Ropyak L. Scientific and technological bases of part manufacturing and product assembling, strengthened by plasma electrolytic oxidation of an aluminum layer

The object of research is the technological processes of manufacturing parts and assembly of products with the strengthening of working surfaces by micro-arc oxidation. The purpose of the work is to develop scientific and technological bases for the production of parts with the strengthening of their working surfaces by microdurgical oxidation of aluminum and assembly of products in order to increase the life of their work during operation in aggressive and abrasive environments. The actual scientific and technical problem of the mechanical engineering technology field was solved: the theoretical bases and technological means for oil and gas equipment resource increasing by the plasma electrolytic oxidation of an aluminum layer were developed. The ways of layered coating bearing capacity increasing, formed by the plasma electrolytic oxidation of an aluminum layer, were grounded. The schemes of layered coatings have been developed. The stress-strain state of a two-layer coating under for an arbitrarily oriented local load is studied. The method of rational design of a two-layer coating for local load is developed. The influence of the oxide layer thickness on the resistance of the ceramic-aluminum coating to inculcation is studied. A model of substrate reinforcement – an aluminum base with particles of aluminum oxide - is proposed. An estimation of the oxide coating bearing capacity reinforced layer thick-ness was carried out and the increase of the bearing capacity of the oxide coating was determined, as well as the robustness of the two-layer aluminum-aluminum oxide coating for bending with the twist of the cylindrical part was estimated. The group technological process of composite coating formation by a complex method with the use of plasma electrolytic oxidation of an aluminum layer has been developed. Studied material selection – aluminum alloys and steels and technologies of forming of blanks – is grounded. Strengthening technologies and equipment for plasma electrolytic oxidation of compact aluminum and aluminum coatings in electrolyte have been developed. An installation for spray coating of composite coatings by an arc method has been developed from the material of continuous wires and powders, which are introduced from the feeder. An installation for vibroelectric doping of the substrate before coating was modernized. Studying methods of coating properties, which allow to determine the level of residual stresses in coatings, to conduct electrochemical measurements and corrosion tests and tests on hydro- and gas-abrasive deterioration of parts with oxide coatings are developed. The plasma electrolytic oxidation technological parameter influence on the accuracy and quality of part surfaces is experimentally studied. The technological parameters of the plasma electrolytic oxidation process in the flowing electrolyte are optimized to ensure the quality of the surface and the accuracy of the shape of the cylindrical parts. The structure and phase composition of the oxide layer formed by the plasma electrolytic oxidation have been studied. Empirical dependencies were obtained for determining the surface roughness after diamond polishing of the oxide coating. The physical and mechanical properties of the oxide coating formed by the plasma electrolytic oxidation, the residual stresses in them, corrosion properties and wear resistance of the formed oxide layer are determined. Electrochemical method determines the level of admissive stresses in parts with coatings. The assembly of components from parts reinforced with the plasma electrolytic oxidation has been studied. The wheel assembling peculiarities of axial fans with clutch joints with a nut are studied. The method of designing a threaded connection with a collar nut is developed. The assembling stresses in the elements of the working wheel of the centrifugal fan – disk – conical shell have been studied. The design of the composite plunger of the pump is proposed: a steel shaft – a working cylinder, which strengthens the plasma electrolytic oxidation of the surface layer. The connection of the steel shaft to the working cylinder is carried out using a threaded connection with the adhesive layer. The method of calculating allowances for mechanical processing of parts with oxide coatings is developed. The cutting modes of round diamond grinding of the oxide coating layer are optimized. The bench testing of parts strengthened by the method of the plasma electrolytic oxidation: protective shaft of shafts of centrifugal pumps, piston rod piston pumps, two-way pumps, compressor pistons. The analysis of harmful factors that arise during the process of the plasma electrolytic oxidation is carried out and the scheme of purification, regeneration and recycling of spent electrolyte is proposed.