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When a complex geometry is rotated in front of the thermal spray gun, the following kinematic parameters vary in a coupled fashion dictated by the geometry: Stand-off distance, spray angle and gun traverse speed. These fluctuations affect the conditions of particle impact with major implications on the coating’s properties. This work aims to probe into the interplay and isolated effect of these parameters on vital coating characteristics in applications requiring variable stand-off distance and spray angles. WC-17Co powders are sprayed via HVOF on steel substrates in a set of experiments that simulates the spray process of a non-circular cross section, while it allows for individual control of the kinematic parameters. Comprehensive investigation of their influence is made on deposition rate, residual stresses, porosity and microhardness of the final coating. It was determined that oblique spray angles and long stand-off distances compromise the coating properties but in some cases, the interplay of the kinematic parameters produced non-linear behaviours. Microhardness is related negatively with oblique spray angles at short distances while a positive correlation emerges as the stand-off distance is increased. Porosity and residual stresses are sensitive to the spray angle only in relatively short stand-off distances

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The state of particle impact (velocity and temperature) significantly affects the coating's microstructural, mechanical properties and wear performance. The spray stand-off distance and spray angle dictate particle velocity components and temperature at impact. This work aims in advancing the understanding of their effect and interplay in regard to the sliding wear performance as well as the mechanisms of wear themselves of HVOF-sprayed WC-17Co coatings. Dry sliding wear resistance was evaluated by a pin-on-disk test, and significant interplay between the spray parameters was observed. A large number of experiments in a full-factorial manner provided insights into the progressive tribofilm build-up and wear damage modes and allowed for proposing mechanisms regarding their occurrence. Small deviations from the normal spray angle at long stand-off distances proved to be beneficial for the wear performance of the coatings. The highest friction coefficient and most aggressive wear damage were observed in coatings with a rich coverage of the wear track with a tribofilm. The phase composition of the coatings proved to be the principal contributor in the wear performance.