US1835679A - Chromium plated article - Google Patents

Description

Dec. 8, 1931. c. VAN DERAU CHROMIUM PLATED ARTICLE Filed Jan. 5, 1929 N V E N TO R zrzzce %17 171 12- ATTORNEY Patented Dec. 8, 1931 UNITED STATES 'PATENT, "OFFICE CLARENCE VAN DEEAU, OF MANSFIELD, OHIO, ASSIGNOR 1'0 WESTINGHOUSE ELECTRIC &; MANUFACTURING- GOIMIPAITY,- A. CORPORATION OF PENNEY VANIA mom rm'rnn Application filed January'fi, 1929. Serial-Ho. 830,505.

My invention relates to' chromium-plated articles and more particularly to articles of this type having a foundation metal which magnbe easily cast into any desired form.

5 object of my invention is to provide a chromium-plated article having a foundation metal comprising lead or tin, or an alloy containing these metals, and a small amount of another metal,'such as antimony, in such.

proportions that the alloy may be cast into solid or tubular form.

Another object of m invention is to provide an article of manu acture having a foundation metal formed of an alloy, containing lead, tin and antimony, u on which is plated succe ssive layers of ca 'um, nickel and chromium. A further object of my invention is to provide a method of plating a'foundation metal,

containing a soft metalor alloy, with a protective layer of chromium, which comprises polishing the foundation metal, coating it with a metal that has a temperature coefiicient of expansion similar to the foundation metal, electrode ositin'g a layer of nickel on the coated foun ation metal to provide'a lustrous surface, and fi ially depositing an outer layer of chromium.

In plating comparatively soft metals with chromium, such as copper or brass, it is customary to polish the foundation metal and to coat it with a layer of nickel before the No. 76,119, filed and assigned to the Westinghouse Electric & Manufacturing Company.

In applying this method to a foundation metal composed of alloys containing either lead or tin, or both of these metals in combination with a small percentage of other metals, suchas copper or antimony, it was found that the nickel would not adhere to the foundation'metal during the subsequent chro-. mlum-plating operation.

In the bath utilized in the electrodeposition of chromium, which is maintained at a temperature of approximately 135 F. during the plating process, there'is a considera-- ble' evolution of gas which is caused princi- 6o pally by the decomposition of water. Nick e1 has a linear temperature coeflicient of expansion much less than that of tin or lead, or an alloy' containing these two metals, and it is believed that the scaling of the nickel coating during-the chromium-plating process is caused by the foundation metal expanding, under the influence of heat, to a greater extent than the nickelcoating. Undoubtedly, the evolution of gas alsohas the tendency 70 to preventan even deposition of chromium.

-I have made the discovery that'chromium can be successfully plated u'pon foundation metals containing lead, 131111.01 alloys of such metals, with a small percentage of antimony or copper, by first electrodepositing a layer of cadmium on-the foundation metal before applying the layer of nickel.

My method is particularly adapted in producing a good adherent layer of chromium on a foundation metal composed of an allo containing approximately to lea 29% to 39% tin and about 1% of antimony. It may also be applied with good results to a foundation metal composed of lead or tin alone, or to those alloys which are known in the art as Britannia metals and which are usually composed of tin, copper and antimony, although small proportions of zinc, lead and bismuth may be present. Such alloys are characterized by the fact that they may be easily cast into any desired form without shrinking, and any decorative emblems that are formed in the molds will be accurately reproduced on the molded metal. My invention will be better understood by reference to the accompanying drawings,

. in which,

Figure 1 is a side elevational view of a chromium-plated handle of a percolator having a foundation metal composed of a Britannia metal.

Fig. 2 is a similar view of the spout of a percolator having a foundation metal composed of the same alloy.

3 is a cross sectional view, on an enlargel scale, taken on the line IIII of Fig. 2 an Fig. 4. is a similar View, taken on the line 20 IVIV of Fig. 2.

In practicing my invention, the foundation metal is cast in a solid or in a tubular form, as shown in the drawings. It is then polished and a layer of cadmium is applied by an electroplating process. A layer of nickel is next deposited, which provides a smooth lustrous coating upon which the outer layer of chromium is plated.

I have found that, when the cadmium is adherent coating of-chromium will be produced. The coefficients of expansion per degree Fahrenheit of lead, tin and cadmium are .2940x10- .2257 10- and .3159 10-*, respectively, while that of nickel is .1397 X 10- 2- It will be noted that cadmium has a coefficient of expansion much more nearly like that of lead and tin than nickel. It is believed that this is the reason why cadmium will adhere to the foundation metal better than nickel. No difliculty, however, is encountered in producing an adherent layer of nickel upon the cadmium, even though their temperature coeflicients of linear expansion are considerably different.

The nickel serves as a backing for the chromium and provides a smooth surface upon which it may be plated. It has almost the same color and reflectivity as chromium and is especially desirable in the event that the chromium becomes thin or worn through.

While I have described a preferred embodiment of my invention, it will be understood that various modifications may be made therein without departing from the spirit of my invention. For example, if desired, the chromium may be deposited directly on the layer of cadmium. I prefer, however, to'utilize an intermediate coatingof nickel.

Other modifications of my invention will be apparent to those skilled in the art and I desire, therefore, that only such limitations shall be imposed thereon as are required by 65 the prior art-and the appended claims. I

first applied to the foundation metal, a more sesame I claim as my invention:

1. A chromium-plated article having a foundation metal comprising an alloy containing tin, an electrodeposited layer of cadmium on the foundation metal, an outer layer of chromium, and a layer of nickel interposed between the layer of cadmium and taining lead, tin and antimony, an electrodeposited layer of cadmium on the foundation metal, an outer layer of chromium, and a layer of nickel interposed between the layer of cadmium and the layer of chromium. I

4:. A chromium-plated article having a foundation metal comprising an alloy containing 60% to 70% lead, 29% to 39% tin and about 1% antimony, and successive layers of cadmium, nickel and chromium upon the foundtion metal.

5. The method of producing a chromiumplated article having a foundation metal of an alloy containing tin which comprises casting the foundation metal into any desired form, electrodepositing a layer of cadmium upon the cast foundation metal and then electrodepositing a layer of chromium upon the cadmium surface.

6. The method of producing a chromiumplated article having a foundation metal of an alloy containing tin, lead and antimony which comprises casting the foundation metal into any desired form and electrodepositing successive layers of cadmium, nickel and chromium upon the cast foundation metal.

7 The method of producing a chromiumplated article which comprises castin Britannia metal in any desired form, polishing its surface and electrodepositing thereon successive layers of cadmium, nickel and 1 chromium.

8. The method of producing a chromiumplated article which comprises casting a foundation metal composed of an alloy containing tin and antimony, plating the foundation metal with an intermediate metal having a coefiicient of expansion similar to the foundation metal and then electrodepositing successive layers of nickel and chromium upon the intermediate layer of metal.

9. A chromium-plated article having a foundation metal which may be readily cast into any desired form comprising an alloy containing tin, a layer of cadmium and an outer layer of chromium.

10. A chromium-plated article having a foundation metal comprising an alloy containing tin and lead which may be readil cast into any desired form, a layer of c mium and an outer layer of chromium.

11. A chromium-plated article comprising an alloy containing tin lead and antimon which may be readily cast into any desire form, a layer of cadmium and an outer layer of chromium.

In testimony whereof, I have hereunto subscribed my name this 4th day of December, 1928.

CLARENCE VAN DERAU.

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