US2019687A - Alloy - Google Patents

Description

oxidation at high t'emperatures is essential. The

Patented Nov. 1935 v ALLOY James Lohr, Morristowm'N. 1., assignor to Driver-Harris Company, Harrison, N. J'., a corporation of New Jersey No Drawing. Applicationggne 1 1935;

Serial No. 26,

3 Claims.

This invention relates to alloys and more particularly to alloys for electrical resistance In the manufacture of electrical resistance units, an alloy having the propertyof resisting j alloys forming the subject matter of my inven tion are characterized by the ability to resist oxidation' and by a prolonged lite, exceeding that of other known alloys, when used under high temperature conditions. I Y

While nickel-chromium and nickel-chromiumiron alloys having the ability to resist oxidation at high'temperatures are known, their period of usefulness in service is often not as long as desired. 1' have found that the addition or small quantities or calcium and zirconium to such nickel-chromium alloys greatly increases their' period of life when. employed under conditions:

where they are subjected to high temperatures. The alloys forming the subject matter of the present application may also contain small quantitles of either silicon or manganese orboth of these elements.

In carrying out my invention I add small quantities oi calcium and zirconium, with or without silicon or manganese to nickel-chromium or nickel-chromium-iron alloys. The nickel-chromium alloy most generally used in'the art consists of 80 parts of nickel and 20 parts of chromium and I find it advantageous to add the other metals mentioned above to nickel-chromium alloys of substantially these proportions. The proportions of nickel and chromium in the alloy may be varied, Thus the chromium content may be from 15 to 25 percent and the balance nickel.

Likewise the most generally used proportions of nickel, chromium and iron in nickel-chrornium-iron alloys is 60 percent nickel, to percent chromium and the balance iron and I find it advantageous in many cases to employ substantially these proportions of those ingredients. adding the calcium and zirconium. These v proportions may also be varied, the nickel, however, forming the major part of the alloy, and the nickel-chromium content being such that the alloy will have .the characteristics of a nonierrous alloy. g

I may employ i'rom 7 to 22 percent chromium, 8 to 30 percent iron and the balance nickel.

In preparing alloys containing the additional elements enumerated, the quantities oi the additional elements are subtracted from the iron content, as for example, when calcium and zirconium are added to analloy containing 60 per- (cits-1) g a cent nickel, 10 1.6.15 percent chromium andi'the.

balance iron, the final alloy-will contain: 60 percent nickel, 10 to 15 percent chromium, calcium and zirconium in the percentages herein stated and the'balance iron.. The proportions oi calcium and zirconium may vary. withinflcertainlimits, I have found that. best results are obtained when these metals are present in the nickel-chromium .or'nickel-ohromium-iron alloy within the iollowinglimits:

- i et t Calcium 01 Zirconium .-01. 50

' It manganese or silicon are employed, they 15 may be used within the following Percent Manganese 0. 02-2. 0 8 a m-ac 20 "The preferred proportions' oi" the alloying agents are as iollo'ws:

) Percent Calcium .L.. .03 Zirconium g 26 Manganese 0. 05-1.0

Silicon I v 0. 404.5 Nickel-chromium and nickel-chromium-iron alloys containing the above ingredients within 30 the proportions given have been found by tests to have a greatly increased period 01' liie when exposed to high temperatures; For the purpose of determining the life of such alloys at high temperatures I have tested them by the method '35 of test outlined in. Tentative Accelerated Life Test For Metallic Materials For Electrical Heating of the American Society For Testing Materials described in vol. 29 of the "Proceedings of the Thirty-Second Annual Meeting 01 the American 40 Society for Testing Materials" beginning on page 613. The method is substantially as follows:

A sample 01' the wireto be tested, free from kinks;- apprcximately twelve inches long and of about .025" diameter, .is mounted vertically on'45 the test board, the upper end being held; in position by means of a suitable binding post. A 10 gram weight is attached to the lower end 0! the specimen. A shortpiece oi wire is attached to the.

10 gram weight and projects downward into a cup .of mercury where it may move freely up and down. A rheostat and' an interrupter are connected in series withthe specimen to the power supply. The test is run on constant temperature at a standard temperature chosen for the alloy 'pli'shed by means of an interrupter.

. while the lifeto the burnout is known as total life-j Throughout the test the power is on two minutes and 05 two minutes. This is accom- In testing the alloys of my invention according to the above described method a reference sample composed of 80 percent nickel and 20 per cent chromium and no alloy additions having an approximate lite-of 90 hours was used. This value is considered as 100 per cent and the useful life'oi the samples tested is determined in corresponding percentage values. table-the results obtained with samples containing calcium and zirconium are given:

I time eases 's'e'sieis In the following ance nickel. I

i. It will be noted that the useful life of such samples is from 425 per cent to 515 per cent of the standard sample. The use 0! calcium and; zirconium, thereiore, greatly'increases the useful life of the alloy for electrical resistance purposes where the wire is exposed to high temperatures.

In the alloys reierred to herein small amounts of phosphorus and sulphur maybe present as impurities. The nickel may also contain about 1 per cent of cobalt. v

I claim: 1. A nickelechromium-iron alloy containing '7 to 22 per cent ohromium,'8 to 30 per cent iron, 0.1 to .20 per-cent calcium, .01 to .50 per cent zirconium, balancenickel.

2. A nickel-chromium-iron alloy containing 7 to 22 per cent chromium, 8 to 30 percent iron, substantially .03 per cent calcium, substantially .25 per cent zirconium, balance'nickel.

3'. A nickel-chromium-iron alloy containing 10 to 18 per cent chromium, 1'1 to 30 percent iron, .01 to .20 calcium, .01 to .50 per cent zirconium, bal- JAMES M. LOHR.

.6 I i Y r It is herebycer-tif ied that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, -second column, line 15, claim 1, for "0.2L" read .01; and that the said Letters Patent should'be read with this correction therein that th e same may-con form to *the record ."of. the case in the Patent Of'fice.

Signed and sealed thisfiothgiey-of June; A. D. 1956.

Henry Van Arsdab (Seal) Ac t in g Commissioner or, Pat-ente