Abrasivity testing of filled epoxy resins

The epoxy resins used to encapsulate automotive ignition coils and other high voltage electrical devices typically contain filler material in order to reduce the cost and to improve the material properties of the cured epoxy. However, these filler materials are abrasive and, as such, detrimental to epoxy encapsulation equipment. The abrasivity of two epoxy resins with different filler types was quantified using the ASTM G 75 Slurry Abrasion Response Number test method. The testing showed the type of filler material used greatly affects the wear of materials typically used in the construction of epoxy encapsulation equipment. Fillers with a lower Mohs hardness cause less wear. High wear areas in encapsulation equipment should be built with high hardness materials. In particular, chromium oxide ceramic shows promise as a wear reducing coating.