Piston ring

Abstract

A piston ring is provided with a thermal spray coating that contains tungsten carbide and chrome carbide as a hard phase, and contains nickel as a metallic binder phase, and is characterized in that the thermal spray coating is formed by the spraying of a thermal spray powder that has been produced by means of a granulation sintering method, and that contains hard particles in which the mean particle diameter of the tungsten carbide has been adjusted by means of a BET method to fall within a range of not less than 0.15 μm and not more than 0.45 μm.

1 . A piston ring comprising:
 a thermal spray coating that contains tungsten carbide and chrome carbide as a hard phase, and contains nickel as a metallic binder phase, wherein   the thermal spray coating is formed by the spraying of a thermal spray powder that has been produced by means of a granulation sintering method, and that contains hard particles in which the mean particle diameter of the tungsten carbide has been adjusted by means of a BET method to fall within a range of not less than 0.15 μm and not more than 0.45 μm.   
     
     
         2 . The piston ring according to  claim 1 , wherein the thermal spray coating contains nickel within a range of not less than 7.0 wt % and not more than 18.5 wt % as a metallic binder phase. 
     
     
         3 . The piston ring according to  claim 1 , wherein the thermal spray coating has a composition that contains 7.0 wt % of nickel as the metallic binder phase, and 20 wt % of chromium carbide as the hard phase, and in which the remainder is made up of tungsten carbide as a hard phase and inevitable impurities. 
     
     
         4 . The piston ring according to  claim 2 , wherein the thermal spray coating has a composition that contains 7.0 wt % of nickel as the metallic binder phase, and 20 wt % of chromium carbide as the hard phase, and in which the remainder is made up of tungsten carbide as a hard phase and inevitable impurities. 
     
     
         5 . The piston ring according to  claim 1 , wherein the thermal spray coating has a composition that contains 12.5 wt % of nickel as the metallic binder phase, and 37.5 wt % of chromium carbide as the hard phase, and in which the remainder is made up of tungsten carbide as a hard phase and inevitable impurities. 
     
     
         6 . The piston ring according to  claim 2 , wherein the thermal spray coating has a composition that contains 12.5 wt % of nickel as the metallic binder phase, and 37.5 wt % of chromium carbide as the hard phase, and in which the remainder is made up of tungsten carbide as a hard phase and inevitable impurities. 
     
     
         7 . The piston ring according to  claim 1 , wherein a porosity of the thermal spray coating is 3% or less. 
     
     
         8 . The piston ring according to  claim 1 , wherein the thermal spray coating is formed by spraying using a high-speed frame spraying method.