On the Erosion of Material Surfaces caused by Electrical Plasma Discharging

Abstract

ABSTRACTThe erosion of material surfaces produced by electrical discharges plays an important role on the degradation of many electrical devices, such as electrical contacts, switches or spark plugs. A discharge produces an extreme and concentrated flow of energy into the material that heats it and can even cause melting or vaporization. The plasma pressure may cause an even greater removal of material by the emission of droplets of molten material, producing craters in the surface of the material. In this contribution the microscopic erosion mechanisms on RuAl basis intermetallic compounds are compared with those for pure metals. Single discharge experiments at high pressure were done and the erosion structures were characterized with white light interferometry and scanning electron microscopy. The effects of microstructure on the surface erosion are discussed on the basis of different samples of RuAl. In certain high temperature applications, formation of oxide scales is an important process that may influence the discharge characteristics and erosion mechanisms. These effects are discussed on results in pre-oxidized samples. It was shown, that the surface can be additionally stabilized by controlling the protecting oxide coatings.