Metallic glass coatings fabricated by gas tunnel type plasma spraying

Gas tunnel type plasma spraying is a renowned technique due to its greater advantages than other conventional plasma spraying followed by high speed and high energy density plasma jet. Furthermore, this is a simple and novel process for producing dense metallic coatings with and without secondary phases such as oxides and intermetallic phases under selective operating parameters. The present work was undertaken to study the formation mechanism and for examining the metallic glass coating properties formed through gas tunnel type plasma spraying process. For this purpose, Fe based, Zr based and Ni based metallic glass coatings were individually deposited by gas tunnel type plasma spray torch at optimum operating conditions with two different input currents (300 and 400 A). Phase and microstructure formations were examined and the results were correlated with the input current. Similarly, mechanical properties and electrochemical corrosion properties of each coating were examined and the results were correlated with the existing phase and the microstructures of the coatings. The examined results revealed that the Fe based metallic glass coatings have relatively less porosity (3-4%) and crystalline phase fraction (9-14%). These coatings also exhibit excellent sliding wear resistance (2.77 × 10−6 mm3/nm−1) and electrochemical corrosion resistance against 3.5% NaCl solution.