The High Temperature Erosion/Corrosion Behavior of Industrial Thermally Sprayed Coatings

Abstract

Abstract There are numerous industrial applications where materials are subjected to simultaneous high temperature oxidation/corrosion and wear (such as erosion). This combination often leads to accelerated degradation. Specific industries include: chemical, waste incineration, power generation and paper/pulp with typical applications including boilers and cyclones. Previous studies have established wrought material compositions and microstructures which can resist these environments. In searching for cost-effective industrial solutions, surface coating via thermal spray becomes attractive. However, the microstructural complexity of such coatings can make the simple extrapolation of bulk material behavior to these coatings dangerous. If these coatings are to be used more widely, a greater understanding of their high temperature erosion/corrosion behavior and the influence of coating process is required. A range of Fe-and Ni-based alloys and thermal spray techniques were studied under various high temperature erosion/corrosion conditions. The critical erosion parameters of impact angle (30° to 90°) and temperature (up to 550°C in air) have been studied in an atmospheric fluidized bed test rig environment, using Al2O3 erodent at a typical impact velocity of 4m/sec and conventional high temperature erosion test equipment. The important microstructural and mechanical features of the coatings and the effect of the thermal spray process are discussed in terms of their high temperature degradation mechanisms.