Electrophoretic deposition

Abstract

In electrophoretic deposition of a ceramic, the anode is or incorporates a metal which is the same as the metal in the metal salt dissolved in the solvent. Preferably the salt is magnesium nitrate.

1 . A method for the electrophoretic deposition of a ceramic which method comprises passing an electric current through a liquid in which is suspended the ceramic, in which method the liquid comprises a solvent in which is dissolved a metal salt and the anode incorporates an anodic metal which is the same as the metal in the metal salt.  
     
     
         2 . A method as claimed in  claim 1  in which the anodic metal is magnesium or aluminium.  
     
     
         3 . A method as claimed in  claim 2  in which the metal salt is a nitrate.  
     
     
         4 . A method as claimed in any one of  claims 1  to  3  in which the anode is formed of the anodic metal or an alloy of the anodic metal  
     
     
         5 . A method as claimed in any one of  claims 1  to  3  in which the anode is formed of a support metal with a higher electrical potential than anodic metal on which there is a layer or strip of the anodic metal at least partially covering the anode.  
     
     
         6 . A method as claimed in any one of  claims 1  to  4  in which the solvent is isopropanol, the salt is magnesium nitrate and the anode incorporates metallic magnesium.  
     
     
         7 . A method as claimed in any one of the preceding claims in which the liquid incorporates a compound which can liberate oxygen.  
     
     
         8 . A method as claimed in 7 in which the compound is hydrogen peroxide  
     
     
         9  A method as claimed in any one of  claims 1  to  6  in which oxygen or air is bubbled through the solvent in the vicinity of the cathode.  
     
     
         10 . A method as claimed in any one of the preceding claims in which the ceramic is a phosphor.  
     
     
         11 . A method as claimed in  claim 10  in which the ceramic is a copper doped zinc sulphide phosphor and the anode incorporates copper.