Erosion behavior of marble dust-coated mild steel substrates

Abstract

The present work reports on the deposition of coatings of marble dust, an ornamental stone waste, on mild steel using the high-velocity oxy-fuel spraying route and then on its erosion behavior. Coating deposition is carried out at five different spray distances (50, 100, 150, 200 and 250 mm). The coatings are characterized in terms of their deposition efficiency, thickness, adhesion strength, micro-hardness, and erosion responses under different test conditions. It is observed that while the coatings deposited at 100 mm spray distance possess maximum deposition efficiency of 52% and maximum thickness of about 256 micron, the ones deposited at the spray distance of 200 mm possess maximum adhesion strength and micro-hardness of about 48.3 MPa and 493 Hv, respectively. Thus, the coating deposited at 200 mm spray distance with maximum adhesion strength and micro-hardness is chosen for the erosion test. Erosion trials are conducted using a solid particle erosion test rig following ASTM G76 as per L-16 orthogonal array of the Taguchi experimental design. It reveals that the impact velocity, erodent temperature and impingement angle in that sequence are significant in affecting the erosion rate. Steady-state wear experiments at different levels of these significant control factors reveal that the erosion rate attains a maximum value at the impingement angle of 75 degrees, assuring the near-brittle response of the coating to the erosion wear. The possible mechanisms of wear loss are identified from the morphologies of the eroded surfaces.