US1246165A

US1246165A - Electrical-resistance material.

Info

Publication number: US1246165A
Application number: US83892314A
Authority: US
Inventors: Charles Ruzicka
Original assignee: Individual
Current assignee: Individual
Priority date: 1914-05-16
Filing date: 1914-05-16
Publication date: 1917-11-13
Anticipated expiration: 1934-11-13

Description

UNITED STATES PATENT OFFICE.

' CHARLES RUZICKA, 0F GRAVESEND, ENGLAND.

ELECTRICAL-RESISTANCE MATERIAL.

No Drawing.

To all whom it may concern:

Be it known that I, CHARLES RUzIexA, a subject of the Emperor of Austria, and resident of 9 Woodville Terrace, Gravesend, in the county of Kent, England, analytical and electro chemist, have invented certam new and useful Improvements in Electrical- Resistance Materials, of which the following is a specification.

This invention relates to electrical resistance materials made from a comminuted carbid-containing. mixture whose essential ingredients have been bound together into a homogeneous mass.

The object of the invention is to provide a hard, compact material having a high melting point which may be repeatedly raised to a high temperature without detriment to its physical or electrical properties.

According to my invention the resistance material is made from a mixture in the comminuted or pulverulent form of, on the one hand, a carbid of a metal or a carbid of a metalloid (or carbids of a metal or metals or carbids of a metalloid or metalloids), such metal or metals, metalloid or metalloids, having a comparatively high specific electrical resistance and a melting point above 1500 degrees centigrade; and on the other hand, of a carbid of a metal (or carbids of a-metal or metals), such metal or metals having a relatively lower specific electrical'resistance and a melting point not above 1500 degrees centigrade and not below 800 degrees centigrade.

Carbids of the first class above mentioned may bedescribed as a compound of carbon and an element, said element having a melting point over 1500 degrees centigrade, and in speaking of such carbids or compounds in the specification andclaims, I refer specifically to carbids of titanium, chromium,

tungsten, molybdenum, boron or silicon.

Carbids of the second class above mentioned may be described as a compound of carbon and an element, said element having a melting point not above 1500 degrees centigrade and not below 800 degrees centigrade, and in speaking of such carbids in the specification and claims, I refer specifically to carbids of manganese, iron, nickel or cobalt. To a mixture of these carbids there may be added, in the course of manufacturing the resistancematerial, (either forthe purpose of more effectively binding the individual particles of the carbids or of increasing the Specification of Letters Patent.

Patented Nov. 13, 1917.

Application filed May 16, 1914. Serial No. 838,923.

specific electrical resistance of the product, or of both binding together the individual particles and increasing the electrical resistance) a permanent substance having a melting point below that of any of the said carbids (e. 9. neutral feldspar, calcium silicate, iron silicate, or aluminium'borate or a mixture thereof also in the comminuted or pulverulent form) and which is neutral in respect of the other substances employed and a conductor of the second class. Furthermore, there may be added to the mixture of the carbids in the course of manufacturing the resistance material (with or without the addition of the neutral permanent substance) a temporary binding agent (such as a distilled dense mineral oil, glycerin, distilled mineral jelly) which is neutral and inert with respect to all the other ingredients and of such a nature that it will volatilize or burn away during or prior to the heating process, leaving to all intents and purposes no residue capable of modifying the specific electrical resistance of the product obtained.

The carbids employed may be either full carbids or carbids of a higher or lower degree than the full carbid. In any case care should be taken that, as the presence of free or unbound carbon would have a detrimental effect upon the resistance material under working conditions, no free or unbound carbon, whether from the carbid employed or from any other source, shall be present in the product.

In carrying out my invention, a powdery mixture of carbids of the two classes above referred to ,(with or without the addition of the permanent inert substance and with or without the addition of a quantity of the temporary binding agent sufficient to bring the mixture to a damp powder or pasty mass) is molded under pressure to the form of a. stick, tube, pellet, button, washer, &c., and then, while surrounded by a neutral or reducing gas .or substance (6. g. water-gas, coal-gas, or plumbago in the pulverulent form) heated in an electric or other suitable furnace until the particles of the carbid or carbids of the metal or metals of lower melting point become reduced to the partially or fullymolten state and envelop, weld or fuse together the particles of carbid or carbids of metals or metalloids of higher melting point, thus producing. when the material has become cold, a hard, homogeneous mass possessing constant specific electrlcal resistance throughout.

The specific electrical resistance of the ma-- terial obtained may be varied between wide limits either by making a selection of the carbids and permanent binding substance or substances according to their specific electrical resistance or by varying the relative proportions of the carbids or of the permanent substance or both.

For example, a material containing only a small quantity of a carbid of a metal or a carbid of a metalloid of high melting point and high specific resistance and a relatively large amount of carbid of a metal of low melting point and low specific resistance would possess lower specific electrical resistance than a material containing a greater proportion of the carbid of a metal or a carbid of a metalloid of high melting point and high specific resistance.

In making a resistance material for use in electric motor starters trollers, the following proportions adopted suitable or conmay be Boron carbid 6 parts by weight.

Iron carbid 2 parts by weight. Neutral feldspari parts by weight. Glycerin ..1 part by weight.

What I claim is 1. An electrical resistance material comprising a partially fused mixture of a com-. pound of carbon and an element, said element having a melting point greater than 1500 C. and of a second compound of carbon and an element, said element having a melting point between 1500 C. and 800 C.

2. An electrical resistance material comprising a partially fused mixture of a compound of carbon and an element, said element having a meltin point greater than 1500 C. and of a second compound of carbon and an element, said element having a melting point between 1500 C. and 800 C. the former material having a high specific resistance and the latter material a relatively lower specific resistance.

3. An electrical resistance material comprising a partiall fused mixture of two compounds each 0 carbon with an element, said elements having respectively a high specific resistance with a melting point above 1500 C. and a relatively lower specific resistance with a melting point between 1500 C. and 800 C. and a third permanent inert substance which is neutral to each of the aforesaid compounds and has a melting point less than that of either of them.

4:. An electrical resistance material comprising a mixture of boron carbid, iron carbid and neutral feldspar.

CHARLES RUZICKA.

Witnesses:

HERBERT D. J AMESON, WILLIAM E. Rooms.