DETERMINATION OF INFLUENCE OF ANTI-FRICTION COMPONENTS ON THE TRIBOLOGICAL PROPERTIES OF THREAD COATINGS

Within the development of a material, which forms a multifunctional coating on the threaded surface of tubes and joints, the authors identified the requirements specified for a coating. One of the main requirements is the possibility to perform the repetitive screwing of threaded connections without thread damage. The necessity to obtain a high level of anti-friction properties of a coating aroused the study of the influence of anti-friction additives of various effect on the tribological properties of a coating: the decrease in the friction coefficient of conjugate surfaces and ensuring the abrasion resistance of a coating. To identify the influence of anti-friction additives of various effects on the functional properties of a coating, the authors carried out the comparative laboratory tests of thread coatings containing various anti-friction additives under the sliding friction at the reciprocation according to the “fixed plate - finger” scheme. As the anti-friction components, the authors used graphite, molybdenum disulfide, and polytetrafluoroethylene (PTFE), which have different anti-friction properties. The tests were carried out for the coatings containing the complex of additives as well: graphite - PTFE, molybdenum disulfide - PTFE. The authors evaluated the tribological properties of the resulting coatings according to their friction coefficient value and abrasion resistance. To select optimum concentrations of anti-friction components, the authors tested the materials containing the complex of additives with different concentrations of graphite and molybdenum disulfide. To confirm the results of laboratory tests, the authors carried out full-scale tests in the factory environment when applying the selected coating to the threaded surface of a tube and a joint. The research identified the positive effect of the multipurpose utilization of anti-friction components. The authors determined the systems of anti-friction components (graphite - PTFE and molybdenum disulfide - PTFE) and their optimum concentrations (graphite and molybdenum disulfide - 8 wt. %, PTFE - 6 wt. %) in the thread coating material. The full-scale tests in the factory environment confirmed the results of laboratory tests.

thread lubricating coating, tribological properties, anti-friction components, friction coefficient, abrasion resistance