US2343039A - Electrical resistance alloy - Google Patents

Description

? PatentedFeb. 29.1944 7 s PATENT OFFICE Y ELECTRICAL RESISTANCE ALLOY Victor 0. Allen, Madison. and Joseph F. Polak, Newark, N. .L, assignors to Wilbur B. Driver Company, Newark. N. 1.. a corporation of New Jersey No Drawing. animation July 9, 1942.

Serial No. 450,278... 4 C aims. '(01. 75-171) This invention relates to electrical resistance alloys and has for its object the provision of a chromium alloy fr'om'the normal value of .00014 ,ohm to a value as low as .00002, and will at the high resistance alloy having a relatively low temperature coefiicient of resistivity, particularly'in the range of temperatures below about 300 C.

Another objectis to provide an electrical resistance alloy suitable for use as a resistor element in electrical devices, apparatus and 'circuits.

Still another object is to provide an electrical resistance alloy consisting predominately of nickel and containing chromium to 30% in which the normal electrical resistance is mate-'- rially increased and the temperature coeflicient of resistivity is materially lowered without mate.- rial loss of hot and cold workability.

Other objects and advantages-will be apparent as the invention is more fully hereinafter disclosed.-- 1 V In accordance with these objects, we have discovered that copper and beryllium, in combination, are particularly eflective, in alloys of nickel and chromium, as agents for increasing the electricalresistance of the alloy and for lowering the temperature coefiicientof resistivity and that, in general, copper in amounts up to 3% and Be in total amounts up to 5%, but Cu and Be combined in total amount not over about 6% may be employed for tliis purpose without seriously impairing the normal hot and cold workability of the base nickel-chromium alloy.

As one specific embodiment of the present.in-, vention, but notas a limitation thereohthe adaptation of the same to a well known nickelchromium alloy containing'80% Ni and 20% Cr I heretofore employed asuan electric resistance alloy will be described.

The normal temperature coefficient of resistivity of anickel-chromium alloy containing 80% Ni and 20% Cr within-the temperature range I covered that. copper and beryllium additions tothis alloy in total amount not over about 6% tions to the alloy are made atthe expense of the I same time markedly increase the electrical resistance of the alloy 'at any temperature within the range 20' C.-300 C.

Ingeneral, the copper and beryllium .addi

nickel content of the alloy and maybe added in various percentages withim the'ranges above 7 given and in different relative proportions to obtain a' plurality of high resistance alloys of progressively lower temperature coefficients of resistivityand different electrical resistances.

A copper content much in excess of about 3% is undesirable for the reason that the hot workability of the alloy is detrimentally effected. A Be content of much over 5% is undesirable for the reason that both the hot and cold workcontaining 20% Cr, 2% Cu, .50% Be, balance Ni, in wire form, has an electrical resistanceof about 670 ohms percircular mil foot at20 C. andhas a-temperature coeificient of resistivity of about 9'I 10- (.000097).

"The austenitic structure and non-magnetic properties of this alloy together with its relatively high electrical resistance and low temperature coefficient of electrical resistance,

' adapts the alloy for extensive utility as instru- 4 ment' and radio resistors, shunts and similar devices.

We have found that larger amounts of Be in the alloy lower the electrical resistivity to a fur: ther extent and that Be about 4% with Cu about 2% gives the highest electrical'resistance with the lowest temperature coefiicient of resistivity.

' Due to the high cost of beryllium and the difwith copper not over about 3% and Be not over about 5%, .will efiectively, lower the temperature coefflcient of resistivity of the nickelficulty of producing and working the high Be content alloy; it is preferred to maintain a Be content of below 1% and a' cop er content of to 2.5% as this relative proportioning of the elements Be and Cu in the Cr.Ni base (Cr 1030%) appears to provide the best combination of the properties of electrical resistance'and temperature coefficient of resistivity at'the lowest cost.

In the manufacture of the Cr.Ni alloy containing Be and Gu ofthe present invention, the

Be and Cu, preferably in the form of a berylliumcopper alloy, is added to the molten CrzNi alloy after the molten CrNi alloy has been thoroughly deoxidized and degasifled by the usual deoxidizing and degasifying agents heretofore employed for this purpose and insofar as the term balance Ni is concerned as it may hereinafter appear in the claims, this term is to be construed as in- Whereas in the above specific embodiment an alloy containing Cr 20% is disclosed, it is believed apparent that the Cr may be varied within the range 10 to 30% with resultant increase and decrease in the Ni balance of the alloy, without essential departure from the present invention, obtaining thereby a variation in the electrical resistance and the specific temperature coefficient of resistivity of the alloy, the effect of the Be and Cu additions on any given Cr.Ni base alloy being substantially the same and equivalent to that indicated for the 80 Ni-20 Cr base alloy of the specific embodiment given, but of a different order.

It is believed apparent, from the above description of the present invention, that the same may be widely" varied without essential departure therefrom and all such are contemplated as may fall within the scope of the-following claims:-

What we claim is: I a 1. An electrical resistance alloy characterized by having a temperature coemcient of resistivity -below .00014 consisting of chromium 10 to 30%.

Be from small fractional percentages up to about 5%, Cu from small fractional percentages up to about 3%, with the total Be and Cunot over I about 6%, balance Ni.

2. An electrical resistance alloy characterized by having a temperature coefllcient of resistivity below .00014 consisting of chromium about 20%. Be from small fractional percentages up to about 5%, Cu from small fractional percentages up to about 3%, with the total Be and Cu not over about 6%, balance Ni.

3. An electricalresistance alloy characterized by having a temperature coefilcient of resistivity below .00014 consisting of Cr 20%, Be from small fractional percentages to 1%, Cu 1.5 to 2.5%, balance Ni.

4. Anelectrical resistance alloy characterized by havinga temperature coefllcient of about .00009'7 consistingof Cr 20%, Be .50% Cu 2%,