JPS63315553A - Thermistor porcelain composition - Google Patents

Abstract

PURPOSE:To obtain the titled thermistor porcelain composition having small variability of resistance value and B constant and small change of resistance value with time, by adding a specific amount of Bi element as a secondary component to a main component consisting of Mn, Ni, Cu and Zr as metallic elements. CONSTITUTION:Raw materials such as manganese oxide, nickel oxide, copper oxide, zirconium oxide and bismuth oxide are blended in a ratio to give a porcelain composition having a composition comprising Mn, Ni, Cu and Zr as metallic elements as a main component and 0.1-10mol.% Bi element as a secondary component. Then the blend is calcined, ground, granulated, molded and sintered to give the aimed thermistor porcelain composition. The prepared thermistor porcelain composition is suitably used as a temperature detecting element and inrush current preventing element. The above-mentioned main component elements can be further blended with 0.1-10atom.% one or more elements of Li, B, Mg, Al, Si, Ti, V, Cr and Zn.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to an oxide thermistor containing Mn, Ni, Cu and Zr as main components, a so-called spinel thermistor, for detecting temperatures of -40 to 150'C or The present invention relates to a thermistor porcelain composition that has recently come to be used as a current protection element in many devices such as liquid thermometers and for protection of flicker sources.

Conventional technology Conventionally, Ko(7) seeds Mn -Ni -Cu -Zr
System thermistors have a widely used composition because the specific resistance and thermistor constant (B constant) can be controlled over a wide range by changing the ratio of each element, and it is easy to match with the circuit.

Problems to be Solved by the Invention However, this thermistor also has drawbacks in manufacturing, with large variations in characteristics (resistance value, B constant) during the completion process. This required aging treatment for about 3 to 7 days, but even this was not sufficient. Furthermore, the finished product changes significantly over time, making it difficult to manufacture highly accurate thermistors.

The cause of this is not clear, but it is thought to be caused by a complex interaction of scattering of elemental components during firing, stability of cation distribution, sintering reactivity, etc.

The present invention solves these problems, and is aimed at solving these problems.
Variations in the resistance value and B constant of thermistor ceramics whose main components are oxide solid solutions of Ni, Cu, and Zr (
The purpose is to provide a stable thermistor porcelain composition with a small coefficient of variation) and a small change in resistance value over time. The invention provides a thermistor ceramic composition as follows.

(1) A solid solution of Mn, Ni, Cu, and Zr oxides is the main component, and B1 oxide is added as a subcomponent.

(2) In the above structure, Li is further added as an elemental component to the main component.
, B, Mg, kl, Si, Ti
, 'i, Or.

One or more types of Zn are added.

Effect: Due to the above (1), variations in resistance value and B constant are reduced, and changes in resistance value over time are also significantly reduced. ′
Moreover, according to the above (2), the change over time can be further suppressed, and a highly accurate thermistor porcelain can be provided. Hereinafter, the present invention will be explained based on specific examples.

First, using commercially available manganese oxide, nickel oxide, steel oxide, zirconium oxide, bismuth oxide, etc., predetermined amounts were blended so as to have the composition shown in Table 1 below, and mixed for 20 hours using a bow mill.

After drying this at 150-250°C,
The calcined product was calcined at 00°C for 2 hours, and then ground in a ball mill for 20 hours, followed by drying. To this calcined powder, 10 parts of a p, v, mu (polyvinyl alcohol) solution having a concentration of 10 parts was added and mixed to perform granulation. Then, this granulated powder was pressure-molded into a disk shape with a diameter of 1011° and a thickness of 1.51B, and was heated at a temperature of 1000 to 1200'C.
After baking for an hour, a silver electrode was installed.

After leaving each disk-shaped thermistor element thus obtained at room temperature for one day, the specific resistance value was measured in an oil bath at 25°C and 50'C, and the B constant between these temperatures was calculated. . The results are shown in Table 2 below. In addition, these coefficients of variation are also listed at the same time. Further, each thermistor element was left in air at 150'C for 1000 hours, and the results of determining the resistance value change rate Rt (resistance value after time) are shown in the figure.

For comparison with the thermistor according to the present invention, a thermistor element made of a conventional composition was manufactured using the same method, and the resistance value, B constant, coefficient of variation thereof, and rate of change in resistance value were measured in the same manner and are also listed. did.

(Hereinafter referred to as Kinpaku) <Table 1> (US: conventional example) Table 2> Here, Li, Mg, B, added to the main components,
With regard to M1, etc., only one type or combination of two specific elements is described, but the present inventors have investigated L, B, Mg, Mul, Si, Ti.
.

It was confirmed that effects similar to those shown in Table 2 above can be obtained by adding a predetermined amount of one or more of the elements V, Or, and Zn.

Effects of the Invention As is clear from the above results, the thermistor according to the present invention has small variations in resistance value and B constant, is stable in manufacturing, and has small changes in resistance value over time. This can greatly contribute to the demand for higher precision.

In addition, in the present invention, if Bi oxide is less than 0.1 mol%, no effect on the coefficient of variation and aging of electrical properties is observed, and if it exceeds 10 mol%, the coefficient of variation becomes large. Therefore, it is excluded from the scope of the present invention. In addition, Li, Mg shown in the second claim
When the amount of added elements is less than 0.1 atomic width, the same effect as Bi oxide is not seen, whereas when it exceeds 10 atomic width, the coefficient of variation of electrical properties becomes large. It was out of range.

[Brief explanation of the drawing]

The figure shows the rate of change in resistance value over time of a thermistor element according to an embodiment of the present invention and a conventional thermistor element when left in air at 150'C.

Claims (2)

[Claims] (1) The main components are Mn, Ni, Cu, and Zr as metal elements, and 0.1 to 10 mol% of Bi element as a subcomponent.
A thermistor porcelain composition characterized by the following: (2) The main metal elements are Mn, Ni, Cu and Zr, with Li, B, Mg, Al, Si, Ti, V,
0.1 to 1 or more of Cr and Zn elements
1. A thermistor porcelain composition containing 10 atomic % of Bi element and 0.1 to 10 mol % of Bi element added as a subcomponent to these main components.