Junbao ZHANG
,
Guangwu WEN
,
Tingquan LEI
,
Dechang JIA
,
Jiancun RAO
材料科学技术（英文）
Si-B-O-N powder without B-O bonds synthesized by polymeric precursor were hot-pressed into ceramics at different temperatures. The variations of microstructure and mechanical properties of Si-B-O-N ceramics have been investigated. Crystallization of Si-B-O-N ceramics occurred at about 1400°C. Density, elastic modulus, and flexural strength of the ceramics increased with the increasing sintering temperatures, and reached to their maximum values at 1600°C. By contrast,hardness and fracture toughness of the ceramics monotonically changed with increasing sintering temperatures. Hardness decreased, while the fracture toughness increased. The principal toughening mechanisms including crack deflection, crack bridging and plate grain pulling-out effects are discussed
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Si-B-O-N ceramics
,
null
,
null
,
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Junbao ZHANG
,
Tingquan LEI
,
Guangwu WEN
,
Yu ZHOU
材料科学技术（英文）
Amorphous silicon oxynitride powders have been obtained by pyrolysis of polysiloxazane in a stream of anhydrous NH3 at the temperature up to 1000℃. The polysiloxazane is fabricated from ammonolysis of chloropolysiloxane that is produced by the hydrolysis of silicon tetrachloride. The conversion of polysiloxazane to silicon oxynitride and the structural features of the final powders have also been studied by infrared spectra, elemental composition and X-ray diffraction analysis and SEM observation.
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