摘要
Al2O3-SiC-C specimens were prepared using white fused corundum （3-1,≤1 and ≤0.044 mm）,Al2O3-SiC composite powders （d50 ≤ 5 μm）,α-Al2O3 micropowder （d50 =1.2 μm）,SiC powder （≤ 0.044 mm）,flake graphite （≤ 0.088 mm）,Si powder （d50 =42.8 μm） and B4C powder （d50 ≤10 μm） as main starting materials,and thermosetting phenolic resin as binder.4%,8%,12% and 16% （in mass,the same hereinafter） of Al2O3-SiC composite powders substituted the same quantity of α-Al2O3 micropowder ＋ SiC powder.Effects of composite powder additions on apparent porosity,bulk density,cold modulus of rupture,cold crushing strength,hot modulus of rupture （1 400 ℃）,thermal shock resistance （1 100 ℃,water quenching） and oxidation resistance （1 000 and 1 500 ℃） of Al2O3-SiC -C specimens after 180 ℃ curing,1 000 ℃ 3 h carbon-embedded firing and 1 500 ℃ 3 h carbon-embedded firing,respectively,were researched.The results indicate that：（1） with the increase of Al2O3-SiC composite powder,cold strengths of the cured specimens decline,those of the specimens fired at 1 000 ℃ change a little,and those of the specimens fired at 1 500 ℃ change a little except for an obvious improvement of cold crushing strength ; （2） with the increase of Al2O3-SiC composite powder,hot modulus of rupture at 1 400 ℃ decreases and thermal shock resistance enhances significantly; （3） when Al2O3-SiC composite powder addition is 4%,the oxidation resistance at 1 500 ℃ is the best,and the reason may be the composite powder is finer and more active,which is beneficial to form dense mullite protective layer to retard the O2 diffusion into the specimens.
Al2O3-SiC-C specimens were prepared using white fused corundum （3-1,≤1 and ≤0.044 mm）,Al2O3-SiC composite powders （d50 ≤ 5 μm）,α-Al2O3 micropowder （d50 =1.2 μm）,SiC powder （≤ 0.044 mm）,flake graphite （≤ 0.088 mm）,Si powder （d50 =42.8 μm） and B4C powder （d50 ≤10 μm） as main starting materials,and thermosetting phenolic resin as binder.4%,8%,12% and 16% （in mass,the same hereinafter） of Al2O3-SiC composite powders substituted the same quantity of α-Al2O3 micropowder ＋ SiC powder.Effects of composite powder additions on apparent porosity,bulk density,cold modulus of rupture,cold crushing strength,hot modulus of rupture （1 400 ℃）,thermal shock resistance （1 100 ℃,water quenching） and oxidation resistance （1 000 and 1 500 ℃） of Al2O3-SiC -C specimens after 180 ℃ curing,1 000 ℃ 3 h carbon-embedded firing and 1 500 ℃ 3 h carbon-embedded firing,respectively,were researched.The results indicate that：（1） with the increase of Al2O3-SiC composite powder,cold strengths of the cured specimens decline,those of the specimens fired at 1 000 ℃ change a little,and those of the specimens fired at 1 500 ℃ change a little except for an obvious improvement of cold crushing strength ; （2） with the increase of Al2O3-SiC composite powder,hot modulus of rupture at 1 400 ℃ decreases and thermal shock resistance enhances significantly; （3） when Al2O3-SiC composite powder addition is 4%,the oxidation resistance at 1 500 ℃ is the best,and the reason may be the composite powder is finer and more active,which is beneficial to form dense mullite protective layer to retard the O2 diffusion into the specimens.
