A significant reduction of CO2 emissions is expected by increasing the efficiencies of the steam turbines to s > 50% which can be achieved by moving from subcritical conditions (180 bar/540°C) to an ultra-supercritical regime of operation (300 bar/620 - 650°C). However, turbine components face various challenges, related to higher temperatures such as material failure due to high temperature oxidation, and phenomena such as creep and erosion caused by descaled fragments.

Until recently the PVD route has not been exploited for this application. The main reason being the porous structure of the state-of-the-art coatings, especially when monolithically grown, inherent to their growth mechanism. However, HIPIMS deposited CrN/NbN coatings utilising nanoscale multilayer structure developed at the National HIPIMS Technology Centre at Sheffield Hallam University have shown a promising performance when subjected to various types of high temperature tests in an aggressive pure steam environment, (download PowerPoint slides for more information (PDF, 1.8MB)).