Effect of Modified Silica Sol Sealing Agent on the Insulation Properties and Microstructure of Porous Al2O3 Ceramics.

The organosilicon modified silica sol sealant was prepared by modifying silica sol with methyltrimethoxysilane and dimethyldimethoxysilane, and the porous Al2 O3 ceramic sheets were sealed by impregnation and heating curing. The effects of curing temperature and time on the insulation properties of porous Al2 O3 ceramics sheets were studied, and the microstructure of porous Al2 O3 ceramic sheets before and after sealing was characterized. The results show that the optimal conditions are that curing temperature of 120 and curing time of 60 min, at which the DC and AC breakdown voltage of the Al2 O3 ceramic sheets reach the maximum values of 10. 76 kV and 6. 01 kV respectively, and the insulation resistance of 1,000 V reaches more than 9,999 MΩ. The surface of the Al2 O3 ceramic sheet is a modified silica sol coating, which is compact, non-porous and tightly bound to the matrix. The coating thickness is about 25 mm, the surface water contact angle is increased to 86. 93°, and the depth of the layer is about 10 μm. [ABSTRACT FROM AUTHOR]