PRELIMINARY RESULTS ON FINISHING OF WC-Co COATING BY MAGNETORHEOLOGICAL FINISHING PROCESS

Thermal spray coating has the ability to enhance the lifetime of engineering components by reinforcing the surface properties. The surface roughness of the as-sprayed coatings needs to be suitably finished for its end use. The nanofinished WC-Co coatings are widely used in aerospace and automobile industries. In this present investigation, surface grinding followed by the magnetorheological finishing (MRF) processes is employed for finishing of WC-Co coating. Boron carbide (B4C) powder is used as the abrasive particles in the MRF process. MRF spot finishing technique is performed on the ground coating. The plastically deformed layer from the ground surface is removed completely by the gentle mechanical abrasion of MR fluid ribbon. The surface roughness and volume of material removed are measured over the finishing time. It is perceived that the surface roughness of the finishing spot is increased after a threshold machining time. This is attributed to the aging of MR fluid and the mechanical abrasion of wear debris. The experiment is also performed with the assistance of Murakami's reagent to perform etching and finishing, simultaneously. A comparatively higher finishing rate is observed in this case.