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Sample records for fast sinter thick

  1. Excimer laser sintering of indium tin oxide nanoparticles for fabricating thin films of variable thickness on flexible substrates

    International Nuclear Information System (INIS)

    Park, Taesoon; Kim, Dongsik

    2015-01-01

    Technology to fabricate electrically-conducting, transparent thin-film patterns on flexible substrates has possible applications in flexible electronics. In this work, a pulsed-laser sintering process applicable to indium tin oxide (ITO) thin-film fabrication on a substrate without thermal damage to the substrate was developed. A nanosecond pulsed laser was used to minimize thermal penetration into the substrate and to control the thickness of the sintered layer. ITO nanoparticles (NPs) of ~ 20 nm diameter were used to lower the process temperature by exploiting their low melting point. ITO thin film patterns were fabricated by first spin coating the NPs onto a surface, then sintering them using a KrF excimer laser. The sintered films were characterized using field emission scanning electron microscopy. The electrical resistivity and transparency of the film were measured by varying the process parameters. A single laser pulse could generate the polycrystalline structure (average grain size ~ 200 nm), reducing the electrical resistivity of the film by a factor of ~ 1000. The sintering process led to a minimum resistivity of 1.1 × 10 −4 Ω·m without losing the transparency of the film. The thickness of the sintered layer could be varied up to 150 nm by adjusting the laser fluence. Because the estimated thermal penetration depth in the ITO film was less than 200 nm, no thermal damage was observed in the substrate. This work suggests that the proposed process, combined with various particle deposition methods, can be an effective tool to form thin-film ITO patterns on flexible substrates. - Highlights: • Excimer laser sintering can fabricate ITO thin films on flexible substrates. • The laser pulse can form a polycrystalline structure without thermal damage. • The laser sintering process can reduce the electrical resistivity substantially. • The thickness of the sintered layer can be varied effectively

  2. Excimer laser sintering of indium tin oxide nanoparticles for fabricating thin films of variable thickness on flexible substrates

    Energy Technology Data Exchange (ETDEWEB)

    Park, Taesoon; Kim, Dongsik, E-mail: dskim87@postech.ac.kr

    2015-03-02

    Technology to fabricate electrically-conducting, transparent thin-film patterns on flexible substrates has possible applications in flexible electronics. In this work, a pulsed-laser sintering process applicable to indium tin oxide (ITO) thin-film fabrication on a substrate without thermal damage to the substrate was developed. A nanosecond pulsed laser was used to minimize thermal penetration into the substrate and to control the thickness of the sintered layer. ITO nanoparticles (NPs) of ~ 20 nm diameter were used to lower the process temperature by exploiting their low melting point. ITO thin film patterns were fabricated by first spin coating the NPs onto a surface, then sintering them using a KrF excimer laser. The sintered films were characterized using field emission scanning electron microscopy. The electrical resistivity and transparency of the film were measured by varying the process parameters. A single laser pulse could generate the polycrystalline structure (average grain size ~ 200 nm), reducing the electrical resistivity of the film by a factor of ~ 1000. The sintering process led to a minimum resistivity of 1.1 × 10{sup −4} Ω·m without losing the transparency of the film. The thickness of the sintered layer could be varied up to 150 nm by adjusting the laser fluence. Because the estimated thermal penetration depth in the ITO film was less than 200 nm, no thermal damage was observed in the substrate. This work suggests that the proposed process, combined with various particle deposition methods, can be an effective tool to form thin-film ITO patterns on flexible substrates. - Highlights: • Excimer laser sintering can fabricate ITO thin films on flexible substrates. • The laser pulse can form a polycrystalline structure without thermal damage. • The laser sintering process can reduce the electrical resistivity substantially. • The thickness of the sintered layer can be varied effectively.

  3. Sintering behavior of porous wall tile bodies during fast single-firing process

    Directory of Open Access Journals (Sweden)

    Sidnei José Gomes Sousa

    2005-06-01

    Full Text Available In ceramic wall tile processing, fast single-firing cycles have been widely used. In this investigation a fast single-firing porous wall tile mixture was prepared using raw materials from the North Fluminense region.Specimens were obtained by uniaxial pressing and sintered in air at various temperatures (1080 - 1200 °C using a fast-firing cycle (60 minutes. Evolution of the microstructure was followed by XRD and SEM. The results revealed that the main phases formed during the sintering step are anorthite, gehlenite and hematite. It appears that the sintering process is characterized by the presence of a small amount of a liquid phase below 1140 °C. As a result, the microstructure of the ceramic bodies showed a network of small dense zones interconnected with a porous phase. In addition, the strength of the material below 1140 °C appeared to be related to the type and quantity of crystalline phases in the sintered bodies.

  4. Fast femtosecond laser ablation for efficient cutting of sintered alumina substrates

    Science.gov (United States)

    Oosterbeek, Reece N.; Ward, Thomas; Ashforth, Simon; Bodley, Owen; Rodda, Andrew E.; Simpson, M. Cather

    2016-09-01

    Fast, accurate cutting of technical ceramics is a significant technological challenge because of these materials' typical high mechanical strength and thermal resistance. Femtosecond pulsed lasers offer significant promise for meeting this challenge. Femtosecond pulses can machine nearly any material with small kerf and little to no collateral damage to the surrounding material. The main drawback to femtosecond laser machining of ceramics is slow processing speed. In this work we report on the improvement of femtosecond laser cutting of sintered alumina substrates through optimisation of laser processing parameters. The femtosecond laser ablation thresholds for sintered alumina were measured using the diagonal scan method. Incubation effects were found to fit a defect accumulation model, with Fth,1=6.0 J/cm2 (±0.3) and Fth,∞=2.5 J/cm2 (±0.2). The focal length and depth, laser power, number of passes, and material translation speed were optimised for ablation speed and high quality. Optimal conditions of 500 mW power, 100 mm focal length, 2000 μm/s material translation speed, with 14 passes, produced complete cutting of the alumina substrate at an overall processing speed of 143 μm/s - more than 4 times faster than the maximum reported overall processing speed previously achieved by Wang et al. [1]. This process significantly increases processing speeds of alumina substrates, thereby reducing costs, making femtosecond laser machining a more viable option for industrial users.

  5. Effect of Reduced Meal Frequency during Ramadan Fasting on Retinal and Choroidal Thickness.

    Science.gov (United States)

    Ersan, Ismail; Tufan, Hasan Ali; Arikan, Sedat; Kara, Selcuk; Gencer, Baran; Hondur, Ahmet Murat

    2017-01-01

    To evaluate the effects of Ramadan fasting on central foveal thickness (CFT) and subfoveal choroidal thickness (SFCT) in healthy individuals using enhanced depth imaging optical coherence tomography (EDI-OCT). The EDI-OCT scans of 42 healthy individuals obtained after about 12 hours of fasting on at least the twenty-first consecutive day of fasting were compared to scans of the same patients taken one month after the last day they had fasted. CFT values were similar for both time periods (p > 0.05). The SFCT was significantly higher after consecutive fasting days towards the end of Ramadan, compared to the SFCT after one month of no fasting (one month after Ramadan ended) (p Ramadan fasting may lead to a significant increase in subfoveal choroidal thickness without affecting the central foveal thickness.

  6. Fast plasma sintering delivers functional graded materials components with macroporous structures and osseointegration properties.

    Science.gov (United States)

    Godoy, R F; Coathup, M J; Blunn, G W; Alves, A L; Robotti, P; Goodship, A E

    2016-04-13

    We explored the osseointegration potential of two macroporous titanium surfaces obtained using fast plasma sintering (FPS): Ti macroporous structures with 400-600 µmØ pores (TiMac400) and 850-1000 µmØ pores (TiMac850). They were compared against two surfaces currently in clinical use: Ti-Growth® and air plasma spray (Ti-Y367). Each surface was tested, once placed over a Ti-alloy and once onto a CoCr bulk substrate. Implants were placed in medial femoral condyles in 24 sheep. Samples were explanted at four and eight weeks after surgery. Push-out loads were measured using a material-testing system. Bone contact and ingrowth were assessed by histomorphometry and SEM and EDX analyses. Histology showed early osseointegration for all the surfaces tested. At 8 weeks, TiMac400, TiMac850 and Ti-Growth® showed deep bone ingrowth and extended colonisation with newly formed bone. The mechanical push-out force was equal in all tested surfaces. Plasma spray surfaces showed greater bone-implant contact and higher level of pores colonisation with new bone than FPS produced surfaces. However, the void pore area in FPS specimens was significantly higher, yet the FPS porous surfaces allowed a deeper osseointegration of bone to implant. FPS manufactured specimens showed similar osseointegration potential to the plasma spray surfaces for orthopaedic implants. FPS is a useful technology for manufacturing macroporous titanium surfaces. Furthermore, its capability to combine two implantable materials, using bulk CoCr with macroporous titanium surfaces, could be of interest as it enables designers to conceive and manufacture innovative components. FPS delivers functional graded materials components with macroporous structures optimised for osseointegration.

  7. [Effect of repeated sintering and variations in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers].

    Science.gov (United States)

    Cui, Huang; Jia, Yu; Shaofeng, Meng; Biyun, Gao

    2017-08-01

    Objective The aim of this study is to evaluate the effect of repeated sintering and variation in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers. Methods A total of 24 computer aided design and computer aided manufacturing (CAD/CAM) veneers was fabricated using the IPS e.max-CAD LS2 and then randomly divided into four groups (S0, S1, S2, S3; n=6). Each group was sintered 0, 1, 2, 3 times individually according to the manufacturer's recommendation. The color parameters (L, C, H, a, b values) of all the specimens were measured by a Vita easyshade dental colorimeter. The results were statistically analyzed using the SAS 9.1.3 software for MANOVA and LSD. Subsequently, the microstructures of the intersecting surfaces of the specimens were observed by scanning electron microscopy (SEM). Results After repeated sintering, the L value significantly decreased (P<0.05). For the C and b values, statistical differences were observed among the groups except between S2 and S3. SEM results showed that the interlocking microstructures of rod-shaped Li₂Si₂O₅ crystals became more compact when the number of sintering times was increased. Conclusion Repeated sintering exhibited significant influence on the color of the IPS e.max-CAD LS2 veneers.

  8. Room and ultrahigh temperature structure-mechanical property relationships of tungsten alloys formed by field assisted sintering technique (FAST)

    Energy Technology Data Exchange (ETDEWEB)

    Browning, Paul N.; Alagic, Sven [Pennsylvania State University, Department of Materials Science and Engineering, State College, PA-16801 (United States); Pennsylvania State University, Applied Research Laboratory, State College, PA-16801 (United States); Kulkarni, Anil [Pennsylvania State University, Department of Nuclear and Mechanical Engineering, State College, PA-16801 (United States); Matson, Lawrence [Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Dayton, OH (United States); Singh, Jogender, E-mail: jxs46@arl.psu.edu [Pennsylvania State University, Department of Materials Science and Engineering, State College, PA-16801 (United States); Pennsylvania State University, Applied Research Laboratory, State College, PA-16801 (United States)

    2016-09-30

    Tungsten based alloys have become of critical importance in a number of applications including plasma-facing materials in nuclear fusion reactors, rocket nozzles for aerospace applications, and in kinetic energy penetrators in the defense industry. Formation of components for these uses by powder metallurgical techniques has proven challenging, due to tungsten's relatively poor sinterability. Here we report the use of field assisted sintering technique (FAST) to produce high density, fine grain alloys with mechanical properties comparable or superior to that of components produced by conventional techniques. Alloys of pure tungsten, W-3 vol%TiC, W-5 vol%TiC, and W-10 vol%Ta were synthesized at 2100 °C, 35 MPa for 25 min using FAST. Microstructural characterization revealed effective reduction of grain size with TiC addition and preferential diffusion of oxygen into the center of tantalum particles in tantalum containing alloys. Tensile testing of alloys revealed TiC addition to W resulted in substantially improved ultimate tensile strength at the cost of ductility in comparison at temperatures up to 1926 °C (3500 °F) however this strengthening effect was lost at 2204 °C (4000 °F). Addition of 10 vol%Ta to W resulted in reduced hardness at room temperature, but substantially increased yield strength at the cost of slightly reduced ductility at 1926 °C and 2204 °C.

  9. Luminescence Characteristics of ZnGa2O4 Thick Film Doped with Mn2+ and Cr3+ at Various Sintering Temperatures

    Science.gov (United States)

    Cha, Jae Hyeok; Kim, Kyung Hwan; Park, Yong Seo; Kwon, Sang Jik; Choi, Hyung Wook

    2007-10-01

    ZnGa2O4 phosphor separately doped with Mn2+ and Cr3+ was synthesized by solid-state reaction, and thick films were deposited by screen printing. The X-ray diffraction (XRD) patterns of ZnGa2O4 phosphor thick films show a (311) main peak and a spinal phase. Uniform distribution and filled morphology of the doped ZnGa2O4 phosphor thick films were formed at the sintering temperature of 1100 °C. The CL spectrum of Mn2+-doped ZnGa2O4 shows the main peak of 512 nm green emission with the 4T1→6A1 transition of Mn2+ ions and the CL spectrum of Cr3+-doped ZnGa2O4 shows the main peak of 716 nm red emission with the 2E→4A2 transition of Cr3+ ions.

  10. Electromagnetic characterization of microwave sintered Sr1-xCaxMnO3 (0.0 ≤ x ≤ 0.4 thick films

    Directory of Open Access Journals (Sweden)

    Rani P. Pawar

    2013-03-01

    Full Text Available Electromagnetic characteristics of microwave sintered strontium calcium manganites thick film with variation in calcium content have been investigated. The X-ray diffraction analysis reveals tetragonal perovskite structure for all the compositions. The grain size increases with the increase in calcium content. The microwave absorption, complex permittivity, permeability and conductivity are reported in the frequency range of 8.2–18 GHz. The absorption loss is larger in Ku band while insertion loss is larger in X band. The permittivity, permeability and microwave conductivity decreases from X-band to Ku-band. The almost identical values of real part of permittivity and permeability indicate possible application as materials for impedance matching.

  11. A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes.

    Science.gov (United States)

    Rubino, Stefano; Akhtar, Sultan; Leifer, Klaus

    2016-02-01

    We present a simple, fast method for thickness characterization of suspended graphene/graphite flakes that is based on transmission electron microscopy (TEM). We derive an analytical expression for the intensity of the transmitted electron beam I 0(t), as a function of the specimen thickness t (tgraphite). We show that in thin graphite crystals the transmitted intensity is a linear function of t. Furthermore, high-resolution (HR) TEM simulations are performed to obtain λ for a 001 zone axis orientation, in a two-beam case and in a low symmetry orientation. Subsequently, HR (used to determine t) and bright-field (to measure I 0(0) and I 0(t)) images were acquired to experimentally determine λ. The experimental value measured in low symmetry orientation matches the calculated value (i.e., λ=225±9 nm). The simulations also show that the linear approximation is valid up to a sample thickness of 3-4 nm regardless of the orientation and up to several ten nanometers for a low symmetry orientation. When compared with standard techniques for thickness determination of graphene/graphite, the method we propose has the advantage of being simple and fast, requiring only the acquisition of bright-field images.

  12. Fast neutron responses of CaF2:Tm Teflon TLD discs of different thicknesses

    International Nuclear Information System (INIS)

    Pradhan, A.S.; Hoffmann, W.

    1986-01-01

    The fact that in CaF 2 :Tm (TLD-300) the ratio of the heights of thermoluminescence (TL) glow peaks at 240 0 C and 150 0 C is greater for irradiations by high LET radiations than by gamma rays has been found useful for the simultaneous and separate measurement of fast neutron and gamma ray absorbed doses. A recent study has indicated that the mixed field dosimetric characteristics of CaF 2 :Tm could be significantly improved by using thin TLDs. In the present study, CaF 2 :Tm Teflon TLD discs of thickness as low as 0.05 mm were evaluated. The thin discs could be read out by using normal planchette heating if a 400 0 C heat treatment is given to the discs prior to irradiation and TL readout. Influence of encapsulation of thin dosemeters was studied and their utility in situations such as interface dosimetry is discussed. (author)

  13. Consistency of ocular coherence tomography fast macular thickness mapping in diabetic diffuse macular edema

    International Nuclear Information System (INIS)

    Saraiva, Fabio Petersen; Costa, Patricia Grativol; Inomata, Daniela Lumi; Melo, Carlos Sergio Nascimento; Helal Junior, John; Nakashima, Yoshitaka

    2007-01-01

    Objectives: To investigate optical coherence tomography consistency on foveal thickness, foveal volume, and macular volume measurements in patients with and without diffuse diabetic macular edema. Introduction: Optical coherence tomography represents an objective technique that provides cross-sectional tomographs of retinal structure in vivo. However, it is expected that poor fixation ability, as seen in diabetic macular edema, could alter its results. Several authors have discussed the reproducibility of optical coherence tomography, but only a few have addressed the topic with respect to diabetic maculopathy. Methods: The study recruited diabetic patients without clinically evident retinopathy (control group) and with diffuse macular edema (case group). Only one eye of each patient was evaluated. Five consecutive fast macular scans were taken using Ocular Coherence Tomography 3; the 6 mm macular map was chosen. The consistency in measurements of foveal thickness, foveal volume, and total macular volume for both groups was evaluated using the Pearson's coefficient of variation. The T-test for independent samples was used in order to compare measurements of both groups. Results: Each group consisted of 20 patients. All measurements had a coefficient of variation less than 10%. The most consistent parameter for both groups was the total macular volume. Discussion: Consistency in measurement is a mainstay of any test. A test is unreliable if its measurements can not be correctly repeated. We found a good index of consistency, even considering patients with an unstable gaze. Conclusions: Optical coherence tomography is a consistent method for diabetic subjects with diffuse macular edema. (author)

  14. Consistency of ocular coherence tomography fast macular thickness mapping in diabetic diffuse macular edema

    Energy Technology Data Exchange (ETDEWEB)

    Saraiva, Fabio Petersen; Costa, Patricia Grativol; Inomata, Daniela Lumi; Melo, Carlos Sergio Nascimento; Helal Junior, John; Nakashima, Yoshitaka [Universidade de Sao Paulo (USP), SP (Brazil). Hospital das Clinicas. Dept. de Oftalmologia]. E-mail: fabiopetersen@yahoo.com.br

    2007-07-01

    Objectives: To investigate optical coherence tomography consistency on foveal thickness, foveal volume, and macular volume measurements in patients with and without diffuse diabetic macular edema. Introduction: Optical coherence tomography represents an objective technique that provides cross-sectional tomographs of retinal structure in vivo. However, it is expected that poor fixation ability, as seen in diabetic macular edema, could alter its results. Several authors have discussed the reproducibility of optical coherence tomography, but only a few have addressed the topic with respect to diabetic maculopathy. Methods: The study recruited diabetic patients without clinically evident retinopathy (control group) and with diffuse macular edema (case group). Only one eye of each patient was evaluated. Five consecutive fast macular scans were taken using Ocular Coherence Tomography 3; the 6 mm macular map was chosen. The consistency in measurements of foveal thickness, foveal volume, and total macular volume for both groups was evaluated using the Pearson's coefficient of variation. The T-test for independent samples was used in order to compare measurements of both groups. Results: Each group consisted of 20 patients. All measurements had a coefficient of variation less than 10%. The most consistent parameter for both groups was the total macular volume. Discussion: Consistency in measurement is a mainstay of any test. A test is unreliable if its measurements can not be correctly repeated. We found a good index of consistency, even considering patients with an unstable gaze. Conclusions: Optical coherence tomography is a consistent method for diabetic subjects with diffuse macular edema. (author)

  15. Ultra-fast microwave sintering of PZT/FCO particulate composites prepared by ultrasonic mixing; Sinterizacao ultrarrapida por micro-ondas de compositos particulados PZT/FCO preparados por mistura em ultrassom

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, C.P.; Zabotto, F.L.; Garcia, D.; Kiminami, R.H.G.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2017-07-15

    Pb(Zr{sub 0.53}Ti{sub 0.47})O{sub 3} (PZT) and Fe{sub 2}CoO{sub 4} (FCO) powders were synthesized separately by the Pechini method and then ultrasonically mixed in molar proportions of 80/20 and 50/50 of PZT/FCO. The resulting composites were pressed and subjected to conventional and ultrafast microwave-assisted sintering. The structure and microstructure of the sintered samples were analyzed, respectively, by X-ray diffraction and scanning electron microscopy. The dielectric constant as a function of temperature, electrical resistivity and magnetoelectric coupling coefficient were measured. The results indicated that the ultrasonic mixing method applied to PZT and FCO was fast and efficient, and that sintering resulted in globally connected (0-3) particulate composites and uniform distribution of the ferromagnetic phase (FCO) grains in the ferroelectric matrix (PZT). The structural analysis indicated that microwave sintering changed the arrangement (1-3) of the material's local connectivity, which was attributed to the intensification of diffusion processes that occur in this type of sintering, particularly in nanometric systems. The high values of resistivity indicated that although both sintering methods preserved the integrity of the two phases, microwave sintering was more efficient, ensuring the magnetoelectric behavior of all the composites under study. The values of H{sub max} field were dependent on the ferrite phase concentration and sintering; 80/20 1.4 and 1.9 kOe, and 50/50 3.5 and 3.0 kOe in the samples sintered by microwave and conventionally, consistent with the literature, which confirmed the integrity of the constituent phases PZT and FCO. (author)

  16. Field assisted sintering of refractory carbide ceramics and fiber reinforced ceramic matrix composites

    Science.gov (United States)

    Gephart, Sean

    The sintering behaviors of silicon carbide (SiC) and boron carbide (B4C) based materials were investigated using an emerging sintering technology known as field assisted sintering technology (FAST), also known as spark plasma sintering (SPS) and pulse electric current sintering (PECS). Sintering by FAST utilizes high density electric current, uniaxial pressure, and relatively high heating rate compared to conventional sintering techniques. This effort investigated issues of scaling from laboratory FAST system (25 ton capacity) to industrial FAST system (250 ton capacity), as well as exploring the difference in sintering behavior of single phase B4C and SiC using FAST and conventional sintering techniques including hot-pressing (HP) and pressure-less sintering (PL). Materials were analyzed for mechanical and bulk properties, including characterization of density, hardness, fracture toughness, fracture (bend) strength, elastic modulus and microstructure. A parallel investigation was conducted in the development of ceramic matrix composites (CMC) using SiC powder impregnation of fiber compacts followed by FAST sintering. The FAST technique was used to sinter several B4C and SiC materials to near theoretical density. Preliminary efforts established optimized sintering temperatures using the smaller 25 ton laboratory unit, targeting a sample size of 40 mm diameter and 8 mm thickness. Then the same B4C and SiC materials were sintered by the larger 250 ton industrial FAST system, a HP system, and PL sintering system with a targeted dense material geometry of 4 x 4 x 0.315 inches3 (101.6 x 101.6 x 8 mm3). The resulting samples were studied to determine if the sintering dynamics and/or the resulting material properties were influenced by the sintering technique employed. This study determined that FAST sintered ceramic materials resulted in consistently higher averaged values for mechanical properties as well as smaller grain size when compared to conventionally sintered

  17. Thick film hydrogen sensor

    Science.gov (United States)

    Hoffheins, Barbara S.; Lauf, Robert J.

    1995-01-01

    A thick film hydrogen sensor element includes an essentially inert, electrically-insulating substrate having deposited thereon a thick film metallization forming at least two resistors. The metallization is a sintered composition of Pd and a sinterable binder such as glass frit. An essentially inert, electrically insulating, hydrogen impermeable passivation layer covers at least one of the resistors.

  18. Laser sintering of copper nanoparticles

    International Nuclear Information System (INIS)

    Zenou, Michael; Saar, Amir; Ermak, Oleg; Kotler, Zvi

    2014-01-01

    Copper nanoparticle (NP) inks serve as an attractive potential replacement to silver NP inks in functional printing applications. However their tendency to rapidly oxidize has so far limited their wider use. In this work we have studied the conditions for laser sintering of Cu-NP inks in ambient conditions while avoiding oxidation. We have determined the regime for stable, low-resistivity copper (< ×3 bulk resistivity value) generation in terms of laser irradiance and exposure duration and have indicated the limits on fast processing. The role of pre-drying conditions on sintering outcome has also been studied. A method, based on spectral reflectivity measurements, was used for non-contact monitoring of the sintering process evolution. It also indicates preferred spectral regions for sintering. Finally, we illustrated how selective laser sintering can generate high-quality, fine line (<5 µm wide) and dense copper circuits. (paper)

  19. Fast neutron forward distributions from C, Be and U thick targets bombarded by deuterons

    International Nuclear Information System (INIS)

    Menard, S.; Clapier, F.; Pauwels, N.; Proust, J.; Donzaud, C.; Guillemaud-Mueller, D.; Lhenry, I.; Mueller, A.C.; Scarpaci, J.A.; Sorlin, O.; Mirea, M.

    1999-01-01

    In principle, to produce neutron rich radioactive beams with sufficient intensities, a source of isotopes far from the valley of β--stability can be obtained through the fission of 238 U induced by fast neutrons. A very promising way to assess the feasibility of these very intense neutron beams is to break an intense 2 H beam in a dedicated converter. The main objective of SPIRAL and PARRNe R - D projects is the investigation of the optimum parameters for a neutron rich isotope source in accordance with the scheme presented above. In such conditions, the charge particle energy loss can prevent the destruction of the fission target. In the frame of these project, a special attention is dedicated to the energetic and angular distributions of the neutrons emerging from a set of converters at a series of 2 H incident energies. Deuteron beams at energies less than 30 MeV are particularly interesting because it is expected that, after the decay in the 238 U target, the neutron rich radioactive fission products are cold enough, thus avoiding the evaporation of a too large number of neutrons. For such purposes, one needs experimental angular distributions at given energies for different types of converters and to elaborate a theoretical tool in order to estimate accurately the characteristics of the secondary neutron beam. In this paper, the experimental results were obtained with 17, 20 and 28 MeV deuteron energies on Be, C and U converters using the time of flight method. These data are compared to results given by a model valid at higher energy in order to obtain pertinent simulations in a large range of incident energies. Many theoretical tools were developed to characterize the properties of the neutron beams emerging from thick targets. In this contribution the Serber's model, considered with its improvements which account for the Coulomb deflection and the mean straggling of the beam in the material, is compared to experimental data in order to verify the validity

  20. An examination of the potential for 9%Cr1%Mo steel as thick section tubeplates in fast reactors

    International Nuclear Information System (INIS)

    Orr, J.; Sanderson, S.J.

    1984-01-01

    The steam generator units of future commercial demonstration fast reactors are likely to have a requirement for heavy section tubeplates (up to 500mm thick) with good elevated temperature strength and creep-fatigue resistance. A comparison of the mechanical properties available for ferritic steels has suggested that 9%Cr1%Mo steel would be a strong candidate material for this application. Although this steel is covered in some national specifications for tubes, pipes, plates and forgings and is also well established in the UK nuclear industry, international experience to date is confined to sections less than ca 150mm. The potential of 9%Cr1%Mo steel for use in thick sections has therefore been assessed in the present study by using simulation heat treatments. The work reported here involved the laboratory-scale cooling of bar samples to simulate water-quenching rates in cylindrical sections up to 720mm diameter (ie: equivalent to 500mm thick plate). The tensile properties at ambient and 525 0 C and impact fracture appearance transition temperatures were determined for material tempered after cooling at simulated thick section rates; the transformation characteristics as influenced by the net chromium equivalent were also established. The results of this work show that 9%Cr1%Mo steel may be fully hardened in the equivalent of the section sizes examined,and the mechanical properties of tempered material show only a small reduction from those of thin section normalised and tempered 9%Cr1%Mo steel. These findings support the potential usage of heavy section 9%Cr1%Mo steel envisaged for fast reactor steam generator tubeplates

  1. Fast and low-temperature sintering of silver complex using oximes as a potential reducing agent for solution-processible, highly conductive electrodes

    International Nuclear Information System (INIS)

    Yoo, Ji Hoon; Park, Su Bin; Kim, Ji Man; Han, Dae Sang; Chae, Jangwoo; Kwak, Jeonghun

    2014-01-01

    Highly conductive, solution-processed silver thin-films were obtained at a low sintering temperature of 100 °C in a short sintering time of 10 min by introducing oximes as a potential reductant for silver complex. The thermal properties and reducibility of three kinds of oximes, acetone oxime, 2-butanone oxime, and one dimethylglyoxime, were investigated as a reducing agent, and we found that the thermal decomposition product of oximes (ketones) accelerated the conversion of silver complex into highly conductive silver at low sintering temperature in a short time. Using the acetone oxime, the silver thin-film exhibited the lowest surface resistance (0.91 Ω sq −1 ) compared to those sing other oximes. The silver thin-film also showed a high reflectance of 97.8%, which is comparable to evaporated silver films. We also demonstrated inkjet printed silver patterns with the oxime-added silver complex inks. (paper)

  2. Fast neutron distributions from Be and C thick targets bombarded with 80 and 160 MeV deuterons

    International Nuclear Information System (INIS)

    Pauwels, N.; Laurent, H.; Clapier, F.; Brandenburg, S.; Beijers, J. P .M.; Zegers, R. G. T.; Lebreton, H.; Saint-Laurent, M.G.; Mirea, M.

    2001-01-01

    Production of fast neutron studies have come to the fore in the past few years because of the great interest for the possible applications of induced fission to produce neutron rich ion beams. In this context, the main objective of the SPIRAL II (Systeme de Production d'Ions Radioactifs Acceleres en Ligne) and PARRNe (Production d'Atomes Radioactifs Riches en Neutrons) R and D projects is the investigation of the feasibility and of the optimum parameters for a neutron rich isotope source. Special attention is dedicated to the energy and angular distributions of the neutrons obtained through deuteron break--up in different types of converters and different incident energies. Analysis and modelling of such behaviors, together with the study of the yields of neutron induced fission, can be used to optimize the productivity of the fissioning target its geometry and designing it accordingly. The present report continues our previous studies realised for 17, 20, 28 and 200 MeV deuteron energies and it is focused on deuteron incident energies of 80 and 160 MeV. In the experiment, the double differential cross section for neutron production induced by 80 and 160 MeV deuterons impinging on thick C and Be targets, in which the incident deuterons were complete stopped, have been measured. The energy of the neutrons was determined from the time--of--flight (TOF) measurement. To obtain an energy resolution of about 4% for the fastest, forward--emitted neutrons, which have approximately beam velocity, the length of the flightpath for the detectors at angles up to 30 angle was chosen to be 6 m. At backward angles, where the neutron energies are lower, a shorter flightpath was chosen. A schematic drawing of the setup is shown. A 100 mm thick Be target and a 70 mm thick C target were used. Results are exemplified with the angular and energy distributions of neutron obtained for Be target at 80 MeV. (authors)

  3. Sintering and densification; new techniques: sinter forging

    International Nuclear Information System (INIS)

    Winnubst, A.J.A.

    1998-01-01

    In this chapter pressure assisted sintering methods will be described. Attention will mainly be paid to sinter forging as a die-wall free uniaxial pressure sintering technique, where large creep strains are possible. Sinter forging is an effective tool to reduce sintering temperature and time and to obtain a nearly theoretically dense ceramic. In this way grain size in tetragonal zirconia ceramics can be reduced down to 100 nm. Another important phenomenon is the reduction of the number density and size of cracks and flaws resulting in higher strength and improved reliability, which is of utmost importance for engineering ceramics. The creep deformation during sinter forging causes a rearrangement of the grains resulting in a reduction of interatomic spaces between grains, while grain boundary (glassy) phases can be removed. The toughness and in some cases the wear resistance is enhanced after sinter forging as a result of the grain-boundary-morphology improvement. (orig.)

  4. Estimation of Antarctic Land-Fast Sea Ice Algal Biomass and Snow Thickness From Under-Ice Radiance Spectra in Two Contrasting Areas

    Science.gov (United States)

    Wongpan, P.; Meiners, K. M.; Langhorne, P. J.; Heil, P.; Smith, I. J.; Leonard, G. H.; Massom, R. A.; Clementson, L. A.; Haskell, T. G.

    2018-03-01

    Fast ice is an important component of Antarctic coastal marine ecosystems, providing a prolific habitat for ice algal communities. This work examines the relationships between normalized difference indices (NDI) calculated from under-ice radiance measurements and sea ice algal biomass and snow thickness for Antarctic fast ice. While this technique has been calibrated to assess biomass in Arctic fast ice and pack ice, as well as Antarctic pack ice, relationships are currently lacking for Antarctic fast ice characterized by bottom ice algae communities with high algal biomass. We analyze measurements along transects at two contrasting Antarctic fast ice sites in terms of platelet ice presence: near and distant from an ice shelf, i.e., in McMurdo Sound and off Davis Station, respectively. Snow and ice thickness, and ice salinity and temperature measurements support our paired in situ optical and biological measurements. Analyses show that NDI wavelength pairs near the first chlorophyll a (chl a) absorption peak (≈440 nm) explain up to 70% of the total variability in algal biomass. Eighty-eight percent of snow thickness variability is explained using an NDI with a wavelength pair of 648 and 567 nm. Accounting for pigment packaging effects by including the ratio of chl a-specific absorption coefficients improved the NDI-based algal biomass estimation only slightly. Our new observation-based algorithms can be used to estimate Antarctic fast ice algal biomass and snow thickness noninvasively, for example, by using moored sensors (time series) or mapping their spatial distributions using underwater vehicles.

  5. Sinterização de filmes espessos de Ba(Ti0,85Zr0,15O3 por varredura laser Laser scanning sintering of Ba(Ti0.85Zr0.15O3 thick films

    Directory of Open Access Journals (Sweden)

    E. Antonelli

    2009-03-01

    Full Text Available São apresentados os resultados de sinterização de filmes espessos de BaTi0,85Zr0,15O3 (BTZ15, depositados pela técnica de eletroforese, utilizando como fonte de calor um laser de CO2. A montagem experimental foi otimizada de modo a permitir a sinterização de filmes com dimensões de até 70 mm de comprimento por 10mm de largura e espessuras variáveis. Os processos térmicos envolvidos durante a varredura contínua a laser atuaram de modo similar à sinterização em duas etapas. Os tempos de patamares em cada etapa foram dependentes da velocidade e do número de varreduras. A temperatura máxima que se pode atingir no filme espesso, durante cada varredura e para uma potência nominal do laser fixa, foi correlacionada com a densidade relativa. Após sinterizados, os filmes apresentaram homogeneidade microestrutural e uma porosidade aparente de ~7%.The results for sintering of BaTi0.85Zr0.15O3 (BTZ15 thick films, deposited by electrophoresis, using as heat source a CO2 laser are presented. The characteristics of the experimental apparatus were optimized in such a way as to allow the sintering of thick films whose dimensions were up to 70 mm in length, 10 mm in width and variable thicknesses. The related thermal process during the continuous laser scanning acted in a similar way as a two-step sintering. The step times in each stage were dependent on the speed and scan number. The maximum temperature that can be achieved in the thick film, during each scanning, and for a fixed rated laser power, was correlated with the relative density. After sintering the films presented a microstructural homogeneity and an apparent porosity of ~7%.

  6. Hydrothermal Cold Sintering

    Science.gov (United States)

    Kang, Xiaoyu

    Solid state sintering transforms particle compact to a physically robust and dense polycrystalline monolith driven by reduction of surface energy and curvature. Since bulk diffusion is required for neck formation and pore elimination, sintering temperature about 2/3 of melting point is needed. It thus places limitations for materials synthesis and integration, and contributes to significant energy consumption in ceramic processing. Furthermore, since surface transport requires lower temperature than bulk processes, grain growth is often rapid and can be undesired for physical properties. For these reasons, several techniques have been developed including Liquid Phase Sintering (LPS), Hot Pressing (HP) and Field Assisted Sintering Technique (FAST), which introduce either viscous melt, external pressure or electric field to speed up densification rates at lower temperature. However, because of their inherent reliability on bulk diffusion, temperatures required are often too high for integrating polymers and non-noble metals. Reduction of sintering temperature below 400 °C would require a different densification mechanism that is based on surface transport with external forces to drive volume shrinkage. Densification method combining uniaxial pressure and solution under hydrothermal condition was first demonstrated by Kanahara's group at Kochi University in 1986 and was brought to our attention by the work of Kahari, etc, from University of Oulu on densification of Li2MoO 4 in 2015. This relatively new process showed promising ultra-low densification temperature below 300 °C, however little was known about its fundamental mechanism and scope of applications, which became the main focus of this dissertation. In this work, a uniaxial hydraulic press, a standard stainless steel 1/2 inch diameter die with heating band were utilized in densifying metal oxides. Applied pressure and sintering temperature were between 100 MPa and 700 MPa and from room temperature to 300

  7. Fast synthesis, formation mechanism, and control of shell thickness of CuS–polystyrene core–shell microspheres

    International Nuclear Information System (INIS)

    Zhao, Li-min; Shao, Xin; Yin, Yi-bin; Li, Wen-zhi

    2012-01-01

    Graphical abstract: Core–shell structure PSt/CuS were prepared using polystyrene which were modified by 3-methacryloxypropyltrimethoxysilane as template. The coating thickness of CuS can be controlled by the amount of 3-methacryloxypropyltrimethoxysilane and the UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS. Highlights: ► Core–shell structure PSt/CuS were prepared using silanol-modified polystyrene microspheres as template. ► The coating thickness of core–shell structure PSt/CuS can be controlled by a simple method. ► The UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS. -- Abstract: The silanol-modified polystyrene microspheres were prepared through dispersion polymerization. Then copper sulfide particles were grown on silanol-modified polystyrene through sonochemical deposition in an aqueous bath containing copper acetate and sulfide, released through the hydrolysis of thioacetamide. The resulting particles were continuous and uniform as characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared, thermogravimetric analysis and UV–vis absorption spectroscopy were used to characterize the structure and properties of core–shell particles. The results showed the coating thickness of CuS shell can be controlled by the amount of silanol and the UV–vis absorption intensity of PSt/CuS composite also changed with the coating thickness of CuS.

  8. Direct metal laser sintering: a digitised metal casting technology.

    Science.gov (United States)

    Venkatesh, K Vijay; Nandini, V Vidyashree

    2013-12-01

    Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons.

  9. Direct Metal Laser Sintering: A Digitised Metal Casting Technology

    OpenAIRE

    Venkatesh, K. Vijay; Nandini, V. Vidyashree

    2013-01-01

    Dental technology is undergoing advancements at a fast pace and technology is being imported from various other fields. One such imported technology is direct metal laser sintering technology for casting metal crowns. This article will discuss the process of laser sintering for making metal crowns and fixed partial dentures with a understanding of their pros and cons.

  10. Rapid laser sintering of metal nano-particles inks.

    Science.gov (United States)

    Ermak, Oleg; Zenou, Michael; Toker, Gil Bernstein; Ankri, Jonathan; Shacham-Diamand, Yosi; Kotler, Zvi

    2016-09-23

    Fast sintering is of importance in additive metallization processes and especially on sensitive substrates. This work explores the mechanisms which set limits to the laser sintering rate of metal nano-particle inks. A comparison of sintering behavior of three different ink compositions with laser exposure times from micro-seconds to seconds reveals the dominant factor to be the organic content (OC) in the ink. With a low OC silver ink, of 2% only, sintering time falls below 100 μs with resistivity <×4 bulk silver. Still shorter exposure times result in line delamination and deformation with a similar outcome when the OC is increased.

  11. FAST

    DEFF Research Database (Denmark)

    Zuidmeer-Jongejan, Laurian; Fernandez-Rivas, Montserrat; Poulsen, Lars K.

    2012-01-01

    ABSTRACT: The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections with aqu...

  12. Association of fasting triglyceride concentration and postprandial triglyceride response with the carotid intima-media thickness in the middle aged: The Netherlands Epidemiology of Obesity study.

    Science.gov (United States)

    Christen, Tim; de Mutsert, Renée; Gast, Karin B; Rensen, Patrick C N; de Koning, Eelco; Rosendaal, Frits R; Trompet, Stella; Jukema, J Wouter

    People are in a postprandial state for the majority of the day, postprandial triglyceride (TG) response may be more important in the etiology of atherosclerosis than fasting TGs. The objective of the study was to investigate the associations of fasting TG concentration (TGc) and postprandial TG response after a meal challenge with subclinical atherosclerosis, measured by intima-media thickness (IMT) in a middle-aged population. A total of 5574 participants (57% women) with a mean (standard deviation [SD]) age of 56 (6) years were included in this cross-sectional analysis of baseline measurements of The Netherlands Epidemiology of Obesity study. Serum TGc was measured fasting and 30 and 150 minutes after a liquid mixed meal, and the incremental area under the curve (TGiAUC) was calculated. With linear regression analyses, we calculated the differences in IMT with 95% confidence intervals, adjusted for confounding factors, and additionally for TGc or TGiAUC. Per SD of TGc (0.82 mmol/L), IMT was 8.5 μm (2.1, 14.9) greater after adjustment for TGiAUC and confounding factors. Per SD of TGiAUC (24.0 mmol/L × min), the difference in IMT was -1.7 μm (-8.5, 5.0) after adjustment for fasting TG and confounding factors. The association between TG response after a mixed meal and IMT disappeared after adjusting for TGc. The association between fasting TG concentration and IMT persisted after adjustment for postprandial TG response. These findings imply that it is not useful to perform a meal challenge in cardiovascular risk stratification. Our results support use of fasting TGc instead of postprandial TG responses for cardiovascular risk stratification in clinical practice. Copyright © 2017 National Lipid Association. Published by Elsevier Inc. All rights reserved.

  13. Role of Thickness Confinement on Relaxations of the Fast Component in a Miscible A/B Blend

    Energy Technology Data Exchange (ETDEWEB)

    Green, Peter [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Sharma, Ravi P. [University of Michigan; Dong, Ban Xuan [University of Michigan

    2018-01-18

    Spatial compositional heterogeneity strongly influences the dynamics of the A and B components of bulk miscible blends. Its effects are especially apparent in mixtures, such as poly(vinyl methyl ether) (PVME)/polystyrene (PS), where there exist significant disparities between the component glass transition temperatures (Tgs) and relaxation times. The relaxation processes characterized by distinct temperature dependencies and relaxation rates manifest different local compositional environments for temperatures above and below the glass transition temperature of the miscible blend. This same behavior is shown to exist in miscible PS/PVME films as thin as 100 nm. Moreover, in thin films, the characteristic segmental relaxation times t of the PVME component of miscible PVME/PS blends confined between aluminum (Al) substrates decrease with increasing molecular weight M of the PS component. These relaxation rates are film thickness dependent, in films up to a few hundred nanometers in thickness. This is in remarkable contrast to homopolymer films, where thickness confinement effects are apparent only on length scales on the order of nanometers. These surprisingly large length scales and M dependence are associated with the preferential interfacial enrichment - wetting layer formation - of the PVME component at the external Al interfaces, which alters the local spatial blend composition within the interior of the film. The implications are that the dynamics of miscible thin film blends are dictated in part by component Tg differences, disparities in component relaxation rates, component-substrate interactions, and chain lengths (entropy of mixing).

  14. Microwave sintering of ZnO nanopowders and characterization for gas sensing

    International Nuclear Information System (INIS)

    Bai Zikui; Xie Changsheng; Zhang Shunping; Xu Weilin; Xu Jie

    2011-01-01

    Thick film gas sensors based on ZnO nanopowders were fabricated by using microwave sintering. The surface and cross section morphologies were characterized by field-emission scanning electron microscopy (FE-SEM). The stability of the microstructure was studied by impedance spectroscopy. The results showed that the shape of the nanoparticles was not changed through microwave sintering, and the thick films had the more dense microstructures than that by muffle oven sintering. The resistance-temperature characteristic and the responses to toluene, methanol and formaldehyde revealed that the microwave sintering technique could effectively control the growth of ZnO nanoparticles, realize the uniform sintering of thick film, gain the stable microstructure and improve the response of sensor. In addition, the formative mechanism of the thick film microstructure was proposed according to microwave sintering mechanism.

  15. Sintering of nonstoichiometric UO2

    International Nuclear Information System (INIS)

    Susnik, D.; Holc, J.

    1983-01-01

    Activated sintering of UO 2 pellets at 1100 deg C is described. In CO 2 atmosphere is UO 2 is nonstoichiometric and pellets from active UO 2 powders sinter at 900 deg C to high density. At 1100 deg C the final sintered density is practically achieved at heating on sintering temperature. After reduction and cooling in H 2 atmosphere which is followed sintering in CO 2 the structure is identical to the structured UO 2 pellets sintered at high temperature in H 2 . Density of activated sintered UO 2 pellets is stable, even after additional sintering at 1800 deg C. (author)

  16. Large-area, lightweight and thick biomimetic composites with superior material properties via fast, economic, and green pathways.

    Science.gov (United States)

    Walther, Andreas; Bjurhager, Ingela; Malho, Jani-Markus; Pere, Jaakko; Ruokolainen, Janne; Berglund, Lars A; Ikkala, Olli

    2010-08-11

    Although remarkable success has been achieved to mimic the mechanically excellent structure of nacre in laboratory-scale models, it remains difficult to foresee mainstream applications due to time-consuming sequential depositions or energy-intensive processes. Here, we introduce a surprisingly simple and rapid methodology for large-area, lightweight, and thick nacre-mimetic films and laminates with superior material properties. Nanoclay sheets with soft polymer coatings are used as ideal building blocks with intrinsic hard/soft character. They are forced to rapidly self-assemble into aligned nacre-mimetic films via paper-making, doctor-blading or simple painting, giving rise to strong and thick films with tensile modulus of 45 GPa and strength of 250 MPa, that is, partly exceeding nacre. The concepts are environmentally friendly, energy-efficient, and economic and are ready for scale-up via continuous roll-to-roll processes. Excellent gas barrier properties, optical translucency, and extraordinary shape-persistent fire-resistance are demonstrated. We foresee advanced large-scale biomimetic materials, relevant for lightweight sustainable construction and energy-efficient transportation.

  17. Uranium dioxide sintering Kinetics and mechanisms under controlled oxygen potentials

    International Nuclear Information System (INIS)

    Freitas, C.T. de.

    1980-06-01

    The initial, intermediate, and final sintering stages of uranium dioxide were investigated as a function of stoichiometry and temperature by following the kinetics of the sintering reaction. Stoichiometry was controlled by means of the oxygen potential of the sintering atmosphere, which was measured continuously by solid-state oxygen sensors. Included in the kinetic study were microspheres originated from UO 2 gels and UO 2 pellets produced by isostatic pressing ceramic grade powders. The microspheres sintering behavior was examined using hot-stage microscopy and a specially designed high-temperature, controlled atmosphere furnace. This same furnace was employed as part of an optical dilatometer, which was utilized in the UO 2 pellet sintering investigations. For controlling the deviations from stoichiometry during heat treatment, the oxygen partial pressure in the sintering atmosphere was varied by passing the gas through a Cu-Ti-Cu oxygen trap. The trap temperature determined the oxygen partial pressure of the outflowing mixture. Dry hydrogen was also used in some of the UO sub(2+x) sintering experiments. The determination of diametrial shrinkages and sintering indices was made utilizing high-speed microcinematography and ultra-microbalance techniques. It was observed that the oxygen potential has a substantial influence on the kinetics of the three sintering stages. The control of the sintering atmosphere oxygen partial pressure led to very fast densification of UO sub(2+x). Values in the interval 95.0 to 99.5% of theoretical density were reached in less than one minute. Uranium volume diffusion is the dominant mechanism in the initial and intermediate sintering stages. For the final stage, uranium grain boundary diffusion was found to be the main sintering mechanism. (Author) [pt

  18. Sintering of beryllium oxide

    International Nuclear Information System (INIS)

    Caillat, R.; Pointud, R.

    1955-01-01

    This study had for origin to find a process permitting to manufacture bricks of beryllium oxide of pure nuclear grade, with a density as elevated as possible and with standardized shape. The sintering under load was the technique kept for the manufacture of the bricks. Because of the important toxicity of the beryllium oxide, the general features for the preliminary study of the sintering, have been determined while using alumina. The obtained results will be able to act as general indication for ulterior studies with sintering under load. (M.B.) [fr

  19. Fixation of split-thickness skin graft using fast-clotting fibrin glue containing undiluted high-concentration thrombin or sutures: a comparison study.

    Science.gov (United States)

    Han, Hyun Ho; Jun, Daiwon; Moon, Suk-Ho; Kang, In Sook; Kim, Min Cheol

    2016-01-01

    For skin defects caused by full-thickness burns, trauma, or tumor tissue excision, skin grafting is one of the most convenient and useful treatment methods. In this situation, graft fixation is important in skin grafting. This study was performed to compare the effectiveness of skin graft fixation between high-concentration fibrin sealant and sutures. There have been numerous studies using fibrin sealant for graft fixation, but they utilized slow-clotting fibrin sealant containing less than 10 IU/mL thrombin. Twenty-five patients underwent split-thickness skin grafting using fast-clotting fibrin sealant containing 400 IU/mL thrombin, while 30 patients underwent grafting using sutures. Rates of hematoma/seroma formation, graft dislocation, graft necrosis, and graft take were investigated postoperatively. The graft surface area was calculated using Image J software (National Institutes of Health, Bethesda, MD, USA). After 5 days, rates of hematoma/seroma formation and graft dislocation were 7.84 and 1.29% in group I, and 9.55 and 1.45% in group II, respectively. After 30 days, rates of graft necrosis and graft take were 1.86 and 98.14% in group I, and 4.65 and 95.35% in group II. Undiluted fibrin sealant showed significantly superior results for all rates ( p  < 0.05) except graft dislocation. When high-concentration fast-clotting fibrin sealant was applied to skin grafts without dilution, no difficulty was experienced during surgery. Sealant showed superior results compared with sutures and had an excellent graft take rate. II.

  20. Science of sintering

    International Nuclear Information System (INIS)

    Kuczynski, G.

    1977-01-01

    Although the methods of integration of materials by sintering, have been used since the early history of humanity, the actual understanding of the process involved came only in the last three decades. As in the most human endeavors, the art preceded theory. The comprehension of the elementary processes occuring during sintering comes from the studies of model system. Although the elementary processes occuring during sintering are today quite well understood, the problem of shrinkage of a powder compact which was at the origin of Sintering Science is still far from solved. This is due to the complexity of the internal geometry of the compacts. The recent attempts to apply statistics to this problem, seem to offer some promise

  1. Uranium dioxide. Sintering test

    International Nuclear Information System (INIS)

    Anon.

    Description of a sintering method and of the equipment devoted to uranium dioxide powder caracterization and comparison between different samples. Determination of the curve giving specific volume versus pressure and micrographic examination of a pellet at medium pressure [fr

  2. Kinetics of UO2 sintering

    International Nuclear Information System (INIS)

    Ristic, M.M.

    1962-01-01

    Detailed conclusions related to the UO 2 sintering can be drawn from investigating the kinetics of the sintering process. This report gives an thorough analysis of the the data concerned with sintering available in the literature taking into account the Jander and Arrhenius laws. This analysis completes the study of influence of the O/U ratio and the atmosphere on the sintering. Results presented are fundamentals of future theoretical and experimental work related to characterisation of the UO 2 sintering process

  3. Association between carotid intima-media thickness and fasting blood glucose level: A population-based cross-sectional study among low-income adults in rural China.

    Science.gov (United States)

    Gao, Liu; Bai, Lingling; Shi, Min; Ni, Jingxian; Lu, Hongyan; Wu, Yanan; Tu, Jun; Ning, Xianjia; Wang, Jinghua; Li, Yukun

    2017-11-01

    Carotid intima-media thickness (CIMT) is an established predictor of cardiovascular disease and stroke. We aimed to identify the association between CIMT and blood glucose, as well as the risk factors associated with increased CIMT in a low-income Chinese population. Stroke-free and cardiovascular disease-free residents aged ≥45 years were recruited. B-mode ultrasonography was carried out to measure CIMT. There were 2,643 participants (71.0%) in the normal group, 549 (14.7%) in the impaired fasting glucose group and 533 (14.3%) in the diabetes mellitus group. The determinants of increased CIMT were older age; male sex; low education; hypertension; smoking; high levels of systolic blood pressure, fasting blood glucose and low-density lipoprotein cholesterol; and low levels of diastolic blood pressure, triglycerides and high-density lipoprotein cholesterol, after adjusting for covariates. Age and hypertension were the common risk factors for increased CIMT in all three groups. Furthermore, male sex, smoking and high low-density lipoprotein cholesterol level were positively associated with the mean CIMT in the normal group; high triglycerides levels were negatively associated with the mean CIMT in the impaired fasting glucose group; and alcohol consumption was an independent risk factor for mean CIMT in the diabetes mellitus group. Hypertension was the greatest risk factor for increased CIMT. These findings suggest that it is crucial to manage and control traditional risk factors in low-income populations in China in order to decelerate the recent dramatic increase in stroke incidence, and to reduce the burden of stroke. © 2017 The Authors. Journal of Diabetes Investigation published by Asian Association for the Study of Diabetes (AASD) and John Wiley & Sons Australia, Ltd.

  4. Sintering Theory and Practice

    Science.gov (United States)

    German, Randall M.

    1996-01-01

    Although sintering is an essential process in the manufacture of ceramics and certain metals, as well as several other industrial operations, until now, no single book has treated both the background theory and the practical application of this complex and often delicate procedure. In Sintering Theory and Practice, leading researcher and materials engineer Randall M. German presents a comprehensive treatment of this subject that will be of great use to manufacturers and scientists alike. This practical guide to sintering considers the fact that while the bonding process improves strength and other engineering properties of the compacted material, inappropriate methods of control may lead to cracking, distortion, and other defects. It provides a working knowledge of sintering, and shows how to avoid problems while accounting for variables such as particle size, maximum temperature, time at that temperature, and other problems that may cause changes in processing. The book describes the fundamental atomic events that govern the transformation from particles to solid, covers all forms of the sintering process, and provides a summary of many actual production cycles. Building from the ground up, it begins with definitions and progresses to measurement techniques, easing the transition, especially for students, into advanced topics such as single-phase solid-state sintering, microstructure changes, the complications of mixed particles, and pressure-assisted sintering. German draws on some six thousand references to provide a coherent and lucid treatment of the subject, making scientific principles and practical applications accessible to both students and professionals. In the process, he also points out and avoids the pitfalls found in various competing theories, concepts, and mathematical disputes within the field. A unique opportunity to discover what sintering is all about--both in theory and in practice What is sintering? We see the end product of this thermal

  5. Nanostructured MgTiO{sub 3} thick films obtained by electrophoretic deposition from nanopowders prepared by solar PVD

    Energy Technology Data Exchange (ETDEWEB)

    Apostol, Irina [S.C. IPEE Amiral Trading Impex S.A., 115300 Curtea de Arges (Romania); Mahajan, Amit [Department of Materials and Ceramics Engineering, Centre for Research in Ceramics and Composite Materials, CICECO, University of Aveiro, 3810-093 Aveiro (Portugal); Monty, Claude J.A. [CNRS-PROMES Laboratory, 66120 Font Romeu Odeillo (France); Venkata Saravanan, K., E-mail: venketvs@cutn.ac.in [Department of Materials and Ceramics Engineering, Centre for Research in Ceramics and Composite Materials, CICECO, University of Aveiro, 3810-093 Aveiro (Portugal); Department of Physics, School of Basic and Applied Science, Central University of Tamil Nadu, Thiruvarur 61010 (India)

    2015-12-15

    Highlights: • Obtaining nano-crystalline magnesium titanium oxide powders by solar physical vapor deposition (SPVD) process. And using these nano-powders to obtain thick films on conducting substrates by electrophoretic deposition (EPD). • SPVD is a core innovative, original and environmentally friendly process to prepare nano-materials in a powder form. • Sintered thick films exhibited dielectric constant, ε{sub r} ∼18.3 and dielectric loss, tan δ ∼0.0012 at 1 MHz, which is comparable to the values reported earlier. • New contributions to the pool of information on the preparation of nano-structured MgTiO{sub 3} thick films at low temperatures. • A considerable decrease in synthesis temperature of pure MgTiO{sub 3} thick film was observed by the combination of SPVD and EPD. - Abstract: A novel combination of solar physical vapor deposition (SPVD) and electrophoretic deposition (EPD) that was developed to grow MgTiO{sub 3} nanostructured thick films is presented. Obtaining nanostructured MgTiO{sub 3} thick films, which can replace bulk ceramic components, a major trend in electronic industry, is the main objective of this work. The advantage of SPVD is direct synthesis of nanopowders, while EPD is simple, fast and inexpensive technique for preparing thick films. SPVD technique was developed at CNRS-PROMES Laboratory, Odeillo-Font Romeu, France, while the EPD was performed at University of Aveiro – DeMAC/CICECO, Portugal. The nanopowders with an average crystallite size of about 30 nm prepared by SPVD were dispersed in 50 ml of acetone in basic media with addition of triethanolamine. The obtained well-dispersed and stable suspensions were used for carrying out EPD on 25 μm thick platinum foils. After deposition, films with thickness of about 22–25 μm were sintered in air for 15 min at 800, 900 and 1000 °C. The structural and microstructural characterization of the sintered thick films was carried out using XRD and SEM, respectively. The

  6. Morphological analysis and modelling of sintering and of sintered materials

    International Nuclear Information System (INIS)

    Jernot, Jean-Paul

    1982-01-01

    This research thesis addresses the study of solid phase sintering of metallic powders, and aims at describing as precisely as possible the different involved matter transport mechanisms, first by using a thermodynamic approach to sintering. Sintering diagrams are also used to determine prevailing mechanisms. The microstructure of sintered materials has been studied by using image quantitative analysis, thus by using a morphological approach to sintering. Morphological parameters allow, on the one hand, the evolution of powders during sintering to be followed, and, on the other hand, sintered products to be correctly characterised. Moreover, the author reports the study of the evolution of some physical properties of sintered materials with respect to their microstructure parameters. This leads to the development of a modelling of the behaviour of these materials [fr

  7. Sintering of Synroc D

    International Nuclear Information System (INIS)

    Robinson, G.

    1982-01-01

    Sintering has been investigated as a method for the mineralization and densification of high-level nuclear defense waste powder. Studies have been conducted on Synroc D composite powder LS04. Optimal densification has been found to be highly dependent on the characteristics of the starting material. Powder subjected to milling, which was believed to reduce the level of agglomeration and possibly particle size, was found to densify better than powder not subjected to this milling. Densities of greater than 95% of theoretical could be achieved for samples sintered at 1150 to 1200 0 C. Mineralogy was found to be as expected for Synroc D for samples sintered in a CO 2 /CO atmosphere where the Fe +2 /Fe +3 ratio was maintained at 1.0 to 5.75. In a more oxidizing, pure CO 2 atmosphere a new phase, not previously identified in Synroc D, was found

  8. Sintering of composite

    International Nuclear Information System (INIS)

    Bordia, R.K.; Scherer, G.W.

    1988-01-01

    Several constitutive laws have been used in the literature to predict the response of sintering bodies under external and internal stress fields. These analyses are based on the assumptions of linear and isotropic behavior. The authors provide a critical examination of these equations and show that some of the available constitutive laws predict a negative Poisson's ratio. These laws have been used to analyze sintering of ceramic matrix composites with rigid inclusions and predict large values of the internal stresses and significant retardation of the densification of composites. Since a negative value of Poisson's ratio has never been observed in sinter - forging experiments, the authors conclude that either the stresses are small (as predicted by the constitutive laws with positive Poisson's ratio) or the basic assumption of linearity and isotropy used in all the analyses is incorrect. Finally, the authors discuss some phenomena that could be important in understanding the densification of ceramic matrix composites

  9. Constrained sintering of an air-plasma-sprayed thermal barrier coating

    International Nuclear Information System (INIS)

    Cocks, A.C.F.; Fleck, N.A.

    2010-01-01

    A micromechanical model is presented for the constrained sintering of an air-plasma-sprayed, thermal barrier coating upon a thick superalloy substrate. The coating comprises random splats with intervening penny-shaped cracks. The crack faces make contact at asperities, which progressively sinter in-service by interfacial diffusion, accommodated by bulk creep. Diffusion is driven by the reduction in interfacial energy at the developing contacts and by the local asperity contact stress. At elevated operating temperature, both sintering and creep strains accumulate within the plane of the coating. The sensitivities of sintering rate and microstructure evolution rate to the kinetic parameters and thermodynamic driving forces are explored. It is demonstrated that the sintering response is governed by three independent timescales, as dictated by the material and geometric properties of the coating. Finally, the role of substrate constraint is assessed by comparing the rate of constrained sintering with that for free sintering.

  10. Quartz crystal reinforced quartz glass by spark plasma sintering

    International Nuclear Information System (INIS)

    Torikai, D.; Barazani, B.; Ono, E.; Santos, M.F.M.; Suzuki, C.K.

    2011-01-01

    The Spark Plasma Sintering presents fast processing time when compared to conventional sintering techniques. This allows to control the grain growth during sintering as well as the diffusion rate of a multi-material compounds, and make possible obtainment of functionally graded materials and nanostructured compounds. Powders of high purity silica glass and crystalline silica were sintered in a SPS equipment at temperatures around 1350° C, i.e., above the softening temperature of silica glass and below the melting temperature of quartz crystal. As a result, glass ceramics with pure silica glass matrix reinforced with crystalline alpha-quartz grains were fabricated at almost any desired range of composition, as well as controlled size of the crystalline reinforcement. X-ray diffraction and density measurements showed the possibility to manufacture a well controlled density and crystallinity glass-ceramic materials. (author)

  11. Influence of sintering atmospheres on the aluminium sintering characteristics

    International Nuclear Information System (INIS)

    Mintzer, S.; Bermudez Belkys, S.

    1993-01-01

    This paper describes the aluminium powder (Al) cool compacted (at 95% from theoretical density) which was sintered at 903 K during 4 hours at different atmospheres; oxidizing (air), inert Argon (Ar), Nitrogen (N) and high vacuum. The results obtained show: a) porosity measurements; greater porosity when sintering in Ar and air. b) Metallographic and Scanning observations: many fine pores (< 1 μm) and pore lines distributed at random, at air sintering and greater pores distributed preferentially near the surface, in Ar and N atmospheres. c) Dimensional changes: tendency to contraction of the samples at N and vacuum sintering and expansion in Ar or air. d) Mechanical properties: greater strength and fluence stresses at air and N sintering. The analysis of the results is performed considering sintering modes in presence of an oxide layer and dropped inert gases. (Author)

  12. Physics and Technology of Transparent Ceramic Armor: Sintered Al2O3 vs Cubic Materials

    National Research Council Canada - National Science Library

    Krell, Andreas; Hutzler, Thomas; Klimke, Jens

    2006-01-01

    Sintered sub-micrometer alumina (alpha-Al2O3) is the hardest transparent armor. However, its trigonal structure gives rise to a strong thickness effect that makes thicker components translucent. Cubic ceramics (no birefringence...

  13. Method to produce sintered carriers for electrodes of galvanic elements

    Energy Technology Data Exchange (ETDEWEB)

    Jost, E M

    1978-03-24

    Carrier plates of precisely uniform thickness can be produced according to the invention by firstly thickening a solution of polyethylene oxide and (preferably) methanol by adding water and then, by adding nickel powder, obtaining an essentially homogeneous suspension of considerable viscosity. This slurry is coated on both sides of a nickel grid, dried and sintered.

  14. Characteristics Of The Porous Body Sintered By Nano-Sized Fe-Cr-Al Alloy Powder

    Directory of Open Access Journals (Sweden)

    Lee Su-In

    2015-06-01

    Full Text Available Porous metal with uniform honeycomb structure was successfully produced by sintering using Fe-Cr-Al nano powder, which was prepared by the pulsed wire evaporation (PWE in ethanol. Its process consisted of the several steps; 1 coating on the surface of polyurethane sponge with the liquid droplets generated from the ethanol-based slurry where the Fe-Cr-Al nano powders were uniformly dispersed, 2 heat treatment of debinding to remove the polyurethane sponge and 3 sintering of the porous green body formed by Fe-Cr-Al nano powders. The strut thickness of porous Fe-Cr-Al was increased by the increase of spraying times in ESP step. Also, The shrinkages and the oxidation resistance of the sintered porous body was increased with increase of sintering temperature. The optimal sintering temperature was shown to 1450°C in views to maximize the oxidation resistance and sinterability.

  15. Study on Sintering Mechanism of Stainless Steel Fiber Felts by X-ray Computed Tomography

    Directory of Open Access Journals (Sweden)

    Jun Ma

    2016-01-01

    Full Text Available The microstructure evolution of Fe-17 wt. % Cr-12 wt. % Ni-2 wt. % Mo stainless steel fiber felts during the fast sintering process was investigated by the synchrotron radiation X-ray computed tomography technique. The equation of dynamics of stable inter-fiber neck growth was established for the first time based on the geometry model of sintering joints of two fibers and Kucsynski’s two-sphere model. The specific evolutions of different kinds of sintering joints were observed in the three-dimensional images. The sintering mechanisms during sintering were proposed as plastic flow and grain boundary diffusion, the former leading to a quick growth of sintering joints.

  16. Analysis of Laser Sintering Technology

    Directory of Open Access Journals (Sweden)

    Vladislav Markovič

    2014-02-01

    Full Text Available The new, high-tech development and customization is one ofthe most important factors in promoting the country‘s economicgrowth indicators. The economic downturn in the industryrequires technology and equipment using a minimumof raw materials and providing maximum performance. Thisstatement perfectly describes the innovative, forward-looking,cost-effective laser powder sintering (SLS technology. Here,thanks to the latest engineering achievements, product surfacesare modified and improved, they gain new characteristics. SLSis viable in automobile, engineering, construction, aerospace,aircraft, printing, medical and other areas.In order to create a product which meets the standards andtechnical documentation it is necessary to use and ensure highquality of raw materials, high-end equipment, qualified personnel,the working environment with proper climatic conditions, ergonomics,etc. But all of these, the quality of the product becomesthe decisive indicators meaningless if know how to properly selectthe laser processing operation. Scanning speed, beam power,pulse frequency, protective gases, powder layer thickness – allof them are the physical and mechanical characteristics of thechange in a small range changes the quality of the product of thefuture, the field of application and performance characteristics.

  17. Boric oxide or boric acid sintering aid for sintering ceramics

    International Nuclear Information System (INIS)

    Lawler, H.A.

    1979-01-01

    The invention described relates to the use of liquid sintering aid in processes involving sintering of ceramic materials to produce dense, hard articles having industrial uses. Although the invention is specifically discussed in regard to compositions containing silicon carbide as the ceramic material, other sinterable carbides, for example, titanium carbide, may be utilized as the ceramic material. A liquid sintering aid for densifying ceramic material is selected from solutions of H 3 BO 3 , B 2 O 3 and mixtures of these solutions. In sintering ceramic articles, e.g. silicon carbide, a shaped green body is formed from a particulate ceramic material and a resin binder, and the green body is baked at a temperature of 500 to 1000 0 C to form a porous body. The liquid sintering aid of B 2 O 3 and/or H 3 BO 3 is then dispersed through the porous body and the treated body is sintered at a temperature of 1900 to 2200 0 C to produce the sintered ceramic article. (U.K.)

  18. Association of fasting triglyceride concentration and postprandial triglyceride response with the carotid intima-media thickness in the middle aged : The Netherlands Epidemiology of Obesity study

    NARCIS (Netherlands)

    Christen, Tim; de Mutsert, Renée; Gast, Karin B; Rensen, Patrick C N; de Koning, Eelco; Rosendaal, Frits R; Trompet, Stella; Jukema, J Wouter

    2017-01-01

    BACKGROUND: People are in a postprandial state for the majority of the day, postprandial triglyceride (TG) response may be more important in the etiology of atherosclerosis than fasting TGs. OBJECTIVE: The objective of the study was to investigate the associations of fasting TG concentration (TGc)

  19. Flash sintering of ceramic materials

    Science.gov (United States)

    Dancer, C. E. J.

    2016-10-01

    During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sintering methods carried out to date, and compares the properties of the materials obtained to those produced by conventional sintering. The flash sintering process is described for oxides of zirconium, yttrium, aluminium, tin, zinc, and titanium; silicon and boron carbide, zirconium diboride, materials for solid oxide fuel applications, ferroelectric materials, and composite materials. While experimental observations have been made on a wide range of materials, understanding of the underlying mechanisms responsible for the onset and latter stages of flash sintering is still elusive. Elements of the proposed theories to explain the observed behaviour include extensive Joule heating throughout the material causing thermal runaway, arrested by the current limitation in the power supply, and the formation of defect avalanches which rapidly and dramatically increase the sample conductivity. Undoubtedly, the flash sintering process is affected by the electric field strength, furnace temperature and current density limit, but also by microstructural features such as the presence of second phase particles or dopants and the particle size in the starting material. While further experimental work and modelling is still required to attain a full understanding capable of predicting the success of the flash sintering process in different materials, the technique non-etheless holds great potential for exceptional control of the ceramic sintering process.

  20. Pressure sintering and creep deformation: a joint modeling approach

    International Nuclear Information System (INIS)

    Notis, M.R.

    1979-10-01

    Work related to microchemical and microstructural aspects of the joint modeling of pressure sintering and creep in ceramic oxides is reported. Quantitative techniques for the microchemical analysis of ceramic oxides and for the examination of impurity segregation effects in polycrystalline ceramic materials were developed. This has included fundamental absorption corrections for the oxygen anion species as a function of foil thickness. The evolution in microstructure during the transition from intermediate stage to final stage densification during hot pressing of cobalt oxide and preliminary studies with doped oxides were studied. This work shows promise in using time-integrated microstructural effects to elucidate the role of impurities in the sintering of ceramic materials

  1. Mechanisms of sintering

    International Nuclear Information System (INIS)

    Mohan, Ashok; Soni, N.C.; Moorthy, V.K.

    1980-01-01

    The basic mechanisms by which the material moves during sintering have not only held a strange fascination but are also very important in determining the properties of the end product. Kuczynski's exponent method has been subsequently refined by several schools to make it increasingly reliable. There is now a fairly good understanding of mechanisms in some of the materials. However in others the issue is complicated by their basic nature. The problems of ambiguity in criterion and that of more than one mechanism being simultaneously operative have been tackled with dexterity by Ashby for drawing sintering mechanism diagrams. The method has been modified to give Relative Contribution Diagrams (RCD). These yield additional information and have been used for analysis. The main criticism against this is that it uses a very large number of rate equations and material properties, which can communicate their inaccuracies to the diagram. A case study of UO 2 was undertaken and it has been shown quantitatively that inaccuracies in a smaller number of properties only affect the diagrams to any significant extent. (auth.)

  2. [Association between the level of fasting blood glucose over 35-year-old and carotid intima-media thickness in Han, Uygur and Kazak population from Xinjiang Uygur Autonomous Region from 2007 to 2010].

    Science.gov (United States)

    Li, Xiaomei; Li, Haixia; Liu, Fen; Chen, Bangdang; Yang, Yining; Ma, Yitong

    2014-10-01

    To analyze the relationship between different levels of fasting blood glucose over 35-year old and carotid intima-media thickness (IMT) in Han, Uygur and Kazak adult population from Xinjiang Uygur Autonomous Region. From October 2007 to April 2010, the present study was performed in 13 935 inhabitants among Han, Uygur and Kazak adult population of aged 35 years old and over by multi-stage stratified cluster random sampling principles from 7 regions in Xinjiang Uygur Autonomous and we excluded the IMT over 0.9 millimeter, long-term out and the floating population. All subjects were measured fasting blood glucose and IMT values of carotid artery. The subjects were divided into three groups according to different fasting blood glucose levels: normal, impaired fasting glucose (IFG) and diabetes mellitus (DM) and we used the analysis of variance to compare the differences among groups of IMT. Multiple linear regression model was used to explore factors of carotid IMT. The IMT of males of Han, Uygur and Kazak were (0.81 ± 0.29), (0.71 ± 0.27) and (0.79 ± 0.21) mm respectively, the differences were significant (F = 88.50, P blood pressure (β = 0.101, P blood glucose (β = 0.023, P = 0.009) were independent risk factors of IMT. The level of fasting blood glucose was an independent influence factor of carotid IMT and had a positive correlation in Han, Uygur and Kazak population of Xinjiang Autonomous Region.

  3. Modeling Macroscopic Shape Distortions during Sintering of Multi-layers

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye

    as to help achieve defect free multi-layer components. The initial thickness ratio between the layers making the multi-layer has also significant effect on the extent of camber evolution depending on the material systems. During sintering of tubular bi-layer structures, tangential (hoop) stresses are very...... large compared to radial stresses. The maximum value of hoop stress, which can generate processing defects such as cracks and coating peel-offs, occurs at the beginning of the sintering cycle. Unlike most of the models defining material properties based on porosity and grain size only, the multi...... (firing). However, unintended features like shape instabilities of samples, cracks or delamination of layers may arise during sintering of multi-layer composites. Among these defects, macroscopic shape distortions in the samples can cause problems in the assembly or performance of the final component...

  4. High performance sinter-HIP for hard metals

    International Nuclear Information System (INIS)

    Hongxia Chen; Deming Zhang; Yang Li; Jingping Chen

    2001-01-01

    The horizontal sinter-HIP equipment with great charge capacity and high performance, developed and manufactured by Central Iron and Steel Research Institute(CISRI), is mainly used for sintering and condensation of hard metals. This equipment is characterized by large hot zone, high heating speed, good temperature uniformity and fast cooling system. The equipment can provide uniform hot zone with temperature difference less than 6 o C at 1500-1600 o C and 6-10 MPa by controlling temperature, pressure and circulation of gas precisely. Using large scale horizontal sinter-HIP equipment to produce hard matals have many advantages such as stable quality, high efficiency of production, high rate of finished products and low production cost, so this equipment is a good choice for manufacturer of hard metals. (author)

  5. Production of pure sintered alumina

    International Nuclear Information System (INIS)

    Rocha, J.C. da; Huebner, H.W.

    1982-01-01

    With the aim of optimizing the sintering parameters, the strength of a large number of alumina samples was determined which were produced under widely varying sintering conditions and with different amounts of MgO content. The strength as a function of sintering time or temperature was found to go through a maximum. With increasing time, this maximum is shifted to lower temperatures, and with decreasing temperature to longer times. Data pairs of sintering times and temperatures which yeld the strength maximum were determined. The value of the strength at the maximum remains unchanged. The strength is high (= 400 MN/m 2 , at a grain size of 3 um and a porosity of 2 per cent) and comparable to foreign aluminas produced for commercial purposes, or even higher. The increase in the sintering time from 1 h to 16 h permits a reduction of the sintering temperature from 1600 to 1450 0 C without losing strength. The practical importance of this fact for a production of sintered alumina on a large scale is emphasized. (Author) [pt

  6. Study of Material Moisture Measurement Method and Instrument by the Combination of Fast Neutron Absorption and γ Absorption

    International Nuclear Information System (INIS)

    Hou Chaoqin; Gong Yalin; Zhang Wei; Shang Qingmin; Li Yanfeng; Gou Qiangyuan; Yin Deyou

    2010-01-01

    To solve the problem of on-line sinter moisture measurement in the iron making plant, we developed material moisture measurement method and instrument by the combination of fast neutron absorption and y-absorption. It overcomes the present existed problems of other moisture meters for the sinter. Compare with microwave moisture meter, the measurement dose not affected by conductance and magnetism of material; to infrared moisture meter, the measurement result dose not influenced by colour and light-reflect performance of material surface, dose not influenced by changes of material kind; to slow neutron scatter moisture meter, the measurement dose not affected by density of material and thickness of hopper wall; to the moisture measurement meter which combined by slow neutron penetrate through and y-absorption, there are definite math model and good linear relation between the measurement values, and the measurement dose not affected by material thickness, changes of material form and component. (authors)

  7. Sinterability and microstructure evolution during sintering of ferrous powder mixtures

    Directory of Open Access Journals (Sweden)

    Kétner Bendo Demétrio

    2013-01-01

    Full Text Available The present work is focused on ferrous powder metallurgy and presents some results of a development of a suitable masteralloy for use as an additive to iron powder for the production of sintered steels. The masteralloy was produced by melting a powder mixture containing approximately Fe + 20% Ni + 20% Mn + 20% Si + 1% C (wt%, in order to obtain a cast billet that was converted into fine powder by crushing and milling. It was observed presence of SiC in the masteralloy after melting that is undesirable in the alloy. Si element should be introduced by using ferrosilicon. Sintered alloys with distinct contents of alloying elements were prepared by mixing the masteralloy powder to plain iron powder. Samples were produced by die compaction of the powder mixtures and sintering at 1200 °C in a differential dilatometer in order to record their linear dimensional behaviour during heating up and isothermal sintering, aiming at studying the sinterability of the compacts. Microstructure development during sintering was studied by SEM, XRD and microprobe analyses.

  8. Method of sintering ceramic materials

    Science.gov (United States)

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  9. Diagnostic methods for fast-track identification of endometrial cancer in women with postmenopausal bleeding and endometrial thickness greater than 5 mm

    DEFF Research Database (Denmark)

    Dueholm, Margit; Marinowskij, Edvard; Hansen, Estrid Stæhr

    2015-01-01

    efficiency (area under the curve) for malignancy diagnosis (ES, 0.90; TVS, 0.88; GIS, 0.92; HYpattern, 0.91). When insufficient samples were incorporated, ES was less efficient than the other techniques. ES was not more efficient in the subgroup of women without localized lesions than in the subgroup...... of women with localized lesions. MRI and HYpattern added limited efficiency, whereas hysteroscopy with biopsy was most efficient. CONCLUSIONS: As a first-line technique, pattern recognition on TVS, GIS, and HYpattern correctly identifies 9 of 10 women with malignancy and is superior to pattern recognition...... on ES when insufficient samples are included. Endometrial pattern evaluated with TVS and GIS is a fast and efficient first-line diagnostic tool that outperforms ES in women with or without localized lesions. Malignant patterns on TVS/GIS should warrant fast-track evaluation, whereas women with benign...

  10. Solidification of high level liquid waste (HLLW) into ceramics by sintering process

    International Nuclear Information System (INIS)

    Masuda, Sumio; Oguino, Naohiko; Tsunoda, Naomi; O-oka, Kazuo; Ohta, Takao.

    1979-01-01

    One of the alternatives to vitrified solid which is acceptable and well characterized for storing radioactive HLLW with desirable long-term stability is ceramics. On the other hand, the solidification process of highly radioactive wastes should be simple and suitable for continuous production. On the above described basis, the authors have made preliminary study on the production of sintered ceramics by the addition of several oxides to HLLW. The simulated waste and additive oxides were pressed in a mold to make the preforms of 50 mm diameter and 10 to 15 mm thick. The preforms were then normally sintered at temperature from 1000 to 1400 deg C for 2 to 4 hours. The characterization of the sintered solids revealed the following facts. (1) X-ray diffraction analysis showed that the expected crystals were formed by normal-sintering as well as by hot-pressing. (2) The bulk density of the ceramics by normal-sintering was around 90 to 95% of the assumed theoretical values. (3) The leach-rate of the solids was affected by the bulk density. (4) Other properties of the solids, such as thermal expansion or thermal conductivity, are dominantly determined by those of main crystals in the solids. Sintering process is generally simple and productive as far as normal sintering is concerned. However, hot-pressing is an intermittent and time consuming process. From this fact, the authors intended to adopt the normal sintering process for the ceramic solidification of high level liquid wastes. (Wakatsuki, Y.)

  11. Welding simulation of large-diameter thick-walled stainless steel pipe joints. Fast computation of residual stress and influence of heat source model

    International Nuclear Information System (INIS)

    Maekawa, Akira; Serizawa, Hisashi; Nakacho, Keiji; Murakawa, Hidekazu

    2011-01-01

    There are many weld zones in the apparatus and piping installed in nuclear power plants and residual stress generated in the zone by weld process is the most important influence factor for maintaining structural integrity. Though the weld residual stress is frequently evaluated using numerical simulation, fast simulation techniques have been demanded because of the enormous calculation times used. Recently, the fast weld residual stress evaluation based on three-dimensional accurate analysis became available through development of the Iterative Substructure Method (ISM). In this study, the computational performance of the welding simulation code using the ISM was improved to get faster computations and more accurate welding simulation. By adding functions such as parallel processing, the computation speed was much faster than that of the conventional finite element method code. Furthermore, the accuracy of the improved code was validated by measurements. The influence of two different weld heat source models on the simulation results was also investigated and it was found that the moving heat source was effective to achieve accurate weld simulation for multi-pass welds. (author)

  12. Fast-solving thermally thick model of biomass particles embedded in a CFD code for the simulation of fixed-bed burners

    International Nuclear Information System (INIS)

    Gómez, M.A.; Porteiro, J.; Patiño, D.; Míguez, J.L.

    2015-01-01

    Highlights: • A thermally thick treatment is used to simulate of fuel the thermal conversion of solid biomass. • A dynamic subgrid scale is used to model the advance of reactive fronts inside the particle. • Efficient solution algorithms are applied to calculate the temperatures and volume of the internal layers. • Several tests were simulated and compared with experimental data. - Abstract: The thermally thick treatment of fuel particles during the thermal conversion of solid biomass is required to consider the internal gradients of temperature and composition and the overlapping of the existing biomass combustion stages. Due to the implied mixture of scales, the balance between model resolution and computational efficiency is an important limitation in the simulation of beds with large numbers of particles. In this study, a subgrid-scale model is applied to consider the intraparticle gradients, the interactions with other particles and the gas phase using a Euler–Euler CFD framework. Numerical heat transfer and mass conservation equations are formulated on a subparticle scale to obtain a system of linear equations that can be used to resolve the temperature and position of the reacting front inside the characteristic particle of each cell. To simulate the entire system, this modelling is combined with other submodels of the gas phase, the bed reaction and the interactions. The performance of the new model is tested using published experimental results for the particle and the bed. Similar temperatures are obtained in the particle-alone tests. Although the mass consumption rates tend to be underpredicted during the drying stage, they are subsequently compensated. In addition, an experimental batch-loaded pellet burner was simulated and tested with different air mass fluxes, in which the experimental ignition rates and temperatures are employed to compare the thermally thick model with the thermally thin model that was previously developed by the authors

  13. On the Mechanism of Microwave Flash Sintering of Ceramics

    Directory of Open Access Journals (Sweden)

    Yury V. Bykov

    2016-08-01

    Full Text Available The results of a study of ultra-rapid (flash sintering of oxide ceramic materials under microwave heating with high absorbed power per unit volume of material (10–500 W/cm3 are presented. Ceramic samples of various compositions—Al2O3; Y2O3; MgAl2O4; and Yb(LaO2O3—were sintered using a 24 GHz gyrotron system to a density above 0.98–0.99 of the theoretical value in 0.5–5 min without isothermal hold. An analysis of the experimental data (microwave power; heating and cooling rates along with microstructure characterization provided an insight into the mechanism of flash sintering. Flash sintering occurs when the processing conditions—including the temperature of the sample; the properties of thermal insulation; and the intensity of microwave radiation—facilitate the development of thermal runaway due to an Arrhenius-type dependency of the material’s effective conductivity on temperature. The proper control over the thermal runaway effect is provided by fast regulation of the microwave power. The elevated concentration of defects and impurities in the boundary regions of the grains leads to localized preferential absorption of microwave radiation and results in grain boundary softening/pre-melting. The rapid densification of the granular medium with a reduced viscosity of the grain boundary phase occurs via rotation and sliding of the grains which accommodate their shape due to fast diffusion mass transport through the (quasi-liquid phase. The same mechanism based on a thermal runaway under volumetric heating can be relevant for the effect of flash sintering of various oxide ceramics under a dc/ac voltage applied to the sample.

  14. Sintering diagrams of UO2

    International Nuclear Information System (INIS)

    Mohan, A.; Soni, N.C.; Moorthy, V.K.

    1979-01-01

    Ashby's method (see Acta Met., vol. 22, p. 275, 1974) of constructing sintering diagrams has been modified to obtain contribution diagrams directly from the computer. The interplay of sintering variables and mechanisms are studied and the factors that affect the participation of mechanisms in UO 2 are determined. By studying the physical properties, it emerges that the order of inaccuracies is small in most cases and do not affect the diagrams. On the other hand, even a 10% error in activation energies, which is quite plausible, would make a significant difference to the diagram. The main criticism of Ashby's approach is that the numerous properties and equations used, communicate their inaccuracies to the diagrams and make them unreliable. The present study has considerably reduced the number of factors that need to be refined to make the sintering diagrams more meaningful. (Auth.)

  15. Constrained Sintering in Fabrication of Solid Oxide Fuel Cells.

    Science.gov (United States)

    Lee, Hae-Weon; Park, Mansoo; Hong, Jongsup; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook

    2016-08-09

    Solid oxide fuel cells (SOFCs) are inevitably affected by the tensile stress field imposed by the rigid substrate during constrained sintering, which strongly affects microstructural evolution and flaw generation in the fabrication process and subsequent operation. In the case of sintering a composite cathode, one component acts as a continuous matrix phase while the other acts as a dispersed phase depending upon the initial composition and packing structure. The clustering of dispersed particles in the matrix has significant effects on the final microstructure, and strong rigidity of the clusters covering the entire cathode volume is desirable to obtain stable pore structure. The local constraints developed around the dispersed particles and their clusters effectively suppress generation of major process flaws, and microstructural features such as triple phase boundary and porosity could be readily controlled by adjusting the content and size of the dispersed particles. However, in the fabrication of the dense electrolyte layer via the chemical solution deposition route using slow-sintering nanoparticles dispersed in a sol matrix, the rigidity of the cluster should be minimized for the fine matrix to continuously densify, and special care should be taken in selecting the size of the dispersed particles to optimize the thermodynamic stability criteria of the grain size and film thickness. The principles of constrained sintering presented in this paper could be used as basic guidelines for realizing the ideal microstructure of SOFCs.

  16. Constrained Sintering in Fabrication of Solid Oxide Fuel Cells

    Science.gov (United States)

    Lee, Hae-Weon; Park, Mansoo; Hong, Jongsup; Kim, Hyoungchul; Yoon, Kyung Joong; Son, Ji-Won; Lee, Jong-Ho; Kim, Byung-Kook

    2016-01-01

    Solid oxide fuel cells (SOFCs) are inevitably affected by the tensile stress field imposed by the rigid substrate during constrained sintering, which strongly affects microstructural evolution and flaw generation in the fabrication process and subsequent operation. In the case of sintering a composite cathode, one component acts as a continuous matrix phase while the other acts as a dispersed phase depending upon the initial composition and packing structure. The clustering of dispersed particles in the matrix has significant effects on the final microstructure, and strong rigidity of the clusters covering the entire cathode volume is desirable to obtain stable pore structure. The local constraints developed around the dispersed particles and their clusters effectively suppress generation of major process flaws, and microstructural features such as triple phase boundary and porosity could be readily controlled by adjusting the content and size of the dispersed particles. However, in the fabrication of the dense electrolyte layer via the chemical solution deposition route using slow-sintering nanoparticles dispersed in a sol matrix, the rigidity of the cluster should be minimized for the fine matrix to continuously densify, and special care should be taken in selecting the size of the dispersed particles to optimize the thermodynamic stability criteria of the grain size and film thickness. The principles of constrained sintering presented in this paper could be used as basic guidelines for realizing the ideal microstructure of SOFCs. PMID:28773795

  17. Sintering and microstructure evolution of columnar nickel-based superalloy sheets prepared by EB-PVD

    International Nuclear Information System (INIS)

    Chen, S.; Qu, S.J.; Liang, J.; Han, J.C.

    2010-01-01

    Research highlights: → EB-PVD technology is commonly used to deposit thermal barrier coatings (TBCs) and columnar structure is commonly seen in EB-PVD condensates. The unique columnar structure can provide outstanding resistance against thermal shock and mechanical strains for TBCs. However, a number of researchers have found that the columnar structure can affect the mechanical properties of EB-PVD alloy thin sheet significantly. As yet, works on how to reduce this kind of effects are seldom done. In the present article, we tried to reveal the sintering effects on microstructure evolution and mechanical properties of columnar Ni-based superalloy sheet. The results suggests that after sintering, the columnar structure degrades. Degradation depends on sintering temperature and time. Both the ultimate tensile strength and the elongation percentage are effectively improved after sintering. - Abstract: A ∼0.15 mm-thick columnar nickel-based superalloy sheet was obtained by electron beam physical vapor deposition (EB-PVD). The as-deposited alloy sheet was sintered at different conditions. The microstructure of the specimens before and after sintering was characterized by using scanning electron microscopy. An X'Pert texture facility was used to determine the crystallographic orientation of the as-deposited alloy sheet. The phase transformation was investigated by X-ray diffraction. Tensile tests were conducted at room temperature on as-deposited and sintered specimens. The results show that the as-deposited sheet is composed of typical columnar structures. After sintering, however, the columnar structure degrades. The degradation depends on sintering temperature and time. Both the ultimate tensile strength and the elongation percentage are effectively improved after sintering.

  18. Phosphorus containing sintered alloys (review)

    International Nuclear Information System (INIS)

    Muchnik, S.V.

    1984-01-01

    Phosphorus additives are considered for their effect on the properties of sintered alloys of different applications: structural, antifriction, friction, magnetic, hard, superhard, heavy etc. Data are presented on compositions and properties of phosphorus-containing materials produced by the powder metallurgy method. Phosphorus is shown to be an effective activator of sintering in some cases. When its concentration in the material is optimal it imparts the material such properties as strength, viscosity, hardness, wear resistance. Problems concerning powder metallurgy of amorphous phosphorus-containing alloys are reported

  19. Kinetics of sintering of uranium dioxide

    International Nuclear Information System (INIS)

    Soni, N.C.; Moorthy, V.K.

    1978-01-01

    The kinetics of sintering of UO 2 powders derived from ADU route and calcined at different temperatures was studied. The activation energy for sintering was found to depend on the calcination temperature, the density chosen and the sintering temperature range. The motive force for sintering is the excess free energy in the particle system. This exists in the powder compact in the form of surface energy and the excess lattice energy due to defects. The defects which can be eliminated at the operating temperature are responsible for the mobility and hence sintering. This concept of the motive force for sintering has been used to explain the difference in the activation energies observed in the present study. This would also explain phenomena such as attainment of limiting density, presence of optimum sintering temperature and the influence of calcination treatments on the sintering behaviour of powders. (author)

  20. Recycling of mill scale in sintering process

    Directory of Open Access Journals (Sweden)

    El-Hussiny N.A.

    2011-01-01

    Full Text Available This investigation deals with the effect of replacing some amount of Baharia high barite iron ore concentrate by mill scale waste which was characterized by high iron oxide content on the parameters of the sintering process., and investigation the effect of different amount of coke breeze added on sintering process parameters when using 5% mill scale waste with 95% iron ore concentrate. The results of this work show that, replacement of iron ore concentrate with mill scale increases the amount of ready made sinter, sinter strength and productivity of the sinter machine and productivity at blast furnace yard. Also, the increase of coke breeze leads to an increase the ready made sinter and productivity of the sintering machine at blast furnace yard. The productivity of the sintering machine after 5% decreased slightly due to the decrease of vertical velocity.

  1. Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

    Science.gov (United States)

    Decraene, Carolina; Dijckmans, Arne; Reynders, Edwin P. B.

    2018-05-01

    A method is developed for computing the mean and variance of the diffuse field sound transmission loss of finite-sized layered wall and floor systems that consist of solid, fluid and/or poroelastic layers. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. This hybrid modal transfer matrix-statistical energy analysis method is validated on multiple wall systems: a thin steel plate, a polymethyl methacrylate panel, a thick brick wall, a sandwich panel, a double-leaf wall with poro-elastic material in the cavity, and a double glazing. The predictions are compared with experimental data and with results obtained using alternative prediction methods such as the transfer matrix method with spatial windowing, the hybrid wave based-transfer matrix method, and the hybrid finite element-statistical energy analysis method. These comparisons confirm the prediction accuracy of the proposed method and the computational efficiency against the conventional hybrid finite element-statistical energy analysis method.

  2. Thick Toenails

    Science.gov (United States)

    ... in individuals with nail fungus (onychomycosis), psoriasis and hypothyroidism. Those who have problems with the thickness of their toenails should consult a foot and ankle surgeon for proper diagnosis and treatment. Find an ACFAS Physician Search Search Tools Find ...

  3. Master Sintering Surface: A practical approach to its construction and utilization for Spark Plasma Sintering prediction

    Directory of Open Access Journals (Sweden)

    Pouchly V.

    2012-01-01

    Full Text Available The sintering is a complex thermally activated process, thus any prediction of sintering behaviour is very welcome not only for industrial purposes. Presented paper shows the possibility of densification prediction based on concept of Master Sintering Surface (MSS for pressure assisted Spark Plasma Sintering (SPS. User friendly software for evaluation of the MSS is presented. The concept was used for densification prediction of alumina ceramics sintered by SPS.

  4. SINTERING OF NASCENT CALCIUM OXIDE

    Science.gov (United States)

    The paper discusses the measurement of the sintering rate of CaO in a nitrogen atmosphere at temperatures of 700-1100 C. CaO prepared from ultrapure CaCO3 was compared with an impure CaO derived from limestone. Both materials yielded an initial surface area of 104 sq m/g. The rat...

  5. Modeling the microstructural evolution during constrained sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Frandsen, Henrik Lund; Tikare, V.

    A numerical model able to simulate solid state constrained sintering of a powder compact is presented. The model couples an existing kinetic Monte Carlo (kMC) model for free sintering with a finite element (FE) method for calculating stresses on a microstructural level. The microstructural response...... to the stress field as well as the FE calculation of the stress field from the microstructural evolution is discussed. The sintering behavior of two powder compacts constrained by a rigid substrate is simulated and compared to free sintering of the same samples. Constrained sintering result in a larger number...

  6. Comparative studies on mechanical properties of WC-Co composites sintered by SPS and conventional techniques

    Directory of Open Access Journals (Sweden)

    Pristinskiy Yuri

    2017-01-01

    Full Text Available Spark plasma sintering (SPS is an extremely fast solidification technique for compounds that are difficult to sinter within the material group metals, ceramics, or composites thereof, SPS uses a uniaxial pressure and a very rapid heating cycle to consolidate these materials. With SPS the main benefit is the ability to control the WC grain size due to the short sintering times at high temperature. Additionally, its allows to avoid negative reactions between WC and cobalt and to minimize the formation of undesirable phases in sintered composites. The WC-6wt.% Co cermet prepared by SPS processing achieves the enhanced mechanical properties with the hardness of 18.3 GPa and the fracture toughness of 15.5 MPa·m1/2 in comparison to standard reference tungsten carbide/cobalt material.

  7. Strain-enhanced sintering of iron powders

    Energy Technology Data Exchange (ETDEWEB)

    Amador, D.R.; Torralba, J.M. [Universidad Carlos III de Madrid, Departamento de Ciencias de Materiales e Ingenieria Metalurgica, Leganes, Madrid (Spain); Monge, M.A.; Pareja, R. [Universidad Carlos III de Madrid, Departamento de Fisica, Madrid (Spain)

    2005-02-01

    Sintering of ball-milled and un-milled Fe powders has been investigated using dilatometry, X-ray, density, and positron annihilation techniques. A considerable sintering enhancement is found in milled powders showing apparent activation energies that range between 0.44 and 0.80 eV/at. The positron annihilation results, combined with the evolution of the shrinkage rate with sintering temperature, indicate generation of lattice defects during the sintering process of milled and un-milled powders. The sintering enhancement is attributed to pipe diffusion along the core of moving dislocations in the presence of the vacancy excess produced by plastic deformation. Positron annihilation results do not reveal the presence of sintering-induced defects in un-milled powders sintered above 1200 K, the apparent activation energy being in good agreement with that for grain-boundary diffusion in {gamma}-Fe. (orig.)

  8. Microwave sintering of ceramic materials

    Science.gov (United States)

    Karayannis, V. G.

    2016-11-01

    In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

  9. Modeling of sintering of functionally gradated materials

    International Nuclear Information System (INIS)

    Gasik, M.; Zhang, B.

    2001-01-01

    The functionally gradated materials (FGMs) are distinguished from isotropic materials by gradients of composition, phase distribution, porosity, and related properties. For FGMs made by powder metallurgy, sintering control is one of the most important factors. In this study sintering process of FGMs is modeled and simulated with a computer. A new modeling approach was used to formulate equation systems and the model for sintering of gradated hard metals, coupled with heat transfer and grain growth. A FEM module was developed to simulate FGM sintering in conventional, microwave and hybrid conditions, to calculate density, stress and temperature distribution. Behavior of gradated WC-Co hardmetal plate and cone specimens was simulated for various conditions, such as mean particle size, green density distribution and cobalt gradation parameter. The results show that the deformation behavior and stress history of graded powder compacts during heating, sintering and cooling could be predicted for optimization of sintering process. (author)

  10. Direct laser sintering of metal powders: Mechanism, kinetics and microstructural features

    International Nuclear Information System (INIS)

    Simchi, A.

    2006-01-01

    In the present work, the densification and microstructural evolution during direct laser sintering of metal powders were studied. Various ferrous powders including Fe, Fe-C, Fe-Cu, Fe-C-Cu-P, 316L stainless steel, and M2 high-speed steel were used. The empirical sintering rate data was related to the energy input of the laser beam according to the first order kinetics equation to establish a simple sintering model. The equation calculates the densification of metal powders during direct laser sintering process as a function of operating parameters including laser power, scan rate, layer thickness and scan line spacing. It was found that when melting/solidification approach is the mechanism of sintering, the densification of metals powders (D) can be expressed as an exponential function of laser specific energy input (ψ) as ln(1 - D) = -Kψ. The coefficient K is designated as 'densification coefficient'; a material dependent parameter that varies with chemical composition, powder particle size, and oxygen content of the powder material. The mechanism of particle bonding and microstructural features of the laser sintered powders are addressed

  11. Production of sintered alumina from powder; optimization of the sinterized parameters for the maximum mechanical resistence

    International Nuclear Information System (INIS)

    Rocha, J.C. da.

    1981-02-01

    Pure, sinterized alumina and the optimization of the parameters of sinterization in order to obtain the highest mechanical resistence are discussed. Test materials are sinterized from a fine powder of pure alumina (Al 2 O 3 ), α phase, at different temperatures and times, in air. The microstructures are analysed concerning porosity and grain size. Depending on the temperature or the time of sinterization, there is a maximum for the mechanical resistence. (A.R.H.) [pt

  12. Microwave sintering of hydroxyapatite-based composites

    International Nuclear Information System (INIS)

    Fang, Y.; Roy, D.M.; Cheng, J.; Roy, R.; Agrawal, D.K.

    1993-01-01

    Composites of hydroxyapatite/partially stabilized zirconia (HAp/PSZ) and hydroxyapatite/silicon carbide whiskers (HAp/SiC) were sintered at 1100-1200 degrees C by microwave at 2.45 GHz. Characterization of the sintered composites was carried out by density, microstructure, phase composition, and fracture toughness measurements. The results show that although not yet fully densified, a much higher sintered density in the HAp/PSZ composite was achieved by microwave sintering than by conventional sintering at the same temperature. A relative density of 93% was achieved by 20 min. microwave processing at 1200 degrees C. Comparatively, 2 h conventional sintering of the same material at 1200 degrees C led to only 75.5% relative density. K IC of this microwave sintered HAp/PSZ of 93% density was found to be 3.88 MPa√m, which is 250% of the value for pure HAp of the same density. A further increase in K IC could be expected if full or nearly full densification was achieved. Sintering of PSZ particles in the HAp/PSZ composite was also observed in the microwave processed sample. Microwave sintering of HAp/SiC was not successful in the current study due to the oxidation of SiC in air at high temperature. 8 refs., 4 figs., 1 tab

  13. Sintering of a class F fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Joseph J. Biernacki; Anil K. Vazrala; H. Wayne Leimer [Tennessee Technological University, Cookeville, TN (United States). Department of Chemical Engineering

    2008-05-15

    The sinterability of a class F fly ash was investigated as a function of processing conditions including sintering temperature (1050-1200{sup o}C) and sintering time (0-90 min). Density, shrinkage, splitting tensile strength, water absorption and residual loss on ignition (RLOI) were evaluated as measures of sintering efficiency. Scanning electron microscopy (SEM), X-ray microanalysis and X-ray diffraction was used to examine microstructure and phase development due to processing. The results show that premature densification can inhibit complete carbon removal and that carbon combustion is influenced by both internal and external mass transfer conditions. 18 refs., 10 figs., 1 tab.

  14. Alternative sintering methods compared to conventional thermal sintering for inkjet printed silver nanoparticle ink

    NARCIS (Netherlands)

    Niittynen, J.; Abbel, R.; Mäntysalo, M.; Perelaer, J.; Schubert, U.S.; Lupo, D.

    2014-01-01

    In this contribution several alternative sintering methods are compared to traditional thermal sintering as high temperature and long process time of thermal sintering are increasing the costs of inkjet-printing and preventing the use of this technology in large scale manufacturing. Alternative

  15. Neodymium ion diffusion during sintering of Nd : YAG transparent ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hollingsworth, Joel P; Kuntz, Joshua D; Soules, Thomas F [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA, 94550 (United States)

    2009-03-07

    Using an electron microprobe, we measured and characterized the Nd{sup 3+} ion diffusion across a boundary between Nd doped and undoped ceramic yttrium aluminium garnet (YAG) for different temperature ramps and hold times and temperatures. The results show significant Nd ion diffusion on the order of micrometres to tens of micrometres depending on the time and temperature of sintering. The data fit well a model including bulk diffusion, grain boundary diffusion and grain growth. Grain boundary diffusion dominates and grain growth limits grain boundary diffusion by reducing the total cross-sectional area of grain boundaries. (fast track communication)

  16. Effects of sintering temperature on the density and porosity

    African Journals Online (AJOL)

    2013-03-01

    bonding) between the salt beads at all the temperatures in which sintering was performed. .... and the sintering of some covalent solids and low- stability ceramics. The entire sintering process is gen- erally considered to occur in ...

  17. A finite difference model of the iron ore sinter process

    OpenAIRE

    Muller, J.; de Vries, T.L.; Dippenaar, B.A.; Vreugdenburg, J.C.

    2015-01-01

    Iron ore fines are agglomerated to produce sinter, which is an important feed material for blast furnaces worldwide. A model of the iron ore sintering process has been developed with the objective of being representative of the sinter pot test, the standard laboratory process in which the behaviour of specific sinter feed mixtures is evaluated. The model aims to predict sinter quality, including chemical quality and physical strength, as well as key sinter process performance parameters such ...

  18. Liquid phase sintered superconducting cermet

    International Nuclear Information System (INIS)

    Ray, S.P.

    1990-01-01

    This patent describes a method of making a superconducting cermet having superconducting properties with improved bulk density, low porosity and in situ stabilization. It comprises: forming a structure of a superconducting ceramic material having the formula RM 2 Cu 3 O (6.5 + x) wherein R is one or more rare earth elements capable of reacting to form a superconducting ceramic, M is one or more alkaline earth metal elements selected from barium and strontium capable of reacting to form a superconducting ceramic, x is greater than 0 and less than 0.5; and a precious metal compound in solid form selected from the class consisting of oxides, sulfides and halides of silver; and liquid phase sintering the mixture at a temperature wherein the precious metal of the precious metal compound is molten and below the melting point of the ceramic material. The liquid phase sintering is carried out for a time less than 36 hours but sufficient to improve the bulk density of the cermet

  19. Sintered-to-size FBR fuel

    International Nuclear Information System (INIS)

    Rasmussen, D.E.; Schaus, P.S.

    1984-04-01

    Fabrication of sintered-to-size PuO 2 -UO 2 fuel pellets was completed for testing of proposed FBR product specifications. Approximately 6000 pellets were fabricated to two nominal diameters and two densities by cold pressing and sintering to size. Process control and correlation between test and production batches are discussed

  20. Sintering characteristics of nano-ceramic coatings

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Popma, R.

    2003-01-01

    This paper concentrates on sintering characteristics of nano-sized ceramic SiO2 particles. The sintering process is studied as a function of temperature using a conventional furnace and using a laser beam. The underlying idea is to combine the nanoceramic sol-gel concept with inkjet technology and

  1. Thermally stable sintered porous metal articles

    International Nuclear Information System (INIS)

    Gombach, A.L.; Thellmann, E.L.

    1980-01-01

    A sintered porous metal article is provided which is essentially thermally stable at elevated temperatures. In addition, a method for producing such an article is also provided which method comprises preparing a blend of base metal particles and active dispersoid particles, forming the mixture into an article of the desired shape, and heating the so-formed article at sintering temperatures

  2. Sintering of ultra high molecular weight polyethylene

    Indian Academy of Sciences (India)

    Abstract. Ultra high molecular weight polyethylene (UHMWPE) is a high performance polymer having low coefficient of friction, good abrasion resistance, good chemical ... In this study, we report our results on compaction and sintering behaviour of two grades of UHMWPE with reference to the powder morphology, sintering ...

  3. Mechanical characteristics of microwave sintered silicon carbide

    Indian Academy of Sciences (India)

    In firing of products by conventionally sintered process, SiC grain gets oxidized producing SiO2 (∼ 32 wt%) and deteriorates the quality of the product substantially. Partially sintered silicon carbide by such a method is a useful material for a varieties of applications ranging from kiln furniture to membrane material.

  4. Recrystallization and embrittlement of sintered tungsten

    International Nuclear Information System (INIS)

    Bega, N.D.; Babak, A.V.; Uskov, E.I.

    1982-01-01

    The recrystallization of sintered tungsten with a cellular structure of deformation is studied as related to its embrittlement. It is stated that in case of preliminary recrystallization the sintered tungsten crack resistance does not depend on the testing temperature. The tungsten crack resistance is shown to lower with an increase of the structure tendency to primary recrystallization [ru

  5. Master sintering curves of two different alumina powder compacts

    Directory of Open Access Journals (Sweden)

    Vaclav Pouchly

    2009-12-01

    Full Text Available Concept of Master Sintering Curve is a strong tool for optimizing sintering schedule. The sintering behaviour can be predicted, and sintering activation energy can be calculated with the help of few dilatometric measurements. In this paper an automatic procedure was used to calculate Master Sintering Curves of two different alumina compacts. The sintering activation energies were determined as 640 kJ/mol for alumina with particle size of 240 nm, respective 770 kJ/mol for alumina with particle size of 110 nm. The possibility to predict sintering behaviour with the help of Master Sintering Curve was verified.

  6. The Influence of Sintering Temperature of Reactive Sintered (Ti, MoC-Ni Cermets

    Directory of Open Access Journals (Sweden)

    Marek Jõeleht

    2015-09-01

    Full Text Available Titanium-molybdenum carbide nickel cermets ((Ti, MoC-Ni were produced using high energy milling and reactive sintering process. Compared to conventional TiC-NiMo cermet sintering the parameters for reactive sintered cermets vary since additional processes are present such as carbide synthesis. Therefore, it is essential to acquire information about the suitable sintering regime for reactive sintered cermets. One of the key parameters is the final sintering temperature when the liquid binder Ni forms the final matrix and vacancies inside the material are removed. The influence of the final sintering temperature is analyzed by scanning electron microscopy. Mechanical properties of the material are characterized by transverse rupture strength, hardness and fracture toughness.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7179

  7. Two steps sintering alumina doped with niobia

    International Nuclear Information System (INIS)

    Gomes, L.B.; Hatzfeld, J.; Heck, M.; Pokorny, A.; Bergmann, C.P.

    2014-01-01

    In this work, high surface area commercial alumina was doped with niobia and sintered in two steps in order to obtain dense materials with lower processing temperatures. The powders were milled and uniaxially pressed (200 MPa). The first step of sintering took place at 1100°C for 3, 6, 9 and 12 hours, followed by the second step at 1350°C for 3 hours. The relative density, porosity and water absorption of the samples were determined by the Archimedes method. The crystalline phases were analyzed by X-ray Diffraction (XRD) and the morphology of the samples after sintering, evaluated by Scanning Electron Microscopy (SEM). The results indicate that the use of niobia combined with the two steps sintering promotes an increase in the density of the material, even at lower sintering temperatures. (author)

  8. Sintered ceramics having controlled density and porosity

    International Nuclear Information System (INIS)

    Brassfield, H.C.; DeHollander, W.R.; Nivas, Y.

    1980-01-01

    A new method was developed for sintering ceramic uranium dioxide powders, in which ammonium oxalate is admixed with the powder prior to being pressed into a cylindrical green body, so that the end-point density of the final nuclear-reactor fuel product can be controlled. When the green body is heated, the ammonium oxalate decomposes and leaves discrete porosity in the sintered body, which corresponds to the ammonium oxalate regions in the green body. Thus the end-point density of the sintered body is a function of the amount of ammonium oxalate added. The final density of the sintered product is about 90-97% of the theoretical. The addition of ammonium oxalate also allows control of the pore size and distribution throughout the fuel. The process leaves substantially no impurities in the sintered strucuture. (DN)

  9. On the sintering kinetics in UO2

    International Nuclear Information System (INIS)

    Marajofsky, A.

    1998-01-01

    The fabrication process of UO 2 pellets from powders involve pressing and a sintering anneal at high temperature (1650 deg. C to 1750 deg. C) during two or more hours in a hydrogen atmosphere. An alternative method is the oxidative sintering, made at lower temperature (1000 deg. C to 1300 deg. C) in a CO 2 or CO/CO 2 atmosphere. The sintering phenomena consist in the densification of the material by a thermal treatment below the fusion point. For a compact made by pressing a powder, sintering is the process of annulation of the porosity present in the compact or pellet. Several theories describe the sintering phenomena dividing it in three stages, initial, intermediate and final: in all of them the densification is a continuous growing function of time. Nevertheless it has been experimentally reported that a reduction of the density occurs in the third step of the sintering. The phenomena has been called solarization. Solarization has been attributed to the effect of the evolved gases from additives or to the CO 2 atmosphere in oxidative sintering. Thus, it is convenient to distinguish between solarization in oxidative or reducing conditions. Reducing solarization is a consequence of the tendency towards equilibrium of intergranular pores. In oxidative sintering it occurs in the reducing anneal after the sintering and is due to the change in the lattice parameter. This work shows examples of both types of solarization and qualitative interpretation of this phenomena. Both situations show the need of strict control of the sintering and powder production conditions. (author)

  10. Gasification reactivity and ash sintering behaviour of biomass feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Moilanen, A.; Nasrullah, M.

    2011-12-15

    Char gasification reactivity and ash sintering properties of forestry biomass feedstocks selected for large-scale gasification process was characterised. The study was divided into two parts: (1) Internal variation of the reactivity and the ash sintering of feedstocks. (2) Measurement of kinetic parameters of char gasification reactions to be used in the modelling of a gasifier. The tests were carried out in gases relevant to pressurized oxygen gasification, i.e. steam and carbon dioxide, as well as their mixtures with the product gases H{sub 2} and CO. The work was based on experimental measurements using pressurized thermobalance. In the tests, the temperatures were below 1000 deg C, and the pressure range was between 1 and 20 bar. In the first part, it was tested the effect of growing location, storage, plant parts and debarking method. The following biomass types were tested: spruce bark, pine bark, aspen bark, birch bark, forestry residue, bark feedstock mixture, stump chips and hemp. Thick pine bark had the lowest reactivity (instantaneous reaction rate 14%/min) and hemp the highest (250%/min); all other biomasses laid between these values. There was practically no difference in the reactivities among the spruce barks collected from the different locations. For pine bark, the differences were greater, but they were probably due to the thickness of the bark rather than to the growth location. For the spruce barks, the instantaneous reaction rate measured at 90% fuel conversion was 100%/min, for pine barks it varied between 14 and 75%/min. During storage, quite large local differences in reactivity seem to develop. Stump had significantly lower reactivity compared with the others. No clear difference in the reactivity was observed between barks obtained with the wet and dry debarking, but, the sintering of the ash was more enhanced for the bark from dry debarking. Char gasification rate could not be modelled in the gas mixture of H{sub 2}O + CO{sub 2} + H{sub 2

  11. Quantitative analysis for in situ sintering of 3% yttria-stablized zirconia in the transmission electron microscope

    International Nuclear Information System (INIS)

    Majidi, Hasti; Holland, Troy B.; Benthem, Klaus van

    2015-01-01

    Studying particle-agglomerate systems compared to two-particle systems elucidates different stages of sintering by monitoring both pores and particles. We report on in situ sintering of 3% yttria-stablized zirconia particle agglomerates in the transmission electron microscope (TEM). Real-time TEM observations indicate neck formation and growth, particle coalescence and pore closure. A MATLAB-based image processing tool was developed to calculate the projected area of the agglomerate with and without internal pores during in situ sintering. We demonstrate the first densification curves generated from sequentially acquired TEM images. The in situ sintering onset temperature was then determined to be at 960 °C. Densification curves illustrated that the agglomerate projected area which excludes the internal observed pores also shrinks during in situ sintering. To overcome the common projection problem for TEM analyses, agglomerate mass-thickness maps were obtained from low energy-loss analysis combined with STEM imaging. The decrease in the projected area was directly related to the increase in mass-thickness of the agglomerate, likely caused by hidden pores existing in the direction of the beam. Access to shrinkage curves through in situ TEM analysis provides a new avenue to investigate fundamental mechanisms of sintering through directly correlating microstructural changes during consolidation with mesoscale densification behavior

  12. Quantitative analysis for in situ sintering of 3% yttria-stablized zirconia in the transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Majidi, Hasti [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Holland, Troy B. [Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523 (United States); Benthem, Klaus van, E-mail: benthem@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States)

    2015-05-15

    Studying particle-agglomerate systems compared to two-particle systems elucidates different stages of sintering by monitoring both pores and particles. We report on in situ sintering of 3% yttria-stablized zirconia particle agglomerates in the transmission electron microscope (TEM). Real-time TEM observations indicate neck formation and growth, particle coalescence and pore closure. A MATLAB-based image processing tool was developed to calculate the projected area of the agglomerate with and without internal pores during in situ sintering. We demonstrate the first densification curves generated from sequentially acquired TEM images. The in situ sintering onset temperature was then determined to be at 960 °C. Densification curves illustrated that the agglomerate projected area which excludes the internal observed pores also shrinks during in situ sintering. To overcome the common projection problem for TEM analyses, agglomerate mass-thickness maps were obtained from low energy-loss analysis combined with STEM imaging. The decrease in the projected area was directly related to the increase in mass-thickness of the agglomerate, likely caused by hidden pores existing in the direction of the beam. Access to shrinkage curves through in situ TEM analysis provides a new avenue to investigate fundamental mechanisms of sintering through directly correlating microstructural changes during consolidation with mesoscale densification behavior.

  13. Quantitative analysis for in situ sintering of 3% yttria-stablized zirconia in the transmission electron microscope.

    Science.gov (United States)

    Majidi, Hasti; Holland, Troy B; van Benthem, Klaus

    2015-05-01

    Studying particle-agglomerate systems compared to two-particle systems elucidates different stages of sintering by monitoring both pores and particles. We report on in situ sintering of 3% yttria-stablized zirconia particle agglomerates in the transmission electron microscope (TEM). Real-time TEM observations indicate neck formation and growth, particle coalescence and pore closure. A MATLAB-based image processing tool was developed to calculate the projected area of the agglomerate with and without internal pores during in situ sintering. We demonstrate the first densification curves generated from sequentially acquired TEM images. The in situ sintering onset temperature was then determined to be at 960 °C. Densification curves illustrated that the agglomerate projected area which excludes the internal observed pores also shrinks during in situ sintering. To overcome the common projection problem for TEM analyses, agglomerate mass-thickness maps were obtained from low energy-loss analysis combined with STEM imaging. The decrease in the projected area was directly related to the increase in mass-thickness of the agglomerate, likely caused by hidden pores existing in the direction of the beam. Access to shrinkage curves through in situ TEM analysis provides a new avenue to investigate fundamental mechanisms of sintering through directly correlating microstructural changes during consolidation with mesoscale densification behavior. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Titanium Powder Sintering in a Graphite Furnace and Mechanical Properties of Sintered Parts

    Directory of Open Access Journals (Sweden)

    Changzhou Yu

    2017-02-01

    Full Text Available Recent accreditation of titanium powder products for commercial aircraft applications marks a milestone in titanium powder metallurgy. Currently, powder metallurgical titanium production primarily relies on vacuum sintering. This work reported on the feasibility of powder sintering in a non-vacuum furnace and the tensile properties of the as-sintered Ti. Specifically, we investigated atmospheric sintering of commercially pure (C.P. titanium in a graphite furnace backfilled with argon and studied the effects of common contaminants (C, O, N on sintering densification of titanium. It is found that on the surface of the as-sintered titanium, a severely contaminated porous scale was formed and identified as titanium oxycarbonitride. Despite the porous surface, the sintered density in the sample interiors increased with increasing sintering temperature and holding time. Tensile specimens cut from different positions within a large sintered cylinder reveal different tensile properties, strongly dependent on the impurity level mainly carbon and oxygen. Depending on where the specimen is taken from the sintered compact, ultimate tensile strength varied from 300 to 580 MPa. An average tensile elongation of 5% to 7% was observed. Largely depending on the interstitial contents, the fracture modes from typical brittle intergranular fracture to typical ductile fracture.

  15. Sinterability studies on K0.5Na0.5NbO3 using laser as energy source

    International Nuclear Information System (INIS)

    Tian Xiaoyong; Dittmar, Anne; Melcher, Joerg; Heinrich, Juergen G.

    2010-01-01

    The sinterability of K 0.5 Na 0.5 NbO 3 (KNN) ceramics by a laser beam has been investigated in the present research. A 100 W CO 2 laser with a beam diameter of 0.6 mm has been used to sinter the KNN specimens prepared on a uniaxial pressing machine. The relations between laser power and thickness of densified layer, crystallographic structures and phase compositions have been studied. A comparison has been made between laser and furnace sintered KNN samples according to the SEM, XRD and XRF results. The possibility of KNN used for the layer-wise laser direct sintering 3D components has been confirmed in this paper.

  16. Melting and Sintering of Ashes

    DEFF Research Database (Denmark)

    Hansen, Lone Aslaug

    1997-01-01

    -1300°C, and a trend of higher fusion temperatures with increasing contents of Al-silicates and quartz was found.c) Fly ashes, bottom ashes and deposits from coal/straw co-firing were all found to consist mainly of metal-alumina and alumina-silicates. These ashes all melt in the temperature range 1000......The thesis contains an experimental study of the fusion and sintering of ashes collected during straw and coal/straw co-firing.A laboratory technique for quantitative determination of ash fusion has been developed based on Simultaneous Thermal Analysis (STA). By means of this method the fraction......, the biggest deviations being found for salt rich (i.e. straw derived) ashes.A simple model assuming proportionality between fly ash fusion and deposit formation was found to be capable of ranking deposition rates for the different straw derived fly ashes, whereas for the fly ashes from coal/straw co-firing...

  17. Thermodynamics and mechanisms of sintering

    International Nuclear Information System (INIS)

    Pask, J.A.

    1978-10-01

    A phenomenological overview and exploration of the thermodynamic and geometric factors play a role in the process of densification of model compact systems consisting of crystalline spheres of uniform size in regular and irregular packing that form grain boundaries at every contact point. A further assumption is the presence of isotropic surface and grain boundary energies. Although such systems are unrealistic in comparison with normal powder compacts, their potential sintering behavior can be analyzed and provided with a limiting set of behavior conditions which can be looked upon as one boundary condition. This approach is logically realistic since it is easier to understand and provide a basis for understanding the more complex real powder systems

  18. Science of sintering and its future

    International Nuclear Information System (INIS)

    Ristic, M.M.

    1975-01-01

    Some new books published by M.Yu. Baljshin, V.A. Ivensen, V.V. Skorohod and others are characterized by the wish to give a complete approach to the problems of sintering theory. Bearing just this in mind while writing the book ''An Essay on the Generalization of Sintering Theory'' (G.V.Samsonov, M.M. Ristic with the collaborators) an idea was born: to ask the most eminent scientists in this field to present their own opinions on the theme ''The Science of Sintering and Modern Views on its Future''. There were formed 18 questions, given in the appendix to be answered. The received answers were presented in 10 chapters of this book. The fourth part of the book consists of papers of eminent scientists engaged in the field of sintering science (some of which were published here for the first time). This material is published in the book with the consent of the authors and these original contributions provide a more profound knowledge of sintering. The initial idea, that the book should have a monograph character and in which the answers would serve as some data on the latest notions of the science of sintering, was somewhat changed since the original opinions of individual scientists are given in the book and these, are sometimes very contradictory. This, in fact, gives the book a special charm because the unsolved problems in the science of sintering are most evidently stressed in this way

  19. Sintering and microstructure of ice: a review

    International Nuclear Information System (INIS)

    Blackford, Jane R

    2007-01-01

    Sintering of ice is driven by the thermodynamic requirement to decrease surface energy. The structural morphology of ice in nature has many forms-from snowflakes to glaciers. These forms and their evolution depend critically on the balance between the thermodynamic and kinetic factors involved. Ice is a crystalline material so scientific understanding and approaches from more conventional materials can be applied to ice. The early models of solid state ice sintering are based on power law models originally developed in metallurgy. For pressure sintering of ice, these are based on work on hot isostatic pressing of metals and ceramics. Recent advances in recognizing the grain boundary groove geometry between sintering ice particles require models that use new approaches in materials science. The newer models of sintering in materials science are beginning to incorporate more realistic processing conditions and microstructural complexity, and so there is much to be gained from applying these to ice in the future. The vapour pressure of ice is high, which causes it to sublime readily. The main mechanism for isothermal sintering of ice particles is by vapour diffusion; however other transport mechanisms certainly contribute. Plastic deformation with power law creep combined with recrystallization become important mechanisms in sintering with external pressure. Modern experimental techniques, low temperature scanning electron microscopy and x-ray tomography, are providing new insights into the evolution of microstructures in ice. Sintering in the presence of a small volume fraction of the liquid phase causes much higher bond growth rates. This may be important in natural snow which contains impurities that form a liquid phase. Knowledge of ice microstructure and sintering is beneficial in understanding mechanical behaviour in ice friction and the stability of snow slopes prone to avalanches. (topical review)

  20. Experimental sintering of ash at conduit conditions and implications for the longevity of tuffisites

    Science.gov (United States)

    Gardner, James E.; Wadsworth, Fabian B.; Llewellin, Edward W.; Watkins, James M.; Coumans, Jason P.

    2018-03-01

    Escape of gas from magma in the conduit plays a crucial role in mitigating explosivity. Tuffisite veins—ash-filled cracks that form in and around volcanic conduits—represent important gas escape pathways. Sintering of the ash infill decreases its porosity, eventually forming dense glass that is impermeable to gas. We present an experimental investigation of surface tension-driven sintering and associated densification of rhyolitic ash under shallow conduit conditions. Suites of isothermal (700-800 °C) and isobaric H2O pressure (20 and 40 MPa) experiments were run for durations of 5-90 min. Obsidian powders with two different size distributions were used: 1-1600 μm (mean size = 89 μm), and 63-400 μm (mean size = 185 μm). All samples evolved similarly through four textural phases: phase 1—loose and cohesion-less particles; phase 2—particles sintered at contacts and surrounded by fully connected tortuous pore space of up to 40% porosity; phase 3—continuous matrix of partially coalesced particles that contain both isolated spherical vesicles and connected networks of larger, contorted vesicles; phase 4—dense glass with 2-5% fully isolated vesicles that are mainly spherical. Textures evolve faster at higher temperature and higher H2O pressure. Coarse samples sinter more slowly and contain fewer, larger vesicles when fully sintered. We quantify the sintering progress by measuring porosity as a function of experimental run-time, and find an excellent collapse of data when run-time is normalized by the sintering timescale {λ}_s=η \\overline{R}/σ , where η is melt viscosity, \\overline{R} is mean particle radius, and σ is melt-gas surface tension. Because timescales of diffusive H2O equilibration are generally fast compared to those of sintering, the relevant melt viscosity is calculated from the solubility H2O content at experimental temperature and pressure. We use our results to develop a framework for estimating ash sintering rates under shallow

  1. Design of sintering-stable heterogeneous catalysts

    DEFF Research Database (Denmark)

    Gallas-Hulin, Agata

    One of the major issues in the use of metal nanoparticles in heterogeneous catalysis is sintering. Sintering occurs at elevated temperatures because of increased mobility of nanoparticles, leading to their agglomeration and, as a consequence, to the deactivation of the catalyst. It is an emerging...... problem especially for the noble metals-based catalysis. These metals being expensive and scarce, it is worth developing catalyst systems which preserve their activity over time. Encapsulation of nanoparticles inside zeolites is one of the ways to prevent sintering. Entrapment of nanoparticles inside...

  2. Solidification of HLLW into sintered ceramics

    International Nuclear Information System (INIS)

    O-Oka, K.; Ohta, T.; Masuda, S.; Tsunoda, N.

    1979-01-01

    Simulated HLLW from the PNC reprocessing plant at Tokai was solidified into sintered ceramics by normal sintering or hot-pressing with addition of some oxides. Among various ceramic products obtained so far, the most preferable was nepheline-type sintered solids formed with addition of SiO 2 and Al 2 O 3 to the simulated waste calcine. The solid shows advantageous properties in leach rate and mechanical strength, which suggest that the ceramic solids were prepared with additions of ZrO 2 or MnO 2 , and some of them showed good characteristics

  3. Effect of rigid inclusions on sintering

    International Nuclear Information System (INIS)

    Rahaman, M.N.; De Jonghe, L.C.

    1988-01-01

    The predictions of recent theoretical studies on the effect of inert, rigid inclusions on the sintering of ceramic powder matrices are examined and compared with experimental data. The densification of glass matrix composites with inclusion volume fractions of ≤0.15 can be adequately explained by Scherer's theory for viscous sintering with rigid inclusions. Inclusions cause a vast reduction in the densification rates of polycrystalline matrix composites even at low inclusion volume fractions. Models put forward to explain the sintering of polycrystalline matrix composites are discussed

  4. Immobilization of Uranium Silicides in Sintered Glass

    International Nuclear Information System (INIS)

    Mateos, P.; Russo, D.O.; Heredia, A.D.; Sanfilippo, M.

    2003-01-01

    High activity nuclear spent fuels vitrification by fusion is a well known technology which has industrial scale in France, England, Japan, EEUU. Borosilicates glasses are used in this process.Sintered glasses are an alternative to the immobilization task in which there is also a wide experience around the world.The available technics are: cold pressing and sintering , hot-pressing and hot isostatic pressing.This work compares Borosilicates and Iron silicates sintered glasses behaviour when different ammounts of nuclear simulated waste is added

  5. Sintering of nano crystalline o silicon carbide doping with

    Indian Academy of Sciences (India)

    Sinterable silicon carbide powders were prepared by attrition milling and chemical processing of an acheson type -SiC. Pressureless sintering of these powders was achieved by addition of aluminium nitride together with carbon. Nearly 99% sintered density was obtained. The mechanism of sintering was studied by ...

  6. Two-dimensional simulation of sintering process

    International Nuclear Information System (INIS)

    Vasconcelos, Vanderley de; Pinto, Lucio Carlos Martins; Vasconcelos, Wander L.

    1996-01-01

    The results of two-dimensional simulations are directly applied to systems in which one of the dimensions is much smaller than the others, and to sections of three dimensional models. Moreover, these simulations are the first step of the analysis of more complex three-dimensional systems. In this work, two basic features of the sintering process are studied: the types of particle size distributions related to the powder production processes and the evolution of geometric parameters of the resultant microstructures during the solid-state sintering. Random packing of equal spheres is considered in the sintering simulation. The packing algorithm does not take into account the interactive forces between the particles. The used sintering algorithm causes the densification of the particle set. (author)

  7. SINTERED REFRACTORY TUNGSTEN ALLOYS. Gesinterte hochschmelzende wolframlegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Kieffer, R.; Sedlatschek, K.; Braun, H.

    1971-12-15

    Dependence of the melting point of the refractory metals on their positions in the periodic system - alloys of tungsten with other refractory metals - sintering of the alloys - processing of the alloys - technological properties.

  8. U3O8 microspheres sintering kinetics

    International Nuclear Information System (INIS)

    Godoy, A.L.E.

    1986-01-01

    U 3 O 8 microspheres sintering kinetics was determined using a hot-stage optical microscopy apparatus, able to reach temperature up to 1350 0 C in controlled atmospheres. The sintered material had its microstructure analysed by optical and electron microscopy. The microspheres were characterized initialy utilizing X-ray diffractometry and thermogravimetry. The equation which describes the microspheres shrinkage in function of the time was obtained using finite difference analysis X-ray diffractometry indicated hexagonal structure for the microspheres main starting material, ammonium diuranate thermogravimetric analysis showed reduction of this material to U 3 O 8 at 600 0 C. Ceramography results showed 5 hours sintered microspheres grain sizes G vary with the temperature. Sintered U 3 O 8 micrographs compared with published results for UO 2 , indicate similar homogeneity microstructural characteristics and suggest the processed micorspheres to be potentially useful as nuclear fuels. (Author) [pt

  9. Pressureless sintering of whisker-toughened ceramic composites

    Science.gov (United States)

    Tiegs, T.N.

    1993-05-04

    A pressureless sintering method is disclosed for use in the production of whisker-toughened ceramic composites wherein the sintered density of composites containing up to about 20 vol. % SiC whiskers is improved by reducing the average aspect ratio of the whiskers to from about 10 to about 20. Sintering aids further improve the density, permitting the production of composites containing 20 vol. % SiC with sintered densities of 94% or better of theoretical density by a pressureless sintering method.

  10. Mechanical characteristics of microwave sintered silicon carbide

    Indian Academy of Sciences (India)

    Unknown

    sintered process, SiC grain gets oxidized producing SiO2 (∼ 32 wt%) and deteriorates the quality of the product substantially. Partially sintered .... product, could be due to oxidation of SiC, e.g. 50% weight gain of a green SiC sample ... because, the charging current is 90° advanced in phase, ideally, with respect to the ...

  11. Techniques for ceramic sintering using microwave energy

    International Nuclear Information System (INIS)

    Kimrey, H.D.; Janney, M.A.; Becher, P.F.

    1987-01-01

    The use of microwave energy for ceramic sintering offers exciting new possibilities for materials processing. Based on experience gathered in microwave processing associated with the heating of fusion plasmas, we have developed hardware and methods for uniformly heating ceramic parts of large volume and irregular shape to temperatures in excess of 1600 0 C, in vacuum or pressurized atmosphere. Microwave processing at 28 GHz yields enhanced densification rates with a corresponding reduction in sintering temperatures. 6 refs

  12. Terahertz thickness measurements for real industrial applications: from automotive paints to aerospace industry (Conference Presentation)

    Science.gov (United States)

    Krimi, Soufiene; Beigang, René

    2017-02-01

    In this contribution, we present a highly accurate approach for real-time thickness measurements of multilayered coatings using terahertz time domain spectroscopy in reflection geometry. The proposed approach combines the benefits of a model-based material parameters extraction method to calibrate the specimen under test, a generalized modeling method to simulate the terahertz radiation behavior within arbitrary thin films, and the robustness of a powerful evolutionary optimization algorithm to increase the sensitivity and the precision of the minimum thickness measurement limit. Furthermore, a novel self-calibration model is introduced, which takes into consideration the real industrial challenges such as the effect of wet-on-wet spray in the car painting process and the influence of the spraying conditions and the sintering process on ceramic thermal barrier coatings (TBCs) in aircraft industry. In addition, the developed approach enables for some applications the simultaneous determination of the complex refractive index and the coating thickness. Hence, a pre-calibration of the specimen under test is not required for such cases. Due to the high robustness of the self-calibration method and the genetic optimization algorithms, the approach has been successfully applied to resolve individual layer thicknesses within multi-layered coated samples down to less than 10 µm. The regression method can be applied in time-domain, frequency-domain or in both the time and frequency-domain simultaneously. The data evaluation uses general-purpose computing on graphics processing units and thanks to the developed highly parallelized algorithm lasts less than 300 ms. Thus, industrial requirements for fast thickness measurements with an "every-second-cycle" can be fulfilled.

  13. Spark Plasma Sintering of Ultracapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Curtis W. [CK Technologies, Camirillo, CA (United States); Boatner, Lynn A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Tucker, Dennis [NASA Johnson Space Center, Houston, TX (United States); Kolopus, James A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cheng, Zhongyang [Auburn Univ., AL (United States)

    2016-01-01

    A solid-state ultracapacitor module to replace standard electrochemical batteries would achieve major performance gains and mass/volume reduction. This report summarizes a project to evaluate an alternative sintering process to produce a solid-state ultracapacitor to overcome the limitations of both the electrochemical batteries presently in use on spacecraft and of currently available electrochemical ultracapacitors. It will provide a robust energy storage device with higher reliability, wider working temperature range, longer lifetime, and less weight and volume than electrochemical batteries. As modern electronics decrease in size, more efficient and robust remote power is needed. Current state-of-the-art rechargeable batteries cannot be rapidly charged, contain harmful chemicals, and suffer from early wear-out mechanisms. Solid-state ultracapacitors are recyclable energy storage devices that offer the promise of higher power and a greater number of charge/discharge cycles than current rechargeable batteries. In addition, the theoretical energy density when compared to current electrochemical batteries indicates that a significant weight savings is possible. This is a project to develop a very high density solid-state ultracapacitor with giant permittivity and acceptable dielectric loss to overcome the energy-density barrier such that it will be a suitable replacement for batteries.

  14. Structural, optical and gas sensing properties of screen-printed nanostructured Sr-doped SnO2 thick film sensor

    International Nuclear Information System (INIS)

    Shaikh, F.I.; Chikhale, L.P.; Patil, J.Y.; Rajgure, A.V.; Suryavanshi, S.S.; Mulla, I.S.

    2013-01-01

    The nanocrystalline materials of strontium doped tin oxide powders were synthesized by conventional co-precipitation method. Synthesized nanophase SnO 2 powders were used to fabricate thick films of pure and Sr-doped SnO 2 using screen-printing technology and investigated for their gas sensing properties towards LPG, ethanol, ammonia and acetone vapor. The crystal structure and phase of the sintered powders were characterized by X-ray diffractometer (XRD) and microstructure by scanning electron microscopy (SEM). All the doped and undoped SnO 2 compositions revealed single phase and solid solution formation. X-ray diffractometer (XRD) results indicated that well crystallized Sr-doped SnO 2 particles of size about 10 nm were obtained at sintering temperature 700℃. The optical properties viz. UV-Vis, FTIR and Raman were used to characterize various physico-chemical properties of samples. The reduction of grain size in metal oxide is a key factor to enhance the gas sensing properties. The doping of Sr in SnO 2 has reduced the grain size and improved the gas response. The results of gas sensing measurements showed that the thick films deposited on alumina substrates using screen-printing technique exhibited high gas response, quick response time and fast recovery time to acetone gas at a working temperature of 250℃. Further, the selectivity of sensor towards acetone with respect to other reducing gases (LPG, ethanol, ammonia) was studied. (author)

  15. A study on some properties of sintered stainless steel powder compacts with sintering conditions

    International Nuclear Information System (INIS)

    Lee, Bang Sik; Kim, Kwan Hyu; Lee, Doh Jae; Choi, Dap Chun

    1986-01-01

    Sintered specimens for the mechanical and corrosion tests were prepared from 316L, 410L and 434L stainless steel powder compacts with green densities in the range of 6.2∼7.0g/cm 3 . The experimental variables studied were green density, sintering atmosphere, temperature and time, type of lubricant used and cooling rate after sintering operation. Mechanical properties of green compacts and sintered specimens were evaluated. The corrosion tests were performed by potentiodynamic anodic polarization technique. Mechanical properties were very sensitive to the sintering atmosphere; sintering in dissociated ammonia resulted in the strengthing but embrittlement of sintered 316L, 410L and 434L strainless steel powder compacts. Their corrosion resistance was also decreased. The tensile strength was increased with increases in sintering time and temperature while the decreases in the yield strength were observed. The tensile properties of green compacts were shown to closely related to the green density. Addition of 1% acrawax as a lubricant was appeared to be most effective for the improvement of green strength. (Author)

  16. Grain growth in uranium nitride prepared by spark plasma sintering

    Science.gov (United States)

    Johnson, Kyle D.; Lopes, Denise Adorno

    2018-05-01

    Uranium mononitride (UN) has long been considered a potential high density, high performance fuel candidate for light water reactor (LWR) and fast reactor (FR) applications. However, deployability of this fuel has been limited by the notable resistance to sintering and subsequent difficulty in producing a desirable microstructure, the high costs associated with 15N enrichment, as well as the known proclivity to oxidation and interaction with steam. In this study, the stimulation of grain growth in UN pellets sintered using SPS has been investigated. The results reveal that by using SPS and controlling temperature, time, and holding pressure, grain growth can be stimulated and controlled to produce a material featuring both a desired porosity and grain size, at least within the range of interest for nuclear fuel candidates. Grain sizes up to 31 μm were obtained using temperatures of 1650 °C and hold times of 15 min. Evaluation by EBSD reveal grain rotation and coalescence as the dominant mechanism in grain growth, which is suppressed by the application of higher external pressure. Moreover, complete closure of the porosity of the material was observed at relative densities of 96% TD, resulting in a material with sufficient porosity to accommodate LWR burnup. These results indicate that a method exists for the economic fabrication of an 15N-bearing uranium mononitride fuel with favorable microstructural characteristics compatible with use in a light water-cooled nuclear reactor.

  17. Solid-state sintering of tungsten heavy alloys

    International Nuclear Information System (INIS)

    Gurwell, W.E.

    1994-10-01

    Solid-state sintering is a technologically important step in the fabrication of tungsten heavy alloys. This work addresses practical variables affecting the sinterability: powder particle size, powder mixing, and sintering temperature and time. Compositions containing 1 to 10 micrometer (μM) tungsten (W) powders can be fully densified at temperatures near the matrix solidus. Blending with an intensifier bar provided good dispersion of elemental powders and good as-sintered mechanical properties under adequate sintering conditions. Additional ball milling increases powder bulk density which primarily benefits mold and die filling. Although fine, 1 μm W powder blends have high sinterability, higher as-sintered ductilities are reached in shorter sintering times with coarser, 5 μm W powder blends; 10μm W powder blends promise the highest as-sintered ductilities due to their coarse microstructural W

  18. Discrimination symbol applying method for sintered nuclear fuel product

    International Nuclear Information System (INIS)

    Ishizaki, Jin

    1998-01-01

    The present invention provides a symbol applying method for applying discrimination information such as an enrichment degree on the end face of a sintered nuclear product. Namely, discrimination symbols of information of powders are applied by a sintering aid to the end face of a molded member formed by molding nuclear fuel powders under pressure. Then, the molded product is sintered. The sintering aid comprises aluminum oxide, a mixture of aluminum oxide and silicon dioxide, aluminum hydride or aluminum stearate alone or in admixture. As an applying means of the sintering aid, discrimination symbols of information of powders are drawn by an isostearic acid on the end face of the molded product, and the sintering aid is sprayed thereto, or the sintering aid is applied directly, or the sintering aid is suspended in isostearic acid, and the suspension is applied with a brush. As a result, visible discrimination information can be applied to the sintered member easily. (N.H.)

  19. Analysis of key factors influencing the evaporation performances of an oriented linear cutting copper fiber sintered felt

    Science.gov (United States)

    Pan, Minqiang; Zhong, Yujian

    2018-01-01

    Porous structure can effectively enhance the heat transfer efficiency. A kind of micro vaporizer using the oriented linear cutting copper fiber sintered felt is proposed in this work. Multiple long cutting copper fibers are firstly fabricated with a multi-tooth tool and then sintered together in parallel to form uniform thickness metal fiber sintered felts that provided a characteristic of oriented microchannels. The temperature rise response and thermal conversion efficiency are experimentally investigated to evaluate the influences of porosity, surface structure, feed flow rate and input power on the evaporation characteristics. It is indicated that the temperature rise response of water is mainly affected by input power and feed flow rate. High input power and low feed flow rate present better temperature rise response of water. Porosity rather than surface structure plays an important role in the temperature rise response of water at a relatively high input power. The thermal conversion efficiency is dominated by the input power and surface structure. The oriented linear cutting copper fiber sintered felts for three kinds of porosities show better thermal conversion efficiency than that of the oriented linear copper wire sintered felt when the input power is less than 115 W. All the sintered felts have almost the same performance of thermal conversion at a high input power.

  20. Laser sintering of metal powders on top of sintered layers under multiple-line laser scanning

    International Nuclear Information System (INIS)

    Xiao Bin; Zhang Yuwen

    2007-01-01

    A three-dimensional numerical model for multiple-line sintering of loose powders on top of multiple sintered layers under the irradiation of a moving Gaussian laser beam is carried out. The overlaps between vertically deposited layers and adjacent lines which strengthen bonding are taken into account. The energy equation is formulated using the temperature transforming model and solved by the finite volume method. The effects of the number of the existing sintered layers, porosity and initial temperature coupled with the optimal combination laser intensity and scanning velocity are presented. The results show that the liquid pool moves slightly towards the negative scanning direction and the shape of the liquid pool becomes shallower with higher scanning velocity. A higher laser intensity is needed to achieve the required overlaps when the number of the existing sintered layers increases. Increasing porosity or initial temperature enhances the sintering process and thus less intensity is needed for the overlap requirement

  1. Comparison of the target-thickness dependence of the convoy electron yield and the Rydberg electron yield measured in coincidence with exit charge states in fast ion-solid collisions

    International Nuclear Information System (INIS)

    Gaither, C.C. III; Breinig, M.; Freyou, J.; Underwood, T.A.

    1988-01-01

    We have simultaneously measured the yield of convoy electrons and the yield of electrons in high Rydberg states of the projectile (n /approx gt/ 70), produced by 2MeV/u C projectiles passing through C foils, whose thicknesses range from 4--10 ug/cm 2 , for incident charge states q/sub i/ = 4--6 and exit charge states q/sub e/ = 4--6. We have found that these yields exhibit similar trends as a function of foil thickness, but that, nevertheless, the ratio of the number of convoy electrons detected in coincidence with ions of exit charge state q/sub e/ to the number of electrons detected in high Rydberg states of ions with the same exit charge state is a function of foil thickness. This may be due to a broadening of the convoy electron energy spectrum with increasing foil thickness. 6 refs., 3 figs

  2. Progress in Dual (Piezoelectric-Magnetostrictive Phase Magnetoelectric Sintered Composites

    Directory of Open Access Journals (Sweden)

    Rashed Adnan Islam

    2012-01-01

    Full Text Available The primary aims of this review article are (a to develop the fundamental understanding of ME behavior in perovskite piezoelectric-spinel magnetostrictive composite systems, (b to identify the role of composition, microstructural variables, phase transformations, composite geometry, and postsintering heat treatment on ME coefficient, and (c to synthesize, characterize, and utilize the high ME coefficient composite. The desired range of ME coefficient in the sintered composite is 0.5–1 V/cm⋅Oe. The studies showed that the soft piezoelectric phase quantified by smaller elastic modulus, large grain size of piezoelectric phase (~1 μm, and layered structures yields higher magnitude of ME coefficient. It is also found that postsintering thermal treatment such as annealing and aging alters the magnitude of magnetization providing an increase in the magnitude of ME coefficient. A trilayer composite was synthesized using pressure-assisted sintering with soft phase [0.9 PZT–0.1 PZN] having grain size larger than 1 μm and soft ferromagnetic phase of composition Ni0.8Cu0.2Zn0.2Fe2O4 [NCZF]. The composite showed a high ME coefficient of 412 and 494 mV/cm⋅Oe after sintering and annealing, respectively. Optimized ferrite to PZT thickness ratio was found to be 5.33, providing ME coefficient of 525 mV/cm⋅Oe. The ME coefficient exhibited orientation dependence with respect to applied magnetic field. Multilayering the PZT layer increased the magnitude of ME coefficient to 782 mV/cm⋅Oe. Piezoelectric grain texturing and nanoparticulate assembly techniques were incorporated with the layered geometry. It was found that with moderate texturing, d33 and ME coefficient reached up to 325 pC/N and 878 mV/cm⋅Oe, respectively. Nanoparticulate core shell assembly shows the promise for achieving large ME coefficient in the sintered composites. A systematic relationship between composition, microstructure, geometry, and properties is

  3. Effects of sintering atmosphere and initial particle size on sintering of gadolinia-doped ceria

    International Nuclear Information System (INIS)

    Batista, Rafael Morgado

    2014-01-01

    The effects of the sintering atmosphere and initial particle size on the sintering of ceria containing 10 mol% gadolinia (GdO 1.5 ) were systematically investigated. The main physical parameter was the specific surface area of the initial powders. Nanometric powders with three different specific surface areas were utilized, 210 m 2 /g, 36,2 m 2 /g e 7,4 m 2 /g. The influence on the densification, and micro structural evolution were evaluated. The starting sintering temperature was verified to decrease with increasing on the specific surface area of raw powders. The densification was accelerated for the materials with smaller particle size. Sintering paths for crystallite growth were obtained. Master sintering curves for gadolinium-doped ceria were constructed for all initial powders. A computational program was developed for this purpose. The results for apparent activation energy showed noticeable dependence with specific surface area. In this work, the apparent activation energy for densification increased with the initial particle size of powders. The evolution of the particle size distributions on non isothermal sintering was investigated by WPPM method. It was verified that the grain growth controlling mechanism on gadolinia doped ceria is the pore drag for initial stage and beginning of intermediate stage. The effects of the sintering atmosphere on the stoichiometry deviation of ceria, densification, microstructure evolution, and electrical conductivity were analyzed. Inert, oxidizing, and reducing atmospheres were utilized on this work. Deviations on ceria stoichiometry were verified on the bulk materials. The deviation verified was dependent of the specific surface area and sintering atmosphere. Higher reduction potential atmospheres increase Ce 3+ bulk concentration after sintering. Accelerated grain growth and lower electrical conductivities were verified when reduction reactions are significantly present on sintering. (author)

  4. Electric-Loading Enhanced Kinetics in Oxide Ceramics: Pore Migration, Sintering and Grain Growth: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chen, I-Wei [Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Materials Science & Engineering

    2018-02-02

    Solid oxide fuel cells and solid oxide electrolysis cells rely on solid electrolytes in which a large ionic current dominates. This project was initiated to investigate microstructural changes in such devices under electrochemical forces, because nominally insignificant processes may couple to the large ionic current to yield non-equilibrium phenomena that alter the microstructure. Our studies had focused on yttria-stabilized cubic zirconia (YSZ) widely used in these devices. The experiments have revealed enhanced grain growth at higher temperatures, pore and gas bubble migration at all temperatures, and the latter also lead to enhanced sintering of highly porous ceramics into fully dense ceramics at unprecedentedly low temperatures. These results have shed light on kinetic processes that fall completely outside the realm of classical ceramic processing. Other fast-oxygen oxide ceramics closely related to, and often used in conjunction with zirconia ceramics, have also be investigated, as are closely related scientific problems in zirconia ceramics. These include crystal structures, defects, diffusion kinetics, oxygen potentials, low temperature sintering, flash sintering, and coarsening theory, and all have resulted in greater clarity in scientific understanding. The knowledge is leveraged to provide new insight to electrode kinetics and near-electrode mixed conductivity and to new materials. In the following areas, our research has resulted in completely new knowledge that defines the state-of-the-art of the field. (a) Electrical current driven non-equilibrium phenomena, (b) Enhanced grain growth under electrochemically reducing conditions, (c) Development of oxygen potential polarization in electrically loaded electrolyte, (d) Low temperature sintering and grain growth, and (e) Structure, defects and cation kinetics of fluorite-structured oxides. Our research has also contributed to synthesis of new energy-relevant electrochemical materials and new understanding

  5. Master sintering curve: A practical approach to its construction

    Directory of Open Access Journals (Sweden)

    Pouchly V.

    2010-01-01

    Full Text Available The concept of a Master Sintering Curve (MSC is a strong tool for optimizing the sintering process. However, constructing the MSC from sintering data involves complicated and time-consuming calculations. A practical method for the construction of a MSC is presented in the paper. With the help of a few dilatometric sintering experiments the newly developed software calculates the MSC and finds the optimal activation energy of a given material. The software, which also enables sintering prediction, was verified by sintering tetragonal and cubic zirconia, and alumina of two different particle sizes.

  6. Water cooling system for sintering furnaces of nuclear fuel pellets

    International Nuclear Information System (INIS)

    1996-01-01

    This work has as a main objective to develop a continuous cooling water system, which is necessary for the cooling of the sintering furnaces. This system is used to protect them as well as for reducing the water consumption, ejecting the heat generated into this furnaces and scattering it into the atmosphere in a fast and continuous way. The problem was defined and the reference parameters established, making the adequate research. The materials were selected as well as the length of the pipeline which will carry the secondary refrigerant fluid (water). Three possible solutions were tried,and evaluated, and from these, the thermal and economically most efficient option was selected. The layout of the solution was established and the theoretical construction of a cooling system for liquids using dichlorofluoromethane (R-22), as a refrigerant and a air cooled condenser, was accomplished. (Author)

  7. Integrated analysis of oxide nuclear fuel sintering

    International Nuclear Information System (INIS)

    Baranov, V.; Kuzmin, R.; Tenishev, A.; Timoshin, I.; Khlunov, A.; Ivanov, A.; Petrov, I.

    2011-01-01

    Dilatometric and thermal-gravimetric investigations have been carried out for the sintering process of oxide nuclear fuel in gaseous Ar - 8% H 2 atmosphere at temperatures up to 1600 0 C. The pressed compacts were fabricated under real production conditions of the OAO MSZ with application of two different technologies, so called 'dry' and 'wet' technologies. Effects of the grain size growth after the heating to different temperatures were observed. In order to investigate the effects produced by rate of heating on properties of sintered fuel pellets, the heating rates were varied from 1 to 8 0 C per minute. Time of isothermal overexposure at maximal temperature (1600 0 C) was about 8 hours. Real production conditions were imitated. The results showed that the sintering process of the fuel pellets produced by two technologies differs. The samples sintered under different heating rates were studied with application of scanning electronic microscopy analysis for determination of mean grain size. A simulation of heating profile for industrial furnaces was performed to reduce the beam cycles and estimate the effects of variation of the isothermal overexposure temperatures. Based on this data, an optimization of the sintering conditions was performed in operations terms of OAO MSZ. (authors)

  8. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.C.

    1975-01-01

    A process is described for preparing novel sintered cobalt--rare earth intermetallic products which can be magnetized to form permanent magnets having stable improved magnetic properties. A cobalt--rare earth metal alloy is formed having a composition which at sintering temperature falls outside the composition covered by the single Co 5 R intermetallic phase on the rare earth richer side. The alloy contains a major amount of the Co 5 R intermetallic phase and a second solid CoR phase which is richer in rare earth metal content than the Co 5 R phase. The specific cobalt and rare earth metal content of the alloy is substantially the same as that desired in the sintered product. The alloy, in particulate form, is pressed into compacts and sintered to the desired density. The sintered product is comprised of a major amount of the Co 5 R solid intermetallic phase and up to about 35 percent of the product of the second solid CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase

  9. Study of Thermal Fatigue Resistance of a Composite Coating Made by a Vacuum Fusion Sintering Method

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Thermal fatigue behavior of a Ni-base alloy chromium carbide composite coating made by a vacuum fusion sintering method are discussed. Results show that thermal fatigue behavior is associated with cyclic upper temperature and coating thickness. As the thickness of the coating decreases, the thermal fatigue resistance increases. The thermal fatigue resistance cuts down with the thermal cyclic upper temperature rising. The crack growth rate decreases with the increase in cyclic number until crack arrests. Thermal fatigue failure was not found along the interface of the coating/matrix. The tract of thermal fatigue crack cracks along the interfaces of phases.

  10. New materials through a variety of sintering methods

    Science.gov (United States)

    Jaworska, L.; Cyboroń, J.; Cygan, S.; Laszkiewicz-Łukasik, J.; Podsiadło, M.; Novak, P.; Holovenko, Y.

    2018-03-01

    New sintering techniques make it possible to obtain materials with special properties that are impossible to obtain by conventional sintering techniques. This issue is especially important for ceramic materials for application under extreme conditions. Following the tendency to limit critical materials in manufacturing processes, the use of W, Si, B, Co, Cr should be limited, also. One of the cheapest and widely available materials is aluminum oxide, which shows differences in phase composition, grain size, hardness, strain and fracture toughness of the same type of powder, sintered via various methods. In this paper the alumina was sintered using the conventional free sintering process, microwave sintering, Spark Plasma Sintering (SPS), high pressure-high temperature method (HP-HT) and High Pressure Spark Plasma Sintering (HP SPS). Phase composition analysis, by X-ray diffraction of the alumina materials sintered using various methods, was carried out. For the conventional sintering method, compacts are composed of α-Al2O3 and θ-Al2O3. For compacts sintered using SPS, microwave and HP-HT methods, χ-Al2O3 and γ-Al2O3 phases were additionally present. Mechanical and physical properties of the obtained materials were compared between the methods of sintering. On the basis of images from scanning electron microscope quantitative analysis was performed to determine the degree of grain growth of alumina after sintering.

  11. Influence of sintering temperature on mechanical properties of spark plasma sintered pre-alloyed Ti-6Al-4 V powder

    Energy Technology Data Exchange (ETDEWEB)

    Muthuchamy, A.; Patel, Paridh; Rajadurai, M. [VIT Univ., Vellore, Tamil Nadu (India); Chaurisiya, Jitendar K. [NIT, Suratkal (India); Annamalai, A. Raja [VIT Univ., Vellore, Tamil Nadu (India). Centre for Innovative Manufacturing Research

    2018-04-01

    Spark plasma sintering provides faster heating that can create fully, or near fully, dense samples without significant grain growth. In this study, pre-alloyed Ti-6Al-4 V powder compact samples produced through field assisted sintering in a spark plasma sintering machine are compared as a function of consolidation temperature. The effect of sintering temperature on the densification mechanism, microstructural evolution and mechanical properties of spark plasma sintered Ti-6Al-4 V alloy compacts was investigated in detail. The compact, sintered at 1100 C, exhibited near net density, highest hardness and strength as compared to the other compacts processed at a temperature lower than 1100 C.

  12. Sintering method for nuclear fuel pellet

    International Nuclear Information System (INIS)

    Omuta, Hirofumi; Nakabayashi, Shigetoshi.

    1997-01-01

    When sintering a compressed nuclear fuel powder in an atmosphere of a mixed gas comprising hydrogen and nitrogen, steams are added to the mixed gas to suppress the nitrogen content in sintered nuclear fuel pellets. In addition, the content of nitrogen impurities in the nuclear fuel pellets can be controlled by controlling the amount of steams to be added to the mixed gas, namely, by controlling the dew point as an index thereof. If the addition amount of steams to the mixed gas is determined by controlling the dew point as an index, the content of nitrogen impurities in the sintered nuclear fuel pellets can be controlled reliably to a specified value of 0.0075% or less. If ammonolyzed gas is used as the mixed gas, a more economical mixed gas can be obtained than in the case of forming mixed gas by mixing the hydrogen gas and the nitrogen gas. (N.H.)

  13. Electro sinter forging of titanium disks

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Chris Valentin; Bay, Niels Oluf

    by measuring the electrical resistance during the sintering process [5], since low electrical resistance corresponds to high density. It is, however, necessary to be aware that increased temperature, on the other hand, increases the resistance. SEM micrographs and Computed Tomography (CT) are carried out......Electro sinter forging (ESF) is a new sintering process based on the principle of electrical Joule heating. In the present work, middle frequency direct current (MFDC) was flowing through the powder compact, which was under mechanical pressure. The main parameters are the high electrical current......, up to 10 kA, and the low voltage, 1-2 V, resulting in heat generation in the powder. Figure 1 shows the experimental setup. The punches were made of a conductive material; namely a copper alloy. The die, which has to be electrically insulating, was made of alumina. The ESF process takes 3-4s...

  14. Sintered cobalt-rare earth intermetallic product

    International Nuclear Information System (INIS)

    Benz, M.G.

    1975-01-01

    This patent describes a sintered product having substantially stable permanent magnet properties in air at room temperature. It comprises compacted particulate cobalt--rare earth alloy consisting essentially of a Co 5 R intermetallic phase and a CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase, where R is a rare earth metal. The Co 5 R intermetallic phase is present in an amount of at least 65 percent by weight of the sintered product and the CoR intermetallic phase which is richer in rare earth metal content than the Co 5 R phase is present in a positive amount having a value ranging up to about 35 percent by weight of the product. The sintered product has a density of at least 87 percent and has pores which are substantially noninterconnecting and wherein the component grains have an average size less than 30 microns

  15. Method of manufacturing sintered nuclear fuel

    International Nuclear Information System (INIS)

    Watarumi, Kazutoshi.

    1984-01-01

    Purpose: To obtain composite pellets with an improved strength. Method: A core mainly composed of fuel materials is previously prepared, embedded into the central portion of a pellet, silted therearound with cladding material, and then pressmolded and sintered. For instance, a rugby-ball like core body with the maximum outer diameter of 6 mm and the height of 6 mm is made by compressive molding with uranium dioxide powder, then coating material comprising the same powder incorporated with 0.1 % by weight of SiC fibers is filled around the core body, which is molded into a composite pellet by means of pressing and then sintered at 1600 0 C, to obtain a sintered pellet of 93.5 % theoretical density. As the result of the compression test for the pellet, it showed a strength greater by 15 % than that of the similar mono-layer pellet. (Kamimura, M.)

  16. Combustion of fuels with low sintering temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dalin, D

    1950-08-16

    A furnace for the combustion of low sintering temperature fuel consists of a vertical fuel shaft arranged to be charged from above and supplied with combustion air from below and containing a system of tube coils extending through the fuel bed and serving the circulation of a heat-absorbing fluid, such as water or steam. The tube-coil system has portions of different heat-absorbing capacity which are so related to the intensity of combustion in the zones of the fuel shaft in which they are located as to keep all parts of the fuel charge below sintering temperature.

  17. Fusibility and sintering characteristics of ash

    Energy Technology Data Exchange (ETDEWEB)

    Ots, A. A., E-mail: aots@sti.ttu.ee [Tallinn University of Technology (Estonia)

    2012-03-15

    The temperature characteristics of ash fusibility are studied for a wide range of bituminous and brown coals, lignites, and shales with ratios R{sub B/A} of their alkaline and acid components between 0.03 and 4. Acritical value of R{sub B/A} is found at which the fusion temperatures are minimal. The sintering properties of the ashes are determined by measuring the force required to fracture a cylindrical sample. It is found that the strength of the samples increases sharply at certain temperatures. The alkali metal content of the ashes has a strong effect on their sintering characteristics.

  18. Non-contact assessment of electrical performance for rapidly sintered nanoparticle silver coatings through colorimetry

    International Nuclear Information System (INIS)

    Cherrington, M.; Claypole, T.C.; Gethin, D.T.; Worsley, D.A.; Deganello, D.

    2012-01-01

    The color change during the ultrafast near-infrared sintering process of a nanoparticle silver ink has been correlated to its electrical performance through colorimetry using the CIELAB industry standard. Nanoparticle silver ink films, deposited over a flexible polyethylene terephthalate substrate, presented significant shifting in the a* and b* color coordinates during sintering, exhibiting the best conductivity with an a* coordinate of approximately 0 and a b* coordinate of approximately + 10. This color change has been associated with the Lorenz–Mie theory of electromagnetic scattering. This indirect measurement technique is potentially a breakthrough technology for fast in-line non-contact characterization of the drying and sintering process of nanoparticle conductive inks for use in large area roll-to-roll processing of printed electronics. - Highlights: ► Color change of a nanoparticle silver coating was measured during sintering ► Color change was correlated to the electrical performance of the coating. ► Potential in-line non-contact measurement method for roll-to-roll printed electronics

  19. Non-contact assessment of electrical performance for rapidly sintered nanoparticle silver coatings through colorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Cherrington, M.; Claypole, T.C.; Gethin, D.T. [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom); Worsley, D.A. [SPECIFIC, College of Engineering, Swansea University, Baglan Bay Innovation Centre, Central Avenue, Baglan Energy Park, Port Talbot, SA12 7AX (United Kingdom); Deganello, D., E-mail: d.deganello@swansea.ac.uk [Welsh Centre for Printing and Coating, College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP (United Kingdom)

    2012-11-01

    The color change during the ultrafast near-infrared sintering process of a nanoparticle silver ink has been correlated to its electrical performance through colorimetry using the CIELAB industry standard. Nanoparticle silver ink films, deposited over a flexible polyethylene terephthalate substrate, presented significant shifting in the a* and b* color coordinates during sintering, exhibiting the best conductivity with an a* coordinate of approximately 0 and a b* coordinate of approximately + 10. This color change has been associated with the Lorenz-Mie theory of electromagnetic scattering. This indirect measurement technique is potentially a breakthrough technology for fast in-line non-contact characterization of the drying and sintering process of nanoparticle conductive inks for use in large area roll-to-roll processing of printed electronics. - Highlights: Black-Right-Pointing-Pointer Color change of a nanoparticle silver coating was measured during sintering Black-Right-Pointing-Pointer Color change was correlated to the electrical performance of the coating. Black-Right-Pointing-Pointer Potential in-line non-contact measurement method for roll-to-roll printed electronics.

  20. Current state of the Uranium dioxide sintering theory

    International Nuclear Information System (INIS)

    Baranov, V.; Devyatko, Y.; Tenishev, A.; Khlunov, A.; Khomyakov, O.

    2011-01-01

    The basic approaches to the description of the ceramics sintering phenomenon are considered. It is established that diffusive sintering models incorrectly describe an intermediate stage of this process. The physical model of sintering, considering the substance plastic flow of pressing under the influence of internal stress forces and capillary forces, as the basic mechanism defining the shrinkage of sintering oxide nuclear fuel, is offered. (authors)

  1. Peculiarities of formation and sintering of fine dispersed molybdenum powders

    International Nuclear Information System (INIS)

    Kalamazov, R.U.; Pak, V.I.; Tsvetkov, Yu.V.; Lem, I.N.

    1989-01-01

    Pressing of fine dispersed Mo powders sintering of compacts in H 2 and vacuum is studied. It is shown that powder preannealing at 600 deg C in H 2 for 2 hours is necessary for formation of dense sintered compacts. Qualitatively choice of pressing conditions is possible when using electron-positron annihilation method. Peculiarities of compacting and sintering of fine- and coarse-dispersed powder mixtures are considered. The obtained results are discussed from the view point of sintering recrystallization mechanism

  2. Sintering of dioxide pellets in an oxidizing atmosphere (CO2)

    International Nuclear Information System (INIS)

    Santos, G.R.T.

    1992-01-01

    This work consists in the study of the sintering process of U O 2 pellets in an oxidizing atmosphere. Sintering tests were performed in an CO 2 atmosphere and the influence of temperature and time on the pellets density and microstructure were verified. The results obtained were compared to those from the conventional sintering process and its efficiency was confirmed. (author)

  3. Improving NASICON Sinterability through Crystallization under High Frequency Electrical Fields

    Directory of Open Access Journals (Sweden)

    Ilya eLisenker

    2016-03-01

    Full Text Available The effect of high frequency (HF electric fields on the crystallization and sintering rates of a lithium aluminum germanium phosphate (LAGP ion conducting ceramic was investigated. LAGP with the nominal composition Li1.5Al0.5Ge1.5(PO43 was crystallized and sintered, both conventionally and under effect of electrical field. Electrical field application, of 300V/cm at 1MHz, produced up to a 40% improvement in sintering rate of LAGP that was crystallized and sintered under the HF field. Heat sink effect of the electrodes appears to arrest thermal runaway and subsequent flash behavior. Sintered pellets were characterized using XRD, SEM, TEM and EIS to compare conventionally and field sintered processes. The as-sintered structure appears largely unaffected by the field as the sintering curves tend to converge beyond initial stages of sintering. Differences in densities and microstructure after 1 hour of sintering were minor with measured sintering strains of 31% vs. 26% with and without field, respectively . Ionic conductivity of the sintered pellets was evaluated and no deterioration due to the use of HF field was noted, though capacitance of grain boundaries due to secondary phases was significantly increased.

  4. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    Wang, G.P.; Liu, W.Q.; Huang, Y.L.; Ma, S.C.; Zhong, Z.C.

    2014-01-01

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively

  5. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.P., E-mail: wgp@jxnu.edu.cn [College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022 (China); Liu, W.Q. [Key Laboratory of Advanced Functional Materials Science and Engineering, Ministry of Education, Beijing University of Technology, Beijing 100022 (China); Huang, Y.L.; Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2014-01-15

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively.

  6. Blast furnace sinter performance improvement; Melhoria do rendimento de sinter de alto forno

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Ricardo Baeta; Ferreira, Antonio Marcos M.; Perez, Jose Antonio; Nobrega, Carlos A.; Madeira Filho, Nelson Santos; Silva, Jose Coutinho da; Sampaio, Silvio; Larcher, Marcos A.; Silva Filho, Jose Maximo da; Nogueira, Carlos Alberto; Ramalho Filho, Wilson; Costa, Jose Luiz Lage da; Silva, Mauro Correa da [Companhia Siderurgica de Tubarao (CST), Serra, ES (Brazil)

    1995-07-01

    The article discusses the following issues of methodology maid and the accomplished actions aiming at the blast furnace sinter performance improvement: performance concept; performance historical evolution; problem boarding; influence factors; interpretation of the results; actions implementation; and economic benefit.

  7. Sintering behavior of LZSA glass-ceramics

    Directory of Open Access Journals (Sweden)

    Oscar Rubem Klegues Montedo

    2009-06-01

    Full Text Available The LZSA glass-ceramic system (Li2O-ZrO2-SiO2-Al2O 3 shows interesting properties, such as good chemical resistance, low thermal expansion, high abrasion resistance, and a low dielectric constant. However, in order to obtain a high performance material for specific applications, the sintering behavior must be better understood so that the porosity may be reduced and other properties improved. In this context, a sintering investigation for a specific LZSA glass-ceramic system composition was carried out. A 18.8Li2O-8.3ZrO2-64.2SiO2-8.7Al 2O3 glass was prepared by melting the solids, quenching the melt in water, and grinding the resulting solid in order to obtain a powder (3.68 μm average particle diameter. Subsequently, the glass powder was characterized (chemical analysis and determination of thermal properties and the sintering behavior was investigated using optical non-contact dilatometry measurements. The results showed that the crystallization process strongly reduced the sintering in the temperature interval from 785 to 940 °C, and a maximum thermal shrinkage of 15.4% was obtained with operating conditions of 1020 °C and 180 minutes.

  8. Study of ceramics sintering under high pressures

    International Nuclear Information System (INIS)

    Kunrath Neto, A.O.

    1990-01-01

    A systematic study was made on high pressure sintering of ceramics in order to obtain materials with controlled microstructure, which are not accessible by conventional methods. Some aspects with particular interest were: to achieve very low porosity, with fine grains; to produce dispersed metastable and denser phases which can act as toughening agents; the study of new possibilities for toughening enhancement. (author)

  9. Low temperature sintering of hyperstoichiometric uranium dioxide

    International Nuclear Information System (INIS)

    Chevrel, H.

    1991-12-01

    In the lattice of uranium dioxide with hyperstoichiometric oxygen content (UO 2+x ), each additional oxygen atoms is introduced by shifting two anions from normal sites to interstitial ones, thereby creating two oxygen vacancies. The point defects then combine to form complex defects comprising several interstitials and vacancies. The group of anions (3x) in the interstitial position participate in equilibria promoting the creation of uranium vacancies thereby considerably increasing uranium self-diffusion. However, uranium grain boundaries diffusion governs densification during the first two stages of sintering of uranium dioxide with hyperstoichiometric oxygen content, i.e., up to 93% of the theoretical density. Surface diffusion and evaporation-condensation, which are considerably accentuated by the hyperstoichiometric deviation, play an active role during sintering by promoting crystalline growth during the second and third stages of sintering. U 8 O 8 can be added to adjust the stoichiometry and to form a finely porous structure and thus increase the pore area subjected to surface phenomena. The composition with an O/U ratio equal to 2.25 is found to densify the best, despite a linear growth in sintering activation energy with hyperstoichiometric oxygen content, increasing from 300 kj.mol -1 for UO 2.10 to 440 kJ.mol -1 for UO 2.25 . Seeds can be introduced to obtain original microstructures, for example the presence of large grains in small-grain matrix

  10. Deformation behavior of sintered nanocrystalline silver layers

    International Nuclear Information System (INIS)

    Zabihzadeh, S.; Van Petegem, S.; Duarte, L.I.; Mokso, R.; Cervellino, A.; Van Swygenhoven, H.

    2015-01-01

    The microstructure of porous silver layers produced under different low temperature pressure-assisted sintering conditions is characterized and linked with the mechanical behavior studied in situ during X-ray diffraction. Peak profile analysis reveals important strain recovery and hardening mechanism during cyclic deformation. The competition between both mechanisms is discussed in terms of porosity and grain size

  11. Sintering of magnesia: effect of additives

    Indian Academy of Sciences (India)

    Effect of different additives, namely Cr2O3, Fe2O3 and TiO2, up to 2 wt% was studied on the sinter- ing and .... mental distribution of the components is shown in figure 7. It shows ... Chiang Y M, Birniand D and Kingery W 1996 Physical ceram-.

  12. Laser Sintering Technology and Balling Phenomenon.

    Science.gov (United States)

    Oyar, Perihan

    2018-02-01

    The aim of this review was to evaluate the balling phenomenon which occurs typically in Selective Laser Sintering (SLS). The balling phenomenon is a typical SLS defect, and observed in laser sintered powder, significantly reduces the quality of SLS, and hinders the further development of SLS Technology. Electronic database searches were performed using Google Scholar. The keywords "laser sintering, selective laser sintering, direct metal laser melting, and balling phenomenon" were searched in title/abstract of publications, limited to December 31, 2016. The inclusion criteria were SLS, balling phenomenon, some alloys (such as Cr-Co, iron, stainless steel, and Cu-based alloys) mechanical properties, microstructure and bond strength between metal-ceramic crown, laboratory studies, full text, and in English language. A total of 100 articles were found the initial search and yielded a total of 50 studies, 30 of which did not fulfill the inclusion criteria and were therefore excluded. In addition, 20 studies were found by screening the reference list of all included publications. Finally, 40 studies were selected for this review. The method in question is regulated by powder material characteristics and the conditions of laser processing. The procedure of formation, affecting factors, and the mechanism of the balling effect are very complex.

  13. Reduction of surface erosion caused by helium blistering in sintered beryllium and sintered aluminum powder

    International Nuclear Information System (INIS)

    Das, S.K.; Kaminsky, M.

    1976-01-01

    Studies have been conducted to find materials with microstructures which minimize the formation of blisters. A promising class of materials appears to be sintered metal powder with small average grain sizes and low atomic number Z. Studies of the surface erosion of sintered aluminum powder (SAP 895) and of aluminum held at 400 0 C due to blistering by 100 keV helium ions have been conducted and the results are compared to those obtained earlier for room temperature irradiation. A significant reduction of the erosion rate in SAP 895 in comparison to annealed aluminum and SAP 930 is observed. In addition results on the blistering of sintered beryllium powder (type I) irradiated at room temperature and 600 0 C by 100 keV helium ions are given. These results will be compared with those reported recently for vacuum cast beryllium foil and a foil of sintered beryllium powder (type II) which was fabricated differently, than type I. For room temperature irradiation only a few blisters could be observed in sintered beryllium powder type I and type II and they are smaller in size and in number than in vacuum cast beryllium. For irradiation at 600 0 C large scale exfoliation of blisters was observed for vacuum cast beryllium but much less exfoliation was seen for sintered beryllium powder, type I, and type II. The results show a reduction in erosion rate cast beryllium, for both room temperature and 600 0 C

  14. Sintering uranium oxide using a preheating step

    International Nuclear Information System (INIS)

    Jensen, N.J.; Nivas, Y.; Packard, D.R.

    1977-01-01

    Compacted pellets of uranium oxide or uranium oxide with one or more additives are heated in a kiln in a process having a preheating step, a sintering step, a reduction step, and a cooling step in a controlled atmosphere. The process is practiced to give a range of temperature and atmosphere conditions for obtaining optimum fluoride removal from the compacted pellets along with optimum sintering in a single process. The preheating step of this process is conducted in a temperature range of about 600 0 to about 900 0 C and the pellets are held for at least twenty min, and preferably about 60 min, in an atmosphere having a composition in the range of about 10 to about 75 vol % hydrogen with the balance being carbon dioxide. The sintering step is conducted at a temperature in the range of about 900 0 C to 1500 0 C in the presence of an atmosphere having a composition in the range of about 0.5 to about 90 vol % hydrogen with the balance being carbon dioxide. The reduction step reduces the oxygen to metal ratio of the pellets to a range of about 1.98 to 2.10:1 and this is accomplished by gradually cooling the pellets for about 30 to about 120 min from the temperature of the sintering step to about 1100 0 C in an atmosphere of about 10 to 90 vol % hydrogen with the balance being carbon dioxide. Thereafter the pellets are cooled to about 100 0 C under a protective atmosphere, and in one preferred practice the same atmosphere used in the reduction step is used in the cooling step. The preheating, sintering and reduction steps may also be conducted with their respective atmospheres having an initial additional component of water vapor and the water vapor can comprise up to about 20 vol %

  15. Characterization of plasma nitrided layers produced on sintered iron

    Directory of Open Access Journals (Sweden)

    Marcos Alves Fontes

    2014-07-01

    Full Text Available Plasma nitriding is a thermo-physical-chemical treatment process, which promotes surface hardening, caused by interstitial diffusion of atomic nitrogen into metallic alloys. In this work, this process was employed in the surface modification of a sintered ferrous alloy. Scanning electron microscopy (SEM, X-ray diffraction (XRD analyses, and wear and microhardness tests were performed on the samples submitted to ferrox treatment and plasma nitriding carried out under different conditions of time and temperature. The results showed that the nitride layer thickness is higher for all nitrided samples than for ferrox treated samples, and this layer thickness increases with nitriding time and temperature, and temperature is a more significant variable. The XRD analysis showed that the nitrided layer, for all samples, near the surface consists in a mixture of γ′-Fe4N and ɛ-Fe3N phases. Both wear resistance and microhardness increase with nitriding time and temperature, and temperature influences both the characteristics the most.

  16. The quantitative characterization of sintering of urania powders

    International Nuclear Information System (INIS)

    Das, P.; Kulkarni, U.D.

    1981-01-01

    This paper presents a unified approach towards characterization of the sintering behaviour of UO 2 powders in terms of their extrinsic properties. Empirical equations connecting the sintering index with various powder parameters have been set up. The influence of various powder parameters, either individually or as dimensionless/dimensional groups, on the sintering behaviour has been studied. The relative importance of these factors has also been analysed. A good polynomial fit has been obtained for variation of sintering index with some of the powder parameters and dimensionless/dimensional groups. The equations are expected to provide a good basis for assessing the sinterability of UO 2 powders. (Auth.)

  17. Comparative sinterability of combustion synthesized and commercial titanium carbides

    International Nuclear Information System (INIS)

    Manley, B.W.

    1984-11-01

    The influence of various parameters on the sinterability of combustion synthesized titanium carbide was investigaged. Titanium carbide powders, prepared by the combustion synthesis process, were sintered in the temperature range 1150 to 1600 0 C. Incomplete combustion and high oxygen contents were found to be the cause of reduced shrinkage during sintering of the combustion syntheized powders when compared to the shrinkage of commercial TiC. Free carbon was shown to inhibit shrinkage. The activation energy for sintering was found to depend on stoichiometry (C/Ti). With decreasing C/Ti, the rate of sintering increased. 29 references, 16 figures, 13 tables

  18. Enhancement of pool boiling heat transfer in water using sintered copper microporous coatings

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Seong Chul; KIm, Jin Sub; You, Seung M. [Dept. of Mechanical Engineering, The University of Texas at Dallas, Richardson (United States); Son, Dong Gun; KIm, Hwan Yeol [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-08-15

    Pool boiling heat transfer of water saturated at atmospheric pressure was investigated experimentally on Cu surfaces with high-temperature, thermally-conductive, microporous coatings (HTCMC). The coatings were created by sintering Cu powders on Cu surfaces in a nitrogen gas environment. A parametric study of the effects of particle size and coating thickness was conducted using three average particle sizes (APSs) of 10 μm, 25 μm, and 67 μm and various coating thicknesses. It was found that nucleate boiling heat transfer (NBHT) and critical heat flux (CHF) were enhanced significantly for sintered microporous coatings. This is believed to have resulted from the random porous structures that appear to include reentrant type cavities. The maximum NBHT coefficient was measured to be approximately 400 kW/m2k with APS 67 μm and 296 μm coating thicknesses. This value is approximately eight times higher than that of a plain Cu surface. The maximum CHF observed was 2.1 MW/m2 at APS 67 μm and 428 μm coating thicknesses, which is approximately double the CHF of a plain Cu surface. The enhancement of NBHT and CHF appeared to increase as the particle size increased in the tested range. However, two larger particle sizes (25 μm and 67 μm) showed a similar level of enhancement.

  19. Fast reactor programme

    International Nuclear Information System (INIS)

    Hoekstra, E.K.

    1976-11-01

    Estimated reactivity effects of fission products in the SNR-300 fast breeder are given. Neutron cross sections of 127 I and 129 I are also given. Results of the in-pile canning failure experiments on fuel pins R54-F35 and F39 are discussed. Sinter experiments using mixed UC-UN powders are reported. Results of tensile tests on high-dose and low-dose irradiated specimens of 18Cr1 1Ni stainless steel (DIN 1.4948) used in the SNR-300 reactor vessel are given. It is shown that the aerosol behaviour in condensing sodium vapour can be described by the same MADCA model developed for the decay of aerosols in condensing water vapour. Results of heat transfer measurements in the electrically heated 28-rod bundle under liquid-phase and subsequently under two-phase conditions are commented on

  20. Influence of sintering necks on the spectral behaviour of ITO clusters using the Discrete Dipole Approximation

    International Nuclear Information System (INIS)

    Skorupski, Krzysztof; Hellmers, Jens; Feng, Wen; Mroczka, Janusz; Wriedt, Thomas; Mädler, Lutz

    2015-01-01

    In this paper we study the spectral behaviour of indium tin oxide (ITO) nanoparticle clusters using different sinter neck models for the connections between the primary particles. The investigations include light scattering calculations based on the Discrete Dipole Approximation (DDA). The corresponding clusters are generated using the Cluster–Cluster algorithm proposed by Filippov et al. Different sintering neck models led to significantly different spectral features. A spectral neck factor that reveals the thickness of the necks connecting the primary particles with a simple measurement method is introduced. - Highlights: • We investigate the necking phenomenon in ITO fractal-like aggregates. • Extinction diagrams are sensitive to changes of the neck size. • We propose a simple procedure for measuring the neck size in ITO aggregates

  1. Development of sintered composites CaSO4 doped with Dy and Nd

    International Nuclear Information System (INIS)

    Chagas, M.A.P.; Parente, L.J.; Souza, D.N.

    2007-01-01

    The main of this work was the developing of sintered composites in order to use as thermoluminescent dosimeters using a simple route to preparation, employing high temperature. The composites were prepared with CaSO 4 .2H 2 O doped with Dy 2 O 3 and NdO 3 . Initially CaSO 4 .2H 2 O was dehydrated in oven at 100 deg C by 1h. After the addiction dopants and homogenization of compounds, PVA was incorporated to make easy to compaction of composites. The pellets with 6 mm of diameter and 1 mm thickness were sintered at 900 deg C and 1000 deg C by 6 h. The TL emission showed two peaks when the samples were irradiated with beta source (Sr 90 +Y 90 ). In all cases, the calibration curves presented responses proportional to absorbed dose. The results showed that this material have potential to be used in dosimetry. (author)

  2. Studies on the sintering of copper powder compacts

    International Nuclear Information System (INIS)

    Elmasry, M.A.A.; Abadir, M.F.; Mahdy, A.N.; Elkinawy, W.S.

    1995-01-01

    Solid state sintering behavior of cylindrical compacts, (1 cm diameter and 1 cm height), made of copper powder was studied within a range of compacting pressure of 75 up to 300 MPa, sintering temperature of 600 up to to 900 degree C, and sintering time of 5 up to 60 min in a reducing atmosphere composed of H2 and N 2 gases with a volumetric ratio 3:1. The green and the sintered densities were found to to increase with the compacting pressure. Higher sintering temperature, and time favour increased sintered density. probable mechanisms during the initial stage of sintering were disclosed. It was found that low pressures cause dilation of closed pores, and vice versa. At low pressures and temperatures the surface diffusion mechanism is favoured, While high temperatures favour lattice diffusion mechanism. at high pressures, the lattice diffusion mechanism is suppressed while surface diffusion predominates. Density and hence shrinkage were also found to increase with the increase of sintering time, While its rate increases with the increase of sintering temperature. the influence of sintering conditions on the hardness of the compacts was studied. An increase in hardness, When higher compacting pressures and higher sintering temperatures were adopted, has bee obtained. 11 figs

  3. Factors Affecting the Sintering of UO2 Pellets

    International Nuclear Information System (INIS)

    El-Hakim, E.; Afifi, Y.K.

    1999-01-01

    Sintering of UO 2 pellets is affected by many parameters such as; UO 2 powder parameters, the conditions followed for preparing the green UO 2 pellets and the sintering scheme(heating and cooling rate, soaking time and temperature). The aim of this work is to study the effect of some these parameters on the characteristics of the sintered UO 2 pellets were qualified according to the technical specifications of Candu fuel. Pressed green pellets at different pressing force (15 to 50 k N) were sintered at 1650 ±20 degree for two hours to study the effect of pressing force on the sintered pellets characteristics; visual inspection, pellet dimensions, density and shrinkage ratio. Compacted green pellets at a pressing force of 48 k N were sintered at different sintering temperature (1600± 20 degree, 1650 ±20 degree, 1700± 20 degree) for two hours to study the effect of sintering temperature on the sintered pellets characteristics. The effect of the heating rate (200,300 and 400 degree per hour) on the sintered pellets characteristics was also investigated. It was found that the pressing force used to compact the green pellets had an effect on the density of the sintered pellets. Pellets pressed at 15 k N have a density of 10.3 g/cm 3 while, those pressed at 50 k N have a density of 10.6 g/cm 3. It was observed that increasing the heating rate to 400 degree /h lead to cracked pellets

  4. Inversion defects in MgAl2O4 elaborated by pressureless sintering, pressureless sintering plus hot isostatic pressing, and spark plasma sintering

    International Nuclear Information System (INIS)

    Mussi, A.; Granger, G. Bernard; Addad, A.; Benameur, N.; Beclin, F.; Bataille, A.

    2009-01-01

    The distribution of inversion defects of Al was investigated in dense magnesium-aluminate spinel elaborated by pressureless sintering, pressureless sintering plus hot isostatic pressing, and spark plasma sintering. This study was conducted by energy electron loss spectroscopy analyses and more particularly by energy loss near edge structure investigations of the Al-L 2,3 edge. Several aspects are discussed with the purpose of understanding why charged defects dispersal reveals a special configuration.

  5. Sintering studies on iron-carbon-copper compacts

    Directory of Open Access Journals (Sweden)

    Perianayagam Philomen-D-Anand Raj

    2016-01-01

    Full Text Available Sintered Iron-Carbon-Copper parts are among the most widely used powder metallurgy product in automobile. In this paper, studies have been carried out to find out the sintering characteristics of iron-carbon-copper compacts when sintered in nitrogen atmosphere. The effects of various processing parameters on the sintering characteristics were studied. The various processing parameters considered were compaction pressure, green density and sintering temperature. The sintering characteristics determined were sintered density, porosity, dimensional change, micro hardness and radial crush strength. The results obtained have been discussed on the basis of micro structural observations. The characteristics of SEM fractography were also used to determine the mechanism of fracture. The fracture energy is strongly dependent on density of the compact.

  6. Gas response properties of citrate gel synthesized nanocrystalline MgFe2O4: Effect of sintering temperature

    International Nuclear Information System (INIS)

    Patil, J.Y.; Mulla, I.S.; Suryavanshi, S.S.

    2013-01-01

    Graphical abstract: Display Omitted Highlights: ► Synthesis of nanocrystalline MgFe 2 O 4 by economical citrate gel combustion method. ► Structural, morphological, and gas response properties of MgFe 2 O 4 . ► Enhancement in selectivity of MgFe 2 O 4 towards LPG with sintering temperature. ► Use of MgFe 2 O 4 to detect different gases at different operating temperatures. -- Abstract: Spinel type MgFe 2 O 4 material was synthesized by citrate gel combustion method. The effect of sintering temperature on structural, morphological, and gas response properties was studied. The powder X-ray diffraction pattern and transmission electron microscope study confirms nanocrystalline spinel structure of the synthesized powder. The material was tested for response properties to various reducing gases like liquid petroleum gas (LPG), acetone, ethanol, and ammonia. The results demonstrated n-type semiconducting behavior of MgFe 2 O 4 material. It was revealed that MgFe 2 O 4 sintered at 973 K was most sensitive to LPG at 648 K and to acetone at 498 K. However MgFe 2 O 4 sintered at 1173 K exhibited higher response and selectivity to LPG with marginal increase in the operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. It was observed that the particles size, porosity, and surface activity of the sensor material is affected by the sintering temperature.

  7. The observation of resistivity change on the ultrasonic treated Fe-Cr ODS sinter alloy under magnetic field influence

    Science.gov (United States)

    Silalahi, Marzuki; Purwanto, Setyo; Mujamilah; Dimyati, Arbi

    2018-03-01

    About the observation of resistivity change on the ultrasonic treated Fe-Cr ODS sinter alloy under magnetic field influence. This paper reported about the observation of the resistivity change in the ultrasonic pre-treated Fe-Cr ODS sinter alloy under the influence of magnetic field at the Center for Science and Technology of Advanced Material, Nuclear Energy Agency of Indonesia. Fe-Cr ODS alloy were sinthesized by vacuum sintering of Fe- and Cr-powder dispersed Y2O3. However, before sintering the powder mixture was subjected to the irradiation process by ultrasonic for 50 hours at 20 kHz and then isostatic pressed up to 50.91 MPa to form a coin of 10 mm in diameter. LCR meassurement revealed the decreasing of resistivity about 3 times by increasing of applied magnetic field from 0 to 70 mT. In addition, VSM meassurement was performed on both as powder material and as sintered sample. The results showed increasing the magnetization with increasing magnetic field and the curve exhibits almost exact symmetry S-form with small hysterese indicating fast changing magnetization and demagnetization capability without energy loss. This opens strong speculations about the existence of magnetoresistant property of the material which is important for many application in field of sensors or electro magnetic valves.

  8. Reaction sintering of ceramic-metal composites

    International Nuclear Information System (INIS)

    Botta Filho, W.J.; Rodrigues, J.A.; Tomasi, R.; Pandolfelli, V.C.; Passos, J.F.S.S.; Folgueras, M.V.

    1990-01-01

    Reaction sintering experiments have been carried out in the system Al 2 O 3 -ZrAl 2 -Nb 2 O 5 with the objective of producing ceramic-metal composites of improved toughness. The sintering treatments have been done in the temperature range of 700 0 C to 1400 0 C under different conditions of vacuum and in air and argon atmospheres. The treated samples have been analysed by X-ray diffraction and analytical electron microscopy. The results are discussed in function of the degree of reaction, the development of microstructure and the densification. These results have shown that although an exchange reaction can occur to produce a composite, the control of the reaction to obtain a dense microstructure has not been possible yet. (author) [pt

  9. Production of sintered porous metal fluoride pellets

    Science.gov (United States)

    Anderson, L.W.; Stephenson, M.J.

    1973-12-25

    Porous pellets characterized by a moderately reactive crust and a softer core of higher reactivity are produced by forming agglomerates containing a metal fluoride powder and a selected amount ofwater. The metal fluoride is selected to be sinterable and essentially non-reactive with gaseous fluorinating agents. The agglomerates are contacted with a gaseous fluorinating agent under controlled conditions whereby the heat generated by localized reaction of the agent and water is limited to values effccting bonding by localized sintering. Porous pellets composed of cryolite (Na/sub 3/AlF/sub 6/) can be used to selectively remove trace quantities of niobium pentafluoride from a feed gas consisting predominantly of uranium hexafluoride. (Official Gazette)

  10. Foaming Glass Using High Pressure Sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    Foam glass is a high added value product which contributes to waste recycling and energy efficiency through heat insulation. The foaming can be initiated by a chemical or physical process. Chemical foaming with aid of a foaming agent is the dominant industrial process. Physical foaming has two...... to expand. After heat-treatment foam glass can be obtained with porosities of 80–90 %. In this study we conduct physical foaming of cathode ray tube (CRT) panel glass by sintering under high pressure (5-25 MPa) using helium, nitrogen, or argon at 640 °C (~108 Pa s). Reheating a sample in a heating...... variations. One way is by saturation of glass melts with gas. The other involves sintering of powdered glass under a high gas pressure resulting in glass pellets with high pressure bubbles entrapped. Reheating the glass pellets above the glass transition temperature under ambient pressure allows the bubbles...

  11. The dimensional accuracy of the sintered billets

    Directory of Open Access Journals (Sweden)

    Чингиз Ариф оглы Алиев

    2016-01-01

    Full Text Available The article presents the results of assessing the impact of the behaviour stability of the components included in the compositions and process parameters of their production, on the dimensional accuracy of workpieces. It was found that by increasing the amount of oxide in the composition is greater compaction of the sintered billet in the process of heat treatment. This also increases the density of all components of the composition

  12. Spark plasma sintering of tantalum carbide

    International Nuclear Information System (INIS)

    Khaleghi, Evan; Lin, Yen-Shan; Meyers, Marc A.; Olevsky, Eugene A.

    2010-01-01

    A tantalum carbide powder was consolidated by spark plasma sintering. The specimens were processed under various temperature and pressure conditions and characterized in terms of relative density, grain size, rupture strength and hardness. The results are compared to hot pressing conducted under similar settings. It is shown that high densification is accompanied by substantial grain growth. Carbon nanotubes were added to mitigate grain growth; however, while increasing specimens' rupture strength and final density, they had little effect on grain growth.

  13. Electrical properties of thick-layer piezo resistors based on Bi2Ru2O7

    International Nuclear Information System (INIS)

    Golonka, L.; Tankiewicz, S.

    1997-01-01

    Piezoelectric effect and electrical properties of thick-layer resistors based on Bi 2 Ru 2 O 7 (on ceramic substrate) have been studied. The influence of selected technological parameters (sintering temperature, chemical composition, heat treatment) on system properties has been estimated. 4 refs, 7 figs

  14. Microstructural Studies of Ni-P Thick Film Resistor Temperature Sensors

    Directory of Open Access Journals (Sweden)

    Barbara Holodnik

    1986-01-01

    Full Text Available Thick Ni-P films have been widely investigated at our Institute. This article tends to visualize by use of various microscopic methods how the growth and sintering of individual conducting grains, results in the formation of nickel dendrites responsible for the metallic character of electrical conduction.

  15. Thermoelectric Coolers with Sintered Silver Interconnects

    Science.gov (United States)

    Kähler, Julian; Stranz, Andrej; Waag, Andreas; Peiner, Erwin

    2014-06-01

    The fabrication and performance of a sintered Peltier cooler (SPC) based on bismuth telluride with sintered silver interconnects are described. Miniature SPC modules with a footprint of 20 mm2 were assembled using pick-and-place pressure-assisted silver sintering at low pressure (5.5 N/mm2) and moderate temperature (250°C to 270°C). A modified flip-chip bonder combined with screen/stencil printing for paste transfer was used for the pick-and-place process, enabling high positioning accuracy, easy handling of the tiny bismuth telluride pellets, and immediate visual process control. A specific contact resistance of (1.4 ± 0.1) × 10-5 Ω cm2 was found, which is in the range of values reported for high-temperature solder interconnects of bismuth telluride pellets. The realized SPCs were evaluated from room temperature to 300°C, considerably outperforming the operating temperature range of standard commercial Peltier coolers. Temperature cycling capability was investigated from 100°C to 235°C over more than 200 h, i.e., 850 cycles, during which no degradation of module resistance or cooling performance occurred.

  16. Sintered stabilized zirconia microstructure and conductivity

    International Nuclear Information System (INIS)

    Bernard, Herve.

    1981-04-01

    The elaboration of a stabilized zirconia powder which sinters at 1300 0 C and the influence of the sintered polycristal microstructure on its ionic conductivity have been studied. Among three investigated powder preparation processes, coprecipitation in an ammoniacal solution was chosen. After sintering at 1300 0 C, the pellet density was higher than 93% of the theoretical density. It even approached up to 98% TD with addition of less than 0,5 mole % Al 2 O 3 to the initial powder. The overall electrolyte conductivity and the inter and intragranular contributions have been determined by complex impedance spectroscopy. ZrO 2 -Y 2 O 3 solid solution conductivity was scarcely improved by Y 2 O 3 exchange with Yb 2 O 3 or Gd 2 O 3 . This conductivity greatly increases with grain size, its improvement with decreasing porosity, which has been quantified, is less sensible. Moreover, two original properties were noticed: small amounts of Al 2 O 3 and quenching greatly enhanced the overall conductivity. At temperatures below 500 0 C, grain boundaries only insured a partial migration of conductive ions. A parallel type electrical equivalent circuit suited well with this blocking effect [fr

  17. Gammatography of thick lead vessels

    International Nuclear Information System (INIS)

    Raghunath, V.M.; Bhatnagar, P.K.; Sundaram, V.M.

    1979-01-01

    Radiography, scintillation and GM counting and dose measurements using ionisation chamber equipment are commonly used for detecting flaws/voids in materials. The first method is mostly used for steel vessels and to a lesser extent thin lead vessels also and is essentially qualitative. Dose measuring techniques are used for very thick and large lead vessels for which high strength radioactive sources are required, with its inherent handling problems. For vessels of intermediate thicknesses, it is ideal to use a small strength source and a GM or scintillation counter assembly. At the Reactor Research Centre, Kalpakkam, such a system was used for checking three lead vessels of thicknesses varying from 38mm to 65mm. The tolerances specified were +- 4% variation in lead thickness. The measurements also revealed the non concentricity of one vessel which had a thickness varying from 38mm to 44mm. The second vessel was patently non-concentric and the dimensional variation was truly reproduced in the measurements. A third vessel was fabricated with careful control of dimensions and the measurements exhibited good concentricity. Small deviations were observed, attributable to imperfect bondings between steel and lead. This technique has the following advantages: (a) weaker sources used result in less handling problems reducing the personnel exposures considerably; (b) the sensitivity of the instrument is quite good because of better statistics; (c) the time required for scanning a small vessel is more, but a judicious use of a scintillometer for initial fast scan will help in reducing the total scanning time; (d) this method can take advantage of the dimensional variations themselves to get the calibration and to estimate the deviations from specified tolerances. (auth.)

  18. Analysis of the conductivity of commercial easy sintering grade 3 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} materials

    Energy Technology Data Exchange (ETDEWEB)

    Badwal, Sukhvinder P.S.; Ciacchi, Fabio T.; Giampietro, Kristine M. [CSIRO, Manufacturing and Infrastructure Technology, Private Bag 33, Clayton South 3169, Victoria (Australia)

    2005-01-14

    Fine grain zirconia-yttria materials are required for enhanced performance in solid oxide fuel cells and related devices and in applications requiring good thermo-mechanical properties. Materials with about 3 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} composition are good electrolyte materials for solid oxide fuel cell, ceramic membrane oxygen separation and a number of related devices because of their superior mechanical properties and ease of fabrication into thin self-supporting structures in comparison with a material in the 8-10 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} composition range. In this study, sintering behaviour, impedance studies, four-probe DC conductivity measurements and microstructure analysis has been performed on various easy sintering grade materials from two commercial powder suppliers. These materials achieve near theoretical density at sintering temperatures as low as 1350-1400C. For direct comparison of the conductivity and impedance behaviour in easy sintering grade materials, several other 3 mol% Y{sub 2}O{sub 3}-ZrO{sub 2} powders were also investigated. The total ionic conductivity at 850C in easy sintering grade materials is comparable with normal-grade commercial materials of similar composition despite a slightly higher grain boundary impedance at lower temperatures (below circa 450C). There were no obvious differences in the grain boundary thickness, calculated from the impedance data, of normal and easy sintering grade materials.

  19. Characterization of the porous structures of the green body and sintered biomedical titanium scaffolds with micro-computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Arifvianto, B., E-mail: b.arifvianto@tudelft.nl; Leeflang, M.A.; Zhou, J.

    2016-11-15

    The present research was aimed at gaining an understanding of the porous structure changes from the green body through water leaching and sintering to titanium scaffolds. Micro-computed tomography (micro-CT) was performed to generate 3D models of titanium scaffold preforms containing carbamide space-holding particles and sintered scaffolds containing macro- and micro-pores. The porosity values and structural parameters were determined by means of image analysis. The result showed that the porosity values, macro-pore sizes, connectivity densities and specific surface areas of the titanium scaffolds sintered at 1200 °C for 3 h did not significantly deviate from those of the green structures with various volume fractions of the space holder. Titanium scaffolds with a maximum specific surface area could be produced with an addition of 60–65 vol% carbamide particles to the matrix powder. The connectivity of pores inside the scaffold increased with rising volume fraction of the space holder. The shrinkage of the scaffolds prepared with > 50 vol% carbamide space holder, occurring during sintering, was caused by the reductions of macro-pore sizes and micro-pore sizes as well as the thickness of struts. In conclusion, the final porous structural characteristics of titanium scaffolds could be estimated from those of the green body. - Highlights: •Porous structures of green body and sintered titanium scaffolds was studied. •Porous structures of both samples were quantitatively characterized with micro-CT. •Porous structures of scaffolds could be controlled from the green body. •Shrinkage mechanisms of titanium scaffolds during sintering was established.

  20. Microwave sintering of nano size powder β-TCP bioceramics

    Directory of Open Access Journals (Sweden)

    Mirhadi B.

    2014-01-01

    Full Text Available A nano sized beta tricalcium phosphate (β-TCP powder was conventional sintered (CS and microwave sintered (MW, in order to obtain dense β-TCP ceramics. In this work the effect of microwave sintering conditions on the microstructure, phase composition and mechanical properties of materials based on tricalcium phosphate (TCP was investigated by SEM (scanning electron microscopyand XRD(X-ray diffraction and then compared with conventional sintered samples. Nano-size β-TCP powders with average grain size of 80 nm were prepared by the wet chemical precipitation method with calcium nitrate and diammonium hydrogen phosphate as calcium and phosphorus precursors, respectively. The precipitation process employed was also found to be suitable for the production of submicrometre β-TCP powder in situ. The β-TCP samples microwave (MW sintered for 15 min at 1100°C, with average grain size of 3μm, showed better densification, higher density and certainly higher hardness than samples conventionally sintered for 2 h at the same temperature. By comparing sintered and MW sintered β-TCP samples, it was concluded that MW sintered β-TCP samples have superior mechanical properties.

  1. Microwave sintering of zirconia toughened alumina at 28GHz

    International Nuclear Information System (INIS)

    Samandi, M.; Ji, H.; Miyake, S.

    1998-01-01

    Microwave radiation from a 10 kW, CW gyrotron operating at 28 GHz was employed to sinter 10% zirconia toughened alumina (ZTA) ceramic samples. It has been established that the use of millimetre wave radiation circumvents the difficulties encountered during the sintering of ceramics, i e. formation of hot spot, by radiation at industrially permissible frequency of 2.45GHz. Further, careful density measurement and microstructural characterisation of mm- wave and conventionally sintered samples by XRD, SEM and TEM has unequivocally demonstrated the effectiveness of mm-wave radiation for obtaining high density ceramics at lower sintering temperatures. Copyright (1998) Australasian Ceramic Society

  2. HAp physical investigation - the effect of sintering temperature

    International Nuclear Information System (INIS)

    Mohd Reusmaazran Yusof; Idris Besar; Rusnah Mustaffa; Cik Rohaida Che Hak

    2004-01-01

    The paper presents the effect of sintering temperature on the physical properties of porous hydroxyapatite (HAp). In this study, the HAp was prepared using polymeric sponge techniques with different binder concentration. The sintering process was carried out in air for temperature ranging from 1200 degree C to 1600 degree C. Different physical properties namely density and porosity were observed at different sintering temperatures. The HAp prepared with higher PVP binder showed a slightly decreased in apparent density with increasing sintering temperature, while those HAp prepared with lower PVP showed a slightly increase in apparent density with increasing sintering temperature. The total porosity was found to be approximately constant in the whole sintering temperature range. However, closed porosity decreases with increasing sintering temperature for HAp prepared by lower binder concentration. On the other hand, the HAp prepared by higher binder concentration HAp showed increasing closed porosity with increasing sintering temperature. Other features such as the influence of sintering temperatures on grain and strut also be presented in this paper. (Author)

  3. Sintering, microstructural and dilatometric studies of combustion synthesized Synroc phases

    International Nuclear Information System (INIS)

    Muthuraman, M.; Patil, K.C.; Senbagaraman, S.; Umarji, A.M.

    1996-01-01

    Sintering, microstructure, and linear thermal expansion properties of Synroc-B and constituent phases, viz. perovskite CaTiO 3 , zirconolite ZrTi 2 O 7 , hollandite (ideal formula BaAl2Ti 6 O 16 ) have been investigated. Synroc-B powder when pelletized and sintered at 1250 C for 2 h achieved >95% theoretical density. Sintered Synroc-B has a linear thermal expansion coefficient α of 8.72 x 10 -6 K -1 and Vicker's microhardness 9.88 GPa. The linear thermal expansion curves did not show any hysteresis indicating the absence of microcracking in the sintered bodies

  4. The electric conductivity of some forms of sintered synthetic zeolites

    International Nuclear Information System (INIS)

    Susic, M.; Petrovic, V.; Ristic, M.; Petranovic, N.

    1978-01-01

    Some forms of synthetic zeolites were sintered and their electric conductivity was measured. The conductivity was observed in correlation with the conductivity of non-sintered pressed samples. Also the change in microstructural constituents in the course of the process of sintering was observed with an optical microscope. It has been found that there is a considerable change in conductivity due to sintering as well as a change in the activation energy for conduction. Also the porosity is noticeably changed. A marked affect of the nature of counter ions on the electric conductivity is shown

  5. Properties, structure and machnining capabilities sintered corundum abrasives

    Directory of Open Access Journals (Sweden)

    Cz.J. Niżankowski

    2010-07-01

    Full Text Available The diversity of sintered corundum abrasives used in both bonded and in the embankment of abrasive tools currently poses substantialproblems for their choice of technology to specific tasks. Therefore performed a comparative study of ownership structures and capacitiesof elected representatives machnining sintered corundum abrasives of different generations, and this is normal sintered alumina,submicrocrystalline alumina sintered and nanocrystalline alumina sintered. Were studied some properties of a set of abrasive particles,physicochemical properties and structural and mechanical and technological properties. The studies used the method of microscopicmeasurement to determine the shape of abrasive particles, the pycnometer to determine the density of abrasive, a spectrometer todetermine the chemical composition of the magnetic analyzer for determining the magnetic fraction, scanning electron microscope toanalysis of abrasive grains and a special position to designate the machining capacity abrasive grains. The results showed a significantincrease in machining capacity sintered corundum abrasives with increasing degree of fragmentation of the crystallites sintered corundum abrasives and distinctive bands in the emerging microchip. The originality of the development provides a comparative summary ofproperties of sintered corundum abrasives of different generations and functions obtained by the author making the change in value indexof machininhcapacity grit from cutting speeds for different generations of sintered corundum.

  6. Interpretation of Frenkel’s theory of sintering considering evolution of activated pores: III. Determination of equilibrium sintering time

    Directory of Open Access Journals (Sweden)

    Yu C.L.

    2015-01-01

    Full Text Available In this article, the Frenkel’s theory of liquid-phase sintering was interpreted regarding pores as the activated volume. The mathematical model established by Nikolić et al. was used to infer the equilibrium sintering time at varied sintering temperatures during the isothermal sintering of codierite glass by Giess et al. Through the calculation, the equilibrium time at 800ºC, 820ºC, 840ºC and 860ºC is inferred to be 7014.42mins, 1569.65mins, 368.92mins and 114.61mins, respectively. The equilibrium time decreases as the temperature increases. And the theoretical value is in good accordance with the experimental results. Thus, the model established by Nikolić et al. can be applied successfully to predict the equilibrium sintering time of the cordierite glass at varied temperatures during isothermal sintering.

  7. Electric current activated/assisted sintering (ECAS): a review of patents 1906-2008

    International Nuclear Information System (INIS)

    Grasso, Salvatore; Sakka, Yoshio; Maizza, Giovanni

    2009-01-01

    The electric current activated/assisted sintering (ECAS) is an ever growing class of versatile techniques for sintering particulate materials. Despite the tremendous advances over the last two decades in ECASed materials and products there is a lack of comprehensive reviews on ECAS apparatuses and methods. This paper fills the gap by tracing the progress of ECAS technology from 1906 to 2008 and surveys 642 ECAS patents published over more than a century. It is found that the ECAS technology was pioneered by Bloxam (1906 GB Patent No. 9020) who developed the first resistive sintering apparatus. The patents were searched by keywords or by cross-links and were withdrawn from the Japanese Patent Office (342 patents), the United States Patent and Trademark Office (175 patents), the Chinese State Intellectual Property Office of P.R.C. (69 patents) and the World Intellectual Property Organization (12 patents). A subset of 119 (out of 642) ECAS patents on methods and apparatuses was selected and described in detail with respect to their fundamental concepts, physical principles and importance in either present ECAS apparatuses or future ECAS technologies for enhancing efficiency, reliability, repeatability, controllability and productivity. The paper is divided into two parts, the first deals with the basic concepts, features and definitions of basic ECAS and the second analyzes the auxiliary devices/peripherals. The basic ECAS is classified with reference to discharge time (fast and ultrafast ECAS). The fundamental principles and definitions of ECAS are outlined in accordance with the scientific and patent literature. (topical review)

  8. Xenon thermal behavior in sintered titanium nitride, foreseen inert matrix for GFR

    International Nuclear Information System (INIS)

    Bes, R.

    2010-11-01

    This work concerns the generation IV future nuclear reactors such as gas-cooled fast reactor (GFR) for which refractory materials as titanium nitride (TiN) are needed to surround fuel and act as a fission product diffusion barrier. This study is about Xe thermal behavior in sintered titanium nitride. Microstructure effects on Xe behavior have been studied. In this purpose, several syntheses have been performed using different sintering temperatures and initial powder compositions. Xenon species have been introduced into samples by ionic implantation. Then, samples were annealed in temperature range from 1300 C to 1600 C, these temperatures being the accidental awaited temperature. A transport of xenon towards sample surface has been observed. Transport rate seems to be slow down when increasing sintering temperature. The composition of initial powder and the crystallographic orientation of each considered grain also influence xenon thermal behavior. Xenon release has been correlated with material oxidation during annealing. Xenon bubbles were observed. Their size is proportional with xenon concentration and increases with annealing temperature. Several mechanisms which could explain Xe intragranular mobility in TiN are proposed. In addition with experiments, very low Xe solubility in TiN has been confirmed by ab initio calculations. So, bi-vacancies were found to be the most favoured Xe incorporation sites in this material. (author)

  9. Reconstruction of Optical Thickness from Hoffman Modulation Contrast Images

    DEFF Research Database (Denmark)

    Olsen, Niels Holm; Sporring, Jon; Nielsen, Mads

    2003-01-01

    Hoffman microscopy imaging systems are part of numerous fertility clinics world-wide. We discuss the physics of the Hoffman imaging system from optical thickness to image intensity, implement a simple, yet fast, reconstruction algorithm using Fast Fourier Transformation and discuss the usability...... of the method on a number of cells from a human embryo. Novelty is identifying the non-linearity of a typical Hoffman imaging system, and the application of Fourier Transformation to reconstruct the optical thickness....

  10. Lead Thickness Measurements

    International Nuclear Information System (INIS)

    Rucinski, R.

    1998-01-01

    The preshower lead thickness applied to the outside of D-Zero's superconducting solenoid vacuum shell was measured at the time of application. This engineering documents those thickness measurements. The lead was ordered in sheets 0.09375-inch and 0.0625-inch thick. The tolerance on thickness was specified to be +/- 0.003-inch. The sheets all were within that thickness tolerance. The nomenclature for each sheet was designated 1T, 1B, 2T, 2B where the numeral designates it's location in the wrap and 'T' or 'B' is short for 'top' or 'bottom' half of the solenoid. Micrometer measurements were taken at six locations around the perimeter of each sheet. The width,length, and weight of each piece was then measured. Using an assumed pure lead density of 0.40974 lb/in 3 , an average sheet thickness was calculated and compared to the perimeter thickness measurements. In every case, the calculated average thickness was a few mils thinner than the perimeter measurements. The ratio was constant, 0.98. This discrepancy is likely due to the assumed pure lead density. It is not felt that the perimeter is thicker than the center regions. The data suggests that the physical thickness of the sheets is uniform to +/- 0.0015-inch.

  11. Eddy current technologies for thick metal structures

    International Nuclear Information System (INIS)

    Takagi, Toshiyuki; Endo, Hisashi

    2004-01-01

    One of approach of an eddy current testing (ECT) for thick metal structures is introduced. The detection limit of ECT is capable of enlarging thick more than 10 mm, which is ordinarily about 5 mm, by the design of probe. On the basis of results of numerical analysis, the defect detection in thick and shape is evaluated by the distribution of experimental ECT signals. The problems of ECT for thick metal structures and measures, approach to probe design, the specifications of probe, evaluation of experimental results and defect detection are described. By ECT fast simulator, good slit sharp is simulated in the case of 10 and 20 mm of EDM slit length and 5, 10 and 15 mm of slit height. (S.Y.)

  12. Laser Surface Treatment of Sintered Alumina

    Science.gov (United States)

    Hagemann, R.; Noelke, C.; Kaierle, S.; Wesling, V.

    Sintered alumina ceramics are used as refractory materials for industrial aluminum furnaces. In this environment the ceramic surface is in permanent contact with molten aluminum resulting in deposition of oxidic material on its surface. Consequently, a lower volume capacity as well as thermal efficiency of the furnaces follows. To reduce oxidic adherence of the ceramic material, two laser-based surface treatment processes were investigated: a powder- based single-step laser cladding and a laser surface remelting. Main objective is to achieve an improved surface quality of the ceramic material considering the industrial requirements as a high process speed.

  13. Computer Modeling of Direct Metal Laser Sintering

    Science.gov (United States)

    Cross, Matthew

    2014-01-01

    A computational approach to modeling direct metal laser sintering (DMLS) additive manufacturing process is presented. The primary application of the model is for determining the temperature history of parts fabricated using DMLS to evaluate residual stresses found in finished pieces and to assess manufacturing process strategies to reduce part slumping. The model utilizes MSC SINDA as a heat transfer solver with imbedded FORTRAN computer code to direct laser motion, apply laser heating as a boundary condition, and simulate the addition of metal powder layers during part fabrication. Model results are compared to available data collected during in situ DMLS part manufacture.

  14. SEM hot stage sintering of UO2

    International Nuclear Information System (INIS)

    Miller, D.J.

    1976-06-01

    The sintering of hyperstoichiometric uranium dioxide powder compacts, in the hot stage of a scanning electron microscope, was continuously monitored using 16 mm time lapse movies. From alumina microspheres placed on the surface of the compacts, shrinkage measurements were obtained. Converting shrinkage measurements into densification profiles indicates that a maximum densification rate is reached at a critical density, independent of the constant heating rates. At temperatures above 1350 0 C, the movement of the reference microspheres made shrinkage measurements impossible. It is believed the evolution of UO 3 gas from hyperstoichiometric UO 2 is the cause of this limitation

  15. Selective laser sintering in biomedical engineering.

    Science.gov (United States)

    Mazzoli, Alida

    2013-03-01

    Selective laser sintering (SLS) is a solid freeform fabrication technique, developed by Carl Deckard for his master's thesis at the University of Texas, patented in 1989. SLS manufacturing is a technique that produces physical models through a selective solidification of a variety of fine powders. SLS technology is getting a great amount of attention in the clinical field. In this paper the characteristics features of SLS and the materials that have been developed for are reviewed together with a discussion on the principles of the above-mentioned manufacturing technique. The applications of SLS in tissue engineering, and at-large in the biomedical field, are reviewed and discussed.

  16. Powder densification maps in Selective Laser Sintering

    International Nuclear Information System (INIS)

    Bourell, D.; Wohlert, M.; Harlan, N.; Beaman, J.; Das, S.

    2002-01-01

    Selective Laser Sintering (SLS) is a manufacturing process in which a part is produced without the need for part-specific tooling. It competes effectively with other manufacturing processes when part geometry is complex and the production run is not large. Traditionally, this was limited to prototype production, although tooling applications are now appearing. This paper describes several applications of powder densification maps to advance solutions in direct SLS of metallic and ceramic powders. Time-dependent plasticity issues arise in pre-processing of powder to make it suitable for SLS and in post-processing of SLS parts to obtain desired density. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  17. Education and "Thick" Epistemology

    Science.gov (United States)

    Kotzee, Ben

    2011-01-01

    In this essay Ben Kotzee addresses the implications of Bernard Williams's distinction between "thick" and "thin" concepts in ethics for epistemology and for education. Kotzee holds that, as in the case of ethics, one may distinguish between "thick" and "thin" concepts of epistemology and, further, that this distinction points to the importance of…

  18. Multiphysics modeling of selective laser sintering/melting

    Science.gov (United States)

    Ganeriwala, Rishi Kumar

    A significant percentage of total global employment is due to the manufacturing industry. However, manufacturing also accounts for nearly 20% of total energy usage in the United States according to the EIA. In fact, manufacturing accounted for 90% of industrial energy consumption and 84% of industry carbon dioxide emissions in 2002. Clearly, advances in manufacturing technology and efficiency are necessary to curb emissions and help society as a whole. Additive manufacturing (AM) refers to a relatively recent group of manufacturing technologies whereby one can 3D print parts, which has the potential to significantly reduce waste, reconfigure the supply chain, and generally disrupt the whole manufacturing industry. Selective laser sintering/melting (SLS/SLM) is one type of AM technology with the distinct advantage of being able to 3D print metals and rapidly produce net shape parts with complicated geometries. In SLS/SLM parts are built up layer-by-layer out of powder particles, which are selectively sintered/melted via a laser. However, in order to produce defect-free parts of sufficient strength, the process parameters (laser power, scan speed, layer thickness, powder size, etc.) must be carefully optimized. Obviously, these process parameters will vary depending on material, part geometry, and desired final part characteristics. Running experiments to optimize these parameters is costly, energy intensive, and extremely material specific. Thus a computational model of this process would be highly valuable. In this work a three dimensional, reduced order, coupled discrete element - finite difference model is presented for simulating the deposition and subsequent laser heating of a layer of powder particles sitting on top of a substrate. Validation is provided and parameter studies are conducted showing the ability of this model to help determine appropriate process parameters and an optimal powder size distribution for a given material. Next, thermal stresses upon

  19. Improved critical current densities in bulk FeSe superconductor using ball milled powders and high temperature sintering

    Energy Technology Data Exchange (ETDEWEB)

    Muralidhar, M.; Furutani, K.; Murakami, M. [Graduate School of Science and Engineering, Superconducting Materials Laboratory, Shibaura Institute of Technology, Tokyo (Japan); Kumar, Dinesh; Rao, M.S. Ramachandra [Department of Physics, Nano Functional Materials Technology Centre and Materials Science Research Centre, Indian Institute of Technology Madras, Chennai (India); Koblischka, M.R. [Institute of Experimental Physics, Saarland University, Saarbruecken (Germany)

    2016-12-15

    The present study is investigating the effect of high temperature sintering combined with ball milled powders for the preparation of FeSe material via solid state sintering technique. The commercial powders of Fe (99.9% purity) and Se (99.9% purity) were mixed in a nominal ratio Fe:Se = 1:1 and thoroughly ground and ball-milled in a glove box during 6 h. Then, the powder mixture was pressed into pellets of 5 mm in diameter and 2 mm thickness using an uniaxial pressure of 100 MPa. The samples were sealed in quartz tubes and sintered at 600 C for 24 h. Then, the pellets were again thoroughly ground and ball-milled in the glove box and pressed into pellets, and the final sintering was performed at two different temperatures, namely at 900 C for 24 h and at 950 C for 24 h. X-ray diffraction results confirmed that both samples showed mainly of the β-FeSe with tetragonal structure. The temperature dependence of magnetization (M-T) curves revealed a sharp superconducting transition T{sub c,} {sub onset} = 8.16 K for the sample sintered at 900 C. Further, scanning electron microscopy observations proved that samples sintered at 900 C show a platelike grain structure with high density. As a result, improved irreversibility fields around 5 T and the critical current density (J{sub c}) values of 6252 A cm{sup -2} at 5 K and self-field are obtained. Furthermore, the normalized volume pinning force versus the reduced field plots indicated a peak position at 0.4 for the sample sintered at 900 C. Improved flux pinning and the high J{sub c} values are attributed to the textured microstructure of the material, produced by a combination of high temperature sintering and ball milling. (copyright 2016 The Authors. Phys. Status Solidi A published by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Corrosion behaviour of sintered duplex stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Utrilla, M. Victoria; Urena, Alejandro; Otero, Enrique; Munez, Claudio Jose [Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, C/ Tulipan s/n, 28933 Mostoles, Madrid (Spain)

    2004-07-01

    Duplex austenite-ferrite stainless steels were prepared by mixing austenitic (316L) and ferritic (434L) atomized powders. Although different 316L/434L ratios were prepared, present work centred its study on 50% ferrite - 50% austenite sintered steel. The powders were mixed and pressed at 700 MPa and sintered at 1250 deg. C for 30 min in vacuum. The cooling rate was 5 deg. C/min. Solution treatment was carried out to homogenize the microstructure at 1100 deg. C during 20 min. A microstructural study of the material in solution was performed, evaluating the microstructure, proportion and shape of porosity, and ferrite percentage. This last was measured by two methods, quantitative metallography and Fischer ferrito-metry. The materials were heat treated in the range of 700 to 1000 deg. C, for 10, 30 and 60 min and water quenched, to study the microstructural changes and the influence on the intergranular corrosion resistance. The method used to evaluate the sensitization to the intergranular corrosion was the electrochemical potentio-kinetic reactivation procedure (EPR). The test solution was 0.5 M H{sub 2}SO{sub 4} + 0,01 M KSCN at 30 deg. C. The criterion used to evaluate the sensitization was the ratio between the maximum reactivation density (Ir) and the maximum activation density (Ia). The results of the electrochemical tests were discussed in relation with the microstructures observed at the different heat treatments. (authors)

  1. Effects of Sintering Temperature on the Density And Porosity of ...

    African Journals Online (AJOL)

    Effects of sintering temperature on the density and porosity of sodium chloride preforms for alu- minium foam manufacturing have been investigated. Cold pressed salt preforms were sintered at 30, 760 and 790 and di erent times ranging between 6- 18 hours in a carbolite furnace at a heating rate of 5/minute. The Results of ...

  2. Sintering of Multilayered Porous Structures: Part I-Constitutive Models

    DEFF Research Database (Denmark)

    Olevsky, Eugene; Tadesse Molla, Tesfaye; Frandsen, Henrik Lund

    2013-01-01

    Theoretical analyses of shrinkage and distortion kinetics during sintering of bilayered porous structures are carried out. The developed modeling framework is based on the continuum theory of sintering; it enables the direct assessment of the cofiring process outcomes and of the impact of process...

  3. Monitoring Sintering Burn-Through Point Using Infrared Thermography

    Directory of Open Access Journals (Sweden)

    Francisco G. Bulnes

    2013-08-01

    Full Text Available Sintering is a complex industrial process that applies heat to fine particles of iron ore and other materials to produce sinter, a solidified porous material used in blast furnaces. The sintering process needs to be carefully adjusted, so that the combustion zone reaches the bottom of the material just before the discharge end. This is known as the burnthrough point. Many different parameters need to be finely tuned, including the speed and the quantities of the materials mixed. However, in order to achieve good results, sintering control requires precise feedback to adjust these parameters. This work presents a sensor to monitor the sintering burn-through point based on infrared thermography. The proposed procedure is based on the acquisition of infrared images at the end of the sintering process. At this position, infrared images contain the cross-section temperatures of the mixture. The objective of this work is to process this information to extract relevant features about the sintering process. The proposed procedure is based on four steps: key frame detection, region of interest detection, segmentation and feature extraction. The results indicate that the proposed procedure is very robust and reliable, providing features that can be used effectively to control the sintering process.

  4. Sintering of uranium dioxide obtained by continuous precipitation of AUC

    International Nuclear Information System (INIS)

    Amaya, C.D.; Sterba, M.E.; Russo, D.O.

    1993-01-01

    The Nuclear Materials Division in Bariloche Atomic Center evaluates the ceramic behaviour of UO 2 powders obtained from continuously precipitated and reduced AUC (Ammonium Uranyl Tri Carbonate). An analysis is made of powder characteristics (particle morphology and size distribution and specific area) on behaviour of UO 2 during sintering (compaction, sintering, pore and grain microstructure, etc.). 1 ref

  5. CALCIUM OXIDE SINTERING IN ATMOSPHERES CONTAINING WATER AND CARBON DIOXIDE

    Science.gov (United States)

    The paper gives results of measurements of the effects of water vapor and CO2 on the sintering rate of nascent CaO, as a function of partial pressure and temperature using CaO prepared by rapid decomposition of CaCO3 and CA(OH)2. Each gas strongly catalyzed the sintering process ...

  6. Effect of sintering temperature and heating mode on consolidation of ...

    Indian Academy of Sciences (India)

    ratures ranging from 570–630 ◦C. Microwave sintering at a heating rate of as high as 22◦. C/min resulted in ... The effect of heating mode and sintering temperature are discussed .... the compacts. This is attributed to the Zn evaporated from the.

  7. Microstructure evolution during pressureless sintering of bulk oxide ceramics

    Directory of Open Access Journals (Sweden)

    Karel Maca

    2009-06-01

    Full Text Available The author’s experience concerning the infl uence of the choice of different pressureless heating schedules on the fi nal microstructure of oxide ceramic materials is summarized in the paper. Alumina, ceria, strontium titanate, as well as tetragonal (3 mol% Y2O3 and cubic (8 mol% Y2O3 zirconia were cold isostatically pressed or injection moulded and pressureless sintered with different heating schedules – namely with Constant-Rate of Heating with different dwell temperatures (CRH, with Rate-Controlled Sintering (RCS and with Two-Step Sintering (TSS. It was examined whether some of these three sintering schedules, with the same fi nal density achieved, can lead to a decrease of the grain size of sintered ceramics. The results showed that only TSS (and only for selected materials brought significant decrease of the grain size.

  8. Densification of LSGM electrolytes using activated microwave sintering

    Science.gov (United States)

    Kesapragada, S. V.; Bhaduri, S. B.; Bhaduri, S.; Singh, P.

    Lanthanum gallate doped with alkaline rare earths (LSGM) powders were densified using an activated microwave sintering process for developing a dense stable electrolyte layer for applications in intermediate temperature-solid oxide fuel cells (IT-SOFCs). Due to heat generation in situ, the process of sintering gets activated with faster kinetics compared to a conventional sintering process. The effect of various microwave process parameters on the microstructure and phase formation was studied. The sintered pellets were characterized using scanning electron microscopy-energy dispersive analysis (SEM-EDAX), and X-ray diffraction (XRD). The density of LSGM pellets microwave sintered at 1350 °C for 20 min is greater than 95% theoretical density with a fine grained microstructure (˜2-3 μm) and without the presence of other phase(s).

  9. Ash chemistry and sintering, verification of the mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M; Skrifvars, B J; Backman, R; Lauren, T; Uusikartano, T; Malm, H; Stenstroem, P; Vesterkvist, M [Aabo Akademi, Turku (Finland). Combustion Chemistry Research Group

    1997-10-01

    In this project four sintering mechanisms have been studied, i.e., partial melting with a viscous liquid, partial melting with a non-viscous liquid, chemical reaction sintering and solid state sintering. The work has aimed at improving the understanding of ash sintering mechanisms and quantifying their role in combustion and gasification. The work has been oriented in particular on the understanding of biomass ash behavior. The work has not directly focused on any specific technical application. However, results can also be applied on other fuels such as brown coal, petroleum coke, black liquor and different types of wastes (PDF, RDF, MSW). During 1996 the work has focused on identifying bed agglomeration mechanisms and analysing bed agglomerates in both full scale and lab scale FB reactors, as well as comparing how well the compression strength based sintering test can predict bed agglomeration in an FB furnace. (orig.)

  10. Sintering unalloyed titanium in DC electrical abnormal glow discharge

    Directory of Open Access Journals (Sweden)

    Allan Seeber

    2010-03-01

    Full Text Available Powder metallurgy is widely used in the manufacture of components that have complex geometry. The good dimensional control, reduction in manufacturing steps and operating costs which has favored the use of this technique for manufacturing of titanium alloys components. However, the high affinity of this material with oxygen hinders strongly the sintering process. For this, the sintering associated with plasma technology can be considered an alternative technique for the processing of this material. The strict control of sintering atmosphere performed at low pressures and the reactive species present in the plasma environment can help to improve the sintering of this material. The results presented in this paper show a good correlation between the parameters used for the compaction of the samples and the microstructure develop during the plasma sintering of samples. The microstructure of the plasma assisted samples is also affected by the particular configuration used in the plasma reactor.

  11. Sintering with a chemical reaction as applied to uranium monocarbide

    International Nuclear Information System (INIS)

    Accary, A.; Caillat, R.

    1960-01-01

    The present paper provides a survey of different investigations whose aim was the preparation and fabrication of uranium monocarbide for nuclear use. If a chemical reaction takes place in the sample during the sintering operation, it may be expected that the atom rearrangements involved in this reaction should favour the sintering process and thereby lower the temperature needed to yield a body of a given density. With this hypothesis in mind, the following methods have been studied: - Sintering of U-C mixtures; - Sintering of UO 2 -C mixtures; - Hot pressing of U-C mixtures; - Extrusion of U-C mixtures. To generalize our result, it could be said that a chemical reaction does not lead to high densification, if one depends on a simple contact between discrete particles. On the contrary, a chemical reaction can help sintering if, as our hot pressing experiments shows, the densification can be achieved prior to the reaction. (author) [fr

  12. Preliminary investigation of liquid phase sintering in ferrous systems

    International Nuclear Information System (INIS)

    Klein, J.

    1975-04-01

    Liquid phase sintering was utilized to achieve, by a simple compaction and sintering procedure involving short times and moderate temperatures, a virtually full dense high carbon Fe:C alloy and high boron Fe:B alloy. Parameters such as powder characteristics and mixing, compacting pressure, heating program and the liquid phase fraction were found to influence the sintered density. The response of the Fe:C alloy to a heat treatment is reported along with preliminary experiments in the iron base ternary system Fe:W:C. Residual porosities observed in microstructures of certain liquid phase sintered compacts were accounted for by a proposed capillary flow of the liquid phase and a local densification competing against an overall densification. Some general recommendations are made for liquid phase sintering of powder aggregates. 15 fig., 7 tables

  13. Effect of particle size distribution on sintering of tungsten

    International Nuclear Information System (INIS)

    Patterson, B.R.; Griffin, J.A.

    1984-01-01

    To date, very little is known about the effect of the nature of the particle size distribution on sintering. It is reasonable that there should be an effect of size distribution, and theory and prior experimental work examining the effects of variations in bimodal and continuous distributions have shown marked effects on sintering. Most importantly, even with constant mean particle size, variations in distribution width, or standard deviation, have been shown to produce marked variations in microstructure and sintering rate. In the latter work, in which spherical copper powders were blended to produce lognormal distributions of constant geometric mean particle size by weight frequency, blends with larger values of geometric standard deviation, 1nσ, sintered more rapidly. The goals of the present study were to examine in more detail the effects of variations in the width of lognormal particle size distributions of tungsten powder and determine the effects of 1nσ on the microstructural evolution during sintering

  14. Powder metallurgy: Solid and liquid phase sintering of copper

    Science.gov (United States)

    Sheldon, Rex; Weiser, Martin W.

    1993-01-01

    Basic powder metallurgy (P/M) principles and techniques are presented in this laboratory experiment. A copper based system is used since it is relatively easy to work with and is commercially important. In addition to standard solid state sintering, small quantities of low melting metals such as tin, zinc, lead, and aluminum can be added to demonstrate liquid phase sintering and alloy formation. The Taguchi Method of experimental design was used to study the effect of particle size, pressing force, sintering temperature, and sintering time. These parameters can be easily changed to incorporate liquid phase sintering effects and some guidelines for such substitutions are presented. The experiment is typically carried out over a period of three weeks.

  15. Examining Mechanical Strength Characteristics of Selective Inhibition Sintered HDPE Specimens Using RSM and Desirability Approach

    Science.gov (United States)

    Rajamani, D.; Esakki, Balasubramanian

    2017-09-01

    Selective inhibition sintering (SIS) is a powder based additive manufacturing (AM) technique to produce functional parts with an inexpensive system compared with other AM processes. Mechanical properties of SIS fabricated parts are of high dependence on various process parameters importantly layer thickness, heat energy, heater feedrate, and printer feedrate. In this paper, examining the influence of these process parameters on evaluating mechanical properties such as tensile and flexural strength using Response Surface Methodology (RSM) is carried out. The test specimens are fabricated using high density polyethylene (HDPE) and mathematical models are developed to correlate the control factors to the respective experimental design response. Further, optimal SIS process parameters are determined using desirability approach to enhance the mechanical properties of HDPE specimens. Optimization studies reveal that, combination of high heat energy, low layer thickness, medium heater feedrate and printer feedrate yielded superior mechanical strength characteristics.

  16. Three-dimensional simulation of viscous-flow agglomerate sintering.

    Science.gov (United States)

    Kirchhof, M J; Schmid, H -J; Peukert, W

    2009-08-01

    The viscous-flow sintering of different agglomerate particle morphologies is studied by three-dimensional computer simulations based on the concept of fractional volume of fluid. For a fundamental understanding of particle sintering characteristics, the neck growth kinetics in agglomerate chains and in doublets consisting of differently sized primary particles is investigated. Results show that different sintering contacts in agglomerates even during the first stages are not completely independent from each other, even though differences are small. The neck growth kinetics of differently sized primary particles is determined by the smaller one up to a size difference by a factor of approximately 2, whereas for larger size differences, the kinetics becomes faster. In particular, the agglomerate sintering kinetics is investigated for particle chains of different lengths and for different particle morphologies each having ten primary particles and nine initial sintering contacts. For agglomerate chains, the kinetics approximately can be normalized by using the radius of the fully coalesced sphere. In general, different agglomerate morphologies show equal kinetics during the first sintering stages, whereas during advanced stages, compact morphologies show significantly faster sintering progress than more open morphologies. Hence, the overall kinetics cannot be described by simply using constant morphology correction factors such as fractal dimension or mean coordination number which are used in common sintering models. However, for the first stages of viscous-flow agglomerate sintering, which are the most important for many particle processes, a sintering equation is presented. Although we use agglomerates consisting of spherical primary particles, our methodology can be applied to other aggregate geometries as well.

  17. Ocean Sediment Thickness Contours

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ocean sediment thickness contours in 200 meter intervals for water depths ranging from 0 - 18,000 meters. These contours were derived from a global sediment...

  18. Investigation of Top/Bottom electrode and Diffusion Barrier Layer for PZT Thick Film MEMS Sensors

    DEFF Research Database (Denmark)

    Hindrichsen, Christian Carstensen; Pedersen, Thomas; Thomsen, Erik Vilain

    2008-01-01

    Top and bottom electrodes for screen printed piezoelectric lead zirconate titanate, Pb(ZrxTi1 - x)O3 (PZT) thick film are investigated with respect to future MEMS devices. Down to 100 nm thick E-beam evaporated Al and Pt films are patterned as top electrodes on the PZT using a lift-off process...... with a line width down to 3 μ m. A 700 nm thick ZrO2 layer as insolating diffusion barrier layer is found to be insufficient as barrier layer for PZT on a silicon substrate sintered at 850°C. EDX shows diffusion of Si into the PZT layer....

  19. The influence of green microstructure and sintering parameters on precipitation process during copper-nickel-zinc ferrites sintering

    International Nuclear Information System (INIS)

    Barba, A.; Clausell, C.; Jarque, J. C.; Monzo, M.

    2014-01-01

    Microstructural changes that occur during heat treatment of copper-nickel-zinc ferrites have been studied. The process of precipitation of the two types of crystals that occur during the sintering process has been analyzed. It is found that this process depends on dry relative density of the press specimens and on the following sintering parameters: sintering temperature, sintering time and cooling rate of the thermal cycle. Crystal precipitates characterization have been done by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These techniques have allowed to determine the nature of these crystals, which in this case correspond to zinc and copper oxides. It has been used two chemical reactions to explain the bulk precipitation and subsequent re-dissolution of these crystal precipitates during sintering. (Author)

  20. Rapid rate sintering of nanocrystalline ZrO2-3 mol% Y2O3

    International Nuclear Information System (INIS)

    Chen, D.J.; Mayo, M.J.

    1996-01-01

    Conventional ramp-and-hold sintering with a wide range of heating rates was conducted on submicrometer and nanocrystalline ZrO 2 -3 mol% Y 2 O 3 powder compacts. Although rapid heating rates have been reported to produce high density/fine grain size products for many submicrometer and smaller starting powders, the application of this technique to ZrO 2 -3 mol% Y 2 O 3 produced mixed results. In the case of submicrometer ZrO 2 -3 mol% Y 2 O 3 , neither densification nor grain growth was affected by the heating rate used. In the case of nanocrystalline ZrO 2 -3 mol% Y 2 O 3 , fast heating rates severely retarded densification and had a minimal effect on grain growth. The large adverse effect of fast heating rates on the densification of the nanocrystalline powder was traced to a thermal gradient/differential densification effect. Microstructural evidence suggests that the rate of densification greatly exceeded the rate of heat transfer in this material; consequently, the sample interior was not able to densify before being geometrically constrained by a fully dense shell which formed at the sample exterior. This finding implies that rapid rate sintering will meet severe practical constraints in the manufacture of bulk nanocrystalline ZrO 2 -3 mol% Y 2 O 3 specimens

  1. Scanning pattern angle effect on the resulting properties of selective laser sintered monolayers of Cu-Sn-Ni powder

    Science.gov (United States)

    Sabelle, Matías; Walczak, Magdalena; Ramos-Grez, Jorge

    2018-01-01

    Laser-based layer manufacturing of metals, also known as additive manufacturing, is a growing research field of academic and industrial interest. However, in the associated laser-driven processes (i.e. selective laser sintering (SLS) or melting (SLM)), optimization of some parameters has not been fully explored. This research aims at determining how the angle of laser scanning pattern (i.e. build orientation) in SLS affects the mechanical properties and structure of an individual Cu-Sn-Ni alloy metallic layer sintered in the process. Experiments consist in varying the angle of the scanning pattern (0°, 30°, 45° 60° and 90° relative to the transverse dimension of the piece), at constant scanning speed and laser beam power, producing specimens of different thicknesses. A noticeable effect of the scan angle on the mechanical strength and degree of densification of the sintered specimens is found. Thickness of the resulting monolayer correlates negatively with increasing scan angle, whereas relative density correlates positively. A minimum porosity and maximum UTS are found at the angle of 60°. It is concluded that angle of the scanning pattern angle plays a significant role in SLS of metallic monolayers.

  2. Comparison of Ti(C,N)-based cermets processed by hot-pressing sintering and conventional pressureless sintering

    International Nuclear Information System (INIS)

    Xu, Qingzhong; Ai, Xing; Zhao, Jun; Qin, Weizhen; Wang, Yintao; Gong, Feng

    2015-01-01

    Highlights: • The HP sintered Ti(C,N)-based cermets exhibit high hardness with fine grain size. • The PLS sintered cermets possess high mechanical properties with low porosity. • The applied pressure can rearrange particles and contribute to grain refinement. • The heating rate can greatly affect the solid and liquid phase sintering of cermets. - Abstract: A suitable sintering method is important to obtain the Ti(C,N)-based cermets with superior properties. In this paper, Ti(C,N)-based cermets were fabricated by hot-pressing sintering (HP) and conventional pressureless sintering (PLS) technology, respectively, to investigate the influence of different sintering methods on the microstructure and mechanical properties of cermets materials. The microstructure, fracture morphology, indention cracks and phase composition were observed and detected using scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The transverse rupture strength (TRS), Vickers hardness (HV) and fracture toughness (K IC ) were also measured. The results reveal that all of the Ti(C,N)-based cermets exhibit core–rim microstructures with black cores, white cores and grey rims embedded into metal binder phases. The grain size of the samples fabricated by HP is much finer and the structure is more compact than those fabricated by PLS, while there exist pores in the HP sintered samples. The sintering process has no influence on the phase composition of cermets, but affects the phase content and crystallinity. The samples fabricated by PLS present higher transverse rupture strength, fracture toughness and density than samples fabricated by HP. However, the HP sintered samples possess a higher hardness

  3. Influence of sintering temperature on the properties of pulsed electric current sintered hybrid coreshell powders

    Czech Academy of Sciences Publication Activity Database

    Mahmed, N.; Larismaa, J.; Heczko, Oleg; Cura, M.E.; Hannula, S.-P.

    2013-01-01

    Roč. 33, č. 12 (2013), s. 2233-2239 ISSN 0955-2219 R&D Projects: GA ČR(CZ) GAP107/11/0391 Institutional support: RVO:68378271 Keywords : sintering * silver * iron oxide * SiO 2 * phase transformation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.307, year: 2013 http://dx.doi.org/10.1016/j.jeurceramsoc.2012.12.023

  4. A study of emission property and microstructure of rare earth oxide-molybdenum cermet cathode materials made by spark plasma sintering

    International Nuclear Information System (INIS)

    Wang Jinshu; Li Hongyi; Yang Sa; Cui Ying; Zhou Meiling

    2004-01-01

    A fast sintering method, spark plasma sintering (SPS) was used for the synthesis of rare earth oxide-molybdenum cathode material. The secondary emission property, microstructure, and phase constitution of materials have been studied in this paper. The experimental results show that the maximum secondary emission coefficient of this material can be high to 3.84, much higher than that of rare earth oxide-molybdenum cathode made by traditional sintering method. The grain size is less than 1 μm and rare earth distributed evenly in the material. After the material was activated at 1600 deg. C, a 4 μm layer of rare earth oxide which leads to the high secondary emission coefficient of the material, is formed on the surface of the cathode

  5. Sintering and microstructure evolution in columnar thermal barrier coatings

    International Nuclear Information System (INIS)

    Krishnamurthy, Ramanathan; Srolovitz, David J.

    2009-01-01

    Sintering of thermal barrier coatings changes their key properties, such as thermal conductivity and thermal shock resistance, thus adversely impacting their reliability. We present a novel modeling approach to study the evolution of coating structure during sintering. We model the sintering of individual columns using a thermodynamic principle, and incorporate the center-to-center approach rates for the columns calculated using this principle in a larger scale discrete dynamics model for the evolution of a large number of columns. Surface energies, grain boundary energies and strain energies associated with the deformation of the columns are all included in this framework, while sintering is assumed to occur by the concerted action of surface and grain boundary diffusion. Two sets of initial conditions corresponding to different extents of pre-sintering among neighboring columns are considered. When the extent of pre-sintering is small, we observe that small clusters containing 5-20 columns are formed. In contrast, where a larger amount of pre-sintering exists, we observe, especially at large column densities, that clusters containing 50-100 columns separated by large inter-cluster pores/channels that appear to organize themselves into a network are formed. These observations are in good agreement with recently published experimental observations. We also explain how these results can explain the development of a 'mud-crack'-like pattern

  6. Spark plasma sintering of titanium aluminide intermetallics and its composites

    Science.gov (United States)

    Aldoshan, Abdelhakim Ahmed

    Titanium aluminide intermetallics are a distinct class of engineering materials having unique properties over conventional titanium alloys. gamma-TiAl compound possesses competitive physical and mechanical properties at elevated temperature applications compared to Ni-based superalloys. gamma-TiAl composite materials exhibit high melting point, low density, high strength and excellent corrosion resistance. Spark plasma sintering (SPS) is one of the powder metallurgy techniques where powder mixture undergoes simultaneous application of uniaxial pressure and pulsed direct current. Unlike other sintering techniques such as hot iso-static pressing and hot pressing, SPS compacts the materials in shorter time (< 10 min) with a lower temperature and leads to highly dense products. Reactive synthesis of titanium aluminide intermetallics is carried out using SPS. Reactive sintering takes place between liquid aluminum and solid titanium. In this work, reactive sintering through SPS was used to fabricate fully densified gamma-TiAl and titanium aluminide composites starting from elemental powders at different sintering temperatures. It was observed that sintering temperature played significant role in the densification of titanium aluminide composites. gamma-TiAl was the predominate phase at different temperatures. The effect of increasing sintering temperature on microhardness, microstructure, yield strength and wear behavior of titanium aluminide was studied. Addition of graphene nanoplatelets to titanium aluminide matrix resulted in change in microhardness. In Ti-Al-graphene composites, a noticeable decrease in coefficient of friction was observed due to the influence of self-lubrication caused by graphene.

  7. Studies on the sintering behaviour of uranium dioxide powder compacts

    International Nuclear Information System (INIS)

    Das, P.; Chowdhury, R.

    1988-01-01

    Uranium dioxide fuel pellets are normally made from their precursor ammonium diuranate, followed by calcination, subsequent reduction to sinterable grade powders and a post operation treatment of pressing and sintering. The low temperature calcined powders, usually exhibiting non-crystalline behaviour (under X-ray diffraction studies) progressively transforms into a crystalline variety on subsequent heat treatment at higher temperature. It is observed however that powders calcined between 800 to 900 0 C exhibit enhanced densification behaviour when sintered at higher temperatures. The isothermal shrinkage versus time plot of the sintered compacts are well described by a hyperbolic relationship which takes care of the observed shrinkage (λ) as caused due to a cumulative effect from the initial sintering of the powder compacts at zero time (α) and that caused due to the structural transformation from a non-crystalline modification with increased thermal treatment (β). The derived equation is a modification of the sintering mechanism of the viscous flow type proposed by Frenkel, involving sintering of an amorphous phase, the viscosity of the latter is presumed to increase with increasing thermal treatment to assume the final modified form as λ=t/(α+βt), where t = time, λ = shrinkage and α and β are the unknown parameters. (orig.)

  8. Removable partial denture alloys processed by laser-sintering technique.

    Science.gov (United States)

    Alageel, Omar; Abdallah, Mohamed-Nur; Alsheghri, Ammar; Song, Jun; Caron, Eric; Tamimi, Faleh

    2018-04-01

    Removable partial dentures (RPDs) are traditionally made using a casting technique. New additive manufacturing processes based on laser sintering has been developed for quick fabrication of RPDs metal frameworks at low cost. The objective of this study was to characterize the mechanical, physical, and biocompatibility properties of RPD cobalt-chromium (Co-Cr) alloys produced by two laser-sintering systems and compare them to those prepared using traditional casting methods. The laser-sintered Co-Cr alloys were processed by the selective laser-sintering method (SLS) and the direct metal laser-sintering (DMLS) method using the Phenix system (L-1) and EOS system (L-2), respectively. L-1 and L-2 techniques were 8 and 3.5 times more precise than the casting (CC) technique (p laser-sintered and cast alloys were biocompatible. In conclusion, laser-sintered alloys are more precise and present better mechanical and fatigue properties than cast alloys for RPDs. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1174-1185, 2018. © 2017 Wiley Periodicals, Inc.

  9. Fabrication of tubed functionally graded material by slurry dipping process. Thickness control of dip-coated layer

    International Nuclear Information System (INIS)

    Watanabe, Ryuzo

    1997-03-01

    In order to obtain long life fuel cladding tubes for the fast breeder reactor, the concept of functionally graded material was applied for the material combination of Molybdenum/stainless steel/Titanium, in which Titanium and Molybdenum were placed at the inner and outer sides, respectively. Slurry dipping method was employed because of its capability of shape forming and microstructural control. We have hitherto reported the design criteria for the graded layers, preparation of the slurry, and microstructural control of the dip-coated layers. In the present report, the thickness control of the dip-coated layer is described in detail. The thickness of the dip-coated layer depends primarily on the viscosity of the slurry. Nevertheless, for the stable dispersion of the powder in the slurry, which dominates the microstructural homogeneity, an optimum viscosity value is present for the individual slurries. With stable slurries of Ti, Mo, stainless steel powders and their mixtures, the thicknesses of dip-coated layers were controlled in dependence of their viscosities and yield values. For Ti and stainless steel powders and their mixture a PAANa was used as a dispersing agent. A NaHMP was found to be effective for the dispersion of Mo powder and Mo/stainless steel powder mixture. For all slurries tested in the present investigation PVA addition was helpful for the viscosity control. Dip-coating maps have been drawn for the stabilization of the slurries and for the formation of films with a sufficient strength for further manipulation for the slurries with low viscosity (∼10 mPa s). The final film thickness for the low-viscosity slurry with the optimum condition was about 200 μm. The slurries with high viscosities of several hundreds mPa s had a good stability and the yield value was easy to be controlled. The film thickness was able to be adjusted in the size range between several tens and several hundreds μm. The final thickness of the graded layer was determined

  10. Large-scale micromagnetic simulation of Nd-Fe-B sintered magnets with Dy-rich shell structures

    Directory of Open Access Journals (Sweden)

    T. Oikawa

    2016-05-01

    Full Text Available Large-scale micromagnetic simulations have been performed using the energy minimization method on a model with structural features similar to those of Dy grain boundary diffusion (GBD-processed sintered magnets. Coercivity increases as a linear function of the anisotropy field of the Dy-rich shell, which is independent of Dy composition in the core as long as the shell thickness is greater than about 15 nm. This result shows that the Dy contained in the initial sintered magnets prior to the GBD process is not essential for enhancing coercivity. Magnetization reversal patterns indicate that coercivity is strongly influenced by domain wall pinning at the grain boundary. This observation is found to be consistent with the one-dimensional pinning theory.

  11. Thick film heater for sensor application

    International Nuclear Information System (INIS)

    Milewski, J; Borecki, M; Kalenik, J; Król, K

    2014-01-01

    A thick film microheater was elaborated. The microheater is intended for fast heating of small volume samples under measurement in optical based system. Thermal analysis of microheater was carried out using finite element method (FEM) for heat transfer calculation as a function of time and space. A nodal heat transfer function was calculated in classical form including all basics mechanisms of heat exchange – heat conduction, convection and radiation were considered. Work focuses on the influence of some construction parameters (ex. length, thermal conductivity of substrate, substrate thickness) on microheater performance. The results show that application of thin substrate of low thermal conductivity and low thickness for miroheater construction and resistor of optimum dimensions leads to significant power consumption decrease and increase of overall optical measurement system performance.

  12. LOW TEMPERATURE SINTERING OF ALUMINA BIOCERAMIC UNDER NORMAL PRESSURE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Superfine alumina powder with high purity (mean particle size is less than 0. 35μm) were used as main starting material for sintering alumina ceramic. A multiple additive MgO-ZrO2 (Y2O3) was homogeneously added into the batch by the chemical coprecipitation method. Sintering of alumina bioceramic at low tempera ture (<1600C) was achieved resulting in a dense and high strength alumina ceramic with the bending strength up to 382 MPa and an improved fracture toughness. Mechanism that the multiple additives promote the sintering of alumina ceramic is discussed on the base of XRD and SEM analysis.

  13. The sintering behavior of close-packed spheres

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund

    2012-01-01

    The sintering behavior of close-packed spheres is investigated using a numerical model. The investigated systems are the body-centered cubic (bcc), face-centered cubic (fcc) and hexagonal close-packed spheres (hcp). The sintering behavior is found to be ideal, with no grain growth until full dens...... density is reached for all systems. During sintering, the grains change shape from spherical to tetrakaidecahedron, similar to the geometry analyzed by Coble [R.L. Coble, J. Appl. Phys. 32 (1961) 787]....

  14. Modeling sintering of multilayers under influence of gravity

    DEFF Research Database (Denmark)

    Frandsen, Henrik Lund; Olevsky, Eugene; Tadesse Molla, Tesfaye

    2013-01-01

    , which describes the combined effect of sintering and gravity of thin multilayers, is derived and later compared with experimental results. It allows for consideration of both uniaxial and biaxial stress states. The model is based on the Skorohod-Olevsky viscous sintering framework, the classical...... laminate theory and the elastic-viscoelastic correspondence principle. The modeling approach is then applied to illustrate the effect of gravity during sintering of thin layers of cerium gadolinium oxide (CGO), and it is found to be significant. © 2012 The American Ceramic Society....

  15. Low temperature spark plasma sintering of YIG powders

    International Nuclear Information System (INIS)

    Fernandez-Garcia, L.; Suarez, M.; Menendez, J.L.

    2010-01-01

    A transition from a low to a high spin state in the magnetization saturation between 1000 and 1100 o C calcination temperature is observed in YIG powders prepared by oxides mixture. Spark plasma sintering of these powders between 900 and 950 o C leads to dense samples with minimal formation of YFeO 3 , opening the way to co-sintering of YIG with metals or metallic alloys. The optical properties depend on the sintering stage: low (high) density samples show poor (bulk) optical absorption.

  16. Selective laser sintering: A qualitative and objective approach

    Science.gov (United States)

    Kumar, Sanjay

    2003-10-01

    This article presents an overview of selective laser sintering (SLS) work as reported in various journals and proceedings. Selective laser sintering was first done mainly on polymers and nylon to create prototypes for audio-visual help and fit-to-form tests. Gradually it was expanded to include metals and alloys to manufacture functional prototypes and develop rapid tooling. The growth gained momentum with the entry of commercial entities such as DTM Corporation and EOS GmbH Electro Optical Systems. Computational modeling has been used to understand the SLS process, optimize the process parameters, and enhance the efficiency of the sintering machine.

  17. Cleanable sintered metal filters in hot off-gas systems

    International Nuclear Information System (INIS)

    Schurr, G.A.

    1981-01-01

    Filters with sintered metal elements, arranged as tube bundles with backflush air cleaning, are the equivalent of bag filters for high-temperature, harsh environments. They are virtually the only alternative for high-temperature off-gas systems where a renewable, highly efficient particle trap is required. Tests were conducted which show that the sintered metal elements installed in a filter system provide effective powder collection in high-temperature atmospheres over thousands of cleaning cycles. Such a sintered metal filter system is now installed on the experimental defense waste calciner at the Savannah River Laboratory. The experimental results included in this paper were used as the basis for its design

  18. Sintering prevention and phase transformation of FePt nanoparticles

    International Nuclear Information System (INIS)

    Ding, Y.; Majetich, S.A.; Kim, J.; Barmak, K.; Rollins, H.; Sides, P.

    2004-01-01

    Two approaches attempted to overcome FePt nanoparticle sintering during the transformation to the high coercivity L1 0 phase, which currently limits the use of these nanoparticles in data storage media. High-pressure treatment of dilute nanoparticle solutions failed to prevent sintering due to surfactant decomposition above 360 deg. C. By pre-annealing nanoparticle monolayers to decompose the surfactant, and then coating with an immiscible SiO 2 matrix, sintering was prevented with annealing temperatures up to 700 deg. C

  19. Fabrication, Structural Characterization and Uniaxial Tensile Properties of Novel Sintered Multi-Layer Wire Mesh Porous Plates

    Directory of Open Access Journals (Sweden)

    Liuyang Duan

    2018-01-01

    Full Text Available There is an increasing interest in developing porous metals or metallic foams for functional and structural applications. The study of the physical and mechanical properties of porous metals is very important and helpful for their application. In this paper, a novel sintered multilayer wire mesh porous plate material (WMPPs with a thickness of 0.5 mm–3 mm and a porosity of 10–35% was prepared by winding, pressing, rolling, and subsequently vacuum sintering them. The pore size and total size distribution in the as-prepared samples were investigated using the bubble point method. The uniaxial tensile behavior of the WMPPs was investigated in terms of the sintering temperature, porosity, wire diameter, and manufacturing technology. The deformation process and the failure mechanism under the tensile press was also discussed based on the appearance of the fractures (SEM figures. The results indicated that the pore size and total size distribution were closely related to the raw material used and the sintering temperature. For the WMPPs prepared by the wire mesh, the pore structures were inerratic and the vast majority of pore size was less than 10 μm. On the other hand, for the WMPPs that were prepared by wire mesh and powder, the pore structures were irregular and the pore size ranged from 0 μm–50 μm. The experimental data showed that the tensile strength of WMPPs is much higher than any other porous metals or metallic foams. Higher sintering temperatures led to coarser joints between wires and resulted in higher tensile strength. The sintering temperature decreased from 1330 °C to 1130 °C and the tensile strength decreased from 296 MPa to 164 MPa. Lower porosity means that there are more metallurgical joints and metallic frameworks resisting deformation per unit volume. Therefore, lower porosities exhibit higher tensile strength. An increase of porosity from 17.14% to 32.5% led to the decrease of the tensile strength by 90 MPa. The

  20. Monitoring production target thickness

    International Nuclear Information System (INIS)

    Oothoudt, M.A.

    1993-01-01

    Pion and muon production targets at the Clinton P. Anderson Meson Physics Facility consist of rotating graphite wheels. The previous target thickness monitoring Procedure scanned the target across a reduced intensity beam to determine beam center. The fractional loss in current across the centered target gave a measure of target thickness. This procedure, however, required interruption of beam delivery to experiments and frequently indicated a different fractional loss than at normal beam currents. The new monitoring Procedure compares integrated ups and downs toroid current monitor readings. The current monitors are read once per minute and the integral of readings are logged once per eight-hour shift. Changes in the upstream to downstream fractional difference provide a nonintrusive continuous measurement of target thickness under nominal operational conditions. Target scans are now done only when new targets are installed or when unexplained changes in the current monitor data are observed

  1. Sintering equation: determination of its coefficients by experiments - using multiple regression

    International Nuclear Information System (INIS)

    Windelberg, D.

    1999-01-01

    Sintering is a method for volume-compression (or volume-contraction) of powdered or grained material applying high temperature (less than the melting point of the material). Maekipirtti tried to find an equation which describes the process of sintering by its main parameters sintering time, sintering temperature and volume contracting. Such equation is called a sintering equation. It also contains some coefficients which characterise the behaviour of the material during the process of sintering. These coefficients have to be determined by experiments. Here we show that some linear regressions will produce wrong coefficients, but multiple regression results in an useful sintering equation. (orig.)

  2. Improvement of mechanical strength of sintered Mo alloyed steel by optimization of sintering and cold-forging processes with densification

    Science.gov (United States)

    Kamakoshi, Y.; Shohji, I.; Inoue, Y.; Fukuda, S.

    2017-10-01

    Powder metallurgy (P/M) materials have been expected to be spread in automotive industry. Generally, since sintered materials using P/M ones contain many pores and voids, mechanical properties of them are inferior to those of conventional wrought materials. To improve mechanical properties of the sintered materials, densification is effective. The aim of this study is to improve mechanical strength of sintered Mo-alloyed steel by optimizing conditions in sintering and cold-forging processes. Mo-alloyed steel powder was compacted. Then, pre-sintering (PS) using a vacuum sintering furnace was conducted. Subsequently, coldforging (CF) by a backward extrusion method was conducted to the pre-sintered specimen. Moreover, the cold-forged specimen was heat treated by carburizing, tempering and quenching (CQT). Afterwards, mechanical properties were investigated. As a result, it was found that the density of the PS specimen is required to be more than 7.4 Mg/m3 to strengthen the specimen by heat treatment after CF. Furthermore, density and the microstructure of the PS specimen are most important factors to make the high density and strength material by CF. At the CF load of 1200 kN, the maximum density ratio reached approximately 99% by the use of the PS specimen with proper density and microstructure. At the CF load of 900 kN, although density ratio was high like more than 97.8%, transverse rupture strength decreased sharply. Since densification caused high shear stress and stress concentration in the surface layer, microcracks occurred by the damages of inter-particle sintered connection of the surface layer. On the contrary, in case of the CF load of 1200 kN, ultra-densification of the surface layer occurred by a sufficient plastic flow. Such sufficient compressed specimens regenerated the sintered connections by high temperature heat treatment and thus the high strength densified material was obtained. These processes can be applicable to near net shape manufacturing

  3. Fast radiographic systems

    International Nuclear Information System (INIS)

    Domanus, J.C.

    1984-08-01

    Industrial radiography can be performed with shorter exposure times, when instead of X-ray film with lead intensifying screens the radiographic paper with fluorescent screen is used. With paper radiography one can obtain lower material, equipment, and labor costs, shorter exposure and processing times, and easier radiation protection. The speed of the radiographic inspection can also be increased by the use of fluorometallic intensifying screens together with a special brand of X-ray film. Before accepting either of the two fast radiographic systems one must be sure that they can produce radiographs of adequate image quality. Therefore an investigation was performed on that subject using ISO wire IQI's and ASTM penetrameters. The radiographic image quality was tested for aluminium and steel up to 30 mm thick using various brands of radiographic paper and X-ray film with fluorometallic screens and comparing them with fast X-ray films with lead screens. Both systems give satisfactory results. (author)

  4. Sintering-alkaline processing of borosilicate ores of Tajikistan

    International Nuclear Information System (INIS)

    Nazarov, F.A.

    2018-01-01

    The aim of the work is to study the processes of decomposition of boron-containing ore by sintering with NaOH, finding the optimal parameters of the decomposition process, studying the kinetics of processes and developing the technological foundations for ore processing. The processes of borosilicate ore processing were studied by sintering with NaOH. Possible mechanisms of chemical reactions of the process of sintering-alkaline decomposition of boron-containing ore are established, the results of which are substantiated by physicochemical methods of analysis. A principal technological scheme for processing of borosilicate ores by a sintering-alkaline method has been developed. In the first chapter, data on alkaline and caking processes for processing boron-containing and aluminium comprising raw materials are available in the literature. Based on this, the directions of our own research are outlined. The second chapter is devoted to the study of the chemical and mineralogical compositions of borosilicate ores and their concentrates with the help of X-ray phase and chemical analysis methods, the stoichiometric calculation of the formation of aluminum, iron, and boron salts has been carried out, and a thermodynamic analysis of the processes of sintering borosilicate ores with alkali has been considered. The third chapter presents the results of a study of sintering-alkaline method of processing of initial borosilicate ore of the Ak-Arkhar Deposit and its concentrate without calcination and after calcination. The kinetics of sintering of borosilicate ores with sodium hydroxide was studied. The optimal conditions of borosilicate ore sintering before and after the preliminary calcination with alkali were determined. Optimal parameters of the sintering process have been found: sintering temperature 800-8500 deg C, duration of the process - 60 minutes, mass ratio of NaOH to raw materials 2: 1. The conditions for sintering of borosilicate concentrate with alkali have been

  5. In situ Transmission Electron Microscopy of catalyst sintering

    DEFF Research Database (Denmark)

    DeLaRiva, Andrew T.; Hansen, Thomas Willum; Challa, Sivakumar R.

    2013-01-01

    Recent advancements in the field of electron microscopy, such as aberration correctors, have now been integrated into Environmental Transmission Electron Microscopes (TEMs), making it possible to study the behavior of supported metal catalysts under operating conditions at atomic resolution. Here......, we focus on in situ electron microscopy studies of catalysts that shed light on the mechanistic aspects of catalyst sintering. Catalyst sintering is an important mechanism for activity loss, especially for catalysts that operate at elevated temperatures. Literature from the past decade is reviewed...... along with our recent in situ TEM studies on the sintering of Ni/MgAl2O4 catalysts. These results suggest that the rapid loss of catalyst activity in the earliest stages of catalyst sintering could result from Ostwald ripening rather than through particle migration and coalescence. The smallest...

  6. Zone refining of sintered, microwave-derived YBCO superconductors

    International Nuclear Information System (INIS)

    Warrier, K.G.K.; Varma, H.K.; Mani, T.V.; Damodaran, A.D.; Balachandran, U.

    1993-07-01

    Post-sintering treatments such as zone melting under thermal gradient has been conducted on sintered YBCO tape cast films. YBCO precursor powder was derived through decomposition of a mixture of nitrates of cations in a microwave oven for ∼4 min. The resulting powder was characterized and made into thin sheets by tape casting and then sintered at 945 C for 5 h. The sintered tapes were subjected to repeated zone refining operations at relatively high speeds of ∼30 mm/h. A microstructure having uniformly oriented grains in the a-b plane throughout the bulk of the sample was obtained by three repeated zone refining operations. Details of precursor preparation, microwave processing and its advantages, zone refining conditions, and microstructural features are presented in this paper

  7. Efficient Radiation Shielding Through Direct Metal Laser Sintering

    Data.gov (United States)

    National Aeronautics and Space Administration — We have developed a method for efficient component-level radiation shielding that can be printed by direct metal laser sintering (DMLS) from files generated by the...

  8. Effect of increasing lanthanum substitution and the sintering ...

    Indian Academy of Sciences (India)

    Administrator

    University of Hyderabad, P.O. Central University, Hyderabad 500 046, India. MS received 27 ... sintering can cause problems in the stoichiometry of the final product owing to ..... Rambabu greatfully acknowledges the financial support from the ...

  9. Liquid Phase Sintering of Highly Alloyed Stainless Steel

    DEFF Research Database (Denmark)

    Mathiesen, Troels

    1996-01-01

    Liquid phase sintering of stainless steel is usually applied to improve corrosion resistance by obtaining a material without an open pore system. The dense structure normally also give a higher strength when compared to conventional sintered steel. Liquid phase sintrering based on addition...... of boride to AISI 316L type steels have previously been studied, but were found to be sensitive to intergranular corrosion due to formation of intermetallic phases rich in chromium and molybdenum. In order to improve this system further, new investigations have focused on the use of higher alloyed stainless...... steel as base material. The stainless base powders were added different amounts and types of boride and sintered in hydrogen at different temperatures and times in a laboratory furnace. During sintering the outlet gas was analyzed and subsequently related to the obtained microstructure. Thermodynamic...

  10. Microstructure and properties of sintered mullite developed from ...

    Indian Academy of Sciences (India)

    Microstructure and properties of sintered mullite developed from Indian bauxite ... ductivity, high-temperature stability, good chemical inertia, ... refractory applications. Normally .... using sputtered gold coating on the polished surface after.

  11. The behaviour of doped elements in tungsten sintering

    International Nuclear Information System (INIS)

    Scheiner, L.

    1975-01-01

    The lecture deals with the occurrence of bubbles in the sintering of doped tungsten. The doping of tungsten normally takes place by the addition of K, Al and Si compounds. A part of the doping substances disappears with sintering which can easily be proved by chemical analyses. In the process described here, the evaporation is non-destructively observed during sintering with an absorption spectrometer. Temperature, absorption slope and sintering resistance are recorded. The evaluation of the absorption curves gives a diffusion equation. The discussion of the curves resulted so far in that a doped substance compound sets free the single elements of the compound at high temperature. Aluminium and silicon diffuse out. In the case of aluminium, the activation energy can be determined. (GSC/LH) [de

  12. Non-pressurized sintered silicon carbide with titanium carbide reinforcement

    International Nuclear Information System (INIS)

    Adler, J.

    1992-01-01

    A non-pressurized compression of SiC-TiC composite materials can be achieved via liquid phase sintering by the application of oxidic additives. Materials with TiC proportions up to 40% by volume of TiC and densities of 97 to 98% TD were produced at sintering temperatures around 1875 C. With SiC sintered in the liquid phase an increase of toughness at fracture of 80% compared with conventionally non-pressurized sintered SiC was achieved with B/C additive. No further increase could be achieved by the addition of TiC particles. However, the oxidation resistance at 1200 C was worsened. (orig.) [de

  13. Grain-growth law during Stage 1 sintering of materials

    International Nuclear Information System (INIS)

    He Zeming; Ma, J.

    2002-01-01

    This work investigates the grain-growth behaviour of powder compact during Stage 1 sintering (<90{%} theoretical density). It is widely accepted that grain size is an important state variable in the constitutive modelling in material sintering. However, it is noted that all the existing grain-growth laws proposed in the literature do not incorporate the effect of externally applied stress independently. In this work, a grain-growth law with externally applied stress as a variable was proposed. Alumina powders were forge-sintered at different applied stresses to examine the proposed grain-growth relationship. The proposed grain-growth law was then applied to model the grain-growth process on the sinter forging of tool steel. It is shown that the present proposed grain-growth law provides a good description on the experimental results. (author)

  14. Pressureless sintering behavior of injection molded alumina ceramics

    Directory of Open Access Journals (Sweden)

    Liu W.

    2014-01-01

    Full Text Available The pressureless sintering behaviors of two widely used submicron alumina (MgOdoped and undoped with different solid loadings produced by injection molding have been studied systematically. Regardless of the sinterability of different powders depending on their inherent properties, solid loading plays a critical role on the sintering behavior of injection molded alumina, which greatly determines the densification and grain size, and leads to its full densification at low temperatures. As compared to the MgO-doped alumina powder, the undoped specimens exhibit a higher sinterability for its smaller particle size and larger surface area. While full densification could be achieved for MgO-doped powders with only a lower solid loading, due to the fact that MgO addition can reduce the detrimental effect of the large pore space on the pore-boundary separation.

  15. Verification of the Skorohod-Olevsky Viscous Sintering (SOVS) Model

    Energy Technology Data Exchange (ETDEWEB)

    Lester, Brian T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-11-16

    Sintering refers to a manufacturing process through which mechanically pressed bodies of ceramic (and sometimes metal) powders are heated to drive densification thereby removing the inherit porosity of green bodies. As the body densifies through the sintering process, the ensuing material flow leads to macroscopic deformations of the specimen and as such the final configuration differs form the initial. Therefore, as with any manufacturing step, there is substantial interest in understanding and being able to model the sintering process to predict deformation and residual stress. Efforts in this regard have been pursued for face seals, gear wheels, and consumer products like wash-basins. To understand the sintering process, a variety of modeling approaches have been pursued at different scales.

  16. Sintering and electrical properties of strontium-doped lanthanum manganite

    Energy Technology Data Exchange (ETDEWEB)

    Tarrago, Diego Pereira; Sousa, Vania Caldas de [Universidade Federal do Rio Grande do Sul (LABIOMAT/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Biomateriais], Email: dptarrago@gmail.com; Moreno Buriel, Berta; Chinarro Martini, Eva; Jurado Egea, Jose Ramon [Consejo Superior de Investigaciones Cientificas (ICV/CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio; Malfatti, Celia de Fraga [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Pesquisa em Corrosao

    2010-07-01

    Lanthanum strontium manganites (LSM) are potential materials for cathode applications in solid oxide fuel cells (SOFC) due to their good catalytic activity, chemical stability and compatibility with electrolyte materials in high temperatures. The sinterability of single phase La{sub 1-x}Sr{sub x}Mn{sub O3} (x=0.18) perovskite powders and the electrical properties of the resulting samples are analyzed in this study. Using a heating microscope, the powders were pressed and sintered at different pressures and temperatures, resulting in an open porosity of 33.36% when compacted at 125 MPa and sintered at 1200 degree C. Top and cross-section s canning electron microscopy (SEM) micrographs revealed interconnected pores in the sintered body and, hence, a suitable microstructure for the application. The activation energy for conductance was 0.04 eV and the tested LSM bulk started to exhibit adequate electrical properties at about 500 degree C. (author)

  17. Foam glass obtained through high-pressure sintering

    DEFF Research Database (Denmark)

    Østergaard, Martin Bonderup; Petersen, Rasmus Rosenlund; König, Jakob

    2018-01-01

    Foam glasses are usually prepared through a chemical approach, that is, by mixing glass powder with foaming agents, and heating the mixture to a temperature above the softening point (106.6 Pa s) of the glass. The foaming agents release gas, enabling expansion of the sintered glass. Here, we use...... a physical foaming approach to prepare foam glass. First, closed pores filled with inert gases (He, Ar, or N2) are physically introduced into a glass body by sintering cathode ray tube (CRT) panel glass powder at high gas pressure (5‐25 MPa) at 640°C and, then cooled to room temperature. The sintered bodies...... are subjected to a second heat treatment above the glass transition temperature at atmospheric pressure. This heat treatment causes expansion of the pores due to high internal gas pressure. We found that the foaming ability strongly depends on the gas pressure applied during sintering, and on the kinetic...

  18. Plutonium Immobilization Project Binder Burnout and Sintering Studies (Milestone 6.6a)

    International Nuclear Information System (INIS)

    Chandler, G.

    1999-01-01

    The Plutonium Immobilization Team has developed an integrated test program to understand and optimize the controlling variables for the sintering step of the plutonium immobilization process. Sintering is the key process step that controls the product mineralogy. It is expected that the sintering will be the limiting process step that controls the throughput of the production line. The goal of the current sintering test program is to better understand factors that affect the sintering process

  19. Plutonium Immobilization Project Binder Burnout and Sintering Studies (Milestone 6.6a)

    Energy Technology Data Exchange (ETDEWEB)

    Chandler, G.

    1999-10-28

    The Plutonium Immobilization Team has developed an integrated test program to understand and optimize the controlling variables for the sintering step of the plutonium immobilization process. Sintering is the key process step that controls the product minerology. It is expected that the sintering will be the limiting process step that controls the throughput of the production line. The goal of the current sintering test program is to better understand factors that affect the sintering process.

  20. Coating thickness measurement

    International Nuclear Information System (INIS)

    1976-12-01

    The standard specifies measurements of the coating thickness, which make use of beta backscattering and/or x-ray fluorescence. For commonly used combinations of coating material and base material the appropriate measuring ranges and radionuclides to be used are given for continuous as well as for discontinuous measurements

  1. Process for preparing sintered uranium dioxide nuclear fuel

    International Nuclear Information System (INIS)

    Carter, R.E.

    1975-01-01

    Uranium dioxide is prepared for use as fuel in nuclear reactors by sintering it to the desired density at a temperature less than 1300 0 C in a chemically controlled gas atmosphere comprised of at least two gases which in equilibrium provide an oxygen partial pressure sufficient to maintain the uranium dioxide composition at an oxygen/uranium ratio of at least 2.005 at the sintering temperature. 7 Claims, No Drawings

  2. Modeling constrained sintering of bi-layered tubular structures

    DEFF Research Database (Denmark)

    Tadesse Molla, Tesfaye; Kothanda Ramachandran, Dhavanesan; Ni, De Wei

    2015-01-01

    Constrained sintering of tubular bi-layered structures is being used in the development of various technologies. Densification mismatch between the layers making the tubular bi-layer can generate stresses, which may create processing defects. An analytical model is presented to describe the densi...... and thermo-mechanical analysis. Results from the analytical model are found to agree well with finite element simulations as well as measurements from sintering experiment....

  3. Low temperature sintering of fluorapatite glass-ceramics

    Science.gov (United States)

    Denry, Isabelle; Holloway, Julie A.

    2014-01-01

    Fluorapatite glass-ceramics have been shown to be excellent candidates as scaffold materials for bone grafts, however, scaffold production by sintering is hindered by concurrent crystallization of the glass. Our goal was to investigate the effect of Ca/Al ratio on the sintering behavior of Nb-doped fluorapatite-based glasses in the SiO2-Al2O3-P2O5-MgO-Na2O-K2O-CaO-CaF2 system. Glass compositions with Ca/Al ratio of 1 (A), 2 (B), 4 (C) and 19 (D) were prepared by twice melting at 1525°C for 3h. Glasses were either cast as cylindrical ingots or ground into powders. Disc-shaped specimens were prepared by either sectioning from the ingots or powder-compacting in a mold, followed by heat treatment at temperatures ranging between 700 and 1050°C for 1h. The density was measured on both sintered specimens and heat treated discs as controls. The degree of sintering was determined from these measurements. XRD showed that fluorapatite crystallized in all glass-ceramics. A high degree of sintering was achieved at 775°C for glass-ceramic D (98.99±0.04%), and 900°C for glass-ceramic C (91.31±0.10). Glass-ceramics A or B were only partially sintered at 1000°C (63.6±0.8% and 74.1±1.5%, respectively). SEM revealed a unique microstructure of micron-sized spherulitic fluorapatite crystals in glass-ceramics C and D. Increasing the Ca/Al ratio promoted low temperature sintering of fluorapatite glass-ceramics, which are traditionally difficult to sinter. PMID:24252652

  4. Photoacoustic spectroscopy investigation of sintered zinc-tin-oxide ceramics

    Directory of Open Access Journals (Sweden)

    Ivetić Tamara B.

    2007-01-01

    Full Text Available In this paper the changes that occurred in differently activated ZnO-SnO2 and sintered samples were investigated using photoacoustic spectroscopy. ZnO and SnO2 powders, mixed in the molar ratio 2:1, were mechanically activated in a planetary ball mill for 10-160 min. The mixtures were pres­sed and isothermally sintered at 1300°C for two hours. X-ray diffraction analysis of the obtained sintered samples was performed in order to investigate changes of the phase composition and confirmed only the presence of a pure zinc stannate (Zn2SnO4 phase in all the sintered samples as a result of the solid state reaction and reaction sintering between the starting ZnO and SnO2 powders. The microstructure of the sintered sam­ples was examined by scanning electron microscopy and showed that mechanical activation leads to the formation of a structure with reduced particle size which accelerates spinel formation. Grain growth of the spinel phase slows down the densification process and together with the agglomerates formed during mechanical activation causes the appearance of a porous microstructure. The photoacoustic (PA phase and amplitude spectra of the sintered samples were recorded as a function of the chopped frequency of the laser beam used (red laser with a power of 25 mW, λ=632 nm in a thermal-transmission detection configuration. PA experimental data were analyzed using the Rosenzweig-Gersho thermal-piston model, which enabled determination of the thermal diffusivity, ZT (m2s-1, diffusion coefficient of the minority free carriers D (m2s-1 and the optical absorption coefficient (m-1. The detected differences of the measured thermal-electrical properties of the obtained Zn2SnO4 ceramics indicate changes in the material induced by the different preparation procedure of the starting powders before the sintering process.

  5. Critical issues and future directions in sintering science

    International Nuclear Information System (INIS)

    Brook, R.J.; Tuan, W.H.; Xue, L.A.

    1988-01-01

    The quality of available powders and the emphasis on direct microstructural observation have continued to improve the value of sintering studies for the processing of ceramics. Future concerns will relate to mechanisms for the correction of microstructural inhomogeneity so that pressureless processing of composites can be reliably achieved and to more systematic exploitation of dopants (sintering additives). These themes are illustrated using examples from the processing of alumina composites and doped barium titanate compositions

  6. Low temperature sintering of fluorapatite glass-ceramics.

    Science.gov (United States)

    Denry, Isabelle; Holloway, Julie A

    2014-02-01

    Fluorapatite glass-ceramics have been shown to be excellent candidates as scaffold materials for bone grafts, however, scaffold production by sintering is hindered by concurrent crystallization of the glass. Objective, our goal was to investigate the effect of Ca/Al ratio on the sintering behavior of Nb-doped fluorapatite-based glasses in the SiO2-Al2O3-P2O5-MgO-Na2O-K2O-CaO-CaF2 system. Methods, glass compositions with Ca/Al ratio of 1 (A), 2 (B), 4 (C) and 19 (D) were prepared by twice melting at 1525°C for 3h. Glasses were either cast as cylindrical ingots or ground into powders. Disk-shaped specimens were prepared by either sectioning from the ingots or powder-compacting in a mold, followed by heat treatment at temperatures ranging between 700 and 1050°C for 1h. The density was measured on both sintered specimens and heat treated discs as controls. The degree of sintering was determined from these measurements. Results and Significance XRD showed that fluorapatite crystallized in all glass-ceramics. A high degree of sintering was achieved at 775°C for glass-ceramic D (98.99±0.04%), and 900°C for glass-ceramic C (91.31±0.10). Glass-ceramics A or B were only partially sintered at 1000°C (63.6±0.8% and 74.1±1.5%, respectively). SEM revealed a unique microstructure of micron-sized spherulitic fluorapatite crystals in glass-ceramics C and D. Increasing the Ca/Al ratio promoted low temperature sintering of fluorapatite glass-ceramics, which are traditionally difficult to sinter. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  7. Ferritic oxide dispersion strengthened alloys by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Allahar, Kerry N., E-mail: KerryAllahar@boisestate.edu [Materials and Science Engineering Department, Boise State University, 1910 University Blvd., Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd., Idaho Falls, ID 83401 (United States); Burns, Jatuporn [Materials and Science Engineering Department, Boise State University, 1910 University Blvd., Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd., Idaho Falls, ID 83401 (United States); Jaques, Brian [Materials and Science Engineering Department, Boise State University, 1910 University Blvd., Boise, ID 83725 (United States); Wu, Y.Q. [Materials and Science Engineering Department, Boise State University, 1910 University Blvd., Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd., Idaho Falls, ID 83401 (United States); Charit, Indrajit [Department of Chemical and Materials Engineering, University of Idaho, McClure Hall Room 405D, Moscow, ID 83844 (United States); Cole, James [Idaho National Laboratory, Idaho Falls, ID 83401 (United States); Butt, Darryl P. [Materials and Science Engineering Department, Boise State University, 1910 University Blvd., Boise, ID 83725 (United States); Center for Advanced Energy Studies, 995 University Blvd., Idaho Falls, ID 83401 (United States)

    2013-11-15

    Spark plasma sintering (SPS) was used to consolidate a Fe–16Cr–3Al (wt.%) powder that was mechanically alloyed with Y{sub 2}O{sub 3} and Ti powders to produce 0.5 Y{sub 2}O{sub 3} and 0.5 Y{sub 2}O{sub 3}–1Ti powders. The effects of mechanical alloying and sintering conditions on the microstructure, relative density and hardness of the sintered oxide dispersion strengthened (ODS) alloys are presented. Scanning electron microscopy indicated a mixed fine-grain and coarse-grain microstructure that was attributed to recrystallization and grain growth during sintering. Analysis of the transmission electron microscopy (TEM) and atom probe tomography (APT) data identified Y–O and Y–O–Ti nanoclusters. Elemental ratios of these nanoclusters were consistent with that observed in hot-extruded ODS alloys. The influence of Ti was to refine the grains as well as the nanoclusters with there being greater number density and smaller sizes of the Y–O–Ti nanoclusters as compared to the Y–O nanoclusters. This resulted in the Ti-containing samples being harder than the Ti-free alloys. The hardness of the alloys with the Y–O–Ti nanoclusters was insensitive to sintering time while smaller hardness values were associated with longer sintering times for the alloys with the Y–O nanoclusters. Pressures greater than 80 MPa are recommended for improved densification as higher sintering temperatures and longer sintering times at 80 MPa did not improve the relative density beyond 97.5%.

  8. Properties of Mo-alloyed sintered manganese steels

    International Nuclear Information System (INIS)

    Romanski, A.; Cias, A.

    1998-01-01

    Sintered alloy steels are needed for mostly PM structural parts. Powder metallurgy techniques provide a means of fabricating high quality steel parts with tailored mechanical properties. It is now possible to produce sintered steel parts with properties equal to an even superior to those of parts made by more traditional routes. Challenges arise both with the material selection and component fabrication. This work outlines the processing for high performance structural application. (author)

  9. Impact strength of sintered astaloy CrM powders

    International Nuclear Information System (INIS)

    Kazior, J.; Ploszczak, J.; Nykiel, M.; Pieczonka, T.

    2003-01-01

    In this paper results of a series of impact tests on sintered Astaloy CrM powders alloys modified by boron are presented and discussed. Boron in different forms, i.e. as elemental boron powder, boron carbide B 4 C powder or mixture of boron and carbon elemental powders, was used in different weight percentage to activate sintering of Astaloy CrM powder and to increase hardenability, with aim of increasing impact strength in view of structural applications. (author)

  10. Ash chemistry and sintering, verification of the mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Hupa, M.; Skrifvars, B.J. [Aabo Akademi, Turku (Finland)

    1996-12-01

    In this project four sintering mechanisms have been studied, i.e., partial melting with a viscous liquid, partial melting with a non-viscous liquid, chemical reaction sintering and solid state sintering. The work has aimed at improving the understanding of ash sintering mechanisms and quantifying their role in combustion and gasification. The work has been oriented in particular on the understanding of biomass ash behavior. The work has not directly focused on any specific technical application. However, results can also be applied on other fuels such as brown coal, petroleum coke, black liquor and different types of wastes (PDF, RDF, MSW). In one part of study the melting behavior was calculated for ten biomass ashes and compared with lab measurements of sintering tendencies. The comparison showed that the T{sub 15} temperatures, i.e. those temperatures at which the ashes contained 15 % molten phase, correlated fairly well with the temperature at which the sintering measurements detected sintering. This suggests that partial melting can be predicted fairly accurate for some ashes already with the today existing thermodynamic calculation routines. In some cases, however the melting calculations did not correlate with the detected sintering temperatures. In a second part detailed measurements on ash behavior was conducted both in a semi full scale CFB and a lab scale FBC. Ashes and deposits were collected and analyzed in several different ways. These analyses show that the ash chemistry shifts radically when the fuel is shifted. Fuels with silicate based ashes behaved totally different than those with an oxide or salt based ash. The chemistry was also affected by fuel blending. The ultimate goal has been to be able to predict the ash thermal behavior during biomass thermal conversion, using the fuel and ash elemental analyses and a few operational key parameters as the only input data. This goal has not yet today been achieved. (author)

  11. Properties of Bulk Sintered Silver As a Function of Porosity

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, Andrew A [ORNL; Vuono, Daniel J [ORNL; Wang, Hsin [ORNL; Ferber, Mattison K [ORNL; Liang, Zhenxian [ORNL

    2012-06-01

    This report summarizes a study where various properties of bulk-sintered silver were investigated over a range of porosity. This work was conducted within the National Transportation Research Center's Power Device Packaging project that is part of the DOE Vehicle Technologies Advanced Power Electronics and Electric Motors Program. Sintered silver, as an interconnect material in power electronics, inherently has porosity in its produced structure because of the way it is made. Therefore, interest existed in this study to examine if that porosity affected electrical properties, thermal properties, and mechanical properties because any dependencies could affect the intended function (e.g., thermal transfer, mechanical stress relief, etc.) or reliability of that interconnect layer and alter how its performance is modeled. Disks of bulk-sintered silver were fabricated using different starting silver pastes and different sintering conditions to promote different amounts of porosity. Test coupons were harvested out of the disks to measure electrical resistivity and electrical conductivity, thermal conductivity, coefficient of thermal expansion, elastic modulus, Poisson's ratio, and yield stress. The authors fully recognize that the microstructure of processed bulk silver coupons may indeed not be identical to the microstructure produced in thin (20-50 microns) layers of sintered silver. However, measuring these same properties with such a thin actual structure is very difficult, requires very specialized specimen preparation and unique testing instrumentation, is expensive, and has experimental shortfalls of its own, so the authors concluded that the herein measured responses using processed bulk sintered silver coupons would be sufficient to determine acceptable values of those properties. Almost all the investigated properties of bulk sintered silver changed with porosity content within a range of 3-38% porosity. Electrical resistivity, electrical conductivity

  12. Sintered nuclear fuel and method of preparing same

    International Nuclear Information System (INIS)

    Abate-Daga, G.; Amato, I.

    1975-01-01

    A description is given of a method of preparing a nuclear fuel containing a consumable nuclear poison uniformly distributed therein in the form of coated micro-spheres of between 10 and 2,000 microns diameter, consisting in preparing sintered micro-spheres of the consumable poison, covering those micro-spheres with a protective coating and incorporating the coated micro-spheres into uranium dioxide powder, followed by sintering

  13. Realization of hexagonal barium ferrite thick films on Si substrates using a screen printing technique

    International Nuclear Information System (INIS)

    Chen Yajie; Smith, Ian; Geiler, Anton L; Vittoria, Carmine; Harris, Vincent G; Zagorodnii, Volodymyr; Celinski, Zbigniew

    2008-01-01

    Hexagonal barium ferrite thick films (50-200 μm) have been deposited on Si and Al 2 O 3 /Si substrates using a screen printing technique. X-ray diffractometry, scanning electron microscopy and magnetometry were used to characterize and correlate the ferrite films' microstructure and magnetic properties. The experiments indicated that an Al 2 O 3 underlayer was effective in preventing silicon diffusion into the barium ferrite films during a final sintering treatment at temperatures above 1100 deg. C. A two-stage sintering process allowed a reasonable tradeoff between mechanical and magnetic properties. This work reveals the feasibility of fabrication of thick ferrite films on large substrates (up to 25 mm in diameter) for future planar microwave devices compatible with semiconductor integrated circuits processing

  14. NdFeB thick films prepared by tape casting

    International Nuclear Information System (INIS)

    Pawlowski, B.; Schwarzer, S.; Rahmig, A.; Toepfer, J.

    2003-01-01

    NdFeB films of thickness between 100 and 800 μm were prepared by tape casting of a slurry containing 84-95 wt% of commercial NdFeB powder (MQP-B, -Q and -S). After curing the flexible green tapes at 120 deg. C non-porous magnetic films are obtained. The remanence of the films is in the range of 350-450 mT and the coercivity is between 300 and 800 kA/m depending on the type of MQP powder used. The magnetic properties of the films are discussed in relation to film composition and type of magnetic material. For MEMS applications the thick films are magnetized with a multi-pole stripe pattern with 1 mm pole pitch. The induction at the surface of the films was measured with a Hall probe and compared to theoretical calculations. The results indicate that the films are completely magnetized regardless of the film thickness. Tape-casted NdFeB thick films are promising candidates for applications in micro-systems or actuators. Miniaturization of the magnet components is one of the key issues in the development of electromagnetic micro-systems, thus creating a need for replacement of small sintered magnets by magnetic thick film components. Other applications include encoders

  15. SINTERING EFFECTS ON THE DENSIFICATION OF NANOCRYSTALLINE HYDROXYAPATITE

    Directory of Open Access Journals (Sweden)

    M. Amiriyan

    2011-06-01

    Full Text Available The effects of sintering profiles on the densification behaviour of synthesized nanocrystalline hydroxyapatite (HA powder were investigated in terms of phase stability and mechanical properties. A wet chemical precipitation method was successfully employed to synthesize a high purity and single phase HA powder. Green HA compacts were prepared and subjected to sintering in air atmosphere over a temperature range of 700° C to 1300° C. In this study two different holding times were compared, i.e. 1 minute versus the standard 120 minutes. The results revealed that the 1 minute holding time sintering profile was indeed effective in producing a HA body with high density of 98% theoretical when sintered at 1200° C. High mechanical properties such as fracture toughness of 1.41 MPa.m1/2 and hardness of 9.5 GPa were also measured for HA samples sintered under this profile. Additionally, XRD analysis indicated that decomposition of the HA phase during sintering at high temperatures was suppressed.

  16. Manufacture of sintered bricks of high density from beryllium oxide

    International Nuclear Information System (INIS)

    Pointud, R.; Rispal, Ch.; Le Garec, M.

    1959-01-01

    Beryllium oxide bricks of nuclear purity 100 x 100 x 50 and 100 x 100 x 100 mm of very high density (between 2.85 and 3.00) are manufactured by sintering under pressure in graphite moulds at temperatures between 1,750 and 1,850 deg. C, and under a pressure of 150 kg/cm 2 . The physico-chemical state of the saw material is of considerable importance with regard to the success of the sintering operation. In addition, a study of the sintering of a BeO mixture with 3 to 5 per cent of boron introduced in the form of boric acid, boron carbide or elementary boron shows that high densities can only be obtained by sintering under pressure. For technical reasons of manufacture, only the mixture based on boron carbide is used. The sintering is carried out in graphite moulds at 1500 deg. C under 150 kg/cm 2 pressure, and bricks can be obtained with density between 2,85 and 2,90. Laboratory studies and the industrial manufacture of various sinters are described in detail. (author) [fr

  17. Coarsening-densification transition temperature in sintering of uranium dioxide

    International Nuclear Information System (INIS)

    Balakrishna, Palanki; Narasimha Murty, B.; Chakraborthy, K.P.; Jayaraj, R.N.; Ganguly, C.

    2001-01-01

    The concept of coarsening-densification transition temperature (CDTT) has been proposed to explain the experimental observations of the study of sintering undoped uranium dioxide and niobia-doped uranium dioxide powder compacts in argon atmosphere in a laboratory tubular furnace. The general method for deducing CDTT for a given material under the prevailing conditions of sintering and the likely variables that influence the CDTT are described. Though the present work is specific in nature for uranium dioxide sintering in argon atmosphere, the concept of CDTT is fairly general and must be applicable to sintering of any material and has immense potential to offer advantages in designing and/or optimizing the profile of a sintering furnace, in the diagnosis of the fault in the process conditions of sintering, and so on. The problems of viewing the effect of heating rate only in terms of densification are brought out in the light of observing the undesirable phenomena of coring and bloating and causes were identified and remedial measures suggested

  18. Hexagonal OsB2: Sintering, microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Xie, Zhilin; Lugovy, Mykola; Orlovskaya, Nina; Graule, Thomas; Kuebler, Jakob; Mueller, Martin; Gao, Huili; Radovic, Miladin; Cullen, David A.

    2015-01-01

    Highlights: • ReB 2 -type hexagonal OsB 2 powder has been densified by spark plasma sintering. • The sintered OsB 2 contains ∼80 wt.% hexagonal and ∼20 wt.% orthorhombic phases. • The average grain size of the sintered OsB 2 sample was 0.56 ± 0.26 μm. • H = 31 ± 9 GPa and E = 574 ± 112 GPa measured by nanoindentation. - Abstract: The metastable high pressure ReB 2 -type hexagonal OsB 2 bulk ceramics was produced by spark plasma sintering. The phase composition, microstructure, and mechanical behavior of the sintered OsB 2 were studied by X-ray diffraction, optical microscopy, TEM, SEM, EDS, and nanoindentation. The produced ceramics was rather porous and contained a mixture of hexagonal (∼80 wt.%) and orthorhombic (∼20 wt.%) phases as identified by X-ray diffraction and EBSD analysis. Two boron-rich phases, which do not contain Os, were also identified by TEM and SEM/EDS analysis. Nanoindentation measurements yielded a hardness of 31 ± 9 GPa and Young’s modulus of 574 ± 112 GPa, indicating that the material is rather hard and very stiff; however, it is very prone to crack formation and propagation, which is indicative of a very brittle nature of this material. Improvements in the sintering regime are required in order to produce dense, homogeneous and single phase hexagonal OsB 2 bulk ceramics

  19. Uniaxial ratcheting behavior of sintered nanosilver joint for electronic packaging

    International Nuclear Information System (INIS)

    Chen, Gang; Yu, Lin; Mei, Yunhui; Li, Xin; Chen, Xu; Lu, Guo-Quan

    2014-01-01

    Uniaxial ratcheting behavior and the fatigue life of sintered nanosilver joint were investigated at room temperature. All tests were carried out under stress-controlled mode. Force–displacement data were recorded during the entire fatigue lifespan by a non-contact displacement detecting system. Effects of stress amplitude, mean stress, stress rate, and stress ratio on the uniaxial ratcheting behavior of the sintered nanosilver joint were discussed. Stress-life (S–N) curves of the sintered joints were also obtained. The Smith–Watson–Topper (SWT) model, the Gerber model and the modified Goodman model, all of which took effect of mean stress into consideration, were compared for predicting the fatigue life of the sintered joint. Both the ratcheting strain and its rate increased with increasing stress amplitude or mean stress. The increase in stress amplitude and mean stress both reduced the fatigue life of the sintered joint, while the fatigue life prolonged with the increase in stress rate and stress ratio. The modified Goodman model predicted the fatigue life of the sintered joints well

  20. Effect Of Compaction Pressure And Sintering Temperature On The Liquid Phase Sintering Behavior Of Al-Cu-Zn Alloy

    Directory of Open Access Journals (Sweden)

    Lee S.H.

    2015-06-01

    Full Text Available The liquid phase sintering characteristics of Al-Cu-Zn alloy were investigated with respect to various powder metallurgy processing conditions. Powders of each alloying elements were blended to form Al-6Cu-5Zn composition and compacted with pressures of 200, 400, and 600 MPa. The sintering process was performed at various temperatures of 410, 560, and 615°C in N2 gas atmosphere. Density and micro-Vickers hardness measurements were conducted at different processing stages, and transverse rupture strength of sintered materials was examined for each condition, respectively. The microstructure was characterized using optical microscope and scanning electron microscopy. The effect of Zn addition on the liquid phase sintering behavior during P/M process of the Al-Cu-Zn alloy was also discussed in detail.

  1. Damage Behavior of Sintered Fiber Felts

    Directory of Open Access Journals (Sweden)

    Nicolas Lippitz

    2015-04-01

    Full Text Available The reduction of aircraft noise is important due to a rising number of flights and the growth of urban centers close to airports. During landing, a significant part of the noise is generated by flow around the airframe. To reduce that noise porous trailing edges are investigated. Ideally, the porous materials should to be structural materials as well. Therefore, the mechanical properties and damage behavior are of major interest. The aim of this study is to show the change of structure and the damage behavior of sintered fiber felts, which are promising materials for porous trailing edges, under tensile loading using a combination of tensile tests and three dimensional computed tomography scans. By stopping the tensile test after a defined stress or strain and scanning the sample, it is possible to correlate structural changes and the development of damage to certain features in the stress-strain curve and follow the damage process with a high spatial resolution. Finally, the correlation between material structure and mechanical behavior is demonstrated.

  2. Thermal Analysis of Sintered Silver Nanoparticles Film

    Directory of Open Access Journals (Sweden)

    M. Keikhaie

    2014-07-01

    Full Text Available Thin bonded films have many applications in antireflection and reflection coating, insulating and conducting films and semiconductor industries. Thermal conductivity is one of the most important parameter for power packaging since the thermal resistance of the interconnections is directly related to the heat removal capability and thermal management of the power package. The defects in materials play very important role on the effective thermal conductivity. In this paper, finite element method (FEM was utilized to simulate the effect of pores on the effective thermal conductivity of sintered silver nanoparticles film. The simulation results indicate that the effective thermal conductivity of film is different at different directions and would be enhanced when the pore angle is 90. The simulation results will help us to further understand the heat transfer process across highly porous structures and will provide us a powerful guide to design coating with high thermal insulation or conductor property. Because of there is no similar experimental data for this simulation results, this paper is a comparative work among three different models.

  3. Microwave combustion and sintering without isostatic pressure

    International Nuclear Information System (INIS)

    Ebadian, M.A.

    1998-01-01

    In recent years interest has grown rapidly in the application of microwave energy to the processing of ceramics, composites, polymers, and other materials. Advances in the understanding of microwave/materials interactions will facilitate the production of new ceramic materials with superior mechanical properties. One application of particular interest is the use of microwave energy for the mobilization of uranium for subsequent redeposition. Phase III (FY98) will focus on the microwave assisted chemical vapor infiltration tests for mobilization and redeposition of radioactive species in the mixed sludge waste. Uranium hexachloride and uranium (IV) borohydride are volatile compounds for which the chemical vapor infiltration procedure might be developed for the separation of uranium. Microwave heating characterized by an inverse temperature profile within a preformed ceramic matrix will be utilized for CVI using a carrier gas. Matrix deposition is expected to commence from the inside of the sample where the highest temperature is present. The preform matrix materials, which include aluminosilicate based ceramics and silicon carbide based ceramics, are all amenable to extreme volume reduction, densification, and vitrification. Important parameters of microwave sintering such as frequency, power requirement, soaking temperature, and holding time will be investigated to optimize process conditions for the volatilization of uranyl species using a reactive carrier gas in a microwave chamber

  4. An investigation into texturing of high-Tc superconducting ceramics by creep-sintering

    International Nuclear Information System (INIS)

    Regnier, P.; Le Hazif, R.; Chaffron, L.

    1989-01-01

    The possibility of preparing highly textured samples of YBa 2 Cu 3 O 7-x high-Tc ceramics by creep-sintering under an uniaxial stress was investigated in detail. It is shown that the quality of the texture is sharply dependant on: the applied load, the temperature of the sintering dwell, the rate at which this dwell is reached, the exact instant at which the load is applied and the nature of the material in contact with the sample. It is also shown that further annealing without applied stress enhances the texture and considerably increases the grain size. Deformation, which was systematically recorded, occurs within a few minutes after the load is applied and exhibits a stress dependance typical of a viscous flow. Systematic examination by polarized light microscopy has indicated that the texture was homogeneous throughout the whole thickness of all the prepared samples. The resistivity versus temperature curves show that the transition is very sharp and well above 77 K

  5. Low modulus and bioactive Ti/α-TCP/Ti-mesh composite prepared by spark plasma sintering.

    Science.gov (United States)

    Guo, Yu; Tan, Yanni; Liu, Yong; Liu, Shifeng; Zhou, Rui; Tang, Hanchun

    2017-11-01

    A titanium mesh scaffold composite filled with Ti/α-TCP particles was prepared by spark plasma sintering (SPS). The microstructures and interfacial reactions of the composites were investigated by scanning electron microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The compressive strength and elastic modulus were also measured. In vitro bioactivity and biocompatibility was evaluated by using simulated body fluid and cells culture, respectively. After high temperature sintering, Ti oxides, Ti x P y and CaTiO 3 were formed. The formation of Ti oxides and Ti x P y were resulted from the diffusion of O and P elements from α-TCP to Ti. CaTiO 3 was the reaction product of Ti and α-TCP. The composite of 70Ti/α-TCP incorporated with Ti mesh showed a high compressive strength of 589MPa and a low compressive modulus of 30GPa. The bioactivity test showed the formation of a thick apatite layer on the composite and well-spread cells attachment. A good combination of mechanical properties and bioactivity indicated a high potential application of Ti/α-TCP/Ti-mesh composite for orthopedic implants. Copyright © 2017. Published by Elsevier B.V.

  6. Development of sintered composites CaSO{sub 4} doped with Dy and Nd

    Energy Technology Data Exchange (ETDEWEB)

    Chagas, M.A.P.; Parente, L.J.; Souza, D.N. [Universidade Federal de Sergipe (UFS), Aracaju, SE (Brazil). Dept. de Fisica]. E-mails: mchagas@fisica.ufs.br; divanizi@ufs.br

    2007-07-01

    The main of this work was the developing of sintered composites in order to use as thermoluminescent dosimeters using a simple route to preparation, employing high temperature. The composites were prepared with CaSO{sub 4}.2H{sub 2}O doped with Dy{sub 2}O{sub 3} and NdO{sub 3}. Initially CaSO{sub 4}.2H{sub 2}O was dehydrated in oven at 100 deg C by 1h. After the addiction dopants and homogenization of compounds, PVA was incorporated to make easy to compaction of composites. The pellets with 6 mm of diameter and 1 mm thickness were sintered at 900 deg C and 1000 deg C by 6 h. The TL emission showed two peaks when the samples were irradiated with beta source (Sr{sup 90}+Y{sup 90}). In all cases, the calibration curves presented responses proportional to absorbed dose. The results showed that this material have potential to be used in dosimetry. (author)

  7. Coating thickness measuring device

    International Nuclear Information System (INIS)

    Joffe, B.B.; Sawyer, B.E.; Spongr, J.J.

    1984-01-01

    A device especially adapted for measuring the thickness of coatings on small, complexly-shaped parts, such as, for example, electronic connectors, electronic contacts, or the like. The device includes a source of beta radiation and a radiation detector whereby backscatter of the radiation from the coated part can be detected and the thickness of the coating ascertained. The radiation source and detector are positioned in overlying relationship to the coated part and a microscope is provided to accurately position the device with respect to the part. Means are provided to control the rate of descent of the radiation source and radiation detector from its suspended position to its operating position and the resulting impact it makes with the coated part to thereby promote uniformity of readings from operator to operator, and also to avoid excessive impact with the part, thereby improving accuracy of measurement and eliminating damage to the parts

  8. Thick melanoma in Tuscany.

    Science.gov (United States)

    Chiarugi, Alessandra; Nardini, Paolo; Borgognoni, Lorenzo; Brandani, Paola; Gerlini, Gianni; Rubegni, Pietro; Lamberti, Arianna; Salvini, Camilla; Lo Scocco, Giovanni; Cecchi, Roberto; Sirna, Riccardo; Lorenzi, Stefano; Gattai, Riccardo; Battistini, Silvio; Crocetti, Emanuele

    2017-03-14

    The epidemiologic trends of cutaneous melanoma are similar in several countries with a Western-type life style, where there is a progressive increasing incidence and a low but not decreasing mor- tality, or somewhere an increase too, especially in the older age groups. Also in Tuscany there is a steady rise in incidence with prevalence of in situ and invasive thin melanomas, with also an increase of thick melanomas. It is necessary to reduce the frequency of thick melanomas to reduce specific mortality. The objective of the current survey has been to compare, in the Tuscany population, by a case- case study, thin and thick melanoma cases, trying to find out those personal and tumour characteristics which may help to customize preventive interventions. RESULTS The results confirmed the age and the lower edu- cation level are associated with a later detection. The habit to perform skin self-examination is resulted protec- tive forward thick melanoma and also the diagnosis by a doctor. The elements emerging from the survey allow to hypothesize a group of subjects resulting at higher risk for a late diagnosis, aged over 50 and carrier of a fewer constitutional and environmental risk factors: few total and few atypical nevi, and lower sun exposure and burning. It is assumable that a part of people did not be reached from messages of prevention because does not recognize oneself in the categories of people at risk for skin cancers described in educational cam- paigns. If we want to obtain better results on diagnosis of skin melanoma we have to think a new strategy. At least to think over the educational messages discriminating people more at risk of incidence of melanoma from people more at risk to die from melanoma, and to renewed active involvement of the Gen- eral Practitioners .

  9. Thick brane solutions

    International Nuclear Information System (INIS)

    Dzhunushaliev, Vladimir; Minamitsuji, Masato; Folomeev, Vladimir

    2010-01-01

    This paper gives a comprehensive review on thick brane solutions and related topics. Such models have attracted much attention from many aspects since the birth of the brane world scenario. In many works, it has been usually assumed that a brane is an infinitely thin object; however, in more general situations, one can no longer assume this. It is also widely considered that more fundamental theories such as string theory would have a minimal length scale. Many multidimensional field theories coupled to gravitation have exact solutions of gravitating topological defects, which can represent our brane world. The inclusion of brane thickness can realize a variety of possible brane world models. Given our understanding, the known solutions can be classified into topologically non-trivial solutions and trivial ones. The former class contains solutions of a single scalar (domain walls), multi-scalar, gauge-Higgs (vortices), Weyl gravity and so on. As an example of the latter class, we consider solutions of two interacting scalar fields. Approaches to obtain cosmological equations in the thick brane world are reviewed. Solutions with spatially extended branes (S-branes) and those with an extra time-like direction are also discussed.

  10. Recent Advances and Research Status in Energy Conservation of Iron Ore Sintering in China

    Science.gov (United States)

    Wang, Yao-Zu; Zhang, Jian-Liang; Liu, Zheng-Jian; Du, Cheng-Bo

    2017-11-01

    For the ferrous burden of blast furnaces in China, sinter generally accounts for more than 70% and the sintering process accounts for approximately 6-10% of the total energy consumption of the iron and steel enterprise. Therefore, saving energy during the sintering process is important to reduce the energy consumption in the iron and steel industry. This paper aims to illustrate recent advances and the research status of energy conservation of iron ore sintering in China. It focuses on the development and application of energy-saving technologies such as the composite agglomeration process, sintering with high-proportion flue gas recirculation sintering, recovery of sensible heat from the sinter cooling process, homogeneous deep-bed sintering technology, and comprehensive treatment technology of leakage of sintering. Moreover, some suggestions for the future development of energy-saving technologies are put forward.

  11. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Science.gov (United States)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB.

  12. Structure and properties of nano-hydroxypatite scaffolds for bone tissue engineering with a selective laser sintering system

    Energy Technology Data Exchange (ETDEWEB)

    Shuai Cijun; Gao Chengde; Nie Yi; Hu Huanlong; Zhou Ying [Key Laboratory of Modern Complex Equipment Design and Extreme Manufacturing, Central South University, Ministry of Education, Changsha, 410083 (China); Peng Shuping, E-mail: shuping@csu.edu.cn [Cancer Research Institute, Central South University, Changsha, 410078 (China)

    2011-07-15

    In this study, nano-hydroxypatite (n-HAP) bone scaffolds are prepared by a homemade selective laser sintering (SLS) system based on rapid prototyping (RP) technology. The SLS system consists of a precise three-axis motion platform and a laser with its optical focusing device. The implementation of arbitrary complex movements based on the non-uniform rational B-Spline (NURBS) theory is realized in this system. The effects of the sintering processing parameters on the microstructure of n-HAP are tested with x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The particles of n-HAP grow gradually and tend to become spherical-like from the initial needle-like shape, but still maintain a nanoscale structure at scanning speeds between 200 and 300 mm min{sup -1} when the laser power is 50 W, the light spot diameter 4 mm, and the layer thickness 0.3 mm. In addition, these changes do not result in decomposition of the n-HAP during the sintering process. The results suggest that the newly developed n-HAP scaffolds have the potential to serve as an excellent substrate in bone tissue engineering.

  13. Microstructure and properties of TiC-high manganese steel cermet prepared by different sintering processes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhi; Lin, Tao, E-mail: lintao@ustb.edu.cn; He, Xinbo; Shao, Huiping; Zheng, Jianshu; Qu, Xuanhui

    2015-11-25

    In the paper, the TiC −50 wt.% high manganese steel cermet was made with different sintering processes including vacuum sintering, hot pressing, microwave sintering and spark plasma sintering (SPS). The microstructure, porosity and fracture morphology of the samples were analyzed with scanning electron microscopy (SEM). Phase analysis was carried out using X-ray diffraction (XRD). The density, hardness, transverse rupture strength (TRS) and wear resistance were investigated for the effect of the sintering processes. The results showed that the core–shell structure was not clearly observed for the TiC particles in microstructures and the high manganese steel matrix is BCC structure. Hot pressing, microwave sintering and SPS are useful processes for densification of the cermet. Nearly full density and higher hardness can be reached by these three processes at a lower sintering temperature and in a shorter sintering time. However, higher TRS can be reached by means of alloying completely in a longer sintering time, for example vacuum sintering. Pre-sintering in a long sintering time at a lower sintering temperature is also useful for improving the TRS. Finally, vacuum sintering is an effective process for producing this composite with the lowest cost in the mass production. - Highlights: • TiC-high manganese steel cermets were prepared by four sintering processes. • The core–shell structure was not clearly observed for the TiC particles in microstructures. • Th high manganese steel matrix is BCC structure instead of FCC structure. • Pre-sintering before microwave sintering is also useful for improving the TRS. • Vacuum sintering can be effective way for prepare this cermet in mass production.

  14. Dry Sintered Metal Coating of Halloysite Nanotubes

    Directory of Open Access Journals (Sweden)

    James C. Nicholson

    2016-09-01

    Full Text Available Halloysite nanotubes (HNTs are a naturally-occurring aluminosilicate whose dimensions measure microns in length and tens of nanometers in diameter. Bonding defects between the alumina and silica lead to net negative and positive charges on the exterior and interior lumen, respectively. HNTs have been shown to enhance the material properties of polymer matrices and enable the sustained release of loaded chemicals, drugs, and growth factors. Due to the net charges, these nanotubes can also be readily coated in layered-depositions using the HNT exterior lumen’s net negative charge as the basis for assembly. These coatings are primarily done through wet chemical processes, the majority of which are limited in their use of desired chemicals, due to the polarity of the halloysite. Furthermore, this restriction in the type of chemicals used often requires the use of more toxic chemicals in place of greener options, and typically necessitates the use of a significantly longer chemical process to achieve the desired coating. In this study, we show that HNTs can be coated with metal acetylacetonates—compounds primarily employed in the synthesis of nanoparticles, as metal catalysts, and as NMR shift reagents—through a dry sintering process. This method was capable of thermally decaying the metal acetylacetonate, resulting in a free positively-charged metal ion that readily bonded to the negatively-charged HNT exterior, resulting in metallic coatings forming on the HNT surface. Our coating method may enable greater deposition of coated material onto these nanotubes as required for a desired application. Furthermore, the use of chemical processes using toxic chemicals is not required, thus eliminating exposure to toxic chemicals and costs associated with the disposal of the resultant chemical waste.

  15. Fast reactors

    International Nuclear Information System (INIS)

    Vasile, A.

    2001-01-01

    Fast reactors have capacities to spare uranium natural resources by their breeding property and to propose solutions to the management of radioactive wastes by limiting the inventory of heavy nuclei. This article highlights the role that fast reactors could play for reducing the radiotoxicity of wastes. The conversion of 238 U into 239 Pu by neutron capture is more efficient in fast reactors than in light water reactors. In fast reactors multi-recycling of U + Pu leads to fissioning up to 95% of the initial fuel ( 238 U + 235 U). 2 strategies have been studied to burn actinides: - the multi-recycling of heavy nuclei is made inside the fuel element (homogeneous option); - the unique recycling is made in special irradiation targets placed inside the core or at its surroundings (heterogeneous option). Simulations have shown that, for the same amount of energy produced (400 TWhe), the mass of transuranium elements (Pu + Np + Am + Cm) sent to waste disposal is 60,9 Kg in the homogeneous option and 204.4 Kg in the heterogeneous option. Experimental programs are carried out in Phenix and BOR60 reactors in order to study the feasibility of such strategies. (A.C.)

  16. Fast ejendom

    DEFF Research Database (Denmark)

    Pagh, Peter

    Bogen omfatter en gennemgang af lovgivning, praksis og teori vedrørende køb af fast ejendom og offentligretlig og privatretlig regulering. Bogen belyser bl.a. de privatretlige emner: købers misligholdelsesbeføjelser, servitutter, naboret, hævd og erstatningsansvar for miljøskader samt den...

  17. Final Report on Initial Samples Supplied by LLNL for Task 3.3 Binder Burnout and Sintering Schedule Optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Walls, P

    1999-01-04

    Sixteen of the twenty-one samples have been investigated using the scanning laser dilatometer. This includes all three types of samples with different preparation routes and organic content. Cracks were observed in all samples, even those only heated to 300 C. It was concluded that the cracking was occurring in the early part of the heat treatment before the samples reached 300 C. Increase in the rate of dilation of the samples occurred above 170 C which coincided with the decomposition of the binder/wax additives as determined by differential thermal analysis. A comparison was made with SYNROC C material (Powder Run 143), samples of which had been CIPed and green machined to a similar diameter and thickness as the 089mm SRTC pucks. These samples contained neither binder nor other organic processing aids and had been kept in the same desiccator as the SRTC samples. The CIPed Synroc C samples sintered to high density with zero cracks. As the cracks made up only a small contribution to the change in diameter of the sample compared to the sintering shrinkage, useful information could still be gained from the runs. The sintering curves showed that there was much greater shrinkage of the Type III samples containing only the 5% PEG binder compared to the Type I which contained polyolefin wax as processing aid. Slight changes in gradient of the sintering curve were observed, however, due to the masking effect of the cracking, full analysis of the sintering kinetics cannot be conducted. Even heating the samples to 300 C at 1.0 or 0.5 C/min could not prevent crack formation. This indicated that heating rate was not the critical parameter causing cracking of the samples. Sectioning of green bodies revealed the inhomogeneous nature of the binder/lubricant distribution in the samples. Increased homogeneity would reduce the amount of binder/lubricant required, which should in turn, reduce the degree of cracking observed during heating to the binder burnout temperature. A

  18. Designing a Tool System for Lowering Friction during the Ejection of In-Die Sintered Micro Gears

    Directory of Open Access Journals (Sweden)

    Emanuele Cannella

    2017-07-01

    Full Text Available The continuous improvements in micro-forging technologies generally involve process, material, and tool design. The field assisted sintering technique (FAST is a process that makes possible the manufacture of near-net-shape components in a closed-die setup. However, the final part quality is affected by the influence of friction during the ejection phase, caused by radial expansion of the compacted and sintered powder. This paper presents the development of a pre-stressed tool system for the manufacture of micro gears made of aluminum. By using the hot isostatic pressing (HIP sintering process and different combinations of process parameters, the designed tool system was compared to a similar tool system designed without a pre-stressing strategy. The comparison between the two tool systems was based on the ejection force and part fidelity. The ejection force was measured during the tests, while the part fidelity was documented using an optical microscope and computed tomography in order to obtain a multi-scale characterization. The results showed that the use of pre-stress reduced the porosity in the gear by 40% and improved the dimensional fidelity by more than 75% compared to gears produced without pre-stress.

  19. The effects of applied current on one-dimensional interdiffusion between copper and nickel in spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Rudinsky, S.; Gauvin, R.; Brochu, M., E-mail: mathieu.brochu@mcgill.ca [Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, Quebec H3A 0C5 (Canada)

    2014-10-21

    Spark plasma sintering (SPS) is a powder metallurgy technique that employs the use of fast sintering kinetics to produce final consolidated components in a matter of minutes. In order to use blended powders in SPS to obtain fully alloyed parts, diffusion during sintering must be understood. An investigation into the effects of current on the diffusion of copper and nickel was performed using SPS. Bulk specimens were used to generate diffusion couples in SPS in alternating orientations with respect to the direction of the current. Control samples were produced using a horizontal insertion vacuum furnace. Experiments were performed at temperatures between 850°C and 1000°C for 3 h. Concentration profiles were obtained by the use of both energy-dispersive spectroscopy and a Monte Carlo simulated correction curve. Diffusion coefficients and activation energies were calculated for samples produced by SPS and annealing without current. It was shown that, at temperatures near 0.9 T{sub m}, the application of current in SPS inhibits diffusion between copper and nickel due to the re-orientation of electrons caused by the loss of ferromagnetism in nickel. Activation energy for diffusion is, however, decreased due to the temperature gradients arising from the difference in resistivity between the two species.

  20. Investigation of Top/bottom Electrode and Diffusion Barrier Layer for PZT thick film MEMS Sensors

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Hindrichsen, Christian Carstensen; Lou-Møller, R.

    2007-01-01

    In this work screen printed piezoelectric Ferroperm PZ26 lead zirconate titanate (PZT) thick film is used for two MEMS devices. A test structure is used to investigate several aspects regarding bottom and top electrodes. 450 nm ZrO2 thin film is found to be an insufficient diffusion barrier layer...... for thick film PZT sintered at 850degC. E-beam evaporated Al and Pt is patterned on PZT with a lift-off process with a line width down to 3 mum. The roughness of the PZT is found to have a strong influence on the conductance of the top electrode....

  1. Screen printed PZT/PZT thick film bimorph MEMS cantilever device for vibration energy harvesting

    DEFF Research Database (Denmark)

    Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian

    2012-01-01

    We present a microelectromechanical system (MEMS) based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. Most piezoelectric energy harvesting devices use a cantilever beam of a non piezoelectric material as support beneath or in-between the piezoelectric...... elements. We show experimental results from two types PZT/PZT harvesting devices, one where the Pb(ZrxTi1−x)O3 (PZT) thick films are high pressure treated during the fabrication and the other where the treatment is omitted. We find that with the high pressure treatment prior to PZT sintering, the films...

  2. Elaboration of silicon carbides nano particles (SiC): from the powder synthesis to the sintered ceramic

    International Nuclear Information System (INIS)

    Reau, A.

    2008-01-01

    Materials for the reactor cores of the fourth generation will need materials supporting high temperatures with fast neutrons flux. SiC 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 f /SiC composite development and to study the influence of the fabrication parameters. (A.L.B.)

  3. Testing plutonium fuel assembly production for fast-neutron reactors

    International Nuclear Information System (INIS)

    Nougues, B.; Benhamou, A.; Bertothy, G.; Lepetit, H.

    1975-01-01

    The main characteristics of plutonium fuel elements for fast breeder reactors justify specific test procedures and special techniques. The specific tests relating to the Pu content consist of Pu enrichment and distribution tests, determination of the O/M ratio and external contamination tests. The specific tests performed on fuel configuration are: testing of sintered pellet diameter, testing of pin welding and checking of internal assmbly [fr

  4. Study of automatic boat loading unit and horizontal sintering process of uranium dioxide pellet

    International Nuclear Information System (INIS)

    He Zhongjing; Chen Yu; Yao Dengfeng; Wang Youliang; Shu Binhua; Wu Genjiu

    2014-01-01

    Sintering process is a key process for the manufacture of nuclear fuel UO_2 pellet. In our factory, the continuous high temperature sintering furnace is used for sintering process. During the sintering of green pellets, the furnace, the boat and the accumulation way can influence the quality of the final product. In this text, on the basis of early process research, The automatic loading boat Unit and horizontal sintering process is studied successively. The results show that the physical and chemical properties of the products manufactured by automatic loading boat unit and horizontal sintering process can meet the technique requirements completely, and this system is reliable and continuous. (authors)

  5. Increased endometrial thickness in women with hypertension.

    Science.gov (United States)

    Bornstein, J; Auslender, R; Goldstein, S; Kohan, R; Stolar, Z; Abramovici, H

    2000-09-01

    We noticed an increase in endometrial thickness in women with hypertension who were treated with a combination of medications, including beta-blockers. The purpose of this study was to examine whether the endometrium of hypertensive women is thicker than that of healthy women and to determine whether endometrial thickening in hypertensive women is directly related to the antihypertensive beta-blocker treatment. We compared 3 groups of postmenopausal patients as follows: (1) women with a history of essential hypertension treated with a combination of medications, including beta-blockers; (2) women with a history of hypertension treated with a combination of medications that did not include beta-blockers; and (3) healthy women without hypertension. All patients were interviewed and examined, blood tests were performed, and endometrial thickness in the anterior-posterior diameter was measured by vaginal ultrasonography. Among the exclusion criteria were diabetes or an abnormal fasting blood glucose level, obesity, hormonal medication or replacement hormonal therapy during the previous 6 months, and a history of hormonal disturbances, infertility, or polycystic ovary syndrome. Of 45 hypertensive women enrolled in the study, 22 were treated with a beta-blocker combination medication and 23 were treated with other antihypertensive medications. They were compared with 25 healthy women. There was no statistically significant difference in endometrial thickness between women treated with medications, including beta-blockers, and those who were treated with other hypotensive agents. Twenty percent of women with hypertension and none of the healthy women had endometrium >5 mm thick (P infinity). Twenty percent of hypertensive postmenopausal women were found to have increased endometrial thickness. However, we were unable to substantiate an association between the type of treatment administered, whether beta-blockers were included, and the increase in endometrial thickness.

  6. Effect of Power Characteristics on the Densification of Sintered Alumina

    International Nuclear Information System (INIS)

    Al-Sarraj, Z.S.A.; Noor, S.S.

    2011-01-01

    The effect of particle size distribution, soaking time and sintering temperatures on the densification behaviors of α-Al 2 O 3 was investigated. Two different average particle sizes of 36 and 45μ were examined as a variable to analyze the difference in density, radial and axial shrinkage, densification, and microstructure developments. Conventional powder technology route was used to prepare disc-shaped green pellets sintered at 1200-1600 0 C for different periods. Density measurements for both green and sintered compacts allow for the refinement of processing parameters to obtain dense sintered bodies. Compacts with particle size of 36 μm were noticed to attain higher relative densities as compared with those of 45μm. Densification parameter (ΔP) calculations clearly reveals the presence of definite temperatures and times in which limited densification retardation occurred, which permits the suggesting of suitable sintering schemes for this material. Scanning electron micrographs analysis revealed a pore structure assist the observed behaviours for the different schemes. (author)

  7. An investigation on preparation of CIGS targets by sintering process

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Ning, E-mail: zhn98@126.co [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Zhuang Daming; Zhang Gong [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2010-01-15

    Pressureless sintering process was used to fabricate CIGS targets with Cu{sub 2}Se, In{sub 2}Se{sub 3}, and Ga{sub 2}Se{sub 3} as raw powders mixed according to the stoichiometry of CuIn{sub 0.72}Ga{sub 0.28}Se{sub 2} (CIGS). The results showed that only CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} phase can be detected in the sintered targets. The pores in sintered specimen become smaller and distribute more homogeneously under the conditions of finer powders and higher cold pressure. Both mass loss caused by the formation of volatile phase relating to Ga and volume expansion occur during the sintering process, which result in the decrease of density. The tendency of anti-densification becomes stronger under the conditions of coarser powders and higher cold pressure. The sintering process and causes for anti-densification were discussed. Finally, a hot pressing process was carried out, which was proved to be fairly effective to increase the density of CIGS target. The fabricated target can be used for magnetron-sputtering deposition of CIGS absorbers.

  8. Assessment of polyphase sintered iron-cobalt-iron boride cermets

    International Nuclear Information System (INIS)

    Nowacki, J.; Pieczonka, T.

    2004-01-01

    Sintering of iron, cobalt and boron powders has been analysed. As a result iron-iron boride, Fe-Fe 2 B and iron/cobalt boride with a slight admixture of molybdenum, Fe - Co - (FeMoCo) 2 B cermets have been produced. Iron was introduced to the mixture as the Astalloy Mo Hoeganaes grade powder. Elemental amorphous boron powder was used, and formation of borides occurred both during heating and isothermal sintering periods causing dimensional changes of the sintered body. Dilatometry was chosen to control basic phenomena taking place during multiphase sintering of investigated systems. The microstructure and phase constituents of sintered compacts were controlled as well. The cermets produced were substituted to: metallographic tests, X-ray analysis, measurements of hardness and of microhardness, and of wear in the process of sliding dry friction. Cermets are made up of two phases; hard grains of iron - cobalt boride, (FeCo) 2 B (1800 HV) constituting the reinforcement and a relatively soft and plastic eutectic mixture Fe 2 B - Co (400-500 HV) constituting the matrix. (author)

  9. Sintered nuclear fuel compact and method for its production

    International Nuclear Information System (INIS)

    Peehs, M.; Dorr, W.

    1988-01-01

    This patent describes a method of producing a sintered nuclear fuel compact with which reactivity losses in a nuclear reactor having long fuel element cycles are avoided, which comprises, forming a compact of a mixture of powders containing at least one nuclear fuel oxide selected from the group consisting of UO/sub 2/, PuO/sub 2/, ThO/sub 2/, mixed oxide (U, Pu)O/sub 2/ and mixed oxide (U, Th)O/sub 2/, at least one neutron poison selected from the group consisting of UB/sub x/, where x=2; 4 and/or 12 and B/sub 4/C, and sintering the compact of the mixture of powders so that the neutron piston is embedded in a sintered matrix of the nuclear fuel oxide at a treatment temperature in a range from 1000 0 C to 1400 0 C in an oxidizing sintering atmosphere, and then heat treating the sintered compact in a reducing gas atmosphere

  10. FDTD simulation of microwave sintering of ceramics in multimode cavities

    Energy Technology Data Exchange (ETDEWEB)

    Iskander, M.F.; Smith, R.L.; Andrade, A.O.M.; Walsh, L.M. (Univ. of Utah, Salt Lake City, UT (United States). Dept. of Electrical Engineering); Kimrey, H. Jr. (Oak Ridge National Lab., TN (United States))

    1994-05-01

    At present, various aspects of the sintering process such as preparation of sample sizes and shapes, types of insulations, and the desirability of including a process stimulus such as SiC rods are considered forms of art and highly dependent on human expertise. The simulation of realistic sintering experiments in a multimode cavity may provide an improved understanding of critical parameters involved and allow for the development of guidelines towards the optimization of the sintering process. In this paper, the authors utilize the FDTD technique to model various geometrical arrangements and material compatibility aspects in multimode microwave cavities and to simulate realistic sintering experiments. The FDTD procedure starts with the simulation of a field distribution in multimode microwave cavities that resembles a set of measured data using liquid crystal sheets. Also included in the simulation is the waveguide feed as well as a ceramic loading plate placed at the base of the cavity. The FDTD simulation thus provides realistic representation of a typical sintering experiment. Aspects that have been successfully simulated include the effects of various types of insulation, the role of SiC rods on the uniformity of the resulting microwave fields, and the possible shielding effects that may result from excessive use of SiC. These results as well as others showing the electromagnetic fields and power-deposition patterns in multiple ceramic samples are presented.

  11. Low sintering temperature glass waste forms for sequestering radioactive iodine

    Science.gov (United States)

    Nenoff, Tina M.; Krumhansl, James L.; Garino, Terry J.; Ockwig, Nathan W.

    2012-09-11

    Materials and methods of making low-sintering-temperature glass waste forms that sequester radioactive iodine in a strong and durable structure. First, the iodine is captured by an adsorbant, which forms an iodine-loaded material, e.g., AgI, AgI-zeolite, AgI-mordenite, Ag-silica aerogel, ZnI.sub.2, CuI, or Bi.sub.5O.sub.7I. Next, particles of the iodine-loaded material are mixed with powdered frits of low-sintering-temperature glasses (comprising various oxides of Si, B, Bi, Pb, and Zn), and then sintered at a relatively low temperature, ranging from 425.degree. C. to 550.degree. C. The sintering converts the mixed powders into a solid block of a glassy waste form, having low iodine leaching rates. The vitrified glassy waste form can contain as much as 60 wt % AgI. A preferred glass, having a sintering temperature of 500.degree. C. (below the silver iodide sublimation temperature of 500.degree. C.) was identified that contains oxides of boron, bismuth, and zinc, while containing essentially no lead or silicon.

  12. Full reflector thickness and isolation thickness on neutron transport

    International Nuclear Information System (INIS)

    Sakai, Tomohiro; Naito, Yoshitaka; Komuro, Yuichi.

    1988-08-01

    A method to determine ''full reflector thickness'' and ''isolation thickness'', which is utilized for criticality safety evaluation on nuclear fuel facilities, was proposed in this paper. Firstly, a calculation was tryed to obtain the two kinds of thicknesses from the result of criticality calculations for a specific case. Then, two simple equations which calculates the two kinds of thicknesses were made from the relation between reflector (or isolator) thickness and k eff , and one-group diffusion theory. Finally, we proposed a new method to determine the thicknesses. From the method we proposed, ''full reflector thickness'' and ''isolation thickness'' can be obtain using the equations and migration length of the reflector (or isolator) and infinite and effective multiplication factor of the fuel. (author)

  13. Flame-sintered ceramic exoelectron dosimeter samples

    International Nuclear Information System (INIS)

    Petel, M.; Holzapfel, G.

    1979-01-01

    New techniques for the preparation of integrating solid state dosimeters, particularly exoelectron dosimeters, have been initiated. The procedure consists in melting the powdered dosimeter materials in a hot, fast gas stream and depositing the ceramic layer. The gas stream is generated either through a chemical flame or by an electrical arc plasma. Results will be reported on the system Al 2 O 3 /stainless steel as a first step to a usable exoelectron dosimeter

  14. Granulation of coke breeze fine for using in the sintering process

    Directory of Open Access Journals (Sweden)

    Mohamed F.M.

    2010-01-01

    Full Text Available Coke breeze is the main fuel used in the sintering process. The value of -3+1 mm. represents the most favorable particle size for coke breeze in the sintering process. About 20% of total coke fines (-0.5 mm are produced during different steps of preparation. Introducing these fines during the sintering process proves to be very harmful for different operating parameters. Thus ,this study aims at investigating the production of granules resulting from these fines using molasses as organic binder and its application in sintering of an iron ore. The results showed that the granules having the highest mechanical properties were obtained with 14.5 wt % molasses addition. The sintering experiments were performed by using coke breeze in different shapes (-3+1 mm in size, coke breeze without sieving and coke breeze granules -3+1 mm. The reduction experiments, microscopic structure and X-ray analysis for the produced sinter were carried out. The results revealed that, all sinter properties (such as shatter test, productivity of sinter machine and blast furnace, reduction time and chemical composition for produced sinter by using coke breeze with size -3+1 mm and coke breeze granules were almost the same. The iron ore sinter which was produced by using coke breeze without sieving yielded low productivity for both sinter machine and blast furnace. Furthermore, using coke breeze without sieving in sintering of an iron ore decreases the vertical velocity of sinter machine and increases the reduction time.

  15. Residual stresses in a co-sintered SOC half-cell during post-sintering cooling

    DEFF Research Database (Denmark)

    Charlas, Benoit; Chatzichristodoulou, Christodoulos; Brodersen, Karen

    2014-01-01

    .e. the reference temperature (Tref) or the strain difference based on the curvature. This approximation gives good results for bilayers with a defined cooling temperature profile, where the curvature of the bilayer defines a unique balance between the two unknown residual stress states in the two layers......Due to the thermal expansion mismatch between the layers of a Solid Oxide Cell, residual stresses (thermal stresses) develop during the cooling after sintering. Residual stresses can induce cell curvature for asymmetric cells but more importantly they also result in more fragile cells. Depending...... on the loading conditions, the additional stress needed to break the cells can indeed be smaller due to the initial thermo-mechanical stress state. The residual stresses can for a bilayer cell be approximated by estimating the temperature at which elastic stresses start to build up during the cooling, i...

  16. Direct laser sintered WC-10Co/Cu nanocomposites

    Science.gov (United States)

    Gu, Dongdong; Shen, Yifu

    2008-04-01

    In the present work, the direct metal laser sintering (DMLS) process was used to prepare the WC-Co/Cu nanocomposites in bulk form. The WC reinforcing nanoparticles were added in the form of WC-10 wt.% Co composite powder. The microstructural features and mechanical properties of the laser-sintered sample were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX), and nanoindentation tester. It showed that the original nanometric nature of the WC reinforcing particulates was well retained without appreciable grain growth after laser processing. A homogeneous distribution of the WC reinforcing nanoparticles with a coherent particulate/matrix interfacial bonding was obtained in the laser-sintered structure. The 94.3% dense nanocomposites have a dynamic nanohardness of 3.47 GPa and a reduced elastic modulus of 613.42 GPa.

  17. Direct laser sintered WC-10Co/Cu nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Gu Dongdong [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China)], E-mail: dongdonggu@nuaa.edu.cn; Shen Yifu [College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, 29 Yudao Street, Nanjing 210016 (China)

    2008-04-30

    In the present work, the direct metal laser sintering (DMLS) process was used to prepare the WC-Co/Cu nanocomposites in bulk form. The WC reinforcing nanoparticles were added in the form of WC-10 wt.% Co composite powder. The microstructural features and mechanical properties of the laser-sintered sample were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX), and nanoindentation tester. It showed that the original nanometric nature of the WC reinforcing particulates was well retained without appreciable grain growth after laser processing. A homogeneous distribution of the WC reinforcing nanoparticles with a coherent particulate/matrix interfacial bonding was obtained in the laser-sintered structure. The 94.3% dense nanocomposites have a dynamic nanohardness of 3.47 GPa and a reduced elastic modulus of 613.42 GPa.

  18. Real-time microradiology of disintegration of iron ore sinteres

    International Nuclear Information System (INIS)

    Kim, Jong Ryun; Kang, H.S.; Lee, Ho Jun; Je, Jung Ho; Jeong, S.K.; Tsai, W.-L.; Hsu, P.C.; Hwu, Y.

    2003-01-01

    We first present real-time microradiology of disintegration of self-fluxing iron ore sinters in low temperature reduction using highly collimated synchrotron source. The experiments were performed on the 5C1 beamline at PLS (Pohang Light Source, Pohang, Korea), operating at 2.5 GeV. We used unmonochromatized ('white') light with no optical elements except beryllium windows. The images of the crack superimpose, on the two-dimensional projection of a three-dimensional phenomenon, suggest that cracks are always initiated from pores in the sinters and propagate along neighboring pores. Interestingly, cracking occurs mostly on macropores (>800 μm), preferentially initiated from stress concentrated sites on pore surfaces. This dynamic study of the disintegration of sinters clearly shows that the crack initiation temperature is as low as 450 deg. C

  19. Temperature Field Simulation of Powder Sintering Process with ANSYS

    Science.gov (United States)

    He, Hongxiu; Wang, Jun; Li, Shuting; Chen, Zhilong; Sun, Jinfeng; You, Ying

    2018-03-01

    Aiming at the “spheroidization phenomenon” in the laser sintering of metal powder and other quality problems of the forming parts due to the thermal effect, the finite element model of the three-dimensional transient metal powder was established by using the atomized iron powder as the research object. The simulation of the mobile heat source was realized by means of parametric design. The distribution of the temperature field during the sintering process under different laser power and different spot sizes was simulated by ANSYS software under the condition of fully considering the influence of heat conduction, thermal convection, thermal radiation and thermophysical parameters. The influence of these factors on the actual sintering process was also analyzed, which provides an effective way for forming quality control.

  20. High efficiency particulate removal with sintered metal filters

    International Nuclear Information System (INIS)

    Kirstein, B.E.; Paplawsky, W.J.; Pence, D.T.; Hedahl, T.G.

    1981-01-01

    Because of their particle removal efficiencies and durability, sintered metal filters have been chosen for HEPA filter protection in the off-gas treatment system for the proposed Idaho National Engineering Laboratory Transuranic Waste Treatment Facility. Process evaluation of sintered metal filters indicated a lack of sufficient process design data to assume trouble-free operation. Subsequent pilot-scale testing was performed with fly ash as the test particulate. The test results showed that the sintered metal filters can have an efficiency greater than 0.9999999 for the specific test conditions used. Stable pressure drop characteristics were observed in pulsed and reversed flow blowback modes of operation. Over 4900 hours of operation were obtained with operating conditions ranging up to approximately 90 0 C and 24 volume percent water vapor in the gas stream

  1. Evaluation of dilatometric techniques for studies of sintering kinetics

    International Nuclear Information System (INIS)

    El-Sayed Ali, M.; Toft Soerensen, O.

    1985-04-01

    The kinetics of the initial sintering stage of CeO 2 is evaluated by three different techniques: constant heating rate dilatometry, constant shrinkage rate dilatometry and a new technique recently introduced by the authors called Stepwise Isothermal Dilatometry (SID). Comparative measurements with these techniques showed that too high activation energies were obtained with the two first techniques, both of which can be termed as nonisothermal, whereas activation energies comparable to those reported for cation diffusion in other fluorite oxides were obtained with the latter technique. Of the three techniques SID is thus considered to be the most accurate for studies of the sintering kinetics. In contrast to the two nonisothermal techniques SID has the further advantage that both the controlling mechanism and its activation energy can be determined in a single experiment. From the SID-measurement it was concluded that the initial sintering stage of CeO 2 is controlled by grain-boundary diffusion. (author)

  2. Sintering and annealing effects on undoped yttria transparent ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Letue, Laetitia; Petit, Johan, E-mail: johan.petit@onera.fr; Ritti, Marie-Hélène; Lalanne, Sylvie; Landais, Stéphane

    2017-06-15

    Transparent yttrium oxide (Y{sub 2}O{sub 3}) ceramics were processed by several densifications steps without any doping species. The green bodies were obtained by the aqueous way and sintered at high temperature under vacuum and then under high pressure. We studied the effects of different sintering cycles and air annealing at different steps of the process on the density and the grain growth. We also focused on the reaction between yttria ceramics and BN-coated graphite crucible which occurs during HIP. We noted that a low heating rate and two annealing steps are necessary to improve our samples’ transparency. - Highlights: • The quality of transparent ceramics is compared with the tested process parameters. • Air annealing is critical when using a carbon environment in the process. • Intra-granular pores, and so the final transparency, are directly linked to the sintering heating rates.

  3. Final flotation waste kinetics of sintering at different heating regimes

    Directory of Open Access Journals (Sweden)

    Cocić Mira

    2016-01-01

    Full Text Available In the copper extraction, especially during the process of flotation enrichment and the pyrometallurgical processing, the waste materials that represent huge polluters of environment are being generated. In order to examine the application of Final flotation waste (FFW in the manufacturing of new materials from the glass-ceramic group phase and mineral composition were examined as well as thermal properties. FFW kinetics of sintering has been tested at different dyamics (1°C/min, 29°C/min and 43°C/min, in order to find the optimum conditions for sintering with a minimum amount of energy and time consumption. The samples were examined using: X-ray diffraction, X-ray fluorescence analysis, SEM (Scanning Electron Microscopy and thermal microscopy. The best results for the production of glass ceramic materials were obtained during the sintering at heating regime of 29°C/min. [Projekat Ministarstva nauke Republike Srbije, br. 176010

  4. Reactive Sintering of Bimodal WC-Co Hardmetals

    Directory of Open Access Journals (Sweden)

    Marek Tarraste

    2015-09-01

    Full Text Available Bimodal WC-Co hardmetals were produced using novel technology - reactive sintering. Milled and activated tungsten and graphite powders were mixed with commercial coarse grained WC-Co powder and then sintered. The microstructure of produced materials was free of defects and consisted of evenly distributed coarse and fine tungsten carbide grains in cobalt binder. The microstructure, hardness and fracture toughness of reactive sintered bimodal WC-Co hardmetals is exhibited. Developed bimodal hardmetal has perspective for demanding wear applications for its increased combined hardness and toughness. Compared to coarse material there is only slight decrease in fracture toughness (K1c is 14.7 for coarse grained and 14.4 for bimodal, hardness is increased from 1290 to 1350 HV units.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7511

  5. Direct laser sintered WC-10Co/Cu nanocomposites

    International Nuclear Information System (INIS)

    Gu Dongdong; Shen Yifu

    2008-01-01

    In the present work, the direct metal laser sintering (DMLS) process was used to prepare the WC-Co/Cu nanocomposites in bulk form. The WC reinforcing nanoparticles were added in the form of WC-10 wt.% Co composite powder. The microstructural features and mechanical properties of the laser-sintered sample were characterized by X-ray diffraction (XRD), atomic force microscope (AFM), scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX), and nanoindentation tester. It showed that the original nanometric nature of the WC reinforcing particulates was well retained without appreciable grain growth after laser processing. A homogeneous distribution of the WC reinforcing nanoparticles with a coherent particulate/matrix interfacial bonding was obtained in the laser-sintered structure. The 94.3% dense nanocomposites have a dynamic nanohardness of 3.47 GPa and a reduced elastic modulus of 613.42 GPa

  6. Immobilization of high-level wastes into sintered glass: 1

    International Nuclear Information System (INIS)

    Russo, D.O.; Messi de Bernasconi, N.; Audero, M.A.

    1987-01-01

    In order to immobilize the high-level radioactive wastes from fuel elements reprocessing, borosilicate glass was adopted. Sintering experiments are described with the variety VG 98/12 (SiO 2 , TiO 2 , Al 2 O 3 , B 2 O 3 , MgO, CaO and Na 2 O) (which does not present devitrification problems) mixed with simulated calcinated wastes. The hot pressing line (sintering under pressure) was explored in two variants 1: In can; 2: In graphite matrix with sintered pellet extraction. With scanning electron microscopy it is observed that the simulated wastes do not disolve in the vitreous matrix, but they remain dispersed in the same. The results obtained point out that the leaching velocities are independent from the density and from the matrix type employed, as well as from the fact that the wastes do no dissolve in the matrix. (M.E.L.) [es

  7. High efficiency particulate removal with sintered metal filters

    International Nuclear Information System (INIS)

    Kirstein, B.E.; Paplawsky, W.J.; Pence, D.T.; Hedahl, T.G.

    1981-01-01

    Because of their particle removal efficiencies and durability, sintered metal filters have been chosen for high efficiency particulate air (HEPA) filter protection in the off-gas treatment system for the proposed Idaho National Engineering Laboratory Transuranic Waste Treatment Facility. Process evaluation of sintered metal filters indicated a lack of sufficient process design data to ensure trouble-free operation. Subsequence pilot scale testing was performed with flyash as the test particulate. The test results showed that the sintered metal filters can have an efficiency greater than 0.9999999 for the specific test conditions used. Stable pressure drop characteristics were observed in pulsed and reversed flow blowback modes of operation. Over 4900 hours of operation were obtained with operating conditions ranging up to approximately 90 0 C and 24 vol % water vapor in the gas stream

  8. Radioactive thickness gauge (1962)

    International Nuclear Information System (INIS)

    Guizerix, J.

    1962-01-01

    The author describes a thickness gauge in which the scintillating crystal detector alternately 'sees' a radioactive source through the material which is to be measured and then a control source of the same material; the radiations are separated in time by an absorbing valve whose sections are alternately full and hollow. The currents corresponding to the two sources are separated beyond the photomultiplier tube by a detector synchronized with the rotation of the valve. The quotient of these two currents is then obtained with a standard recording potentiometer. It is found that the average value of the response which is in the form G = f(I 1 /I 2 ) is not affected by decay of the radioactive sources, and that it is little influenced by variations of high tension, temperature, or properties of the air in the source detector interval. The performance of the gauge is given. (author) [fr

  9. Thick-Big Descriptions

    DEFF Research Database (Denmark)

    Lai, Signe Sophus

    The paper discusses the rewards and challenges of employing commercial audience measurements data – gathered by media industries for profitmaking purposes – in ethnographic research on the Internet in everyday life. It questions claims to the objectivity of big data (Anderson 2008), the assumption...... communication systems, language and behavior appear as texts, outputs, and discourses (data to be ‘found’) – big data then documents things that in earlier research required interviews and observations (data to be ‘made’) (Jensen 2014). However, web-measurement enterprises build audiences according...... to a commercial logic (boyd & Crawford 2011) and is as such directed by motives that call for specific types of sellable user data and specific segmentation strategies. In combining big data and ‘thick descriptions’ (Geertz 1973) scholars need to question how ethnographic fieldwork might map the ‘data not seen...

  10. Sintering and microstructure of ZnO varistor

    International Nuclear Information System (INIS)

    Leite, E.R.; Longo, E.; Varela, J.A.

    1987-01-01

    The sintering and microstructure of ZnO-Bi 2 O 3 (ZB) and ZuO-Sb 2 O 3 -CoO-Bi 2 O 3 (ZSCB) varistors in several temperatures, for one hour in dry air temperature were studied. The compounds were analyzed by scanning electron microscopy, X-ray diffraction, differential thermal analysis and the density and porosity were determined by mercury picnometry. The experimental results showed that the ZB and ZSCB system sinters by liquid means and that liquid will control the density and grain growth mechanisms. (E.G.) [pt

  11. Tool design and materials for electro sinter forging (ESF)

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Chris Valentin

    ) process, the main requirement is the electrical current passing through the electrical conducting powder. To obtain this, a closed-die setup with electrical insulating properties was used. Furthermore, the alignment between the compacting punch and die needed to be ensured by pre-aligning or alternatively...... by using an alignment system. The present work is focused on the designing phase of a tool for the electro sinter forging of a disc, made from titanium powder. By applying a pre-alignment system, the setup resulted suitable for this application. A tool design for sintering rings is also showed....

  12. Sintering of Kernel UO2 for High Temperature Reactor Fuel

    International Nuclear Information System (INIS)

    Sukarsono; Dwi-Heru-Sucahyo; Hidayati; Evi-Hertiviana; Bambang-Sugeng

    2000-01-01

    Sintering investigation of UO 2 gel has been done. The gel was preparedthrough two ways. The first, gel was produced using PVA as additive agent.The second gel was produced using HMTA and Urea as additive agent. From thepreparation of gel, the PVA method better than the urea - HMTA method,because was not necessary the cold temperature for sol preparation and alsowas not necessary the hot temperature for gelation process. After nextprocessing, the sintered gel of gel through PVA, also better than HMTAprocess. (author)

  13. Method and apparatus for radio frequency ceramic sintering

    Science.gov (United States)

    Hoffman, Daniel J.; Kimrey, Jr., Harold D.

    1993-01-01

    Radio frequency energy is used to sinter ceramic materials. A coaxial waveguide resonator produces a TEM mode wave which generates a high field capacitive region in which a sample of the ceramic material is located. Frequency of the power source is kept in the range of radio frequency, and preferably between 60-80 MHz. An alternative embodiment provides a tunable radio frequency circuit which includes a series input capacitor and a parallel capacitor, with the sintered ceramic connected by an inductive lead. This arrangement permits matching of impedance over a wide range of dielectric constants, ceramic volumes, and loss tangents.

  14. Sintering of uranium oxide of high specific surface area

    International Nuclear Information System (INIS)

    Bel, Alain; Francois, Bernard; Delmas, Roger; Caillat, Roger

    1959-01-01

    The extent to which a uranium oxide powder deriving from ammonium uranate or uranium peroxide lends itself to the sintering process depends largely on its specific surface area. When this is greater than 5 m 2 / g there is an optimum temperature for sintering in hydrogen. This temperature becomes less as the specific area of the powder is greater. Reprint of a paper published in Comptes rendus des seances de l'Academie des Sciences, t. 249, p. 1045-1047, sitting of 21 September 1959 [fr

  15. Porous copper template from partially spark plasma-sintered Cu–Zn ...

    Indian Academy of Sciences (India)

    Administrator

    analysis. Keywords. Metal; corrosion; porous structure; sintering; powder metallurgy. 1. Introduction ... well as in the case, when the overall electrode potential of the final ... at 100 °C/min to reach sintering temperature and load was applied ...

  16. The effect of particle size distributions on the microstructural evolution during sintering

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Tikare, V.; Frandsen, Henrik Lund

    2013-01-01

    Microstructural evolution and sintering behavior of powder compacts composed of spherical particles with different particle size distributions (PSDs) were simulated using a kinetic Monte Carlo model of solid state sintering. Compacts of monosized particles, normal PSDs with fixed mean particle...

  17. Thermal Properties of Silver Nanoparticle Sintering Bonding Paste for High-Power LED Packaging

    Directory of Open Access Journals (Sweden)

    Ping Zhang

    2016-01-01

    Full Text Available This paper describes the preparation of low-temperature sintered nanosilver paste with inverse microemulsion method with Span-80/Triton X-100 as the mixed-surfactant and analyzes the influence of different sintering parameters (temperature, pressure on the shear properties of low-temperature sintering of nanosilver. Experimental results show that the shear strength of the low-temperature sintering of nanosilver increases as the temperature and pressure increase. But there are many pores and relative fewer cracks on the sintering layer after low-temperature sintered. The test thermal resistance of low-temperature sintered nanosilver paste is 0.795 K/W which is greater than SAC305 weld layer with a T3ster thermal analyzer. The adhesive performance and the heat dispersion of low-temperature sintered nanosilver paste need to be further researched and improved.

  18. Preparation of Ni-Ti shape memory alloy by spark plasma sintering method

    Czech Academy of Sciences Publication Activity Database

    Salvetr, P.; Kubatík, Tomáš František; Novák, P.

    2016-01-01

    Roč. 16, č. 4 (2016), s. 804-808 ISSN 1213-2489 Institutional support: RVO:61389021 Keywords : Ni-Ti alloy * Powder metallurgy * Reactive sintering * Spark plasma sintering Subject RIV: JK - Corrosion ; Surface Treatment of Materials

  19. Predicting sintering deformation of ceramic film constrained by rigid substrate using anisotropic constitutive law

    International Nuclear Information System (INIS)

    Li Fan; Pan Jingzhe; Guillon, Olivier; Cocks, Alan

    2010-01-01

    Sintering of ceramic films on a solid substrate is an important technology for fabricating a range of products, including solid oxide fuel cells, micro-electronic PZT films and protective coatings. There is clear evidence that the constrained sintering process is anisotropic in nature. This paper presents a study of the constrained sintering deformation using an anisotropic constitutive law. The state of the material is described using the sintering strains rather than the relative density. In the limiting case of free sintering, the constitutive law reduces to a conventional isotropic constitutive law. The anisotropic constitutive law is used to calculate sintering deformation of a constrained film bonded to a rigid substrate and the compressive stress required in a sinter-forging experiment to achieve zero lateral shrinkage. The results are compared with experimental data in the literature. It is shown that the anisotropic constitutive law can capture the behaviour of the materials observed in the sintering experiments.

  20. Disentangling The Thick Concept Argument

    DEFF Research Database (Denmark)

    Blomberg, Olle

    2007-01-01

    Critics argue that non-cognitivism cannot adequately account for the existence and nature of some thick moral concepts. They use the existence of thick concepts as a lever in an argument against non-cognitivism, here called the Thick Concept Argument (TCA). While TCA is frequently invoked...

  1. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    International Nuclear Information System (INIS)

    Huang, Yiqin; Li, Heqin; Zuo, Min; Tao, Lei; Wang, Wei; Zhang, Jing; Tang, Qiong; Bai, Peiwen

    2016-01-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

  2. Corrosion resistance of sintered NdFeB coated with SiC/Al bilayer thin films by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yiqin [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Li, Heqin, E-mail: lhqjs@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zuo, Min; Tao, Lei; Wang, Wei [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Zhang, Jing; Tang, Qiong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009 (China); Bai, Peiwen [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)

    2016-07-01

    The poor corrosion resistance of sintered NdFeB imposes a great challenge in industrial applications. In this work, the SiC/Al bilayer thin films with the thickness of 510 nm were deposited on sintered NdFeB by magnetron sputtering to improve the corrosion resistance. A 100 nm Al buffer film was used to reduce the internal stress between SiC and NdFeB and improve the surface roughness of the SiC thin film. The morphologies and structures of SiC/Al bilayer thin films and SiC monolayer film were investigated with FESEM, AFM and X-ray diffraction. The corrosion behaviors of sintered NdFeB coated with SiC monolayer film and SiC/Al bilayer thin films were analyzed by polarization curves. The magnetic properties were measured with an ultra-high coercivity permanent magnet pulse tester. The results show that the surface of SiC/Al bilayer thin films is more compact and uniform than that of SiC monolayer film. The corrosion current densities of SiC/Al bilayer films coated on NdFeB in acid, alkali and salt solutions are much lower than that of SiC monolayer film. The SiC/Al bilayer thin films have little influence to the magnetic properties of NdFeB. - Highlights: • The same thick Al, SiC and SiC/Al films are deposited on NdFeB by magnetron sputtering. • 510 nm SiC/Al bilayer films can improve the corrosion resistance of the NdFeB evidently. • Al buffer layer improves effectively the surface roughness of the SiC thin film. • SiC/Al bilayer films do not deteriorate the magnetic properties of NdFeB.

  3. Quality prediction modeling for sintered ores based on mechanism models of sintering and extreme learning machine based error compensation

    Science.gov (United States)

    Tiebin, Wu; Yunlian, Liu; Xinjun, Li; Yi, Yu; Bin, Zhang

    2018-06-01

    Aiming at the difficulty in quality prediction of sintered ores, a hybrid prediction model is established based on mechanism models of sintering and time-weighted error compensation on the basis of the extreme learning machine (ELM). At first, mechanism models of drum index, total iron, and alkalinity are constructed according to the chemical reaction mechanism and conservation of matter in the sintering process. As the process is simplified in the mechanism models, these models are not able to describe high nonlinearity. Therefore, errors are inevitable. For this reason, the time-weighted ELM based error compensation model is established. Simulation results verify that the hybrid model has a high accuracy and can meet the requirement for industrial applications.

  4. High sintering resistance of size-selected platinum cluster catalysts by suppressed ostwald ripening

    DEFF Research Database (Denmark)

    Wettergren, Kristina; Schweinberger, Florian F.; Deiana, Davide

    2014-01-01

    on different supports exhibit remarkable intrinsic sintering resistance even under reaction conditions. The observed stability is related to suppression of Ostwald ripening by elimination of its main driving force via size-selection. This study thus constitutes a general blueprint for the rational design...... of sintering resistant catalyst systems and for efficient experimental strategies to determine sintering mechanisms. Moreover, this is the first systematic experimental investigation of sintering processes in nanoparticle systems with an initially perfectly monomodal size distribution under ambient conditions....

  5. Sonographic Measurement of AP Diameter and Wall Thickness of the Gallbladder

    International Nuclear Information System (INIS)

    Chung, S.K.; Lee, J. S.; Huh, S. J.; Baek, I. S.

    1982-01-01

    Call bladder size and wall thickness are important in the assessment of the pathologic condition. Authors have measured AP diameter of gallbladder and evaluated the change of all thickness between fasting and postprandial state. The results were as follows: 1. The mean of AP diameter was 2.18+0.49cm 2. The wall thickness was 2.7+0.6mm in fasting state and 3.3+0.8mm after meal. 3. The increase of wall thickness after fat meal was significant statistically(p<.001)

  6. Thickness-dependent photovoltaic effects in miscut Nb-doped SrTiO3 single crystals

    International Nuclear Information System (INIS)

    Yue Zengji; Zhao Kun; Zhao Songqing; Lu Zhiqing; Li Xiaoming; Ni Hao; Wang Aijun

    2010-01-01

    The photovoltaic effects of Nb-doped SrTiO 3 single crystals with different thicknesses were investigated under the illumination of ultraviolet pulsed lasers. The peak photovoltage increased and then decreased quickly with the decrease in crystal thickness, and a maximum photovoltage occurred for the 180 μm-thick crystal. The photovoltaic response time decreased monotonically with decreasing crystal thickness. The present results suggested the promising potential of reducing crystal thickness in high sensitivity detectors with fast response.

  7. Direct metal laser sintering (DMLS) of a customized titanium mesh for prosthetically guided bone regeneration of atrophic maxillary arches.

    Science.gov (United States)

    Ciocca, L; Fantini, M; De Crescenzio, F; Corinaldesi, G; Scotti, R

    2011-11-01

    This study describes a protocol for the direct manufacturing of a customized titanium mesh using CAD-CAM procedures and rapid prototyping to augment maxillary bone and minimize surgery when severe atrophy or post-oncological deformities are present. Titanium mesh and particulate autogenous plus bovine demineralised bone were planned for patient rehabilitation. Bone augmentation planning was performed using the pre-op CT data set in relation to the prosthetic demands, minimizing the bone volume to augment at the minimum necessary for implants. The containment mesh design was used to prototype the 0.6 mm thickness customized titanium mesh, by direct metal laser sintering. The levels of regenerated bone were calculated using the post-op CT data set, through comparison with the pre-op CT data set. The mean vertical height difference of the crestal bone was 2.57 mm, while the mean buccal-palatal dimension of thickness difference was 3.41 mm. All planned implants were positioned after an 8 month healing period using two-step implant surgery, and finally restored with a partial fixed prosthesis. We present a viable and reproducible method to determine the correct bone augmentation prior to implant placement and CAD-CAM to produce a customized direct laser-sintered titanium mesh that can be used for bone regeneration.

  8. Fast tomosynthesis

    International Nuclear Information System (INIS)

    Klotz, E.; Linde, R.; Tiemens, U.; Weiss, H.

    1978-01-01

    A system has been constructed for fast tomosynthesis, whereby X-ray photographs are made of a single layer of an object. Twenty five X-ray tubes illuminate the object simultaneously at different angles. The resulting coded image is decoded by projecting it with a pattern of lenses that have the same form as the pattern of X-ray tubes. The coded image is optically correlated with the pattern of the sources. The scale of this can be adjusted so that the desired layer of the object is portrayed. Experimental results of its use in a hospital are presented. (C.F.)

  9. Process for the production of metal nitride sintered bodies and resultant silicon nitride and aluminum nitride sintered bodies

    Science.gov (United States)

    Yajima, S.; Omori, M.; Hayashi, J.; Kayano, H.; Hamano, M.

    1983-01-01

    A process for the manufacture of metal nitride sintered bodies, in particular, a process in which a mixture of metal nitrite powders is shaped and heated together with a binding agent is described. Of the metal nitrides Si3N4 and AIN were used especially frequently because of their excellent properties at high temperatures. The goal is to produce a process for metal nitride sintered bodies with high strength, high corrosion resistance, thermal shock resistance, thermal shock resistance, and avoidance of previously known faults.

  10. Improving NASICON Sinterability through Crystallization under High-Frequency Electrical Fields

    Energy Technology Data Exchange (ETDEWEB)

    Lisenker, Ilya; Stoldt, Conrad R., E-mail: stoldt@colorado.edu [Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO (United States)

    2016-03-31

    The effect of high-frequency (HF) electric fields on the crystallization and sintering rates of a lithium aluminum germanium phosphate (LAGP) ion conducting ceramic was investigated. LAGP with the nominal composition Li{sub 1.5}Al{sub 0.5}Ge{sub 1.5}(PO{sub 4}){sub 3} was crystallized and sintered, both conventionally and under effect of electrical field. Electrical field application, of 300 V/cm at 1 MHz, produced up to a 40% improvement in sintering rate of LAGP that was crystallized and sintered under the HF field. Heat sink effect of the electrodes appears to arrest thermal runaway and subsequent flash behavior. Sintered pellets were characterized using X-ray diffraction, scanning electron microscope, TEM, and electrochemical impedance spectroscopy to compare conventionally and field-sintered processes. The as-sintered structure appears largely unaffected by the field as the sintering curves tend to converge beyond initial stages of sintering. Differences in densities and microstructure after 1 h of sintering were minor with measured sintering strains of 31 vs. 26% with and without field, respectively. Ionic conductivity of the sintered pellets was evaluated, and no deterioration due to the use of HF field was noted, though capacitance of grain boundaries due to secondary phases was significantly increased.

  11. Sintering of uranium dioxide pellets (UO2) in an oxidizing atmosphere (C O2)

    International Nuclear Information System (INIS)

    Santos, G.R.T.

    1992-01-01

    This work consists in the study of the sintering process of U O 2 pellets in an oxidizing atmosphere. Sintering tests were performed in an CO 2 atmosphere and the influence of temperature and time on the pellets density and microstructure were verified. The results obtained were compared to those from the conventional sintering process and its efficiency was confirmed. (author)

  12. Rare earth elements in sinters from the geothermal waters (hot springs) on the Tibetan Plateau, China

    Science.gov (United States)

    Feng, Jin-Liang; Zhao, Zhen-Hong; Chen, Feng; Hu, Hai-Ping

    2014-10-01

    The mineralogical and geochemical composition of sinters from the geothermal areas on the Tibetan Plateau was determined. They occur as siliceous, salty and calcareous sinters but biogenic siliceous sinters were also found. The analyses indicate that there are no distinct inter -element relationships between individual rare earth elements (REEs) and other elements. Formed from the same geothermal water, the mineralogical and chemical composition of the sinters is influenced by their genesis and formation conditions. The REE distributions depend on the origin of the sinters. Fe-Mn phases in sinters tend to scavenge more REEs from geothermal water. Neither the REE fractionation nor the Ce anomaly seems to be associated with Fe-Mn phases in the sinters. The fourth tetrads of some sinters display weak W-type (concave) effects. In contrast, the third tetrads present large effects in some sinters due to positive Gd anomalies. The origin of the positive Eu anomalies in some sinters seems to be caused by preferential dissolution of feldspars during water-rock interaction. The complexing ligands in geothermal water may contribute significantly to the fractionation of REEs in sinters. The dominant CO32- and HCO3- complexing in geothermal water favors enrichment of heavy REEs in calcareous sinters.

  13. Influence of various manufacturing parameters on some characteristics of UO2 powders and their sintering behaviour

    International Nuclear Information System (INIS)

    Mintz, M.H.; Vaknin, Sh.; Kremener, A.; Hadari, Z.

    1977-02-01

    Various parameters in the process of manufacturing uranium dioxide are examined and their influence on the characteristics and sintering behaviour of the powders obtained established. In addition some correlations between the powder aggregates microstructure and their adhesion properties and sintering behaviour are indicated. Shrinkage during the sintering process is also discussed

  14. Model for the evaluation and prediction of production rate of sinter ...

    African Journals Online (AJOL)

    A model has been derived for evaluation and prediction of production rate of sinter machine operating on vertical mode. The quadratic model expressed as: P = 0.4395 V – 0.0526 V2 + 0.54, showed that the production rate of the sinter machine was dependent on the vertical sintering height. The maximum deviation of the ...

  15. Microstructure and thermoelectric properties of screen-printed thick-films of misfit-layered cobalt oxides with Ag addition

    DEFF Research Database (Denmark)

    Van Nong, Ngo; Samson, Alfred Junio; Pryds, Nini

    2012-01-01

    Thermoelectric properties of thick (~60 μm) films prepared by a screen-printing technique using p-type misfit-layered cobalt oxide Ca3Co4O9+δ with Ag addition have been studied. The screen-printed films were sintered in air at various temperatures ranging from 973 K to 1223 K. After each sintering...... process, crystal and microstructure analyses were carried out to determine the optimal sintering condition. The results show that the thermoelectric properties of pure Ca3Co4O9+δ thick film are comparable to those of cold isostatic pressing (CIP) samples. We found that the maximum power factor...... was improved by about 67% (to 0.3 mW/m K2) for film with proper silver (Ag) metallic inclusions as compared with 0.18 mW/m K2 for pure Ca3Co4O9+δ film under the same sintering condition of 1223 K for 2 h in air....

  16. BaTiO3 thick fi lms obtained by tape casting from powders prepared by the oxalate route

    Directory of Open Access Journals (Sweden)

    Adelina Ianculescu

    2009-06-01

    Full Text Available BaTiO3 powders were prepared by co-precipitation via oxalate route. The size, morphology and particle size distribution of the oxalate powders have been optimized by the control of different synthesis parameters during the precipitation reaction (nature of salts, concentration of different solutions, aging time. The single phase BaTiO3 oxide particles were obtained after a thermal decomposition of the as-synthesized powders at 850°C for 4 hours under air atmosphere. Oxide powders with a suitable specifi c surface area were selected in order to obtain thick fi lms by the tape casting technique. The microstructure and dielectric properties of the thick films varied obviously depending on the deposition-calcination-sintering cycle used. A double depositioncalcination cycle followed by sintering, as well as a two step deposition-calcination-sintering procedure was used in order to improve the compactness and therefore, the dielectric behaviour. A higher dielectric constant value (~ 750 and lower dielectric losses (~ 2 % were achieved at room temperature and at 1 kHz frequency for the dense, double-deposited fi lm obtained after two deposition-calcination-sintering cycles. For this film, a superior value of the dielectric constant (~ 1100, almost frequency independent in the frequency range of 100 Hz – 10 kHz was gained also at the ferroelectric-paraelectric phase transition temperature of 130°C.

  17. Sinterization of manganese ore tailings under natural air

    Energy Technology Data Exchange (ETDEWEB)

    Lima, M.M.F.; Souza, L.G.P.R.M.F. [Universidade Federal de Ouro Preto (UFOP), MG (Brazil)

    2014-07-01

    The manganese ore has wide application in metallurgy. However, from each of three hundred concentrations found, only one can be seen as a deposit. The aim of this study was to obtain and characterize a sinter from manganese ore tailing. The tailing was milled, classified (<400 ⧣) and calcinated (800°C - 3600s). The mixture had 12% moisture, 7 and 9% of activated charcoal. After homogenization, the sintering were carried out at 1140, 1145 and 1150°C during 1800, 7200 and 14400s at natural air. The sintered products were characterized by EDS analysis, BET surface area, apparent density, X-rays diffraction and SEM/EDS. The mass loss was approximately 14% and 16% in the calcination and sintering, respectively, due to the elimination of volatile products and water. The main phases characterized: SiO2, silicate with high content of manganese in the matrix and other silicates with different proportions of Ti, Na, Mn, Mg and Ca. (author)

  18. Study of sintering on Mg-Zn-Ca alloy system

    Science.gov (United States)

    Annur, Dhyah; Lestari, Franciska P.; Erryani, Aprilia; Kartika, Ika

    2018-05-01

    Magnesium and its alloy have gained a lot of interest to be used in biomedical application due to its biodegradable and biocompatible properties. In this study, sintering process in powder metallurgy was chosen to fabricatenonporous Mg-6Zn-1Ca (in wt%) alloy and porous Mg-6Zn-1Ca-10 Carbamide alloy. For creating porous alloy, carbamide (CO(NH2)2 was added to alloy system as the space holder to create porous structure material. Effect of the space holder addition and sintering temperature on porosity, phase formation, mechanical properties, and corrosion properties was observed. Sintering process was done in a tube furnace under Argon atmosphere in for 5 hours. The heat treatment was done in two steps; heated up at 250 °C for 4 hours to decompose spacer particle, followed by heated up at 580 °C or 630 °C for 5 hours. The porous structure of the resulted alloys was examined using Scanning Electron Microscope (SEM), while the phase formation was characterized by X-ray diffraction (XRD) analysis. Mechanical properties were examined using compression testing. From this study, increasing sintering temperature up to 630 °C reduced the mechanical properties of Mg-Zn-Ca alloy.

  19. New membranes made of sintered clay application to crossflow ...

    African Journals Online (AJOL)

    The new mineral membranes made of sintered clay are performed and characterized in terms of porosity, hydraulic resistance, pore diameter and mechanical resistance. It is shown that these membranes can be used as microfiltration membrane. The variations of the filtrate flux as a function of time are measured during the ...

  20. 2D phase field modeling of sintering of silver nanoparticles

    NARCIS (Netherlands)

    Chockalingam, K.; Kouznetsova, V.; van der Sluis, O.; Geers, M.G.D.

    2016-01-01

    The sintering mechanism of silver nanoparticles is modelled by incorporating surface, volume and grain boundary diffusion in a phase field model. A direction-dependent tensorial mobility formulation is adopted, capturing the fact that diffusion mainly occurs along the directions tangential to the

  1. Effect of sintering temperature and time on the mechanical ...

    Indian Academy of Sciences (India)

    Administrator

    that the shape of stress–strain curves were similar to each other, compacted ... sample sintered at 1250°C for 3 h showed an appropriate range of pore sizes and interconnectivity. The ..... Ping Li J, de Wijn J R, Van Blitterswijk C A and de Groot.

  2. Physical chemistry and modelling of the sintering of actinide oxides

    International Nuclear Information System (INIS)

    Lechelle, Jacques

    2013-01-01

    This report gives a synthesis of the work I have carried out or to which I have numerically contributed to from 1996 up to 2012 in the Department of Plutonium Uranium and minor Actinides in Cadarache CEA Center. Their main goal is the study and the modeling of the sintering process of nuclear fuels which is the unifying thread of this document. Both in order to take into account the physical and chemical features of the actinide bearing oxide material and in order to combine the different transport phenomena leading to sintering, a sub-granular scale model is under development. Extension to a varying chemical composition as well as exchanges with the gaseous phase are foreseen. A simulation on a larger scale (pellet scale) is ongoing in the framework of a PhD thesis. Validation means have been tested with (U,Pu)O 2 material on the scale of the pellet (Small Angle Neutron Diffusion), on the scale of powder granules (X-Ray High Resolution Micro-Tomography) and with CeO 2 at the 'Institut de Chimie Separative' in Marcoule on a single crystal scale (Environmental Scanning Electron Microscope). The required microstructure homogeneity for nuclear fuels has led to a campaign of experimental studies about the role of Cr 2 O 3 as a sintering aid. Whole of these studies improve our understanding of fuel sintering and hence leads to an improved mastering of this process. (author) [fr

  3. Novel sintered ceramic materials incorporated with EAF carbon steel slag

    Science.gov (United States)

    Karayannis, V.; Ntampegliotis, K.; Lamprakopoulos, S.; Papapolymerou, G.; Spiliotis, X.

    2017-01-01

    In the present research, novel sintered clay-based ceramic materials containing electric arc furnace carbon steel slag (EAFC) as a useful admixture were developed and characterized. The environmentally safe management of steel industry waste by-products and their valorization as secondary resources into value-added materials towards circular economy have attracted much attention in the last years. EAF Carbon steel slag in particular, is generated during the manufacture of carbon steel. It is a solid residue mainly composed of rich-in- Fe, Ca and Si compounds. The experimental results show that the beneficial incorporation of lower percentages of EAFC up to 6%wt. into ceramics sintered at 950 °C is attained without significant variations in sintering behavior and physico-mechanical properties. Further heating up to 1100 °C strongly enhances the densification of the ceramic microstructures, thus reducing the porosity and strengthening their mechanical performance. On the other side, in terms of thermal insulation behavior as well as energy consumption savings and production cost alleviation, the optimum sintering temperature appears to be 950 °C.

  4. Development of synthetic graphite resistive elements for sintering furnace

    International Nuclear Information System (INIS)

    Otani, C.; Rezende, Mirabel C.; Polidoro, H.A.; Otani, S.

    1987-01-01

    The synthetic graphites have been produced using lignin coke, natural graphite and phenolic resin. The bulk density, porosity, flexural strength and eletrical resistivity measurements have been performed on specimens at about 2400 0 C. The performance of these materials, as heating elements, was evaluated in a sintering furnace prototype. This paper reports the fabrication process and the experimental results. (Author) [pt

  5. Sintering of wax for controlling release from pellets.

    Science.gov (United States)

    Singh, Reena; Poddar, S S; Chivate, Amit

    2007-09-14

    The purpose of the present study was to investigate incorporation of hydrophobic (ie, waxy) material into pellets using a thermal sintering technique and to evaluate the pellets in vitro for controlled release. Pellets prepared by extrusion-spheronization technology were formulated with a water-soluble drug, microcrystalline cellulose, and carnauba wax. Powdered carnauba wax (4%-20%) prepared by grinding or by emulsification was studied with an attempt to retard the drug release. The inclusion of ground or emulsified carnauba wax did not sustain the release of theophylline for more than 3 hours. Matrix pellets of theophylline prepared with various concentrations of carnauba wax were sintered thermally at various times and temperatures. In vitro drug release profiles indicated an increase in drug release retardation with increasing carnauba wax concentration. Pellets prepared with ground wax showed a higher standard deviation than did those prepared with emulsified wax. There was incomplete release at the end of 12 hours for pellets prepared with 20% ground or emulsified wax. The sintering temperature and duration were optimized to allow for a sustained release lasting at least 12 hours. The optimized temperature and duration were found to be 100 degrees C and 140 seconds, respectively. The sintered pellets had a higher hydrophobicity than did the unsintered pellets. Scanning electron micrographs indicated that the carnauba wax moved internally, thereby increasing the surface area of wax within the pellets.

  6. Conventional and two step sintering of PZT-PCN ceramics

    Science.gov (United States)

    Keshavarzi, Mostafa; Rahmani, Hooman; Nemati, Ali; Hashemi, Mahdieh

    2018-02-01

    In this study, PZT-PCN ceramic was made via sol-gel seeding method and effects of conventional sintering (CS) as well as two-step sintering (TSS) were investigated on microstructure, phase formation, density, dielectric and piezoelectric properties. First, high quality powder was achieved by seeding method in which the mixture of Co3O4 and Nb2O5 powder was added to the prepared PZT sol to form PZT-PCN gel. After drying and calcination, pyrochlore free PZT-PCN powder was synthesized. Second, CS and TSS were applied to achieve dense ceramic. The optimum temperature used for 2 h of conventional sintering was obtained at 1150 °C; finally, undesired ZrO2 phase formed in CS procedure was removed successfully with TSS procedure and dielectric and piezoelectric properties were improved compared to the CS procedure. The best electrical properties obtained for the sample sintered by TSS in the initial temperature of T 1 = 1200 °C and secondary temperature of T 2 = 1000 °C for 12 h.

  7. Fractal characterization of the compaction and sintering of ferrites

    NARCIS (Netherlands)

    Glass, H.J.; With, de G.

    2001-01-01

    A novel parameter, the fractal exponent DE, is derived using the concept of fractal scaling. The fractal exponent DE relates the development of a feature within a material to the development of the size of the material. As an application, structural changes during the compaction and sintering of

  8. New developments in laser sintering of diamond cutting disks

    NARCIS (Netherlands)

    Kovalenko, V.; Golovko, L.; Meijer, J.; Anyakin, M.

    2007-01-01

    The analysis of techniques and problems in the fabrication of cutting tools based on super hard composites results in a solution by the application of lasers. The results of systematic study of diamond composites sintering with laser radiation are discussed. A mathematical modeling of the heat

  9. High-level radioactive waste fixation in sintered vitreous matrix

    International Nuclear Information System (INIS)

    Russo, D.O.; Messi de Bernasconi, N.; Audero, M.A.

    1987-01-01

    The safe storage of high-level wastes from fuel elements reprocessing includes, as a first step, the fixation of the same in materials having a good resistance to the leaching in aqueous medium, such as borosilicate glass. As an alternative to the usual method of the molten glasses, a procedure for the sintering of a powdered glass and waste mixture at lower temperatures (600-700 deg C) has been developed, which minimizes the volatilization of active compounds during the process. Two glasses matrices of different composition and characteristics were used, to which the simulated wastes were added in the ratio of a 10% in weight of oxides. Two sintering techniques were employed 1: cold pressing and further sintering; 2: hot pressing and sintering under pressure. The densities were measured, the microstructure of the samples was analyzed and leaching essays were made in distilled water. The pellet's microstructure was observed by means of optical microscopy, by reflection in polished samples and by transparency in thin slices. The presence of crystalline compounds was analyzed by means of x rays and electron microprobe. The results have shown the convenience to continue with hot pressing essays, because a denser product with a higher resistance to the leaching is thus obtained. (M.E.L.) [es

  10. Two step sintering of zirconia-escandia-ceria

    International Nuclear Information System (INIS)

    Grosso, R.L.; Muccillo, E.N.S.

    2011-01-01

    Recent reports show that the ceramic system based on zirconia-scandia-ceria is a good candidate to act as solid electrolyte in solid oxide fuel cells operating at intermediate temperatures (600-800 °C). In this work, commercial ZrO_2 containing 10 mol% scandium oxide and 1 mol% cerium oxide was sintered by the two stage method. This technique was proposed to in order to obtain ceramic materials with high density along with fine grain sizes, because it avoids the grain growth occurring in the last stage of sintering. A number of experimental conditions were fully exploited by varying the dwell temperature (T_2) and the dwell time. The peak temperature (T_1) was chosen from linear shrinkage results. High (>98%) density values were obtained using this method. The medium grain size was evaluated for selected sintered samples. X-ray diffraction patterns reveal a secondary (rhombohedral) phase in sintered samples. The intensity of the secondary phase is a function of T_1 being small for relatively higher peak temperatures. (author)

  11. Modeling of the effective thermal conductivity of sintered porous pastes

    NARCIS (Netherlands)

    Ordonez-Miranda, J.; Hermens, M.; Nikitin, I.; Kouznetsova, V.G.; Volz, S.

    2014-01-01

    The thermal conductivity of sintered porous pastes of metals is modelled, based on an analytical and a numerical approach. The first method arises from the differential effective medium theory and considers the air voids as ellipsoidal pores of different sizes, while second one is based on the

  12. Coal fly ash utilization: Low temperature sintering of wall tiles

    International Nuclear Information System (INIS)

    Chandra, Navin; Sharma, Priya; Pashkov, G.L.; Voskresenskaya, E.N.; Amritphale, S.S.; Baghel, Narendra S.

    2008-01-01

    We present here a study of the sintering of fly ash and its mixture with low alkali pyrophyllite in the presence of sodium hexa meta phosphate (SHMP), a complex activator of sintering, for the purpose of wall tile manufacturing. The sintering of fly ash with SHMP in the temperature range 925-1050 deg. C produces tiles with low impact strength; however, the incremental addition of low alkali pyrophyllite improves impact strength. The impact strength of composites with ≥40% (w/w) pyrophyllite in the fly ash-pyrophyllite mix satisfies the acceptable limit (19.6 J/m) set by the Indian Standards Institute for wall tiles. Increasing the pyrophyllite content results in an increase in the apparent density of tiles, while shrinkage and water absorption decrease. The strength of fly ash tiles is attributed to the formation of a silicophosphate phase; in pyrophyllite rich tiles, it is attributed to the formation of a tridymite-structured T-AlPO 4 phase. Scanning electron micrographs show that the reinforcing rod shaped T-AlPO 4 crystals become more prominent as the pyrophyllite content increases in the sintered tiles

  13. Consolidation of copper and aluminium powders by spark plasma sintering

    Science.gov (United States)

    Saiprasad, M.; Atchayakumar, R.; Thiruppathi, K.; Raghuraman, S.

    2016-09-01

    Processing in the powder metallurgy route has emerged as an economical process for the production of near net shaped components with a wide range of desired mechanical properties suitable for various applications of industrial needs. This research work was conducted with an objective of studying the improvisation of density and hardness of Copper-Aluminium alloy prepared by spark plasma sintering. Cu-Al alloy with a composition of 95% copper and 5% aluminium was prepared by SPS process. SPS is a low voltage, DC pulse current activated, pressure-assisted sintering, which enables sintering at lower temperatures and shorter durations. The combination offered by Cu-Al alloy of high strength and high corrosion resistance results their applications under a wide variety of conditions. The density and hardness of the prepared sample were measured by conducting appropriate tests. Apparently, the values of hardness and density of the specimen prepared by SPS seemed to be better than that of conventional sintering. The experimental procedure, testing methodologies and analysis are presented.

  14. Binding Mechanisms in Selective Laser Sintering and Selective Laser Melting

    NARCIS (Netherlands)

    Kruth, J.P.; Mercelis, P.; Van Vaerenbergh, J.; van Vaerenbergh, J.; Froyen, L.; Rombouts, M.

    2005-01-01

    Purpose – This paper provides an overview of the different binding mechanisms in selective laser sintering (SLS) and selective laser melting (SLM), thus improving the understanding of these processes. Design/methodology/approach – A classification of SLS/SLM processes was developed, based on the

  15. Pressure-assisted sintering of high purity barium titanate

    NARCIS (Netherlands)

    van den Cruijsem, S.; Varst, van der P.G.T.; With, de G.; Bortzmeyer, D.; Boussuge, M.; Chartier, Th.; Hausonne, J.M.; Mocellin, A.; Rousset, A.; Thevenot, F.

    1997-01-01

    The dielectric behaviour of High Purity Barium titanate (HPB) ceramics is strongly dependent on the grain size and porosity. For applications, control of grain size and porosity is required. Pressure-assisted sintering techniques at relatively low temperatures meet these requirements. In this study,

  16. Creation and Validation of Sintered PTFE BRDF Targets & Standards.

    Science.gov (United States)

    Durell, Christopher; Scharpf, Dan; McKee, Greg; L'Heureux, Michelle; Georgiev, Georgi; Obein, Gael; Cooksey, Catherine

    2015-09-21

    Sintered polytetrafluoroethylene (PTFE) is an extremely stable, near-perfect Lambertian reflecting diffuser and calibration standard material that has been used by national labs, space, aerospace and commercial sectors for over two decades. New uncertainty targets of 2 % on-orbit absolute validation in the Earth Observing Systems community have challenged the industry to improve is characterization and knowledge of almost every aspect of radiometric performance (space and ground). Assuming "near perfect" reflectance for angular dependent measurements is no longer going to suffice for many program needs. The total hemispherical spectral reflectance provides a good mark of general performance; but, without the angular characterization of bidirectional reflectance distribution function (BRDF) measurements, critical data is missing from many applications and uncertainty budgets. Therefore, traceable BRDF measurement capability is needed to characterize sintered PTFE's angular response and provide a full uncertainty profile to users. This paper presents preliminary comparison measurements of the BRDF of sintered PTFE from several laboratories to better quantify the BRDF of sintered PTFE, assess the BRDF measurement comparability between laboratories, and improve estimates of measurement uncertainties under laboratory conditions.

  17. Damage radiation alpha effects in sintered waste form

    International Nuclear Information System (INIS)

    Messi de Bernasconi, Norma B.; Prado, Miguel O.; Bevilacqua, Arturo M.; Arribere, Maria; Heredia, Arturo D.; Sanfilippo, Miguel

    1999-01-01

    We have subjected the borosilicate glass to thermal neutron irradiation in a reactor, with an accumulated fluence equivalent to approximately E3, E4, E5, y E6 years of waste disposal. We considered the following potential effects of accumulated alpha decay: a) Changes in the density; b) Changes in the dissolution rates; c) Changes in the microstructure of the sintered glass. (author)

  18. Electric Field-Assisted Pressureless Sintering of Ceramic Protonic Conductors

    DEFF Research Database (Denmark)

    Muccillo, R.; Esposito, Vincenzo; de Florio, D. Z.

    2017-01-01

    Gadolinium, yttrium and samarium-doped barium cerate pressed pellets were submitted to flash sintering experiments isothermally in the temperature range 800-1300oC under 200 V cm-1 electric field. The pellets were positioned inside a dilatometer furnace with Pt-Ir electrodes connected either to a...

  19. Electric Field-Assisted Pressureless Sintering of Ceramic Protonic Conductors

    DEFF Research Database (Denmark)

    Muccillo, R.; Esposito, Vincenzo; Zanetti De Florio, Daniel

    2017-01-01

    Gadolinium, yttrium and samarium-doped barium cerate (BCGd, BCY and BCSm, respectively) polycrystalline green pellets were submitted to electric field-assisted pressureless sintering experiments isothermally in the temperature range 800-1200oC under 100-200 V cm-1 electric fields, limiting to 1-5...

  20. Preparation and mechanism of the sintered bricks produced from Yellow River silt and red mud

    International Nuclear Information System (INIS)

    He, Hongtao; Yue, Qinyan; Su, Yuan; Gao, Baoyu; Gao, Yue; Wang, Jingzhou; Yu, Hui

    2012-01-01

    Highlights: ► The best condition was red mud content of 40% and sintering at 1050 °C for 2 h. ► Bricks’ weight loss was caused by the removal of absorbed water and crystal water. ► Bricks’ sintering shrinkage depended on the sodium and iron compounds of red mud. ► Sintering can strengthen bricks and decrease leaching concentration of toxic metal. - Abstract: The preparation, characteristics and mechanisms of sintered bricks manufactured by Yellow River silt and red mud were studied. The sintering shrinkage, weight loss on ignition, water absorption and compressive strength were tested to determine the optimum preparation condition. Sintering mechanisms were discussed through linear regression analysis. Crystalline components of raw materials and bricks were analyzed by X-ray diffraction. Leaching toxicity of raw materials and bricks were measured according to sulphuric acid and nitric acid method. Radiation safety of the sintered bricks was characterized by calculating internal exposure index and external exposure index. The results showed that at the chosen best parameters (red mud content of 40%, sintering temperature of 1050 °C and sintering time of 2 h), the best characteristics of sintered bricks could be obtained. The weight loss on ignition of sintered bricks was principally caused by the removal of absorbed water and crystal water. The sintering shrinkage of sintered bricks mainly depended on sodium compounds and iron compounds of red mud. The sintering process made some components of raw materials transform into other crystals having better thermostability. Besides, the leaching toxicity and radioactivity index of sintered bricks produced under the optimum condition were all below standards.

  1. Contribution to the modelling of solid state sintering

    International Nuclear Information System (INIS)

    Martin, Sylvain

    2014-01-01

    This thesis deals with the simulation of the sintering of nuclear fuel on a pellet scale. The goal is to develop numerical tools which can contribute to a better understanding of the physical phenomena involved in the sintering process. Hence, a multi scale approach is proposed. First of all, a Discrete Element model is introduced. It aims at modeling the motion of particles on a Representative Elementary Volume scale using an original Discrete Element Method. The latter is a Non Smooth Method called Contact Dynamics. Recently, there have been numerous papers about the simulation of sintering using Discrete Element Method. As far as we know, all these papers use smooth methods. Different studies show that the results match well experimental data. However, some limits come from the fact that smooth methods use an explicit scheme which needs very small time steps. In order to obtain an acceptable time step, the mass of particles have to be dramatically increased. The Non Smooth Contact Dynamics uses an implicit scheme, thus time steps can be much larger without scaling up the mass of particles. The comparison between smooth and non smooth approaches shows that our method leads to a more realistic representation of rearrangement. An experimental validation using synchrotron X-Ray microtomography is then presented, followed by a parametric study on the sintering of bimodal powders that aims at showing the capacity of this model. The second part presents a mechanical model on the sub-Granular scale, using a Finite Element method. This targets a better understanding of the behavior of two grains in contact. The model is currently being developed but the first results already show that some parameters like the shape of the surface of the neck are very sensitive. In the future, the Non smooth Contact Dynamics model of sintering may be improved using the results obtained by the sub-Granular scale mechanical model. (author) [fr

  2. Final report on initial samples supplied by LLNL for task 3.3 binder burnout and sintering schedule optimisation

    Energy Technology Data Exchange (ETDEWEB)

    Walls, P

    1999-01-04

    Sixteen of the twenty-one samples have been investigated using the scanning laser dilatometer. This includes all three types of samples with different preparation routes and organic content. Cracks were observed in all samples, even those only heated to 300 C. It was concluded that the cracking was occurring in the early part of the heat treatment before the samples reached 300 C. Increase in the rate of dilation of the samples occurred above 170 C which coincided with the decomposition of the binder/wax additives as determined by differential thermal analysis. A comparison was made with SYNROC C material (Powder Run 143), samples of which had been CIPed and green machined to a similar diameter and thickness as the 089 mm SRTC pucks. These samples contained neither binder nor other organic processing aids and had been kept in the same desiccator as the SRTC samples. The CIPed Synroc C samples sintered to high density with zero cracks. As the cracks made up only a small contribution to the change in diameter of the sample compared to the sintering shrinkage, useful information could still be gained from the runs. The sintering curves showed that there was much greater shrinkage of the Type III samples containing only the 5% PEG binder compared to the Type I which contained polyolefin wax as processing aid. Slight changes in gradient of the sintering curve were observed, however, due to the masking effect of the cracking, full analysis of the sintering kinetics cannot be conducted. Even heating the samples to 300 C at 1.0 or 0.5 C/min could not prevent crack formation. This indicated that heating rate was not the critical parameter causing cracking of the samples. Sectioning of green bodies revealed the inhomogeneous nature of the binder/lubricant distribution in the samples. Increased homogeneity would reduce the amount of binder/lubricant required, which should in turn, reduce the degree of cracking observed during heating to the binder burnout temperature. A

  3. Glass-ceramic coating material for the CO2 laser based sintering of thin films as caries and erosion protection.

    Science.gov (United States)

    Bilandžić, Marin Dean; Wollgarten, Susanne; Stollenwerk, Jochen; Poprawe, Reinhart; Esteves-Oliveira, Marcella; Fischer, Horst

    2017-09-01

    The established method of fissure-sealing using polymeric coating materials exhibits limitations on the long-term. Here, we present a novel technique with the potential to protect susceptible teeth against caries and erosion. We hypothesized that a tailored glass-ceramic material could be sprayed onto enamel-like substrates to create superior adhesion properties after sintering by a CO 2 laser beam. A powdered dental glass-ceramic material from the system SiO 2 -Na 2 O-K 2 O-CaO-Al 2 O 3 -MgO was adjusted with individual properties suitable for a spray coating process. The material was characterized using X-ray fluorescence analysis (XRF), heating microscopy, dilatometry, scanning electron microscopy (SEM), grain size analysis, biaxial flexural strength measurements, fourier transform infrared spectroscopy (FTIR), and gas pycnometry. Three different groups of samples (each n=10) where prepared: Group A, powder pressed glass-ceramic coating material; Group B, sintered hydroxyapatite specimens; and Group C, enamel specimens (prepared from bovine teeth). Group B and C where spray coated with glass-ceramic powder. All specimens were heat treated using a CO 2 laser beam process. Cross-sections of the laser-sintered specimens were analyzed using laser scanning microscopy (LSM), energy dispersive X-ray analysis (EDX), and SEM. The developed glass-ceramic material (grain size d50=13.1mm, coefficient of thermal expansion (CTE)=13.310 -6 /K) could be spray coated on all tested substrates (mean thickness=160μm). FTIR analysis confirmed an absorption of the laser energy up to 95%. The powdered glass-ceramic material was successfully densely sintered in all sample groups. The coating interface investigation by SEM and EDX proved atomic diffusion and adhesion of the glass-ceramic material to hydroxyapatite and to dental enamel. A glass-ceramic material with suitable absorption properties was successfully sprayed and laser-sintered in thin films on hydroxyapatite as well as on

  4. Microwave-assisted reactive sintering and lithium ion conductivity of Li1.3Al0.3Ti1.7(PO4)3 solid electrolyte

    Science.gov (United States)

    Hallopeau, Leopold; Bregiroux, Damien; Rousse, Gwenaëlle; Portehault, David; Stevens, Philippe; Toussaint, Gwenaëlle; Laberty-Robert, Christel

    2018-02-01

    Li1.3Al0.3Ti1.7(PO4)3 (LATP) materials are made of a three-dimensional framework of TiO6 octahedra and PO4 tetrahedra, which provides several positions for Li+ ions. The resulting high ionic conductivity is promising to yield electrolytes for all-solid-state Li-ion batteries. In order to elaborate dense ceramics, conventional sintering methods often use high temperature (≥1000 °C) with long dwelling times (several hours) to achieve high relative density (∼90%). In this work, an innovative synthesis and processing approach is proposed. A fast and easy processing technique called microwave-assisted reactive sintering is used to both synthesize and sinter LATP ceramics with suitable properties in one single step. Pure and crystalline LATP ceramics can be achieved in only 10 min at 890 °C starting from amorphous, compacted LATP's precursors powders. Despite a relative density of 88%, the ionic conductivity measured at ambient temperature (3.15 × 10-4 S cm-1) is among the best reported so far. The study of the activation energy for Li+ conduction confirms the high quality of the ceramic (purity and crystallinity) achieved by using this new approach, thus emphasizing its interest for making ion-conducting ceramics in a simple and fast way.

  5. Processing parameters for ZnO-based thick film varistors obtained by screen printing

    Directory of Open Access Journals (Sweden)

    de la Rubia, M. A.

    2006-06-01

    Full Text Available Thick film varistors based on the ZnO-Bi2O3-Sb2O3 system have been prepared by screen printing on dense alumina substrates. Different processing parameters like the paste viscosity, burn out and sintering cycles, green and sintered thickness, have been studied to improve the processing of ZnO-based thick film varistors. Starting powders were pre-treated in two different ways in order to control both the Bi-rich liquid phase formation and the excessive volatilization of Bi2O3 during sintering due to the high area/volume ratio of the thick films. Significant changes have been observed in the electrical properties related to the different firing schedule and selection of the starting powders.

    Se han preparado varistores basados en el sistema ZnO-Bi2O3-Sb2O3 en forma de lámina gruesa sobre sustratos de alúmina densa. Diferentes parámetros del procesamiento como la viscosidad de la pasta, los ciclos de calcinación y sinterización y el espesor en verde y sinterizado han sido estudiados para mejorar el procesamiento de los varistores basados en ZnO preparados en forma de lámina gruesa. Los polvos de partida fueron pretratados de dos formas diferentes con el objetivo de controlar la formación de la fase líquida rica en bismuto y la excesiva volatilización de Bi2O3 durante la sinterización debida a la alta relación área-volumen de las láminas gruesas. Se han observado cambios significativos en las propiedades eléctricas relacionadas con los diferentes ciclos de calcinado y con la selección de los polvos de partida.

  6. Translucence in dental prosthesis based on zirconia ceramics: effect of the sintering parameters

    International Nuclear Information System (INIS)

    Santos, C.

    2011-01-01

    In this work the translucence of Zirconia dental ceramics was evaluated as function of sintering conditions (temperature and isothermal holding time). Samples with 15x15x1mm, were sintered at 1450 to 1600 deg C, with holding of 2h or 4h. Sintered samples were characterized by relative density, crystalline phases and microstructural aspects. Full density was obtained in samples sintered at 1530 and 1600 deg C, which presented higher grain sizes. Na increasing of translucence was observed in samples sintered at 1530 and 1600, correlating these properties with increasing of density and grain size of the samples. (author)

  7. Ir-based refractory superalloys by pulse electric current sintering (PECS) process (II prealloyed powder)

    Science.gov (United States)

    Huang, C.; Yamabe-Mitarai, Y.; Harada, H.

    2002-02-01

    Five prealloyed powder samples prepared from binary Ir-based refractory superalloys were sintered at 1800 °C for 4 h by Pulse Electric Current Sintering (PECS). No metal loss was observed during sintering. The relative densities of the sintered specimens all exceeded 90% T.D. The best one was Ir-13% Hf with the density of 97.82% T.D. Phases detected in sintered samples were in accordance with the phase diagram as expected. Fractured surfaces were observed in two samples (Ir-13% Hf and Ir-15% Zr). Some improvements obtained by using prealloyed powders instead of elemental powders, which were investigated in the previous studies, were presented.

  8. Kinetics of UO{sub 2} sintering; Kinetika sinterovanja UO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ristic, M M [Institute of Nuclear Sciences Vinca, Laboratorija za reaktorske materijale, Beograd (Serbia and Montenegro)

    1962-10-15

    Detailed conclusions related to the UO{sub 2} sintering can be drawn from investigating the kinetics of the sintering process. This report gives an thorough analysis of the the data concerned with sintering available in the literature taking into account the Jander and Arrhenius laws. This analysis completes the study of influence of the O/U ratio and the atmosphere on the sintering. Results presented are fundamentals of future theoretical and experimental work related to characterisation of the UO{sub 2} sintering process.

  9. Effect of sintering process parameters on the properties of 3Y-PSZ ceramics

    International Nuclear Information System (INIS)

    Chu, H L; Chen, R S; Wang, C L; Hwang, W S; Lee, H E; Sie, Y Y; Wang, M C

    2013-01-01

    The effect of sintering process parameters on the properties of 3 mol% yttria partially stability zirconia (3Y-PSZ) ceramics has been investigated. The relative density of the sintered pellet rapidly increases from 70.5 to 93.6% with rose temperature from 1473 to 1573 K. In addition, the relative density only slightly increases from 94.9 to 96.6 %, when rose sintered temperature from 1573 to 1773 K. This result shows that no significant influence on the densification behavior when sintering at 1573 to 1773 K for 2 h. The Vickers hardness and toughness also increase with the sintered temperature

  10. Effect of sintering temperature on the densification of B4C pellets

    International Nuclear Information System (INIS)

    Gomide, R.G.; Durazzo, M.; Riella, H.G.

    1990-01-01

    Boron is largely used in several types of nuclear reactors control and safety systems. In the majority of these applications sintered boron carbide pellets are used. Near stoichiometric B 4 C hardly densifies during pressureless sintering. As a starting point of an overall program to produce > 70% TD B 4 C pellets pressing parameters have been studied for further study of the influence of sintering temperature in the densification of this ceramic material. Dilatometric analyses show that sintering starts at 1760 0 C for the F 1200 ESK - type boron carbide powders. Moreover, the sintering experiments show that up to 92% TD pellets can be obtained. (author) [pt

  11. Expeditious low-temperature sintering of copper nanoparticles with thin defective carbon shells

    Science.gov (United States)

    Kim, Changkyu; Lee, Gyoungja; Rhee, Changkyu; Lee, Minku

    2015-04-01

    The realization of air-stable nanoparticles, well-formulated nanoinks, and conductive patterns based on copper is a great challenge in low-cost and large-area flexible printed electronics. This work reports the synthesis of a conductively interconnected copper structure via thermal sintering of copper inks at a low temperature for a short period of time, with the help of thin defective carbon shells coated onto the copper nanoparticles. Air-stable copper/carbon core/shell nanoparticles (typical size ~23 nm, shell thickness ~1.0 nm) are prepared by means of an electric explosion of wires. Gaseous oxidation of the carbon shells with a defective structure occurs at 180 °C, impacting the choice of organic solvents as well as the sintering conditions to create a crucial neck formation. Isothermal oxidation and reduction treatment at 200 °C for only about 10 min yields an oxide-free copper network structure with an electrical resistivity of 25.1 μΩ cm (14.0 μΩ cm at 250 °C). Finally, conductive copper line patterns are achieved down to a 50 μm width with an excellent printing resolution (standard deviation ~4.0%) onto a polyimide substrate using screen printing of the optimized inks.The realization of air-stable nanoparticles, well-formulated nanoinks, and conductive patterns based on copper is a great challenge in low-cost and large-area flexible printed electronics. This work reports the synthesis of a conductively interconnected copper structure via thermal sintering of copper inks at a low temperature for a short period of time, with the help of thin defective carbon shells coated onto the copper nanoparticles. Air-stable copper/carbon core/shell nanoparticles (typical size ~23 nm, shell thickness ~1.0 nm) are prepared by means of an electric explosion of wires. Gaseous oxidation of the carbon shells with a defective structure occurs at 180 °C, impacting the choice of organic solvents as well as the sintering conditions to create a crucial neck formation

  12. Microstructure Evolution and Mechanical Properties Improvement in Liquid-Phase-Sintered Hydroxyapatite by Laser Sintering

    Directory of Open Access Journals (Sweden)

    Songlin Duan

    2015-03-01

    Full Text Available CaO-Al2O3-SiO2 (CAS as a liquid phase was introduced into hydroxyapatite (HAp to prepare bone scaffolds. The effects of the CAS content (1, 2, 3, 4 and 5 wt% on microstructure and mechanical properties of HAp ceramics were investigated. The optimal compression strength, fracture toughness and Vickers hardness reached 22.22 MPa, 1.68 MPa·m1/2 and 4.47 GPa when 3 wt% CAS was added, which were increased by 105%, 63% and 11% compared with those of HAp ceramics without CAS, respectively. The improvement of the mechanical properties was attributed to the improved densification, which was caused by the solid particle to rearrange during liquid phase sintering. Moreover, simulated body fluid (SBF study indicated the HAp ceramics could maintain the mechanical properties and form a bone-like apatite layer when they were immersed in SBF. Cell culture was used to evaluate biocompatibility of the HAp ceramics. The results demonstrated MG-63 cells adhered and spread well.

  13. Coercivity enhancement of Dy-free Nd–Fe–B sintered magnets by intergranular adding Ho{sub 63.4}Fe{sub 36.6} alloy

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Liping; Ma, Tianyu, E-mail: maty@zju.edu.cn; Wu, Chen; Zhang, Pei; Liu, Xiaolian; Yan, Mi, E-mail: mse_yanmi@zju.edu.cn

    2016-01-01

    High coercivity Nd–Fe–B sintered magnets serving in high-temperature environments always consume expensive and scarce heavy rare-earth Dy, which has simulated considerable interest to reduce Dy usage. In this work, coercivity of Dy-free magnets was investigated through intergranular adding eutectic Ho{sub 63.4}Fe{sub 36.6} powders. The coercivity increases gradually up to 4 wt% Ho{sub 63.4}Fe{sub 36.6} addition, however the remanence starts to deteriorate drastically as the addition is over 2.5 wt%. Coercivity above 18.0 kOe is obtained at the expense of a slight reduction in remanence through optimizing the addition amount and sintering conditions. The coercivity enhancement is explained through microstructural observations and elemental distribution analysis. (i) (Nd, Ho){sub 2}Fe{sub 14}B shell forms in the outer region of 2:14:1 phase grains, strengthening the local magnetic anisotropy filed, (ii) RE-rich grain boundary phase with low Fe content is thickened, weakening the magnetic coupling between adjacent 2:14:1 phase grains, and (iii) 2:14:1 phase grains are refined upon lowering sintering temperature, reducing the microstructural defects and the stray fields aroused from neighboring grains. - Highlights: • Eutectic Ho{sub 63.4}Fe{sub 36.6} powders were intergranular added to NdFeB sintered magnets. • The doped Dy-free magnet possessed coercivity of 18.0 kOe, remanence of 13.15 kGs. • (Nd, Ho){sub 2}Fe{sub 14}B shell formed in the surface of the matrix grains, increasing the H{sub A}. • Thick grain boundaries with low Fe content formed, decoupling the matrix grains. • By sintered at lower temperature, the matrix phase grains were refined.

  14. Note on measurement of thermal conductivity of sintered uranium dioxide; Note relative a la mesure de la conductivite thermique du bioxyde d'uranium fritte

    Energy Technology Data Exchange (ETDEWEB)

    Englander, M

    1951-06-01

    Thermal conductivity of sintered UO{sub 2} was determined by measuring the quantity of heat having passed in unit time through a plate of given dimensions when a certain temperature difference was being maintained at the faces of the plate. Specimens, about 10 and 40 mm thick and about 65 mm in diameter, were heated electrically, the temperature of both faces being measured by means of iron-constantan thermocouples. The accuracy of the device in its present shape is not high, the relative error being {approx} 15%. The thermal conductivity of sintered UO{sub 2} in the temperature range 20 to 250 deg. C was found to be about 9 x 10{sup -3} cgs units. (author)

  15. Impedance spectroscopy evolution upon sintering of Al-rich anodising sludge-based extruded bodies

    Directory of Open Access Journals (Sweden)

    Ribeiro, M. J.

    2006-08-01

    Full Text Available Alumina based ceramic materials, containing Al-rich sludge as the major component, were processed by extrusion. The sludge derived from the wastewater treatment of aluminium anodising industrial process. Long rods were produced using a vacuum screw extruder, by a careful control of all relevant processing parameters. Then, thick discs were obtained by cutting dried selected rods, to be tested as probes for sintering-dependent electrical properties. The sintering process was followed by performing common dilatometric/thermal analyses but the evolution of electrical conductivity, estimated by impedance spectroscopy (IS, was also used for this purpose. Results show that sintering-dependent morphological evolution up to 1300ºC strongly affects the electrical behaviour of samples, and as a consequence IS seems to be a useful technique to follow the firing process.

    Los materiales cerámicos basados en alúmina, conteniendo barros ricos en Al como componente mayoritario fueron procesados por extrusión. Los barros empleados provienen de tratamientos de lavado de residuos de un proceso industrial de anodizado de aluminio. Se produjeron varillas empleando un extrusor de tornillo en vacío con control de todos los parámetros relevantes del proceso. A partir de varillas seleccionadas, se obtuvieron por corte en seco discos cerámicos para evaluar la dependencia de la sinterización y las propiedades eléctricas. El proceso de sinterización se siguió mediante ensayos dilatométricos y análisis térmicos, junto con la evolución de la conductividad eléctrica mediante espectroscopia de impedancia. Los resultados mostraron la evolución de la sinterización y la dependencia morfológica hasta 1300ºC, que afecta fuertemente a la respuesta eléctrica y como consecuencia la espectroscopia de impedancia parece ser una técnica útil en el seguimiento de los procesos de cocción.

  16. Preparation of Nd–Fe–B sintered magnets from HDDR-processed powder

    Energy Technology Data Exchange (ETDEWEB)

    Takagi, Kenta, E-mail: k-takagi@aist.go.jp [Green Innovative Magnetic Materials Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Akada, Misaho [Magnetic Materials R& D Center, Research Associations of Magnetic Materials for High-Efficiency Motors (MagHEM), Nagoya 463-8560 (Japan); Soda, Rikio; Ozaki, Kimihiro [Green Innovative Magnetic Materials Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan)

    2015-11-01

    The electric-current sintering technique was used to fully densify hydrogenation–disproportionation–desorption–recombination (HDDR)-processed Nd–Fe–B powder at temperatures below the grain growth temperature in order to produce high-coercive bulk magnets. However, the sintered magnets exhibited anomalous coercivity reduction that depended on sintered density. Reheating examination of the sintered magnets revealed that the reduced coercivity was increased in proportion to the heating temperature, resulting in complete recovery of coercivity. As a result, the combination of electric-current sintering and post-annealing produced sintered magnets with a coercivity of 15 kOe. Scanning and transmission electron microscopy revealed no evidence that associated the anomalous coercivity reduction and recovery with grain boundary morphology. On the other hand, various HDDR powders with different particle sizes were sintered, and finer powders yielded lower coercivity after sintering, implying that the anomalous coercivity reduction was associated with particle surface oxides of the raw powder. - Highlights: • We conduct a sintering of HDDR-processed Nd–Fe–B powder without coercivity reduction. • Rapid current sintering allows densification of this powder without grain growth. • However, the sintered magnets show an anomalous coercivity reduction phenomenon. • It is found that post-annealing completely recovers the reduced coercivity. • The anomalous coercivity reduction would be due to surface oxide of the raw powder.

  17. Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

    International Nuclear Information System (INIS)

    Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke

    2015-01-01

    Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysis also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs

  18. Sintered tantalum carbide coatings on graphite substrates: Highly reliable protective coatings for bulk and epitaxial growth

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Daisuke; Suzumura, Akitoshi; Shigetoh, Keisuke [Toyota Central R and D Labs., Inc., Nagakute, Aichi 480-1192 (Japan)

    2015-02-23

    Highly reliable low-cost protective coatings have been sought after for use in crucibles and susceptors for bulk and epitaxial film growth processes involving wide bandgap materials. Here, we propose a production technique for ultra-thick (50–200 μmt) tantalum carbide (TaC) protective coatings on graphite substrates, which consists of TaC slurry application and subsequent sintering processes, i.e., a wet ceramic process. Structural analysis of the sintered TaC layers indicated that they have a dense granular structure containing coarse grain with sizes of 10–50 μm. Furthermore, no cracks or pinholes penetrated through the layers, i.e., the TaC layers are highly reliable protective coatings. The analysis also indicated that no plastic deformation occurred during the production process, and the non-textured crystalline orientation of the TaC layers is the origin of their high reliability and durability. The TaC-coated graphite crucibles were tested in an aluminum nitride (AlN) sublimation growth process, which involves extremely corrosive conditions, and demonstrated their practical reliability and durability in the AlN growth process as a TaC-coated graphite. The application of the TaC-coated graphite materials to crucibles and susceptors for use in bulk AlN single crystal growth, bulk silicon carbide (SiC) single crystal growth, chemical vapor deposition of epitaxial SiC films, and metal-organic vapor phase epitaxy of group-III nitrides will lead to further improvements in crystal quality and reduced processing costs.

  19. Gas response properties of citrate gel synthesized nanocrystalline MgFe{sub 2}O{sub 4}: Effect of sintering temperature

    Energy Technology Data Exchange (ETDEWEB)

    Patil, J.Y. [School of Physical Sciences, Solapur University Solapur-413255 (India); Mulla, I.S. [Emeritus Scientist (CSIR), Centre for Materials for Electronic Technology(C-MET) Pune-411 008 (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.com [School of Physical Sciences, Solapur University Solapur-413255 (India)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► Synthesis of nanocrystalline MgFe{sub 2}O{sub 4} by economical citrate gel combustion method. ► Structural, morphological, and gas response properties of MgFe{sub 2}O{sub 4}. ► Enhancement in selectivity of MgFe{sub 2}O{sub 4} towards LPG with sintering temperature. ► Use of MgFe{sub 2}O{sub 4} to detect different gases at different operating temperatures. -- Abstract: Spinel type MgFe{sub 2}O{sub 4} material was synthesized by citrate gel combustion method. The effect of sintering temperature on structural, morphological, and gas response properties was studied. The powder X-ray diffraction pattern and transmission electron microscope study confirms nanocrystalline spinel structure of the synthesized powder. The material was tested for response properties to various reducing gases like liquid petroleum gas (LPG), acetone, ethanol, and ammonia. The results demonstrated n-type semiconducting behavior of MgFe{sub 2}O{sub 4} material. It was revealed that MgFe{sub 2}O{sub 4} sintered at 973 K was most sensitive to LPG at 648 K and to acetone at 498 K. However MgFe{sub 2}O{sub 4} sintered at 1173 K exhibited higher response and selectivity to LPG with marginal increase in the operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. It was observed that the particles size, porosity, and surface activity of the sensor material is affected by the sintering temperature.

  20. Disruption of an Alumina Layer During Sintering of Aluminium in Nitrogen

    Directory of Open Access Journals (Sweden)

    Pieczonka T.

    2017-06-01

    Full Text Available Aluminium oxide layer on aluminium particles cannot be avoided. However, to make the metal-metal contacts possible, this sintering barrier has to be overcome in some way, necessarily to form sintering necks and their development. It is postulated that the disruption of alumina layer under sintering conditions may originate physically and chemically. Additionally, to sinter successfully non alloyed aluminium powder in nitrogen, the operation of both types mechanism is required. It is to be noted that metallic aluminium surface has to be available to initiate reactions between aluminium and the sintering atmosphere, i.e. mechanical disruption of alumina film precedes the chemical reactions, and only then chemically induced mechanisms may develop. Dilatometry, gravimetric and differential thermal analyses, and microstructure investigations were used to study the sintering response of aluminium at 620°C in nitrogen, which is the only sintering atmosphere producing shrinkage.

  1. Evaluation of Sintering Behavior of Premix Al-Zn-Mg-Cu Alloy Powder

    Directory of Open Access Journals (Sweden)

    Haris Rudianto

    2015-01-01

    Full Text Available Sintering of light aluminium alloys powder has been investigated as a way to substitute steels in automotive and aerospace industries. Premix Al-5.5Zn-2.5Mg-0.5Cu composite powder called Alumix 431D was analyzed in this research. Sintering was carried out under ultra high purity nitrogen gas and before reaching sintering temperature, green samples were delubricated at 400°C for 30 min. The powder possesses high sinterability by reaching 96% relative density at 580°C sintering temperature. Formation of liquid phase seems to support achieving high sintering density. Optimum mechanical properties also were obtained under those conditions. T6 heat treatment was done to improve the mechanical properties by formation of precipitation strengthening, and MgZn2 appears to be dominant strengthening precipitate. X-ray diffraction, optical microscopy, and SEM-EDS were used to characterize powder, and sintered and heat treated samples.

  2. The effects of surface finish and grain size on the strength of sintered silicon carbide

    Science.gov (United States)

    You, Y. H.; Kim, Y. W.; Lee, J. G.; Kim, C. H.

    1985-01-01

    The effects of surface treatment and microstructure, especially abnormal grain growth, on the strength of sintered SiC were studied. The surfaces of sintered SiC were treated with 400, 800 and 1200 grit diamond wheels. Grain growth was induced by increasing the sintering times at 2050 C. The beta to alpha transformation occurred during the sintering of beta-phase starting materials and was often accompanied by abnormal grain growth. The overall strength distributions were established using Weibull statistics. The strength of the sintered SiC is limited by extrinsic surface flaws in normal-sintered specimens. The finer the surface finish and grain size, the higher the strength. But the strength of abnormal sintering specimens is limited by the abnormally grown large tabular grains. The Weibull modulus increases with decreasing grain size and decreasing grit size for grinding.

  3. Low density, variation in sintered density and high nitrogen in uranium dioxide

    International Nuclear Information System (INIS)

    Balakrishna, Palanki; Murty, B.N.; Anuradha, M.; Nageshwara Rao, P.; Jayaraj, R.N.; Ganguly, C.

    2000-01-01

    Low sintered density and density variation in sintered UO 2 were found to have been caused by non uniformity in the granule feed characteristics to the compacting press. The nitrogen impurity content of sintered UO 2 was found to be sintering furnace related and associated with low sintered density pellets. The problems of low density, variation in sintered density and high nitrogen could be solved by the replacement of the prevailing four punch precompaction by a single punch process; by the introduction of a vibro-sieve for the separation of fine particles from the press feed granules; by innovation in the powder feed shoe design for simultaneous and uniform dispensing of powder in all the die holes; by increasing the final compaction pressure and by modifying the gas flows and preheat temperature in the sintering furnace. (author)

  4. Improved microstructure and thermoelectric properties of iodine doped indium selenide as a function of sintering temperature

    Science.gov (United States)

    Dhama, Pallavi; Kumar, Aparabal; Banerji, P.

    2018-04-01

    In this paper, we explored the effect of sintering temperature on the microstructure, thermal and electrical properties of iodine doped indium selenide in the temperature range 300 - 700 K. Samples were prepared by a collaborative process of vacuum melting, ball milling and spark plasma sintering at 570 K, 630 K and 690 K. Single phase samples were obtained at higher sintering temperature as InSe is stable only at lower temperature. With increasing sintering temperature, densities of the samples were found to improve with larger grain size formation. Negative values of Seebeck coefficient were observed which indicates n-type carrier transport. Seebeck coefficient increases with sintering temperature and found to be the highest for the sample sintered at 690 K. Thermal conductivity found to be lower in the samples sintered at lower temperatures. The maximum thermoelectric figure of merit found to be ˜ 1 at 700 K due to the enhanced power factor as a result of improved microstructure.

  5. Static and dynamic through thickness lamina properties of thick laminates

    NARCIS (Netherlands)

    Lahuerta, F.; Nijssen, R.P.L.; Van der Meer, F.P.; Sluys, L.J.

    2015-01-01

    Thick laminates are increasingly present in large composites structures such as wind turbine blades. Different factors are suspected to be involved in the decreased static and dynamic performance of thick laminates. These include the effect of self-heating, the scaling effect, and the manufacturing

  6. The effect of lanthanum boride on the sintering, sintered microstructure and mechanical properties of titanium and titanium alloys

    International Nuclear Information System (INIS)

    Yang, Y.F.; Luo, S.D.; Qian, M.

    2014-01-01

    An addition of ≤0.5 wt% lanthanum boride (LaB 6 ) to powder metallurgy commercially pure Ti (CP-Ti), Ti–6Al–4V and Ti–10V–2Fe–3Al (all in wt%) resulted in improved sintered density, substantial microstructural refinement, and noticeably increased tensile elongation. The addition of LaB 6 led to scavenging of both oxygen (O) and chlorine (Cl) from the titanium powder during sintering, evidenced by the formation of La 2 O 3 and LaCl x O y . The pinning effect of La 2 O 3 , LaCl x O y and TiB inhibited prior-β grain growth and resulted in subsequent smaller α-laths. The formation of nearly equiaxed α-Ti phase is partially attributed to the nucleation effect of α-Ti on TiB. The improved sintered density was caused by B from LaB 6 rather than La, while excessive formation of La 2 O 3 and TiB with an addition of >0.5 wt% LaB 6 resulted in a noticeable decrease in sintered density. The improved tensile elongation with an addition of ≤0.5 wt% LaB 6 was mainly attributed to the scavenging of oxygen by LaB 6 , partially assisted by the improved sintered density. However, an addition of >0.5 wt% LaB 6 led to the formation of large La 2 O 3 aggregates and more brittle TiB whiskers and therefore decreased tensile elongation. Balanced scavenging of O is thus important. The optimal addition of LaB 6 was 0.5 wt% but this may change depending on the powder size of the LaB 6 to be used

  7. Low Temperature Two-Steps Sintering (LTTSS) - an innovative method for consolidating porous UO2 pellets

    International Nuclear Information System (INIS)

    Sanjay Kumar, D.; Ananthasivan, K.; Senapati, Abhiram; Venkata Krishnan, R.

    2015-01-01

    Metallic uranium and its alloys are an important fuel for fast reactors. Presently, metallic uranium is being prepared using expensive fluoro-metallothermic process. Recent reports suggest that metal oxide could be reduced to metal using a novel electrochemical de-oxidation method and this could serve as attractive alternate for expensive metallothermic process. In view of which, a research program is being pursued in our Centre to develop an optimum process parameter for the scaled up preparation of metallic uranium efficiently. One of the important process parameter is the size, nature and distribution of porosity in the urania pellet. Essentially the ceramic form of the urania should encompass interconnected porosity that would allow percolation of melts into the UO 2 . However, the matrix density of the pellet should be high to ensure that it possesses good handling strength and is electrically conducting. Hence preparation of high dense porous UO 2 pellets was required. In this study, we report the preparation of porous UO 2 pellets possessing a very high matrix density by using the citrate gel-combustion method. The 'as-prepared' powders were consolidated at various compaction pressures as such and these pellets were sintered in 8 mol %Ar+H 2 gas with a flow rate of 250 mL/min at 1073 K for 30 min followed by soaking at 1473 K for 4 h with heating rate of 5 K min -1 in a molybdenum furnace. X-ray diffraction studies revealed that these pellets contained UO 2 . The morphological analysis sintered pellets was carried out by using Scanning Electron Microscope (M/s. Philips model XL 30, Netherlands). All these pellets were gold coated

  8. Multispectral UV imaging for determination of the tablet coating thickness

    DEFF Research Database (Denmark)

    Novikova, Anna; Carstensen, Jens Michael; Zeitler, J. Axel

    2017-01-01

    The applicability of off-line multispectral ultraviolet (UV) imaging in combination with multivariate data analysis was investigated to determine the coating thickness and its distribution on the tablet surface during lab scale coating. The UV imaging results were compared with the weight gain...... measured for each individual tablet and the corresponding coating thickness and its distribution measured by terahertz pulsed imaging (TPI). Three different tablet formulations were investigated, two of which contained UV active tablet cores. Three coating formulations were applied: Aquacoat® ECD (a mainly...... translucent coating) and Eudragit® NE (a turbid coating containing solid particles). It was shown that UV imaging is a fast and non-destructive method to predict individual tablet weight gain as well as coating thickness. The coating thickness distribution profiles determined by UV imaging correlated...

  9. A practical method for in-situ thickness determination using energy distribution of beta particles

    International Nuclear Information System (INIS)

    Yalcin, S.; Gurler, O.; Gundogdu, O.; Bradley, D.A.

    2012-01-01

    This paper discusses a method to determine the thickness of an absorber using the energy distribution of beta particles. An empirical relationship was obtained between the absorber thickness and the energy distribution of beta particles transmitted through. The thickness of a polyethylene radioactive source cover was determined by exploiting this relationship, which has largely been left unexploited allowing us to determine the in-situ cover thickness of beta sources in a fast, cheap and non-destructive way. - Highlights: ► A practical and in-situ unknown cover thickness determination ► Cheap and readily available compared to other techniques. ► Beta energy spectrum.

  10. Optimum target thickness for polarimeters

    International Nuclear Information System (INIS)

    Sitnik, I.M.

    2003-01-01

    Polarimeters with thick targets are a tool to measure the proton polarization. But the question about the optimum target thickness is still the subject of discussion. An attempt to calculate the most common parameters concerning this problem, in a few GeV region, is made

  11. Mems-based pzt/pzt bimorph thick film vibration energy harvester

    DEFF Research Database (Denmark)

    Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian

    2011-01-01

    We describe fabrication and characterization of a significantly improved version of a MEMS-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass. The main advantage of bimorph vibration energy harvesters is that strain energy is not lost in mechanical...... support materials since only PZT is strained, and thus it has a potential for significantly higher output power. An improved process scheme for the energy harvester resulted in a robust fabrication process with a record high fabrication yield of 98.6%. Moreover, the robust fabrication process allowed...... a high pressure treatment of the screen printed PZT thick films prior to sintering, improving the PZT thick film performance and harvester power output reaches 37.1 μW at 1 g....

  12. Fabrication and characterization of MEMS-based PZT/PZT bimorph thick film vibration energy harvesters

    DEFF Research Database (Denmark)

    Xu, Ruichao; Lei, Anders; Dahl-Petersen, Christian

    2012-01-01

    We describe the fabrication and characterization of a significantly improved version of a microelectromechanical system-based PZT/PZT thick film bimorph vibration energy harvester with an integrated silicon proof mass; the harvester is fabricated in a fully monolithic process. The main advantage...... yield of 98%. The robust fabrication process allowed a high pressure treatment of the screen printed PZT thick films prior to sintering. The high pressure treatment improved the PZT thick film performance and increased the harvester power output to 37.1 μW at 1 g root mean square acceleration. We also...... characterize the harvester performance when only one of the PZT layers is used while the other is left open or short circuit....

  13. Ethanol vapour sensing properties of screen printed WO 3 thick films

    Indian Academy of Sciences (India)

    The ethanol vapour sensing properties of these thick films were investigated at different operating temperatures and ethanol vapour concentrations. The WO3 thick films exhibit excellent ethanol vapour sensing properties with a maximum sensitivity of ∼1424.6% at 400°C in air atmosphere with fast response and recovery ...

  14. Thickness dependence of light transmittance, translucency and opalescence of a ceria-stabilized zirconia/alumina nanocomposite for dental applications.

    Science.gov (United States)

    Shiraishi, Takanobu; Watanabe, Ikuya

    2016-05-01

    This study was conducted to investigate thickness dependence of light transmittance, translucency and opalescence of a commercially available fully-sintered ceria-stabilized zirconia/alumina nanocomposite for dental all-ceramic restorations. Three disk samples of 16 mm in diameter and thickness ranging from 0.2 to 0.6 mm with 0.1 mm increment each were cut from a fully-sintered rod-shaped Ce-TZP/alumina nanocomposite (NANOZR, Panasonic Healthcare, Japan) and polished flat by using diamond slurry. Spectral light transmittance data under the CIE standard illuminant D65 were recorded at 10nm intervals from 360 to 740 nm using a computer-controlled spectrophotometer. Average transmittance, translucency and opalescence parameters were determined as a function of sample thickness. Optical properties of a fully-sintered yttria-stabilized tetragonal zirconia polycrystals (Cercon(®) base, DeguDent GmbH, Germany) were also investigated as a reference. Two-way ANOVA was performed to determine the significant differences in various optical parameters among types of ceramic and thicknesses at α=0.05. Results of the two-way ANOVA showed that the average transmittance, translucency and opalescence parameters of both ceramic materials were significantly influenced by the type of ceramic and thickness (popalescence parameters exceeding 20 CIE units when the sample thickness was nearly 0.3 mm. The prominent characteristics of high opalescence and low transmittance of light in the NANOZR was considered to be caused by its specific very fine interpenetrated intragranular microstructure and by a large difference of refractive indices of Ce-TZP and alumina components. High opalescence and low transmittance of light of the ceria-stabilized zirconia/alumina nanocomposite (NANOZR) are attractive properties for use as a substructure in fabricating porcelain-veneering-type esthetic all-ceramic restorations. Copyright © 2016 Academy of Dental Materials. Published by Elsevier Ltd. All

  15. Rapid immobilization of simulated radioactive soil waste by microwave sintering.

    Science.gov (United States)

    Zhang, Shuai; Shu, Xiaoyan; Chen, Shunzhang; Yang, Huimin; Hou, Chenxi; Mao, Xueli; Chi, Fangting; Song, Mianxin; Lu, Xirui

    2017-09-05

    A rapid and efficient method is particularly necessary in the timely disposal of seriously radioactive contaminated soil. In this paper, a series of simulated radioactive soil waste containing different contents of neodymium oxide (3-25wt.%) has been successfully vitrified by microwave sintering at 1300°C for 30min. The microstructures, morphology, element distribution, density and chemical durability of as obtained vitrified forms have been analyzed. The results show that the amorphous structure, homogeneous element distribution, and regular density improvement are well kept, except slight cracks emerge on the magnified surface for the 25wt.% Nd 2 O 3 -containing sample. Moreover, all the vitrified forms exhibit excellent chemical durability, and the leaching rates of Nd are kept as ∼10 -4 -10 -6 g/(m 2 day) within 42days. This demonstrates a potential application of microwave sintering in radioactive contaminated soil disposal. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Experimental performance evaluation of sintered Gd spheres packed beds

    DEFF Research Database (Denmark)

    Tura, A.; Nielsen, Klaus K.; Van Nong, Ngo

    2016-01-01

    Research in magnetic refrigeration heavily relies on the use of packed spheres in regenerators, however little investigation to verify that such non-monolithic arrangements guarantee a sufficiently constrained structure has yet been performed. This work presents a preliminary comparison of the pe......Research in magnetic refrigeration heavily relies on the use of packed spheres in regenerators, however little investigation to verify that such non-monolithic arrangements guarantee a sufficiently constrained structure has yet been performed. This work presents a preliminary comparison...... of the performance of AMRs consisting of Gd spheres with diameters ranging from 450-550 microns partially sintered by Spark Plasma Sintering (SPS) to similar spheres, sorted in the same size range and from the same batch, but merely packed. Pressure drop is compared at uniform temperature and at a range of heat...

  17. Glass phase expelling during liquid phase sintering of YSZ

    International Nuclear Information System (INIS)

    Souza, Milton Ferreira de; Souza, Dulcina Pinatti Ferreira de

    1998-01-01

    Expelling of the liquid phase during sintering of Zr O 2 -6.5 mol % Y 2 O 3 - 0.5 mol % Pr 2 O 3 ceramic was observed as a result of grain coarsening. ZrO 2 - 7.0 mol % Y 2 O 3 samples, without Pr 2 O 3 addition, do not show this effect under the same sintering conditions. The expelling process is caused by surface tension forces and attracting van der Waals forces between the grains, coupled with the existence of two glass phases on the grain boundaries. The amount of expelled glass phase increases with grain growth, but saturates above 16 μm average grain size. (author)

  18. COMPACTION OF LITHIUM-SILICATE CERAMICS USING SPARK PLASMA SINTERING

    Directory of Open Access Journals (Sweden)

    Tomas Frantisek Kubatik

    2016-12-01

    Full Text Available This paper deals with the compaction of ceramics based on lithium-silicate by spark plasma sintering (SPS. The initial powder was prepared by calcination in a resistance furnace at a temperature of 1300 °C with the ratio of Li/Si = 1. Compacting by SPS was carried out at temperatures of 800 - 1000 °C with a maximum pressure of 80 MPa. Samples with open porosity of less than 1 % were prepared at the temperature of 1000 °C. According to the quantitative Rietveld refinement of x-ray diffraction data, the dominant phases in all samples were Li₂Si₂O₅ and Li₂SiO₃, together representing over 80 wt. % of the sintered material.

  19. Influence of metallic additives on manganese ferrites sintering

    Science.gov (United States)

    Shevelev, S. A.; Luchnikov, P. A.; Yarullina, A. R.

    2018-01-01

    Influence of cuprum nanopowder additive received by electric explosion on the process of manganese ferrites MgFe2O4 consolidating at thermal sintering was researched by dilatometry method. Cuprum nanopowder at a rate of 5 mass % was added into the original commercial-grade powder of manganese ferrite MgFe2O4. Powder mixture was numerously blended with screening for better blending before pressing. Powder compacts were formed by cold one-axle static pressing. It was proved that introduction of cuprum additive caused shrinkage increase at final heating stage. There was abnormal compact enlarging at sintering in the air at isothermal stage; the specified process was not observed in vacuum. This difference can be explained by changes in conditions of gaseous discharge from volume of pores.

  20. Sintering of cermets on the base of corundum and molybdenum

    International Nuclear Information System (INIS)

    Fedotov, A.V.

    1987-01-01

    Liquid-phase sintering of cermets has been studied to develop rational technology allowing to produce a dense material at lower temperatures. Molybdenum of the MPCh mark with the specific surface ranged from 1900 to 4000 cm 2 /g and the corundum powder of the VK-94-1 mark with the specific surface of 6000 cm 2 /g containing upto 10% of the glass-phase have been used as initial materials. It is shown that application of the VK-94-1 ceramics powder for molybdenum content cermets allows to decrease the temperature of dense material production (∼ upto 100 deg C). To produce dense materials, it is necessary to restrict the initial porosity of compaction and to correspond it to the sintering conditions. The increase of molybdenum dispersion allows to produce material with the more homogeneous structure, higher density and strength. Molybdenum presence decreases recrystallization of corundum crystals and causes structure production resistant to high-temperature heating

  1. Strain rate dependency of laser sintered polyamide 12

    Directory of Open Access Journals (Sweden)

    Cook J.E.T.

    2015-01-01

    Full Text Available Parts processed by Additive Manufacturing can now be found across a wide range of applications, such as those in the aerospace and automotive industry in which the mechanical response must be optimised. Many of these applications are subjected to high rate or impact loading, yet it is believed that there is no prior research on the strain rate dependence in these materials. This research investigates the effect of strain rate and laser energy density on laser sintered polyamide 12. In the study presented here, parts produced using four different laser sintered energy densities were exposed to uniaxial compression tests at strain rates ranging from 10−3 to 10+3 s−1 at room temperature, and the dependence on these parameters is presented.

  2. Effects of B2O3-Li2O additions on the dielectric properties of screen printing Ba0.6Sr0.4TiO3 thick films

    International Nuclear Information System (INIS)

    Zeng, Yike; Gao, Can; Zhang, Guangzu; Jiang, Shenglin

    2012-01-01

    Ba 0.6 Sr 0.4 TiO 3 (BST) thick films were fabricated on Al 2 O 3 substrate via the screen printing technology by using B 2 O 3 -Li 2 O additions as liquid-phase sintering aids. The effects of doping of B 2 O 3 and Li 2 CO 3 on the phase compositions, microstructures, and dielectric tunable properties of the thick films were investigated systematically. The X-ray diffraction patterns showed that BST diffraction peaks shifted toward higher angle with the B 2 O 3 -Li 2 O doping content, which indicated the substitution of B 3+ and Li + in Ba 2+ site. It was also found that the grain size and electrical properties of the thick film were strongly affected by the glass content. The grain size and the relative permittivity decreased obviously with the increase of B 2 O 3 -Li 2 O additive. In addition, for the thick film with 4.5 wt% glass content, optimized sintering, and electrical properties were obtained: the sintering temperature of 900 C, relative permittivity of 312 (at 10 kHz), dielectric loss of 0.0039, tunability of 16.2% (at 3 kV/mm). These good sintering and electrical properties indicate that BST thick film with B 2 O 3 -Li 2 O addition is benefit for the development of LTCC technology and tunable devices. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Splitting diffraction peak in different thickness LL-interferometer and determination of thickness of damaged layer induced by electron irradiation of plates

    International Nuclear Information System (INIS)

    Truni, K.G.; Sedrakyan, A.G.; Papoyan, A.A.; Bezirganyan, P.A.

    1988-01-01

    Amplitude of twice reflected beam is calculated analytically, oscillatory dependence of peak intensity in the centre of diffraction image on the small variations in thickness is shown. The expression, clearly binding the splitting value of diffraction peak with variation in thickness of the interferometer plates, is received. The effect of variation in thickness on the splitting value of focal line is studied experimentally in case of irradiation of the equal-arm Π-shaped interferometer blocks by fast electron flow, thickness of the originated damaged layers are determined

  4. Lanthanide (Nd, Gd) compounds with garnet and monazite structures. Powders synthesis by “wet” chemistry to sintering ceramics by Spark Plasma Sintering

    Energy Technology Data Exchange (ETDEWEB)

    Potanina, Ekaterina, E-mail: ekaterina.potanina@list.ru [Department of Solid State Chemistry, Lobachevsky State University of Nizhni Novgorod, National Research University, 23 Prospekt Gagarina, BLDG 2, 603950 Nizhny Novgorod (Russian Federation); Golovkina, Ludmila, E-mail: golovkina_lyudmila@mail.ru [Department of Solid State Chemistry, Lobachevsky State University of Nizhni Novgorod, National Research University, 23 Prospekt Gagarina, BLDG 2, 603950 Nizhny Novgorod (Russian Federation); Orlova, Albina, E-mail: albina.orlova@inbox.ru [Department of Solid State Chemistry, Lobachevsky State University of Nizhni Novgorod, National Research University, 23 Prospekt Gagarina, BLDG 2, 603950 Nizhny Novgorod (Russian Federation); Nokhrin, Aleksey, E-mail: nokhrin@nifti.unn.ru [Research Institute of Physics and Technology, Lobachevsky State University of Nizhni Novgorod, National Research University, 23 Prospekt Gagarina, BLDG 3, 603950 Nizhny Novgorod (Russian Federation); Boldin, Maksim, E-mail: boldin@nifti.unn.ru [Research Institute of Physics and Technology, Lobachevsky State University of Nizhni Novgorod, National Research University, 23 Prospekt Gagarina, BLDG 3, 603950 Nizhny Novgorod (Russian Federation); Sakharov, Nikita, E-mail: nvsaharov@nifti.unn.ru [Research Institute of Physics and Technology, Lobachevsky State University of Nizhni Novgorod, National Research University, 23 Prospekt Gagarina, BLDG 3, 603950 Nizhny Novgorod (Russian Federation)

    2016-05-15

    Complex oxide Y{sub 2.5}Nd{sub 0.5}Al{sub 5}O{sub 12} with garnet structure and phosphates NdPO{sub 4} and GdPO{sub 4} with monazite structure were obtained by using precipitation methods. Ceramics Y{sub 2.5}Nd{sub 0.5}Al{sub 5}O{sub 12} and NdPO{sub 4} were processed by Spark Plasma Sintering (SPS). Relative density more 98%, sintering time did not exceed 8 min, sintering temperature 1330–1390 °C. Leaching rates of elements from ceramics were 10{sup −6}–10{sup −7} g/(cm{sup 2} d). The process of ceramics sintering has two-stage character: the first step of sintering-compaction process is related to the plastic flow of the material, the second step–to the process of grain boundary diffusion and grain growth. - Highlights: • Powders were obtained by precipitation (sol–gel) method. • Ceramics were sintering by Spark Plasma Sintering method (ρ{sub rel} > 98%); shrinkage time does not exceed 8 min. • The process of ceramics sintering has two-stage character.

  5. Sintering nanodisperse zirconium powders with various stabilizing additives

    Directory of Open Access Journals (Sweden)

    Antsiferov V.N.

    2011-01-01

    Full Text Available Effect of various stabilizing additives on sintering kinetics of nanodisperse powders was studied by thermomechanical analysis. Temperature ranges of the most intense shrinking, characteristic points of shrinking rate changes were established. Peaks characterizing the most intense shrinking of nanodisperse zirconium powder samples were shown to allow to arrange the stabilizing additives as follows: Y2O3→CeO2→TiO2.

  6. Technological aspects of UO2 sintering at low temperature

    International Nuclear Information System (INIS)

    Thern, Gerardo G.; Dominguez, Carlos A.; Benitez, Ana M.; Marajofsky, Adolfo

    1999-01-01

    Within the Fuel Cycle Program of CNEA, the knowledge that plant personnel has on sintering at low temperature was evaluated, because this process could decrease costs for UO 2 and (U,Gd)O 2 pellets production, simplify the furnace maintenance and facilitate the automation of the production process, specially convenient for uranium recovery. By applying this technology, some companies have achieved production at pilot-scale and irradiated a significant number of pellets. (author)

  7. Lanthana-bearing nanostructured ferritic steels via spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Pasebani, Somayeh [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Center for Advanced Energy Studies, Idaho Falls, ID 83401 (United States); Charit, Indrajit, E-mail: icharit@uidaho.edu [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Center for Advanced Energy Studies, Idaho Falls, ID 83401 (United States); Wu, Yaqiao; Burns, Jatuporn; Allahar, Kerry N.; Butt, Darryl P. [Department of Materials Science and Engineering, Boise State University, Boise, ID 83725 (United States); Center for Advanced Energy Studies, Idaho Falls, ID 83401 (United States); Cole, James I. [Idaho National Laboratory, Idaho Falls, ID 83401 (United States); Center for Advanced Energy Studies, Idaho Falls, ID 83401 (United States); Alsagabi, Sultan F. [Department of Chemical and Materials Engineering, University of Idaho, Moscow, ID 83844 (United States); Center for Advanced Energy Studies, Idaho Falls, ID 83401 (United States)

    2016-03-15

    A lanthana-containing nanostructured ferritic steel (NFS) was processed via mechanical alloying (MA) of Fe-14Cr-1Ti-0.3Mo-0.5La{sub 2}O{sub 3} (wt.%) and consolidated via spark plasma sintering (SPS). In order to study the consolidation behavior via SPS, sintering temperature and dwell time were correlated with microstructure, density, microhardness and shear yield strength of the sintered specimens. A bimodal grain size distribution including both micron-sized and nano-sized grains was observed in the microstructure of specimens sintered at 850, 950 and1050 °C for 45 min. Significant densification occurred at temperatures greater than 950 °C with a relative density higher than 98%. A variety of nanoparticles, some enriched in Fe and Cr oxides and copious nanoparticles smaller than 10 nm with faceted morphology and enriched in La and Ti oxides were observed. After SPS at 950 °C, the number density of Cr–Ti–La–O-enriched nanoclusters with an average radius of 1.5 nm was estimated to be 1.2 × 10{sup 24} m{sup −3}. The La + Ti:O ratio was close to 1 after SPS at 950 and 1050 °C; however, the number density of nanoclusters decreased at 1050 °C. With SPS above 950 °C, the density improved but the microhardness and shear yield strength decreased due to partial coarsening of the grains and nanoparticles.

  8. Sintering of wax for controlling release from pellets

    OpenAIRE

    Singh, Reena; Poddar, S. S.; Chivate, Amit

    2007-01-01

    The purpose of the present study was to investigate incorporation of hydrophobic (ie, waxy) material into pellets using a thermal sintering technique and to evaluate the pellets in vitro for controlled release. Pellets prepared by extrusion-spheronization technology were formulated with a water-soluble drug, microcrystalline cellulose, and carnauba wax. Powdered carnauba wax (4%–20%) prepared by grinding or by emulsification was studied with an attempt to retard the drug release. The inclusio...

  9. Chemical erosion of sintered boron carbide due to H+ impact

    International Nuclear Information System (INIS)

    Davis, J.W.; Haasz, A.A.

    1990-06-01

    The production of hydrocarbons and boron hydrides due to H + bombardment of sintered B 4 C has been investigated as a function of sample temperature and incident ion energy. While hydrocarbon production was observed, the yields were approximately two orders of magnitude smaller than observed for graphite. There was no evidence to indicate the production of any volatile boron-containing compounds. (3 figs., 11 refs.)

  10. Immobilization of Uranium Silicide in Sintered Iron-Phosphate Glass

    International Nuclear Information System (INIS)

    Mateos, Patricia; Russo, Diego; Rodriguez, Diego; Heredia, A; Sanfilippo, M.; Sterba, Mario

    2003-01-01

    This work is a continuation of a previous one performed in vitrification of uranium silicide in borosilicate and iron-silicate glasses, by sintering.We present the results obtained with an iron-phosphate glass developed at our laboratory and we compare this results with those obtained with the above mentioned glasses. The main objective was to develop a method as simple as possible, so as to get a monolithic glass block with the appropriate properties to be disposed in a deep geological repository.The thermal transformation of the uranium silicide was characterized by DTA/TG analysis and X-ray diffraction.We determined the evolution of the crystalline phases and the change in weight.Calcined uranium silicide was mixed with natural U 3 O 8 , the amount of U 3 O 8 was calculated to simulate an isotopic dilution of 4%.This material was mixed with powdered iron-phosphate glass (in wt.%: 64,9 P 2 O 5 ; 22,7 Fe 2 O 3 ; 8,1 Al 2 O 3 ; 4,3 Na 2 O) in different proportions (in wt%): 7%, 10% y 15%.The powders were pressed and sintered at temperatures between 585 y 670 °C. Samples of the sintered pellet were prepared for the lixiviation tests (MCC-1P: monolithic samples; deionised water; 90° C; 7, 14 and 28 days).The samples showed a quite good durability (0,6 g.m -2 .day -1 ), similar to borosilicate glasses.The microstructure of the glass samples showed that the uranium particles are much better integrated to the glass matrix in the iron-phosphate glasses than in the borosilicate or iron-silicate glasses.We can conclude that the sintered product obtained could be a good alternative for the immobilization of nuclear wastes with high content of uranium, as the ones arising from the conditioning of research reactors spent fuels

  11. Spent fuel from nuclear research reactors immobilized in sintered glass

    International Nuclear Information System (INIS)

    Mateos, P.; Russo, D.O.; Rodriguez, D.; Heredia, A.; Sanfilippo, M.; Sterba, M.

    2002-01-01

    Different kinds of glasses, borosilicates, Iron borosilicates and Iron phosphates, were tested in order to determine its capability to immobilize calcined uranium silicide in a sintering process. Iron phosphate glass developed in our laboratory showed the best results in SEM analysis. Also its gravimetric leaching rate is less than 0.45 g.m -2 .day -1 for 7 and 10% loading which is lower than any previously studied for us. (author)

  12. Microwave-assisted sintering of non-stoichiometric strontium bismuth niobate ceramic: Structural and dielectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Rajveer [Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India); Department of Physics, Atmaram Sanatan Dharma College, University of Delhi, Dhaula Kuan, New Delhi 110021 (India); Luthra, Vandna [Department of Physics, Gargi College, University of Delhi, Siri Fort Road, New Delhi 110049 (India); Tandon, R.P., E-mail: ram_tandon@hotmail.com [Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India)

    2016-11-01

    In recent years the microwave sintering has been utilized for the synthesis of materials in enhancement of the properties. In this paper strontium bismuth niobate (Sr{sub 0.8}Bi{sub 2.2}Nb{sub 2}O{sub 9}:SBN) bulk ceramic has been synthesized by microwave reactive sintering and conventional heating techniques. A relative density of 99.6% has been achieved for microwave sintered SBN, which is higher than that of (98.81%) conventionally sintered SBN. The phase formation of SBN synthesized by both processes has been confirmed by X-ray diffraction (XRD). The surface morphology of SBN was observed by scanning electron microscopy (SEM). The microstructure was found to be more uniform in case of SBN sintered by microwave sintering. The dielectric properties of SBN were studied as a function of frequency in the temperature range of 30–500 °C. Both the samples synthesized by two different processes were found to follow Curie–Weiss law above the transition temperature. The Curie temperature was found to be higher for microwave sintered SBN. The dielectric constant and the transition temperature were observed to be higher for SBN ceramic synthesized by microwave sintering technique. The ac and dc activation energy values were also found to be higher for microwave sintered SBN as compared to conventional sintering technique.

  13. Two-step sintering of ultrafine-grained barium cerate proton conducting ceramics

    International Nuclear Information System (INIS)

    Wang, Siwei; Zhang, Lei; Zhang, Lingling; Brinkman, Kyle; Chen, Fanglin

    2013-01-01

    Ultra-fine grained dense BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3−δ (BZCYYb) ceramics have been successfully prepared via a two-step sintering method. Co-precipitation method has been adopted to prepare nano-sized BZCYYb precursors with an average particle size of 30 nm. By controlling the sintering profile, an average grain size of 184 nm was obtained for dense BZCYYb ceramics via the two-step sintering method, compared to 445 nm for the conventional sintered samples. The two-step sintered BZCYYb samples showed less impurity and an enhanced electrical conductivity compared with the conventional sintered ones. Further, the two-step sintering method was applied to fabricate anode supported solid oxide fuel cells (SOFCs) using BZCYYb as the electrolyte, resulting in dense ultrafine-grained electrolyte membranes and porous anode substrates with fine particles. Due to the reduced ohmic as well as polarization resistances, the maximum power output of the cells fabricated from the two-step sintering method reached 349 mW m −2 at 700 °C, significantly improved from 172 mW cm −2 for the conventional sintered cells, suggesting that two-step sintering method is very promising for optimizing the microstructure and thus enhancing the electrochemical performances for barium cerate based proton-conducting SOFCs.

  14. Two-step flash light sintering of copper nanoparticle ink to remove substrate warping

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Chung-Hyeon; Joo, Sung-Jun [Department of Mechanical Convergence Engineering, Hanyang University, Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Hak-Sung, E-mail: kima@hanyang.ac.kr [Department of Mechanical Convergence Engineering, Hanyang University, Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul, 133-791 (Korea, Republic of)

    2016-10-30

    Highlights: • We performed the two-step flash light sintering for copper nanoparticle ink to remove substrate warping. • 12 J/cm{sup 2} of preheating and 7 J/cm{sup 2} of main sintering energies were determined as optimum conditions to sinter the copper nanoparticle ink. • The resistivity of two-step sintered copper nanoparticle ink was 3.81 μΩ cm with 5B adhesion level, 2.3 times greater than that of bulk copper. • The two-step sintered case showed a high conductivity without any substrate warping. - Abstract: A two-step flash light sintering process was devised to reduce the warping of polymer substrates during the sintering of copper nanoparticle ink. To determine the optimum sintering conditions of the copper nanoparticle ink, the flash light irradiation conditions (pulse power, pulse number, on-time, and off-time) were varied and optimized. In order to monitor the flash light sintering process, in situ resistance and temperature monitoring of copper nanoink were conducted during the flash light sintering process. Also, a transient heat transfer analysis was performed by using the finite-element program ABAQUS to predict the temperature changes of copper nanoink and polymer substrate. The microstructures of the sintered copper nanoink films were analyzed by scanning electron microscopy. Additionally, an X-ray diffraction and Fourier transform infrared spectroscopy were used to characterize the crystal phase change of the sintered copper nanoparticles. The resulting two-step flash light sintered copper nanoink films exhibited a low resistivity (3.81 μΩ cm, 2.3 times of that of bulk copper) and 5B level of adhesion strength without warping of the polymer substrate.

  15. Sinterization of manganese ore tailings under argon atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Valduga, M.M.F.; Lima, F.; Lima, R.M.F. [Universidade Federal de Ouro Preto (UFOP), MG (Brazil)

    2014-07-01

    Manganese is an element widely used in Metallurgy, however the Brazilian reserves has low grade. The aim of this work was to obtain and characterize the sinters from manganese ore tailings. The fines (less than 400⧣) were calcinated (800°C - 3600s) and homogenized with activated charcoal (7 and 10%) and CaO (5 and 10%). The sintering were carried out at 1135, 1140 and 1145°C during 7200 and 14400s under argon atmosphere. The sintered products were characterized by EDS analysis, BET surface area, apparent density, X-rays diffraction and SEM/EDS. The surface area was 0.03m2/g. The alkali element present (potassium) justified the low melting point of waste (1140°C). Due to the chemical complexity of the tailings, several phases were characterized in the products: pores, silicates with high content of manganese in the matrix, other silicates with different proportions of Al, Mn, Mg and Ca, pure Fe, SiO2, etc. (author)

  16. Preparation and characterization of sintered Mo-Re alloys

    International Nuclear Information System (INIS)

    Morito, F.

    1993-01-01

    By the method of powder metallurgy, we have tried to fabricate Mo-Re alloys, which were electron beam weldable. Severe quality control was carried out during the whole fabrication process focused to reducing oxygen contamination. It is inevitable that the starting raw powders of Mo and Re were both high purity with 99.99 mass% up. Moreover, high vacuum sintering was performed before final sintering with high-purity hydrogen gas. As a result, we obtained electron beam weldable Mo-Re alloys, the total oxygen content of which was about 10 mass ppm or less, respectively. Several specimens were melted by electron beam welding (EBW) method. It was found that EBW gives an easy and effective survey to examine the weldability and the quality of the materials. Fracture surfaces examined by AES exhibited very low content of oxygen, carbon and nitrogen or that less than detectability limit. In conclusion, we have succeeded to obtain defect-free welds of sintered Mo-Re alloys. Furthermore it was found that Mo-Re alloys showed excellent potentialities not only in mechanical properties at low temperature but also in the respects of microstructure. (orig.)

  17. Si-substituted hydroxyapatite nanopowders: Synthesis, thermal stability and sinterability

    International Nuclear Information System (INIS)

    Bianco, Alessandra; Cacciotti, Ilaria; Lombardi, Mariangela; Montanaro, Laura

    2009-01-01

    Synthetic hydroxyapatites incorporating small amounts of Si have shown improved biological performances in terms of enhanced bone apposition, bone in-growth and cell-mediated degradation. This paper reports a systematic investigation on Si-substituted hydroxyapatite (Si 1.40 wt%) nanopowders produced following two different conventional wet methodologies: (a) precipitation of Ca(NO 3 ) 2 .4H 2 O and (b) titration of Ca(OH) 2 . The influence of the synthesis process on composition, thermal behaviour and sinterability of the resulting nanopowders is studied. Samples were characterised by electron microscopy, induced coupled plasma atomic emission spectroscopy, thermal analysis, infrared spectroscopy, N 2 adsorption measurements, X-ray diffraction and dilatometry. Semicrystalline Si-substituted hydroxyapatite powders made up of needle-like nanoparticles were obtained, the specific surface area ranged between 84 and 110 m 2 /g. Pure and Si-substituted hydroxyapatite nanopowders derived from Ca(NO 3 ) 2 .4H 2 O decomposed around 1000 deg. C. Si-substituted hydroxyapatite nanopowders obtained from Ca(OH) 2 were thermally stable up to 1200 deg. C and showed a distinct decreased thermal stability with respect to the homologous pure sample. Si-substituted hydroxyapatites exhibited higher sintering temperature and increased total shrinkage with respect to pure powders. Nanostructured dense ceramics were obtained by sintering at 1100 deg. C Si-substituted hydroxyapatites derived from Ca(OH) 2

  18. Mineralogy and microstructure of sintered lignite coal fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Marina Ilic; Christopher Cheeseman; Christopher Sollars; Jonathan Knight [Faculty of Technology and Metallurgy, Belgrade (Yugoslavia)

    2003-02-01

    Lignite coal fly ash from the 'Nikola Tesla' power plant in Yugoslavia has been characterised, milled, compacted and sintered to form monolithic ceramic materials. The effect of firing at temperatures between 1130 and 1190{sup o}C on the density, water accessible porosity, mineralogy and microstructure of sintered samples is reported. This class C fly ash has an initial average particle size of 82 {mu}m and contains siliceous glass together with the crystalline phases quartz, anorthite, gehlenite, hematite and mullite. Milling the ash to an average particle size of 5.6 m, compacting and firing at 1170{sup o}C for 1 h produces materials with densities similar to clay-based ceramics that exhibit low water absorption. Sintering reduces the amount of glass, quartz, gehlenite and anhydrite, but increases formation of anorthite, mullite, hematite and cristobalite. SEM confirms the formation of a dense ceramic at 1170{sup o}C and indicates that pyroplastic effects cause pore formation and bloating at 1190{sup o}C. 23 refs., 6 figs., 2 tabs.

  19. PRODUCTION OF PROTOTYPE PARTS USING DIRECT METAL LASER SINTERING TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Josef Sedlak

    2015-08-01

    Full Text Available Unconventional methods of modern materials preparation include additive technologies which involve the sintering of powders of different chemical composition, granularity, physical, chemical and other utility properties. The technology called Rapid Prototyping, which uses different technological principles of producing components, belongs to this type of material preparation. The Rapid Prototyping technology facilities use photopolymers, thermoplastics, specially treated paper or metal powders. The advantage is the direct production of metal parts from input data and the fact that there is no need for the production of special tools (moulds, press tools, etc.. Unused powder from sintering technologies is re-used for production 98% of the time, which means that the process is economical, as well as ecological.The present paper discusses the technology of Direct Metal Laser Sintering (DMLS, which falls into the group of additive technologies of Rapid Prototyping (RP. The major objective is a detailed description of DMLS, pointing out the benefits it offers and its application in practice. The practical part describes the production and provides an economic comparison of several prototype parts that were designed for testing in the automotive industry.

  20. Highly textured KNN-based piezoelectric ceramics by conventional sintering

    International Nuclear Information System (INIS)

    Zapata, Angelica Maria Mazuera; Silva Junior, Paulo Sergio da; Zambrano, Michel Venet

    2016-01-01

    Full text: Texturing in ferroelectric ceramics has played an important role in the enhancement of their piezoelectric properties. Common methods for ceramic texturing are hot pressing and template grain ground; nevertheless, the needed facilities to apply hot pressing and the processing of single crystal make the texture of ceramics expensive and very difficult. In this study, a novel method was investigated to obtain highly textured lead-free ceramics. A (K 0.5 Na 0.5 ) 0.97 Li 0. 0 3 Nb 0.8 Ta 0. 2 matrix (KNLNT), with CuO excess was sintered between 1070 and 1110 °C following a solid state reaction procedure. The CuO excess promotes liquid phase formation and a partial melting of the material. XRD patterns showed the intensity of (100) family peaks became much stronger with the increasing of sintering temperature and CuO. In addition, Lotgering factor was calculated and exhibited a texture degree between 40 % and 70 % for sintered samples having 13 and 16 wt. % CuO, respectively. These, highly textured ceramics, with adequate cut, can be used as substitutes single crystals for texturing of KNN-based lead-free ceramics. (author)

  1. Spark plasma sintering and porosity studies of uranium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Kyle D., E-mail: kylej@kth.se; Wallenius, Janne; Jolkkonen, Mikael; Claisse, Antoine

    2016-05-15

    In this study, a number of samples of UN sintered by the SPS method have been fabricated, and highly pure samples ranging in density from 68% to 99.8%TD – corresponding to an absolute density of 14.25 g/cm{sup 3} out of a theoretical density of 14.28 g/cm{sup 3} – have been fabricated. By careful adjustment of the sintering parameters of temperature and applied pressure, the production of pellets of specific porosity may now be achieved between these ranges. The pore closure behaviour of the material has also been documented and compared to previous studies of similar materials, which demonstrates that full pore closure using these methods occurs near 97.5% of relative density. - Highlights: • UN pellets are fabricated over a wide array of densities using the SPS method. • The sintereing parameters necessary to produce pellets over a wide array of density space are charted. • Pellets of extremely high density (99.9% of TD, absolute density of 14.25 g/cm{sup 3}) are fabricated. • Full-closure of the porosity in this material is obtained at around 2.5% of total porosity.

  2. Adjustment of Part Properties for an Elastomeric Laser Sintering Material

    Science.gov (United States)

    Wegner, A.; Ünlü, T.

    2018-03-01

    Laser sintering of polymers is gaining more and more importance within the field of small series productions. Polyamide 12 is predominantly used, although a variety of other materials are also available for the laser sintering process. For example, elastomeric, rubberlike materials offer very different part property profiles. Those make the production of flexible parts like, e.g., sealings, flexible tubes or shoe soles possible because they offer high part ductility and low hardness. At the chair for manufacturing technology, a new elastomeric laser sintering material has been developed and then commercialized by a spin-off from university. The aim of the presented study was the analysis of the new material's properties. Proof was found that Shore hardness can be modified by varying the parameter settings. Therefore, the correlation between process parameters, energy input, Shore hardness and other part properties like mechanical properties were analyzed. Based on these results, suitable parameter settings were established which lead to the possibility of producing parts with different Shore hardnesses.

  3. Solvent/Non-Solvent Sintering To Make Microsphere Scaffolds

    Science.gov (United States)

    Laurencin, Cato T.; Brown, Justin L.; Nair, Lakshmi

    2011-01-01

    A solvent/non-solvent sintering technique has been devised for joining polymeric microspheres to make porous matrices for use as drug-delivery devices or scaffolds that could be seeded with cells for growing tissues. Unlike traditional sintering at elevated temperature and pressure, this technique is practiced at room temperature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more reproducible than are properties of comparable scaffolds made by traditional sintering. The technique involves the use of two miscible organic liquids: one that is and one that is not a solvent for the affected polymer. The polymeric microspheres are placed in a mold having the size and shape of the desired scaffold, then the solvent/non-solvent mixture is poured into the mold to fill the void volume between the microspheres, then the liquid mixture is allowed to evaporate. Some of the properties of the resulting scaffold can be tailored through choice of the proportions of the liquids and the diameter of the microspheres.

  4. Sintering mechanism of blast furnace slag-kaolin ceramics

    International Nuclear Information System (INIS)

    Mostafa, Nasser Y.; Shaltout, Abdallah A.; Abdel-Aal, Mohamed S.; El-maghraby, A.

    2010-01-01

    A general ceramics processing scheme by cold uniaxial pressing and conventional sintering process have been used to prepare ceramics from mixtures of blast furnace slag (BFS) and kaolin (10%, 30% and 50% kaolin). The properties of the ceramics were studied by measuring linear shrinkage, bulk density, apparent porosity and mechanical properties of samples heated at temperatures from 800 o C to 1100 o C. The formed crystalline phases were characterized using X-ray diffraction (XRD) and scanning electron microscope (SEM). Slag melt formed at relatively low temperatures (800-900 o C) modified the sintering process to liquid phase sintering mechanism. Combination of BFS with 10% kaolin gave the highest mechanical properties, densification and shrinkage at relatively low firing temperatures. The crystalline phases were identified as gehlenite (Ca 2 Al 2 SiO 7 ) in both BFS and BFS with 10% kaolin samples. Anorthite (CaAl 2 Si 2 O 8 ) phase increased with increasing kaolin contents. In the case of kaolin-rich mixtures (30% and 50% kaolin), increased expansion took place during firing at temperatures in the range 800-1000 o C. This effect could be attributed to the entrapment of released gases.

  5. Fast Convolution Module (Fast Convolution Module)

    National Research Council Canada - National Science Library

    Bierens, L

    1997-01-01

    This report describes the design and realisation of a real-time range azimuth compression module, the so-called 'Fast Convolution Module', based on the fast convolution algorithm developed at TNO-FEL...

  6. Preparation and sintering of Zr(C,N,O) phases

    International Nuclear Information System (INIS)

    Tamborenea, S.; Mazzoni, A.D.; Aglietti, E.F.

    2003-01-01

    The Zr(C,O,N) compounds form a great mono-phase zone belonging to the pseudoternary ZrO-ZrN-ZrC system.Theses phases have cubic crystalline structure with a o parameter depending on the C, O 2 and N 2 content.These phases have many potential applications in the manufacture of ceramic pieces utilizable as electronic conductors.The Zr (C,O,N) phases can be obtained from ZrO 2 by carbonitriding reactions: that is carbothermal reduction and simultaneous nitriding.In this work a series of experiences of carbonitriding of zirconia under different conditions (temperatures between 1400 and 1600degC, times of 120 min, carbon content between 20 and 40%) in order to obtain suitable powders to be sintered.The XRD analysis shows the Zr(C,O,N) as the main products and β -ZrON as the only secondary product in proportions depending on the obtaining conditions.The variables employed were the C content and the reaction temperature.The Zr(C,O,N) content varies between 40 and 90% and tends to increase with the temperature and the carbon content whereas the β -ZrON phase varies between the 40 and 10 % decreasing its proportion with temperature and the carbon content.The oxidation resistance of these phases was studied by DTA-TG tests in air.Results show complete oxidation reaction at ∼500degC in air.The sintering of these materials was made on disks obtained by pressing of powders of Zr(C,N,O) contents higher than 90%.Sintering was performed in nitrogen atmosphere and temperatures between 1450 and 1620degC.Disks were characterized by pycnometry and Hg volumeter.The densities obtained were between 5 and 6,6g/cm 3 with a tendency to increase with the Zr(C,N,O) phase content, the temperature and the sintering time.Sintered disks were characterized by dilatometry in N 2

  7. Manufacture of core sub-assemblies and fertile fuel assemblies for Indian fast breeder programme

    International Nuclear Information System (INIS)

    Jayaraj, R.N.

    2009-01-01

    Full text: Utilization of the vast reserves of thorium in the Fast Reactors has been the prime goal of nuclear power programme in India. Nuclear Fuel Complex (NFC) has successfully fabricated axial and radial blanket assemblies for the Fast Breeder Test Reactor (FBTR) containing thoria. Development of technologies for the manufacture of thoria pellets involved characterization of powder obtained by oxalate precipitation and calcination with the addition of small quantities of magnesium during oxalate precipitation. This has resulted in achieving desired sintered densities. Though the magnesia doped thoria has yielded specified densities by sintering the pellets at ∼1600 deg. C, experimental works on activated sintering of the thoria powders containing small quantities of Nb 2 O 5 has yielded similar densities when sintered in air at much lower temperatures. Doping of ThO 2 by Nb 2 O 5 is expected to give rise to oxygen interstitials or vacancies. A higher valency additive like Nb 2 O 5 and an oxidizing atmosphere has resulted in substantially lowering the sintering temperature while a lower valency additive and a reducing sintering atmosphere requires higher sintering temperature. Increase in the diffusion coefficient of thorium is likely to be responsible for activated sintering. Several experimental works on compaction of thoria powder revealed that the desired green density could be achieved at a moderate pressure of 140 MPa. An increase in inter-particle contact is evident by an increase in the green density and also in the specific surface area as the compaction pressure is increased. The compactability and sinterability characteristics seem to be affected by long storage of powder. Ball milling of powder prior to pre-compaction and granulation is found, in addition to breaking the agglomerates, to restore the original characteristics of the powder. The technique of thermal etching has been successfully used for examining the microstructural features of

  8. In-situ anatase phase stabilization of titania photocatalyst by sintering in presence of Zr4+ organic salts

    Science.gov (United States)

    Strini, Alberto; Sanson, Alessandra; Mercadelli, Elisa; Bendoni, Riccardo; Marelli, Marcello; Dal Santo, Vladimiro; Schiavi, Luca

    2015-08-01

    The direct in-situ stabilization of an anatase-based nanocrystalline photocatalyst (Degussa P25) was obtained by sintering the catalyst powder in presence of Zr4+ organic salts. This approach allows the doping of an already-formed nanocrystalline photocatalyst instead of introducing the dopant in the crystal lattice during the catalyst synthesis. The procedure was demonstrated by the production of thick ceramic layers using the screen printing technique. This new method allows to easily stabilize the anatase phase 200 °C higher than the undoped P25 maintaining the same photocatalytic activity. The process was studied using specifically formulated screen-printing inks added with Zr4+ organic salt at 1% and 2% Zr/Ti molar ratio. The anatase phase stability was investigated in the 500-900 °C temperature range analysing the resulting catalysts with XRD, TEM and (S)TEM-EDS. The catalytic activity of the screen-printed layers was assessed by measuring the degradation of toluene in air at ambient concentration (500 nmol m-3) and low UV-A irradiance (180 μW cm-2). The described in-situ stabilization method could be potentially applied to any deposition process involving already formed anatase photocatalyst, allowing higher sintering temperature and then an improved mechanical stability of the active layers without photocatalytic activity degradation.

  9. A comparative study on NbOx films reactively sputtered from sintered and cold gas sprayed targets

    Science.gov (United States)

    Lorenz, Roland; O'Sullivan, Michael; Fian, Alexander; Sprenger, Dietmar; Lang, Bernhard; Mitterer, Christian

    2018-04-01

    The aim of this work is to evaluate novel cold gas sprayed Nb targets in a reactive sputter deposition process of thin films with respect to the widely used sintered Nb targets. With the exception of a higher target discharge voltage of ∼100 V for the cold gas sprayed targets and the thus higher film growth rate compared to sintered targets, NbOx films with comparable microstructure and properties were obtained for both target variants. The amorphous films with thicknesses between 2.9 and 4.9 μm present an optical shift from dark and non-transparent towards transparent properties, as the oxygen partial pressure increases. X-ray photoelectron spectroscopy confirms the occurrence of the Nb5+ oxidation state for the highest oxygen partial pressure, while Nb4+ is additionally present at lower oxygen partial pressure settings. With a maximal transparency of ∼80% and a refractive index of ∼2.5, the transparent films show characteristics similar to Nb2O5.

  10. FAST: FAST Analysis of Sequences Toolbox

    Directory of Open Access Journals (Sweden)

    Travis J. Lawrence

    2015-05-01

    Full Text Available FAST (FAST Analysis of Sequences Toolbox provides simple, powerful open source command-line tools to filter, transform, annotate and analyze biological sequence data. Modeled after the GNU (GNU’s Not Unix Textutils such as grep, cut, and tr, FAST tools such as fasgrep, fascut, and fastr make it easy to rapidly prototype expressive bioinformatic workflows in a compact and generic command vocabulary. Compact combinatorial encoding of data workflows with FAST commands can simplify the documentation and reproducibility of bioinformatic protocols, supporting better transparency in biological data science. Interface self-consistency and conformity with conventions of GNU, Matlab, Perl, BioPerl, R and GenBank help make FAST easy and rewarding to learn. FAST automates numerical, taxonomic, and text-based sorting, selection and transformation of sequence records and alignment sites based on content, index ranges, descriptive tags, annotated features, and in-line calculated analytics, including composition and codon usage. Automated content- and feature-based extraction of sites and support for molecular population genetic statistics makes FAST useful for molecular evolutionary analysis. FAST is portable, easy to install and secure thanks to the relative maturity of its Perl and BioPerl foundations, with stable releases posted to CPAN. Development as well as a publicly accessible Cookbook and Wiki are available on the FAST GitHub repository at https://github.com/tlawrence3/FAST. The default data exchange format in FAST is Multi-FastA (specifically, a restriction of BioPerl FastA format. Sanger and Illumina 1.8+ FastQ formatted files are also supported. FAST makes it easier for non-programmer biologists to interactively investigate and control biological data at the speed of thought.

  11. The Effects of Solid Phase Additives on Sintering Properties of Alumina Bioceramic

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-yu; LI Shi-pu; HE Jian-hua; JIANG Xin; LI Jian-hua

    2003-01-01

    In order to reduce the sintering temperature and improve the preparing conditions of alumina bioceramics,the Mg-Zr-Y composite solid phase additives were added into high purity Al2O3 micro-powder by chemical coprecipitation method.The powder was shaped under 200MPa cold isostatic pressure,and then the biscuits were sintered at 1600℃ under normal pressure.The sintered alumina materials were tested and the sintering mechanism was discussed.The results show that physical properties of the material were improved comparatively.The Mg-Zr-Y composite solid additives could promote the sintering of alumina bioceramics and the mechanism is solid phase sintering.

  12. Addition of niobia in alumina and its effects at its sintered microstructure

    International Nuclear Information System (INIS)

    Gomes, L.B.; Lima, M.M.O.; Pereira, A.S.; Bergmann, C.P.

    2016-01-01

    In this work, niobia was used as sintering additive of alumina in concentrations of 0.15, 0.5, 2 and 4 wt%. Homogenized powders was uniaxially pressed (200MPa) forming ceramic pellets with 10 mm diameter. The green bodies were sintered at 1400, 1500 and 1600°C for 60 minutes using a heating rate of 2,5°C.min -1 . After sintering, the specimens were polished using diamond paste with different particle sizes. The specimen's microstructure was analyzed by Scanning Electron Microscopy (SEM) and crystalline phases were determined by X-ray Diffraction (XRD). Results indicate that when niobia and alumina react they form AlNbO4 by liquid phase sintering. This phase is located among alumina grain. It was also verified that niobia addition promotes grain growth, acting as sintering agent, and this effect grows as niobia content and sintering temperature increase. (author)

  13. Process parameter influence on Electro-sinter-forging (ESF) of titanium discs

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Chris Valentin; Bay, Niels

    Electro-sinter-forging (ESF) is an innovative sintering process based on the principle of electrical Joule heating. The electrical current is flowing through the powder compact, which is under mechanical pressure. As compared to conventional sintering [1] and spark plasma sintering [2], the main...... advantages are the decreased sintering time and high relative density [3]. Near net-shape components can be manufactured and post-removal processing is limited to surface polishing. The present work is focused on analysing the influence of the main process parameters, namely compacting pressure, sintering...... time and electrical current density, on the final density of a disc sample made from commercially pure titanium powder. The maximum achieved relative density was 94% of the bulk density of pure titanium. The density estimation was carried out by using both Archimedes’ and 3D scanning....

  14. Investigation of the Sintering Process Using Non-Contact Electromagnetic Acoustic Transducers

    International Nuclear Information System (INIS)

    James C. Foley; David K. Rehbein; Daniel J. Barnard

    2001-01-01

    In-situ characterizations of green state part density and sintering state have long been desired in the powder metal community. Recent advances in non-contact electromagnetic acoustic transducer (EMAT) technology have enabled in-situ monitoring of acoustic amplitude and velocity as sintering proceeds. Samples were made from elemental powders of Al (99.99%), Al (99.7%), Ag, (99.99%), Cu (99.99%) and Fe (99.9%). The powders were pressed in a uniaxial die and examined with acoustic waves for changes in velocity and amplitude during sintering for the samples containing Al, Ag, and Cu. The changes in acoustic properties were correlated with sample microstructures and mechanical properties. Evolution of a series of reverberating echoes during sintering is shown to provide information on the state of sintering, and changes in sintering kinetics as well as having the potential for detection of interior flaws

  15. Effects of sintering temperature on electrical properties of sheep enamel hydroxyapatite

    Science.gov (United States)

    Dumludag, F.; Gunduz, O.; Kılıc, O.; Kılıc, B.; Ekren, N.; Kalkandelen, C.; Oktar, F. N.

    2017-12-01

    Bioceramics, especially calcium phosphate based bioceramics, whose examples are hydroxyapatite, and calcium phosphate powders have been widely used in the biomedical engineering applications. Hydroxyapatite (HA) is one of the most promising biomaterials, which are derived from natural sources, chemical method, animal like dental enamel and corals. The influence of sintering temperature on the electrical properties (i.e. DC conductivity, AC conductivity) of samples of sintered sheep enamel (SSSE) was studied in air and in vacuum ambient at room temperature. The sheep enamel were sintered at varying temperatures between 1000°C and 1300°C. DC conductivity results revealed that while dc conductivity of the SSSE decreases with increasing the sintering temperature in air ambient the values increased with increasing the sintering temperature in vacuum ambient. AC conductivity measurements were performed in the frequency range of 40 Hz - 105 Hz. The results showed that ac conductivity values decrease with increasing the sintering temperature.

  16. One step sintering of homogenized bauxite raw material and kinetic study

    Science.gov (United States)

    Gao, Chang-he; Jiang, Peng; Li, Yong; Sun, Jia-lin; Zhang, Jun-jie; Yang, Huan-ying

    2016-10-01

    A one-step sintering process of bauxite raw material from direct mining was completed, and the kinetics of this process was analyzed thoroughly. The results show that the sintering kinetics of bauxite raw material exhibits the liquid-phase sintering behavior. A small portion of impurities existed in the raw material act as a liquid phase. After X-ray diffraction analyses, scanning electron microscopy observations, and kinetics calculations, sintering temperature and heating duration were determined as the two major factors contributing to the sintering process and densification of bauxite ore. An elevated heating temperature and longer duration favor the densification process. The major obstacle for the densification of bauxite material is attributed to the formation of the enclosed blowhole during liquid-phase sintering.

  17. The physical chemistry and materials science behind sinter-resistant catalysts.

    Science.gov (United States)

    Dai, Yunqian; Lu, Ping; Cao, Zhenming; Campbell, Charles T; Xia, Younan

    2018-06-18

    Catalyst sintering, a main cause of the loss of catalytic activity and/or selectivity at high reaction temperatures, is a major concern and grand challenge in the general area of heterogeneous catalysis. Although all heterogeneous catalysts are inevitably subjected to sintering during their operation, the immediate and drastic consequences can be mitigated by carefully engineering the catalytic particles and their interactions with the supports. In this tutorial review, we highlight recent progress in understanding the physical chemistry and materials science involved in sintering, including the discussion of advanced techniques, such as in situ microscopy and spectroscopy, for investigating the sintering process and its rate. We also discuss strategies for the design and rational fabrication of sinter-resistant catalysts. Finally, we showcase recent success in improving the thermal stability and thus sinter resistance of supported catalytic systems.

  18. Corneal thickness: measurement and implications.

    Science.gov (United States)

    Ehlers, Niels; Hjortdal, Jesper

    2004-03-01

    The thickness of the cornea was reported in more than 100-year-old textbooks on physiological optics (Helmholtz, Gullstrand). Physiological interest was revived in the 1950s by David Maurice, and over the next 50 years, this 'simple' biological parameter has been studied extensively. Several techniques for its measurement have been described and physiological and clinical significance have been studied. In this review, the different methods and techniques of measurement are briefly presented (optical, ultrasound). While the corneal thickness of many animals are the same over a considerable part of the surface, in the human cornea anterior and posterior curvature are not concentric giving rise to a problem of definition. Based on this the precision and accuracy of determining the central corneal thickness are discussed. Changes in corneal thickness reflects changes in function of the boundary layers, in particular the endothelial barrier. The absolute value of thickness is of importance for the estimation of IOP but also in diagnosis of corneal and systemic disorders. Finally it is discussed to what extent the thickness is a biometric parameter of significance, e.g. in the progression of myopia or in the development of retinal detachment.

  19. Fracture toughness of yttria-stabilized zirconia sintered in conventional and microwave ovens.

    Science.gov (United States)

    Marinis, Aristotelis; Aquilino, Steven A; Lund, Peter S; Gratton, David G; Stanford, Clark M; Diaz-Arnold, Ana M; Qian, Fang

    2013-03-01

    The fabrication of zirconium dioxide (ZrO2) dental prosthetic substructures requires an extended sintering process (8 to 10 hours) in a conventional oven. Microwave sintering is a shorter process (2 hours) than conventional sintering. The purpose of this study was to compare the fracture toughness of 3 mol % Y2O3-stabilized ZrO2 sintered in a conventional or microwave oven. Partially sintered ZrO2 specimens from 3 manufacturers, KaVo, Lava 3M, and Crystal HS were milled (KaVo Everest engine) and randomly divided into 2 groups: conventional sintering and microwave sintering (n=16 per group). The specimens were sintered according to the manufacturers' recommendations and stored in artificial saliva for 10 days. Fracture toughness was determined by using a 4-point bend test, and load to fracture was recorded. Mean fracture toughness for each material was calculated. A 2-way ANOVA followed by the Tukey HDS post hoc test was used to assess the significance of sintering and material effects on fracture toughness, including an interaction between the 2 factors (α=.05). The 2-way ANOVA suggested a significant main effect for ZrO2 manufacturer (P.05). The main effect of the sintering process (Conventional [5.30 MPa·m(1/2) ±1.00] or Microwave [5.36 MPa·m(1/2) ±0.92]) was not significant (P=.76), and there was no interaction between sintering and ZrO2 manufacturer (P=.91). Based on the results of this study, no statistically significant difference was observed in the fracture toughness of ZrO2 sintered in microwave or conventional ovens. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  20. Sintering of Spherical Particles of Equal and Different Size Arranged in a Body Centered Cubic Structure

    DEFF Research Database (Denmark)

    Redanz, Pia; McMeeking, R. M.

    2003-01-01

    Solid-state sintering of a bcc structure of spherical particles has been studied numerically by use of simple shape parameters to describe the state of the unit cell. Both free and pressure-assisted sintering of particles of equal and different sizes for various ratios of boundary and surface dif......, different dihedral angles and the evolution of relative density and sintering stresses are studied....

  1. Spark plasma sintering of SiC and ZrC

    Energy Technology Data Exchange (ETDEWEB)

    Guillard, F.; Galy, J. [CEMES-CNRS, 29 rue Jeanne Marvig BP94347 31055 Toulouse Cx 4 (France); Allemand, A. [CEA Saclay, DRT/DTEN/S3ME/LTMEx, 91191 Gif-sur-Yvette (France)

    2005-07-01

    Spark plasma sintering a relative new technique allows sintering material powders in a reduced time compared to formal process of densification. In order to analyse densification mechanisms and to compare with hot isostatic pressing technique, pellets of silicon carbide and zirconium carbide were sintered by HIP and by SPS from 1750 to 1950 deg. C, with different pressures (50 to 75 MPa) and various holding times (0 to 10 min). Their densities were determined and their microstructures were SEM analysed. (authors)

  2. Sintering of MSW fly ash for reuse as a concrete aggregate.

    Science.gov (United States)

    Mangialardi, T

    2001-10-12

    The sintering process of municipal solid waste (MSW) fly ash was investigated in order to manufacture sintered products for reuse as concrete aggregates. Four types of fly ash resulting from different Italian MSW incineration plants were tested in this study. A modification of the chemical composition of MSW fly ash--through a preliminary four-stage washing treatment of this material with water--was attempted to improve the chemical and mechanical characteristics of sintered products.The sintering treatment of untreated or washed fly ash was performed on cylindrical compact specimens (15 mm in diameter and 20mm in height) at different compact pressures, sintering temperatures and times.The sintering process of untreated MSW fly ashes proved to be ineffective for manufacturing sintered products for reuse as a construction material, because of the adverse chemical characteristics of these fly ashes in terms of sulfate, chloride, and vitrifying oxide contents.A preliminary washing treatment of MSW fly ash with water greatly improved the chemical and mechanical characteristics of sintered products and, for all the types of fly ash tested, the sintered products satisfied the Italian requirements for normal weight aggregates for use in concretes having a specified strength not greater than 12 and 15N/mm(2), when measured on cylindrical and cubic specimens, respectively.A compact pressure of 28 N/mm(2), a sintering temperature of 1140 degrees C, and a sintering time of 60 min were the best operating conditions for manufacturing sintered products of washed MSW fly ash.

  3. The effect of various sintering temperature on used refractory towards its physical properties

    Science.gov (United States)

    Sudibyo; Wulandari, Y. R.; Amin, M.; Azhar

    2018-01-01

    The used magnesia refractory from the kiln of cement industry was successfully recycled to new refractory using Kaolin as an adhesive. In this work, the temperatures of sintering were varied from 1000°C to 1500°C. The result shows that the increment temperature effects in sintering process will enhance refractory physical properties such as bulk density, cold crushing strength or pressure strength and thermal conductivity. Meanwhile, the porosity was decreased as the increase of the sintering temperature.

  4. Initial results of a high-power microwave sintering experiment at ORNL

    International Nuclear Information System (INIS)

    Kimrey, H.D.; White, T.L.; Bigelow, T.S.; Becher, P.F.

    1986-01-01

    Experiments have recently begun at Oak Ridge National Laboratory to develop microwave sintering techniques suitable for large ceramic parts. Microwave sintering offers the advantages of faster heating rates, more uniform heating, and greater energy efficiency than conventional sintering techniques. We are using 28-GHz, 200-kW cw gyrotrons as the heating source. An untuned cavity is used as the applicator to eliminate geometry sensitivity in coupling efficiency

  5. The influence of green microstructure and sintering parameters on precipitation process during copper-nickel-zinc ferrites sintering

    Directory of Open Access Journals (Sweden)

    Barba, Antonio

    2014-04-01

    Full Text Available Microstructural changes that occur during heat treatment of copper-nickel-zinc ferrites have been studied. The process of precipitation of the two types of crystals that occur during the sintering process has been analyzed. It is found that this process depends on dry relative density of the press specimens and on the following sintering parameters: sintering temperature, sintering time and cooling rate of the thermal cycle. Crystal precipitates characterization have been done by scanning electron microscopy (SEM, energy-dispersive X-ray (EDX analysis, X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS. These techniques have allowed to determine the nature of these crystals, which in this case correspond to zinc and copper oxides. It has been used two chemical reactions to explain the bulk precipitation and subsequent re-dissolution of these crystal precipitates during sintering.En este trabajo se han estudiado los cambios microestructurales que se producen durante el tratamiento térmico de las ferritas de cobre-níquel-cinc y se ha analizado el proceso de precipitación de los dos tipos de cristales que aparecen durante el proceso de sinterización. Se ha encontrado que este proceso depende de la densidad relativa en seco de las muestras compactadas y de las siguientes variables de la etapa de sinterización: temperatura y tiempo de sinterización y velocidad de enfriamiento. La caracterización de los cristales precipitados se ha realizado por microscopía electrónica de barrido (MEB, microanálisis por dispersión de energía de rayos X (EDX, difracción de rayos X (DRX, y espectroscopía de fotoelectrones de rayos X (XPS. Estas técnicas han permitido determinar la naturaleza de estos cristales, que en este caso corresponden a los óxidos de cinc y de cobre. Se han propuesto dos reacciones químicas que permiten explicar el proceso de precipitación y la posterior re-disolución de estos cristales precipitados durante la

  6. The effect of lanthanum boride on the sintering, sintered microstructure and mechanical properties of titanium and titanium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y.F. [RMIT University, Centre for Additive Manufacturing, School of Aerospace, Mechanical and Manufacturing Engineering, GPO Box 2476, Melbourne VIC 3001 (Australia); Luo, S.D. [The University of Queensland, School of Mechanical and Mining Engineering, Brisbane, QLD 4072 (Australia); Qian, M., E-mail: ma.qian@rmit.edu.au [RMIT University, Centre for Additive Manufacturing, School of Aerospace, Mechanical and Manufacturing Engineering, GPO Box 2476, Melbourne VIC 3001 (Australia)

    2014-11-17

    An addition of ≤0.5 wt% lanthanum boride (LaB{sub 6}) to powder metallurgy commercially pure Ti (CP-Ti), Ti–6Al–4V and Ti–10V–2Fe–3Al (all in wt%) resulted in improved sintered density, substantial microstructural refinement, and noticeably increased tensile elongation. The addition of LaB{sub 6} led to scavenging of both oxygen (O) and chlorine (Cl) from the titanium powder during sintering, evidenced by the formation of La{sub 2}O{sub 3} and LaCl{sub x}O{sub y}. The pinning effect of La{sub 2}O{sub 3}, LaCl{sub x}O{sub y} and TiB inhibited prior-β grain growth and resulted in subsequent smaller α-laths. The formation of nearly equiaxed α-Ti phase is partially attributed to the nucleation effect of α-Ti on TiB. The improved sintered density was caused by B from LaB{sub 6} rather than La, while excessive formation of La{sub 2}O{sub 3} and TiB with an addition of >0.5 wt% LaB{sub 6} resulted in a noticeable decrease in sintered density. The improved tensile elongation with an addition of ≤0.5 wt% LaB{sub 6} was mainly attributed to the scavenging of oxygen by LaB{sub 6}, partially assisted by the improved sintered density. However, an addition of >0.5 wt% LaB{sub 6} led to the formation of large La{sub 2}O{sub 3} aggregates and more brittle TiB whiskers and therefore decreased tensile elongation. Balanced scavenging of O is thus important. The optimal addition of LaB{sub 6} was 0.5 wt% but this may change depending on the powder size of the LaB{sub 6} to be used.

  7. Strengthening mechanisms in a high-strength bulk nanostructured Cu–Zn–Al alloy processed via cryomilling and spark plasma sintering

    International Nuclear Information System (INIS)

    Wen, Haiming; Topping, Troy D.; Isheim, Dieter; Seidman, David N.; Lavernia, Enrique J.

    2013-01-01

    A bulk nanostructured alloy with the nominal composition Cu–30Zn–0.8Al wt.% (commercial designation brass 260) was fabricated by cryomilling of brass powders and subsequent spark plasma sintering (SPS) of the cryomilled powders, yielding a compressive yield strength of 950 MPa, which is significantly higher than the yield strength of commercial brass 260 alloys (∼200–400 MPa). Transmission electron microscopy investigations revealed that cryomilling results in an average grain diameter of 26 nm and a high density of deformation twins. Nearly fully dense bulk samples were obtained after SPS of cryomilled powders, with average grain diameter 110 nm. After SPS, 10 vol.% of twins is retained with average twin thickness 30 nm. Three-dimensional atom-probe tomography studies demonstrate that the distribution of Al is highly inhomogeneous in the sintered bulk samples, and Al-containing precipitates including Al(Cu,Zn)–O–N, Al–O–N and Al–N are distributed in the matrix. The precipitates have an average diameter of 1.7 nm and a volume fraction of 0.39%. Quantitative calculations were performed for different strengthening contributions in the sintered bulk samples, including grain boundary, twin boundary, precipitate, dislocation and solid-solution strengthening. Results from the analyses demonstrate that precipitate and grain boundary strengthening are the dominant strengthening mechanisms, and the calculated overall yield strength is in reasonable agreement with the experimentally determined compressive yield strength

  8. [The effect of core veneer thickness ratio on the flexural strength of diatomite-based dental ceramic].

    Science.gov (United States)

    Jiang, Jie; Zhang, Xin; Gao, Mei-qin; Zhang, Fei-min; Lu, Xiao-li

    2015-06-01

    To evaluate the effect of different core veneer thickness ratios on the flexural strength and failure mode of bilayered diatomite-based dental ceramics. Diatomite-based dental ceramics blocks (16 mm×5.4 mm×1 mm) were sintered with different thickness of veneer porcelains: 0 mm (group A), 0.6 mm (group B), 0.8 mm (group C) and 1.0 mm (group D). Flexural strength was detected and scanning electron microscope was used to observe the interface microstructure. Statistical analysis was performed using SPSS 17.0 software package. With the increase of the thickness of the veneer porcelain, flexural strength of group C showed highest flexural strength up to (277.24±5.47) MPa. Different core veneer thickness ratios can significantly influence the flexural strength of bilayered diatomite-based dental ceramics. Supported by Science and Technology Projects of Nantong City (HS2013010).

  9. Enhanced pressureless bonding by Tin Doped Silver Paste at low sintering temperature

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Cheng-Xiang [School of Material Science and Engineering, and Tianjin Key Laboratory of Advanced Joining Technology, Tianjin University, Tianjin (China); Department of Material Science and Engineering, Virginia Tech (United States); Li, Xin, E-mail: xinli@tju.edu.cn [School of Material Science and Engineering, and Tianjin Key Laboratory of Advanced Joining Technology, Tianjin University, Tianjin (China); Lu, Guo-Quan [School of Material Science and Engineering, and Tianjin Key Laboratory of Advanced Joining Technology, Tianjin University, Tianjin (China); Department of Material Science and Engineering, Virginia Tech (United States); Mei, Yun-Hui [School of Material Science and Engineering, and Tianjin Key Laboratory of Advanced Joining Technology, Tianjin University, Tianjin (China)

    2016-04-13

    The nanosilver sintering die-attach technique has been a promising alternative for wide band gap semiconductors. However, it is less preferable in industry because of its high sintering temperature. Recently research has been initiated to develop transient liquid phase sintering (TLPS) solder paste for use in electronics packaging. In this article, in order to lower the sintering temperature of nanosilver paste, we develop a novel tin (up to 10 wt%) doped silver paste (TDSP) and a sintering profile with the highest processing temperature of 235 °C based on TLPS. Sintered TDSP is Ag/Ag{sub 3}Sn/Ag–Sn solid solution composites. The composites have a microstructure of Ag matrix grains reinforced by Ag{sub 3}Sn and Ag–Sn solid solution within the matrix grains. And this microstructure endows the sintered Ag+4%Sn with a pressureless bonding strength of 23 MPa. The improved mechanical properties of sintered TDSP are attributed to second-phase strengthening and solid solution strengthening mechanisms. However, the overmuch formation of brittle Ag{sub 3}Sn phase is the main reason resulting in sharp decrease of bonding strength when the Sn content over 5 wt%. The new TDSP technology is expected to be applicable to a wide range of power semiconductors devices, such as organic devices and printed circuit boards. Furthermore, it provides new strategies for low-temperature sintering.

  10. Preparation of silicon carbide/carbon fiber composites through high-temperature spark plasma sintering

    Directory of Open Access Journals (Sweden)

    Ehsan Ghasali

    2017-12-01

    Full Text Available This study discusses the potentials of spark plasma sintering (SPS integrated with high temperature process that can enable sintering of SiC/Cf composites without any sintering aids. The random distribution of carbon fibers was obtained through mixing composite components in ethanol by using a shaker mill for 10 min. The corresponding sintering process was carried out at 1900 and 2200 °C with 50 MPa pressure applied at maximum temperature. The results showed that 89 ± 0.9 and 97 ± 0.8% of the theoretical density can be obtained for sintering temperatures of 1900 and 2200 °C, respectively. The densification curves were plotted to monitor sintering behavior with punch displacement changes. The appropriate bonding between SiC particles and carbon fibers was detected using FE-SEM for sample which was sintered at 2200 °C. The clear maximum in hardness (2992 ± 33 Vickers, bending strength (427 ± 26 MPa and fracture toughness (4.2 ± 0.3 MPa m1/2 were identified for sample sintered at 2200 °C. XRD investigations supposed that SiC and carbon were the only crystalline phases in both sintered samples.

  11. Two-step flash light sintering process for crack-free inkjet-printed Ag films

    International Nuclear Information System (INIS)

    Park, Sung-Hyeon; Kim, Hak-Sung; Jang, Shin; Lee, Dong-Jun; Oh, Jehoon

    2013-01-01

    In this paper, a two-step flash light sintering process for inkjet-printed Ag films is investigated with the aim of improving the quality of sintered Ag films. The flash light sintering process is divided into two steps: a preheating step and a main sintering step. The preheating step is used to remove the organic binder without abrupt vaporization. The main sintering step is used to complete the necking connections among the silver nanoparticles and achieve high electrical conductivity. The process minimizes the damage on the polymer substrate and the interface between the sintered Ag film and polymer substrate. The electrical conductivity is calculated by measuring the resistance and cross-sectional area with an LCR meter and 3D optical profiler, respectively. It is found that the resistivity of the optimal flash light-sintered Ag films (36.32 nΩ m), which is 228.86% of that of bulk silver, is lower than that of thermally sintered ones (40.84 nΩ m). Additionally, the polyimide film used as the substrate is preserved with the inkjet-printed pattern shape during the flash light sintering process without delamination or defects. (paper)

  12. Influence of Various Process Parameters on the Density of Sintered Aluminium Alloys

    Directory of Open Access Journals (Sweden)

    Mateusz Laska

    2012-01-01

    Full Text Available This paper presents the results of density measurements carried out on Alumix sintered parts. ECKA Alumix aluminium powders were used because of their wide application in the powder metallurgy industry. The compacts were produced using a wide range of compaction pressures for three different chemical compositions. The compacts were then sintered under a pure dry nitrogen atmosphere at three different temperatures. The heating and cooling rates were the same throughout the entire test. The results showed that the green density increases with compaction pressure, but that sintered density is independent of green density (compaction pressure for each sintering temperature.

  13. Preparation of Ti3Al intermetallic compound by spark plasma sintering

    Science.gov (United States)

    Ito, Tsutomu; Fukui, Takahiro

    2018-04-01

    Sintered compacts of single phase Ti3Al intermetallic compound, which have excellent potential as refractory materials, were prepared by spark plasma sintering (SPS). A raw powder of Ti3Al intermetallic compound with an average powder diameter of 176 ± 56 μm was used in this study; this large powder diameter is disadvantageous for sintering because of the small surface area. The samples were prepared at sintering temperatures (Ts) of 1088, 1203, and 1323 K, sintering stresses (σs) of 16, 32, and 48 MPa, and a sintering time (ts) of 10 min. The calculated relative densities based on the apparent density of Ti3Al provided by the supplier were approximately 100% under all sintering conditions. From the experimental results, it was evident that SPS is an effective technique for dense sintering of Ti3Al intermetallic compounds in a short time interval. In this report, the sintering characteristics of Ti3Al intermetallic compacts are briefly discussed and compared with those of pure titanium compacts.

  14. Process parameter influence on Electro-sinter-forging (ESF) of titanium discs

    DEFF Research Database (Denmark)

    Cannella, Emanuele; Nielsen, Chris Valentin; Bay, Niels

    Electro-sinter-forging (ESF) is a sintering process based on the resistance heating principle, which makes it faster than conventional sintering. The process is investigated as a function of the main process parameters, namely compacting pressure, electrical current density and sintering time....... The present work is focused on analysing the influence of these process parameters on the final density of a disc sample made from commercially pure titanium powder. Applying the design of experiments (DoE) approach, the electrical current was seen to be of largest influence. The maximum obtained density...

  15. Cermet sintering on the oase of molybdenum, nickel, aluminium oxide in dry and wet hydrogen medium

    International Nuclear Information System (INIS)

    Fedotov, A.V.; Lutskaya, E.Eh.

    1985-01-01

    Cermet sintering on the base of molybdenum, nickel and aluminium oxide in dry and wer hydrogen medium is studied. It is stated that presence of water vapours permits to decrease sintering temperature of molybdenum containing cermets and to prepare dense nickeliferous cermets. Cermet density can he rather high at final stages of sintering that is probably conditioned by decrease of growth rate of corundum crystals. Pressing pressure activates cermet siptering at intermediate stages and it is low effective at finite stages of condensation. Constancy of relative reduction of void volume is preserved only at final stages of sintering

  16. Effect of Ca-Fe oxides additives on NOx reduction in iron ore sintering

    Institute of Scientific and Technical Information of China (English)

    Zhi-yuan Yu; Xiao-hui Fan; Min Gan; Xu-ling Chen

    2017-01-01

    As the emission control regulations get stricter, the NOx reduction in the sintering process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain. The NOx emissions from the sintering machine account for 48% of total amount from the iron and steel industry.Thus, it is essential to reduce NOx emissions from the sintering machine, for the achievement of clean production of sinter.Ca-Fe oxides, serving as the main binding phase in the sinter, are therefore used as additives into the sintering mixture to reduce NOx emissions.The results show that the NOx re-duction ratio achieves 27.76% with 8% Ca-Fe oxides additives since the Ca-Fe oxides can advance the ig-nition and inhibit the nitrogen oxidation compared with the conventional condition.Meanwhile, the exist-ence of Ca-Fe oxides was beneficial to the sinter quality since they were typical low melting point com-pounds.The optimal mass fraction of Ca-Fe oxides additives should be less than 8% since the permeability of sintering bed was significantly decreased with a further increase of the Ca-Fe oxides fines, inhibiting the mineralization reaction of sintering mixture.Additionally, the appropriate particle size can be obtained when mixing an equal amount of Ca-Fe oxides additives of -0.5 mm and 0.5-3.0 mm in size.

  17. Real-time operation guide system for sintering process with artificial intelligence

    Institute of Scientific and Technical Information of China (English)

    FAN Xiao-hui; CHEN Xu-ling; JIANG Tao; LI Tao

    2005-01-01

    In order to optimize the sintering process, a real-time operation guide system with artificial intelligence was developed, mainly including the data acquisition online subsystem, the sinter chemical composition controller, the sintering process state controller, and the abnormal conditions diagnosis subsystem. Knowledge base of the sintering process controlling was constructed, and inference engine of the system was established. Sinter chemical compositions were controlled by the strategies of self-adaptive prediction, internal optimization and center on basicity. And the state of sintering was stabilized centering on permeability. In order to meet the needs of process change and make the system clear, the system has learning ability and explanation function. The software of the system was developed in Visual C++ programming language. The application of the system shows that the hitting accuracy of sinter compositions and burning through point prediction are more than 85%; the first-grade rate of sinter chemical composition, stability rate of burning through point and stability rate of sintering process are increased by 3%, 9% and 4%, respectively.

  18. Influence of Coke Ratio on the Sintering Behavior of High-Chromium Vanadium-Titanium Magnetite

    Directory of Open Access Journals (Sweden)

    Songtao Yang

    2017-06-01

    Full Text Available High-chromium vanadium and titanium magnetite (HCVTM sinter has poor properties. The coke ratio has an important effect on the behavior of HCVTM sintering as it affects the mineral phases in the high-chromium vanadium and titanium sinter (HCVTS via changing the sintering temperature and atmosphere. In this work, the sintering behavior of HCVTM mixed with varying coke ratios was investigated through sintering pot tests, X-ray diffraction (XRD, gas chromatographic analysis, and mineral phase analysis. The results show that, with the increase of the coke ratio from 4.0% to 6.0%, leading to the increase of the combustion ratio of the flue gas, the vertical sintering rate and sinter productivity decrease. Meanwhile, with the change of the coke ratio, the content of magnetite, silicate, and perovskite increase, while the hematite and calcium ferrite decrease. In addition, the tumble strength and reduction ability of HCVTS decrease, and its degradation strength increase. It was found that the appropriate coke ratio for the sintering process was 5.0 wt %.

  19. Ceramic thick film humidity sensor based on MgTiO3 + LiF

    International Nuclear Information System (INIS)

    Kassas, Ahmad; Bernard, Jérôme; Lelièvre, Céline; Besq, Anthony; Guhel, Yannick; Houivet, David; Boudart, Bertrand; Lakiss, Hassan; Hamieh, Tayssir

    2013-01-01

    Graphical abstract: - Highlights: • The fabricated sensor based on MgTiO 3 + LiF materials used the spin coating technology. • The response time is 70 s to detect variation between 5 and 95% relative humidity. • The addition of Scleroglucan controls the viscosity and decreases the roughness of thick film surface. • This humidity sensor is a promising, low-cost, high-quality, reliable ceramic films, that is highly sensitive to humidity. - Abstract: The feasibility of humidity sensor, consisting of a thick layer of MgTiO 3 /LiF materials on alumina substrate, was studied. The thermal analysis TGA-DTGA and dilatometric analysis worked out to confirm the sintering temperature. An experimental plan was applied to describe the effects of different parameters in the development of the thick film sensor. Structural and microstructural characterizations of the developed thick film were made. Rheological study with different amounts of a thickener (scleroglucan “sclg”), showing the behavior variation, as a function of sclg weight % was illustrated and rapprochement with the results of thickness variation as a function of angular velocity applied in the spin coater. The electrical and dielectric measurements confirmed the sensitivity of the elaborated thick film against moisture, along with low response time

  20. Ceramic thick film humidity sensor based on MgTiO{sub 3} + LiF

    Energy Technology Data Exchange (ETDEWEB)

    Kassas, Ahmad, E-mail: a.kassas.mcema@ul.edu.lb [Faculty of Agricultural Engineering and Veterinary Medicine, Laboratory of Materials, Catalysis, Environment and Analytical Methods (MCEMA), Faculty of Sciences and Doctoral School of Sciences and Technology (EDST), Lebanese University, Hariri Campus, Hadath, Beirut (Lebanon); Laboratoire Universitaire des Sciences Appliquées de Cherbourg (LUSAC), 50130 Cherbourg-Octeville (France); Bernard, Jérôme; Lelièvre, Céline; Besq, Anthony; Guhel, Yannick; Houivet, David; Boudart, Bertrand [Laboratoire Universitaire des Sciences Appliquées de Cherbourg (LUSAC), 50130 Cherbourg-Octeville (France); Lakiss, Hassan [Faculty of Agricultural Engineering and Veterinary Medicine, Laboratory of Materials, Catalysis, Environment and Analytical Methods (MCEMA), Faculty of Sciences and Doctoral School of Sciences and Technology (EDST), Lebanese University, Hariri Campus, Hadath, Beirut (Lebanon); Faculty of Engineering, Section III, Hariri Campus, Hadath, Beirut (Lebanon); Hamieh, Tayssir [Faculty of Agricultural Engineering and Veterinary Medicine, Laboratory of Materials, Catalysis, Environment and Analytical Methods (MCEMA), Faculty of Sciences and Doctoral School of Sciences and Technology (EDST), Lebanese University, Hariri Campus, Hadath, Beirut (Lebanon)

    2013-10-15

    Graphical abstract: - Highlights: • The fabricated sensor based on MgTiO{sub 3} + LiF materials used the spin coating technology. • The response time is 70 s to detect variation between 5 and 95% relative humidity. • The addition of Scleroglucan controls the viscosity and decreases the roughness of thick film surface. • This humidity sensor is a promising, low-cost, high-quality, reliable ceramic films, that is highly sensitive to humidity. - Abstract: The feasibility of humidity sensor, consisting of a thick layer of MgTiO{sub 3}/LiF materials on alumina substrate, was studied. The thermal analysis TGA-DTGA and dilatometric analysis worked out to confirm the sintering temperature. An experimental plan was applied to describe the effects of different parameters in the development of the thick film sensor. Structural and microstructural characterizations of the developed thick film were made. Rheological study with different amounts of a thickener (scleroglucan “sclg”), showing the behavior variation, as a function of sclg weight % was illustrated and rapprochement with the results of thickness variation as a function of angular velocity applied in the spin coater. The electrical and dielectric measurements confirmed the sensitivity of the elaborated thick film against moisture, along with low response time.