Wear analysis of chromium based thermal spray protective coatings and hard facing on zero tillage blade material in simulated conditions

The study experimentally investigated the effect of wear-resistant coatings as well as hardfacing by manual metal arc welding MMAW on EN-19 alloy steel which is used in the manufacture of superseder blades, also termed as zero tillage blades. After an extensive literature review, Cr2O3 based thermal coating and hardfacing were selected for deposition of a wear resistant layer over the surface of EN-19 alloy steel with the application of rodo jet gun spray technique and MMAW process. Experimentation was conducted on test samples using variable sliding velocities as well as load conditions with combinations carved out with the help of Taguchi’s L9 array. After experimentation on Pin on Disk tribometer, samples were analysed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Uncoated, coated as well as hard faced samples were subjected to different sliding time intervals (5, 5, 10, 10, 15, 15, and 30 minutes) under sliding speeds (0.5, 1, and 2 m/s) at a different load value of 30, 40 and 50 N. Wear rate in terms of cumulative weight loss was also evaluated for all the test samples. The results were corelated with the help of SEM micrographs of the worn surfaces. It was observed that the samples coated by rodjet spray technique exhibited significantly less weight loss as compared to hardfaced and bare sample pins. Hence, the wear resistance of Cr₂O₃ based thermal coating was found to be better than the hard facing coating on substrate made up of EN-19 alloy steel and it was concluded that a new advanced technology named as the rodo-jet thermal spray process proved out to be a good and reliable technique for minimizing wear of tillage tool material.