Processing and Characterization of Plasma Spray Coatings of Glass Microspheres Premixed with Al2O3 Particles

摘要

Various ceramics and metals are being deposited as functional, protective, and near-homogenous coatings on engineering components by exploiting the characteristic properties of plasma medium. Such coatings are known to exhibit improved wear, thermal, and corrosion resistance. Although a lot of studies have been reported on coatings made up of a large number of metals and ceramic particles, hardly any effort is made to coat glass microspheres on metals despite their high hardness. In view of this, the present work was undertaken to study the preparation and characterization of a new class of coatings made up of borosilicate glass microspheres (BGM) premixed with micro-sized aluminum oxide (Al2O3) in different proportions. Deposition of these BGM and BGM/Al2O3 coatings is carried out at five different levels of torch input power. Coatings are characterized in terms of their thickness, hardness, adhesion strength, and porosity. The coatability of BGM and the BGM/Al2O3 mixture on metallic substrates is assessed by evaluating the coating deposition efficiency. This work reveals that the torch input power and the Al2O3 content in the feedstock affect the major coating characteristics, and premixing of Al2O3 with BGM results in better coating properties.