Sliding member

Abstract

The present invention provides a sliding member, of which the surface cavities do not disappear even after progress of wear of the sliding surface, which permits maintenance of a satisfactory seizure resistance, and has better seizure resistance, wear resistance and strength properties than in a sliding member having a porous chrome plating layer formed thereon in the conventional art. The sliding member of the invention has a laminated hard Cr plating layer comprising a plurality of hard Cr plating layers laminated on the sliding surface. Micro-cracks are formed on each hard Cr plating layer surface, and the micro-cracks of each hard Cr plating layer form micro-pores independent in the film-forming direction. On the cross-section of the laminated hard Cr plating layer, the porosity should be within a range of from 0.5 to 4.5%.

1 . A sliding member having a laminated hard Cr plating layer comprising a plurality of hard Cr plating layers laminated on a sliding surface, micro-cracks being formed on the surface of each hard Cr plating layer, the micro-cracks of each hard Cr plating layer forming independent micro-pores in the film forming direction; wherein porosity on a cross-section of said laminated hard Cr plating layer is within a range of from 0.5 to 4.5%.  
     
     
         2 . A sliding member according to  claim 1 , wherein porosity on the surface of said hard Cr plating layer is within a range of from 0.5 to 30%, and the number of micro-cracks on said surface is within a range of from 50 to 1,200 cracks/10 mm.  
     
     
         3 . A sliding member according to  claim 1  or  2 , wherein the thickness per layer of said hard Cr plating layer is within a range of from 0.1 to 60 μm.  
     
     
         4 . A sliding member having a laminated hard Cr plating layer comprising a plurality of hard Cr plating layers laminated on a sliding surface, micro-cracks being formed on the surface of each hard Cr plating layer, the micro-cracks of each hard Cr plating layer forming independent micro-pores in the film forming direction; wherein porosity on the surface of said hard Cr plating layer is within a range of from 0.5 to 5.0%, and the number of micro-cracks on said surface is within a range of from 50 to 1,200 cracks/10 mm.  
     
     
         5 . A sliding member according to  claim 4 , wherein the thickness per layer of said hard Cr plating layer is within a range of from 0.1 to 60 μm.