Lubrication Studies with Alumina‐on‐Alumina, Steel‐on‐Steel, and Steel‐on‐Alumina Bearing Systems

In metal bearing systems, good lubricants for boundary lubrication generally show chemical interaction with the bearing surface under the conditions of temperature and pressure generated in the sliding contact. In this study, tests in a four‐ball wear tester have been used to compare lubricants under similar loadings using steel‐on‐steel, steel‐on‐alumina, and alumina‐on‐alumina bearing systems. In general, the alumina appears to be far less reactive with lubricants than steel. Alumina‐on‐alumina bearing systems do show a sensitivity to lubricant chemical composition with generally higher wear values than the other two bearing systems. Steel‐on‐alumina bearing systems generally show better wear characteristics than the all‐alumina systems which indicates the improved chemical interactions between the steel and the lubricant. This study shows that the chemical reactivity of the lubricant with the bearing surface is important in the wear process.