The present invention relates to a combination of slide members made of ferrous material and having excellent wear resistance.
In the case where two members come into slide contact with each other, slip wear must be taken into consideration. Slip wear would take various modes depending upon combination of materials of the respective slide members, a surface state, a wearing condition and the like, and it is generally classified into coagulative wear, grinding wear and corrosive wear depending upon the mechanism of generation of the wear.
Coagulative wear is the mode of wear occurring in the case where metals having no significant difference in mechanical properties (including identical materials) come into frictional contact with each other. In the event that solid surfaces themselves come into frictional contact with each other, real contact would occur only at projected portions occupying very small parts of the surfaces and since the pressure at those portions would become very high and a deformation would occur at the real contact portions, surface contaminations such as adsorped layers of gas molecules, oxide films and oil films at those portions would be removed and coagulation would occur between the respective solid surfaces. As a result, the material having weaker mechanical strength would be taken away from the slide surface layer.
Grinding wear would arise in the case hardness of one of the contact surfaces is considerably higher than that of the other contact surface, then projecting portions of the surface having the higher hardness are pressed into the softer material due to the contact pressure, hence the softer material would be scraped out as a result of slide movement, and abrasive powder would be produced.
The scuffing phenomena (the phenomena in which coagulation between frictional surfaces themselves is remarkable and mainly the material having weaker mechanical strength is taken away from the surface layer of the member of that material) which become an issue in relation to slide contact, for instance, between a cam shaft and a rocker arm, between a cylinder and a piston ring or the like in an internal combustion engine, are really the phenomena caused by coagulative wear, and the present invention is directed mainly to the technical problem of suppressing the scuffing phenomena.