US1254056A - Process of making metal powder. - Google Patents

Description

w. c. MOORE.

PROCESS OF MAKING METAL POWDER.

' APPLICATION FILED JULY 29, I915- Patented Jan. 22, 1918.

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WILL: .MD on: BY 4Q ad 4 TTORNEY WITNESS jVTW UNITED STATES PATENT OFFICE.

WILLIAM G. moons, or LAKEWOOD, omo, ASSIIGNOR, :BY' MESNE ASSIGNMENTS, 'ro

' NATIONAL CARBON COMPANY, INC., A CORPORATION OF NEW YORK. I

PROCESS OF MAKING 'METAL POWDER.

Specification of Letters Patent.

Patented J an.22 ,1918.

Application filed July 29, 1915. Serial No. 42,527.

To all whom it may concern:

Be it known that I, WILLIAM C. MOORE, a citizen of the United States, residing at Lakewood, in the county of Cuyahoga and State of Ohio, have invented a certain new and useful Improvement in Processes of- Making Metal Powder, of which'the following is a full, clear, and exact description.

My invention relates to the making of metal powders and also to current collecting brushes made from the same.

My invention is an improvement over prior processes in that relatively simple ap-' paratus is required and the metal powder is obtained in a substantially pure condition. The advantages of the improvement will be apparent on reading the appended description, reference being also had to the drawcathode surface were used, the copper would I late out in a smooth, adherent coating on the cathode when current is sent through the cell. Desiring to secure the metal in a loose, powdery condition, I follow an opposite course and send through a current of high density in regard to cathode surface- In view of this, it is advisable to use a copper wire-as cathode, while the anode may be a heavy copper plate. I

When a current of. high density is used,

copper is deposited out on the cathode in the form of fine powder which loosely collects thereon, as indicated at 5' on the drawing.

The powder must not be allowed to accumulate on the cathode to any great extent for it naturally increases the surface of the cathode which. at the same time cuts down the amperes per square inch cathode surface.

If low current density per square inch of somewhere near constant in order to have the deposit of uniform character and therefore some manual or automatic arrangement is used to tap the cathode gently at short intervals. I have found that the powder should be removed at least every 5 or 10 minutes by tapping the cathode.

.To remove the powder automatically, a clock, motor or other arrangement can be used, andI have diagrammatically illustrated one such form in the drawings. An electric motor 6 is geared through the requisite number of gears to a wheel 7 having a pin 8 which rises under a portion 9 of a tappet 10 and raises the latter to the position shown in dotted lines in the figure, where the in will clear the portion 9 and the tappet will spring downward under its own resilience to hit the cathode and remove the powder. This powder collects in a pile 11 at the bottom of the container and can be removed periodically in any manner.

,When the powder is fresh from the electrolyte it is in a very pure condition on account of the method of preparation, but if allowed to stand after washing out the copper sulfate solution, it will more or less change over into copper oxid. Drying in cacao, after washing out the copper sulfate solution, reduces this action, but it does not eliminate the difficulty to a sufficient extent to permit the powder to be used in making brushes. i

I have found that oxidation can be prevented by washing the powder with a liquid containing such materials as glucose, tannin, or other colloids, and thereby cause a precipitation of the colloids as a thin coating on the metal particles due to the action of the copper sulfate electrolyte. While glucose solution acts very satisfactorily, I prefer to use a tannin solution on account of its low cost. One way to carry out this step is to wash the powder fresh from the electrolyte in. a tea made by steeping maple, oak

or other sawdust in waterf *When the powder is washed in this solution the-tanning is molded under high pressure into the desired form. The molded article is then baked at a high temperature to cause the metal particles to adhere together and form a solid article. Brushes made in this way are strong and have good lubricating and conbut still higher current densities may he used.

The concentration of the electrolyte also plays an important part in the process. The

more concentrated the electrolyte, the coarser the powder is. l have found that a .8 normal solution of copper sulfate is the most satisfactory for obtaining the right quality of copper powder for, brushes, though different concentrations can be used, especially when articles other than 'metallic brushes are to be made from the powder,

As a further detail of the process I have found that it is advisable to arrange the apparatus so that the oxid, which is formed in small quantities at the anode, will not drop into and contaminate the copper powder. There are various ways of doing this, one of which is by placing a nonconducting partition 12 through the center of the lower part of the container, so that the copper powder will not settle under the anode in positionto be contaminated with the oxid. Another very efiicient way of solving the problem is to inclose the copper anode in a cloth envelop or screen 13 which will allow the electrolyte to readily percolate through naeaosa it, but which will prevent the oxid from falling to the bottom of the cell.

While T have described my invention with particular reference to the obtaining of copperpowder, it is nevertheless apparentithat .the process can be used in making other metal powders. For instance, I have formed zinc powder by electrolyzing zinc sulfate solution, iron powder by electrolyzing ferrous sulfate solution,

Having described my invention, what l claim is 1. The process of making metal powder, which consists in forming metal sponge in an electrolyte and placing the metal sponge ticles with a protective covering to prevent oxidation and then drying the coated particles.

3. The process of making a metal powder, which consists in electrolyzing a solution of a salt of the metal to form spongy metal on the cathode, removing the said metal, washing it free of electrolyte in a colloidal solution and then drying the metal powder.

4. The process of making a metal powder, which consists in electrolyzing a solution of a salt of the metal to form spongy metal on the cathode, removing the said metal, Washing it free of electrolyte in a colloidal solu tion and drying it in 'vacuo.

In testimony whereof, l hereunto afix my signature.

WILLIAM C, MOGRE.

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