Hardness of a Metal Matrix Composite Coating Deposited by Plasma Spraying with a Dispersed Titanium Carbide Phase

The results of a study on the hardness of a composite coating formed by plasma spraying are presented. The economic feasibility and relevance of the research are analyzed in the context of the need for technologies to restore machinery in the agro-industrial sector by applying functional coatings to worn surfaces using plasma spraying. The objective of the study was to experimentally investigate the effect of plasma spraying parameters on the hardness of the resulting composite coating. A review of existing scientific works is provided, covering various aspects of coating hardness depending on the application methods and the use of multicomponent functional materials. The spraying was carried out using the UPNS-3040 unit. A powder mixture was selected for spraying, consisting of 76.5% PR-NKh17SR4 powder with a particle size of 40–64 µm and 23.5% titanium carbide powder with a particle size of 63–80 µm (average 73.6 µm). This mixture has proven effective in several of the authors’ previous studies in producing high-quality composite coatings. The resulting coating was tested for hardness in H_V (HRC) using a PMT-3 hardness tester under a load of 50 N. A correlation analysis of the data was carried out to identify multicollinear relationships between spraying parameters and coating hardness. A regression analysis was also performed, resulting in an equation describing the effect of plasma spraying parameters on the coating hardness. A graphical interpretation of the dependences was presented using desirability functions, which made it possible to assess the nature and degree of influence of spraying parameters on hardness values. The study showed that the hardness of the composite coating depends on three factors: arc current of the plasma torch, spraying distance, and mass feed rate of the sprayed material.