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The tribological properties of the surfaces of parts, namely their wear resistance and friction properties, are in many cases decisive for their proper function. To improve surface properties, it is possible to create hard, wear resistant coatings by thermal spray technologies. Using these versatile coatings it is possible to increase the lifetime, reliability and safety of parts. For proper function of the surface treatment it is necessary to find and keep the optimal condition and parameters during preparation, deposition and further processing of the sprayed part. The spraying angle is one of the deposition parameters that influence the quality of thermally sprayed coatings. According to the theory, with decreasing spraying angle the process deposition efficiency decreases, whereas the porosity of coatings increases, being a cause of aggravated microstructure and mechanical properties. In this paper, the microstructure together with the basic mechanical properties and wear of WC-Co and Cr3C2-NiCr HVOF sprayed coatings were investigated in dependence of the spraying angle. For each coating, the marginal spraying angle that can be used without a significant decrease of the coating’s quality was identified. With respect to the change in coating properties as well as to process deposition efficiency, the maximum 30° diversion from a normal spray direction is recommended in the case of WC-Co and 15° diversion in the case of Cr3C2-NiCr.

One of the tribological tests for the evaluation of friction properties is introduced in this paper. The test, named “Block-on-Ring”, is in accordance with the standard ASTM G-77 and in SKODA VÝZKUM Ltd. is realized on the VRS-3 renovated apparatus. The measurement is as follows: the flat surface of the sample is pressed against the cylindrical surface of a rotating wheel of the rotor material. Arbitrary oil is fed to the material contact surface and the increasing temperature is detected using a thermocouple. The friction force is recorded using the strain-gauge dynamometer. The test is performed in a number of periods and always after one expiration time the wear track formed in the sample is measured and evaluated. The final results are the summary of the partial results of the long-standing tests and are used for the preliminary detection of the friction behavior of individual material couples.