结合系统对刚玉质浇注料显微结构及性能的影响

以板状刚玉骨料和细粉为主要原料，分别以硅微粉、Al2O3-SiO2凝胶粉和铝酸钙水泥为结合剂，制备了3组不同结合系统的刚玉质浇注料，研究了浇注料经不同温度热处理后的物相变化及物理性能，采用X射线衍射及扫描电镜技术研究了其相组成和显微结构特征。结果表明，以硅微粉为结合剂的浇注料在1100℃时有莫来石晶核析出；继续升温，莫来石长大并出现液相。以凝胶粉为结合剂的浇注料在1100℃时出现方石英，不利于莫来石的生成。以铝酸钙水泥为结合剂的浇注料经1500℃处理后，水泥矿物转化为六铝酸钙（CaO·6Al2O3，CA6）相，这种呈片状的CA6相在基质结构内部交叉穿插，有利于提高浇注料的高温抗折强度和抗热震性能。

Influence of bonding system on microstructure and properties of corundum-based castables

Three different corundum-based castables were prepared with tabular alumina aggregates and fines as main raw materials and proper microsilica, Al2 O3-SlO2 gel powder and calcium aluminate cement （CAC） as binders, respectively. The phase evolution and typical physical properties of the castables after different heating treatments were investigated. The microstructures of the castables were analyzed by means of X-ray diffraction （XRD） and scan electron micrograph （SEM）. The results show that the mullite can precipitate in the castable with microsilica bonding at 1 100 ℃. With temperature rising, both the grain growth of muUite and liquid phase formation are confirmed. The mineral of cristobalite is formed in the castable with binder of gel powder at 1 100 ~C, which is unfavorable for the process of mullitzation. At 1500℃, the minerals of calcium aluminate cement in the castable are converted to plate-like calcium hexaluminate （CA6）, the microstructure of crosslinked network formed by CA6 contributes to superior hot modulus of rupture and thermal shock resistance to castable samples.