Modeling of Temperatures in the Conjunction of a Vapor-Lubricated Four-Ball Wear Tester

Abstract

Recent studies have shown that solid films formed from vapor-delivered lubricants can provide effective lubrication for load-bearing systems at elevated temperatures. A model is developed to describe the processes occurring in the conjunction between two load-bearing surfaces which are being lubricated by a film deposited from a vapor phase. This analysis combines models of the chemical kinetics of the deposition process and the wear process under ideal conditions in which all the wear is due to the reaction of the lubricant vapor with this surface material. The analysis is applied to the case of 1/2 in. M50 steel ball bearings being lubricated in a four-ball wear tester by a vapor at 370°C containing 0.5 mole percent tricresyl phosphate in a nitrogen carrier gas. Under conditions of 600 rpm and a 10 kg load, the analysis indicates that the temperature in the conjunction is 540°C. This analysis elucidates the coupled processes which take place during vapor-deposited lubrication at elevated temperatures.