DE1952838C - Ceramic body as a voltage-dependent resistor - Google Patents

Description

3 4

however, have a relatively low / i value and from 94.0 to 99.8 mole percent zinc oxide, 0.1 to 3.0

are fired in a non-oxidizing mole percent uranium oxide and 0.1 to 3.0 mole percent

Atmosphere produced, so that in particular a bismuth oxide. With such a ceramic body can

lower C-value is achieved. a low C value combined with a high one

From British patent specification 731 372, the USA. 5 η value can be obtained.

Patent specification 2 887 632 and the German patent The ceramic body of the invention can with advantage writing 618 803 ceramic resistance masses are also known essentially from 82.0 to 99.9 mol percent of zinc oxide and additions of other oxides. Zinc oxide, 0.05 to 10.0 mole percent uranium oxide and said British patent refer to 0.05 to 8.0 mole percent calcium oxide. A ceramic element of a low voltage io such ceramic body is against the Umziindsystems and a semiconductor resistor, the ambient temperature resistant and has a verjcdoch no non-ohmic properties. improved service life under electrical load. In addition, according to a special embodiment of the pre-British patent specification, the ceramic element contains a compressed ceramic body of the invention, as described, mixed base material of a refractory and 15, the ceramic body can consist essentially of 94.0 to insulating material and a layer of 99.8 mole percent Zinc oxide, 0.1 to 3.0 mol percent calcined mixture of metal oxides, the zinc oxide uranium oxide and 0.1 to 3.0 mol percent calcium oxide ir-, r! other oxides from groups Ib exist. A ceramic body assembled in this way contains! Vb, VlIb and VIII of the Periodic Table. exhibits a very improved stock ^; However, the mixture does not contain uranium oxide 20 ambient temperature as well as en.m very improved

U.S. Patent 2,887,632 relates to electrical load life.

^ Materials composed mainly of zinc oxide The ceramic body of the invention can also

and have a low specific resistance, advantageously also essentially from 82.0 to 99.9 mol

as well as a process for the production of these proze't zinc oxide, 0.05 to 10.0 mole percent uranium oxide

Materials. The materials described there consist of 25 and 0.05 to 8.0 mol percent cobalt oxide.

However, they have ohmic properties and contain. In such a ceramic body, the «value is

besides, no uranium. elevated.

The German patent 618 823 relates to a special Ausfühnuigsform of the above

Metal oxide resistor with a low temperature standing ceramic body of the invention described

coefficient and a specific resistance of 30, the ceramic body can essentially consist of 94.0

approximately 1 ohm-cm. This patent also contains up to .99.8 mol percent zinc oxide, 0.1 to 3.0 mol percent

writes only an ohmic and not a non-urar oxide and 0.1 to 3.0 mol percent cobalt oxide

Ehmian resistance. exist. A ceramic body assembled in this way

The aim of the invention is now to provide a ceramic body with an even further increased value. as a voltage-dependent resistor with non-35 The ceramic body of the invention can also To provide ohmic properties, also essentially from 74.0 to 99.83 mole percent in particular by a high η value based on zinc oxide, 0.05 to 10.0 mol percent Uianoxld, 0.05 to the ceramic body itself is made up of 8.0 mol percent bismuth oxide and 0.05 to 8.0 mol and, with regard to its C value, consists of one percent cobalt oxide. With one of these can be asked. 40 ceramic bodies can have a high / i-value together

This object is achieved according to the invention by one with a low C-value. Ceramic body of vorerreicht as voltage-dependent resistor According to a special embodiment, consisting essentially of 90.0 to 99.95 mol described Keramikkö ^r pers of the invention percent zinc oxide, and from 0.05 to 10.0 mole percent of uranium, the ceramic body consists essentially of 91.0 to oxide. Such a voltage-dependent resistor 45 99.7 mol percent zinc oxide, 0.1 to 3.0 mol percent stood has a non-ohmic resistance, the uranium oxide, 0.1 to 3.0 mol percent bismuth oxide and is due to the ceramic body itself. 0.1 to 3.0 mole percent cobalt oxide. Therefore, without the ceramic body thus composed, the C value of this resistor can be reduced, the C value deterioration of the value by changing the η value is decreased, and the η value is extremely increased. Distance between the opposing upper 50 The ceramic body of the invention can also be changed surfaces of the ceramic body. Finally, the shorter the distance, essentially from 74.0 to 99.85 mol, the lower the C value. percent zinc oxide, 0.05 to 10.0 mol percent uranium oxide,

According to one embodiment of the invention, 0.05 to 8.0 mol percent bismuthotide and 0.05 to the ceramic body consists essentially of 97.0 8.0 mole percent calcium oxide. This ceramic bis 99.9 mol percent zinc oxide and 0.1 to 3.0 molar body 55 have a high «value, a low one percent uranium oxide. With such a composite C-value and at the same time great durability. Ceramic body can receive a higher «value. ceramic body of the invention described above

According to a further embodiment of the invention, the ceramic body can essentially be made from 91.0

According to the invention, the ceramic body consists essentially of 60 to 99.7 mole percent zinc oxide, 0.1 to 3.0 mole percent

from 82.0 to 99.9 mole percent zinc oxide, 0.05 to uranium oxide, 0.1 to 3.0 mole percent bismuth oxide and

10.0 mole percent of uranium oxide and _0: 05 to 8.0 mole 0.1 to 3.0 Milprozent calcium oxide exist. The so percent bismuth oxide. In such a ceramic composite ceramic body, an extreme body of the present invention can have a high value, a low C value without change, and a large durability due to the size of the resistor and low.

the / i value can be reduced. These and other features of rounding are the

According to yet another embodiment of the following, more detailed description in the Vcr invention, the ceramic body is essentially linked to the drawing, which includes a ·. · ¹ I

952 will be. It is convenient to use a conductive adhesive, containing silver powder and resin in an organic solvent for connecting the lead wires to use with the electrodes.

The voltage-dependent resistors of the invention have a high resistance to temperature and to a load duration test which is carried out at 70 ^° C. for an operating time of 500 hours. The // value and

Currently preferred embodiments of the invention are explained below.

example 1

A mixture of zinc oxide and uranium oxide with a composition corresponding to Table 1 is mixed in a wet mill for 3 hours. The mixture is dried and calcined .EI long then for 1 hour '700 ⁰ C. The calcined Ciemisi.1i is pulverized in a motor-driven ceramic body within 30 minutes and then in a mold with a pressure of 500 kg / cm - to a shape with a diameter of 17.5 mm!

represents partial cross-section of a voltage dependent resistor of the invention.

Before the proposed according to the invention voltage-dependent resistors are described in detail are, their structure will be explained with reference to the drawing in which the number 10 denotes a voltage-dependent resistor as a whole, which is the effective element a ceramic sintered body with a pair

Contains electrodes 2 and 3, which change at its opposite io the C-value after the heating effects lying surfaces are attached. The sintered and the load duration are not noticeable. It is Ceramic body is based on one described below to achieve great resistance to Manner and possesses any- moisture advantageous when the obtained resistances Shape, e.g. B. a circular, square or stands with variable voltage in a moisture rectangle Plate shape. Lead wires 5 and 6 are 15 solid resin, such as. B. epoxy resin and phenolic resin /. are embedded with the electrodes 2 and 3 by a connection in a manner known per se, medium 4, such as B. a solder or the like., Conductively connected.

The sintered ceramic body 1 can be produced by a method known per se in the field of ceramics. The starting materials for the ceramic bodies described above are mixed in a wet mill to form homogeneous mixtures. The mixtures are dried and pressed together in a mold with a pressure of 100 to 1000 kg / cm ² to form the desired body shapes. The compressed bodies are sintered in the air at a given temperature for 1 to 3 hours

and then pressed together in the oven to room temperature (about 15 to 30 a thickness of 2.5 mm, about 30 ° C). E) he compressed body is in air when

"Sintered 135O ° C for 1 hour and then in the oven

cooled to room temperature (to about 15 to about 30 ° C). The sintered disc is attached to the opposite Surfaces ground with silicon carbide with a particle size of 600 mesh. The cm standcnc sintered disk has a size mm 14 mm in diameter and 1.5 mm in thickness. In the Commercially available electrodes made of silver paint;

For easier handling 40, the mixtures can be applied to the opposite surfaces of the sintered disk in the subsequent pressing process, first at 700 disk with the help of a paint. Then calcined to 1000 C and then powdered.
The mixture to be compressed
can with a suitable binder, such as. B. with
Water, polyvinyl alcohol, etc. are mixed.

It is advantageous if the sintered ceramic body on the opposite surfaces with Abrasive powder, such as B. with silicon carbide with a particle size of 300 to 1500 mesh, ground or is polished.

The sintered ceramic bodies are traced with electrodes on their opposite surfaces any applicable and suitable method, e.g. B. after electroplating, vacuum evaporation, Metallization, atomization or the silver painting process.

The voltage dependent properties are
practically not by the type of electrodes used, but by the thickness of the sintered body
influenced. In particular, the C value changes from 60 to 60
speaking of the thickness of the sintered grains while
the / i value is almost independent of the thickness. This
clearly shows that the voltage dependency; on the ceramic body itself and not on the.

Electrodes. 65 example /

Lead wires can be made in a known manner from 99.5 mol percent zinc oxide and 0.5 mol percent

and way using a conventional solder uranium oxide existing starting materials are in di with a low melting point attached in the manner described in Example 1 and Wei:

The appropriate finish is determined from the point of view the electrical specific resistance, the nonlinearity and the agility and ranges from 1000 to 1450 ° C.

The compressed bodies will be reduced when the electrical resistivity should, preferably in a non-oxidizing atmosphere, such as. B. in nitrogen and argon, sintered.

45 the lead wires are connected to the silver electrodes by soldering. The eic ', \ schcn properties of the resistances obtained are given in Table 1. It can be seen that the sintered body of zinc oxide containing uranium oxide in an amount of 0.05 to 10.0 mol percent is suitable for a voltage-dependent resistor. In particular, the addition of uranium oxide in an amount of 0.1 to 3.0 mol percent leads to an even more pronounced stress-nonlinear behavior.

Table 1

UO ₂ C. η UO ₂ C. η (MoI- (at (Mol (at percent) 1 mA) 3.1 percent) 1 mA) 3.9 0.05 25th 3.7 2 90 3.7 0.1 31 3.9 3 123 3.2 0.2 43 4.1 5 171 3.1 0.5 50 4.0 8th 220 3.0 1 65 10 340

mixed, dried, calcined and powdered. The powdered mixture is in a l-form / u one Frame 17.5 mm in diameter and 5 mm thick compressed with a pressure of 500 kg / cni-. The compressed body is sintered in LuTt at 135 ° C for one hour and then in the furnace cooled to room temperature. The sintered disk becomes one on the opposing surfaces Thickness given in Table 2. "Litteis silicon carbide ground with a particle size of 600 mesh. The ground disc is with the electrodes and the lead wires on the opposite one Provided surfaces in the manner indicated in the example I. The electric Values of the resistances obtained are given in Table 2: the C value changes approximately proportionally the thickness of the sintered disk, while the word is practically independent of the thickness. It is easy to see that the voltage is not linear Behavior of the resistances is to be ascribed to your sintered body itself.

labile 2

Thickness (mm) ((at I πιΛ) » Beginnings (4.0) 140 4.0 3.5 122 3.9 3.0 103 4.1 2.5 85 4.0 2.0 6S 4.1 1.5 50 4.0 1.0 35 3.9

15 e i s ρ i c 1 3

Made of zinc oxide with a content of uranium oxide and bismuth oxide corresponding to one given in Table 3 Voltage-dependent resistances according to the one described in Example 1 are used Procedure established. The properties achieved by the resistors are given in Table 3. It can easily be seen that the combination of uranium oxide and bismuth oxide added to lower C values without the; i-Wcrt changing to a correspondingly large extent.

Table 3

UO ₂
(Molpro / .ent)

0.05

0.05

0.05

0.5

0.5

10

H)

10
0.1
0.1
0.1
0.5
0.5
3
3
3
0.5

Hi ₅ O.,
(Mtilpro / .cnt)

0.05

0.5

0.05

0.05

0.5

0.1

0.5

0.1

.1

0.1

0.5

0.5

Example 4

C. 3.1 (at 1 niA) 3.1 16 3.0 7th 4.4 17th 4.2 35 3.1 36 3.0 220 3.1 70 4.0 215 4.1 16 4.0 7th 4.6 17th 4.4 25th 4.1 24 4.0 63 3.9 25th 4.6 65 11th

Made of zinc oxide with a content of uranium oxide and calcium oxide in a given in table 4 Voltage-dependent resistances according to the procedure specified in Example 1 are used manufactured. The resistances obtained are tested according to the methods used for electronic parts applied graze. The re!;; Sstungs: d.; Ucrnhe will at an ambient temperature of 70 C and at 0.5 watts within a service life of 500 hours. The heating repeat test is carried out by repeating a sequence in which the Mentioned resistors held at 85 ° C ambient temperature for 30 minutes, then quickly on Cooled to -20 ° C and kept at this temperature for 30 minutes. the Table 4 gives a difference for the C value and the // - Value of the resistances before and after your load duration test again. It can be seen easily that the combination of uranoxic and calcium oxide as an additive to the electrical duration liability and resistance to the order environment influences.

Table 4

UOi CaO Leave jngsil. -Wertest ; Jn (° / .l Periodic test warming (Mole percent) (Mole percent) .1 C- CU) '-7.3 ■: 1 C («/") i Λ η CU) 0.05 0.05 -8.4 -4.4 -8.2 ' -8.1 0.05 0.5 -4.6 '5.4 -5.9! -5.3 0.05 8th -6.1 ι -4.9 --7.7 ' -6.5 0.5 0.05 -5.5 ^: -3.3 -4.0 ^! -5.3 0.5 8th ' -4.8 i -6.4 -4.4 \ -5.4 10 0.05 -7.3 i -5.0 -7.5 -7.2 10 0.5 -5.4 ! -6.7 -6.1 -6.4 JO 8th -8.2 i -3.8 -8.5 0.1 0.1 -4.9 i -2.4 -3.9 ' --5.1 0.1 0.5 -4.0 i -2.4 -3.8! -3.7 0.1 3 -4.3 -2.0 -3.6 -4.5 0.5 0.1 -3.0 I - ^{1 9} -3.1 -3.5 0.5 3 -2.9 ! -2.3 -2.7 -3.1 3 0.1 -4.2 ; -2.0 -2.3 -5.0 3 0.5 -3.3 3.4 -4.7 -4.2 3 3 -4.9 1 -1.8 -4.8 0.5 0.5 -1.0 -1.9 -3.2 -5.3: -1.2

VN) ΑΠ7 / Τ

ίο

Example 5

Zinc oxide, which contains the additives given in Table 5, becomes voltage-dependent resistors produced according to the procedures described in Example I. The / r values of the obtained Resistances are given in Table 5. It's easy to see the combination of uranium oxide with cobalt oxide as an addition in a pronounced way to an extraordinarily sti '"' xen spinning nonlinear behavior leads.

Table 5

oxide as additives in a marked way to an excellent / i value and at the same time to a lower one C value leads.

UO, CoO C. ft (Mole percentage) (Mole percent ' (at 1 111Λ) 6.2 0.05 0.05 50 12th 0.05 0.5 50 6.0 0.05 8th 48 9.1 0.5 0.05 99 8.9 0.5 8th 102 6.1 10 0.05 620 13th 10 0.5 570 5.8 10 8th 585 12th 0.1 0.1 60 17th 0.1 0.5 61 12th 0.1 3 95 13th 0.5 o, t too 12th 0.5 1
J 95 11th 3 0.1 240 Ki 3 0.5 245 13th 3 3 250 18th 0.5 0.5 95

Table 6 UO ₂ CoO Bi, O, C. 6.3 (M'jlprozcnt) (Mole percent) (Mole percent) (at 1 inA) 6.0 0.05 0.05 0.05 35 6.1 0.05 0.05 8th 36 9.2 0.05 8th 0.05 32 5.9 0.05 8th 8th 70 6.1 10 0.05 0.05 400 6.1 10 0.05 8th 380 5.8 10 8th 0.05 390 13th 10 8th 8th 375 12th 0.1 0.1 0.1 30th 12th 0.1 0.1 3 32 11th 0.1 3 0.1 48 12th 0.1 3 3 50 11th 3 0.1 0.1 120 13th 3 0.1 3 110 12th 3 3 0.1 128 18th 3 3 3 123 0.5 0.5 0.5 19th

Example 6

From zinc oxide, which contains the additives indicated in Table 6, according to the method in Example I described method voltage-dependent resistors produced. The electrical properties of the The resistances obtained are shown in Table 6. It's easy to see the combination of uranium oxide and bismuth oxide with cobalt

Example 7

From zinc oxide, which contains the additives indicated in Table 7, according to the method in Example I described process sequence produced voltage-dependent contradictions. The resistances obtained are tested under the same conditions as in Example 4. Table 7 gives the initial C value and the differences in the C value and the / i value resulting from the values before and after Enter endurance test, again. It can be easily seen that when using the combination of uranium oxide, bismuth oxide and calcium oxide as In addition, the initial C-value of the resistance is decreased and that at the same time the resistance is excellent in electrical and environmental endurance tests.

Table. 7th

UO ₂ Bi ₂ O., CaO C. Load duration test Λ " CM Periodic heating test A η (»/") (Mole percent) (Mole percentage) (Mole percent) (at 1 mA) Δ C (· / ") -8.1 JCC / "1 -7.9 0.05 0.05 0.05 12th -3.2 -7.0 -8.0 -6.8 0.05 0.05 8th 13th -6.3 -6.4 -7.0 -6.3 0.05 8th 0.05 12th -4.9 -5.9 -6.3 -5.8 0.05 8th 8th 14th -3.7 -7.0 -5.0 -4.2 10 0.05 0.05 150 -5.1 -4.9 -4.2 -6.9 10 0.05 8th 140 -4.0 -5.0 ' -6.1 -5.9 10 8th 0.05 153 -4.2 -6.9 -8.1 -7.0 10 8th 8th 139 -7.9 -2.8 -8.1 -4.6 0.1 0.1 0.1 18th -4.2 -3.8 -4.6 -3.7 0.1 0.1 3 16 -3.9 -4.8 -4.7 -3.8 0.1 3 0.1 14th -4.9 -4.1. -4.9 -4.9 0.1 3 3 17th -4.1 -3.9 -5.0 -2.8 3 0.1 0.1 40 -3.3 -4.7 -4.9 -4.6 3 0.1 3 37 -4.2 -4.3 -3.8 -3.8 3 3 0.1 50 -3.7 -4.3 -3.7 -3.3 3 3 3 46 -3.5 -1.1 -4.1 -1.0 0.5 0.5 0.5 10 -0.8 -1.2

1 sheet of drawings

Claims (1)

I 952 than voltage dependent Patent claims: 1. Ceramic body as a voltage-dependent resistor, characterized in that that it consists essentially of 90.0 to 99.95 mole percent zinc oxide and 0.05 to 10.0 mole percent Uranium oxide consists. 2. Ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that it consists essentially of 97.0 to 99.9 mole percent zinc oxide and 0.1 to 3.0 mole percent Uranium oxide consists. 3. Ceramic body as a voltage-dependent resistor according to claim 1, characterized in that »5 records that it consists essentially of 82.0 to 99.9 mole percent zinc oxide, 0.05 to 10.0 mole percent Lran oxide and 0.05 to 8.0 mole percent bismuth oxide. 4. ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that he is essentially from 94.0 to 99.8 mole percent zinc oxide, 0.1 to 3.0 mole percent uranium oxide and 0.1 to 3.0 mole percent bismuth oxide consists. 5. Ceramic body as a voltage-dependent resistor according to claim 1, characterized in that d- ^ ß he essentially from 82.0 to 99.9 mole percent zinc oxide, 0.05 to 10.0 mole percent Uranium oxide and 0.1 to 8.0 mole percent calcium oxide. 6. ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that he is essentially from 94.0 to 99.8 mole percent zinc oxide, 0.1 to 3.0 mole percent uranium oxide and 0.1 to 3.0 mole percent calcium oxide consists. 7. ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that he is essentially from 82.0 to 99.9 mole percent zinc oxide, 0.05 to 10.0 mole percent uranium oxide and 0.05 to 8.0 mole percent Cobalt oxide. 8. ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that it consists essentially of 94.0 to 99.8 mole percent zinc oxide, 0.1 to 3.0 mole percent Uranium oxide and 0.1 to 3.0 mole percent cobalt oxide. 9. ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that it consists essentially of 94.0 to 99.8 mole percent zinc oxide, 0.1 to 3.0 mole percent Uranium oxide and 0.1 to 3.0 mole percent cobalt oxide. 10. ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that it consists essentially of 74.0 to 99.85 mole percent zinc oxide, 0.05 to 10.0 mole percent Uranium oxide, 0.05 to 8.0 mole percent bismuth oxide and 0.05 to 8.0 mole percent cobalt oxide consists. 11. Ceramic body as a voltage-dependent resistor according to claim 1, characterized in that that it consists essentially of 91.0 to 99.7 mole percent zinc oxide, 0.1 to 3.0 mole percent uranium oxide, 0.1 to 3.0 mole percent bismuth oxide and 0.1 to 3.0 mole percent cobalt oxide. S & 5saa £? Exid and 0.05 to 8.0 mole percent Calc.umox.d ^^ Ceramic body as a voltage-dependent Resistance according to claim 1. »VhnPt this essentially from 91.1) b, s 97 mole percent zinc oxide, 0.1 to 3.0 mole percent Uranium oxide 0.1 bL x 3.0 mole percent bismuth ox.d and 0.1 to 3.0 mole percent calcium ox.d. _The invention SS _{in the} ceramic body a, varistors that contain zinc oxide, with non-ohmic resistance that is applied to the ceramic body itself SSr ^ mun ^ dependent resistances, such as ζ B silicon carbide varistors, Selengle.chr.chter and Germanium or silicon p-n surface equivalents, S to a large extent to stabilize the Voltage or current of electrical circuits has been applied. The electrical characteristics Le such voltage-dependent resistance are given by the equation expressed in which V is the voltage across the resistor, Ϊ the current flowing through the resistor, C is a constant corresponding to the voltage at a given current, and the exponent «is a number greater than 1. The value for η is calculated according to the following equation: in which V ₁ and V _{% are} the voltages given by currents Z ₁ and I _2. The appropriate value for C depends on the type of application for which the resistor is to be used. It is generally advantageous if the value η is as large as possible because this exponent determines the extent to which the resistances deviate from the ohmic values. With common varistors, which consist of germanium or silicon p-n area rectifiers, it is difficult to adjust the C-value for a wide range because the stress-dependent property these varistors are not based on the ceramic body as such, but on the p-n junction, On the other hand, the silicon carbide varistors have a voltage dependence on the contacts between the individual grains of silicon carbide! is due to that by a ceramic bond means are interconnected, and the C-Who can by changing one dimension into one: Direction in which the current flows through the varistor can be set. The silicon carbide varistorei