Efficiency of Antifriction Solid Lubricant Coatings for Metal–Polymer Friction Pairs

Tribotechnical testing results for antifriction solid lubricant coatings in a metal–polymer friction pair are presented. The testing has been carried out according to an ASTMG99 standard with the use of a friction machine operating according to a sphere–disk pattern at sliding velocity V = 0.8 m/s, load F = 23 N, and rotation frequency n = 310 min^–1. While testing, the value of sliding friction force was permanently registered, and the value of the friction coefficient was automatically calculated. Testing was carried out until preset friction path L = 2880 m accumulated. After testing a level of linear wear was measured for the spherical counterbody. Antifriction solid lubricant coatings based on molybdenum disulfide and polytetrafluoroethylene deposited onto steel samples were tested. Polyoxymethylene spheres 10 mm in diameter were used as a counterbody. The testing was performed with the use of different greases based on mineral and synthetic oils with a complex of antifriction additives. It is revealed that the use of antifriction solid lubricant coatings together with greases makes it possible to provide a 5.9 to 10.1-fold decrease in the linear wear of counterbodies, as well as a 1.5 to 2.3-fold decrease in the friction coefficient depending on the grade of the coating under application. By selecting an optimum combination of antifriction solid lubricant coatings and plastic grease one can achieve a decrease in the linear wear of the counterbodies amounting up to 14.2 times, and an approximately 4.4-fold decrease in the friction coefficient.