US1681521A - Process of cleaning and burnishing metallic powders - Google Patents

Description

Patented Aug. 21, 1928.

nairsn STATES) PATENT OFFICE.

JOHN A. DALY, on NEW ROCHELLE, new YORK.

PROCESS OF CLEANING AND BURNISI-IING METALLIC POWDERS.

No Drawing.

metallic surface with metal, to apply to said substance a metallic powder, causing the same to adhere thereto either by embedding the powder in a sticky substance applied to the substance to be coated, or mixing the metallic powder with some substance in the nature of a lacquer or varnish, to render the coating conductive, and thereafter placing the thus coated substance or article in an electrodepositing bath for electrodeposition.

Great difficulty has been experienced in these processes in securing a perfect and even strike of the electrodeposited metal. This difliculty has made it necessary to attach to the article or substance to be coated a number of attachments, and, in the case of large articles, a considerable number of such attachments has been necessary. Even after such practice, it has been necessary to leave the substance to be coated in the bath for c0nsiderable periods before a good strike could be secured, and in the case of some large articles it has been found impossible to secure a satisfactory electrodeposition.

In the former practice also it is found that the portions of the substance in which a successful strike was required become conductive in advance of the remaining portions, thus developing a coating of uneven thickness, which is exceedingly objectionable.

By use of powder obtained according to the present method a perfect strike may be secured over the whole of the article or substance in a short space of time, and a coating of uniform thickness may be produced using but a single attachment for electrical current to the substance or article to be coated.

It has been found that a particularly good strike can be secured by applying a coating of powder of tin-lead alloy, which substances Application filed August 2, 1926. Serial No. 126,748.

are readily onidized if exposed to the air, and by the provision of the present invention these particles may have their surfaces effectively cleaned of oxidation or other adhering particles, whereupon they may be used upon the electrodeposition process.

For the purpose of cleaning these particles 1 it has beendiscovered that they may be mi Xed with particles of a substance harder than themselves and agitated while thus mingled 'whi chwill result in the effective cleaning of the particles of the powder.

Operative substances as cleaning elements are found to be glass beads, preferably of small diameter, or small steel elements, and a desirable proportion of cleaning elements to powder is found to be four parts of the powder to one part of the cleaning elements.

\Vhile glass beads are found satisfactory for the purpose an objection to their use is found in static electricity, which is produced by the agitation and with which the glass beads become charged upon their surfaces, thus causing the particles of the powder to adhere together or to the container. For this reason it is preferred to use the steel elements as a cleaningmedium.

The elements referred to with the powder mingled therewith may be. placed in any container and shaken by hand or machinery. It is desirable to utilize the ordinary tumbling barrel of the nature used by jewelers in cleaning small articles of jewelry.- After an agitation of from five to thirty minutes the powder will be found to have its par ticles provided with. bright surfaces, which may then be separated from the cleaning element and applied to the article to be electrically coated in the manner above referred to.

Since a substantially instantaneous strike maybe produced upon the immersion of the coatedarticle in the electroplating bath and because of the fine electrically conductive condition of theparticles a single attachment for current to the article to be coated is sufficient to produce an even electrodeposition over the whole of the article.

1. The process of burnishing metals in a state of line subdivision which comprises commingling the particles of metal with powder with separated particles of steel and agitating the mixture.

4:. The process of burnishing powdered lead tin alloy which comprises mixing four parts of the powder with one part of small steel elements and agitating the mixture.

JOHN A. DALY.