Trivalent Chromium Electroplating Solution and an Operational Method Thereof

Abstract

A trivalent chromium-based electroplating solution in accordance with the present invention a trivalent chromium salt, a bivalent nickel salt, a complex agent, a conductive salt, a buffering agent and an additive for electroplating a chromium-nickel alloy deposit on a component. By using the lowly toxic trivalent chromium to substitute highly toxic hexavalent chromium, an electroplating procedure with the present trivalent chromium-based electroplating solution has less pollution and high current efficiency to allow the electroplating performing at the room temperature.

1 . A trivalent chromium electroplating solution comprising a water solution added with 0.1-1.2 mole/L of a trivalent chromium salt; 0.1-0.8 mole/L of a bivalent nickel salt; 0.1-4.0 mole/L of a complex agent; 1.0-3.0 mole/L of a conductive salt; 0.1-0.8 mole/L of a buffering agent; and 0.01-0.30 mole/L of an additive. 
   
   
       2 . The trivalent chromium electroplating solution as claimed in  claim 1 , wherein the trivalent chromium salt selected from the group consisting of chromium chloride, chromium sulfate, or a hydrate of each forgoing salt. 
   
   
       3 . The trivalent chromium electroplating solution as claimed in  claim 1 , wherein the bivalent nickel salt is selected from the group consisting of nickel chloride, nickel sulfate, or a hydrate of each forgoing salt. 
   
   
       4 . The trivalent chromium electroplating solution as claimed in  claim 1 , wherein the complex agent is selected from the group consisting of urea (carbamide), glycine (aminoacetic acid), hydroxyacetic acid, formic acid or a dissoluble salt of each forgoing acid. 
   
   
       5 . The trivalent chromium electroplating solution as claimed in  claim 1 , wherein the conductive salt is selected from the group consisting of ammonium chloride, sodium chloride, potassium chloride, magnesium chloride, ammonium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate or a mixture of forgoing salts. 
   
   
       6 . The trivalent chromium electroplating solution as claimed in  claim 1 , wherein the buffering agent is selected from the group consisting of boric acid, aluminum chloride, aluminum sulfate or a mixture of foregoing components. 
   
   
       7 . The trivalent chromium electroplating solution as claimed in  claim 1 , wherein the additive is selected from the group consisting of ammonium bromide, sodium bromide, potassium bromide or a mixture of foregoing components. 
   
   
       8 . An electroplating procedure with a trivalent chromium-based electroplating solution comprising a water solution added with 0.1-1.2 mole/L of a trivalent chromium salt; 0.1-0.8 mole/L of a bivalent nickel salt; 0.1-4.0 mole/L of a complex agent; 1.0-3.0 mole/L of a conductive salt; 0.1-0.8 mole/L of a buffering agent; and 0.01-0.30 mole/L of an additive to deposit a chromium-nickel coating layer, the operational method comprising steps of:
 arranging a component, auxiliary electrodes, and the trivalent chromium-based electroplating solution in a tank;   setting the component and the auxiliary electrodes to contact the trivalent chromium-based electroplating solution; and   providing a fixed current or potential between the component and the auxiliary electrodes by an additional power supplier.   
   
   
       9 . The operational method as claimed in  claim 8 , wherein a temperature of component surfaces lies in a range from 1° C. to 50° C. 
   
   
       10 . The operational method as claimed in  claim 8 , wherein the fixed current provided by the additional power supplier has a range from 1 to 90 ampere per square decimeter. 
   
   
       11 . The electroplating procedure as claimed in  claim 8 , wherein the auxiliary electrodes are made of material selected from the group comprising a titanium mesh coated with platinum, platinum, graphite and stainless steel.