US140924A - Improvement in the electro-deposition of aluminum - Google Patents

Description

'NITED STATES PATENT FFIGE.

JOHN A. JEANQON, OF NEWPORT, KENTUCKY.

IMPROVEMENT IN THE ELECTRO-DEPOSITION OF ALUMINUM.

Specification forming part of Letters Patent No. 140,924, dated July 15, 1873; application filed November 1, 1872.

To all whom it may concern:

Be it known that I, J OHN A. JEANgoN, of Newport, Campbell county, State of Kentucky,

have invented a certain new and useful Process for Plating Metallic Surfaces with Aluminum, of which the following is a specification:

My invention consists of a process by which I plate with aluminum obtained from aqueous solutions of its salts. 1

In carrying out my invention, I first dissolve any desired quantity of a salt of aluminum,

such as the sulphate, muriate, nitrate, acetate, cyanide, &c., or the double salt of aluminum and potassium, sodium, ammonium, or other metals, in distilled water, and concentrate the solution to 20 Baum, (at 50 Fahrenheit,) put it in a vessel suitable in size to commodi= ously hold the articles to be plated. This vessel is to serve as a precipitating-trough. I then take either four pairs of Smees zincoplatinum plates, or three of Bunsens zincocarbon, their sizes to correspond to the work i to be done, and connect the elements of either 1 series intensity fashion, and adapt a thick copper wire or brass wire to each terminal plate of the series to serve as conductors for the anode and cathode in the solution in the precipitating-vessel. I then heat this solution by means of steam, or otherwise, to 140 Fahrenheit, and add a small quantity of such acid as the salt in solution contains to it-in case of a cyanide, dilute sulphuric acid, to slightly acidulate and maintain as near as possible this temperature during the whole operation.

After charging either series with dilute sulphuric acid in case of Smees, with sulphuric and nitric dilute acids in Bunsens, battery, I connect it with the precipitating-vessel as follows: Attach a plate of the metal aluminum, of a size suitable to the number and sizes of the articles to be plated, to the wire connected with the terminal negative plate of the battery, the aluminum-plate forming the anode.

The other wire, connected with the positive terminal-plate, may be attached to a wire frame orother metallic device on which to suspend the articles to be plated. It is advisable to have both wires of about the same length for the better conduction of an even current. As soon as the battery is in motion I dip the anode and the articles to be plated into the solution, and leave them therein until the desired thickness of the coat is deposited upon them. The articles must be well cleaned before placing them in the decomposition-trough. When they have received the necessary deposit I remove them from the trough and dip them into a warm and weak solution of carbonate of potash or soda. Afterward I wash them in clean water, and dry and polish them.

In order to insure an uniform ldeposit care must be taken during the operation to regulate the intensity and quantity of the current to the strength of the solution of each salt used, for the different salts offer different degrees of resistance to the current. The quantity of hydrogen evolved at the cathode durin g the operation in the depositing-vessel willalways to a great extent indicate the intensity of the current. It is also necessary to add occasionally during the operation (in measure as the water and part of the acid in the de composing solution evaporate) acidulated water to prevent its becoming too much concentrated, and impeding thereby the uniformity of the texture of the deposit.

When solutions of aluminates are used for aluminum deposit, as may be sometimes very advantageously, the above-described process must be somewhat modified. The battery must be of large series, eight or ten elements, the plates to be connected quantity fashion, and the acting fluid very dilute acid, one per cent. of acid being sufficient. The solution in the decomposition-vessel must contain an excess of the alkaline hydrate forming the base of the respective alnminate, and the temperature be at least 200 Fahrenheit, and the anode very small in proportion to the cathode. A

'plantinum anode is much better to be used deposit has been thereby so thin, and the time I claimso slow, as to make these processes practically The herein-described process for aluminum useless. plating, by means of electricity from aqueous By using the process and taking the neoessolutions of the salts of aluminum, substansary care, as described herein, the whole work tially as herein specified.

can be carried on at will in the regulation of JOHN A. J EANQON.

the thickness, density, or texture, such as crystalline, sandy, or black deposit, or regular Witnesses:

plate of any desired speed in depositing can N. B. MALER,

be attained with the greatest certainty, and J OHN RUPPERT.

rendered practically useful.