JPH02305403A - PTC resistance element - Google Patents

Abstract

PURPOSE:To obtain a PTC element having high mechanical strength by a method wherein SiO2 is added to a PbTiO3 composition for sintering. CONSTITUTION:SiO2 is added to a PbTiO3 composition having resistance with positive temperature characteristics for sintering. At this time, the added SiO2 works as a binder linking PbTiO2 crystal grains, the bonding of the crystal grains is strengthened, and the mechanical strength of element is enhanced. The proper adding quantity of SiO2 is 0.05mol or more and less than 0.3mol against PTC composition 1. Mechanical strength can not be obtained less than 0.05mol, and the increment in resistance is small and practical PTC is hardly obtained when the mol is more than 0.3. As a result, a stabilized PTC element having strong mechanical strength can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a PTC resistance element having a positive temperature resistance characteristic (PTC) and a high temperature (Tc) at which its resistance suddenly changes.

BACKGROUND OF THE INVENTION A BaTi0*-based element is known as a conventional PTC resistance element. BaTi○ has a Tc of 120°C, but it is known that by adding Sr, Sn, and Zr as a Tc shifter, Tc can be moved to the lower temperature side, and by adding Pb, Tc can be moved to the higher temperature side. There is. PTC elements are currently used in temperature sensors, constant temperature heating elements, hot air heaters, demagnetizing elements,
It is used in many ways as an overcurrent prevention element, etc.

Problems to be Solved by the Invention There is a demand for the development of such a PTC resistance element having an even higher Tc. This means that by increasing Tc, the heat capacity increases and more heat can be extracted.
This is because the R device can be made smaller. Furthermore, it is possible to develop a new field as a high-temperature heat source, such as a device that efficiently processes exhaust gas by temporarily holding a catalyst in a high-temperature PTC. In order to satisfy the above demand, it has been considered to increase the amount of Pb substituted as the shifter, and it has become possible to obtain a PTC element with T c = about 300°C. Furthermore, by increasing the amount of Pb substitution, T
Although it has been considered to raise the temperature of c to a high temperature, it is currently not possible to obtain a mechanical strength that is practical.

The present invention aims to obtain a PTC element having a high Tc of 300°C or more and high mechanical strength.

Means for Solving the Problems In order to solve the above problems, the present invention attempts to obtain a PTC element with strong mechanical strength by adding 5hot to a PbTiO2 composition and sintering it.

Function: In the present invention, PT with strong mechanical strength is obtained by the following method.
A C resistance element can be obtained. That is, PbTi○
, SiO□ is added to the system composition, stirred and mixed, and after molding, sintering is performed. At this time, the added 5jOz is PbT
It is thought that it acts as a binder that connects iOs-based crystal grains, strengthens the bond between the crystal grains, and increases the mechanical strength of the device.

EXAMPLE An example of the present invention will be described below. The general formula of the PTC composition used in the present invention is (P bl-f' A
M) T i C1+ (0≦X≦0.5) where,
A is a shifter agent and is at least one of Ca, Sr, and Ba. When x=0, that is, when PbTtOs, T
c is about 490'C, and as X increases, Tc
shifts to the lower temperature side. The mixing amount of A and Tc depend on the type of A.
Although the relationship with
, x = 0.1, Tc is approximately 400°C. X is 0
．． When the value is greater than 5, unstable PTC characteristics become apparent although the reason is not clear.The above is the outline of the PTC composition.

In the present invention, after adding Sing to this PTC ceramic composition and molding it, the
It was sintered at 0'c for 1 to 5 hours. The amount of 5iOz added is preferably 0.05 mol or more and 0.3 mol or less per 1 mol of the PTC composition. If it is less than 0.05 mol, the mechanical strength will not be sufficient (<, the effect of addition will not be obtained sufficiently, and if it is more than 0.3 mol, the increase in resistance will be small and it will be difficult to obtain a practical PTC.

Hereinafter, as a specific example (P b, , S ro,
+) Tie, the manufacturing method will be described. PbO, SrCox, and TiO2 were stoichiometrically calculated as raw material powders, and Nb2O5 was added as a semiconductor agent.
was added in an amount of 0.6 mol%. These raw material powders were thoroughly mixed and stirred in a wet manner, dried, and further calcined in air at 600°C for 3 hours. Thereafter, it was crushed to obtain a calcined powder.

0.1 mol of SiO□ was added to the calcined powder having the above composition and mixed and stirred. After this, 1050"C2 in an argon atmosphere
After time sintering, a PTC resistance element was obtained. This PTC resistance element had sufficiently strong mechanical strength to be put to practical use. Note that the resistance-temperature characteristic of this PTC resistance element is shown in the figure.

In the above example, (P bo, q S r o, +)T
Although we have described the case where SiO□ was added after calcination of iOx, similar characteristics were obtained even if SiO was added before calcination, although the variation in characteristics between devices increased.

Effects of the Invention As described above, the PTC resistance element of the present invention provides the following effects.

That is, in the present invention, since SiO□ is added and sintered, Sing acts as a binder between crystals, making the sintered body strong in mechanical strength, and at the same time creating stable PT.
A C element can be obtained.

[Brief explanation of drawings]

The figure is a diagram showing the temperature characteristics of the PTC resistance element of the present invention.

Claims (2)

[Claims] (1) A PTC resistance element made by adding SiO_2 to a PbTiO_3-based composition having positive resistance temperature characteristics and sintering it. (2) SiO
The PTC resistance element according to claim (1), characterized in that _2 is added in an amount of 0.05 to 0.3 moles and sintered.