Diffusion Coatings

This article describes the widespread use of diffusion coatings for elevated-temperature protection of the turbine components for aircraft engines and gas turbines. The principles of pack diffusion coating, namely, aluminizing, chromizing, and siliconizing, are discussed. The article presents information on the coating formation mechanism of superalloys and explains the steps involved in a typical pack cementation process. It concludes with information on the processing procedures and properties of pack aluminized steels.