Coating structure, impeller, compressor, metal part manufacturing method, impeller manufacturing method, and compressor manufacturing method

Abstract

Said coating structure is provided with: a chemical conversion layer ( 11 ), which is formed by chemical conversion coating so as to cover the surface of an impeller body ( 10 ) obtained from a magnesium alloy that contains magnesium as the main component and which has a film thickness within a previously determined range; and a plating layer ( 12 ) formed so as to cover the chemical conversion layer ( 11 ).

1 - 8 . (canceled) 
     
     
         9 . A coating structure comprising:
 a chemical conversion layer that contains magnesium as a main component and is made of a phosphate-coated film and is formed in a manner of covering a surface of a base material which is made of a magnesium alloy containing at least one kind of element selected from a group consisting of gadolinium, terbium, thulium, and lutetium; and   a plating layer that is made of a nickel-based alloy and is formed in a manner of covering the chemical conversion layer.   
     
     
         10 . The coating structure according to  claim 9 ,
 wherein the plating layer is formed of a nickel-phosphorous alloy.   
     
     
         11 . The coating structure according to  claim 9 ,
 wherein the base material contains a atom percent of zinc, contains b atom percent of at least one kind of element, in total, selected from a group consisting of gadolinium, terbium, thulium, and lutetium, has a remaining portion made of magnesium, and has the factors a and b satisfying the following expressions (1) to (3), and   wherein the base material has at least one kind of precipitate selected from a precipitate group consisting of a compound of magnesium and a rare earth element, a compound of magnesium and zinc, a compound of zinc and a rare earth element, and a compound of magnesium, zinc, and a rare earth element.
   0.2≤ a≤ 5.0  (1)
 
   0.5≤ b≤ 5.0  (2)
 
   0.5 a− 0.5≤ b   (3)
 
   
     
     
         12 . An impeller comprising:
 the coating structure according to  claim 9 .   
     
     
         13 . A compressor comprising:
 the impeller according to  claim 12 .   
     
     
         14 . A metal part manufacturing method comprising:
 a step of forming a chemical conversion layer by performing chemical conversion treatment in a manner of covering a surface of a base material which is made of a magnesium alloy containing magnesium as a main component; and   a step of forming a plating layer which is made of a nickel-based alloy in a manner of covering the chemical conversion layer.   
     
     
         15 . An impeller manufacturing method comprising:
 the metal part manufacturing method according to  claim 14 .   
     
     
         16 . A compressor manufacturing method comprising:
 the impeller manufacturing method according to  claim 15 .   
     
     
         17 . The coating structure according to  claim 10 ,
 wherein the base material contains a atom percent of zinc, contains b atom percent of at least one kind of element, in total, selected from a group consisting of gadolinium, terbium, thulium, and lutetium, has a remaining portion made of magnesium, and has the factors a and b satisfying the following expressions (1) to (3), and   wherein the base material has at least one kind of precipitate selected from a precipitate group consisting of a compound of magnesium and a rare earth element, a compound of magnesium and zinc, a compound of zinc and a rare earth element, and a compound of magnesium, zinc, and a rare earth element.
   0.2≤ a≤ 5.0  (1)
 
   0.5≤ b≤ 5.0  (2)
 
   0.5 a− 0.5≤ b   (3)
 
   
     
     
         18 . An impeller comprising:
 the coating structure according to  claim 10 .   
     
     
         19 . An impeller comprising:
 the coating structure according to  claim 11 .