Tribological Characteristics Manufactures SiC by Liquid Phase Sintered Method

2006 ◽  
Vol 324-325 ◽  
pp. 1177-1180
Author(s):  
Won Jo Park ◽  
Sun Chul Huh ◽  
Sung Ho Park ◽  
Hong Tae Song
Keyword(s):  
Wear Resistance ◽  
Liquid Phase ◽  
Coefficient Of Thermal Expansion ◽  
Average Particle Size ◽  
High Temperature Strength ◽  
Average Particle ◽  
Pressing Method ◽  
Sintering Additives ◽  
Resistance To Oxidation ◽  
Sic Composites

SiC materials have excellent high temperature strength, low coefficient of thermal expansion, good resistance to oxidation and good thermal and chemical stability etc. In this study, monolithic liquid phase sintered SiC (LPS-SiC) was made by hot pressing method with nano-SiC powder an average particle size is 30nm and less. Alumina (Al2O3), yttria (Y2O3) and silica (SiO2) particles were used for sintering additives. To investigate effects of SiO2, Al2O3/Y2O3 composition was fixed and then ratios of SiO2 were changed as seven kinds. Materials have been sintered for 1 hour at 1760, 1780 and 1800 under the pressure of 20MPa. The system of sintering additives which affects a property of sintering as well as the influence depending on compositions of sintering additives were investigated by measurement of density, mechanical properties such as Vickers hardness and sliding wear resistance were investigated to make sure of the optimum condition which is about matrix of SiCf/SiC composites. The abrasion test condition applies to load of 20N at 100rpm for 20min. Sintered density, abrasion property of fabricated LPS-SiC increased with increasing the sintering temperature. In case of LPS-SiC with low SiO2 content, has very excellent wear resistance.

Fracture Toughness of Liquid Phase Sintered SiC by Using Indentation Fracture Method

2005 ◽  
Vol 297-300 ◽  
pp. 137-142
Author(s):  
Hun Chae Jung ◽  
Han Ki Yoon ◽  
Bu Ahn Kim ◽  
Joon Soo Park ◽  
Akira Kohyama
Keyword(s):  
Fracture Toughness ◽  
Liquid Phase ◽  
Coefficient Of Thermal Expansion ◽  
Average Particle Size ◽  
Chemical Vapor Deposition Method ◽  
High Temperature Strength ◽  
Average Particle ◽  
Indentation Fracture ◽  
Pressing Method ◽  
Sintering Additives

SiC materials have excellent high temperature strength, low coefficient of thermal expansion, good resistance to oxidation and good thermal and chemical stability etc. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture still impose a severe limitation on practical applications of SiC materials. Therefore, in the interests of safety, we are required to measure fracture toughness of materials. In the present work, monolithic Liquid Phase Sintered SiC (LPS-SiC) was fabricated by hot pressing method under 20MPa using sintering additives at different temperature such as 1760oC, 1780oC, 1800oC and 1820oC. The starting powder was high purity β-SiC nano-powder with an average particle size of 30nm. Compositions of sintering additives were Al2O3 / Y2O3 = 0.7 and 1.5 (wt. %). Monolithic LPS-SiC was evaluated in terms of sintering density, hardness and fracture toughness through indentation fracture method by the Vickers hardness tester. Sintered density, hardness and fracture toughness of fabricated LPS-SiC increased with the increase of sintering temperature. They are higher than those of fabricated SiC by the chemical vapor deposition method.

Effect of Sintering Additives on Fabrication Properties of Liquid Phase Sintered SiC

2005 ◽  
Vol 297-300 ◽  
pp. 2539-2544 ◽  
Author(s):  
Han Ki Yoon ◽  
Yi Hyun Park ◽  
Joon Soo Park ◽  
Akira Kohyama
Keyword(s):  
Fracture Toughness ◽  
High Temperature ◽  
Liquid Phase ◽  
Hot Pressing ◽  
Bending Test ◽  
Average Particle ◽  
Pressing Method ◽  
Sintering Additives ◽  
Temperature And Pressure ◽  
Sic Composites

SiC has been extensively studied for high temperature components in advanced energy system and gas turbine because of its excellent high temperature mechanical properties and good thermal-chemical stability etc. However, the brittle characteristics of SiC such as low fracture toughness and low strain-to fracture still impose a severe limitation on practical applications of SiC materials. For these reasons, SiCf/SiC composites can be considered as a promising for various structural materials, because of their good fracture toughness compared with monolithic SiC. But, high temperature and pressure lead to the degradation of the reinforcing fiber during the hot pressing. Therefore, reduction of sintering temperature and pressure is key requirements for the fabrication of SiCf/SiC composites by hot pressing method. In the present work, monolithic Liquid Phase Sintered SiC (LPS-SiC) was fabricated by hot pressing method in Ar atmosphere at 1800oC under 20MPa using Al2O3, Y2O3 and SiO2 as sintering additives. The starting powder was high purity β-SiC nano-powder with an average particle size of 30nm. The characterization of LPS-SiC was investigated by means of SEM and three point bending test. Base on the composition of sintering additives-, microstructure- and mechanical property correlation, the compositions of sintering additives are discussed.

Fabrication and Strength Properties of LPS-SiC Ceramics

2005 ◽  
Vol 287 ◽  
pp. 183-188 ◽  
Author(s):  
Yi Hyun Park ◽  
Dong Hyun Kim ◽  
Han Ki Yoon ◽  
Akira Kohyama
Keyword(s):  
Elastic Modulus ◽  
High Temperature ◽  
Flexural Strength ◽  
Hot Pressing ◽  
Average Particle Size ◽  
Process Temperature ◽  
Average Particle ◽  
Pressing Method ◽  
Temperature And Pressure ◽  
Sic Composites

SiC materials have been extensively studied for high temperature components in advanced energy system and advanced gas turbine. SiCf/SiC composites are promising for various structural materials. But, high temperature and pressure lead to the degradation of the reinforcing fiber during the hot pressing. Therefore, reduction of the process temperature and pressure is key requirements for the fabrication of SiCf/SiC composites by hot pressing method. In the present work, monolithic LPS-SiC was fabricated by hot pressing method at various temperatures. The starting powder was high purity β-SiC nano-powder with an average particle size of 30nm. Compositions of sintering additives were Al2O3 / Y2O3 = 0.7 and 1.5 (wt.%). Monolithic LPS-SiC was evaluated in terms of sintering density, micro-structure, flexural strength, elastic modulus and so on. Sintered density, flexural strength and elastic modulus of fabricated LPS-SiC increased with increasing the process temperature. Particularly, relative density of LPS-SiC fabricated at 1820oC with additive composition of Al2O3/Y2O3=1.5(wt.%) was 95%. Also, flexural strength and elastic modulus were 900MPa and 220GPa, respectively. In the fracture surface of this specimen, the size and shape of SiC grains grew up and changed. Also, tortuous crack paths and occurrence of interfacial debonding were observed.

CHARACTERIZATION OF LIQUID PHASE SITERED SIC AND SIC/SIC COMPOSITE MATERIALS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 2916-2921 ◽  
Author(s):  
MOON HEE LEE ◽  
SANG PILL LEE ◽  
KWAN DO HUR
Keyword(s):  
Liquid Phase ◽  
Flexural Strength ◽  
Fracture Behavior ◽  
Sintered Density ◽  
Secondary Phase ◽  
Sintering Additives ◽  
Catastrophic Fracture ◽  
Sic Composites ◽  
Composition Ratios

The characterization of liquid phase sintered(LPS) SiC based materials has been investigated with the analysis of microstructure and flexural strength. Especially, LPS - SiC materials were examined for the variation of test temperature and composition ratios ( Al 2 O 3,/ Y 2 O 3) of sintering additives. LPS - SiC based materials were fabricated by hot pressing(HP) associated with the liquid phase formation of sintering additives( Al 2 O 3, Y 2 O 3). LPS - SiCf / SiC composites were also fabricated with plane-woven(PW) Tyranno-SA fibers without an interfacial layer. LPS - SiC materials showed a dense morphology with the creation of the secondary phase like YAG. The composition ratio of sintering additives led to the variation of sintered density and flexural strength. The flexural strength of LPS - SiC materials was greatly decreased at the temperature higher than 1000°C. LPS - SiCf / SiC composites represented an average flexural strength of about 260 MPa, accompanying the catastrophic fracture behavior without any full-out phenomena.

scholarly journals Effect of ZrB2 Particle Size on Pressureless Sintering of ZrB2 - ß-Sic Composites

2019 ◽  
Author(s):  
Rosa Maria da Rocha ◽  
Frank Ferrer Sene ◽  
Mariah de Oliveira Juliani ◽  
Caroline Oliveira Davi
Keyword(s):  
Particle Size ◽  
Flexural Strength ◽  
Average Particle Size ◽  
Theoretical Density ◽  
Average Particle ◽  
Pressureless Sintering ◽  
High Melting Temperature ◽  
Powder Samples ◽  
Effect Of Particle Size ◽  
Sic Composites

Zirconium diboride is an ultra high temperature ceramic material that leads this emerging class of materials because of its distinct combination of properties, including high melting temperature (> 3000 °C) and the lowest theoretical density (6.09 g·cm-3) among the borides. This combination of properties makes ZrB2 candidate for airframe leading edges on sharp-bodied reentry vehicles. In this work, the effect of particle size of ZrB2 on the pressureless sintering of ZrB2-SiC composites was studied, using ZrB2 powder with average particle size of 2.6 and 14.2µm. Four different vol% concentration of ß-SiC (0, 10, 20 and 30 vol%) were added to as-received and planetary milled ZrB2 powder. Samples were pressureless sintered at 2050 °C/1h in argon atmosphere. The reduction of initial ZrB2 particle size led to composites with better results of densification, mechanical properties and oxidation resistance regardless ß-SiC addition, showing relative densities around 92.5 %Theoretical Density (Td) and flexural strength and microhardness around 260 MPa and 17.5 GPa, respectively. Composites processed with as-received ZrB2 powder showed increasing in densification and flexural strength with the SiC content increasing. Relative density varied from 74.7 to 90.8 %TD and flexural strength from 102 to 241 MPa, for 0 and 30 vol% of SiC, respectively.

Mechanical Properties and Fabrication of Silicon Carbide Ceramic by NITE Method

2007 ◽  
Vol 124-126 ◽  
pp. 699-702
Author(s):  
Han Ki Yoon ◽  
Young Ju Lee ◽  
Yi Hyun Park ◽  
Joon Soo Park ◽  
Akira Kohyama
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Average Particle Size ◽  
Bending Test ◽  
Average Particle ◽  
Pressing Method ◽  
Three Point Bending ◽  
Nano Powder ◽  
Strength Characterization ◽  
Sintered Temperature

Nano infiltration transient eutectic ceramic (NITE-SiC) was fabricated by hot pressing method using Al2O3 and Y2O3 as sintering additives. The ratio of the Al2O3/Y2O3 additives was changed between 6:4 and 4:6. The densification and mechanical properties were investigated for the sintered temperature. The starting powder was high purity β -SiC nano-powder with an average particle size of 30nm. The bending strength characterization and densification of NITE-SiC was investigated by the FE-SEM and three point bending test.

scholarly journals Application of Silica–Coated Magnetite on a Steel Plate and its Frictional and Thermal Effect

2020 ◽  
Vol 65 (1) ◽  
pp. 76-85
Author(s):  
Indri Dayana ◽  
Anggito P. Tetuko ◽  
Timbangen Sembiring ◽  
Kurnia Sembiring ◽  
Nining S. Asri ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Steel Plate ◽  
Average Particle Size ◽  
Optical Microscope ◽  
Average Particle ◽  
Friction Process ◽  
Magnetite Fe3o4 ◽  
Promising Application ◽  
Magnetite Particles ◽  
Dsc Curves

The magnetite (Fe3O4) particles that have been coated using tetraethyl orthosilicate (TEOS) as silica precursors were used as the additive in the lubricant. The effects of silica-coated magnetite additive on the thermal properties of ferro-lubricant and reducing the friction on a steel plate have been investigated. The characterizations were conducted at both conditions: with and without the addition of Fe3O4 particles. The characterization using TEM proposed that the average particle size of the silica-coated magnetite particles is 150 nm. The TGA/DSC curves of the silica-coated magnetite particles suggested a gradual weight loss obtained as the temperature increased. The endothermic peak was obtained at ~37 and 50 °C. The silica-coated magnetite particles’ additive increases both the density and viscosity of 0.84 g/cm3 and 134.29 cSt. The silica-coated magnetite particles additive in the lubricant enhances the thermal conductivity and specific heat of 0.151 W/m.K and 1600 J/kg.K. Ferro-lubricant reduces the friction coefficient up to 0.02 (static) and 0.005 (dynamic). The wear resistance of the plate could be improved as analyzed using an optical microscope. These results demonstrate a promising application of the silica-coated magnetite particles as an additive in the lubricant. Therefore improving wear resistance and cooling during the friction process.

scholarly journals Passage kinetics of digesta in horses fed with coastcross hay ground to different degrees

2014 ◽  
Vol 38 (5) ◽  
pp. 506-514 ◽  
Author(s):  
Vinicius Pimentel Silva ◽  
Fernando Queiroz de Almeida ◽  
Róbson Ricardo Moreira Pimentel ◽  
Fernanda Nascimento de Godoi ◽  
Tiago Marques dos Santos ◽  
...  
Keyword(s):  
Particle Size ◽  
Liquid Phase ◽  
Transit Time ◽  
Solid Phase ◽  
Average Particle Size ◽  
Neutral Detergent Fiber ◽  
Average Particle ◽  
Passage Rate ◽  
The Right ◽  
Kinetics Of

This study was conducted to evaluate the kinetics, physicochemical characteristics and particle size of digesta in the right ventral colon (RVC) of horses fed coastcross hay ground to different degrees. Four horses fitted with cannulae in the RVC were used and were fed the following forms of hay: long, chopped, ground to 5 mm and ground to 3 mm. A Latin Square 4x4 study design was used. Each experimental period included 10 days for diet adaptation, four days for feces collection and one day for digesta collection. The kinetics of the particulate and solute phases of digesta were evaluated based on the mean retention time (MRT), passage rate (k) and transit time (TT) using two external markers: Cr-NDF and Co-EDTA. The TT of solid phase digesta was 3 hours longer (P<0.05) for ground hay than with the other physical forms of hay. There was no difference (P>0.05) in k or MRT in either the liquid or solid phase of digesta as a function of the different degrees of hay grinding. However, the liquid phase of digesta presented a higher k than the solid phase, with values of 3.28 and 2.73 h-1 being obtained, respectively. The smallest particle size and the lowest neutral detergent fiber contents in colon digesta were observed when hay ground to 3 mm was offered, leading to values of 0.51 mm and 53.46%, respectively. Grinding the hay increased the transit time of the liquid phase in the digestive tract of the horses, whereas no change in the kinetics of the solid phase digesta was observed. The grinding of hay reduced the NDF and the average particle size in the right ventral colon.

VANASIL 77

Alloy Digest ◽  
1973 ◽  
Vol 22 (8) ◽  
Keyword(s):  
Wear Resistance ◽  
High Temperature ◽  
Coefficient Of Thermal Expansion ◽  
High Strength ◽  
Heat Treating ◽  
Corrosion And Wear ◽  
High Temperature Strength ◽  
Light Weight ◽  
Casting Alloy ◽  
Temperature Performance

Abstract VANASIL 77 is an age-hardenable hypereutectic aluminum-silicon casting alloy having a low coefficient of thermal expansion and excellent wear resistance. These factors, combined with excellent high-temperature strength make it an excellent material for applications where light weight is required in combination with excellent wear resistance, dimensional stability, and high strength. Permanent molding is required to control properties. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on high temperature performance, corrosion and wear resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-208. Producer or source: Gould Inc., Clevite Engine Parts Division.

scholarly journals Self-Regulating Electrically Conductive Materials Based on Polyethylene Compositions with UHMWPE and Carbon Black

2019 ◽  
Vol 14 (2) ◽  
pp. 60-69 ◽  
Author(s):  
A. V. Markov ◽  
A. S. Chizhov
Keyword(s):  
Carbon Black ◽  
Heat Resistance ◽  
Elevated Temperatures ◽  
Average Particle Size ◽  
Cross Linking ◽  
Average Particle ◽  
Thermal Coefficient ◽  
Electrically Conductive ◽  
Pressing Method ◽  
Conductive Materials

Electrically conductive composites based on high density polyethylene (HDPE) / ultrahigh molecular weight polyethylene (UHMWPE) blends filled with carbon black were studied. The work is a part of the research of electrically conductive materials for the manufacture of self-regulating polymer heaters. In this work, the authors investigated composites based on HDPE/UHMWPE (molecular mass of ~ 7 million) blends filled with carbon black (average particle size ~ 20 nm). The goal of the work was to obtain a self-regulating electrically conductive polymer material with optimal thermoelectric characteristics and high heat resistance. It was shown that the effect of adding UHMWPE to the HDPE/carbon black composites on the thermoelectric behavior of the resulting material was similar to cross-linking. This reduced the undesirable effect of the negative thermal coefficient (NTC) of the electrical resistance. In addition, the heat resistance of the material at elevated temperatures was increased. This makes it possible to exclude the radiation or chemical cross-linking in the manufacture of self-regulating polymer heating elements. The rheological, mechanical and thermoelectric properties of HDPE/carbon black composites modified with UHMWPE were also studied. It was found that a diffusion interphase layer with a reduced fluidity in the melt of HDPE/UHMWPE blends was formed. It was established that self-regulating composites containing 30–40% of UHMWPE had the best operational properties. We can recommend the methods of extrusion and injection molding for the processing of HDPE/carbon black composites mixed with 30% UHMWPE, and the pressing method in case of UHMWPE content of 40%. The ability of the composites to be molded is sharply reduced at higher contents of UHMWPE.

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