Electrolytic phosphating treatment method and warm or hot forging method

Abstract

The invention provides an electrolytic phosphating treatment method that forms a film by causing a large current to flow at a voltage as low as possible and can improve efficiency. Namely, the invention provides an electrolytic phosphating treatment method for forming a film containing a metal precipitating from a nitrate, and a phosphate, by executing electrolysis between a metal that is the same as a metal of a nitrate of a treatment bath as an electrode and a work by using a D.C. power source, the treatment bath comprising phosphoric acid, zinc, iron or manganese as a metal capable of dissociating phosphoric acid and dissolving in phosphoric acid, and a solution dissolving a nitrate of a metal to become a film component, wherein anions other than nitrate ions and metal ions other than the metal ions to become the film component are present at not greater than 0.5 g/L, the metal ion dissolving from the nitrate is present at greater than 10 g/L and phosphoric acid and phosphate ion are present at not greater than ½ of the metal ion dissolving from the nitrate.

1 . An electrolytic phosphating treatment method for forming a film, containing a metal precipitating from a nitrate and a phosphate by executing electrolysis of a metal that is the same as a metal of a nitrate of a treatment bath as an electrode and a work by using a D.C. power source, the treatment bath comprising phosphoric acid; zinc, iron or manganese as a metal capable of dissolving in a phosphoric acid solution and dissociating phosphoric acid; and a solution dissolving therein a nitrate of a metal to become a film component, wherein anions other than nitrate ions and metal ions other than the metal ions to become the film component are present at not greater than 0.5 g/L, the metal ion dissolving from the nitrate is present at greater than 10 g/L and phosphoric acid and phosphate ion are present at not greater than ½ of the metal ion dissolving from the nitrate.  
   
   
       2 . An electrolytic phosphating treatment method for forming a film containing a metal precipitating from a nitrate and a phosphate by executing electrolysis between a metal that is the same as a metal of a nitrate of a treatment bath as an electrode and a work by using a D.C. power source, the treatment bath comprising a phosphate solution prepared by dissolving zinc in a phosphoric acid solution; phosphoric acid and phosphate ions; zinc ions as a metal capable of dissociating, and dissolving in, phosphoric acid; and a solution dissolving a nitrate of nickel, cobalt, manganese, copper or zinc; wherein anions other than nitrate ions and phosphate ions and metal ions other than the metal ions to become the film component are not greater than 0.5 g/L, respectively, the metal ion dissolving from the nitrate is greater than 10 g/L and phosphoric acid and phosphate ion are not greater than ½ of the metal.  
   
   
       3 . The electrolytic phosphating treatment method according to  claim 1 , wherein the metal ions dissolved from the nitrate are present at at least 20 g/L and phosphoric acid and the phosphate ion are present at ½ of the amount of the metal ions dissolved from the nitrate.  
   
   
       4 . The electrolytic phosphating treatment method according to  claim 1 , wherein an oxidation reduction potential (ORP: hydrogen standard electrode potential) of the phosphating treatment bath is at least 770 mV.  
   
   
       5 . The electrolytic phosphating treatment method according to  claim 1 , wherein an electrolytic voltage is 6 V or below and an electrolytic current is at least 2 A/dm 2 .  
   
   
       6 . The electrolytic phosphating treatment method according to  claim 1 , wherein an electrolytic voltage is 15 V or below and an electrolytic current is at least 20 A/dm 2 .  
   
   
       7 . A lubrication treatment method for warm or hot forging of a metal, characterized by using a work, the work having a film having a lubrication function and being formed by the steps of: 
 forming a formation film formed of a phosphate plus a metal constituted by a metal having a melting point higher than the temperature applied to the work during warm or hot forging of a metal and a phosphate on a surface of the work; and    supporting a lubricant on the formation film.    
   
   
       8 . The lubrication treatment method for warm or hot forging, wherein a phosphating treatment film to be formed on a surface of a work and constituted by a phosphate plus a metal is a phosphating treatment film according to  claim 1 .  
   
   
       9 . The lubrication treatment method for warm or hot forging according to  claim 7 , wherein the lubricant is an organic compound containing an organic fatty acid salt or an inorganic high molecular weight compound having a multi-layered structure.  
   
   
       10 . The lubrication treatment method for warm or hot forging according to  claim 9 , wherein the lubricant is a stearate, a graphite, molybdenum sulfide or a mica.  
   
   
       11 . A warm or hot forging method comprising the steps of: 
 forming a phosphate+metal film constituted by a metal having a melting point not lower than a temperature applied to a work during warm or hot forging of a metal and a phosphate;    supporting a lubricant on the film to form the work having the film having a lubrication function in warm or hot forging; and    conducting warm or hot forging.    
   
   
       12 . The warm or hot forging method according to  claim 11 , wherein the phosphate+metal film contains a phosphate that does not contain water of crystallization by differential thermal analysis.