US3216955A - Electrical resistor - Google Patents
Electrical resistor Download PDFInfo
- Publication number
- US3216955A US3216955A US274904A US27490463A US3216955A US 3216955 A US3216955 A US 3216955A US 274904 A US274904 A US 274904A US 27490463 A US27490463 A US 27490463A US 3216955 A US3216955 A US 3216955A
- Authority
- US
- United States
- Prior art keywords
- molybdenum disilicide
- boron
- electrical resistor
- temperature
- electrical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- YXTPWUNVHCYOSP-UHFFFAOYSA-N bis($l^{2}-silanylidene)molybdenum Chemical compound [Si]=[Mo]=[Si] YXTPWUNVHCYOSP-UHFFFAOYSA-N 0.000 claims description 20
- 229910021343 molybdenum disilicide Inorganic materials 0.000 claims description 20
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 16
- 229910052796 boron Inorganic materials 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 150000004760 silicates Chemical class 0.000 description 3
- 229910011255 B2O3 Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 2
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- MMVYPOCJESWGTC-UHFFFAOYSA-N Molybdenum(2+) Chemical compound [Mo+2] MMVYPOCJESWGTC-UHFFFAOYSA-N 0.000 description 1
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000001066 destructive effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 239000000615 nonconductor Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000004663 powder metallurgy Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229910000679 solder Inorganic materials 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 1
- 229910001887 tin oxide Inorganic materials 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient
- H01C7/022—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient mainly consisting of non-metallic substances
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
- H01C7/001—Mass resistors
Definitions
- a general object of the invention is to provide a material suitable for use as an electrical resistor.
- molybdenum disilicide is a useful base material for electrical resistance elements.
- my Patent 3,006,865 I have described a refractory composition suitable for use as an electrical resistance element, comprising the reaction product of molybdenum disilicide and vanadium pentoxide.
- my pending US. patent application Serial No. 144,292 filed October 11, 1961, I describe an improvement upon the device covered by my aforementioned patent.
- the present invention has to do with a new composition, which for certain applications such as for electrical resistors, is an improvement over my patent and the pending patent application.
- molybdenum disilicide and bonding reacting agents such as the borides, silicates and oxides.
- the use of these materials affect the electrical conductivity of the molybdenum disilicide and the resultant products are in most cases unable to withstand thermal shock.
- a metal-like dense material is obtained, capable of sustained applications at high temperature, such as 1200 C., having good electrical conductivity and a positive resistance temperature coefiicient.
- the percent of boron added to the molybdenum disilicide determines the density of the combination, its resistivity and temperature coefiicient.
- the preferred range of boron is from 2% to 20%, the balance being molybdenum disilicide.
- the resistance material composition is prepared by ball milling the molybdenum disilicide and boron particles in a carbide lined mill for several hours. For a typical resistor element, I ball mill a mixture of 90% molybdenum disilicide and 10% boron. Rods .046" by 8.25", are pressed at 30 tons per square inch and have a pressed density of 3.75 cc.
- the grain size of the boron and molybdenum disilicide particles is 1.5 microns as measured with a Fisher sub-sieve sizer. After pressing, the rods are heated in a furnace for 30 minutes at 1100 C. When cool the rods are extremely hard and possess good tensile strength.
- Rods made with 5% boron added to 95% molybdenum disilicide are of a conductive refractory nature and have a resistivity of .0034 ohm cm. at 1200 C.; rods made with boron, balance molybdenum disilicide have a resistivity of .0041 ohm cm. at 1200 C., and .00168 ohm cm. at room temperature. Continuous operation in oxidizing atmospheres produces negligible change in resistivity, mechanical strength or appearance.
- terminals may be applied to the rods by a /2 nickel plating on each end.
- the plated ends may then be placed in a hollowed copper rod and the space between the rod and the hollow copper rod terminal filled with silver solder.
- This low resistance type contact "Ice is useful in resistors which are continuously operated over long periods of time and serve to maintain a low contact resistance.
- the copper rod contacts may be of sufficient mass to dissipate enough energy to keep the ends cool.
- the positive resistance temperature coefiicient characteristic of the resistor of this invention is important and keeps the current from progressively increasing to a destructive degree such as occurs with most semiconductors. If desirable, the positive temperature coefiicient may be reduced by the addition of tin oxide or other refractory conductive oxides possessing a negative resistance temperature coeificient.
- a resistor element To insure maxim-um electrical stability and density of a resistor element, it is heated prior to initial use, by an electric current discharged through it at a temperature beyond that at which the materials had been reacted. For example, a unit reacted at 1200" C. is heated to a temperature of about 1500 C. by discharging a current therethrough for a short time. This tends to equalize the resistance over the length of the unit.
- the resistivity of the composition may be increased by the addition of such refractory conductive materials as the nitrides, borides or carbides of Zr, Ti, Ta, Va or Cr; also by the addition of refractory non-conductors such as micronized aluminum oxide and the silicates and oxides of zirconium.
- refractory conductive materials as the nitrides, borides or carbides of Zr, Ti, Ta, Va or Cr; also by the addition of refractory non-conductors such as micronized aluminum oxide and the silicates and oxides of zirconium.
- compositions of this invention lend themselves to pressing into the desired shape prior to reaction, it is possible to produce circular resistor elements for use in rheostats or potentiometers, in place of wire wound types which tend to oxidize under overload or when operated at maximum rated capacity.
- An electrical resistor element consisting essentially of 2% to 20% boron, the balance being substantially all molybdenum disilicide, said resistor element being the product of heating a pressed mixture of boron and molybdenum disilicide particles in the desired proportion to a temperature of about 1100 to 1200 C. for a time sufficient to cause reaction of said particles in the mixture.
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Ceramic Engineering (AREA)
- Resistance Heating (AREA)
Description
United States Patent 3,216,955 ELECTRICAL RESISTOR Samuel Ruben, 52 Seacord Road, New Rochelle, N.Y. No Drawing. Filed Apr. 23, 1963, Ser. No. 274,904 2 Claims. (Cl. 252-512) This invention relates to a stable refractory electrically conductive element and specifically to an electrical resistor.
A general object of the invention is to provide a material suitable for use as an electrical resistor.
Other objects will be apparent from the disclosure.
In the past there has been a general recognition that molybdenum disilicide is a useful base material for electrical resistance elements. In my Patent 3,006,865 I have described a refractory composition suitable for use as an electrical resistance element, comprising the reaction product of molybdenum disilicide and vanadium pentoxide. In my pending US. patent application Serial No. 144,292, filed October 11, 1961, I describe an improvement upon the device covered by my aforementioned patent.
The present invention has to do with a new composition, which for certain applications such as for electrical resistors, is an improvement over my patent and the pending patent application.
I have found that the composition of molybdenum disilicide and elemental boron provides a superior resistance element.
The art discloses many combinations of molybdenum disilicide and bonding reacting agents such as the borides, silicates and oxides. The use of these materials affect the electrical conductivity of the molybdenum disilicide and the resultant products are in most cases unable to withstand thermal shock.
I have produced an improved electrical resistor element by mixing and grinding molybdenum disilicide granules :Wlth elemental boron and heating to a temperature in the order of 1100 C. to 1200 C. A metal-like dense material is obtained, capable of sustained applications at high temperature, such as 1200 C., having good electrical conductivity and a positive resistance temperature coefiicient.
The percent of boron added to the molybdenum disilicide determines the density of the combination, its resistivity and temperature coefiicient. The preferred range of boron is from 2% to 20%, the balance being molybdenum disilicide. The resistance material composition is prepared by ball milling the molybdenum disilicide and boron particles in a carbide lined mill for several hours. For a typical resistor element, I ball mill a mixture of 90% molybdenum disilicide and 10% boron. Rods .046" by 8.25", are pressed at 30 tons per square inch and have a pressed density of 3.75 cc. The grain size of the boron and molybdenum disilicide particles is 1.5 microns as measured with a Fisher sub-sieve sizer. After pressing, the rods are heated in a furnace for 30 minutes at 1100 C. When cool the rods are extremely hard and possess good tensile strength.
Rods made with 5% boron added to 95% molybdenum disilicide are of a conductive refractory nature and have a resistivity of .0034 ohm cm. at 1200 C.; rods made with boron, balance molybdenum disilicide have a resistivity of .0041 ohm cm. at 1200 C., and .00168 ohm cm. at room temperature. Continuous operation in oxidizing atmospheres produces negligible change in resistivity, mechanical strength or appearance.
If desired, terminals may be applied to the rods by a /2 nickel plating on each end. The plated ends may then be placed in a hollowed copper rod and the space between the rod and the hollow copper rod terminal filled with silver solder. This low resistance type contact "Ice is useful in resistors which are continuously operated over long periods of time and serve to maintain a low contact resistance. The copper rod contacts may be of sufficient mass to dissipate enough energy to keep the ends cool.
The positive resistance temperature coefiicient characteristic of the resistor of this invention is important and keeps the current from progressively increasing to a destructive degree such as occurs with most semiconductors. If desirable, the positive temperature coefiicient may be reduced by the addition of tin oxide or other refractory conductive oxides possessing a negative resistance temperature coeificient.
The particle size of the component elements, boron and molybdenum disilicide, influences the preferred mixture range in terms of resisitivity and mechanical properties at high temperature operation.
An important characteristic which I have observed is that when the boron and molybdenum disilicide are reacted and bonded together there is small dimensional change, in the order of 1% with the pressures presently utilized. This permits objects having mechanical strength at high temperature to be produced by powder metallurgy processes.
An examination of the structure of the reaction product indicates that the elemental boron combines with some of the molybdenum disilicide and also that a small amount of the boron oxidizes to boric oxide which combines with silicates formed during the heating period.
To insure maxim-um electrical stability and density of a resistor element, it is heated prior to initial use, by an electric current discharged through it at a temperature beyond that at which the materials had been reacted. For example, a unit reacted at 1200" C. is heated to a temperature of about 1500 C. by discharging a current therethrough for a short time. This tends to equalize the resistance over the length of the unit.
The resistivity of the composition may be increased by the addition of such refractory conductive materials as the nitrides, borides or carbides of Zr, Ti, Ta, Va or Cr; also by the addition of refractory non-conductors such as micronized aluminum oxide and the silicates and oxides of zirconium.
As the compositions of this invention lend themselves to pressing into the desired shape prior to reaction, it is possible to produce circular resistor elements for use in rheostats or potentiometers, in place of wire wound types which tend to oxidize under overload or when operated at maximum rated capacity.
I claim:
1. An electrical resistor element consisting essentially of 2% to 20% boron, the balance being substantially all molybdenum disilicide, said resistor element being the product of heating a pressed mixture of boron and molybdenum disilicide particles in the desired proportion to a temperature of about 1100 to 1200 C. for a time sufficient to cause reaction of said particles in the mixture.
2. An electrical resistor element as claimed in claim 1, which contains a small amount of boric oxide.
References Cited by the Examiner UNITED STATES PATENTS 3/49 McKinley 26457 5/56 Glaser 252518 XR OTHER REFERENCES Dummer: Fixed Resistors. Pitman & Sons (1956),
Claims (1)
1. AN ELECTRICAL RESISTOR ELEMENT CONSISTING ESSENTIALLY OF 2% TO 20% BORON, THE BALANCE BEING SUBSTANTIALLY ALL MOLYBDENUM DISILICIDE, SAID RESISTOR ELEMENT BEING THE PRODUCT OF HEATING A PRESSED MIXTURE OF BORON AND MOLYBDENUM DISILICIDE PARTICLES IN THE DESIRED PROPORTION TO A TEMPERATURE OF ABOUT 1100* TO 1200*C. FOR A TIME SUFFICIENT TO CAUSE REACTION OF SAID PARTICLES IN THE MIXTURE.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US274904A US3216955A (en) | 1963-04-23 | 1963-04-23 | Electrical resistor |
| GB10463/64A GB1036253A (en) | 1963-04-23 | 1964-03-12 | Electrical resistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US274904A US3216955A (en) | 1963-04-23 | 1963-04-23 | Electrical resistor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3216955A true US3216955A (en) | 1965-11-09 |
Family
ID=23050094
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US274904A Expired - Lifetime US3216955A (en) | 1963-04-23 | 1963-04-23 | Electrical resistor |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US3216955A (en) |
| GB (1) | GB1036253A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2463404A (en) * | 1945-03-02 | 1949-03-01 | Du Pont | Process for the production of boron articles |
| US2745928A (en) * | 1952-10-06 | 1956-05-15 | American Electro Metal Corp | Heater bodies and their production |
-
1963
- 1963-04-23 US US274904A patent/US3216955A/en not_active Expired - Lifetime
-
1964
- 1964-03-12 GB GB10463/64A patent/GB1036253A/en not_active Expired
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2463404A (en) * | 1945-03-02 | 1949-03-01 | Du Pont | Process for the production of boron articles |
| US2745928A (en) * | 1952-10-06 | 1956-05-15 | American Electro Metal Corp | Heater bodies and their production |
Also Published As
| Publication number | Publication date |
|---|---|
| GB1036253A (en) | 1966-07-20 |
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