Method for deposition of hard chrome layers

Abstract

The present invention concerns a method for galvanic deposition of a hard chrome layer on a substrate surface at high rates of deposition. According to the invention, the substrate surface being coated makes contact at reduced pressure relative to the ambient pressure with a chromium-containing electrolyte suitable for galvanic deposition and a relative motion between substrate surface and electrolyte is produced during the depositing of the chrome layer on the substrate surface.

1 - 9 . (canceled) 
     
     
         10 . A method for depositing of a hard chrome layer on a substrate surface comprising:
 making contact between the substrate surface and a chromium-containing electrolyte;   applying a pulsed current between the substrate surface and a counterelectrode for the deposition of a first hard chrome layer on the substrate surface,   wherein the deposition of the first hard chrome layer occurs in a container essentially gas-tight to the surroundings and at a reduced pressure relative to ambient pressure, the substrate surface and chrome-containing electrolyte are moved with a velocity of between 0.1 m/s to 5 m/s relative to each other; and   applying a second hard chrome layer over the first hard chrome layer.   
     
     
         11 . The method of  claim 10  wherein the second hard chrome layer is deposited on the first deposited hard chrome layer using a direct current. 
     
     
         12 . The method of  claim 10  wherein the reduced pressure has a pressure difference of 10 mbar to 800 mbar relative to ambient pressure. 
     
     
         13 . The method of  claim 10  wherein the reduced pressure has a pressure difference of 20 mbar to 200 mbar relative to ambient pressure. 
     
     
         14 . The method of  claim 10  wherein the pulsed current has a frequency of 5 Hz to 5000 Hz. 
     
     
         15 . The method of  claim 10  wherein the pulsed current has a frequency of between 50 Hz and 1000 Hz. 
     
     
         16 . The method of  claim 10  wherein the first hard chrome layer is deposited at a current density between 25 A/dm 2  and 1000 A/dm 2 . 
     
     
         17 . The method of  claim 10  wherein the first hard chrome layer is deposited at a current density between 50 A/dm 2  and 500 A/dm 2 . 
     
     
         18 . The method of  claim 10  wherein the second hard chrome layer is deposited by direct current at a current density in the range between 25 A/dm 2  and 1000 A/dm 2 . 
     
     
         19 . The method of  claim 10  wherein the layers are deposited at an electrolyte temperature between 30° C. and 85° C. 
     
     
         20 . The method of  claim 10  wherein the electrolyte has a pH of ≦pH 3. 
     
     
         21 . A method for depositing of a hard chrome layer on a substrate surface comprising:
 making contact between the substrate surface and a chromium-containing electrolyte;   applying a pulsed current between the substrate surface and a counterelectrode for the deposition of a first hard chrome layer on the substrate surface, and applying a direct current between the first hard chrome layer and the counterelectrode for deposition of a second hard chrome layer;   wherein the deposition of the first hard chrome layer and second hard chrome layer occurs with a single electrolyte in a container essentially gas-tight to the surroundings and at a pressure reduced by between 10 mbar and 800 mbar relative to ambient pressure, the substrate surface and chrome-containing electrolyte are moved with a velocity of between 0.1 m/s to 5 m/s relative to each other, the pH is <3, the pulsed current frequency is from 5 to 5000 Hz, the current density is between 25 and 1000 A/dm 2 , and the electrolyte temperature between 30° C. and 85° C.   
     
     
         22 . The method of  claim 21  wherein the pressure reduced by between 20 mbar and 200 mbar relative to ambient pressure, the substrate surface and chrome-containing electrolyte are moved with a velocity of between 1 m/s to 5 m/s relative to each other, the pH is <1, the pulsed current frequency is from 50 to 1000 Hz, and the current density is between 50 and 500 A/dm 2 . 
     
     
         23 . A substrate comprising a hard chrome layer deposited by the method of  claim 10 .