ICMCTF2001 Session A1-1: Coatings to Resist High Temperature Corrosion

Superalloy samples were coated using a low activity platinum aluminide applied by chemical vapor deposition (CVD). Different platinum thickness values were obtained on each sample by electroplating prior to CVD aluminizing and resulted in an array of platinum concentrations in the ensuing coating. The aluminide coating applied was a single phase, low activity platinum aluminide, with platinum concentrations varying from 10-40 weight percent.

The samples were then subjected to cyclic oxidation testing at 1175°C until failure. As expected, it was discovered that higher concentrations of platinum resulted in a coating more resistant to degradation during the cyclic oxidation testing. The dependence of platinum displayed an approximately linear relationship to cyclic oxidation life in the test cases cited. Compositional traces of coating and alloying elements were tracked before and after the oxidation testing. The results were compared to previous research on oxidation resistance of bare alloys and of those in previous classical literature on two-phase platinum aluminide coatings. The ramifications of diffusion of many of the alloying elements are discussed with regard to their relative effects on oxidation resistance of the coating, and for gas turbine hardware in service conditions. }