Electrical Discharge Coating Method and Green Compact Electrode Used Therein

Abstract

An electrical discharge coating method comprising the steps of: generating pulsed discharge between a green compact electrode 3 and a treatment target surface 20 in a working fluid 10 ; thereby, depositing a component of the green compact electrode 3 onto the treatment target surface 20 so as to form a coating 21 , wherein the generating includes using the green compact electrode 3 which is formed through compression molding of metal powder having an oxide layer on each particle surface 20 thereof, as a main component thereof, the oxide layer being thicker than an oxide film normally obtained in air at normal temperature, whereby the metal component of the green compact electrode 3 is deposited onto the treatment target surface 20 so as to form the coating 21 containing the metal component as a main component thereof. It is possible to form a thick coating mainly containing a high hardness metal even on a low melting point metal such as an aluminum material, without depending on a carbide that reduces conductivity.

1 . An electrical discharge coating method comprising the steps of generating pulsed discharge between a green compact electrode and a treatment target surface in a working fluid; thereby, depositing a component of the green compact electrode onto the treatment target surface so as to form a coating,
 wherein the generating includes using the green compact electrode which is formed through compression molding of metal powder having an oxide layer on each particle surface thereof, as a main component thereof, the oxide layer being thicker than an oxide film normally obtained in air at normal temperature, whereby the metal component of the green compact electrode is deposited onto the treatment target surface so as to form the coating containing the metal component as a main component thereof.   
     
     
         2 . The electrical discharge coating method according to  claim 1 , wherein the metal powder is a powder of a metal selected from the group consisting of molybdenum, tungsten, chromium, molybdenum alloys, tungsten alloys, and chromium alloys. 
     
     
         3 . The electrical discharge coating method according to  claim 1 , wherein the metal powder is a mixed powder of two or more metals selected from the group consisting of molybdenum, tungsten, chromium, molybdenum alloys, tungsten alloys, and chromium alloys. 
     
     
         4 . The electrical discharge coating method according to any one of  claims 1  to  3 , wherein a percentage of the oxide layer of the metal powder is 5 to 11% by weight of the metal powder. 
     
     
         5 . The electrical discharge coating method according to any one of  claims 1  to  4 , wherein the treatment target surface is made of any material of aluminum, aluminum alloys, magnesium, magnesium alloys, titanium, and titanium alloys. 
     
     
         6 . A green compact electrode for an electrical discharge coating treatment, the treatment including generating pulsed discharge between the green compact electrode and a treatment target surface in a working fluid, and thereby a component of the green compact electrode is deposited onto the treatment target surface so as to form a coating,
 wherein the green compact electrode is formed through compression molding of metal powder, as a main component thereof, having an oxide layer on each particle surface thereof, the oxide layer being thicker than an oxide film normally obtained in air at normal temperature.   
     
     
         7 . The green compact electrode for an electrical discharge coating treatment according to  claim 6 , wherein the metal powder is a powder of a metal selected from the group consisting of molybdenum, tungsten, chromium, molybdenum alloys, tungsten alloys, and chromium alloys. 
     
     
         8 . The green compact electrode for an electrical discharge coating treatment according to  claim 6 , wherein the metal powder is a mixed powder of two or more metals selected from the group consisting of molybdenum, tungsten, chromium, molybdenum alloys, tungsten alloys, and chromium alloys. 
     
     
         9 . The green compact electrode for an electrical discharge coating treatment according to any one of  claims 6  to  8 , wherein a percentage of the oxide layer of the metal powder is 5 to 11% by weight of the metal powder. 
     
     
         10 . The green compact electrode for an electrical discharge coating treatment according to any one of  claims 6  to  9 , wherein the green compact electrode is formed through compression molding of the metal powder with a metal soap added thereto. 
     
     
         11 . The green compact electrode for an electrical discharge coating treatment according to any one of  claims 6  to  10 , wherein the green compact electrode is formed through compression molding of the metal powder with a metal powder added thereto, the added metal powder having a higher conductivity than that of the metal powder and not being subjected to an oxidation treatment. 
     
     
         12 . The green compact electrode for an electrical discharge coating treatment according to  claim 11 , wherein the higher-conductivity metal powder is any one of a copper powder and a silver powder. 
     
     
         13 . The green compact electrode according to any one of  claims 10  to  12 , wherein an amount of the metal soap added is 1 to 4% by weight of the metal powder. 
     
     
         14 . The green compact electrode according to any one of  claims 10  to  12 , wherein an amount of the higher-conductivity metal powder added is 2 to 4% by weight of the metal powder.