Copper catastrophic oxidation: Theory and mechanisms

Copper and its alloys with transition metals (as good conductors of electricity and heat) are extensively used in electrical industry, electronics, and cooling systems and can be the subject of surface degradation by oxidation. In certain circumstances, surface degradation of copper occurs catastrophically. Predicting catastrophic oxidation kinetics and developing protective technology require understanding the mass transfer mechanisms in the solid/liquid/gas composite scale formed on the copper surface during catastrophic degradation. However, these mechanisms are not clear enough. The role of capillary forces in the mass transport process in the composite scale with a high density of solid/liquid and liquid/gas interfaces has not been established. Here, we show the significant contribution of both electrochemical and solutocapillary forces to mass transfer and suggest the mechanisms, involving selective transport of ions, gas bubbles, and liquid, and their relationships with the microstructure of the composite scale. The bubble nucleation is discussed.