Diamond Jet (HVOF) Applied Abradable Coatings for Turbine Fan Case Application

An aluminum-silicon alloy/polyester abradable coating for clearance control applications (ie: first stage compressor seals of gas turbine engines) has been produced by using the Diamond Jet process, a High Velocity Oxy-Fuel (HVOF) system. The objective of this paper was to develop effective spray parameters for optimized coating properties for turbine fan case applications by using a statistical method known as Taguchi Analysis. The properties evaluated were coating hardness, bond strength and microstructure. By using Taguchi Analysis the relationship between the various key parameters and coating properties can be determined.

For production verification of parameters developed by using Taguchi Analysis, a turbine fan casing was sprayed with the effective spray parameters. The results indicate that the fan case coating properties meet all the aerospace specification requirements.