Analysis of sliding wear mechanism of oxide films on hot roll surfaces based on in-situ observation of wear process by the CCD microscope tribosystem

The purpose of this investigation is to analyze microscopic sliding wear mechanism of oxide films on hot roll surfaces based on in-situ observation of wear process. For this purpose, a CCD microscope tribosystem, where ball-on-plate type wear apparatus was assembled, was newly developed and used. By using this system, dynamic wear processes of oxide films on hot roll surfaces were observed successively. Based on such observations, wear modes of oxide films on hot roll surfaces were classified into three types, such as "ploughing or powder formation, "flake formation" and "alling". The conditions for the occurrence of all wear modes were summarized by a wear mode map which was newly introduced by using friction coefficient μ and dimensionless parameter P_max/H_s (maximum contact pressure/Vickers hardness of substrate of hot roll). A wear controlling parameter S_w^* was introduced to estimate the specific wear rate of oxide films.