Tribochemical degradation of vacuum‐stable lubricants: A comparative study between multialkylated cyclopentane and perfluoropolyether in a vacuum ball‐on‐disc and full‐bearing tests

Abstract

In this study, the decomposition of a multialkylated cyclopentane (MAC) and a perfluoro-poly-ether (PFPE) lubricant was investigated in a ball-on-disc sliding test under vacuum and in a rolling contact fatigue (RCF) test on full bearings. In situ mass spectrometry was conducted to study the tribochemical formation of hydrogen in a steel-on-steel ball-on-disc sliding contact. Further investigations on lubricant degradation in rolling-sliding contact indicated fragmentation and oxidation reaction of the MAC oil by interaction with the oxide layer and the nascent bearing steel. Finite element method (FEM) analysis was carried out to model the contact in the ball-on-disc experiments and to extract contact surface temperature fields. Post-RCF hydrogen analysis of bearing components indicated increased hydrogen content in the samples lubricated with the MAC fluid. The RCF tests with PFPE did not indicate any signs of surface damage. K E Y W O R D Sball-on-disc sliding test, cylindrical roller thrust bearings, hydrogen, lubricant degradation, lubrication, rolling contact fatigue, vacuum tribology

Practical Evaluation of Ionic Liquids for Application as Lubricants in Cleanrooms and under Vacuum Conditions

“…In addition, this product group often exhibits high starting friction, which is problematic for the safe design of the drive technology [11]. There is also a risk that the MAC oils generate hydrogen through tribochemical reactions, which can lead to premature rolling bearing failures [12,13].…”

Alkylated Polyphenyl Ethers as High-Performance Synthetic Lubricants

“…To minimize these costs, lubrication science has been focused on reducing friction, minimizing wear, evacuating heat, and removing contaminants. However, it is well known that lubricants can undergo thermal decomposition in response to the heat of friction or high operating temperatures, as well as tribochemical decomposition induced by the high activity of nascent steel surfaces [1][2][3][4][5]. It has been suggested that hydrogen generated by lubricant decomposition is also an important aspect of the hydrogen embrittlement of metal parts.…”

Polymer‐silica additive as a modifier of tribological properties of ecological grease, improvement of fatigue resistance

“…They showed that an increase in the concentration of such additives improves the anti‐wear and anti‐seizure properties; however, at the same time, it causes a deterioration of resistance to fatigue wear. A comparison of the decomposition of multialkylated cyclopentane and perfluoro‐poly‐ether greases as a result of friction was presented by the authors of the publication 23 . The results of rolling contact fatigue studies showed that hydrogen assisted damage in multi‐alkylated cyclopentane‐lubricated bearings, and the perfluoro‐poly‐ether lubricated bearing did not show any damage despite the longer test duration.…”