碳化硅浇注料抗高温水蒸气氧化性能研究

Steam oxidation resistance of silicon carbide castables at elevated temperatures

以电熔白刚玉颗粒、碳化硅颗粒和细粉、活性氧化铝微粉、二氧化硅微粉、纯铝酸钙水泥等为主要原料,制备了SiC含量(w)分别为86%和71%的两种碳化硅浇注料,在1000℃保温3 h热处理后,在1000℃水蒸气中分别进行100、200、300、400和500 h的氧化试验,检测了试样氧化前后的质量变化率、体积变化率、体积密度、显气孔率、常温耐压强度,并进行XRD和SEM分析。结果表明:1)在0~300 h氧化阶段,碳化硅的氧化速率呈增大趋势;在300~500 h氧化阶段,碳化硅的氧化速率很小。2)SiC含量为71%(w)的试样的氧化速率比SiC含量为86%(w)的试样的略大。3)随着试样中碳化硅氧化程度的增大,氧化后试样的显气孔率呈增大趋势,体积密度和常温耐压强度呈减小趋势。

Silicon carbide castables of different SiC contents(86%and 71%,by mass)were prepared using fused white corundum,silicon carbide particles and fines,activated alumina powder,silica powder and pure calcium aluminate cement as main starting materials,heat treating at 1000℃for 3 h,oxidizing in steam atmosphere at 1000℃for different durations(100,200,300,400 and 500 h).The mass and volume before and after oxidation,the bulk density,the apparent porosity and the cold compressive strength were tested.The phase composition and the microstructure before and after oxidation were analyzed by XRD and SEM.The results indicate that:(1)within 300 h of oxidation duration,silicon carbide shows an increasing oxidation rate;however,the oxidation rate is low during 300-500 h of oxidation duration;2)the oxidation rate of the specimen with 71%SiC is slightly higher than the one with 86%SiC;3)with the increasing oxidation degree of silicon carbide,the apparent porosity of the specimens tends to increase,followed by the declining bulk density and cold compressive strength.