Coating for making electrical contact

Abstract

A surface treatment of electrical contact pieces in electrolytic plants, in particular of machines for the treatment of circuit boards and conductor sheets is discloses, wherein the contact pieces are made of titanium or some other oxidizing and therefore chemically and electrochemically resistant material. To eliminate unwanted metallization of the contact pieces as a result of an inadequate demetallization on account of the insulating oxide layer and in order to enhance protection against wear, an electrically conductive diamond coating is applied at least on the contact-making areas of the contact pieces.

1 . An electrically conductive diamond coating for use as protective surface layer on an electrical contact piece made of a chemically and electrochemically resistant metal which has an electrically insulating oxide layer at anodic polarity and is adapted to operate for electric current transfer to an item to be plated in an electrolytic machine. 
     
     
         2 . A device for electric current transfer to an item to be plated in an electrolytic machine, said device comprising:
 a contact piece which is made of a chemically and electrochemically resistant metal having an electrically insulating oxide layer at anodic polarity, said contact piece having a first surface which is intended for contact with the item to be plated; and   an electrically conductive diamond coating for application on the first surface of the contact piece.   
     
     
         3 . The device of  claim 2 , wherein the contact piece has a second surface which is coated with an electrically insulating layer and has no contact with the item, said second surface being exposed to an electrical field in an electrolytic cell of an electrolytic machine. 
     
     
         4 . The device of  claim 3 , wherein the contact piece is an exchangeable clamp jaw which is coated with the diamond coating, and further comprising a clamp which is provided with an electrically insulating coating. 
     
     
         5 . The device of  claim 2 , wherein the diamond coating has a thickness of approximately 1 to 10 micrometers. 
     
     
         6 . The device of  claim 2 , wherein the diamond coating has a thickness of approximately 2 to 5 micrometers. 
     
     
         7 . The device of  claim 2 , wherein the diamond coating has an electrical conductivity of up to 100 (Ωcm) −1 .