Study of the structure and adhesive properties of ceramic coatings prepared by plasma spraying

We study the influence of technological parameters on the formation and structure of ceramic coatings based on Al₂O₃ and deposited by plasma spraying. We present the results of investigations of the adhesive properties of plasma-sprayed coatings based on Al₂O₃ and ZrSiO₄ that form tribological couples with 19,436 and 12,050 steels and polyamide. It is shown that the parameters of an A-160 plasma torch with aqueous plasma stabilization are suitable for the high-quality melting of ceramic materials based on Al₂O₃ if we use powders with particles 40–100 μm in size and perform spraying from a distance of 200–600 mm. Ceramic layers are formed by three types of particles of different shapes with different arrangements. Defects in the structure of the layers (pores, hollows, branched cracks, and large particles) deteriorate the properties of the coatings. The coatings based on Al₂O₃ and ZrSiO₄ exhibit the best properties under the conditions of abrasive wear, and this material, in combination with 19,436 steel, is suitable for application in friction couples. The degree of wear corresponds to the the value of the friction coefficient for the investigated tribocouples determined by the hardness of the material surfaces in the couple. The ceramics-polyamide couple seems to be quite promising due to the low friction coefficient and minimum wear. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 2, pp. 62–70, March–April, 2008.