Modernization of friction unit of a KT-2 tribometer for evaluation of the friction properties of thin coatings upon friction in boundary lubrication conditions

Abstract

The results of studying the tribological characteristics of thin coatings of steel parts on a modernized friction unit of a KT-2 machine in the boundary lubrication mode are presented. To provide high accuracy and reproducibility of the results standard elements of rolling bearings — balls and rollers, which are characterized by the uniformity of the structure and composition, as well as high quality of the surface treatment are used as samples. The developed design of the mandrel ensured friction contact of the ball mounted on the machine spindle with the ends of three rollers mounted with high accuracy at an angle of 35°30’ to spindle axis of the installation to ensure the same distribution of the axial load between three rollers like in the case of the four-ball contact between three lower balls. The coatings under study were applied to the flat ends of the rollers, which is much easier than their application to cylindrical or spherical surfaces. A standard ball made of steel ShKh-15 or wear-resistant ceramics served as a counterbody. The modernized unit is recommended to be used on traditional four-ball machines for laboratory assessment of the effect of thin wear-resistant coatings on the antifriction properties of lubricants.