Platinum Metals Rev., 1983, 27, (1), 30
Platinum in Advanced Coatings for Gas Turbines
The use of platinum in corrosion-resistant coatings for the protection of gas turbine blades has been reported in this journal previously (R. G. Wing and I. R. McGill, Platinum Metals Rev., 1981, 25, (3), 94); such coatings are now finding wide application, particularly for aero and marine turbines. More recently, the advantageous use of platinum in ceramic thermal barrier coating systems for advanced gas turbines has been reported at the Third Japan Institute of Metals Symposium on the High Temperature Corrosion of Metals and Alloys, held in November 1982 at Lake Yamanaka, Japan.
Spallation of the ceramic coatings, which are based on stabilised zirconia, arises from the thermal stresses and the corrosive degradation of the bonding layer between the zirconia barrier and the substrate. At the symposium, H. Takeda, H. Baba, T. Suzuki and K. Shimotori of the Toshiba Corporation reported research where the use of a 1.5μ m layer of platinum between the ceramic layer and the bond layer gave rise to a three-fold increase in life of the coating in hot corrosion tests, and a 20 per cent increase in life in thermal fatigue tests. As yet, no explanation for this major improvement in coating durability has been advanced, but these findings could prove to be a significant breakthrough in the development of commercial thermal barrier coating systems for gas turbines.