Synthesis and Performance of KH-560 Modified SiO2 Insulation Coating

Soft magnetic alloy is the core material of the proton/heavy ion accelerator. To reduce the eddy current loss at high frequencies, the insulating coating needs to be coated on the surface of soft magnetic alloy, and to be followed-up heat treatment (similar to 600 degrees C) to lower the residual stress from defects and dislocations produced in the cold forming process of soft magnetic alloys. Therefore, the insulation coating for soft magnetic alloy should meet the requirement of high-temperature resistance. SiO2 is one of the most common inorganic coating materials, which has good insulation performance and temperature resistance, so it is especially suitable for high-temperature insulation coating. In this work, fabrication process of SiO2 insulating coating was systematically studied. The silane coupling agent 3-glycidyloxypropyltrimethoxysilane (KH-560) was added to the phytic acid-catalyzed tetraethyl orthosilicate (TEOS) and methyltriethoxysilane (MTES) sol to improve the film-forming property. Effect of KH-560 on structure and property of SiO2 coating was analyzed in detail. The results showed that the stability and the film-forming property were improved effectively via adding a reasonable amount of KH-560. When adding amount of KH-560 is 0.04 mol, the as-preared SiO2 coating exhibites excellent film-forming characteristics, corrosion resistance and electrical insulation with sheet resistance of 2.97x10(11) Omega/square at 100 V.