Effect of Varying Load on DLC/AlCrN-Based Coated AISI D2 Die Steel at Constant Sliding Velocity

This study has been made to limit the sliding wear by employing advanced protective nano coatings by using DC magnetron sputtering Physical Vapour Deposition technique. Three advanced nano coatings viz. Diamond-Like Carbon (DLC), composite AlCrN coating and AlCrN/TiAlN multilayered coatings were selected for present work due to their enviable wear resistant characteristics. Coatings were deposited on AISI-D2 die steel by traditional DC magnetron sputtering physical vapour deposition technique. The as deposited coatings were characterized with surface roughness, microhardness, porosity and microstructure. The X-Ray Diffraction (XRD) and field mission scanning electron microscope (FESEM with EDAX) techniques have been used to describe various phases established after coating deposited on the surface of the substrate. Subsequently, sliding wear and friction tests were conducted in accordance with ASTM standard G99-03, under scrutiny variation of load and time and at constant sliding speed. Cumulative wear volume loss and coefficient of friction were formulated for coated as well as uncoated/tempered specimen at a constant speed of 1 m/s and varying load of 25N and 50N. The results from experimentation were analysed with SEM micrographs and Energy dispersive spectrum to analyse the adaptability of coating for base materials, wear behaviour and friction behaviour of coated and uncoated/tempered substrates. The results have shown adaptability of advance nano-coatings for AISI D2 die steel. The generation of oxide layer during wear process provides wear resistance to the AlCrN-based coatings. No thermal instability has been observed in nano-coatings at low temperature generated while experimentation and that is under working range of cold forming processes. It is observed that there is relevant decrease in frictional force by the application of DLC coatings while AlCrN/TiAlN has provided much better wear resistance.