On the Mechanism of Boundary Lubrication. II. Wear Prevention by Addition Agents

O. Beeck, J. W. Givens, E. C. Williams
1940 Proceedings of the Royal Society A  
P lates 5, 6] I f two m etal surfaces slide over each oth er in th e presence of a lu b rican t an d u nder high load, high pressures an d tem p eratu res prevail a t those isolated spots w hich actu ally carry th e load, leading to w ear and possibly to breakdow n. The action of w ear p reventing agents und er these conditions has been studied in detail an d it has been found th a t such agents are effective th ro u g h th eir chem ical polishing action, by which th e load becomes d istrib u
more » ... ecomes d istrib u ted over a larger surface an d local pressures and tem peratures are decreased. Especially effective are com pounds containing phosphorus or o ther elem ents of group V of th e periodic system . These have been found to form a m etal phosphide or homolog on th e surface which is able to alloy w ith th e m etal surface, lowering its m elting p o in t m arkedly, and by th is action aiding g reatly in m aintaining a polish. The w ear experim ents were carried o u t w ith a highly sensitive and accurate m eth o d w hich uses m etal-p lated steel balls as its sliding elem ents. U nd er th e experim ental conditions additions of T5 % triphenyl phosphine or triphenyl arsine in w hite oil gave w ear prevention factors of 7-2 and 12-2 respectively (relative to pure w hite oil). A fu rth er addition of 1 % of a long chain po lar com pound is able to double th e w ear prevention factor obtained w ith th e polishing agents and wear prevention factors as high as 17-6 have been observed. The specifically physical action of th e long-chain polar com pounds is discussed in th e preceding paper. On th e m ech an ism o f b o u n d a ry lu b ric a tio n 1. I n t r o d u c t io n Engineering developments of the last ten years have called for lubrica tion under more and more severe conditions both with respect to tempera ture and pressure. These demands have been met, up to the present, by the purely empirical method of adding small amounts of certain chemicals to the oil in order to impart certain desired properties. One of the most im portant of these properties is the prevention of wear and in extreme cases of seizure and breakdown. Excessive wear, if truly mechanical, will in all cases eventually lead to seizure unless the welding of the surfaces is prevented by anti-welding agents, which of necessity are corrosive in order to create non-metallic bodies between the surfaces. Such remedy will prevent [ 103 ]
doi:10.1098/rspa.1940.0113 fatcat:4duyizofrff5rpzuprtd55sznu