US2638410A

US2638410A - Brightening nickel

Info

Publication number: US2638410A
Application number: US206314A
Authority: US
Inventors: Walter G Zelley
Original assignee: Aluminum Company of America
Current assignee: Howmet Aerospace Inc
Priority date: 1951-01-16
Filing date: 1951-01-16
Publication date: 1953-05-12
Anticipated expiration: 1970-05-12

Description

Patented MaylZ, 1953 BaiGHTENING Nickel Walter G. Zelley, New Kensington, Pa assignor to Aluminum Company of'America, Pittsburgh,

Pa., a corporation of Pennsylvania" inoinrtwsi. Application January 16,1951, Serial No. 206,314 51 j.

This invention relates tov solutions and methods for the chemical brightening of nickel. As used herein, the term nickel includes pure vnickel, commercial nickel containing the usualimpurities, nickel base alloys, and nickel plated upon other metals.

According to my invention, nickel surfaces may be readily brightened by simply immersing them for a short time in certain hot aqueous solutions containing phosphoric acid, sulfuric acid and nitric acid.

In the past bright nickel plated surfaces have usually been produced in so-called bright nickel baths, or by bufiing the nickel plates produced in s o-called dull or semi-bright nickel baths. Bright nickel baths are difiicult to maintain in satisfactory condition and do not produce nickel plates having all the desired properties of the other types of baths. On the other hand, bufling is an expensive finishing procedure, and also is not conveniently employed for treatin small articles or a variety of different articles. Many efforts have been made to brighten nickel and nickel plated surfaces in simple chemical solutions, but few such treatments have been successful, particularly for the production of surfaces which are both smooth and bright.

An object of this invention is to provide a convenient method for brightening nickel surfaces, particularly nickel plated surfaces. Another object is to provide a simple chemical solution and method for brightening nickel surfaces, thus minimizing or eliminating the need for bufling of such surfaces. These and other objects will be apparent in the following description of the in vention.

The solutions that may be employed in accord ance with the invention must comprise, as the essential component thereof, on a weight basis referred to the total weight of phosphoric acid, sulfuric acid, nitric acid and water therein, about 45 to 60 per cent phosphoric acid (H3PO4), about to per cent sulfuric acid (HzSOi) about 8 to 15 per cent nitric acid (HNOs) and. about 10 to 20 per cent water (H2O). The stated water content of the solutions just referred to, and also of those hereinafter referred to, is the entire water content thereof, whether added with the other components or separately. For optimum results such solutions comprising about to per cent phosphoric acid, about 18 to 23 per cent sulfuric acid, about 10 to 13 per cent nitric acid and about 12 to 18 per cent water should be employed.

A solution consisting essentially of the four 5 Claims. (o1.- 41-421) components specified above, within the limits.

stated, is very effective for brightening nickel surfaces. However, a solution in which the components specified above constitute but a predominant part of the total is also contemplated. Limited amounts of impurities, dissolved metals.

or other components may be contained in the solution, for example.

The composition of the solution and the temperature at which it is employed are very important. It is only when phosphoric acid, sulfuric acid and nitric acid are mixed in certain proportions, with an appropriate amount of water, that a brightening solution for nickel is produced. Further it is only when such a solution is employed at temperatures above about C. that it is effective for improving the brightness and smoothness of nickel surfaces. To obtain the best results the solution used should be moderately agitated and maintained at a temperature between about and 90 C.

The period of immersion will vary with the type of nickel being treated and the temperature of the solution. Generally from about 1 minute to 3 minutes is adequate to effect the removal of about 0.0002 to 0.0003 inches of nickel from the surface being treated, and thus effect good polishing thereof. Shorter periods of time are often sufficient; and longer periods of time may be employed, but do not appear to produce superior results. A single immersion in the solution is, of course, ordinarily sufiicient.

Surfaces of various types of nickel may be treated in the solution with beneficial results. Surfaces of high brilliancy and smoothness are obtained on nickel plates, for example, thus facilitating the'production of smooth plates superimposed thereon.

A typical solution for use in accordance with the invention contains the following components:

Per cent by weight H3PO4 52 H2804 21 HNOs 12 H2O 15 Such a solution may be readily made up from reagent strength acids, as follows:

Milliliters per liter Phosphoric acid 600 Sulfuric acid (96%) 200 Nitric acid (70%) 2 0 in which case no added water is required.

During use of the solutions described, various components may be volatilized or decomposed, but the solutions may be readily re-constituted by appropriate additions of components which have reached too low a concentration. Nitric acid additions, for example, must be made from time to time in order to replace amounts which are used up.

It will be understood that brightened nickel surfaces produced in accordance with the invention may be suitably protected by lacquers, employed as a base for chrome plating thereoven or used directly as made.

I claim:

1. A method for chemical brightening-o1 nickel which comprises immersing a nickel article in a solution consisting essentially of a about .45 to 60 per cent phospheric acid, about '15 to 25 per cen sulfuric acid, about 8 to per cent nitric acid and about 10 to per cent water, on a weight basis referred to the total Weight of the aforemid components, the solution bemg maintained at a temperature above about v.65 C.

2. A method for chemical brightening of nickel which comprises immersing a nickle article a solution consisting essentially of about'fio to per cent phosphoric acid, about 18 to 23 per cent sulfuric acid, about v10 to 13 per cent nitric acid 4 and about 12 to 18 per cent water, on a weight basis referred to the total weight of the aforesaid components, the solution being maintained at a temperature between about 15 and 90 C.

3. A method according to claim 1 wherein the article is immersed for a period of about 1 to 33mm.

$1. method according to claim 2 wherein the article is immersed for a period of about 1 to V3 vminutes.

5. A method for chemical brightening of nickel which comprises immersing a nickel article for about 11 to :3 minutes in a solution Consisting oi about :52 :per cent :phosphoric acid, about 21 p cent isulmric :acid, about 12 per cent nitric acid and 15 per cent water, on a Weight basis, the solution being maintained at a temperature between about and C.

WALTER G. ZELLEY.

Reicrenccs Cited in the file of this patent UNITED STATES PATENTS Number Name Date 25 $154355 Kepier M Apr. 1-8, 1939 2,337,062 Page 'Dec. 21, 1943 2,434,021 Thompson et a1. Jan. 6, I948

Claims

1. A METHOD FOR CHEMICAL BRIGHTENING OF NICKEL WHICH COMPRISES IMMERSING A NICKEL ARTICLE IN A SOLUTION CONSISTING ESSENTIALLY OF ABOUT 45 TO 60 PER CENT PHOSPHERIC ACID, ABOUT 15 TO 25 PER CENT SULFURIC ACID, ABOUT 8 TO 15 PER CENT NITRIC ACID AND ABOUT 10 TO 20 PER CENT WATER, ON A WEIGHT BASIS REFERRED TO THE TOTAL WEIGHT OF THE AFORESAID COMPONENTS, THE SOLUTION BEING MAINTAINED AT A TEMPERATURE ABOVE ABOUT 65* C.