Abstract
To improve the corrosion resistance of porous Si 3 N 4 used in the high temperature environments, which contain water vapor and volatile species, porous Si 3 N 4 -Lu 2 Si 2 O 7 composite ceramics were fabricated by a process of oxidation bonding and pressureless sintering in flowing N 2 atmosphere at the temperatures lower than 1550°C. The pores in ceramics were formed by removing the pore-forming agent (phenolic resin). SiO 2 derived by the oxidation of Si 3 N 4 at 1250°C in air reacted with Lu 2 O 3 at various sintering temperatures, leading to the formation of Lu 2 Si 2 O 7 with excellent oxidation and corrosion resistance. The phase composition, microstructure, and mechanical properties of the porous ceramics depended on the sintering temperatures. Si 3 N 4 -Lu 2 Si 2 O 7 composite ceramics with the porosity of 52% and the pore size of 0.2 μm were obtained by oxidation bonding at 1250°C for 1 h and pressureless sintering at 1550°C for 2 h using 4 wt pct Lu 2 O 3 additive.
Published Version
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