Application of the theory of mathematical planning when choosing the optimal modes of surface hardening

Abstract

The application of plasma coatings by the condensation of a substance under the conditions of ion bombardment opens up wide possibilities. The effect of nano-coatings on the properties of the material depends not only on the composition of the coating, but also on such parameters as the hardness of the base material, the purity of its surface and the thickness of the coating applied. The paper analyzes various models of the structure of the applied coatings. It has been established that the structure of the surface layers exerts a very strong influence on the process of friction and wear due to various mechanisms of energy relaxation. Chemical-thermal treatment is carried out in order to increase fatigue strength, hardness, corrosion resistance, wear resistance. One of the widely used methods of chemical-thermal treatment is cementation. Cementation is performed on steel with a carbon content of not more than 0.2%. When using a solid carburizer (it saturates the medium), heating is carried out in furnaces, when using a gas carburizer, in hermetic shaft furnaces. All methods of chemical-thermal treatment are laborious, differ in the duration of the processes, and the results do not always justify the costs. An analysis of the experience of a number of machine repair enterprises shows the effectiveness of using ion-plasma technologies. In order to obtain high wear and corrosion resistance, the formation of their stable characteristics, which contribute to increasing the durability of machine parts and mechanisms, it is necessary to determine the optimal coating conditions. In this regard, using the theory of experimental design, a study was made of the parameters of coating deposition and a relationship was established between the hardness of the substrate material, the surface roughness of the coating, the coating thickness and wear. As one of the indicators, hardness was chosen. It is easily verifiable anywhere in the product without compromising integrity, both before and after use. The practice of operating products made of steel with the application of plasma coatings on the working surfaces has shown that the surface roughness of the product on which the coating is applied should be at least 0.48 Ra. Otherwise, peeling of the coating is observed, which is applied due to poor adhesion of it and the substrate.

Keywords

• pads
• adhesion
• roughness
• wear resistance
• mathematical model