Cathodic protection by coating for cooling circuits or other holes or channels

Abstract

The present invention develops dies, moulds, tools, workpieces and structures with active protection against corrosion (cathodic protection) in cooling circuits, often internal, independent of its complexity. Moreover, the protection can be renewed if considered appropriate. The protection is achieved through a thin coating layer which contains metallic elements more electronegative than the substrate to be protected and which is properly adhered to the mentioned substrate in order to ensure an efficient cathodic protection.

1 . Steel-based mould, die, tool, workpiece or structure comprising cooling circuits and/or holes, characterised in that the cooling circuits and/or holes are at least partly coated with at least a material offering cathodic protection to the underlying substrate. 
     
     
         2 . Steel-based mould, die, tool, workpiece or structure according to  claim 1 , wherein the material offering cathodic protection to the substrate comprises a mixture containing embedded particles or pigments made of at least one of Al, Zn, Mg and/or Sn. 
     
     
         3 . Steel-based mould, die, tool, workpiece or structure according to  claim 2 , wherein the embedded particles are made of alloys of at least one of Al, Zn, Mg and/or Sn, provided that these alloys are electronegative with respect to the underlying substrate in order to offer active protection against corrosion. 
     
     
         4 . Steel based mould, die, tool, workpiece or structure according to  claim 1 , wherein the material offering cathodic protection to the substrate is a sol-gel lacquer. 
     
     
         5 . Steel based mould, die, tool, workpiece or structure according to  claim 1 , wherein the underlying substrate comprises a high thermal conductivity steel with a conductivity higher than 42 W/mK. 
     
     
         6 . Method of manufacturing steel-based moulds, dies, tools, workpieces or structures having cooling systems and/or holes, which method comprises the step of at least partly coating the cooling systems and/or holes with a coating offering cathodic protection to the underlying substrate. 
     
     
         7 . Method according to  claim 6 , wherein the underlying substrate is coated by means of a wet chemical method. 
     
     
         8 . Method according to  claim 6 , wherein the underlying substrate is coated using a sol-gel lacquer. 
     
     
         9 . Method according to  claim 8 , wherein the surface of the underlying substrate is activated prior to the application of the sol-gel lacquer. 
     
     
         10 . Method according to  claim 9 , wherein the surface of the underlying substrate is activated by picking. 
     
     
         11 . Method according to  claim 9 , wherein the surface of the underlying substrate is activated by etching. 
     
     
         12 . Method according to  claim 9 , wherein the surface of the underlying substrate is activated using HCl. 
     
     
         13 . Method according to  claim 9 , wherein the surface of the underlying substrate is activated using HNO 3 . 
     
     
         14 . Method according to  claim 9 , wherein the surface of the underlying substrate is activated using HF. 
     
     
         15 . Method according to  claim 6 , comprising the following steps:
 activating the surface of the underlying substrate with a media aggressive for said surface;   neutralizing the rests of the aggressive media; and   applying of a sol-gel lacquer to the activated surface.   
     
     
         16 . Method according to  claim 15 , wherein, after the neutralization step, the rests of the aggressive media are removed with an organic solution. 
     
     
         17 . Method according to  claim 15 , wherein, after the neutralization step, the rests of the aggressive media are removed with an inorganic solution. 
     
     
         18 . Method according to  claim 16 , wherein, after the removal of the rests of the aggressive media, the surface of the substrate is washed with a universal solvent. 
     
     
         19 . Method according to  claim 9 , wherein the lacquer is applied within one day after the surface activation. 
     
     
         20 . Method according to  claim 9 , wherein the lacquer is applied within two hours after the surface activation. 
     
     
         21 . Method according to  claim 9 , wherein the lacquer is applied within one hour after the surface activation. 
     
     
         22 . Method according to  claim 9 , wherein the lacquer is applied within half an hour after the surface activation. 
     
     
         23 . Method according to  claim 6 , further comprising a drying step. 
     
     
         24 . Method according to  claim 23 , wherein the holes are filled with the sol-gel lacquer during the drying step. 
     
     
         25 . Method according to  claim 23 , wherein the lacquer, either undiluted or diluted, is recirculated through the holes during the drying step. 
     
     
         26 . The method of  claim 6 , comprising plastic injection. 
     
     
         27 . The method of  claim 6 , comprising aluminium injection. 
     
     
         28 . The method of  claim 6 , comprising hot plate stamping.