An Overview on Erosion of Hydraulic Turbine Materials and Thermal Spray Erosion Resistant Coatings

High-performance materials of today are required to possess a combination of properties such as thermal and wear resistance, chemical stability, corrosion resistance as well as excellent mechanical properties. Selection of materials for slurry erosion resistance for the hydraulic turbines is an area of considerable interest in the current times. The problem get further aggravated where the water may contain a high burden of solid particles for example during monsoon seasons. Erosion is more likely to be a problem for turbine blades, needles and nozzles in the hydraulic Machinery which have to tolerate perpetual high-speed water (with or without solid particles) impingement. A large number of candidate coatings with different compositions and monolithic materials have been investigated as possible means of reducing erosion, for example monolithic and cermet coatings of hard carbide phase tungsten carbide (WC) embedded in ductile matrix; typically coating system consisting of WC–Co, WC–Co–Cr, WC–Ni–Cr and FeCrAlY–Cr₃C₂ and thermally sprayed metal oxide ceramics. In this paper, attempt has been made to present an overview of basics of erosion and the recent work done by researchers on the erosion of bare and thermally sprayed coated turbine materials.