Engine Part

Abstract

An engine part according to the present invention includes: a metal substrate; a chromium plating layer covering at least a portion of a surface of the metal substrate, the chromium plating layer being formed from a trivalent chromium plating solution. The chromium plating layer includes a boron content of no less than 0.05 mass % and no more than 0.3 mass %, and the chromium plating layer has a thickness or 0.7 μm or less.

1 : An engine part comprising: a metal substrate; a chromium plating layer covering at least a portion of a surface of the metal substrate, the chromium plating layer being formed from a trivalent chromium plating solution, wherein,
 the chromium plating layer includes a boron content of no less than 0.05 mass % and no more than 0.3 mass %, and the chromium plating layer has a thickness or 0.7 μm or less.   
     
     
         2 : The engine part of  claim 1 , wherein the boron content in the chromium plating layer is no less than 0.05 mass % and no more than 0.1 mass %. 
     
     
         3 : The engine part of  claim 2 , wherein the chromium plating layer includes an iron content of 2 mass % or less. 
     
     
         4 : The engine part of  claim 3 , wherein the chromium plating layer covers a region of the metal substrate surface that is heated to a temperature of 350° C. or more. 
     
     
         5 : The engine part of  claim 4 , further comprising an underlying plating layer provided between the metal substrate surface and the chromium plating layer, wherein, the chromium plating layer has a thickness of no less than 0.2 μm and no more than 0.7 μm in the region that is heated to a temperature of 350° C. or more. 
     
     
         6 : The engine part of  claim 5 , wherein the underlying plating layer includes at least one of C and S. 
     
     
         7 : The engine part of  claim 6 , wherein the underlying plating layer further includes Ni. 
     
     
         8 : The engine part of  claim 5 , wherein the underlying plating layer is formed of a metal having a hardness lower than that of the Cr composing the chromium plating layer. 
     
     
         9 : The engine part of  claim 5 , wherein the underlying plating layer is formed from Ni plating. 
     
     
         10 : The engine part of  claim 3 , wherein the chromium plating layer has a color tone such that an L* value measured according to CIE (Commission Internationale de l'Eclairage) 1976 is in a range of no less than 68 and no more than 80. 
     
     
         11 : The engine part of  claim 5 , wherein the metal substrate is composed of a material containing Fe, Al, Zn, or Mg as a main component. 
     
     
         12 : The engine part of  claim 1 , wherein the metal substrate is a metal tube defining a passage through which an exhaust gas from an engine travels. 
     
     
         13 : An engine comprising the engine part of  claim 1 . 
     
     
         14 : A transportation apparatus comprising the engine part of  claim 12 . 
     
     
         15 : A transportation apparatus comprising the engine of  claim 13 .