the reinforcement material is present and possibly exposed at a surface of the body. The body surface is then provided with a surface layer formed of a slurry containing a particulate material but lacking the reinforcement material of the body. The body and surface layer are heated to form the article by converting the precursor within the body to form the ceramic matrix material in which the reinforcement material is contained, and by converting the surface layer to form the protective layer that covers any fraction of the reinforcement material exposed at the body surface.

  11. Fracture Resistance Evaluation of Fibre Reinforced Brittle Matrix Composites

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk

    2005-01-01

    Roč. 290, - (2005), s. 167-174. ISSN 1013-9826. [Fractography of Advanced Ceramic s /2./. Stará Lesná, 03.10.2004-06.10.2004] R&D Projects: GA AV ČR(CZ) IAA2041003; GA ČR(CZ) GA101/02/0683 Keywords : fibre-reinforced ceramic s * glass matrix composites * chevron notch Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.224, year: 2005

  12. Fracture Resistance Evaluation of Fibre Reinforced Brittle Matrix Composites

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Chlup, Zdeněk

    2004, s. -. [Fractography of Advanced Ceramic s. Stará Lesná (SK), 03.10.2004-06.10.2004] R&D Projects: GA AV ČR IAA2041003; GA ČR GA101/02/0683 Institutional research plan: CEZ:AV0Z2041904 Keywords : fibre-reinforced ceramic s * glass matrix composites * chevron notch Subject RIV: JL - Materials Fatigue, Friction Mechanics

  13. Processes for fabricating composite reinforced material

    Energy Technology Data Exchange (ETDEWEB)

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2015-11-24

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  14. Effect of Ceramic Thickness and Luting Agent Shade on the Color Masking Ability of Laminate Veneers

    OpenAIRE

    Begum, Zubeda; Chheda, Pratik; Shruthi, C. S.; Sonika, Radhika

    2014-01-01

    The main objective of the study was to recognize the effect of ceramic thickness and luting agent on the extent to which the restoration masks color variations that may be present in the underlying dental structure. Two pressable ceramics were used: Lithium disilicate reinforced (IPS e.max- Ivoclar Vivadent) and Leucite reinforced (Cergo- Dentsply). Fifteen ceramic discs were manufactured from each ceramic and divided into three groups, according to the thickness (0.5, 1, 1.5 mm). To simulate...

  15. Recycled ABS Resin Toughened and Reinforced by Elastomer/Inorganic Nano-Particle Composite System%弹性体/无机纳米粒子复合体系增强增韧回收ABS树脂

    Institute of Scientific and Technical Information of China (English)

    孔雪松

    2013-01-01

    The toughening of elastomer and inorganic nano-particle to recycled ABS was studied respectively.The results show that elastomer restores the toughness of recycles ABS,but leads to decrease of rigidity,meanwhile inorganic nano-particle can increase the toughness partly,also leads to increases of rigidity.Finally recycled ABS is modified by elastomer/inorganic nano-particle composite system.When 5%~8% ABS rubber powder and 2% ~3% inorganic particle are added,the recycled ABS resin is toughened and reinforced.%分别研究了弹性体和无机纳米粒子对回收丙烯腈-丁二烯-苯乙烯共聚物(ABS)的增韧.结果表明:弹性体能使回收ABS树脂的韧性得到恢复,但导致刚性下降;无机纳米粒子对ABS树脂的增韧能力有限,但能增加ABS的刚性.最后采用弹性体/无机纳米粒子复合体系改性回收ABS树脂,添加质量分数5%~8%的高胶粉和质量分数2%~3%无机纳米粒子时,实现了对回收ABS树脂的增强增韧.

  16. Habituation of reinforcer effectiveness

    OpenAIRE

    Lloyd, David R; Hawk, Larry W.

    2014-01-01

    In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE) is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We ar...

  17. Thermal shock resistant ceramic insulator

    International Nuclear Information System (INIS)

    A specification is given for thermal shock resistant cermet insulators which contain 0.1 to 20 volume % metal present as a dispersed phase. They are prepared by (a) providing a first solid phase mixture of a ceramic powder and a metal precursor; (b) heating the first solid phase mixture above the minimum decomposition temperature of the metal precursor for no longer than 30 minutes and to a temperature sufficiently above the decomposition temperature to cause the selective decomposition of the metal precursor to the metal to provide a second solid phase mixture comprising particles of ceramic having discrete metal particles adhering to their surfaces, the metal particles having a mean diameter no more than 1/2 the mean diameter of the ceramic particles, and (c) densifying the second solid phase mixture to provide the desired cermet insulator. Examples of the ceramics include BN, B4C, ZrO2, WO3, BeO, Y2O3, TaO, the lanthanide oxides, the oxides of uranium, the oxides of thorium, the oxides of niobium. Examples of the metal precursor include TaHsub(0.5), UH3, ZrH2, ThH2, W(CO)6, ReCl3, WO3 MoO3. (author)

  18. Transverse Reinforcement in Reinforced Concrete Columns

    Science.gov (United States)

    Gramblička, Štefan; Veróny, Peter

    2013-11-01

    In the article we are dealing with the influence of transverse reinforcement to the resistance of a cross-section of the reinforced concrete columns and also with the effective detailing of the column reinforcement. We are verifying the correctness of design guides for detailing of transverse reinforcement. We are also taking into account the diameter of stirrups and its influence over transverse deformation of column.

  19. Tribological properties of aluminium matrix composites reinforcement with intermetallic phases

    Directory of Open Access Journals (Sweden)

    J. Wieczorek

    2006-02-01

    Full Text Available Purpose: In the investigations, two types of material were taken for the cooperation with the composite Al + intermetallic phases. One of the materials were composites based on the AlMg12Si alloy, reinforced with ceramic particles (SiC, Al2O3, and the other was spheroidal cast iron.Design/methodology/approach: For the investigations of wear under technically dry friction conditions the pin-on-disc measuring system was applied.Findings: It has been shown that Al based composites reinforced with intermetallic phases are characterized by considerable resistance to tribological wear under technically dry friction conditions in a cooperation with composites based on the Al alloy (AlSi12CuNiMg . The tribological systems in which composites of the Al +intermetallic phases type are used, are characterized by a stable course of the friction coefficient value as a function of friction distance, irrespective of the type of material cooperating with them.Practical implications: In the case of cooperation of Al-Al2O3-Al3Ti-Al3Fe composites with aluminium alloy based composites, one should take into account the changes in friction conditions resulting from plastic deformation of the friction surface of the composite Al + intermetallic phases.Originality/value: Thanks to conducted researches it was stated that there is a possibilty of application of heterophase reinforcement that use the mixture of intermetalic phases as a effective method of aluminium alloys resistance improving the wear in dry sliding conditions.

  20. Recycling and reuse of waste from electricity distribution networks as reinforcement agents in polymeric composites.

    Science.gov (United States)

    Zimmermann, Matheus V G; Zattera, Ademir J

    2013-07-01

    Of the waste generated from electricity distribution networks, wooden posts treated with chromated copper arsenate (CCA) and ceramic insulators make up the majority of the materials for which no effective recycling scheme has been developed. This study aims to recycle and reuse this waste as reinforcement elements in polymer composites and hybrid composites, promoting an ecologically and economically viable alternative for the disposal of this waste. The CCA wooden posts were cut, crushed and recycled via acid leaching using 0.2 and 0.4N H2SO4 in triplicate at 70°C and then washed and dried. The ceramic insulators were fragmented in a hydraulic press and separated by particle size using a vibrating sieve. The composites were mixed in a twin-screw extruder and injected into the test specimens, which were subjected to physical, mechanical, thermal and morphological characterization. The results indicate that the acid treatment most effective for removing heavy metals in the wood utilizes 0.4NH2SO4. However, the composites made from wood treated with 0.2NH2SO4 exhibited the highest mechanical properties of the composites, whereas the use of a ceramic insulator produces composites with better thermal stability and impact strength. This study is part of the research and development project of ANEEL (Agência Nacional de Energia Elétrica) and funded by CPFL (Companhia Paulista de Força e Luz). PMID:23663959

  1. Hybrid Ti-ceramic bionanomaterials for medical engineering

    Energy Technology Data Exchange (ETDEWEB)

    Niespodziana, K.; Miklaszewski, A.; Jurczyk, M. [Institute of Materials Science and Engineering, Poznan University of Technology, Sklodowska-Curie 5 Sq., 60-965 Poznan (Poland); Jurczyk, K. [Department of Conservative Dentistry and Periodontology, University of Medical Sciences, Bukowska 70 St., 60-812 Poznan (Poland)

    2010-05-15

    In the last decade a great interest has been observed in the field of nanoscale materials. Commercially pure titanium as well as titanium alloys have become predominant in implantology. Low hardness and poor tribiological properties of titanium alloys may become critical factor when wear phenomena are involved. One of the methods that allow the change of properties of Ti alloys is the production of nanocomposites, which will exhibit the favorable mechanical properties of titanium and excellent biocompatibility and bioactivity of ceramics. In this work hybrid Ti-x wt% ceramic (45S5 Bioglass, SiO{sub 2}, Al{sub 2}O{sub 3}) bionanocomposites (x =0, 3 and 10) were prod-uced by the combination of mechanical alloying and powder metallurgical process. Reinforced by 45S5 Bioglass, SiO{sub 2} or Al{sub 2}O{sub 3} particles, Vickers hardness of Ti-based nanocomposite is higher from two to six times in comparison with pure microcrystalline Ti. Additionally, the experimental results show that in Ringer's solution at 37 C, Ti-based nanocomposites have good corrosion resistance. On the other hand, in vitro studies show that these bionanocomposites have excellent biocompatibility and could integrate with bone (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. 无压浸渗法制备氧化态SiC颗粒增强铝基复合材料%Fabrication of Oxidized SiC Particles Reinforced Aluminum Matrix Composite by Pressureless Infiltration Technique

    Institute of Scientific and Technical Information of China (English)

    张强; 姜龙涛; 武高辉

    2012-01-01

    The oxidation behavior of SiC particles in the temperature range from l000℃ to 1200℃ was investi-gated. The dependence of weight gain and oxidation time was parabolic and the oxidation behavior was controlled by diffusion process, with a oxidation activation energy of 219 kJ/mol. Using oxidized SiC particles as reinforce-ment and aluminum alloy containing Si and Mg as matrix, a SiCp/Al composite was fabricated by pressureless infil-tration technique. The microstructure and interfacial morphology were analyzed and the pressureless infiltration mechanisms were discussed. The particles were distributed uniformly in the composite, without particles agglom-eration. Interfacial reactions were found in the composite and the product was identified as MgAl2O4, formed by the reactions between surface oxide layer of SiC particles and Mg, Al in the matrix. The interfacial reactions enhanced the wettability and promoted the spontaneous infiltration process.%研究了SiC颗粒在1000~1200℃的氧化行为,其氧化增重率与保温时间符合抛物线规律,氧化增重受扩散过程控制,氧化激活能为219 kJ/mol.采用预氧化处理的SiC颗粒为增强体,含Si、Mg的铝合金为基体,通过无压浸渗方法制备了SiCp/Al复合材料,分析了复合材料的微观组织与界面形貌,探讨了无压浸渗机理.复合材料中颗粒分布均匀,无偏聚现象.材料制备过程中存在界面反应,SiC颗粒表面的氧化层与铝合金中的Mg、Al反应形成了一定数量的MgAl2O4.界面反应的存在提高了润湿性,促进了无压自发浸渗.

  3. Fretting wear damage-I: numerical study of composite steel sheets reinforced with TiB2

    Directory of Open Access Journals (Sweden)

    F. Ayari

    2011-09-01

    Full Text Available Purpose: of this paper is based on the damage analysis by fretting wearing occurred on the composite steel sheets reinforced with TiB2 ceramic particles. There is a real lack to find a reliable data and detail research in literature that makes the purpose of this manuscript.Design/methodology/approach: Fretting is a surface degradation process in which removal of material is induced by small amplitude oscillatory movement between contacting components, such as flexible coupling joint structures etc. The main parameters affecting fretting wear are reported to be normal load, slip amplitude, frequency of the oscillatory movement, contact geometry, surface roughness and material properties. In this study, a finite element-based method is presented for simulating the contact of a rigid cylinder on flat fretting wear for the composite steel sheets reinforced with TiB2 ceramic particles.Findings: The general purpose commercial code ABAQUS was employed; this model can be used to facilitate generalization of the present approach to more complex applications. In this study a particular mesh technique was used to optimize the computation time, especially when dynamic analysis is used. In fact, two-dimensional, four-node, plane strain (linear elements are employed throughout. The mesh (element size in the contact area is very fine to capture the complicated variation of the surface and subsurface stresses and relative slip. The contact surface is constituted with a rigid hard steel cylinder material and a flat plate of composite steel sheets reinforced with TiB2 ceramic particles.Practical implications: This manuscript concerns a typical contact with the cylindrical plan geometry as it models the major problems and also stress distribution due to the contact was well defined. Our assembly is then, composed with a cylindrical contact with a plan substrate. An elastic - plastic analysis of fretting stress using a finite element ABAQUS is enhanced. The

  4. Fabrication of transparent ceramics using nanoparticles

    Science.gov (United States)

    Cherepy, Nerine J; Tillotson, Thomas M; Kuntz, Joshua D; Payne, Stephen A

    2012-09-18

    A method of fabrication of a transparent ceramic using nanoparticles synthesized via organic acid complexation-combustion includes providing metal salts, dissolving said metal salts to produce an aqueous salt solution, adding an organic chelating agent to produce a complexed-metal sol, heating said complexed-metal sol to produce a gel, drying said gel to produce a powder, combusting said powder to produce nano-particles, calcining said nano-particles to produce oxide nano-particles, forming said oxide nano-particles into a green body, and sintering said green body to produce the transparent ceramic.

  5. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.;

    2004-01-01

    scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from a...... viscoclastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel. (C) 2004 Elsevier Ltd. All rights reserved.......The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order to...

  6. Preparation of in situ and ex situ reinforced Fe-10Cr-1Cu-1Ni-1Mo-2C containing NbC particles by milling and hot pressing

    Science.gov (United States)

    Li, Xiao-qiang; Li, Zi-yang; Ye, Yong-quan; Hu, Ke

    2015-02-01

    An in situ and ex situ reinforced powder metallurgy (PM) steel was prepared by the combination of high-energy ball milling and subsequent hot pressing of elemental mixed powders of Fe-10Cr-1Cu-1Ni-1Mo-2C by mass with the addition of NbC particles. A 40-h milling pretreatment makes the powder particles nearly equiaxed with an average diameter of ˜8 μm, and the ferrite grain size is refined to ˜6 nm. The sintered density reaches 99.0%-99.7% of the theoretical value when the sintering is conducted at temperatures greater than 1000°C for 30 min. In the sintered bulk specimens, the formation of an in situ M7C3 (M = Cr, Fe, Mo) phase is confirmed. M7C3 carbides with several hundred nanometers in size are uniformly distributed in the matrix. Some ultra-fine second phases of 50-200 nm form around the ex situ NbC and in situ M7C3 particles. The sintered steel exhibits an excellent combination of hardness (> Hv 500) and compressive strength (2100-2420 MPa).

  7. Industrial ceramics

    International Nuclear Information System (INIS)

    After having given the definition of the term 'ceramics', the author describes the different manufacturing processes of these compounds. These materials are particularly used in the fields of 1)petroleum industry (in primary and secondary reforming units, in carbon black reactors and ethylene furnaces). 2)nuclear industry (for instance UO2 and PuO2 as fuels; SiC for encapsulation; boron carbides for control systems..)

  8. Role of Intergranular Films in Toughened Ceramics

    International Nuclear Information System (INIS)

    Self-reinforced silicon nitride ceramics rely the generation of elongated grains that act as reinforcing elements to gain increases in fracture toughness. However, the size and number of the reinforcing grains must be controlled, along with the matrix grain size, to optimize the fracture toughness and strength. Furthermore, the toughening processes of crack bridging are dependent upon retention of these reinforcing grains during crack extension by an interfacial debonding process. Both the debonding process and the resultant toughening effects are found to be influenced by the composition of the sintering aids which typical are incorporated into the amorphous intergranular films found in these ceramics. Specifically, it is shown that the interface between the intergranular glass and the reinforcing grains is strengthened in the presence of an epitaxial SiAlON layer. In addition, the interface strength increases with the Al and 0 content of the SiAlON layer. Micromechanics modeling indicates that stresses associated with thermal expansion mismatch are a secondary factor in interfacial debonding in these specific systems. On the other hand, first principles atomic cluster calculations reveal that the debonding behavior is consistent with the formation of strong Si-0 and Al-O bonds across the glass-crystalline interface

  9. Comparison of fracture toughness measuring methods applied on silicon nitride ceramics

    OpenAIRE

    RudnayovÁ, E.; Dusza, J.; KupkovÁ, M.

    1993-01-01

    Different fracture toughness testing methods on unreinforced and with Si3N4 whiskers reinforced silicon nitride ceramics were compared. The results revealed that in the reinforced ceramics the KIC rises with the increasing of the crack size, which indicates a rising R-curve behaviour in this system. Using IF testing method equations given by Niihara and by Shetty proved to have the nearest values to these achieved using SENB in both investigated systems.

  10. The compression strength investigations of AW-AlCu4Mg2Mn alloy based composites reinforced with SiC particles

    Directory of Open Access Journals (Sweden)

    A. Kurzawa

    2011-04-01

    Full Text Available In this paper strength tests of composite materials based on AW-AlCu4Mg2Mn obtained in uniaxial compression test was studied.Materials used for examination were made from AW-AlCu4Mg2Mn alloy and porous preforms of SiC particles (grain size 6÷10μm bypressure infiltration (squeeze casting. The stress-strain curves of the materials with 10% vol., 20% vol., 30% vol. particles of SiC, as well unreinforcement alloy and microstructure of scrap surface samples in a plane parallel to the compressive force were analyzed. The investigated metal matrix composites are characterized by marked reduced the plastic strain values with increasing particle strengthening while the unreinforcement materials throughout the range of deformation show considerable plasticity. In the case of the material containing 10% vol of SiC the plastic strain is a slight strengthening of the material. With increasing of the particle content the plasticity decreases. Materials with 20%vol and 30%vol of SiC particles were brittle cracked at much higher values of stress σ.

  11. Dual-nanoparticulate-reinforced aluminum matrix composite materials

    Science.gov (United States)

    Kwon, Hansang; Cho, Seungchan; Leparoux, Marc; Kawasaki, Akira

    2012-06-01

    Aluminum (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nano-SiC) were fabricated by mechanical ball milling, followed by hot-pressing. Nano-SiC was used as an active mixing agent for dispersing the CNTs in the Al powder. The hardness of the produced composites was dramatically increased, up to eight times higher than bulk pure Al, by increasing the amount of nano-SiC particles. A small quantity of aluminum carbide (Al4C3) was observed by TEM analysis and quantified using x-ray diffraction. The composite with the highest hardness values contained some nanosized Al4C3. Along with the CNT and the nano-SiC, Al4C3 also seemed to play a role in the enhanced hardness of the composites. The high energy milling process seems to lead to a homogeneous dispersion of the high aspect ratio CNTs, and of the nearly spherical nano-SiC particles in the Al matrix. This powder metallurgical approach could also be applied to other nanoreinforced composites, such as ceramics or complex matrix materials.

  12. Material Properties for Fiber-Reinforced Silica Aerogels

    Science.gov (United States)

    White, Susan; Rouanet, Stephane; Moses, John; Arnold, James O. (Technical Monitor)

    1994-01-01

    Ceramic fiber-reinforced silica aerogels are novel materials for high performance insulation, including thermal protection materials. Experimental data are presented for the thermal and mechanical properties, showing the trends exhibited over a range of fiber loadings and silica aerogel densities. Test results are compared to that of unreinforced bulk aerogels.

  13. Effect of the percentage of reinforcement on the wear in the metal matrix composites sintered with abnormal glow discharge

    International Nuclear Information System (INIS)

    In this study an analysis of the behavior of dry wear coefficient of a Metal Matrix Composite (MMC) in 316 stainless steel reinforced with particles of titanium carbide (TiC) according to ASTM G 99 standards, in a pin-on-disk test. In this research it is tested the effect of the percentage of reinforcement in the MMC manufactured with 3, 6 y 9% (vol.) of TiC, in samples compacted at 800 MPa, generating different values of grain size, hardness and density, they are sintered with abnormal glow discharge, at a temperature of 1200 degree centigrade ±5 degree centigrade, with a protection atmosphere H2 - N2 and a permanence time of 30 minutes. According to the results obtained it is concluded that the best condition for the MMC manufacturing, in relation to the reinforcement percentage, is the one obtained when the mixture contains 6% of TiC compacted at 800 MPa. In these conditions, it was obtained: achieving smaller grain size, the greater hardness and the lowest coefficient of friction. In this respect, it was observed that the incorporation of the ceramic particles (TiC) in a matrix of austenitic steel (316) shows significant improvements in the resistance to the wear. (Author)

  14. Thermal Expansion of Sintered Glass Ceramics in the System BaO-SrO-ZnO-SiO2 and Its Dependence on Particle Size.

    Science.gov (United States)

    Thieme, Christian; Schlesier, Martin; Bocker, Christian; Buzatto de Souza, Gabriel; Rüssel, Christian

    2016-08-10

    The thermal expansion behavior of sintered glass-ceramics containing high concentrations of Ba1-xSrxZn2Si2O7, a phase with very low and highly anisotropic thermal expansion behavior, was investigated. The observed phase has the crystal structure of the high-temperature phase of BaZn2Si2O7, which can be stabilized by the introduction of Sr(2+) into this phase. The high anisotropy leads to microcracking within the volume of the samples, which strongly affects the dilatometric thermal expansion. However, these cracks also have an influence on the nominal thermal expansion of the as-mentioned phase, which decreases if the cracks appear. Below a grain size of approximately 80 μm, the sintered glass-ceramics have almost no cracks and show positive thermal expansion. Hence, coefficients of thermal expansion between -5.6 and 6.5 × 10(-6) K(-1) were measured. In addition to dilatometric studies, the effect of the microstructure on the thermal expansion was also measured using in situ X-ray diffraction at temperatures up to 1000 °C. PMID:27433854

  15. Impact Behavior of Three Notched All-Ceramic Restorations after Soaking in Artificial Saliva

    OpenAIRE

    Min Yan; Chung-Kai Wei; Yuh-Yih Lin; Suh-Woan Hu; Shinn-Jyh Ding

    2015-01-01

    Biomechanics play a critical role in influencing the clinical applications of all-ceramic dental restorations. The restorative biomaterials have to demonstrate mechanical durability in the oral environment because they are always exposed to a variety of oral environments. This study was designed to evaluate the effect of soaking time, notch and saliva pH values on the impact energy of three commonly used all-ceramic materials for CAD/CAM. The leucite-reinforced glass ceramic (ProCAD), lithiu...

  16. CAD/CAM fabricated single-unit all-ceramic post–core–crown restoration

    OpenAIRE

    Thilla Sekar Vinothkumar; Deivanayagam Kandaswamy; Pallavi Chanana

    2011-01-01

    This case report explains about an innovative treatment strategy for the management of damaged anterior teeth with reduced incisal clearance by means of a single-unit all-ceramic post-core-crown zirconia ceramic restoration fabricated by Computer-aided designing and computer-aided manufacturing (CAD/CAM) technology. The reinforced zirconia ceramics allow fabrication of durable esthetic restorations in cases with high functional loading and the unification of the post, core, and crown in a sin...

  17. Monolithic ceramics

    Science.gov (United States)

    Herbell, Thomas P.; Sanders, William A.

    1992-01-01

    A development history and current development status evaluation are presented for SiC and Si3N4 monolithic ceramics. In the absence of widely sought improvements in these materials' toughness, and associated reliability in structural applications, uses will remain restricted to components in noncritical, nonman-rated aerospace applications such as cruise missile and drone gas turbine engine components. In such high temperature engine-section components, projected costs lie below those associated with superalloy-based short-life/expendable engines. Advancements are required in processing technology for the sake of fewer and smaller microstructural flaws.

  18. Ceramic composition

    International Nuclear Information System (INIS)

    Improved ceramic compositions useful for cutting tools and the like are described. They are composed of an essentially homogeneous admixture of sintered powders of an aluminum oxide base material with other refractories including zirconium oxide, titanium oxide, hafnium oxide, titanium nitride, zirconium nitride, and tungsten or molybdenum carbide. In addition to their common and improved properties of hardness and strength, many of these compositions may be made by simple cold-pressing and sintering procedures. This avoids the known drawbacks of conventional hot press production

  19. High-temperature testing of glass/ceramic matrix composites

    Science.gov (United States)

    Mandell, John F.; Grande, Dodd H.; Dannemann, Kathryn A.

    1989-01-01

    Recent advances in ceramic and other high-temperature composites have created a need for test methods that can be used at 1000 C and above. Present test methods usually require adhesively bonded tabs that cannot be used at high temperatures. This paper discusses some of the difficulties with high-temperature test development and describes several promising test methods. Stress-strain data are given for Nicalon ceramic fiber reinforced glass and glass-ceramic matrix composites tested in air at temperatures up to 1000 C.

  20. Fiber-reinforced composites in fixed partial dentures

    Directory of Open Access Journals (Sweden)

    Vallittu P

    2006-08-01

    Full Text Available Fiber-reinforced composite resin (FRC prostheses offer the advantages of good esthetics, minimal invasive treatment, and an ability to bond to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: fiber composites to build the framework and hybrid or microfill particulate composites to create the external veneer surface. This review concentrates on the use of fiber reinforcement in the fabrication of laboratory or chairside-made composite-fixed partial dentures of conventional preparation. Other applications of FRC in dentistry are briefly mentioned. The possibilities fiber reinforcement technology offers must be emphasized to the dental community. Rather than limiting discussion to whether FRC prostheses will replace metal-ceramic or full-ceramic prostheses, attention should be focused on the additional treatment options brought by the use of fibers. However, more clinical experience is needed.

  1. Effect of heat treatment on friction and wear behavior of al-6061 composite reinforced with 10% submicron Al2O3 particles

    International Nuclear Information System (INIS)

    The present research aims at investigating experimentally the effect of heat treatment on the hardness, wear behavior, and friction properties of 6061 Al composite reinforced with sub-micron Al2O3 (10% vol.) produced by powder metallurgy. Heat treatment of the as-received composite starts by the solution treatment at a temperature of 550 degree C for a period of two hours followed by quenching in chilled water and then age hardening at 175 degree C for different periods. It is illustrated that heat treatment has relatively small effect on the hardness of the composite. This can be attributed to the large interface areas between the matrix and the sub-micron alumina in the composite, which reduces the whole concentration of vacancies in the matrix. The result is reduced efficiency of age hardening. For this reason, wear and friction tests were limited to the heat treated composite with four hours aging only. A pin-on-disc tribometer was used to conduct wear and friction tests against AISI 4140 at room temperature for both as-received composite and heat treated composite (with four hours of aging) for comparison. Wear tests indicate that heat treatment has the advantage of increasing transition load to severe wear by 30% compared to as-received composite. On the other hand, at high loads heat treatment results in larger delaminated flakes on the worn surface, indicating reduced fracture toughness. This, in turn, resulted in higher wear rates compared to the as-received composite. Dry friction coefficient is practically unaffected by the heat treatment. (author)

  2. Porosity and mechanical properties of zirconium ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Buyakova, S., E-mail: sbuyakova@ispms.tsc.ru; Kulkov, S. [Tomsk State University (Russian Federation); Tomsk Polytechnic University (Russian Federation); Institute of Strength Physics and Materials Science RAS (Russian Federation); Sablina, T. [Institute of Strength Physics and Materials Science RAS (Russian Federation)

    2015-11-17

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO{sub 2}(MgO), ZrO{sub 2}(Y{sub 2}O{sub 3}) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO{sub 2} powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO{sub 2} grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  3. Porosity and mechanical properties of zirconium ceramics

    Science.gov (United States)

    Buyakova, S.; Sablina, T.; Kulkov, S.

    2015-11-01

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO2(MgO), ZrO2(Y2O3) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO2 powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO2 grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  4. Glasses, ceramics, and composites from lunar materials

    Science.gov (United States)

    Beall, George H.

    1992-02-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  5. Glasses, ceramics, and composites from lunar materials

    Science.gov (United States)

    Beall, George H.

    1992-01-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  6. Investigating aluminum alloy reinforced by graphene nanoflakes

    Energy Technology Data Exchange (ETDEWEB)

    Yan, S.J., E-mail: shaojiuyan@126.com [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Dai, S.L.; Zhang, X.Y.; Yang, C.; Hong, Q.H.; Chen, J.Z. [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Lin, Z.M. [Aviation Industry Corporation of China, Beijing 100022 (China)

    2014-08-26

    As one of the most important engineering materials, aluminum alloys have been widely applied in many fields. However, the requirement of enhancing their mechanical properties without sacrificing the ductility is always a challenge in the development of aluminum alloys. Thanks to the excellent physical and mechanical properties, graphene nanoflakes (GNFs) have been applied as promising reinforcing elements in various engineering materials, including polymers and ceramics. However, the investigation of GNFs as reinforcement phase in metals or alloys, especially in aluminum alloys, is still very limited. In this study, the aluminum alloy reinforced by GNFs was successfully prepared via powder metallurgy approach. The GNFs were mixed with aluminum alloy powders through ball milling and followed by hot isostatic pressing. The green body was then hot extruded to obtain the final GNFs reinforced aluminum alloy nanocomposite. The scanning electron microscopy and transmission electron microscope analysis show that GNFs were well dispersed in the aluminum alloy matrix and no chemical reactions were observed at the interfaces between the GNFs and aluminum alloy matrix. The mechanical properties' testing results show that with increasing filling content of GNFs, both tensile and yield strengths were remarkably increased without losing the ductility performance. These results not only provided a pathway to achieve the goal of preparing high strength aluminum alloys with excellent ductilitybut they also shed light on the development of other metal alloys reinforced by GNFs.

  7. Investigating aluminum alloy reinforced by graphene nanoflakes

    International Nuclear Information System (INIS)

    As one of the most important engineering materials, aluminum alloys have been widely applied in many fields. However, the requirement of enhancing their mechanical properties without sacrificing the ductility is always a challenge in the development of aluminum alloys. Thanks to the excellent physical and mechanical properties, graphene nanoflakes (GNFs) have been applied as promising reinforcing elements in various engineering materials, including polymers and ceramics. However, the investigation of GNFs as reinforcement phase in metals or alloys, especially in aluminum alloys, is still very limited. In this study, the aluminum alloy reinforced by GNFs was successfully prepared via powder metallurgy approach. The GNFs were mixed with aluminum alloy powders through ball milling and followed by hot isostatic pressing. The green body was then hot extruded to obtain the final GNFs reinforced aluminum alloy nanocomposite. The scanning electron microscopy and transmission electron microscope analysis show that GNFs were well dispersed in the aluminum alloy matrix and no chemical reactions were observed at the interfaces between the GNFs and aluminum alloy matrix. The mechanical properties' testing results show that with increasing filling content of GNFs, both tensile and yield strengths were remarkably increased without losing the ductility performance. These results not only provided a pathway to achieve the goal of preparing high strength aluminum alloys with excellent ductilitybut they also shed light on the development of other metal alloys reinforced by GNFs

  8. Fundamental alloy design of oxide ceramics and their composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, I.W.

    1992-01-01

    The main research was on microstructural development of oxide ceramics. Projects were completed and the publications given. Abstracts are given on: Reactive CeO[sub 2]powders by homogeneous precipitation, SiC whisker-reinforced lithium aluminosilicate composite, solute drag on grain boundary in ionic solids (space charge effect), in-situ alumina/aluminate platelet composites, exaggerated texture and grain growth of superplastic silicon nitride (SiAlON), hot extrusion of ceramics, control of grain boundary pinning in Al[sub 2]O[sub 3]/ZrO[sub 2] composites with Ce[sup 3+]/Ce[sup 4+] doping, superplastic forming of ceramic composites, computer simulation of final stage sintering (model, kinetics, microstructure, effect of initial pore size), development of superplastic structural ceramics, and superplastic flow of two-phase ceramics containing rigid inclusions (zirconia/mullite composites). A proposed research program is outlined: materials, solute drag, densification and coarsening, and grain boundary electrical behavior.

  9. Influence of nanosized carbon particles on the formation of the structure and properties of microarc ceramic coatings based on aluminum alloys

    International Nuclear Information System (INIS)

    A carbon-composite material based on a ceramic coating formed on aluminum alloys due to microarc oxidation and nanostructured carbon synthesized by the electric breakdown of liquid hydrocarbon (cyclohexane) is developed. The highest concentration of carbon nanoparticles is recorded in the coating surface coating 30-50 (μm in depth and also near the interface coating - base. It is shown that the nanocarbon introduced in electrolytes enhances the content of high-temperature modifications of aluminum oxide α-Al2O3 by a factor of 3, as compared to the coating resulting in a solution without additives. The latter achieves higher tribomechanical properties - the 1.6-fold increase of microhardness, the multiple growth of wear resistance in the high pressure range (45,60 MPa) with a simultaneous reduction of the coefficient 2-9 times. (authors)

  10. High Temperature Tolerant Ceramic Composites Having Porous Interphases

    Energy Technology Data Exchange (ETDEWEB)

    Kriven, Waltraud M. (Champaign, IL); Lee, Sang-Jin (Chonnam, KR)

    2005-05-03

    In general, this invention relates to a ceramic composite exhibiting enhanced toughness and decreased brittleness, and to a process of preparing the ceramic composite. The ceramic composite comprises a first matrix that includes a first ceramic material, preferably selected from the group including alumina (Al2O3), mullite (3Al2O3.2SiO2), yttrium aluminate garnet (YAG), yttria stabilized zirconia (YSZ), celsian (BaAl2Si2O8) and nickel aluminate (NiAl2O4). The ceramic composite also includes a porous interphase region that includes a substantially non-sinterable material. The non-sinterable material can be selected to include, for example, alumina platelets. The platelets lie in random 3-D orientation and provide a debonding mechanism, which is independent of temperature in chemically compatible matrices. The non-sinterable material induces constrained sintering of a ceramic powder resulting in permanent porosity in the interphase region. For high temperature properties, addition of a sinterable ceramic powder to the non-sinterable material provides sufficiently weak debonding interphases. The ceramic composite can be provided in a variety of forms including a laminate, a fibrous monolith, and a fiber-reinforced ceramic matrix. In the laminated systems, intimate mixing of strong versus tough microstructures were tailored by alternating various matrix-to-interphase thickness ratios to provide the bimodal laminate.

  11. Microstructural and sliding wear behavior of SiC-particle reinforced copper matrix composites fabricated by sintering and sinter-forging processes

    OpenAIRE

    Mohammadmehdi Shabani; Mohammad Hossein Paydar; Reza Zamiri; Maryam Goodarzi; Mohammad Mohsen Moshksar

    2016-01-01

    Cu and Cu/SiCp composite compacts were prepared through sintering and sinter-forging processes. Influence of SiC particles and fabrication type on the tribological behavior of pure Cu and Cu/SiCp composites was investigated. Dry sliding wear tests represented that the sinter-forged Cu composite compacts with 60 vol.% SiC exhibit the lowest wear loss compared to other compacts. Moreover, the results indicated that applying compressive force during sintering process of Cu and Cu/SiCp compacts h...

  12. Environmental durability of ceramics and ceramic composites

    Science.gov (United States)

    Fox, Dennis S.

    1992-01-01

    An account is given of the current understanding of the environmental durability of both monolithic ceramics and ceramic-matrix composites, with a view to the prospective development of methods for the characterization, prediction, and improvement of ceramics' environmental durability. Attention is given to the environmental degradation behaviors of SiC, Si3N4, Al2O3, and glass-ceramic matrix compositions. The focus of corrosion prevention in Si-based ceramics such as SiC and Si3N4 is on the high and low sulfur fuel combustion-product effects encountered in heat engine applications of these ceramics; sintering additives and raw material impurities are noted to play a decisive role in ceramics' high temperature environmental response.

  13. Dental ceramics: An update

    OpenAIRE

    Shenoy Arvind; Shenoy Nina

    2010-01-01

    In the last few decades, there have been tremendous advances in the mechanical properties and methods of fabrication of ceramic materials. While porcelain-based materials are still a major component of the market, there have been moves to replace metal ceramics systems with all ceramic systems. Advances in bonding techniques have increased the range and scope for use of ceramics in dentistry. In this brief review, we will discuss advances in ceramic materials and fabrication techniques. Examp...

  14. Tribo-Mechanical Properties of HVOF Deposited Fe3Al Coatings Reinforced with TiB2 Particles for Wear-Resistant Applications

    Directory of Open Access Journals (Sweden)

    Mahdi Amiriyan

    2016-02-01

    Full Text Available This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load.

  15. Fabrication of A356 composite reinforced with micro and nano Al{sub 2}O{sub 3} particles by a developed compocasting method and study of its properties

    Energy Technology Data Exchange (ETDEWEB)

    Sajjadi, S.A., E-mail: sajjadi@um.ac.ir [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Torabi Parizi, M. [Department of Materials Science and Engineering, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Ezatpour, H.R. [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Sedghi, A. [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Imam Khomeini International University of Qazvin, Qazvin (Iran, Islamic Republic of)

    2012-01-15

    Highlights: > In the current research micro and nano-composites of A356/Al{sub 2}O{sub 3} were produced by compocasting method in various conditions. > The effects of different fabrication parameters on the microstructure and some physical and mechanical properties of the composites have been investigated. > The results revealed that application of the compocasting process leads to a transformation of a dendritic to a nondendritic structure of the matrix alloy. - Abstract: Aluminum/alumina composites are used in automotive and aerospace industries due to their low density and good mechanical strength. In this study, compocasting was used to fabricate aluminum-matrix composite reinforced with micro and nano-alumina particles. Different weight fractions of micro (3, 5 and 7.5 wt.%) and nano (1, 2, 3 and 4 wt.%) alumina particles were injected by argon gas into the semi-solid state A356 aluminum alloy and stirred by a mechanical stirrer with different speeds of 200, 300 and 450 rpm. The microstructure of the composite samples was investigated by Optical and Scanning Electron Microscopy. Also, density and hardness variation of micro and nano composites were measured. The microstructure study results revealed that application of compocasting process led to a transformation of a dendritic to a nondendritic structure of the matrix alloy. The SEM micrographs revealed that Al{sub 2}O{sub 3} nano particles were surrounded by silicon eutectic and inclined to move toward inter-dendritic regions. They were dispersed uniformly in the matrix when 1, 2 and 3 wt.% nano Al{sub 2}O{sub 3} or 3 and 5 wt.% micro Al{sub 2}O{sub 3} was added, while, further increase in Al{sub 2}O{sub 3} (4 wt.% nano Al{sub 2}O{sub 3} and 7.5 wt.% micro Al{sub 2}O{sub 3}) led to agglomeration. The density measurements showed that the amount of porosity in the composites increased with increasing weight fraction and speed of stirring and decreasing particle size. The hardness results indicated that the

  16. Estructura y propiedades del material compuesto de base cobre reforzado con partículas intermetálicas de TiB2. // Structure and properties of copper base reinforced with intermetallic particles of TiB2 material.

    Directory of Open Access Journals (Sweden)

    M. López J.

    2002-09-01

    copper base reinforced alloy by means ofdispersion of TiB2 intermetalic ceramic is carried out. The copper-ceramic mechanical mixture was obtainedalloying powdered copper of 140 mm size with 1% and 2% of TiB2 in volume, dispers e in a planetary mill ofmartens itic stainless of high energy, with 12 and 36 hours milling in argon atmosphere using reason ofbolls/mass load in 10:1 powder. The powdered alloy consolidation was carried out in two stages.The objective of the study, is to investigate the evolution of mechanical and electric properties associated tomicroestructure changes taken place by compactacion process and hot lamination.Key words. Copper alloy, mechanical properties, microestructure, hot rolling.

  17. 粉末注射成形制备Si_3N_4颗粒增强316L不锈钢%Si_3N_4 particle-reinforced 316L stainless steel prepared by powder injection molding

    Institute of Scientific and Technical Information of China (English)

    田常娟; 何新波; 梅敏; 曲选辉

    2011-01-01

    Si3N4 particle-reinforced 316L stainless steel composites were prepared by powder injection molding(PIM) using water-soluble binders.It is shown that a water-soluble binder mainly consisting of polyoxymethylene(PEG),polyvinyl butyral(PVB) and stearic acid(SA) exhibits a better water-soluble degreasing performance.After degreasing injection parts in water for 6 h,the total binder removal rate is 55% and the PEG removal rate is 78.6%.The sintered composites have a uniform microstructure and excellent properties with a relative density of 95.2%,a hardness of HRB 79.8 and a tensile strength of 620 MPa.And the hardness and tensile strength are 5% and 20.4% higher than the Si3N4 particle-reinforced 316L stainless steel produced by PIM with a paraffin wax-based binder,respectively.%以多组元水溶性黏结剂为黏结剂,采用粉末注射成形工艺成功制备出了Si3N4颗粒增强316L不锈钢复合材料.研究表明:以聚乙二醇(PEG)、聚乙烯醇缩丁醛(PVB)和硬脂酸(SA)为主要成分的水溶性黏结剂表现出较好的水溶脱脂性能,注射坯在蒸馏水中脱脂6 h后,黏结剂总脱除率约为55%,其中PEG的脱除率约为78.6%;复合材料经烧结后组织均匀致密,性能良好,其致密度、硬度和拉伸强度分别为97.5%、HRB 81.7和620 MPa,其硬度和拉伸强度分别比采用石蜡基黏结剂制备的PIM--Si3N4增强316L不锈钢复合材料提高5%和20.4%.

  18. The synthesis and applications of nano sized ceramic membranes

    International Nuclear Information System (INIS)

    Inorganic membranes composed of particles having sizes below 50 A were produced with oxides of TiO2, ZrO2, and SiO2. This presentation stresses the necessary physical chemical phenomena associated with the particle synthesis and the aggregation behavior of these particles as they are incorporated into the final membrane body. Uses of ceramic membranes in separations, ceramic membrane reactors, and the photocatalytic degradation of organic waste materials are briefly reviewed

  19. Shear Reinforcements in the Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Moayyad M. Al-Nasra

    2013-10-01

    Full Text Available - This study focuses on the use of different types of shear reinforcement in the reinforced concrete beams. Four different types of shear reinforcement are investigated; traditional stirrups, welded swimmer bars, bolted swimmer bars, and u-link bolted swimmer bars. Beam shear strength as well as beam deflection are the main two factors considered in this study. Shear failure in reinforced concrete beams is one of the most undesirable modes of failure due to its rapid progression. This sudden type of failure made it necessary to explore more effective ways to design these beams for shear. The reinforced concrete beams show different behavior at the failure stage in shear compare to the bending, which is considered to be unsafe mode of failure. The diagonal cracks that develop due to excess shear forces are considerably wider than the flexural cracks. The cost and safety of shear reinforcement in reinforced concrete beams led to the study of other alternatives. Swimmer bar system is a new type of shear reinforcement. It is a small inclined bars, with its both ends bent horizontally for a short distance and welded or bolted to both top and bottom flexural steel reinforcement. Regardless of the number of swimmer bars used in each inclined plane, the swimmer bars form plane-crack interceptor system instead of bar-crack interceptor system when stirrups are used. Several reinforced concrete beams were carefully prepared and tested in the lab. The results of these tests will be presented and discussed. The deflection of each beam is also measured at incrementally increased applied load.

  20. Management of Reinforcement Corrosion

    DEFF Research Database (Denmark)

    Küter, André; Geiker, Mette Rica; Møller, Per

    Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management of...... reinforcement corrosion....

  1. Durabilidade de peças cerâmicas vermelhas com adição de rejeito de rocha ornamental isenta de granalha Durability of red ceramic samples with addition of ornamental rock waste free of steel particles

    Directory of Open Access Journals (Sweden)

    D. V. Rodrigues

    2012-09-01

    Full Text Available Para avaliação da degradação acelerada em laboratório sofrida pelos corpos de prova de cerâmica vermelha com adição de rejeito de rocha ornamental isento de granalha, foi utilizado um equipamento que lixivia com água quente e fria em tempos controlados, e também, congela a amostra em até -4 ºC. Os corpos de prova cerâmicos foram confeccionados com até 10% em massa de rejeito de rocha ornamental a seco, e em seguida, umedecidos e moldados por extrusão. Os materiais produzidos foram calcinados nas temperaturas de 700 ºC, 800 ºC e 900 ºC. Após 1060 h de degradação acelerada em equipamento de laboratório, analisaram-se as propriedades cerâmicas do material. Os resultados das resistências mecânicas foram comparados através da distribuição de Weibull, antes e depois da degradação. Nota-se que o material com adição de 10% de rejeito de rocha ornamental na massa cerâmica é mais confiável quando queimada a 900 ºC após a degradação, quando comparados com as amostras sem adição de rejeito, proporcionando maior durabilidade.For the evaluation of the accelerated degradation in laboratory of red ceramic specimens with addition of ornamental rock waste free from steel particles, an equipment that leach with hot and cool water and time control, and also freezing the specimen at -4 ºC was used,. The ceramic samples were made with up to 10 wt.% of the dry ornamental rock waste, and after humidifying and molding by extrusion. The specimens were fired at 700 ºC, 800 ºC and 900 ºC. After 1060 h of accelerated degradation lab test, ceramic properties were evaluated. The results of the strength were compared for Weibull distribution, before and after degradation. The specimens with addition of 10 wt.% waste is more durable and reliable when fired to 900 ºC after the degradation.

  2. Aluminium EN AC-AlSi12 alloy matrix composite materials reinforced by Al2O3 porous preforms

    OpenAIRE

    Nagel, A.; M. Kremzer; L.A. Dobrzański,

    2007-01-01

    Purpose: The purpose of this work is to elaborate the method of manufacturing of composite materials based on porous ceramic preforms infiltrated by eutectic aluminium alloy.Design/methodology/approach: The material for investigations was fabricated by pressure infiltration method of ceramic porous preforms. The eutectic aluminium alloy EN AC – AlSi12 was use as a matrix while as reinforcement were used ceramic preforms fabricated by sintering of Al2O3 Alcoa CL 2500 powder with addition of po...

  3. Preparation and Properties of Macroporous Silicon Nitride Ceramics by Gelcasting and Carbonthermal Reaction

    Institute of Scientific and Technical Information of China (English)

    Wen ZHANG; Hongjie WANG; Zhihao JIN

    2005-01-01

    Macroporous silicon nitride (Si3N4) ceramics with high strength, uniform structure and relatively high porosity were obtained by gelcasting and carbonthermal reaction in a two-step sintering technique. Microstructure and composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD). Open porosity, pore size distribution and basic mechanical performance were measured by Archimedes method,mercury intrusion porosimetry and three-point bending methods, respectively. SEM and TEM results revealed that pores were formed by elongated β-Si3N4. SADP measurement proved the formation of SiC particles. The SiC granules were beneficial for the formation of high ratio elongated β-Si3N4, and at proper amount, they also acted as reinforcement phase. Thermodynamic analysis indicated that the mechanisms of the reactions were mainly associated with liquid-solid reaction and gas-liquid reaction.

  4. Habituation of reinforcer effectiveness

    Directory of Open Access Journals (Sweden)

    David R Lloyd

    2014-01-01

    Full Text Available In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009;Rankin et al., 2009. We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect ‘accelerated-HRE’. Consideration of HRE is important for the development of effective reinforcement based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

  5. Dental ceramics: An update

    Directory of Open Access Journals (Sweden)

    Shenoy Arvind

    2010-01-01

    Full Text Available In the last few decades, there have been tremendous advances in the mechanical properties and methods of fabrication of ceramic materials. While porcelain-based materials are still a major component of the market, there have been moves to replace metal ceramics systems with all ceramic systems. Advances in bonding techniques have increased the range and scope for use of ceramics in dentistry. In this brief review, we will discuss advances in ceramic materials and fabrication techniques. Examples of the microstructure property relationships for these ceramic materials will also be addressed.

  6. Radiation Effects in Nuclear Ceramics

    Directory of Open Access Journals (Sweden)

    L. Thomé

    2012-01-01

    Full Text Available Due to outstanding physicochemical properties, ceramics are key engineering materials in many industrial domains. The evaluation of the damage created in ceramics employed in radiative media is a challenging problem for electronic, space, and nuclear industries. In this latter field, ceramics can be used as immobilization forms for radioactive wastes, inert fuel matrices for actinide transmutation, cladding materials for gas-cooled fission reactors, and structural components for fusion reactors. Information on the radiation stability of nuclear materials may be obtained by simulating the different types of interactions involved during the slowing down of energetic particles with ion beams delivered by various types of accelerators. This paper presents a review of the radiation effects occurring in nuclear ceramics, with an emphasis on recent results concerning the damage accumulation processes. Energetic ions in the KeV-GeV range are used to explore the nuclear collision (at low energy and electronic excitation (at high energy regimes. The recovery by electronic excitation of the damage created by ballistic collisions (SHIBIEC process is also addressed.

  7. Particle migration using local variation of the viscosity (LVOV) model in flow of a non-Newtonian fluid for ceramic tape casting

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Spangenberg, Jon; Hattel, Jesper Henri

    2016-01-01

    changes the particle distribution pattern from being a constant distribution to a semi-layered one. The presence of such layered structure is highly affecting the subsequent sintering process, which in turn causes anisotropic shrinkage of the dried tapes. Moreover, it is found that increasing the...

  8. Investigation of the chemical composition of (Na{sub 1-x}Bi {sub x})(Mn {sub y}Nb{sub 1-y})O{sub 3} ceramics by single particle electron probe X-ray microanalysis with an application of Monte Carlo simulations

    Energy Technology Data Exchange (ETDEWEB)

    Spolnik, Z. [Department of Chemistry, University of Antwerp, Campus ' Drie Eiken' , Universiteitsplein 1, B-2610 Antwerp (Belgium)]. E-mail: zoya.spolnik@ua.ac.be; Osan, J. [KFKI Atomic Energy Research Institute, P.O. Box 49, H-1525 Budapest (Hungary); Klepka, M. [Polish Academy of Science, Insitute of Physics, Al. Lotnikow 32/46 PL-02668, Warsaw (Poland); Lawniczak-Jablonska, K. [Polish Academy of Science, Insitute of Physics, Al. Lotnikow 32/46 PL-02668, Warsaw (Poland); Van Grieken, R. [Department of Chemistry, University of Antwerp, Campus ' Drie Eiken' , Universiteitsplein 1, B-2610 Antwerp (Belgium); Molak, A. [Institute of Physics, University of Silesia, ul. Uniwersytecka 4, PL-40-007 Katowice (Poland); Potgieter, J.H. [School of Process and Materials Engineering, University of the Witwatersrand, Private Bag X3, Wits, 2050 (South Africa)

    2005-04-30

    Accurate estimation of the elemental composition of materials that contain both low- and high-Z elements by electron probe X-ray microanalysis is not an easy task. An example of this kind of material is a new family of ceramics with general formula (Na{sub 1-x}Bi{sub x})(Mn {sub y}Nb{sub 1-y})O{sub 3}. To solve this problem, a method based on Monte Carlo simulations combined with an iterative approximation, which was recently successfully applied to quantitative analysis of the elemental content in aerosol particles, was used. The quantification procedure was evaluated on Bi{sub 2}O{sub 3}, PbO{sub 2} and NaNbO{sub 3} particles from stoichiometric compounds and applied to check the homogeneity and elemental contents of the selected ceramic after the application of different heat treatments.

  9. Numerical simulation on magnetic assembled structures of iron-based metallic particles within MMCs by a homogeneous strong magnetic field

    International Nuclear Information System (INIS)

    Particle-reinforced metal matrix composites (MMCs) have excellent physicochemical properties as structural materials. The morphology and distribution control of reinforcement particles during the fabrication of MMCs are difficult-but-critical-to-achieve required properties of the materials. This research demonstrates a possibility to quantitatively control the distribution of particles in the metal matrix by applying a magnetic field. A 2D numerical model is developed and applied to evaluate the behaviour of Fe-based metallic particles in aluminum MMCs. By combination of 2D simulation with intersectional directions, this model also provides some hints for 3D practice. The assembled structure is found to be governed by the external magnetic field orientation, magnetic flux density and magnetic susceptibility of the particles. Both behaviours of particle agglomeration and dispersion are quantitatively characterized in different conditions. By using a strong magnetic field, it is found that assembled structures of weakly magnetic particles can be effectively manipulated. Therefore, it can be expected to fabricate particle-enhanced metal matrix composites/ceramics/glass with substantial improvements in physical and chemical properties by using a magnetic field. (paper)

  10. Al-Ti Particulate Composite: Processing and Studies on Particle Twinning, Microstructure, and Thermal Stability

    Science.gov (United States)

    Yadav, Devinder; Bauri, Ranjit; Kauffmann, Alexander; Freudenberger, Jens

    2016-08-01

    The present investigation shows that alternate to the ceramic particles, hard metallic particles can be used as reinforcement in an aluminum matrix to achieve a good strength-ductility combination in a composite. Titanium particles were incorporated into aluminum by friction stir processing (FSP) to process an Al-Ti particulate composite. FSP led to uniform distribution of the particles in the stir zone without any particle-matrix reaction, thereby retaining the particles in their elemental state. Fracture and twinning of the Ti particles with different frequency of occurrence on the advancing and retreating sides of the stir zone was observed. Twinning of the particles was studied by focused ion beam-assisted transmission electron microscopy. The processed Al-Ti composite exhibited a significant improvement in strength and also retained appreciable amount of ductility. The thermal stability of the fine-grained structure against abnormal grain growth (AGG) was improved by the Ti particles. The AGG in the Al-Ti composite occurred at 713 K (440 °C) compared to 673 K (400 °C) in the unreinforced aluminum processed under the same conditions. On the other hand, the particle-matrix reaction occurred only at 823 K (550 °C), and hence the Ti particles were thermally more stable compared to the matrix grain structure.

  11. Fatigue of dental ceramics

    OpenAIRE

    Zhang, Yu; Sailer, Irena; lawn, brian

    2013-01-01

    Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics

  12. Effect of airborne particle abrasion protocols on surface topography of Y-TZP ceramic Efeito do protocolo de jateamento com partículas na topografia da superfície de uma cerâmica Y-TZP

    Directory of Open Access Journals (Sweden)

    J. R. C. Queiroz

    2012-06-01

    Full Text Available This study aimed to evaluate Y-TZP surface after different airborne particle abrasion protocols. Seventy-six Y-TZP ceramic blocks (5×4×4 mm³ were sintered and polished. Specimens were randomly divided into 19 groups (n=4 according to control group and 3 factors: a protocol duration (2 and 4 s; b particle size (30 µm, alumina coated silica particle; 45 µm, alumina particle; and 145 µm, alumina particle and; c pressure (1.5, 2.5 and 4.5 bar. Airborne particle abrasion was performed following a strict protocol. For qualitative and quantitative results, topography surfaces were analyzed in a digital optical profilometer (Interference Microscopic, using different roughness parameters (Ra, Rq, Rz, X-crossing, Mr1, Mr2 and Sdr and 3D images. Surface roughness also was analyzed following the primer and silane applications on Y-TZP surfaces. One-way ANOVA revealed that treatments (application period, particle size and pressure of particle blasting provided significant difference for all roughness parameters. The Tukey test determined that the significant differences between groups were different among roughness parameters. In qualitative analysis, the bonding agent application reduced roughness, filing the valleys in the surface. The protocols performed in this study verified that application period, particle size and pressure influenced the topographic pattern and amplitude of roughness.O objetivo deste estudo foi avaliar a superfície de uma cerâmica à base de zircônia tetragonal estabilizada por ítria (Y-TZP após diferentes protocolos de jateamento com partículas. Setenta e seis blocos cerâmicos de Y-TZP (5 x 4 x 4 mm³ foram sinterizados e polidos. As amostras foram randomicamente divididas em 19 grupos (n=4 sendo um controle e 18 grupos utilizando 3 fatores: a tempo (2 e 4 s; b tamanho de partícula (30 µm - partículas de alumina revestida por sílica; 45 µm - partículas de alumina; 145 µm - partículas de alumina e; c pressão (1

  13. Ceramic Laser Materials

    OpenAIRE

    Guillermo Villalobos; Jasbinder Sanghera; Ishwar Aggarwal; Bryan Sadowski; Jesse Frantz; Colin Baker; Brandon Shaw; Woohong Kim

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers,...

  14. Processing and properties of ceramic matrix-polymer composites for dental applications

    Science.gov (United States)

    Huang, Hsuan Yao

    The basic composite structure of natural hard tissue was used to guide the design and processing of dental restorative materials. The design incorporates the methodology of using inorganic minerals as the main structural phase reinforced with a more ductile but tougher organic phase. Ceramic-polymer composites were prepared by slip casting a porous ceramic structure, heating and chemical treating the porous preform, infiltrating with monomer and then curing. The three factors that determined the mechanical properties of alumina-polymer composites were the type of polymer used, the method of silane treatments, and the type of bond between particles in the porous preforms. Without the use of silane coupling agents, the composites were measured to have a lower strength. The composite with a more "flexible" porous alumina network had a greater ability to plastically dissipate the energy of propagating cracks. However, the aggressive nature of the alumina particles on opposing enamel requires that these alumina-polymer composites have a wear compatible coating for practical application. A route to dense bioactive apatite wollastonite glass ceramics (AWGC)-polymer composites was developed. The problems associated with glass dissolution into the aqueous medium for slip casting were overcome with the use of silane. The role of heating rate and development of ceramic compact microstructure on composite properties was explored. In general, if isothermal heating was not applied, decreasing heating rate increased glass crystallinity and particle-particle fusion, but decreased pore volume. Also composite strength and fracture toughness decreased while modulus and hardness increased with decreasing heating rate. If isothermal heating was applied, glass crystallinity, pore content, and composite mechanical properties showed relatively little change regardless of the initial heating rate. The potential of AWGC-polymer composites for dental and implant applications was explored

  15. Analysis of interface interaction and tensile properties of CaCO3 nano particle reinforced PVC composites%纳米CaCO3增韧聚氯乙烯复合材料的界面作用和拉伸性能探析

    Institute of Scientific and Technical Information of China (English)

    邓渊林

    2015-01-01

    with the development of the continued ascent speed in our country in the field of composite materials and composite gradually,has been more and more research of nano CaCO3 particle reinforced PVC composites.This paper expounded through the interface function of CaCO3 nano particle reinforced PVC composites,tensile properties of nano CaCO3 particle reinforced PVC composites are analyzed.%随着我国复合材料领域发展速度的持续提升和复合材料研究的逐渐深入,纳米CaCO3增韧聚氯乙烯复合材料得到了越来越多的研究。本文通过对纳米CaCO3增韧聚氯乙烯复合材料的界面作用进行阐述,对纳米CaCO3增韧聚氯乙烯复合材料的拉伸性能进行了分析。

  16. Choice and multiple reinforcers

    OpenAIRE

    Moore, Jay

    1982-01-01

    Pigeons chose between equivalent two-component mixed and multiple terminal-link schedules of reinforcement in the concurrent-chains procedure. The pigeons preferred the multiple schedule over the mixed when the components of the compound schedules were differentiated in terms of density of reinforcement, but the pigeons were indifferent when the components were differentiated in terms of number of reinforcers per cycle. Taken together, these results indicate that a local variable, the interva...

  17. Centrifugal Infiltration of Porous Ceramic Preforms by the Liquid Al Alloy – Theoretical Background and Experimental Verification

    OpenAIRE

    Dolata A.J.

    2016-01-01

    The goal of this work is the description of phenomena occurring during centrifugal infiltration of porous ceramic materials by liquid Al alloy. In this method, the pressure required to infiltration of liquid metal into pores of ceramic is generated by centrifugal force. From the beginning it was assumed that the porous ceramic material will create reinforcement layer in specific area of the casting. The forces that influence on the liquid metal during mould centrifugation and heat exchange be...

  18. Influence of in situ formed ZrB2 particles on microstructure and mechanical properties of AA6061 metal matrix composites

    International Nuclear Information System (INIS)

    Highlights: → In situ fabrication of aluminium metal matrix composite reinforced ZrB2 particles. → Colour metallography of composites. → Improvement of matrix properties by ZrB2 particles. → Sliding wear behaviour of in situ composites. - Abstract: Particulate reinforced metal matrix composites (PMMCs) have gained considerable amount of research emphasis and attention in the present era. Research is being carried out across the globe to produce new combination of PMMCs. PMMCs are prepared by adding a variety of ceramic particles with monolithic alloys using several techniques. An attempt has been made to produce aluminium metal matrix composites reinforced with zirconium boride (ZrB2) particles by the in situ reaction of K2ZrF6 and KBF4 salts with molten aluminium. The influence of in situ formed ZrB2 particles on the microstructure and mechanical properties of AA6061 alloy was studied in this work. The in situ formed ZrB2 particles significantly refined the microstructure and enhanced the mechanical properties of AA6061 alloy. The weight percentage of ZrB2 was varied from 0 to 10 in steps of 2.5. Improvement of hardness, ultimate tensile strength and wear resistance of AA6061 alloy was observed with the increase in ZrB2 content.

  19. Mechanical properties of microwave sintered Si3N4-based ceramics

    Directory of Open Access Journals (Sweden)

    Getman O.I.

    2002-01-01

    Full Text Available The mechanical properties and microstructure formation processes in Si3N4+3% AI2O3+5% Y2O3(Yb2O3 ceramic compacts sintered under microwave heating (MWH and under traditional heating (TH were investigated. The initial ceramic materials were powder blends of silicon nitride with oxides. The mean powder particle sizes were 0.5-1.0 mim. The content of alfa-phase in the Si3N4 powder was more than 95 %. The samples were sintered at 1800BC in nitrogen at normal pressure, the heating rate in all experiments was 60BC/min. The Vickers hardness (HV, fracture toughness (K1C and bending strength (on were determined. The microstructures of fracture surfaces of samples were studied by SEM. Quantitative microstructure analysis was carried out. It was shown that the values of HV and Kic of ceramic samples sintered under MWH at 1800BC rose steadily with the sintering time. This caused an increase in density, which reached maximum as fast as after 30 min of the MWH sintering; the mass loss at that time amounted to 3-4 %. The porosity of sintered samples with an addition of yttria was less than 1 %, that of ytterbia was greater, 2.4 %. For similar values of relative density, the hardness and fracture toughness of ceramic samples produced under MWH were higher as compared with those of samples sintered under TH. The microstructure of samples had the form of elongated grains in a matrix of polyhedral grains of the beta-Si3N4 phase. Measurements showed the mean size of grains in samples produced by MWH to be greater that in samples produced by TH. A larger number of elongated grains were formed. It was concluded that for sintering under MWH of Si3N4-based ceramics the growth of elongated beta-Si3N4 grains and formation of a "reinforced" microstructure were promoted and thereby improved the mechanical properties of such ceramics.

  20. Thermal oxidation of medical Ti6Al4V blasted with ceramic particles: Effects on the microstructure, residual stresses and mechanical properties.

    Science.gov (United States)

    Lieblich, M; Barriuso, S; Multigner, M; González-Doncel, G; González-Carrasco, J L

    2016-02-01

    Roughening of Ti6Al4V by blasting with alumina or zirconia particles improves the mechanical fixation of implants by increasing the surface area available for bone/implant apposition. Additional thermal oxidation treatments of the blasted alloy have already shown to be a complementary low-cost solution to enhancing the in vitro biocompatibility and corrosion resistance of the alloy. In this work, the effects of oxidation treatment on a grit blasted Ti6Al4V biomedical alloy have been analysed in order to understand the net effect of the combined treatments on the alloy fatigue properties. Synchrotron radiation diffraction experiments have been performed to measure residual stresses before and after the treatments and microstructural and hardness changes have been determined. Although blasting of Ti6Al4V with small spherical zirconia particles increases the alloy fatigue resistance with respect to unblasted specimens, fatigue strength after oxidation decreases below the unblasted value, irrespective of the type of particle used for blasting. Moreover, at 700°C the as-blasted compressive residual stresses (700MPa) are not only fully relaxed but even moderate tensile residual stresses, of about 120MPa, are found beneath the blasted surfaces. Contrary to expectations, a moderate increase in hardness occurs towards the blasted surface after oxidation treatments. This can be attributed to the fact that grit blasting modifies the crystallographic texture of the Ti6Al4V shifting it to a random texture, which affects the hardness values as shown by additional experiments on cold rolled samples. The results indicate that the oxidation treatment performed to improve biocompatibility and corrosion resistance of grit blasted Ti6Al4V should be carried out with caution since the alloy fatigue strength can be critically diminished below the value required for high load-bearing components. PMID:26458115