Production of monolayer grinding wheel by novel explosive spray coating method

Abstract

Explosives are generally used for welding and forming in the manufacturing processes. However, it is hard to find work-related coatings where explosive has been used. In the present study, the flash powder is used as an explosive material. This flash powder is coated on a round mild steel surface by using a novel explosive coating setup to fabricate a monolayer grinding wheel. In the first section, the coating is performed on the flat mild steel substrate to achieve optimized process parameters of the explosive coating setup. Process parameters are optimized by the varying stand of distance (SOD), ignition point system, and relative quantity of the flash powder to obtain maximum hardness. The coatings are characterized in terms of thickness, crystalline phase, microstructure, roughness, hardness, and adhesion by using an optical microscope, X-ray diffractometer (XRD), Field emission scanning electron microscope (FESEM), stylus profilometer, Vickers micro hardness tester, and scratch tester respectively. The coating obtained with 4 gm flash powder (2 gm each of aluminum (Al) and barium nitrate Ba(NO3)2), double point ignition system, and SOD of 80 mm indicated the highest hardness around 950 HV0.05 and coating thickness of 85 µm. XRD results of the coating obtained from optimized process parameters indicate the presence of barium (Ba), Al, and barium aluminate (BaAl2O4) phases. Non-uniform coating with unmelted Al particles is observed through FESEM and EDS (Electron Dispersive Spectroscopy) analysis. Heat treatment is also carried out on the coated samples obtained from varying aluminium compositions to analyze the hardness. In the second section, a cBN monolayer grinding wheel has been successfully fabricated by spraying flash powder along with cBN grits.