US1926213A - Resistance wire - Google Patents

Description

Patented Sept. 12, 1933 UNITED STATES PATENT OFFICE RESISTANCE WIRE No Drawing. Application January 17, 1930 Serial No. 421,599

' 1 Claim.

This invention relates to an improvement in resistance wire for electric current and more particularly to resistance wire for use under the conditions and for the purposes where heretofore, for

5 example, platinum only has been found to give satisfactory results;

As is well known in connection with various uses a resistance wire is required, or desirable, which will have high electrical resistance and at 0 the same time a small thermic coeflicient of its resistance, and in many instances which will have high tensile strength and resistance to corrosion in the air. Heretofore the conditions outlined have been met partially by platinum and partially by constantan. Platinum has a high thermic coeflicient of resistance and apart from that its exceptionally high cost is a serious disadvantage. Constantan has the disadvantage of being rapidly corroded by the air.

Now it is the object of this invention to pro-' vide a resistance wire which will have desired high resistance; a small thermic coefficient of its resistance; exceptionally high tensile strength; will be resistant to corrosion in the air; capable of being readily soldered without corrosion to a support or terminal, which will be of relatively low cost and may be easily drawn and which will be adaptable for varous uses, with increased efliciency, in place of platinum or constantan as, for example, in Wheatstone bridges, and for similar purposes, and for the bridge wires in blasting caps, etc., etc.

In accordance with this invention I provide a resistance wire formed from an alloy of gold, which may be of any suitable purity and nickel in suitable proportions, the wire being drawn to a size, or cross sectional area, such that the resistance per unit of length will meet the requirements Lo of the particular use for which the wire is intended.

The resistance wire in accordance with this invention may desirably comprise an alloy composed of gold within about the range 5%-99% and nickel within about the range 95%-1% suitably melted together or alloyed in accordance with the usual practice in alloying metals and drawn into wire of any suitable size to give the resistance required per unit of length. While the re- ;o sistance wire embodying this invention may be composed of an alloy of gold and nickel within the broad range given, the proportions of gold and nickel will more desirably be within the narrower range of about 42%-75% gold and about $5 58%-25% nickel. For many purposes the wire may desirably be composed of about 58.4% gold and about 41.6% nickel.

As illustrative of, for example, resistance wire embodying this invention for use as bridge wire for blasting caps, the wire will desirably comprise an alloy containing say about 58.4% of gold, and 41.6% of nickel drawn to a size such that it will have a resistance of say about 360 ohms per yard. The proper length of wire is secured to the usual leg wires of an electric blasting cap by soldering, with an ordinary soldering iron, using, for example, a solder desirably containing about 67% tin and about 33% lead and using as a soldering flux either ordinary rosin or an ordinary soldering solution, as an aqueous solution of zinc chloride, ammonium chloride and hydrochloric acid. Such bridge wire will not be corroded by the soldering flux, and will efiiciently fire, the various compounds used for charging blasting caps.

For the various uses to which the resistance wire, in accordance with this invention and having the characteristics pointed out, may be put, the wire will be drawn to a size to provide resistance per unit of length desired, as will be obvious, and will be secured in place in any suitable manner.

It will be understood that the resistance wire in accordance with this invention may be comprised of gold, of various degrees of fineness, and, nickel in various proportions, it being understood that it is not the intention to limit this invention to the proportions of gold and nickel, or to the fineness of the gold indicated herein as desirable or preferable. It will be further understood that while the use of resistance wire embodying this invention has been illustrated more