US1144000A

US1144000A - Treament of surfaces of aluminum or alloys of aluminum in order to prepare them for receiving a metallic deposit.

Info

Publication number: US1144000A
Application number: US81306214A
Authority: US
Inventors: Francois Auguste Roux
Original assignee: ALUMINUM FRANCAIS SOC D
Current assignee: D'ALUMINUM FRANCAIS Ste; ALUMINUM FRANCAIS SOC D
Priority date: 1914-01-19
Filing date: 1914-01-19
Publication date: 1915-06-22
Anticipated expiration: 1932-06-22

Description

STATES PATENT. OFFICE.

rnANcoIs nu'eus'rn ROUX,

or PARIS, ERANCE, ASS-IGNOR'TO socrn'rn rnauoars, or rams, rnanon.

TREATMENT OF SURFACES OF ALUMINUM OR ALLOYS F ALUMINUM IN ORDER- TO No Drawing. I

- To all whom it may concern Be it known that I, FRANgoIs AUeUs'rE Roux, a citizen of the Republic of France, and resident of Paris, France, have invented new and useful improvements relating to the treatmentof surfaces of aluminum or alloys of aluminum in order to prepare them for receiving a metallic deposit, which are fully deposited on the said surface. To overcome this difiiculty various methods have already been proposed. One of the processes consistsin submitting aluminum to the action of baths which precipitate, on its surface,-

heavy metals having for object .to prevent its oxidation. According to another method,

and with the same end in view, a solution of a' neutral metallic fluorid .is employed in a neutral alkaline salt derived from an or *ganic acid. It is also possible to bring consecutively into action both the solutions, by beginning with the first named. However these processes have the disadvantage of leaving on the aluminum, at the moment when it introduced. into h the galvanic baths, a pulverulent deposit which a'rinsing and even a brushing are not able to remove,

and which. a passage through an acid bath would wholly eliminate, leaving the oxidized met-a1 bare. hlnsuch .instance, perfect adherence of the metals to be deposited is im possible. If placed into the baths with the pulverulent deposit, the deposits are rough and lend themselves poorly to polishing, and

at the same time theyare liable to disappear at certain points'in the electrolytic baths,

from which there, results an incomplete ad-.

herence ofthe deposited metal.

The present process consists n submitting the aluminum surfaces, previously cleansedby any known means, to the action of diluted hydracids or of diluteda'lkalis,

ity to the to whichhas PREPARE THEM FOR RECEIVING- A METALLIC DEIQSIT.

Specification of Letters Patent. Patented J 11119 22, 1915 Application filed J'anuaryw, 1914. Serial No. 813,052.

been added a salt of tin or of another soluble I metal; then, after rinsing the said surfaces are passed through a salt solution that is capable of fixing on them the tin or other metal and at the same time of expelling the hydrogen which was inclosed in the pulverulent metallic deposit formed on the aluminum. The aluminum salts and the alums in asaturated and more or less warm solution reali'ze particularly well this latter condition, all the more asthey have the property of dissolving the metallic oxids, which is very advantageous for the performing of the process. W

In carrying out the present invention, the aluminum surface to be coated is cleansed by any method, for instance by a solution ofsoda or potash at about 5%, Whihh is preferably employed when l 'ot; then the last traces of alkali are washed away or neutralized, if

LALUMINIUM necessary, in a bath of diluted sulfuric or.

nitric acid, or in a mixture of both these acids; after that, the metal, having first been thoroughly rinsed in water, is immersed in a diluted solution of a hydracid or an alkaline hydrate at about 5 degrees Baum, to which is added a salt of tin or of another soluble metal. For instance tin chlorid in the proportion of 1% gives good results.

The articles are then quickly and thoroughly rinsed, after which they are immersed into a saturated solution, preferably in a heated 'state, of 'an aluminum salt. Ammonia alum isespeciall'y to;be' recommended- During the operation the hydrogen inclosed in the layer of soluble metal depositedon the aluminum escapes violently and atthe same time it removes mechanically the pulverulent deposit which is in excess, it prevents the oxidation of aluminum and gives tenactin or heavy metal deposit. The

aluminum. after having been so treated is .then rinsed,'and subsequently immersed'in a solution "of a diluted mineral acids1 1lfur ic or nitr1cthe'efi'ect thereof conslsting 1H dissolving the last traces of the metallic precipitate of*which' the adherence would not be sufficient to ofi er-a proper resistance to the electrolytic baths. Ihelatter operation is notabsolutely indispensable. -.Having been rinsed, thealuminum is readyto receive allelectrolytiOdePosits. It also may be kept in abeyance in pure Water, or it may be dried. In any case its surface will not become oxidized and will always remain fit to receive a metallic deposit.

l/Vhat I claim is: e r 1. A process of treating surfaces of aluminum or its alloysto prepare-them for receiving a metallic deposlt, which consists in subjecting the previously cleansed surfaces to the action of a weakbath containing a hydrac'id holding a .soluble metal in solution,

- thereby to precipitatea dep sit of said soluble metal upon said surfa'stand to liberate'hydrogen which remains occluded in the deposit where it adheres to said surfaces,

rinsing said surfaces, and passing the surfaces through a hot bath constituted by a saturated solution of a salt capable of expelling the occluded hydrogen and of fixing on saidsurfaces thesoluble metal employed.

2. A process of treating surfaces of aluminum or its alloys to prepare them for receiving a metallic deposit; which consists in sub- 7 Jecting the previously cleansed surfaces to the action of a weak bath containinga hydracid holding'tin in solution, thereby to precipitate .a deposit of tin upon said surfaces and to liberate hydrogen which remains occluded. in the deposit where it adheres tosaid surfa'ees, rinsing said surfaces, and passing :the surfaces through a hot bath constituted by {a saturated solution of a salt capable of expelling the occluded hydrogen and offixing the tin on said surfaces.

3. A process of treating surfaces of aluminum or its alloys to prepare them for receiv-' ing a metallic deposit, which consists in subjecting the previously cleansed surfaces to the action of a weak bath containing a hydracid holding tin in said surfaces, and passing them through a solution, rinsing hot bath constituted by a saturated solution of an aluminum salt. 4. A process of treating surfaces of aluminum or its alloys to prepare them for receiving a metallic deposit, which consists- 1n sub ecting the previously cleansed sur faces to the action of a weak bath containing a substance holding a soluble metal in solution, thereby to precipitate a deposit of said soluble metal upon said surfaces and Y to liberate hydrogen which remains occluded 1n the deposit where 1t adheres to sald surfaces, rinslng said surfaces, and passing the surfaces through a hot bath constituted by a saturated solution of a salt capable of expelling the occluded hydrogen and of fixing on said surfaces the soluble metal employed.

Y 5. A process of treating surfaces of alumi num or its alloys to prepare them for receiving a metallic deposit, which consists in subjecting the previously cleansed surfaces to the action of a weak bath containing a hydracid holding a soluble metal .in solution, thereby toprecipitate a deposit ofsaid solube metal upon said surfaces and to liberate hydrogen which remains occluded in the deposit where it adheres to said surfaces, rinsing said surfaces, passing the surfaces through a hot bath constituted by a saturated solution of a salt capable of expelling the occluded hydrogen and of fixing onsaid surfaces the soluble metal employed, and