Shear thickening polishing of the concave surface of high-temperature nickel-based alloy turbine blade

Abstract

High-temperature nickel-based alloy, which is a valuable crucial material for fabricating functional components, is commonly used to fabricate turbine blades. However, the concave surface of the turbine blade is much difficult to be polished. In this work, shear-thickening polishing (STP), which employed the shear-thickening mechanism of non-Newtonian power-law fluid, was utilized to achieve high efficiency and high-quality polishing of the concave surface of the high-temperature nickel-based alloy turbine blade. The finite element simulation of the pressure and velocity distribution on the concave surface during STP process was carried out by ANSYS, and the effects of different polishing angles, polishing velocities, pH values of polishing slurry and Fenton's reagent on the surface morphology and roughness of the workpiece were investigated by experiment. The comparison between simulation and experimental results indicated that the suitable polishing angle is 45°. The best surface can be obtained with a pH value of 6.5. With the increase of the polishing speed, polishing efficiency improved gradually. The workpiece surface was improved by adding 0.5% hydrogen peroxide (H2O2) and 0.15% FeSO4 in the polishing slurry. In the final, surface roughness of the turbine blade was reduced rapidly from Ra = 72.3 nm to Ra = 4.2 nm after 9 min polishing under the appropriate conditions. The research results provide reference and basis for high-temperature nickel-based alloy turbine blade polishing.