Dental porcelain/Ni alloy interface reactions and their effective prevention.

In a Be-bearing Ni alloy porcelainized without preoxidation, Be diffuses to the interface, oxidizes, and oxygen is supplied by the atmosphere at the porcelain surface and by reduction of SiO2 at the porcelain-alloy interface. On the alloy side of the interface, pits develop locally and near them Ni and Cr oxidize. In the oxide, Ni and Si are reduced to form nickel silicides. Preoxidation of the alloy prevents Be oxidation and Si reduction for several hours of porcelainization.