鋳鉄における微視的及び巨視的焼付きメカニズムの研究

概要

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In this study, seizing was considered as the state when the sliding surface became severe wear according to Nakaharas model. The aim of this research was to evaluate the seizing of cast iron from the viewpoints of temperature rise, coefficient of friction, wear volume and surface state, under two different conditions, and the mechanism of seizing was discussed. Two kinds of seizing were observed, “macro-seizing” and “micro-seizing”. Moreover, a model of the seizing concerning micro and macro-seizing was proposed. When the disturbance like an abrupt increase in load is given in a stable sliding condition, the seizure occurs, followed by plastic flows and an increase in contact area. The contact pressure keeps lower than the critical pressure, the surface becomes smooth and stable sliding is recovered due to the formation of a surface film in the micro-seizing. It seems that the predominant film formed is of graphite at low velocity and oxide at high velocity for cast iron. When the contact pressure becomes greater than critical pressure, the macro-seizing occurs. The apparent critical pressure is 20 MPa at 4.8 m/s for cast iron.