On deposition and characterisation of MoS _x -Ti multilayer coating and performance evaluation in dry turning of aluminium alloy and steel

Abstract

In recent times, MoS _x or MoS _x -based composite solid lubricant coatings have demonstrated some potential in environment-friendly dry machining. However, most of the previous studies were restricted to drilling and milling operations. In the current research work, MoS _x -Ti coating with TiN underlayer was deposited using pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS) technique. The deposited film was characterised using field emission scanning electron microscopy (FESEM), grazing incidence X-ray diffraction (GIXRD), scratch adhesion test and Vickers microhardness test. The performance test of the coating was carried out in dry turning of ISO AlSiMg aluminium alloy and IS 80C6 high carbon steel with uncoated and MoS _x -Ti (with TiN underlayer) coated cemented carbide inserts. Results indicated that coated tool arrested the tendency of formation of built-up material during machining of aluminium alloy resulting in superior workpiece surface finish compared to that for uncoated tool. During dry turning of high carbon steel, the same coated tool resulted in reduction in axial cutting force in the entire range of cutting velocities (32 to 230 m/min). During machining at higher cutting velocity the same coating provided effective diffusion barrier by restricting crater wear.