硅铝凝胶粉结合SiAlON增强A1_2O_3-SiC-C浇注料

Effect of silica-alumina colloid powder on properties of SiAlON-reinforced Al_2O_3-SiC-C castables

以电熔致密刚玉和碳化硅为骨料,硅铝凝胶粉、氮化硅粉、硅粉为细粉,制成SiAlON增强Al2O3-SiC-C浇注料,研究了硅铝凝胶粉的加入量分别为1%、3%、5%(质量分数,下同)时对此浇注料的烧结性能、力学性能的影响。结果表明:采用硅铝凝胶粉取代纯铝酸钙水泥作结合剂,可使SiAlON增强Al2O3-SiC-C浇注料在经中温、高温热处理后的常温抗折强度及耐压强度较大提高,中温、高温强度提高幅度更大。另外,随着硅铝凝胶粉加入量的增加,浇注料的常温及高温强度呈先增大而后减小的趋势。由X射线衍射和扫描电镜分析结果可知,硅铝凝胶粉的加入既有利于降低βSiAlON的生成温度,又可以减少材料中的低熔物质。分布均匀、发育良好的粒状βSiAlON的形成是SiAlON增强Al2O3-SiC-C浇注料较水泥结合浇注料强度高的根本原因。

The SiAlON-reinforced A1_2O_3-SiC-C castables were prepared with fused dense corundum (mass ratio 70%) and SiC (10%) as aggregates,silica-alumina colloid powder(1%~5%),SiC powder(5%~10%) and microsilica (5%~10% )as matrix.The effects of additions of silica-alumina colloid powder (1%,3% and 5% respectively) on sintering and mechanical properties of the Al_2O_3-SiC-C materials were studied.The results show that:(1) Replacing calcium aluminate cement with silica-alumina colloid powder as binder,the cold MOR and crushing strength of the castables after treated at 1000 ℃ for 3 h and 1450 ℃ for 3 h respectively increase apparently,especially the hot MOR(1400 ℃ 0.5 h);(2)The cold and hot strength of the castables initially increase and then begin to decrease with the increase of colloid powder addition;3 Based on the XRD,SEM and TEM analysis,it is concluded that the addition of nano-sized colloid powder as binder is beneficial to decreasing the forming temperature of β-SiAlON and reducing the quantity of low melting-point materials.The pre-formation of β-SiAlON which is evenly distributed and its further growth at higher temperature is proved to be the essential reason that the castables have higher strength than that of cement-bonded ones.