Effect of Technological Plasma Spraying Conditions on the Sprayed Layer Thickness

Abstract—Parts of technological machines, complexes, and equipment used in many industries are subjected to various types of mechanical wear, which leads to a significant decrease in their durability and an increase in the maintenance and operation costs. We have identified promising areas for improving the technologies of plasma spraying of wear-resistant coatings. Special attention is paid to the functional layer thickness, since, it exerts a significant effect on the quality of coatings deposited by plasma spraying methods. The purpose of the work is to develop mathematical models to reveal the laws of influence of the technological plasma spraying parameters of wear-resistant coatings on the sprayed functional layer thickness. (Experimental) Grade 45 steel samples are used for experimental studies, and a nickel-based PG-SR4 (PR-NKh17SR4) powder is plasma-sprayed on them. The plasma generator arc current, the spraying distance, and the plasma-forming gas flow rate are used as the main technological plasma spraying parameters. The sprayed coating thickness is measured using standardized equipment. Statistical processing of the coating thicknesses values is carried out using a complete factorial experiment using the Box–Wilson method. (Results and discussion). An experimental mathematical model is developed to describe the plasma spraying of coatings, and its operability is demonstrated. The criteria used to estimate the variance of experiments and the adequacy and significance of the derived regression equations are described. The Statistica program is used to interpret the dependences under study graphically. (Conclusions) Mathematical planning of experiment is applied to develop models to find the relationship between the coating thickness and the specified technological plasma spraying parameters. The results of analysis of the presented analytical dependences show that the coating thickness is most strongly affected by the plasma generator arc current.