US 811859 A
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A. L. MARSH.
ELECTRIC RESISTANCE ELEMENT. APPLICATION FILED MAR. 15, 1905.
PATENTED FEB. 6, 1906.
UNITED sTA s P ENT OFFICE.
ALBERT L. MARSH, or LAKE BLUFF, ILLINOIS, ASSIGNOR To THE HOSKINS COMPANY, ILLINOIS.
OF CHICAGO, ILLINOIS, A CORPORATION OF ELECTRIC RESISTANCE ELEMENT.
To all whom it may concerts.-
Be it known that I, ALBERT L. citizen of the United States,
lufi, in the county of Lake and State of Illinois, have invented a new and useful Improvement in Electric Resistance Elements, of. which the following is a specification.
My object is to provide, as an improved electric resistance material, a metal which has the property of being particularly low in electric conductivity, has a meltingoint exceeding that of pure copper, and may e drawn or otherwise shaped to form particularly durable, efficient, and desirab or filaments suitable for use in the various connections where electric sirable.
I have discovered that the metals of what is termed the chromium group, particularly when mixed with nickel, form an alloy having the properties of being very low. in electric cond dizable to MARSH, a residing at Lake resistances are dea ve gh degree, tough and sufficientlyduetile to permlt drawing or shapelectric resistances, ta
we b loy consisting of ninety per cent. nickel and,
ing it into wire or strip form to render it con-' vement for use as an electricresistance elementi" The chromium group herein referred to, asdefined, for example, in cry of Ohem'ist consists of the metallic ele 'ments of oup %o.. VI, (indicated by the even numbere series,) according to what is generally desi nated asMendelefis table. (See page 212, emsens Chemistry, fifth edition, Hen Holt & 00., New York 1898.) These meta s are chromium, moly denum, tun sten, and uranium. Any one of these meta s is suitable for my ous reasons I prefer to employ chromium. Uranium at the present time is so rare and expensive as to render its gfineral use for my purpose commerclally pro 'bitive. As the above metals possess characteristics in commen which adapt them to m purpose, any one of them may be employe though when alloyed with nickel or cobalt, for example, proportions may va to produce the best the necessary toughness and ity desirable for the particular purp ese in d. a I have found, for example,
that an alten per cent. mommercrally. pure may be drawn into a fine wire and producing a tough metal chromium annealed, a meltingle strips, strands,
uctivity, very infusible, non-oxi' Watts Dilation.
purpose, though for vari-.
g into consideration" degree, of ductil r Specification of Letters Patent. Application filed Inch .15, 1905- Serial No. 260,309;
Patented Feb. 6, 1906.
point exceeding that of pure copper and with an electric re istance approximating fifty times that of ure copper. Its temperature coefficient is particularly low, it does not become crystalline and brittle under heating and coolmg, it resists oxidation to a remark likewise keeps a polish under all atmospheric conditions, even where corrosive fumes are present. Any metal of the chromium group .possesses desirable qualities for electric resist ance material whether employed alone or alloyed with nickel or cobalt. At the present time I am of o inion that the most practical and desirable e ectric resistance material may be formed of an alloy of nickel and chromium in suitable proportion drawn into strips, strands, or filaments and annealed, In its broadest sense, however, my invention is not to be limited to an alloy of the last-named metals.
The accompanying drawing shows a rheo stat of a well-known type in which the coiled wires a are resistance elements formed of a metal alloy, consisting of less than fifty per cent. of'a metal of the chromium group and more than fifty per cent. of nickel or cobalt, or both. In practice I prefer, commercial reasons, to form the alloy of preferably less than twenty five per cent. chromium and more than seventy-five per cent. nickel. Variations in the relative proportions of the metals would affect more or "less able degree under vervhigh temperature, and
mainly for the variations in strength, durability, and resistivit of the alloy. It may be stated. for examp e, that a metal alloy consistin of fifteen pe cent. chromium cent. nickel drawn into a wire sixteen onethousandths of an inch in diameter has a resistance ap roximatin 2.3 ohms per foot.
As state before, eit or nickel or cobaltis suitable for m purpose when alloyed with a metal of the cliromium group in a proportion of more than fifty or both, and less t mium or the like.
per cent. nickel or cobalt, han fifty per cent. chro- Nickel and cobalt alloy readily with metals of the chromium group and resist oxidation to 0. hi h degree. Iron, on the other hand, is read y oxidizable and will not answer my purpose when alloyed with a metal of the chromium ere I mention in the claims a meta hav- .mg the properties of nickel or cobalt, I wish to roup.
ve per too designate only the metals nickel and cobalt, which have properties that are the same for my purpose, but which cannot bothbe classed under an single term of which I am aware.
What claim as new, and desire to secure by Letters Patent, is-
1. An electric resistance element composed of a metal alloy consistingof one of the metals of the chromium group, in the proportion of less than fifty per cent. of the element, and more than fifty per cent. of metal having the properties of nickel and cobalt.
2. An electric resistance element comprising a strip, strand or filament formed of an alloy of nickel and one of'the metals of the chromium group.
3. An electric resistance element comprising an annealed strip, strand or filament formed of an alloy of nickel and one of the metals of the chromium group.
4. An electric resistance element formed of a metal alloy consisting of nickel and chromium.
5. An electric resistance element formed of a metal alloy consisting of chromium in the proportion of less than fifty per cent. of the element and nickel in the proportion of more than fifty per cent. of the element.
ALBERT L. MARSH. 1n presence of J. ll. LANDns, J. ll. LEE.