Process for forming a gold-chromium alloy from an electrodeposited gold-chromium surface
AssigneeAmerican Standard Inc.
InventorJohn Joseph Liska
Life of this patent
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Abstract
The invention relates to a process for heat diffusion of an electrodeposited gold layer on a chromium surface by simultaneously depassivating and cathodically gold plating a chromium surface by immersion and electroplating into an acid gold bath solution and diffusing the gold-chromium coating by heat to form a gold-chromium alloy which is abrasion resistant and which has a hardness substantially greater than that of a gold plated coating on a chromium surface which has not been heat diffused.
Claims13
A process for the heat diffusion of an electro-deposited gold layer on a chromium surface to form abrasion resistant gold-chromium alloy consisting essentially of:
- simultaneously depassivating and cathodically gold plating the chromium surface in an aqueous acid gold plating solution having a gold content of about 0.2 to 2 tr. ozs. per gal, a pH of less than 2 and maintaining said gold solution at about room temperature to about 120.degree. F. whereby the weight loss of said chromium surface is less than 0.01 mg/in.sup.2 /min;
- said surface being plated in said plating solution for a period of time of from about 5 secs. to about 5 mins. at a current density of from about 1 ampere per square foot to about 200 amperes per square foot whereby the amount of gold deposited over said depassivated chromium surface is sufficient to form an alloy with said chromium layer while maintaining a gold color;
- removing the gold-chromium plated surface from said plating solution, water rinsing;
- and
- thereafter heat diffusing the gold plated chromium surface to form a gold-chromium alloy by subjecting said gold-chromium surface to elevated temperatures of from about 650.degree. F. to about 900.degree. F. for a period of time of from about 2 minutes to about 6 hours whereby a gold-chromium alloy surface is produced which has a hardness and is more abrasion resistant than the same gold coating which has not been heat diffused.
A process for the heat diffusion of an electro-deposited gold layer on a chromium plated plumbing fitting to form an abrasion resistant gold-chromium alloy finish consisting essentially of:
- simultaneously depassivating and cathodically gold plating the chromium plated plumbing fitting in an aqueous acid gold plating solution having a gold content of about 0.2 to 2 tr. ozs. per gal., pH of less than 2 and maintaining said gold plating solution at about room temperature to about 120.degree. F. whereby the weight loss of said chromium plated fitting is less than 0.01 mg/in.sup.2 /min;
- said surface being plated in said plating solution for a period of time of from about 5 secs. to about 5 mins. at a current density of from about 1 ampere per square foot to about 200 amperes per square foot whereby the amount of gold deposited over said depassivated chromium plated fitting is sufficient to form an alloy with said chromium plated fitting while maintaining a gold color;
- removing the gold-chromium plated surface from said plating solution, water rinsing;
- and
- thereafter heat diffusing the gold plated chromium surface to form a gold-chromium alloy by subjecting said gold-chromium surface to elevated temperatures of from about 650.degree. F. to about 900.degree. F. for a period of time of from about 2 minutes to about 6 hours whereby a gold-chromium alloy surface is produced which has a hardness and is more abrasion resistant than the same gold coating which has not been heat diffused.
A process for the heat diffusion of an electro-deposited gold layer on a chromium plated plumbing fitting to form an abrasion resistant gold-chromium alloy finish comprising:
- simultaneously depassivating and cathodically gold plating a chromium plated plumbing fitting in an aqueous acid gold plating solution having a gold content of about 0.2 to 2 tr. ozs. per gal, a pH of less than 2 and maintaining said gold solution at about room temperature to about 120.degree. F.;
- said chromium plated fitting being plated in said plating solution for a period of time of from 5 secs. to about 5 mins. at a current density of from about 1 ampere per square foot to about 200 amperes per square foot;
- removing the gold-chromium plated fitting from said plating solution, water rinsing;
- immersing said aqueous gold plated fitting in a second aqueous gold plating solution having a pH of from 3.3. to 4.0;
- a gold content of from 0.15 to 0.5 tr. oz. per gal.;
- at a current density of from 10 amperes per square foot to about 30 amperes per square foot;
- for a period of time of from 1 min. to about 2 mins. to provide a 24 Karat gold finish;
- and
- thereafter diffusing the gold plated chromium surface on said fitting to form a gold-chromium alloy by subjecting said gold-chromium fitting to elevated temperatures of from about 650.degree. F. to about 900.degree. F. for a period of time of from about 5 mins. to about 6 hrs. whereby a gold-chromium alloy surface on said plumbing fitting is produced which has a hardness and is more abrasion resistant than the same gold coating which has not been heat diffused.
Dependencies are inferred from the claim text.