Research of Thermal Coatings of Composite Materials

Abstract

This study was carried out in compliance with the State program of scientific research of the Republic of Belarus on the task “Formation of wear-resistant composite coatings with high-technology. Development of streams in the machine parts with high contact load”. The achieved level of physical, mechanical and performance properties of the thermal coatings developed compositions makes them suitable for hardening-restoring parts of friction pairs, working in conditions of fretting corrosion, a wide range of specific loads and sliding speeds. Based on the goal of the research, developed composite materials based on abrasion-resistant, anti-friction and thermo-reactive powders form composite anti-friction coating provide the required level of physic-mechanical properties and performance characteristics (wear resistance, porosity and bond strength). Applying nickel, iron, copper (bronze, Babbitt) as base materials helps to improve wear resistance, resistance to fretting corrosion, anti-friction properties and adhesion. The study of the structure determined that the structure of the resulting coatings matches with the Charpy rule; spraying particles are well plasticized substantially, not surrounded by oxide films. The coating has a low porosity (less than 5%); the individual phases micro-hardness is up to 10000 MPa and bases on 7500 MPa. Reduction of the quantities of residual stresses produced a heated base and spraying of the intermediate layer of thermo-reactive material NiAl. Study of residual stresses and their distribution across the thickness of the composition “cover, sub layer, the basis” made it possible to determine that the application of the selected sub layer and spraying modes combined with compositions developed can reduce the level of residual stress in the coating up to 3 times.