CA1077351A - Resistance material and resistor made therefrom - Google Patents
Resistance material and resistor made therefromInfo
- Publication number
- CA1077351A CA1077351A CA256,794A CA256794A CA1077351A CA 1077351 A CA1077351 A CA 1077351A CA 256794 A CA256794 A CA 256794A CA 1077351 A CA1077351 A CA 1077351A
- Authority
- CA
- Canada
- Prior art keywords
- disilicide
- resistor
- vitreous enamel
- composition
- resistance
- 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
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
- H01C17/06—Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C17/00—Apparatus or processes specially adapted for manufacturing resistors
- H01C17/06—Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base
- H01C17/065—Apparatus or processes specially adapted for manufacturing resistors adapted for coating resistive material on a base by thick film techniques, e.g. serigraphy
- H01C17/06506—Precursor compositions therefor, e.g. pastes, inks, glass frits
- H01C17/06513—Precursor compositions therefor, e.g. pastes, inks, glass frits characterised by the resistive component
- H01C17/0656—Precursor compositions therefor, e.g. pastes, inks, glass frits characterised by the resistive component composed of silicides
-
- 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
Abstract
ABSTRACT
A vitreous enamel resistance material comprising a mixture of a vitreous glass frit and fine particles of a metal silicide of the transition elements of Groups IV, V
and VI of the periodic chart. The metal silicide may be of molybdenum disilicide (MoSi2), tungsten disilicide (WSi2), vanadium disilicide (VSi2), titanium disilicide (TiSi2), zirconium disilicide (ZrSi2), chronium disilicide (CrSi2) or titanium disilicide (TaSi2). The ingredients of the vitreous enamel resistance material are present in the proportion of, by weight, 25% to 90% glass frit and 75% to 10% metal silicide. An electrical resistor is made with the vitreous enamel resistor material of the present invention by coating a ceramic substrate with the vitreous enamel resistance material and firing the coated substrate at a temperature sufficient to melt the glass frit of the vitreous enamel resistance material. Upon cooling, the glass hardens so that the resultant resistor comprises the substrate having on the surface thereof a film of glass with the metal silicide particles embedded in and dispersed throughout the glass film.
A vitreous enamel resistance material comprising a mixture of a vitreous glass frit and fine particles of a metal silicide of the transition elements of Groups IV, V
and VI of the periodic chart. The metal silicide may be of molybdenum disilicide (MoSi2), tungsten disilicide (WSi2), vanadium disilicide (VSi2), titanium disilicide (TiSi2), zirconium disilicide (ZrSi2), chronium disilicide (CrSi2) or titanium disilicide (TaSi2). The ingredients of the vitreous enamel resistance material are present in the proportion of, by weight, 25% to 90% glass frit and 75% to 10% metal silicide. An electrical resistor is made with the vitreous enamel resistor material of the present invention by coating a ceramic substrate with the vitreous enamel resistance material and firing the coated substrate at a temperature sufficient to melt the glass frit of the vitreous enamel resistance material. Upon cooling, the glass hardens so that the resultant resistor comprises the substrate having on the surface thereof a film of glass with the metal silicide particles embedded in and dispersed throughout the glass film.
Description
73~
The lnvention relates to vitreous enamel resistance materials, resistors made -therefrom and the method of making the same.
BACKGROUND
A type of electrical resistance material which has recently come into commercial use is a vitreous enamel resistance material which comprises a mixture of a glass frit and finely divided particles of an electrical conductive material. The vitreous enamel resistance material is coated on the surface of a substrate of an electrical insulating material, usually a ceramic, and fired to melt the glass frit.
When cooled, there is provided a film of glass having the conductive particles dispersed therein. Terminations are connected tothe film to permit the resultant resistor to be connected in the desired circuit. -. -:
The materials which have been generally used for the conductive particles are the noble metals. Although the noble metals provide vitreous enamel resistance materials which have ~ -; satisfactory electrical characteristics, they have the dis~
advantage that they are expensive. Thus, the resistors made from the vitreous enamel resistance materials containing the noble metals are expensive to manufacture. Therefore, it would be desirable to have a vitreous enamal electrical resistance material which utilizes a relatively inexpensive conductive material so as to provide an electrical resistor which is relatively inexpensive to manufacture. In addition, the conductive material used must be capable of providing a -~resistance material having a wide range of resistance values and which is relatively stable over the entire range of the resistance values. By being stable it is meant that the resistance value of the resistance material does not change ~ .
. . ' .
~ ~'7~ ~S ~
or changes only a small amoun-t under operating conditions, particularly when subjected to changes in -temperature. The change in resistance value of an elec-trical resis-tor per degree change in temperature is referred to as -the "temperature coefficient of resistance" of the resistor. The closer the temperature coefficient of resistance is to zero, the more stable is the resistor with xespect to changes in temperature.
SUMMARY
It is an object of the present invention to provide a novel vitreous enamel resistance material utilizing a relatively inexpensive conductive material.
It is another object of the present invention to provide an electrical resistor utilizing a novel vitreous enamel resistance material.
It is a further object of the present invention to provide a vitreous enamel resistor having a relatively wide range of resistance values, which is relatively stable over the entire range of resistance values and which is relatively inexpensive to manufacture.
It is astill further object of the present invention to provide a vitreous enamel resistance material comprising a mixture of a glass frit and finely divided particles of a metal silicide selected from the group consisting of molybdemun ;
disilicide, tungsten disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide.
Other objects will appear hereinafter.
The invention accordingly comprises a composition of matter and product formed therewith possessing the characteristics, properties and relation of constituents which will be exemplified in the composition hereinafter described, and the scope of the invention will be indicated in the claims.
4 - , - . :
~3t7~3~1 More particularly, -there is provided an electrical resistor comprising a ceramic body containing on the surface thereof a coating of vitreous enamel resistor composition con-sisting essentially, of a borosilicate glass and, about 75% to 10% by weight of finely divided particles of a metal silicide selected from the group consisting of tungsten disilicide, moly-: bdemun disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide, mixed with its fired reaction products with said borosilicate glass, said composition being heated a-t a temperature sufficient to provide said reaction products.
: There is also provided an electrical resistor of the vitreous enamel type produced by preparing a vitreous enamel composition consisting essentially of a borosilicate glass frit and about 75 to 10% by weight of finely divided conductive particles of a metal silicide selected from the group consisting of tungsten disilicide, molybdenum disilicide, vanadium di-: silicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide; applying a uniform thick-ness of the composition to an insulating refractory substrate;
firing the coated substrate at a temperature of about 970C to 1150C at which the glass frit becomes molten and below the melting temperature of the conductive particles in a non-oxidizing atmosphere; cooling the resistor to form a glass matrix having the conductive particles dispersed therein; and connecting terminations to the vitreous enamel resistor com-position. , There is further provided the method of making an electrical resistor of the type wherein a vitreous enamel resistor composition is applied to a substrate comprising:
preparing a vitreous enamel resistor composition consisting 35~L
essentially of a borosilicate glass frit and about 75 to 10%
by weigh-t of finely divided conductive particles of a metal silicide selected from the group consisting of tungs-ten di-silicide, molybdenum disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide; applying a uniform thickness of the com-position to an insulating refractory substrate; firing the coated substrate at a temperature of about 970 to 1150C a-t which the glass frit becomes molten and below the melting temperature of the conductive particles in a non-oxidizing atmosphere; cooling the resistor to form a glass matrix having the conductive particles dispersed therein; and connecting terminations to the vitreous enamel resistor composition.
BRIEF DESCRIPTION OF DRAWING
The drawing is a cross-sectional view, on a highly exaggerated scale, of a resistor pxoduced in accordance with the present invention.
DESCRIPTION OF IN~ENTION
In general, the vitreous enamel resistance material of the present invention comprises a mixture of a vitreous glass frit and fine particles of a metal silicide of the transi-tion elements of Groups IV, V and VI of the periodic chart.
The metal silicide can be molybdenum disilicide (MoSi2), tungsten disilicide (WSi2), vanadium disilicide (VSi2), titanium disilicide (TiSi2), zirconium disilicide (ZrSi2), chromium di-silicide (CrSi2) or tantalum disilicide (TaSi2). More part-icularly, the vitreous enamel resistance material of the present invention comprises a mixture of a vitreous glass frit and a metal silicide of the above-stated group in the proportion of, by weight, 25% to 90% glass frit and 75% to 10% metal silicide.
:~7~
The glass frit used in the resistance material of the present invention may be oE any well~known composition which has a melting temperature below that of the refractory metal silicide. The glass Erits most preferably used are -the borosilicate frits, such as lead borosilicate frit, bismith, cadmium, barium, calcium or other alkaline earth borosilicate frits. The preparation of such glass frits is well known and consists, for example, in melting together the constituents of the glass in the form of the oxides of the constituents, and pouring such molten composition into water to form the frit.
The batch ingredients may, of course, be any compound that will yield the desired oxides under the usual conditions of frit production. For example, boric oxide will be obtained from boric acid, silicon dioxide will be produced from flint, barlum oxide will be produced from barium carbonate, etc.
The coarse frit is preferably milled in a ball-mill with water to reduce the particle size of the frit and to obtain a frit of substantially uniform size.
To make the resistance material of the present in-vention, the glass frit, and refràctory metal silicide are broken down, such as by ball-milling, to a substantially uni-form particle size. An average particle size of between 1 to
The lnvention relates to vitreous enamel resistance materials, resistors made -therefrom and the method of making the same.
BACKGROUND
A type of electrical resistance material which has recently come into commercial use is a vitreous enamel resistance material which comprises a mixture of a glass frit and finely divided particles of an electrical conductive material. The vitreous enamel resistance material is coated on the surface of a substrate of an electrical insulating material, usually a ceramic, and fired to melt the glass frit.
When cooled, there is provided a film of glass having the conductive particles dispersed therein. Terminations are connected tothe film to permit the resultant resistor to be connected in the desired circuit. -. -:
The materials which have been generally used for the conductive particles are the noble metals. Although the noble metals provide vitreous enamel resistance materials which have ~ -; satisfactory electrical characteristics, they have the dis~
advantage that they are expensive. Thus, the resistors made from the vitreous enamel resistance materials containing the noble metals are expensive to manufacture. Therefore, it would be desirable to have a vitreous enamal electrical resistance material which utilizes a relatively inexpensive conductive material so as to provide an electrical resistor which is relatively inexpensive to manufacture. In addition, the conductive material used must be capable of providing a -~resistance material having a wide range of resistance values and which is relatively stable over the entire range of the resistance values. By being stable it is meant that the resistance value of the resistance material does not change ~ .
. . ' .
~ ~'7~ ~S ~
or changes only a small amoun-t under operating conditions, particularly when subjected to changes in -temperature. The change in resistance value of an elec-trical resis-tor per degree change in temperature is referred to as -the "temperature coefficient of resistance" of the resistor. The closer the temperature coefficient of resistance is to zero, the more stable is the resistor with xespect to changes in temperature.
SUMMARY
It is an object of the present invention to provide a novel vitreous enamel resistance material utilizing a relatively inexpensive conductive material.
It is another object of the present invention to provide an electrical resistor utilizing a novel vitreous enamel resistance material.
It is a further object of the present invention to provide a vitreous enamel resistor having a relatively wide range of resistance values, which is relatively stable over the entire range of resistance values and which is relatively inexpensive to manufacture.
It is astill further object of the present invention to provide a vitreous enamel resistance material comprising a mixture of a glass frit and finely divided particles of a metal silicide selected from the group consisting of molybdemun ;
disilicide, tungsten disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide.
Other objects will appear hereinafter.
The invention accordingly comprises a composition of matter and product formed therewith possessing the characteristics, properties and relation of constituents which will be exemplified in the composition hereinafter described, and the scope of the invention will be indicated in the claims.
4 - , - . :
~3t7~3~1 More particularly, -there is provided an electrical resistor comprising a ceramic body containing on the surface thereof a coating of vitreous enamel resistor composition con-sisting essentially, of a borosilicate glass and, about 75% to 10% by weight of finely divided particles of a metal silicide selected from the group consisting of tungsten disilicide, moly-: bdemun disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide, mixed with its fired reaction products with said borosilicate glass, said composition being heated a-t a temperature sufficient to provide said reaction products.
: There is also provided an electrical resistor of the vitreous enamel type produced by preparing a vitreous enamel composition consisting essentially of a borosilicate glass frit and about 75 to 10% by weight of finely divided conductive particles of a metal silicide selected from the group consisting of tungsten disilicide, molybdenum disilicide, vanadium di-: silicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide; applying a uniform thick-ness of the composition to an insulating refractory substrate;
firing the coated substrate at a temperature of about 970C to 1150C at which the glass frit becomes molten and below the melting temperature of the conductive particles in a non-oxidizing atmosphere; cooling the resistor to form a glass matrix having the conductive particles dispersed therein; and connecting terminations to the vitreous enamel resistor com-position. , There is further provided the method of making an electrical resistor of the type wherein a vitreous enamel resistor composition is applied to a substrate comprising:
preparing a vitreous enamel resistor composition consisting 35~L
essentially of a borosilicate glass frit and about 75 to 10%
by weigh-t of finely divided conductive particles of a metal silicide selected from the group consisting of tungs-ten di-silicide, molybdenum disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide; applying a uniform thickness of the com-position to an insulating refractory substrate; firing the coated substrate at a temperature of about 970 to 1150C a-t which the glass frit becomes molten and below the melting temperature of the conductive particles in a non-oxidizing atmosphere; cooling the resistor to form a glass matrix having the conductive particles dispersed therein; and connecting terminations to the vitreous enamel resistor composition.
BRIEF DESCRIPTION OF DRAWING
The drawing is a cross-sectional view, on a highly exaggerated scale, of a resistor pxoduced in accordance with the present invention.
DESCRIPTION OF IN~ENTION
In general, the vitreous enamel resistance material of the present invention comprises a mixture of a vitreous glass frit and fine particles of a metal silicide of the transi-tion elements of Groups IV, V and VI of the periodic chart.
The metal silicide can be molybdenum disilicide (MoSi2), tungsten disilicide (WSi2), vanadium disilicide (VSi2), titanium disilicide (TiSi2), zirconium disilicide (ZrSi2), chromium di-silicide (CrSi2) or tantalum disilicide (TaSi2). More part-icularly, the vitreous enamel resistance material of the present invention comprises a mixture of a vitreous glass frit and a metal silicide of the above-stated group in the proportion of, by weight, 25% to 90% glass frit and 75% to 10% metal silicide.
:~7~
The glass frit used in the resistance material of the present invention may be oE any well~known composition which has a melting temperature below that of the refractory metal silicide. The glass Erits most preferably used are -the borosilicate frits, such as lead borosilicate frit, bismith, cadmium, barium, calcium or other alkaline earth borosilicate frits. The preparation of such glass frits is well known and consists, for example, in melting together the constituents of the glass in the form of the oxides of the constituents, and pouring such molten composition into water to form the frit.
The batch ingredients may, of course, be any compound that will yield the desired oxides under the usual conditions of frit production. For example, boric oxide will be obtained from boric acid, silicon dioxide will be produced from flint, barlum oxide will be produced from barium carbonate, etc.
The coarse frit is preferably milled in a ball-mill with water to reduce the particle size of the frit and to obtain a frit of substantially uniform size.
To make the resistance material of the present in-vention, the glass frit, and refràctory metal silicide are broken down, such as by ball-milling, to a substantially uni-form particle size. An average particle size of between 1 to
2 microns has been found to be preferable. The glass frit, and refractory metal silicide powder are thoroughly mixed together, such as by ball-milling in water or an organic medium, such as butyl carbitol acetate or a mixture of butyl carbitol acetate and toluol. The mixture is then ad~ustedto the proper viscosity for the desired manner of applying the resistance material to a substrate by either adding or removing the liquid medium of the material.
~t77~
To make a resistor with the resistance material of the present invention the resistance ma-terial is applied to a uniform thickness on the surface of a substrate. The sub-strate may be a body of any material which can withstand the firing temperature of the resistance material composition. The substrate is generally a body of a ceramic, such as glass, porcelain, refractory, barium titinate, or the like. The resistance material may be applied on the substrate by brushing, dipping, spraying or screen stencil application. The substrate with the resistance material coating is -then fired in a con-ventional furnace at a temperature at which the glass frit becomes molten. For resistance materials of the present in-vention containing any of the above-stated metal silicides except molybdenu~ disilicide, it has been found preferable to fire the coated substrate in an inert atmosphere, such as argon, helium, nitrogen or a mixture of nitrogen and hydrogen, to achieve a resistor of better stability. However, for a resistance material of the present invention in which the metal silicide is molybdenum disilicide, it has been found that firing the resistor in air provides a more stable resistor.
When the coated substrate is cooled, the vitreous enamel hardens to bond the resistance material to the substrate.
As shown in the drawing, the resultant resistor of the present invention is generally designated as 10. Resistor 10 comprises the ceramic substrate 12 having a layer 14 of the resistance material of the present invention coated and fixed thereon. The resistance material layer 14 comprises the glass 16 and the finely divided particles 18 of the metal silicide embedded within and dispersed throughout the glass 16.
.
A plurality of resistance materials of the present .:' ' ' ' : , ~a~7~3~
invention were made in which the conductive material was moly-bdenum disilicide in the various amounts shown in Table I and the glass Erit was a barium, titanium, aluminum borosilicate glass. Each of the resistance ma-terials was made by mixing together the glass frit and molybdenum disilicide particles in a ball-mill in butyl carbitol acetate. Resistors were made with each of the resistance materials by coating cylindrical ceramic bodies with the resistance material and firing the coated ceramic bodies in a conveyor furnace for approximately a thirty minute cycle, at a temperature and in an atmosphere as indicated in Table I. A number of resistors of each of the compositions were made, and the average resistance values and temperature coefficients of resistance of the resulting resistors of each group are shown in Table I.
TABLE I
Mblyb, Temper-denum ature Disil- And Resis- Temperatuxe Coef. of Resistance icide Fixing tance (% per C) 20(~ by wt.lAt~.osphexe(ohms~)+25C to 150C+25c to -55C
1020C-Air 1,900 +.0080 +.0053 1020C-Air 490 -+.0109 +.0094 1020C-Air 70 +.0217 +.0222 50- 970C-Air 6 +.1420 +.1465 970C-Air 25 +.1038 +.1038 1050C-N2 8,900 -.0214 -.0346 1100C-N2* 1,300 _.0066 -.0119 1020C-N2 500 +.0120 +.0066 970C-N2 5 +.1117 +.1166 970C-N2 4.3 +.1196 +.1222 ...... _ _ .. _ _ _ ~ .. _ _ .. . .
* Fixed on a 20 minute cycle.
EXAMPLE II
A plurality of resistance materials of the pxesent ~7'~S~
invention were made in which the conductive material was tungsten disilicide in the various amounts shown in Table II, and the glass frit was a barium, titanium, aluminum borosilicate glass.
Each of the resistance ma-terials was made in the same manner as the resistance materials of Example I, and resistors were made with each of the resistance materia]s in the same manner as described in Example I. The resistors were fired at 1050C
in the type of atmosphere indicated in Table II and the average resistance values and temperature coefficients of resistance for each group of the resultant resistors are indicated in Table II.
TABLE II
Tung-sten Disil- FiringResis- Temperature Coef. of Resistance icide Atmos-tance (% per C~
(% by wt.) phere(ohms/~) +25C to 150C +25DC-to -55C
11 Air5,000 +.1346+.0984 Air2,300 +.0547+.0810 Air600 +.0670+.0957 Air219 ~.1073+.1074 Air 75 +.1307+.1286 11 N2875,000 -.1010 -.1458 N22,500 -.0063 -.0077 N25~000 -.0025 -.0069 N22,000 +.0055-.0039 N21,500 +.0162+.0123 N2 36 +.0638+.0670 N2 21 +.0685+0.588 . . . _ _ _ A plurality of resistance ma-terials of the present invention were made in which the conductive material was -- lo _ 35~
zirconium disilicide in the various amounts shown in Table III
and the glass frit was a barium, titanium, aluminum borosilicate glass. Each of the resistance materials were made in the same manner as the resistance materials oE Example I, and resistors were made with each of ~he resistance materials in the same manner as described in Example I. The resistors were fired at 970C in the type of atmosphere indicated in Table III, and the average resistance values and temperature coefficients of resistance for each group of the resultant resistors are in-dicated in Table III.
TABLE III
ZirconiumFiringResis- Temperature Coef. of Resistance Disilicide Atmos- tance (% per C) (% by wt.) phere ohms/~)+25C to 150C +25C to -55C
lS N2 6,300 +.0021 +.0035 N2 475 +.0225 +.0232 N2 104 +.0262 +.0278 N2 44 +.0265 +.0277 Air 3,000 +.0130 +.0127 Air 610 +.0184 +.0178 Air 238 +.0285 +.0257 Air 112 +.0334 +.0344 E MPLE IV
Table IV shows the resistance values and temperature coefficients of resistance of a number of resistors of the present invention using resistance materials made from the various metal silicides indicated in Table IV in the indicated amounts with a barium, titanium borosilicate glass frit. The resistance materials were made in the same manner as the resistance materials of Example I and resistors were made with the resistance material in the same manner as described in t735~
Example I. The resistors were fired at approximately 1000C in a Nitrogen atmosphere.
T~BLE IV
Conduct- Tem~erature Coef. of Resistance ing % byResistance (~ per C) Material Weight(o ~,/O) +25C to 150C +25C to -55C
TiSi2 15 124 +.0163 -~.0161 TiSi2 25 63 +.0166 ~.0181 TiSi2 30 41 +.0143 +.0154 VSi2 20 1,300 +.0222 +.0108 VSi2 25 275 +.0298 ~.0355 VSi2 30 42 +.0411 _.0495 CrSi2 20 275 +.0184 +.0235 CrSi2 30 99 +.0568 +.0780 TaSi2 50 81 +.0319 +.0303 EXAMPLE V
A plurality of resistance materials of the present invention were made in which the conductive material was a metal silicide shown in Table V, and the glass frit was a barium, titanium borosilicate glass. Each of the resistance materials was made ln the same manner as the resistance material of Example I, and the resistors were made with each of the resistance materials in the same manner as described in Example I. The resistors were fired in a nitrogen atmosphere on a 30 minute cycle at a temperature as indicated in Table V
and the average resistance values and temperature coefficients of resistance for the resultant resistors are shown in Table V.
~L~t~t~
TABLE V
ConductingFiring Resis- Temperature Coe:E. of Resistance ~aterialTemper- tance (% per C) (% by vol.)ature(oh~s/~) +25C to 150C +25C to ~55C
WSi2 5% 1150C 9K -.0148 -.0220 l~bSi2 6% 1100C 925 +.0257 _.0215 MoSi2 8% 1100C 560 +.0327 +.0304 MbSi2 10% 1100C 413 +.0372 +.0360 W~i2 12% 1100C 269 +.0268 -~.02g7 WSi2 15% 1100C 179 +.0294 -~.0294 _ _ _ EXAMPLE VI
A plurality of resistance materials of the present invention were made in which 30% by weight of a silicide shown in Table VI, and 70% by weight of a barium, titanium, aluminum borosilicate frit were used. Each of the resistance materials was made in the same manner as the resistance mate-rials of Example I, and resistors were made with each of the resistance materials in the same manner as described in Example I. The resistors were fired in a nitrogen atmosphere on a 30 minute cycle at a temperature indicated in Table VI.
The average resistance values, temperature coefficients of resistance of the resistors, and the reaction products for the resultant resistor glazes are shown in Table VI. The reaction products for the resistor glazes were determined by analysis of detected X-ray diffraction patterns. The detected products ` are given in the order of decreasing strength of their dif-fraction pattern lines.
~7~3~
TA~E VI
Metal Firing Resis- Temperature Cbef. of Sili- Temper- tance ~esistance (~ per C) Reaction cide ature(ohms/d) +25C to 150C +25C to -55C Prcducts WSi2 1100ClK +.0206 +.0209 ~WB, WSi2 M~Si2 1100C13 +.1092 +.1010 M~Si2~
VSi2 1100C33 +.0931 +.1042 VSi2, BaSi205 CrSi2 1100C21 +.0960 +.1266 CrSi2, CrB2, BaSi205 TaSi 1100C Non- - -- TaSi2, Cond. TaB2, ~TaB
TaSi2 1150C* 80 +.0340 +.0187 TaSi2, TaB2, ~TaB
TiSi2 1100C 9 +.0464 +.0303 TiSi2, TiB2, BaSi203, TlC2 ZnSi2 1100C 9 +.0526 +.0485 ZrSi2, ZrB2 * 50% by weight of TaSi2 fired in nitrogen on a 20 minute cycle.
Analysis of the diffraction pattern data of the resistor glazes in Table VI, indicates that during the firing of the resistance material, the silicon of the metal silicide has a strong tendency to react with the glass. The remaining metal of the silicide then combines with boron from the glass to form a boride or with barium to form a mixed oxide. The conductors which are formed by firing the resistance materials, thus, in-clude both the metal silicides and their borides.
It shoulcl be understood that the examples of the resis-tors and resistance materials of the present invention shown in Tables I through VI are given merely to illustrate certain de-tails of the invention and are not to be ta~en as in any way limiting the invention thereto. The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, refer-ence should be made to the appending claims~ rather than to the foregoing specification as indicating the scope of the invention.
.
' ' ~ , .; '
~t77~
To make a resistor with the resistance material of the present invention the resistance ma-terial is applied to a uniform thickness on the surface of a substrate. The sub-strate may be a body of any material which can withstand the firing temperature of the resistance material composition. The substrate is generally a body of a ceramic, such as glass, porcelain, refractory, barium titinate, or the like. The resistance material may be applied on the substrate by brushing, dipping, spraying or screen stencil application. The substrate with the resistance material coating is -then fired in a con-ventional furnace at a temperature at which the glass frit becomes molten. For resistance materials of the present in-vention containing any of the above-stated metal silicides except molybdenu~ disilicide, it has been found preferable to fire the coated substrate in an inert atmosphere, such as argon, helium, nitrogen or a mixture of nitrogen and hydrogen, to achieve a resistor of better stability. However, for a resistance material of the present invention in which the metal silicide is molybdenum disilicide, it has been found that firing the resistor in air provides a more stable resistor.
When the coated substrate is cooled, the vitreous enamel hardens to bond the resistance material to the substrate.
As shown in the drawing, the resultant resistor of the present invention is generally designated as 10. Resistor 10 comprises the ceramic substrate 12 having a layer 14 of the resistance material of the present invention coated and fixed thereon. The resistance material layer 14 comprises the glass 16 and the finely divided particles 18 of the metal silicide embedded within and dispersed throughout the glass 16.
.
A plurality of resistance materials of the present .:' ' ' ' : , ~a~7~3~
invention were made in which the conductive material was moly-bdenum disilicide in the various amounts shown in Table I and the glass Erit was a barium, titanium, aluminum borosilicate glass. Each of the resistance ma-terials was made by mixing together the glass frit and molybdenum disilicide particles in a ball-mill in butyl carbitol acetate. Resistors were made with each of the resistance materials by coating cylindrical ceramic bodies with the resistance material and firing the coated ceramic bodies in a conveyor furnace for approximately a thirty minute cycle, at a temperature and in an atmosphere as indicated in Table I. A number of resistors of each of the compositions were made, and the average resistance values and temperature coefficients of resistance of the resulting resistors of each group are shown in Table I.
TABLE I
Mblyb, Temper-denum ature Disil- And Resis- Temperatuxe Coef. of Resistance icide Fixing tance (% per C) 20(~ by wt.lAt~.osphexe(ohms~)+25C to 150C+25c to -55C
1020C-Air 1,900 +.0080 +.0053 1020C-Air 490 -+.0109 +.0094 1020C-Air 70 +.0217 +.0222 50- 970C-Air 6 +.1420 +.1465 970C-Air 25 +.1038 +.1038 1050C-N2 8,900 -.0214 -.0346 1100C-N2* 1,300 _.0066 -.0119 1020C-N2 500 +.0120 +.0066 970C-N2 5 +.1117 +.1166 970C-N2 4.3 +.1196 +.1222 ...... _ _ .. _ _ _ ~ .. _ _ .. . .
* Fixed on a 20 minute cycle.
EXAMPLE II
A plurality of resistance materials of the pxesent ~7'~S~
invention were made in which the conductive material was tungsten disilicide in the various amounts shown in Table II, and the glass frit was a barium, titanium, aluminum borosilicate glass.
Each of the resistance ma-terials was made in the same manner as the resistance materials of Example I, and resistors were made with each of the resistance materia]s in the same manner as described in Example I. The resistors were fired at 1050C
in the type of atmosphere indicated in Table II and the average resistance values and temperature coefficients of resistance for each group of the resultant resistors are indicated in Table II.
TABLE II
Tung-sten Disil- FiringResis- Temperature Coef. of Resistance icide Atmos-tance (% per C~
(% by wt.) phere(ohms/~) +25C to 150C +25DC-to -55C
11 Air5,000 +.1346+.0984 Air2,300 +.0547+.0810 Air600 +.0670+.0957 Air219 ~.1073+.1074 Air 75 +.1307+.1286 11 N2875,000 -.1010 -.1458 N22,500 -.0063 -.0077 N25~000 -.0025 -.0069 N22,000 +.0055-.0039 N21,500 +.0162+.0123 N2 36 +.0638+.0670 N2 21 +.0685+0.588 . . . _ _ _ A plurality of resistance ma-terials of the present invention were made in which the conductive material was -- lo _ 35~
zirconium disilicide in the various amounts shown in Table III
and the glass frit was a barium, titanium, aluminum borosilicate glass. Each of the resistance materials were made in the same manner as the resistance materials oE Example I, and resistors were made with each of ~he resistance materials in the same manner as described in Example I. The resistors were fired at 970C in the type of atmosphere indicated in Table III, and the average resistance values and temperature coefficients of resistance for each group of the resultant resistors are in-dicated in Table III.
TABLE III
ZirconiumFiringResis- Temperature Coef. of Resistance Disilicide Atmos- tance (% per C) (% by wt.) phere ohms/~)+25C to 150C +25C to -55C
lS N2 6,300 +.0021 +.0035 N2 475 +.0225 +.0232 N2 104 +.0262 +.0278 N2 44 +.0265 +.0277 Air 3,000 +.0130 +.0127 Air 610 +.0184 +.0178 Air 238 +.0285 +.0257 Air 112 +.0334 +.0344 E MPLE IV
Table IV shows the resistance values and temperature coefficients of resistance of a number of resistors of the present invention using resistance materials made from the various metal silicides indicated in Table IV in the indicated amounts with a barium, titanium borosilicate glass frit. The resistance materials were made in the same manner as the resistance materials of Example I and resistors were made with the resistance material in the same manner as described in t735~
Example I. The resistors were fired at approximately 1000C in a Nitrogen atmosphere.
T~BLE IV
Conduct- Tem~erature Coef. of Resistance ing % byResistance (~ per C) Material Weight(o ~,/O) +25C to 150C +25C to -55C
TiSi2 15 124 +.0163 -~.0161 TiSi2 25 63 +.0166 ~.0181 TiSi2 30 41 +.0143 +.0154 VSi2 20 1,300 +.0222 +.0108 VSi2 25 275 +.0298 ~.0355 VSi2 30 42 +.0411 _.0495 CrSi2 20 275 +.0184 +.0235 CrSi2 30 99 +.0568 +.0780 TaSi2 50 81 +.0319 +.0303 EXAMPLE V
A plurality of resistance materials of the present invention were made in which the conductive material was a metal silicide shown in Table V, and the glass frit was a barium, titanium borosilicate glass. Each of the resistance materials was made ln the same manner as the resistance material of Example I, and the resistors were made with each of the resistance materials in the same manner as described in Example I. The resistors were fired in a nitrogen atmosphere on a 30 minute cycle at a temperature as indicated in Table V
and the average resistance values and temperature coefficients of resistance for the resultant resistors are shown in Table V.
~L~t~t~
TABLE V
ConductingFiring Resis- Temperature Coe:E. of Resistance ~aterialTemper- tance (% per C) (% by vol.)ature(oh~s/~) +25C to 150C +25C to ~55C
WSi2 5% 1150C 9K -.0148 -.0220 l~bSi2 6% 1100C 925 +.0257 _.0215 MoSi2 8% 1100C 560 +.0327 +.0304 MbSi2 10% 1100C 413 +.0372 +.0360 W~i2 12% 1100C 269 +.0268 -~.02g7 WSi2 15% 1100C 179 +.0294 -~.0294 _ _ _ EXAMPLE VI
A plurality of resistance materials of the present invention were made in which 30% by weight of a silicide shown in Table VI, and 70% by weight of a barium, titanium, aluminum borosilicate frit were used. Each of the resistance materials was made in the same manner as the resistance mate-rials of Example I, and resistors were made with each of the resistance materials in the same manner as described in Example I. The resistors were fired in a nitrogen atmosphere on a 30 minute cycle at a temperature indicated in Table VI.
The average resistance values, temperature coefficients of resistance of the resistors, and the reaction products for the resultant resistor glazes are shown in Table VI. The reaction products for the resistor glazes were determined by analysis of detected X-ray diffraction patterns. The detected products ` are given in the order of decreasing strength of their dif-fraction pattern lines.
~7~3~
TA~E VI
Metal Firing Resis- Temperature Cbef. of Sili- Temper- tance ~esistance (~ per C) Reaction cide ature(ohms/d) +25C to 150C +25C to -55C Prcducts WSi2 1100ClK +.0206 +.0209 ~WB, WSi2 M~Si2 1100C13 +.1092 +.1010 M~Si2~
VSi2 1100C33 +.0931 +.1042 VSi2, BaSi205 CrSi2 1100C21 +.0960 +.1266 CrSi2, CrB2, BaSi205 TaSi 1100C Non- - -- TaSi2, Cond. TaB2, ~TaB
TaSi2 1150C* 80 +.0340 +.0187 TaSi2, TaB2, ~TaB
TiSi2 1100C 9 +.0464 +.0303 TiSi2, TiB2, BaSi203, TlC2 ZnSi2 1100C 9 +.0526 +.0485 ZrSi2, ZrB2 * 50% by weight of TaSi2 fired in nitrogen on a 20 minute cycle.
Analysis of the diffraction pattern data of the resistor glazes in Table VI, indicates that during the firing of the resistance material, the silicon of the metal silicide has a strong tendency to react with the glass. The remaining metal of the silicide then combines with boron from the glass to form a boride or with barium to form a mixed oxide. The conductors which are formed by firing the resistance materials, thus, in-clude both the metal silicides and their borides.
It shoulcl be understood that the examples of the resis-tors and resistance materials of the present invention shown in Tables I through VI are given merely to illustrate certain de-tails of the invention and are not to be ta~en as in any way limiting the invention thereto. The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, refer-ence should be made to the appending claims~ rather than to the foregoing specification as indicating the scope of the invention.
.
' ' ~ , .; '
Claims (4)
OR PRIVILEGE IS CLAIMED, ARE DEFINED AS FOLLOWS:
1. An electrical resistor comprising a ceramic body containing on the surface thereof a coating of vitreous enamel resistor composition consisting essentially, of a borosilicate glass and, about 75% to 10% by weight of finely divided particles of a metal silicide selected from the group consisting of tungsten disilicide, molybdenum disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide, mixed with its fired reaction products with said borosilicate glass, said composition being heated at a temperature sufficient to provide said reaction products.
2. An electrical resistor of the vitreous enamel type produced by preparing a vitreous enamel composition consisting essentially of a borosilicate glass frit and about 75 to 10% by weight of finely divided conductive particles of a metal silicide selected from the group consisting of tungsten disilicide, molybdenum disilicide, vanadium disilicide, titanium disilicide, zirconium chromium disilicide and tantalum disilicide; applying a uniform thickness of the composition to an insulating refractory substrate; firing the coated substrate at a temperature of about 970°C to 1150°C at which the glass frit becomes molten and below the melting temperature of the conductive particles in a non-oxidizing atmosphere; cooling the resistor to form a glass matrix having the conductive particles dispersed therein; and connecting terminations to the vitreous enamel resistor composition.
3. The method of making an electrical resistor of the type wherein a vitreous enamel resistor composition is applied to a substrate comprising:
preparing a vitreous enamel resistor composition consist-ing essentially of a borosilicate glass frit and about 75 to 10% by weight of finely divided conductive particles of a metal silicide selected from the group consisting of tungsten disilicide, molybdenum disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide;
applying a uniform thickness of the composition to an insulating refractory substrate;
firing the coated substrate at a temperature of about 970° to 1150°C at which the glass frit becomes molten and below the melting temperature of the conductive particles in a non-oxidizing atmosphere;
cooling the resistor to form a glass matrix having the conductive particles dispersed therein; and connecting terminations to the vitreous enamel resistor composition.
preparing a vitreous enamel resistor composition consist-ing essentially of a borosilicate glass frit and about 75 to 10% by weight of finely divided conductive particles of a metal silicide selected from the group consisting of tungsten disilicide, molybdenum disilicide, vanadium disilicide, titanium disilicide, zirconium disilicide, chromium disilicide and tantalum disilicide;
applying a uniform thickness of the composition to an insulating refractory substrate;
firing the coated substrate at a temperature of about 970° to 1150°C at which the glass frit becomes molten and below the melting temperature of the conductive particles in a non-oxidizing atmosphere;
cooling the resistor to form a glass matrix having the conductive particles dispersed therein; and connecting terminations to the vitreous enamel resistor composition.
4. The method of Claim 3 in which the coated substrate is fired in a nitrogen atmosphere.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/673,303 US4039997A (en) | 1973-10-25 | 1976-04-02 | Resistance material and resistor made therefrom |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1077351A true CA1077351A (en) | 1980-05-13 |
Family
ID=24702100
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA256,794A Expired CA1077351A (en) | 1976-04-02 | 1976-07-12 | Resistance material and resistor made therefrom |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5931841B2 (en) |
| AU (1) | AU497489B2 (en) |
| CA (1) | CA1077351A (en) |
| DE (1) | DE2635699C3 (en) |
| DK (1) | DK143820C (en) |
| FR (1) | FR2346829A1 (en) |
| IT (1) | IT1071888B (en) |
| NL (1) | NL7608461A (en) |
| SE (1) | SE410773B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6131021A (en) * | 1984-07-25 | 1986-02-13 | 井関農機株式会社 | Grain tank support apparatus of combine |
| JPS6147257U (en) * | 1984-08-29 | 1986-03-29 | 株式会社クボタ | Combine grain collection device |
| JPS62253315A (en) * | 1986-04-24 | 1987-11-05 | セイレイ工業株式会社 | Grain tank support structure of combine |
| JP2532429B2 (en) * | 1987-01-20 | 1996-09-11 | 松下電器産業株式会社 | Glaze resistance material |
| WO2006102217A1 (en) * | 2005-03-21 | 2006-09-28 | Glass Coatings And Concepts Llc | Silicon alloys materials as silver migration inhibitors |
| GB0700079D0 (en) * | 2007-01-04 | 2007-02-07 | Boardman Jeffrey | A method of producing electrical resistance elements whihc have self-regulating power output characteristics by virtue of their configuration and the material |
| JP2019175608A (en) * | 2018-03-27 | 2019-10-10 | 株式会社デンソー | Electric resistor, honeycomb structure, and electric heating type catalyst device |
| JP7095544B2 (en) * | 2018-10-12 | 2022-07-05 | 株式会社デンソー | Electric resistors, honeycomb structures, and electrically heated catalysts |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3027332A (en) * | 1953-06-10 | 1962-03-27 | Kanthal Ab | Heat resisting materials and methods for their manufacture |
-
1976
- 1976-07-12 CA CA256,794A patent/CA1077351A/en not_active Expired
- 1976-07-12 SE SE7607961A patent/SE410773B/en not_active IP Right Cessation
- 1976-07-15 AU AU15920/76A patent/AU497489B2/en not_active Expired
- 1976-07-30 NL NL7608461A patent/NL7608461A/en not_active Application Discontinuation
- 1976-08-05 FR FR7623987A patent/FR2346829A1/en active Granted
- 1976-08-07 DE DE19762635699 patent/DE2635699C3/en not_active Expired
- 1976-09-10 JP JP51107983A patent/JPS5931841B2/en not_active Expired
- 1976-09-10 DK DK408776A patent/DK143820C/en not_active IP Right Cessation
-
1977
- 1977-01-05 IT IT8360177A patent/IT1071888B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| IT1071888B (en) | 1985-04-10 |
| SE7607961L (en) | 1977-10-03 |
| DK143820C (en) | 1982-03-29 |
| DK143820B (en) | 1981-10-12 |
| AU497489B2 (en) | 1978-12-14 |
| DE2635699A1 (en) | 1977-10-06 |
| AU1592076A (en) | 1978-01-19 |
| DE2635699C3 (en) | 1980-07-24 |
| JPS52120397A (en) | 1977-10-08 |
| JPS5931841B2 (en) | 1984-08-04 |
| FR2346829A1 (en) | 1977-10-28 |
| SE410773B (en) | 1979-10-29 |
| NL7608461A (en) | 1977-10-04 |
| FR2346829B1 (en) | 1982-02-19 |
| DK408776A (en) | 1977-10-03 |
| DE2635699B2 (en) | 1979-10-31 |
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