Abstract: In order to improve the insulation performance of MgO materials for electric heating tubes,modified Al₂O₃-SiO₂ composite powders with different mass ratios of Al₂O₃/SiO₂ were prepared by KH-550 organic modifier,and then the modified composite powder and MgO powder were mixed evenly according to the mass ratio of 1∶10 to obtain Al₂O₃-SiO₂-MgO composite powder.The properties of the Al₂O₃-SiO₂ composite powder and the electrical insulation properties of the Al₂O₃-SiO₂-MgO composite powder were studied.The results show that:the surface of organically modified SiO₂ and Al₂O₃ powders is grafted with coupling agent,and the agglomeration between particles is improved;when m(Al₂O₃)∶m(SiO₂)=1∶4,the tap density of the Al₂O₃-SiO₂ composite powder is 0.90 g·cm^-3,the activation index is 40.9%,and the dispersion and fluidity are the best;the leakage current of the Al₂O₃-SiO₂-MgO powder is 0.33 mA,and the electrical insulation performance is the best.

Key words: magnesia material, alumina-silica composite powder, surface modification, electrical insulation performance, dispersibility

摘要： 为改善电热管用MgO材料的绝缘性能,先采用KH-550有机改性剂制得Al₂O₃、SiO₂质量比不同的改性Al₂O₃-SiO₂复合粉体,再将改性的复合粉与MgO粉按1∶10的质量比混合均匀得到Al₂O₃-SiO₂-MgO复合粉体。研究了Al₂O₃-SiO₂复合粉的性能和Al₂O₃-SiO₂-MgO复合粉体的电绝缘性能。结果表明:有机改性后的SiO₂、Al₂O₃粉体表面有偶联剂接枝,颗粒间团聚现象得到改善。当Al₂O₃、SiO₂质量比为1∶4时,Al₂O₃-SiO₂复合粉体的振实密度为0.90 g·cm^-3,活化指数为40.9%,分散性和流动性最优;Al₂O₃-SiO₂-MgO复合粉体的泄漏电流为0.33 mA,电绝缘性最好。

关键词: MgO材料, Al₂O₃-SiO₂复合粉, 表面改性, 电绝缘性能, 分散性