Experimental Investigation of Lubrication Properties at High Contact Pressure

Abstract

A new test rig with an ability to obtain clear interference images at high pressure contacts has been developed. The technique of relative optical interference intensity has been used to obtain film thickness profiles and then lubrication properties of some base oils including six kinds of polyalphaolefin and four kinds of silicone oil have been studied at different pressures ranging from 1 to 3 GPa. The results show that viscosities of these lubricants have notable effect on slopes of film thickness curves (speed versus film thickness in log–log form), and the observed phenomenon is attributed to fluidity and molecular structure. A comparison of experimental central film thicknesses with computational work shows that at high loads the relationship between load and film thickness usually go against prediction given by Hamrock and Dowson. In addition, when more pressure is applied, the profiles of film thickness become more and more flat while rolling speed do little to change the shape of profiles.