Abstract:

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.

Key words: coating methods, magnesium aluminium spinel, water absorption rate, fused magnesite