Liquid phase sintered silicon carbide (LPS-SiC) ceramics having remarkably high oxidation resistance in wet air

The influence of microstructural variations on the macro/microhardness, nanohardness and Young`s modulus of liquid phase sintered silicon carbide (LPS SiC) has been observed. In order to modify the microstructures some samples were further heat treated at 1850°C for 5 hours to promote grain growth. The depth-sensing indentation tests of SiC materials were performed at several peak loads in the range 10-400 mN. For a better assessment, the indentation values of hardness and Young`s modulus modulus of SiC matrix were also compared to the hardness and Elastic modulus of individual SiC grains. The comparison of macro/micro and nanohardness showed that nanohardness was significantly higher, generally by 6-7 GPa. The nanohardness of individual plate-like SiC grains was around 2 GPa higher than nanohardness of SiC matrix.

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Effects of rare-earth oxide and alumina additives on thermal conductivity of liquid-phase-sintered silicon carbide

Journal of Materials Research ◽

10.1557/jmr.2003.0259 ◽

2003 ◽

Vol 18 (8) ◽

pp. 1854-1862 ◽

Cited By ~ 41

Author(s):

You Zhou ◽

Kiyoshi Hirao ◽

Yukihiko Yamauchi ◽

Shuzo Kanzaki

Keyword(s):

Thermal Conductivity ◽

Silicon Carbide ◽

Rare Earth ◽

Liquid Phase ◽

Point Defects ◽

Rare Earth Oxide ◽

Low Oxygen ◽

Sic Ceramics ◽

Sintered Silicon ◽

Thermal Conductivities

SiC ceramics were prepared from a β–SiC powder doped with two different sintering additives—a mixture of La2O3and Y2O3and a mixture of Al2O3and Y2O3—by hot pressing and annealing. Their microstructures, phase compositions, lattice oxygen contents, and thermal conductivities were evaluated. The SiC doped with rare-earth oxides attained thermal conductivities in excess of 200 W/(m K); however, the SiC doped with additives containing alumina had thermal conductivities lower than 71 W/(m K). The high thermal conductivity of the rare-earth-oxide-doped SiC was attributed to the low oxygen content in SiC lattice, high SiC–SiC contiguity, and lack of β– to α–SiC polytypic transformation. The low thermal conductivity of the alumina-doped SiC was attributed to the point defects resulting from the dissolution of Al2O3into SiC lattice and the occurrence of polytypic transformation.

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COLMONOY No. 21

Alloy Digest ◽

10.31399/asm.ad.ni0504 ◽

1996 ◽

Vol 45 (3) ◽

Keyword(s):

Cast Iron ◽

Physical Properties ◽

Oxidation Resistance ◽

Base Alloy ◽

Nickel Base Alloy ◽

Powder Metal ◽

High Oxidation ◽

High Oxidation Resistance ◽

Nickel Base

Abstract Colmonoy No. 21 is a nickel-base alloy for repairing cast iron parts. The deposit has high oxidation resistance, develops a hardness of Rockwell C 26-31, and is easily finished by filing or grinding. This datasheet provides information on composition, physical properties, and hardness. It also includes information on machining, joining, and powder metal forms. Filing Code: Ni-504. Producer or source: Wall Colmonoy Corporation.

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