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 we ar mechanism of oxide films on hot roll surfaces based on in-situ obse rvation of wear process. For this purpose, a CCD microscope tribosyste m, where ball on plate type wear apparatus was assembled, was newly de veloped and used. By using this system, dynamic wear processes of oxid e films on hot roll surfaces were observed successively. Based on such observations, wear modes of oxide films on hot roll surfaces were cla ssified into three types, such as ''ploughing or powder formation'', ' 'flake formation'' and ''spalling''. The conditions for the occurrence of all wear modes were summarized by a wear mode map which was newly introduced by using friction coefficient mu and dimensionless paramete r P-max/H-S(maximum contact pressure/Vickers hardness of substrate of hot roll). A wear controlling parameter S-w was introduced to estimat e specific wear rate of oxide films.