Blast cleaning of gas turbine components: deposit removal and substrate deformation

The effectiveness of glass and stainless steel spheres in the blast cleaning of stationary gas turbine components was evaluated as a function of particle size, speed, impact angle, and standoff distance. The overall objective was to maximize the rate of deposit removal while minimizing substrate deformation. It was found that deposit erosion and substrate deformation were strong functions of particle stream power, particle kinetic energy, and impact angle. The erosion of deposits on compressor and turbine stage components exhibited brittle characteristics, while substrate deformation was ductile. For this reason, an impact angle of 90° to the surface was optimal. Substrate deformation increased with average particle kinetic energy, independent of stream power. Deposit removal with glass media increased with stream power. Blasting with the stainless steel media, which was softer than the substrate, prevented deformation while still removing deposits.