Protecting Gas Turbine Components

One of the major maintenance problems for gas turbine engine operators is the degradation of high pressure turbine blades and vanes. The Australian Department of Defence was experiencing unacceptably high rejection rates of these components in one of its high performance engines as a result of severe hot corrosion attack. Accordingly a programme was initiated to find a more durable coating than the conventional aluminide coating supplied for the first-stage blades by the engine manufacturer. The coating chosen for the trial was a platinum-modified aluminide coating. Metallographic examination of both coating systems after 750 hours of service in an operational aircraft clearly established the superiority of the platinum-modified coating. This coating has now been adopted by the Australian Defence Force as the specified coating for first-stage blades in this engine.