电熔镁砂涂层制备技术及防水性能研究

电熔镁砂作为高导热、耐高温的绝缘材料，在潮湿的空气中易水化变质而失去绝缘性。采用涂层法，以电熔镁砂、硝酸铝、三聚氰胺为原材料，在通氮气、1 250 ℃条件下，对电熔镁砂颗粒进行包覆。采用扫描电子显微镜（SEM）观察电熔镁砂颗粒表面已形成涂层，通过X射线衍射仪（XRD）分析表明包覆层为镁铝尖晶石，且无氮化镁、氮化铝、氮化碳。经过孔隙比表面积分析仪分析，完全包覆的电熔镁砂颗粒比表面积与之前相比有所增大。采用真空吸水干燥法检验吸水性能，检验结果显示，经过包覆的电熔镁砂颗粒吸水率降低了92.97%，最低吸水率达到0.167 2%。实验循环7次，吸水率仍能达到0.17%以下，该项研究为电熔镁砂防水技术提供了一条新途径。

Study on preparation technology and waterproof property of fused magnesia coating

Fused magnesia，as an insulating material with high thermal conductivity and high temperature resistance，is prone to hydration deterioration and loss of insulation in humid air.The coating method was used to coat the fused magnesia，aluminum nitrate and melamine as raw materials under the condition of nitrogen and 1 250 ℃.Scanning electron microscope（SEM） was used to observe the formation of coating on the surface of fused magnesia particles.X-ray diffraction（XRD） analysis showed that the coating layer was magnesium aluminium spinel，and there was no magnesium nitride，aluminum nitride，carbon nitride.Through pore specific surface area analysis，the specific surface area of fully coated fused magnesite particles was increased by comparing to the previous.Vacuum water absorption drying method was used to test the water absorption performance.The test results showed that the water absorption rate of coated fused magnesite particles was reduced by 92.97%，and the lowest water absorption rate reached 0.167 2%.The water absorption rate could reach less than 0.17% after 7 cycles.This study provided a new way for fused magnesia waterproof technology.