US1278744A - Alloy and method of purifying same. - Google Patents

Description

P. POETSCHKE.

ALLOY AND METHOD OF PURIFYING SAME.

APPLICATION FILED rm. 1, 191a.

1i %?8,7% v PatentedSept. 10,1918.

2 SHEETS-SHEET I.

Ql'lumargs P. POETSCHKE.

ALLOY AND METHOD OF PURIFYING SAME.

APPLICATION FILED FEB. 7, l9l8. LWSJWMD Patented Sept. 10,1918.

2 SHEETS-SHEET 2.

i M l aejwfe UNITED TATE PATENT OFFICE PAUL POE'ISCHKE, OF MILFORD, DELAWARE, ASSIGNOR TO L. D. GAULK COMPANY, OF MILFORD, DELAWARE, A CORPORATION OF DELAWARE.

ALLOY AND METHOD OF PURIFYING SAME.

Specification of Letters Patent.

Patented Sept. 10, 1918.

Application filed February 7, 1918. Serial No. 215,900.

-I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to alloys and a method of purifying the same, and particularly to dental alloys, and has for one object, the provision of a purified form of alloy for filling teeth.

Dental alloys consist of silver and tin with smaller amounts of other metals such as copper and zinc. Assold to dentists, they occur in comminuted form known as filings or shavings. For use, the comminuted alloy is amalgamated with mercury so as to yield a plastic mass capable of being condensed into a tooth cavity and hardenmg in sitw.

Dental alloys are manufactured by melting the various metals and casting the same in bars, which are then comminuted so as to secure the filings or shavings. The comminuted alloy is then annealed or heated for a certain time in order to improve its physical properties and adapt it to the practical requirements of the dentist.

In the process of cutting and annealing it, it is impossible to avoid tarnishing of the comminuted alloy, which takes place through the oxidation and sulfidation of the alloy, thereby causing the alloy to lose its bright luster, the accumulation forming impurities. These surface impurities also make it difiicult to amalgamate the alloy with mercury and the amalgam thus obtained isunclean. Moreover these impurities retard the setting of the amalgam.

To overcome these various defects, and provide an alloy which has a bright silvery appearance, in contrast to the alloys made by the usual methods and which have a dull or tarnished appearance, my present invention contemplates the manufacture of an alloy, in comminuted form, which is substantially free from surface oxidation and sulfidation, and the efiects generally known as tarnishing of the metal.

Therefore, with the above objects in view, and as clearly understood by those skilled in the art, the invention broadly consists in the method, and more definitely resides in removing the surface impurities or tarnish by immersing the comminuted and annealed alloy in a suitable solution, having a solvent action on the surface impurities but not in any way adversely affecting the quality of the alloy or altering its chemical composition, and after such immersion thoroughly washing the allow and drying the same.

Apparatus for practising the present method is illustrated diagrammatically in the accompanying drawing in which Figure 1 illustrates a form of tray; Fig. 2 is a perspective of the tray having a layer of the material to be treated; Fig. 3 is a sectional elevation of the container or vessel in which the trays containing the material are sub merged in the cleaning solution; Fig. 4 is a perspective view of a draining rack for supporting the trays, and Fig. 5 is an elevation partly in section of a drying device.

To secure the desired advantages and improvements in my alloy over comminuted alloys of ordinary manufacture, I employ a solution of acidified alcohol because such a solution accomplishes my purposes to better advantage than an aqueous solution of an acid; or of pure alcohol; or of a mixture of Water, acid, and alcohol. I may use ethyl alcohol, methyl alcohol, denatured alcohol, or a mixture thereof. As an acid of suitable character, I prefer to use hydrochloric acid. As a specific example I might mention denatured alcohol approximately 98 parts per volume and concentrated hydrochloricacid, approximately two parts by volume.

The alloy to be purified is spread out upon trays 2, having a permeable bottom 3 which will permit circulation of the liquid and without allowing an appreciable amount of alloy to pass through. I prefer to use a cloth of suitable texture stretched over a substantial wooden frame. The trays are then immersed in a-tank 4, preferably of stoneware, containing the solution described above and permitted to remain for from 18 to 24 hours or for such time as may be desired to clean the alloy. The trays are then removed from the solution, allowed to drain so as to remove the surplus solution, and then thoroughly washed in pure clean water in a tank.

The water is changed repeatedly until the final wash water is absolutely free from acid. The trays are placed upon a rack 5 and permitted to drain so as to remove the excess water, and in order to facilitate drying they are dipped inpure alcohol or other solvent which is miscible with water and has a lower boiling point. I may use ethyl, methyl, or denatured alcohol, or mixtures thereof, for this purpose. After the surplus alcohol has been allowed to drain off, the trays are placed in a drying chamber 6 having a heating coil or coils 7 and dried in a current of warm air which is freed from dust by filtering through a screen 8 therein. The velocity and temperature of the air is adjusted so as to dry the alloy as rapidly as possible. I prefer to use a rapid current of air at approximately 130 degrees F although this temperature may be varied depending upon the size and shape of the alloy particles. After the alloy is thoroughly dry it is transferred to convenient receptacles and is then ready to be packed in suitable containers for distribution.

What is claimed is:

1. The process of purifying comminuted alloys consisting in subjecting the comminuted alloy to treatment with acidified alcohol,washing in water, dehydrating with alcohol, and drying in a'curre'nt of warm air.

2. The process of purifying comminuted alloys consisting in subjecting the comminuted alloy contained in trays having a permeable bottom, to treatment with acidified alcohol, washing in water, dehydrating with alcohol, and drying in a current of warm air.

3. The process of purifying comminuted alloys consisting in subjecting the comminuted alloy to the treatment of acidified alcohol, washing in water, dehydrating with alcohol, and drying in a current of air. In testimony whereof I afiix my signature.

PAUL POETSCHKE.

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