An Experimental Study of the “Hot-Spots” Occurring During the Oxidational Wear of Tool Steel on Sapphire

This paper describes some interesting preliminary results obtained with tool steel pins sliding against a rotating sapphire disk without lubrication. It is shown (i) that mild (oxidational) wear of the pin surface can be obtained with this combination of materials, (ii) that the “hot-spots” between the pin and the disk surfaces can be seen and photographed for size analysis, and (iii) that the temperature of the hot-spots can be estimated from the photographs. Some scanning electron micrographs were also taken of the pin surfaces at the end of the experiments, the objective being to complement the optical analyses, and thereby provide information about the number, size, and temperature of the hot-spots. The revelance of these estimates to the mechanisms involved in mild (oxidational) wear is also discussed.