The parameters of the plasma torch of AC-160 type with a constant, uncontrolled electric input are suitable for reliable melting of Al_2O_3 based ceramic materials in the form of powder with the particle size of 40... 100 mu m, when spraying distances from 200 to 600 mm are used. To obtain the optimum technological conditions, it is necessary to equip the torch with a feed mechanism and with a controlled input. In such a way the most suitable thermal conditions for the optimum shape deformation of sprayed particles can be achieved. Ceramic coatings consist of three types of particles which differ from each other in their shape and compactness. Ceramic, sufficiently heated material produces relatively homogeneous coatings with few defects: voids; pores; branched cracks. Cohesive and adhesive properties of ceramic coatings are also degraded by a peculiar type of large particles which appear in the coating due to insufficiently sieved and prepared added material. Among the investigated ceramic Al_2O_3 and ZrSiO_4 based coatings, in tribological couples with 19436 and 12050 materials, the Al_2O_3 coating showed the best properties under adhesive wear conditions; this material, mainly in combination with 19436 material, is suitable for friction nodes. The wear value is in accordance with the course of the friction coefficient of the investigated tribological couples. The wear value is connected with the surface hardness of materials in the friction couple. In soft materials - 12050 steel - intensive wear of the ceramic coating surfaces takes place, which is connected with an increase of the friction coefficient and the subsequent taking-up of particles from the coating surface. Under the adhesive wear conditions the ceramics-polyamide couple appears to be high-prospective, since it shows a low friction coefficient and minimum wear and seizure tendency.
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