The corrosion of gold and silver coated copper by the thermal degradation products of chloroprene and silicone rubber

The corrosion of gold and silver coatings on copper by the thermal degradation products (100°C) of chloroprene and silicone rubber has been studied by mass-spectrometry, secondary ion mass-spectrometry (SIMS) of interaction products and petrographic analysis of corrosion films. The volatile products of degradation of both organic materials greatly influence the protective coating of gold and silver; the composition of chloroprene rubber is more aggressive and along with decomposition of the protective coating, corrosion leads to the partial removing of the coating with simultaneous corrosion of a copper substrate. Formic acid vapours and chlorine are the most corrosion active components of the atmosphere. These substances produce the unstable gold and silver salts, chlorides and formates, extracting during their degradation fine dispersed crystals of a secondary metal, these being one of the main corrosion products.