EHL OF COATED SURFACES - .1. NEWTONIAN RESULTS

A complete solution for the Newtonian elastohydrodynamic lubrication of coated surfaces in line contact is introduced in this paper. The formulation is based mainly on solving the Reynolds equation coupled with the elasticity equations of the multilayered elastic halfspace. The effects of pressure inside the lubricated conjunction on the lubricant viscosity and density are considered. The mathematical model for this problem is a nonlinear one, and an iterative Newton-Raphson scheme is used for numerical solutions. The effects of coating material and coating thickness on the pressure profiles and the film shapes are presented. Two different coating materials (molybdenum disulfide as a soft coating and titanium nitride as a hard coating) are considered. The results show that the pressure spike is higher for hard coatings than for uncoated surfaces but that the pressure spike disappears for soft coatings. Furthermore, the coating thickness has a significant influence on the minimum film thickness and the maximum contact pressure for both soft and hard coatings.