莫来石结合碳化硅高温吸热陶瓷抗氧化性能的研究

以碳化硅及合成莫来石微粉为主要原料,制备了用于非真空太阳能吸热管的莫来石结合碳化硅高温陶瓷涂层。针对碳化硅基材料高温氧化问题,测定了样品的烧成增重率及亮度并结合XRD、SEM研究了莫来石结合碳化硅陶瓷的抗氧化性能。结果表明,莫来石添加量为20%,经1 380℃烧成样品的抗氧化性最好,其增重率为7.49%,亮度值为46.61。XRD分析烧结体主晶相为碳化硅(α-SiC)和莫来石(3Al2O3.2SiO2),并含有少量的方石英(SiO2),莫来石作为结合相在碳化硅晶粒周围形成"骨架",与SiO2玻璃相形成三围的网状保护层包裹在碳化硅表面,阻止碳化硅氧化。

THE RESEARCH ON OXIDATION RESISITANCE OF MULLITE BONDED SiC HIGH TEMERATURE HEAT ABSORBING CERAMICS

Mullite bonded SiC ceramics as high temperature coating used on the non-vacuum solar receiver tube were prepared from synthetic mullite and silicon carbide powder.The oxidation resistance of mullite bonded SiC ceramics was discussed with reference to the oxidation of carbonized silicon-based material at high temperature and their samples were studied by the X-ray diffraction analysis（XRD）,the scanning electron microscope（SEM） and the testing of luminosity and weight gain.The oxidation resistance of the sample with 20 % of mullite fired at 1380 ℃,of which the oxidation weight gain and luminosity are 7.49 % and 46.61 respectively,is the best.The main crystalline phases determined by XRD were α-SiC,mullite（3Al2O3.2SiO2）,and a small amount of cristobalite（SiO2）.The results showed that SiC was coated by an oxidation preventing three-dimensional network structure formed with mullite as the framework under the role of SiO2.