Mg or Mg-Alloy Housing and Method for Producing the Same

Abstract

A surface of a Mg or Mg-alloy housing of the present invention is subjected to wet blast using a mixture containing a chemical conversion treatment agent and an abrasive, whereby a chemical conversion film is formed on the surface of the Mg or Mg-alloy housing. Because of this, a chemical conversion film is formed simply on the surface of a molded product made of Mg or a Mg-alloy to reduce the correction by puttying, whereby a Mg or Mg-alloy housing is provided in which a decrease in yield and an increase in cost can be prevented.

1 . A method for producing a Mg or Mg-alloy housing, comprising:
 subjecting a surface of Mg or a Mg alloy to a wet blast treatment, using a mixture containing a chemical conversion treatment agent and an abrasive, thereby simultaneously forming unevenness due to the blast and a chemical conversion film on the surface of the Mg or Mg-alloy housing.   
     
     
         2 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein a surface roughness of the housing is in a range of 0.5 μm to 100 μm in terms of a 10-point average surface roughness. 
     
     
         3 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein the wet blast treatment includes injecting a mixture containing a liquid and an abrasive under a pressure in a range of 0.1 to 0.3 MPa. 
     
     
         4 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein the abrasive is at least one particulate material selected from the group consisting of alumina, zirconia, glass, and resin. 
     
     
         5 . The method for producing a Mg or Mg-alloy housing according to  claim 4 , wherein the resin is selected from the group consisting of melamine resin, urea resin, polyester resin, phenol resin, epoxy resin, and urethane resin. 
     
     
         6 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein an average particle diameter of the abrasive is in a range of 10 to 300 μm. 
     
     
         7 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein calcium used in a solution for the wet blast treatment is at least one selected from the group consisting of calcium nitrate, calcium nitrite, calcium thiosulfate, and tetracalcium phosphate. 
     
     
         8 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein manganese used in a solution for the wet blast treatment is at least one selected from the group consisting of manganese carbonate, manganese nitrate, manganese hydrogen phosphate, manganese biphosphate, and manganese fluoroborate. 
     
     
         9 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein phosphoric acid used in a solution for the wet blast treatment is at least one selected from the group consisting of orthophosphoric acid, condensed phosphoric acid, phosphorous acid, and hypophosphorous acid. 
     
     
         10 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein at least one selected from sodium chlorate and sodium hypochlorite is further added to a solution for the wet blast treatment as an oxidation accelerator. 
     
     
         11 . The method for producing a Mg or Mg-alloy housing according to  claim 10 , wherein an added amount of the oxidation accelerator is in a range of 0.02 to 2 g/L. 
     
     
         12 . The method for producing a Mg or Mg-alloy housing according to  claim 1 , wherein a proportion of the chemical conversion treatment agent of a solution for the wet blast treatment is 70 to 90% by mass, and a proportion of the abrasive of the solution for the wet blast treatment is 10 to 30% by mass.