Abstract

Slurry-handling equipment and pipelines particularly used in coal processing and mining industries are continuously exposed to the Impact of liquid-borne solid particles, resulting in progressive damage and loss of material. Cost-effective solutions to slurry erosion in aqueous media have been mainly limited to austenitic stainless steels, although coatings have been proposed. This work was aimed at evaluating the slurry erosion resistance of arc-sprayed coatings and determining what improvement IS achieved after laser melting. Multiphase and Type 316 stainless steel arc-sprayed coatings were obtained by arc spraying in air solid and cored wires. The surface of arc-sprayed coatings was melted using a pulsed Nd-YAG laser producing 1.06 µm wavelength radiation. Arc-sprayed and laser-melted coatings were slurry erosion tested at impact angles of 25° and 90° in a laboratory slurry jet erosion device using quartz sand as erodent. The evaluation of wear damage was done with a laser profilometer. Scanning electron microscopy and X-ray diffraction analysis were used to evaluate the microstructural changes which occurred after laser surface melting. Multiphase arc-sprayed coatings were more slurry erosion resistant than Type 316 stainless steel coatings. Improvement in slurry erosion resistance, particularly at the impact angle of 90°, was achieved by laser melting multiphase arc-sprayed coatings. Although deep microstructural changes occurred within coatings upon laser melting, the removal of stringers between sprayed platelets by laser melting was found responsible for the increase in slurry erosion resistance of multiphase laser-melted coatings.

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