microporous layer for lowering friction in metal-forming processes

Abstract

The invention is a microporous layer to be used in metal forming processes providing lower friction and improved resistance against galling. The layer is a thin, porous metallic film, which is electrochemically deposited on a metallic substrate, whereafter one of the metals of the deposited film is selectively removed by chemical etching, thereby leaving a micro- or even nanoporous layer on the surface of the substrate, which enhances lubricant entrapment leading to improved lubrication during metal forming processes.

1 . A process for producing a microporous layer for lowering friction in metal forming processes on a metal substrate, said layer being
 a thin metallic film, which has been electrochemically deposited on the surface of a metal substrate, and   capable of capturing a lubricant film in its pores,   
     wherein the following steps are carried out:
 (1) selecting one or more alloys, each consisting of two or more phases capable of providing a thin metallic film consisting of a mixture of fine grains rather than a solid solution, 
 (2) electrochemically depositing the alloy(s) on the metallic substrate, and 
 (3) selectively removing one of the metals or phases by chemical or electrochemical etching, 
 
     leaving a microporous layer on the substrate surface and thereby providing an ideal surface for said metal forming. 
   
   
       2 . The process according to  claim 1 , wherein the electrochemically deposited alloy is selected among FeIn, SnZn, AgCo, AgBi, AgFe, AgNi, InZn, BiCo, BiCu, BiSn, BiZn, PdCu, PdCo, CoCu, AgCu, AuCu and AuCo. 
   
   
       3 . The process according to  claim 2 , wherein the electrochemically deposited alloy is SnZn. 
   
   
       4 . The process according to  claim 1 , wherein the chemical or electrochemical etching is carried out by means of a solution dissolving a selected metallic phase, said solution being a concentrated or diluted inorganic acid, organic acid, inorganic base, organic base or mixtures thereof. 
   
   
       5 . The process according to  claim 1 , wherein the chemical etching of the Zn phase is carried out with diluted hydrochloric acid. 
   
   
       6 . The use of a microporous layer produced by the process according to  claim 1  as a lubrication carrier for cold forming of metals. 
   
   
       7 . The use of a microporous layer according to  claim 6  as a lubrication carrier for cold forming of metallic micro-scale components. 
   
   
       8 . The use according to  claim 6  for the electroplating of a copper substrate, wherein the electrochemically deposited alloy is SnZn and the chemical etching of the Zn phase is carried out with diluted hydrochloric acid. 
   
   
       9 . A microporous layer for lowering friction in metal forming processes, said layer being produced by a process according to  claim 1 . 
   
   
       10 . Use of a microporous layer, said layer being produced by a process according to  claim 1 , and lubricated with a liquid, such as a mineral oil or an organic oil, with a viscosity low enough to penetrate into the pores of the porous coating for lowering friction in metal forming processes.