Mullite coating on recrystallized silicon carbide was successfully prepared by the sol-gel route. The cycling oxidation of coated recrystallized silicon carbide was performed at 1500℃. For comparison, the oxidation o...Mullite coating on recrystallized silicon carbide was successfully prepared by the sol-gel route. The cycling oxidation of coated recrystallized silicon carbide was performed at 1500℃. For comparison, the oxidation of uncoated recrystallized silicon carbide was also carried out at the same condition. The results in- dicated that a layer of compact, adhesive and crack free mullite coating was found on the recrystallized silicon carbide. After oxidation, the new coatings exhibit adherence and crack resistance under thermal cycling between room temperature and 1500℃, therefore the oxidation resistance capability of silicon carbide was enhanced. With the increase of the dipping frequencies, namely, the increase of the thickness of mullite coating, the oxidation resistance of silicon carbide would be futher improved. The formation mechanism of mullite coating was analyzed and discussed and the oxidation dynamics model of coatedmullite silicon carbide has been also proposed.展开更多
In this work, the effect of microsilica addition on properties of mullite-corundum ceramic specimens fired at temperatures from 1550℃ to 1700℃ has been investigated, it is found that the temperature at 1650℃ is an ...In this work, the effect of microsilica addition on properties of mullite-corundum ceramic specimens fired at temperatures from 1550℃ to 1700℃ has been investigated, it is found that the temperature at 1650℃ is an important turning point for the sintering of mullite-corundum ceramic. When the firing temperature exceeds 1650℃, the mullite phase will decompose, which affects the properties and microstructure of the ceramic. The bulk density of the ceramic decreases with the microsilica addition, but increases with the firing temperature from 1550℃ up to 1700℃. The cold compressive strength of the specimens increases with firing temperature. Thermal shock resistance of the ceramic is strongly dependent on firing temperature, but little on the chosen microsilica addition.展开更多
文摘Mullite coating on recrystallized silicon carbide was successfully prepared by the sol-gel route. The cycling oxidation of coated recrystallized silicon carbide was performed at 1500℃. For comparison, the oxidation of uncoated recrystallized silicon carbide was also carried out at the same condition. The results in- dicated that a layer of compact, adhesive and crack free mullite coating was found on the recrystallized silicon carbide. After oxidation, the new coatings exhibit adherence and crack resistance under thermal cycling between room temperature and 1500℃, therefore the oxidation resistance capability of silicon carbide was enhanced. With the increase of the dipping frequencies, namely, the increase of the thickness of mullite coating, the oxidation resistance of silicon carbide would be futher improved. The formation mechanism of mullite coating was analyzed and discussed and the oxidation dynamics model of coatedmullite silicon carbide has been also proposed.
文摘In this work, the effect of microsilica addition on properties of mullite-corundum ceramic specimens fired at temperatures from 1550℃ to 1700℃ has been investigated, it is found that the temperature at 1650℃ is an important turning point for the sintering of mullite-corundum ceramic. When the firing temperature exceeds 1650℃, the mullite phase will decompose, which affects the properties and microstructure of the ceramic. The bulk density of the ceramic decreases with the microsilica addition, but increases with the firing temperature from 1550℃ up to 1700℃. The cold compressive strength of the specimens increases with firing temperature. Thermal shock resistance of the ceramic is strongly dependent on firing temperature, but little on the chosen microsilica addition.
