MATHEMATICAL MODELING OF THE BEHAVIOR OF REFRACTORY PARTICLES OF A POWDER CORE IN A THERMAL DEFORMATION ZONE DURING SURFACING

Abstract

Restoration of the performance of parts and assemblies of equipment operating under conditions of abrasive wear can be achieved in two ways: by replacing worn parts with new ones or by building up layers of restoring and strengthening coatings on the worn surface to nominal dimensions. The first way is economically less profitable due to the fact that the cost of spare parts can reach up to 80 % of the initial cost of the equipment. The use of electrocontact surfacing with composite materials, in which a layer of the required thickness is applied to the worn surface, which has a predetermined level of operating characteristics, allows you to effectively solve the problem of extending the standard service life of technological equipment assemblies. The physical and mechanical properties of the coatings (bonding strength, wear resistance, hardness) depend on the behavior of refractory particles of the charge composition to the core in the cross section of the layer. Refractory particles are not deformed in the process of electrocontact deposition, coming into physical contact with the viscoplastic surface layers of the base metal of the parts under the action of the force on the roller-electrode. The specifics of the production of composite materials for electrocontact deposition of wear-resistant coatings determine the presence of crushed refractory particles of fragmentary shape in the deformation center, which can be oriented in different ways by their faces or edges relative to the surface of the part. The presented mathematical model considers the behavior of crushed refractory particles in the deformation center using the example of joint introduction of adjacent particles, presented in the form of idealized absolutely rigid wedges. The adequacy of the proposed model is confirmed by comparing the calculated data and the results of experimental studies. It has been established that the greatest depth of introduction is observed when introducing refractory particles in the form of a cone into the charge composition as a core as a wear-resistant component. Analysis of the obtained experimental data showed that the bond strength is significantly increased when refractory particles are introduced into the visco-plastic surface layers of the base metal of the part.