Estimation of the elasticity modulus of composite electroplated coatings during their layer-by-layer deposition

Introduction. To keep automobiles and tractors in operation conditions, it is necessary to restore the inner cylindrical surfaces of the friction pair parts. This is the most labor-intensive activity. The method of electroplated contact deposition of composite coatings, based on elastic plastic deformation of formed layers, is used for repairing surfaces. To use this method it is necessary to determine the values of the elasticity modulus, on which the wear resistance of tribocouplings depends. Materials and Methods. For the study, cylindrical samples made of 30 HGSA and 30 HGSNA steels were used. Electrolyte containing 200-250 g/l chromium oxide, 2.0-2.5 g/l sulfuric acid, and distilled water was used for electroplating the coatings. When calculating the stress-strain state, the apparatus of continuum mechanics was used. Results. The dependence of the coating pliability as a function of the parameters of individual elementary layers is determined. When the multilayer coating of three types (orthogonal-reinforced, cross-reinforced and quasi-isotropic) is applied, its structure does not depend on the angles of kinematic tool movement on the inner cylindrical surface of the part. For each type of coatings, the way to determine the constant stiffness coefficients of the layers is specified. The dependences for calculating the elasticity modulus of the applied material are derived from the values of the stiffness coefficients. Discussion and Conclusion. In determining the modulus of elasticity of multilayered composite coatings, the calculation is made for the individual layers by passing to the convective coordinates, which is in complete agreement with the Lagrange point of view on the study of the motion of a continuous medium. The results obtained are of practical significance in the selection of the coating material to be applied for the restoration of internal cylindrical surfaces.