Abstract

High temperature steam and gas turbines use a range of materials to confer high strength and high temperature creep and wear resistance. For steam turbines, steel and nickel based alloys are commonly used, whilst gas turbines utilise titanium alloys and nickel-based super alloys. In gas turbine applications, steels are only used for bearings and shafts, due to the compromise between strength, hardness and mass. For both gas and steam turbines, coatings and surface treatments are applied to: enhance reliability, give increased oxidation resistance, and to improve wear and erosion performance. Surface coatings and treatments ideally are considered at the design stage, where the interaction between the coating, the bond coating and substrate can be considered as interdependent. Bond coats are particularly important in providing adhesion to prevent spallation of the coating during thermal cycling. This seminar reviews the role of the material and/or coating’s microstructure in conferring high temperature wear and erosion properties.