Review of mechanisms of erosion-corrosion of alloys at elevated temperatures

Erosion-corrosion of materials at elevated temperatures is a major problem in various industrial processes which range from some of the more advanced coal-conversion processes, to the turbine blades of jet engines. The extent of wastage in such environments is dependent on a wide variety of parameters which include properties of the impacting particles, target material and the corrosive environment. At this stage various laboratory studies have been carried out and patterns have emerged of the effects of the main erosion-corrosion variables on alloy wastage. One of the most consistent results from the laboratory studies has been on the effect of temperature. The wastage has been seen to increase to a critical temperature and subsequently decrease with further increases in temperature. This curve has been shown to shift to higher temperatures with increasing oxidation resistance of the alloy, and to higher temperatures and wastage rates with increasing particle impact energy. Other variables which may affect this curve are particle angularity, nature of the corrosive environment, impact angle and composition of the oxide scale formed during the erosion process. This paper reviews some recent laboratory erosion-corrosion results. The general trends in alloy wastage as functions of the main erosion-corrosion parameters are shown