Study of the structure and adhesive properties of ceramic coatings prepared by plasma spraying
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STUDY OF THE STRUCTURE AND ADHESIVE PROPERTIES OF CERAMIC COATINGS PREPARED BY PLASMA SPRAYING D. Jankura, V. Bačová, and D. Draganovská We study the influence of technological parameters on the formation and structure of ceramic coatings based on Al2 O3 and deposited by plasma spraying. We present the results of investigations of the adhesive properties of plasma-sprayed coatings based on Al2 O3 and Zr SiO4 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 highquality melting of ceramic materials based on Al2 O3 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 Al2 O3 and Zr SiO4 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.
One of possible applications of ceramic materials in the engineering practice is the formation of ceramic coatings on the metal substrate of structural elements which, in this way, gain some specific properties, such as corrosion resistance, wear resistance, resistance against thermal stresses, etc. Hot spraying of powder ceramic materials is the basic technology used for the preparation of these coatings. Form the viewpoint of heat capacity and temperature, plasma spraying seems to be a very advantageous technology. Basic information on the process of plasma spraying can be found in [1–3]. The major advantages of the process of plasma spraying explaining its relatively universal utilization include: — a much wider range of sprayed materials (from high-melting metals, oxides, and alloy combinations to plastics) due to high temperatures of plasma, while its enthalpy can be controlled by using various stabilization media; — a negligible thermal effect on the basic material (circa 200°C), which guarantees the dimensional and structural stability of the substrate and makes it possible to use a great variety of materials: metals, alloys, ceramics, concrete, wood, graphite, etc.; — a possibility to form coatings with micron-to-millimeter thicknesses on small and large areas; Technical University in Košice, Mäsiarska, Košice, Slovakia. Published in Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 2, pp. 62–70, March–April, 2008. Original article submitted April 17, 2007. 222
1068–820X/08/4402–0222
© 2008
Springer Science+Business Media, Inc.
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