1 Copyright © 2014 by ASME Proceedings of the ASME Turbo Expo 2014 GT2014 June 16-20, Düsseldorf, Germany GT2014- 26325 OPERATION OF A BURNER RIG FOR THERMAL GRADIENT CYCLING OF THERMAL BARRIER COATINGS J.P. Feist Sensor Coating Systems London, United Kingdom P.Y. Sollazzo Sensor Coating Systems London, United Kingdom C. Pilgrim Sensor Coating Systems London, United Kingdom J.R. Nicholls Cranfield University Bedford, United Kingdom ABSTRACT Thermal barrier coatings (TBC), in combination with sophisticated cooling systems are crucial for the operation of highly efficient gas turbines. New generations of coatings will need to show increased cycling capability as a future energy mix will contain a high proportion of renewable energy which will be subject to rapid changes in supply. This will require gas turbines to be on stand-by to fill shortages in power supply with short notice. Furthermore, higher operating temperatures are sought to improve the efficiency of the engine. It is, therefore, an aim of the industry to find a coating composition or structure which will enable the operation at temperatures greater than 1250°C and with high cycling capability. Test methods are required to meet these new operating conditions to validate new coatings. The maximum temperature limit of commonly used isothermal or cyclic oxidation tests is usually the temperature at which the substrate will start to significantly oxidise. However, there is the technical need to test the ceramic top layer at elevated surface temperatures up to 1500°C while keeping the substrate ‘cool’. Such capability would allow the effects of ceramic sintering, and deposit induced damage to be assessed at the TBC surface. This only can be performed on a complete coating system, when a thermal gradient is established throughout the coating. This paper reviews a burner test facility, designed and built by Sensor Coating Systems Ltd. (SCS), which combines severe and frequent cycling with the exposure of the coating to high surface temperatures and active cooling of the substrate. Further, this test can include thermal shock by active cooling of the surface at the end of each cycle. The paper will consider different operating conditions and will review experiences in building and operating the rig, including results from thermal barrier coating tests on electron beam physical vapour deposition (EBPVD) and atmospheric plasma spray (APS) samples. Further, the rig is capable of testing optical techniques such as pyrometry and thermographic phosphor thermometry for measuring surface temperature in controlled laboratory conditions and example of this will be presented. The paper also will reflect on the ISO 13123:201 standard for this type of test. INTRODUCTION Efficiency increases in turbine operation have been achieved mainly through increasing firing temperatures. Apart from advanced high temperature alloys and sophisticated cooling methods, thermal barrier coatings (TBCs) have played a major role in this development. Gas temperatures in today’s turbines are above the melting point of the metal components – vanes, blades - in the hot section, the most expensive part of the turbine. TBCs in combination with internal cooling allow components to survive higher temperatures while achieving acceptable life times. Future changes in the global energy market and in particular the increasing share of renewable energies in the energy mix will result in changing operating conditions of gas turbines when used as back-up power supplies. Electricity generation from renewable energy sources can change quickly dependent on, for example weather conditions and hence will require back-up solutions to avoid power outages. Gas turbines are best suited to efficiently provide the energy at short notice and, if necessary, quickly reduce power output when demand is reduced. This will consequently lead to increased cycling and hence an appropriate test platform is required. The coating community has not yet developed a standard methodology to test all relevant parameters simultaneously. The main ideas range from isothermal or cyclic oxidation of samples in a furnace to thermal mechanical fatigue tests. Further, additional corrosion and erosion tests have been