Protection of mining equipment parts operating in underground mining conditions from biocorrosion

Introduction. Biological corrosion of mining equipment parts is an important problem. Ti-Cu-based coatings provide effective protection against such corrosion. A significant number of mining equipment parts operate under conditions of intense wear. These are parts such as pins, rollers, gears, racks, drive stars, etc. When applying a coating to such parts, it is important not only to increase the anti-corrosion properties, but also to maintain or improve the tribological properties of the parts being processed. The use of coatings based on metal oxides is an effective tool to combat bio corrosion. Among such metal oxides, nanocomposites that include a combination of TiO2 and Cu2O have performed best. These composites have a narrow bandgap, chemical stability and low toxicity. However, the issue of their influence on the tribological properties of parts remains incompletely studied. The purpose of this work is to analyze the structural features, mechanical properties and wear resistance of the Ti-TiO2-Cu-Cu2O coating applied by detonation spraying. Materials and methods. In this work, Ti-TiO2-Cu-Cu2O composite coatings were formed on a steel substrate. Sputtering was carried out using a multi-chamber detonation accelerator system. The coating process was carried out layer by layer using a device that moved back and forth with a lateral displacement. Titanium (PTN-8VT10) and copper (PMS-1) powders were used as raw materials. Wear tests were carried out using a disk-pin design. X-ray structural analysis was carried out for the obtained samples, and the microstructure of the coatings was studied. The micro hardness of the applied coating was also determined. Results. In the resulting coatings between the two elements Ti and Cu of the deposited powders, no chemical reaction or intermetallic compounds were detected. Ti-TiO2-Cu-Cu2O composite coatings mainly consisted of TiO2 and Cu2O, with titanium and copper acting as a binder, providing a high density of the composite material. Distinct formations of metallic Ti and Cu particles are observed in various regions of the microstructure, with many formations of metallic Ti retaining their spherical shape. The Ti-TiO2-Cu-Cu2O coating has a high average hardness of 640 HV0.2. The coefficient of friction when the Al2O3 counter body slides over the coating after a short running-in cycle did not change and amounted to 0.38. Discussion. The analysis of the cross section revealed that the coating material has a dense structure, characterized by strong inter lamellar-type connections, and has no signs of destruction or cracks. The absence of cracks and delamination along the boundary between the substrate and the coating indicates the high quality of adhesion to the base. The thickness of this composite coating is approximately 340 ± 20 micrometers. The increased hardness of this coating can be explained by the partial melting and rapid solidification of powder particles during spraying, as well as its lamella-type compositional structure. The micro hardness profile inside the Ti-TiO2-Cu-Cu2O coating remains uniform. During tribo-technical tests with a 100Cr6 counter body, the friction coefficient of the tribo couple after running-in decreased as the sliding cycles increased. This effect is due to the formation of a tribo layer on the worn surface of the coating, which serves as protection against severe wear. These conditions prevent the counter body from sticking to the coating surface, which reduces the likelihood of adhesive wear. The main composition of the sealing tribo layer is iron oxide, formed as a result of an increase in temperature on the sliding surface and wear of the steel counter body during dry sliding, which prevents adhesion in contact. Conclusions. The authors conclude that during the spraying of a Ti-Cu powder mixture, ceramic reinforcement is formed, where titanium and copper, interacting with atmospheric components at the time of spraying, are capable of forming new oxide phases. Due to the absorption of oxygen by titanium and copper during the deposition process, the resulting composite acquires an average micro hardness of 640 HV0.2. The analysis of the cross-section of the coating revealed that the coating has a thickness of about 300 microns, has a dense structure characterized by strong interlamellar-type connections, and has no signs of destruction or cracks. Resume. The results obtained show that Ti-TiO2-Cu-Cu2O coatings applied to critical parts of mining equipment not only protect them from bio-corrosion, but also increase tribological properties. This allows you to increase the maintenance-free service life of equipment in mining operations. Suggestions for practical applications and future research directions. Ti-Cu composite coatings obtained by detonation thermal spraying can be used for such parts of mining equipment as pins, rollers, gears, racks, drive stars, etc. These coatings can be used not only to protect mechanisms and structural elements in mining conditions, but also for equipment elements operating in humid climates.