摘要
自制了SiO2结合SiC砖,然后参照ASTM C863—2000对其在1000℃水蒸气(水蒸气的通入速率为32 kg·m-3·h-1)中分别保温50、100、150、200、250和300 h进行了氧化试验,检测试样氧化后的质量变化率和体积变化率,以及试样氧化前后的显气孔率和孔径分布,并进行了XRD和SEM分析。结果表明:1、自制SiO2结合SiC砖的体积密度、显气孔率和SiC含量与现有的SiC浇注料相当,而抗折强度和耐压强度明显比SiC浇注料的高。2、氧化100 h后试样表面开始出现裂纹;氧化200 h后裂纹增多,变宽。3、随着氧化时间延长至200 h,试样的体积变化率逐渐增大;但氧化250和300 h后又逐渐减小,此乃烧结收缩超过氧化膨胀所致。4、随着氧化时间延长至250 h,试样的质量变化率逐渐增大;但氧化300 h后又减小,可能和氧化后期部分SiO2又转化为SiO气体导致质量损失有关。5、试样显气孔率随氧化时间的变化与质量变化率的变化趋势相反。6、随着氧化时间的延长,氧化后试样中晶相SiO2增多;晶相SiO2与SiC的热膨胀系数失配以及晶相SiO2之间的相变会导致SiC表面的SiO2氧化膜破裂和脱落。提高SiO2结合SiC材料抗水蒸气氧化性的关键在于使SiO2更多地进入玻璃相中。
SiO 2-bonded SiC bricks were prepared and then the steam oxidation test was carried out at 1000℃for 50,100,150,200,250 and 300 h,respectively,with the steam flux of 32 kg·m-3·h-1 according to ASTM C863—2000.The mass change rate and the volume change rate of the specimens after steam oxidation,the apparent porosity and the pore size distribution of the specimens before and after oxidation were tested.The XRD and SEM analyses were also carried out.The results show that:the bulk density,the apparent porosity and the SiC content of the bricks are similar with those of the existing SiC castables,but the CMOR and CCS are obviously higher;cracks begin to appear on the surface of the specimens after 100 h oxidation,then increase and widen after 200 h oxidation;as the oxidation time prolongs to 200 h,the volume change rate becomes higher,but decreases gradually after 250 h and 300 h,which is caused by the sintering shrinkage exceeding the oxidation expansion;as the oxidation time prolongs to 250 h,the mass change rate increases gradually,but decreases after 300 h oxidation,which may be related to the mass loss caused by the transformation from SiO 2 to SiO gas;the trends of the apparent porosity and mass change rate with oxidation time are opposite;with the prolonging oxidation time,the amount of crystalline SiO 2 increases;the SiO 2 film on the SiC surface then ruptures and peels off due to the mismatch of the thermal expansion coefficient between the crystalline SiO 2 and SiC as well as the SiO 2 phase transformation;therefore,the key to improving the steam oxidation resistance of SiO 2-bonded SiC materials is to make more SiO 2 fuse into glass phase.
作者
曹会彦
王建波
黄志刚
李杰
张新华
Cao Huiyan;Wang Jianbo;Huang Zhigang;Li Jie;Zhang Xinhua
出处
《耐火材料》
CAS
北大核心
2020年第1期70-73,共4页
Refractories
基金
洛阳市重大科技专项(No.1901001A)
关键词
SIC材料
SiO2结合SiC砖
水蒸气
氧化
物相组成
显微结构
silicon carbide materials
silica-bonded silicon carbide bricks
steam
oxidation
phase composition
microstructure
作者简介
曹会彦:女,1982年生,硕士,高级工程师。E-mail:caohuiyan318@126.com。
