The bolt tightening is a joining technique in which multiple clamped parts are connected by utilizing primarily frictional forces. Therefore, investigations regarding the coefficients of friction for various types of contact surfaces have been conducted. Because some bolted joints in machinery structures including vehicles are exposed to high temperatures during use, it is thought that it is important to understand the influences of temperature on the coefficients of friction. In this study, new equipment to measure these coefficients at high temperatures are developed, and the measurements are conducted for specimens with surface conditions similar to those of vehicle bolts treated as corrosion protection. The results of the coefficients of friction at different temperatures and the differences observed in the surfaces are shown.
Morozumi et al. (2025) studied this question.