1. College of Materials Science and Engineering, Xi’an University of Architecture and Technology，Xi’an 710055，China
2. Puyang Refractories Group Co, Ltd，Puyang 457100, China
To improve its insufficient electrical property and make it more suitable for the electric heating tube manufacturing industry after modification, the plain electrical grade magnesium oxide powder was modified by adding silica,additive used in electrical grade magnesium oxide powder and silicone oil.Therefore, 25 groups of ratios were designed to carry out combined experiments. On the basis of the orthogonal experiment method. Analyze the optimal ratio under a single indicator (normal withstand voltage, leakage current and heating withstand voltage) with the range method. Also the matrix analysis method was used to analysis and optimize to obtain the optimal ratio,and the index value prediction method was used to predict the electrical property of the final ratio of modified electrical grade magnesium oxide powder. Finally, the results showed that the content of silica is the main influencing factor when the normal and heating withstand voltage is used as the indicator. However, when using leakage current as an indicator, the content of silicone oil is the main influencing factor, followed by the content of additive used in electrical grade magnesium oxide powder. In addition, the final parameters of the optimally selected backfill are as follows: 0.25wt% of silica,2wt% of additive used in electrical grade magnesium oxide powder,0.25wt% of silicone oil. Its estimated values of electrical properties of the final ratio of modified electrical grade magnesium oxide powder are normal withstand voltage of 3365 V, leakage current of 0.112 mA, heating withstand voltage of 2399 V.