METHOD OF INCREASING THE WEAR RESISTANCE OF A NICKEL-GRAPHITE-BASED COMPOSITE PLASMA COATING BY ADDING COPPER ALLOYS

Background. The article considers the possibility of expanding the areas of application of plasma coatings based on the nickel-graphite system by adding lead-free copper alloys to the composition, which have an affinity for the nickel shell of the nickel-graphite powder and, in addition to preserving the tribotechnical properties of nickel-graphite, can provide the necessary level of cohesion of the coating. Objective . The aim of this work is to study the effect of the content of the copper alloy CuAl10Ni5Fe4 when added to nickel-graphite (NPG-75) on the tribotechnical characteristics of the composite plasma coating. Methods. As part of the work to determine the influence of the copper alloy content in nickel-graphite on the tribotechnical properties of the plasma composite coating, friction and wear tests were conducted on samples with 35, 50, 75 and 90 wt.% copper alloy CuAl10Ni5Fe4 in nickel-clad graphite NPG-75 (75 wt.% nickel). The double copper-zinc alloy CuZn10 was used as a standard. Results . It has been experimentally established that plasma coatings based on NPG-75 with the addition of 50 wt.% CuAl10Ni5Fe4 have wear resistance increased by 10 times compared to pure NPG-75 with a friction coefficient significantly lower (0.36) than the CuZn10 standard (0.52). The coating on the counterbody of DIN C45 (hardness 45-48 HRC) is the smallest among the friction pair that were investigated in this work. Reducing the copper alloy content to 35 wt.% is impractical, since this results in active wear of the coating material and its spreading onto the counter body. Further increase in the content of CuAl10Ni5Fe4 powder in the composition leads to the occurrence of setting in the contact zone, as evidenced by a sharp (10-fold) increase in the wear of the coating samples, an increase in the temperature in the contact zone, and a ~ 2-fold increase in the friction coefficient. Conclusions. The optimal content of CuAl10Ni5Fe4 in a plasma coating based on NPG-75 is about 50 wt.%. This material allows you to reduce the friction coefficient from 0.52 (CuZn10) to 0.36 when paired with steel DIN C45. The mass wear of the steel counterbody is also significantly reduced, probably due to a change in the wear mechanism from adhesive (seizing) to oxidative wear. This allows us to significantly expand the scope of application of the Ni-C + CuAl10Ni5Fe4 material in aviation and space technology