High Voltage Insulators: Solids
As you no doubt expected, here is the final installment in this brief introduction to high voltage insulators, solids, of course. However, this is limited to common encapsulating solids.
For best results, insulating materials should be homogeneous, and should not contain air spaces or moisture. This is especially critical with solids, as corona and arcing can occur in air voids.
Epoxy is best when you need excellent adhesion. It has good thermal conductivity for a solid.
Silicones come in two basic types. The curing process of additive cure silicones can be accelerated with the addition of heat, so that it can complete in an hour. Condensation cure silicones can take 24 hours or more to cure, however, the adhesion properties are better. For both types, adhesion can be an issue.
Other potting materials include tar (low cost) and polyurethane.