To improve the corrosion resistance of porous Si3N4 used in the high temperature environments, which contain water vapor and volatile species, porous Si3N4-Lu2Si2O7 composite ceramics were fabricated by a process of oxidation bonding and pressureiess sintering in flowing N2 atmosphere at the temperatures lower than 1550℃. The pores in ceramics were formed by removing the pore-forming agent (phenolic resin). SiO2 derived by the oxidation of Si3N4 at 1250℃ in air reacted with Lu2O3 at various sintering temperatures, leading to the formation of Lu2Si207 with excellent oxidation and corrosion resistance. The phase composition, microstructure, and mechanical properties of the porous ceramics depended on the sintering temperatures. Si3N4-Lu2Si2C7 composite ceramics with the porosity of 52% and the pore size of 0.2 μm were obtained by oxidation bonding at 1250℃ for 1 h and pressureiess sintering at 1550℃ for 2 h using 4 wt pet Lu2O3 additive.
参考文献
| [1] | T. Kingetsu;M. Takehara;T. Yarii;K. Ito;H. Masumoto .Correlation between the oxidation behavior and the microstructure of SiC coatings deposited on graphite substrates via chemical vapor deposition[J].Thin Solid Films: An International Journal on the Science and Technology of Thin and Thick Films,1998(1/2):139-143. |
| [2] | Naoto Hirosaki;Yoshinobu Yamamoto;Toshiyuki Nishimura .Phase Relationships in the Si_3N_4-SiO_2-Lu_2O_3 System[J].Journal of the American Ceramic Society,2002(11):2861-2863. |
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