Preparation and Tribological Performance Testing of Bonded Solid Lubricating Coatings Used on Spherical Plain Bearings

Abstract

Abstract.To solve the lubricating problems of spherical plain bearings under high-low temperature, high vacuum, heavy loads and strong oxidation conditions, the PTFE and MoS2 based lubricating coatings were prepared on the inner rings of the spherical plain bearings by spraying technique. A self-made tribo-tester was used to investigate the friction coefficient, wear loss, and friction temperature increase of bearings with coatings under different oscillation frequencies. Using scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS), the worn surfaces of the coatings and the counter surfaces were characterized and analyzed. The results showed that PTFE and MoS2 based lubricating coatings significantly improved the tribological properties of the spherical plain bearings. The tribological performance of PTFE based coating was obviously superior to MoS2 based coating and its wear mechanism was adhesive wear. However, the MoS2 based coating mainly occurred severe adhesive wear and abrasive wear, and the tribological properties of spherical plain bearings with MoS2 coating were relatively optimal under low frequencies. This paper provides a reference to developing new lubricating techniques for the spherical plain bearings. IntroductionBonded solid lubrication coating is an effective solution to solve the lubrication and wear problems under harsh conditions of high-low temperature, high vacuum, heavy loads and strong oxidation conditions. Remarkable achievements have been made in many high technology fields [1-3]. Compared with thermal spraying [4][5], laser cladding [6], thin film deposition [7,8] and other technologies, the preparation process of adhesive solid lubricant coating is undoubtedly the most economical and feasible [9][10].Bonded solid lubrication coating is not only economical but also excellent in tribological properties. Currently, more than 95% of the lubricating materials achieve the lubrication performance through spraying technology to reduce the friction and wear [11]. Molybdenum disulfide (MoS2) has the six-party crystal structure formed by S-Mo-S covalent, which is similar to the "sandwich layer", and easily to slip and transfer into lubricant film on the contact surfaces [12] and its application in sliding contact surface can reduce the wear degree of the structure [13][14].However, pure MoS2 coatings in the wet air environment present is easy to be oxidized and leads to low hardness, resulting in poor wear resistance and limited application [15][16]. Polytetrafluoroethylene (PTFE) is widely used as a solid lubricant because of its excellent selflubricating property, low friction coefficient, thermal stability and chemical stability. But PTFE as wear-resistant materials can`t be used alone because of its low mechanical strength, poor wear resistance, and cold flow phenomenon [17][18][19]. The tribological performance of the organic solvent

Research on damage and failure behaviour of coated self-lubricating spherical plain bearings based on detection of friction torque and temperature rise

“…However, some researchers have begun to pay attention to these, and preliminary studies have been carried out. [15][16][17] The test standards used were still the standard for bearings with liners, and there were no clear judgements on the failure of bearings. In some studies on the failure of rolling bearings, torque has often been utilised to monitor the running state of the bearing.…”