In modern cast part impregnation, impregnation agents based on (meth) acrylates are predominantly used today. There are still technologies based on water glass (sodium silicate) as well as on epoxy and polyester, which are hardly used anymore.
Water glass is actually only used there when it comes to workpieces that are exposed to very high temperatures (> 400 ° C) and thus the modern (meth) acrylate-based impregnating agents can no longer be used due to their temperature resistance.
All impregnating agents are based on similar basic monomers. There are two main groups that can be differentiated based on their curing method:
Anaerobic impregnation agent
These impregnating agents harden at room temperature, which happens relatively slowly. Workpieces impregnated in this way can therefore only be pressure-tested after 48 hours.
It is usually used in simple, small wet vacuum systems (WV) and in some systems a type of "accelerator bath" is used, which can shorten the curing process.
This technology is less used in the field of cast part impregnation, since here the workpieces often have to be checked for leaks immediately after impregnation.
The basic performance of the anaerobic impregnating agents is in no way inferior to the better-known thermosetting resins.
Thermal curing impregnation agent
In contrast to the anaerobic impregnation agents, the hardening is forced by the external supply of energy.
Hardening is based on the decomposition of initiators under the influence of heat (usually 90 degrees Celsius)
The heat is mostly supplied by a hot water bath, since this ensures very good energy storage and heat transfer.
As soon as the workpiece - and thus also the infiltrated impregnating agent - reaches a certain temperature, curing begins. The required temperature can be set using the concentration and / or selection of the catalysts. In this way you can vary both the starting point of the hardening and the gel time.
The required system technology is basically identical for all thermosetting resin types and consists of the autoclave, a recovery unit, a washing station and a curing station. The impregnated workpieces can then be checked for leaks immediately.