JPS6025387B2 - Method for manufacturing barium titanate semiconductor porcelain - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing barium titanate-based semiconductor ceramics containing Pb.

An object of the present invention is to provide a method for manufacturing barium titanate-based semiconductor porcelain that prevents evaporation of Pb during firing, is homogeneous, has little variation in specific resistance, and has stable characteristics.

Generally, by adding rare elements such as Ce and Y or one or more of Sb, Bi, and Nb to barium titanate, barium titanate-based semiconductor porcelain having positive resistance temperature characteristics is produced. What you get is well known.

It is well known that this semiconductor ceramic composition exhibits positive resistance-temperature characteristics in a high temperature range of 12,000 or higher by replacing a portion of Ba with Pb.

Semiconductor ceramics having such a composition are widely used as so-called constant temperature heating elements. Also recently, especially 250
Practical use is progressing as a heating element that can be used in a higher temperature range of 0.00 or higher. However, this type of material requires firing at a high temperature of 1250 q○ or more, and in particular, in those in which the sides are replaced with Pb at 35 atomic % or more, evaporation of Pb○ occurs significantly, causing compositional deviation. The disadvantages were that the electrical characteristics deteriorated and stability was lacking. In order to improve this, attempts have been made to fire in a Pbo or neutral gas atmosphere, or to cover the entire molded body with powder having the same composition as the molded body to be fired, but in such cases , there are disadvantages such as poor resistance temperature characteristics,
It lacked practicality. The manufacturing method of the present invention solves the above-mentioned problems, and involves wet-mixing barium titanate-based semiconductor porcelain raw material powder containing Pb, drying and pre-mixing, wet-pulverizing, A part of the side surface of the molded body made by granulation and then pressure molding is in contact almost perpendicularly with the main surface of the Akatsuki compact laid on the flat bottom surface of the sheath, and the molded body is In a method for manufacturing barium titanate semiconductor porcelain in which a plurality of barium titanate semiconductor porcelains are arranged and fired so that their principal surfaces face each other, the group of molded bodies is placed in a concave portion of a first semi-cylindrical body and mutually arranged in the concave direction. After arranging the molded bodies side by side so that their main surfaces face each other, and surrounding the first semi-cylindrical sintered body with a second semi-cylindrical sintered body having relatively large inner and outer diameters. Then, after surrounding the second semi-cylindrical sintered body with a third semi-cylindrical sintered body having the same length as the inner wall and a relatively larger outer diameter, the third semi-cylindrical sintered body is finally surrounded by a flat plate-shaped sintered body. It is characterized in that the front and rear spaces of the third semi-cylindrical compact are sealed and fired, and the above-mentioned compact and the first, second and third compacts are
The semi-cylindrical sintered body and the flat plate-shaped sintered body have the same composition, and there are many through holes near the ends of both sides of the second and third semi-cylindrical sintered bodies. It has been set up.

Next, examples of the present invention will be described.

First, commercially available/industrial raw materials BaC03, Ti02, P, S
BaC using i02, Nb205, Mn(N03)2 as starting materials.

30,6 mol "Ti.

21 mol, Pb.

0.4 mol, Si.

22.4 mol%, Nb2QO. 11 mol%, Mn(N.

3) A mixture of 2 and Mn with a composition of 0.03 atomic % was wet mixed in a ball mill for 2 spots and dried, and then
Temporarily bran at 0℃ for 2 hours. Next, the temporary bran powder is wet-milled in a ball mill for 2 hours and dried. Add an appropriate amount of organic/vinyl to this, granulate it, mold it at a pressure of 1000k9/ground,
A disk with a diameter of 20 skins and a thickness of 3.5 walls is prepared. The disks 1q are arranged in a concave portion of the first semi-cylindrical body in a substantially perpendicular manner so that the principal surfaces of the disks face each other in the direction of the concave surface. Next, a second semi-cylindrical grilled mackerel body is placed over the first semi-cylindrical adjacent body. Next, a third semi-cylindrical bran body having the same length as the second semi-cylindrical sintered body and relatively larger inner and outer diameters is placed over the second semi-cylindrical sintered body.
In other words, the first semi-cylindrical compact body on which the molded body is placed is covered with the second and third semi-cylindrical compact bodies. Finally, the anteroposterior space is sealed with a flat plate-like umbilical cord.
It should be noted that the first, second, and third semi-cylindrical crystal bodies and flat bran feeder bodies used here all have the same composition as the molded body. Further, a large number of through holes are provided near both end portions of the side surfaces of the second and third semi-cylindrical burnt stripes. An example of the bookkeeping state at this time is shown in the drawing. In the figure, 1 is a molded body, 2 is a first semi-cylindrical compact, 3 is a second semi-cylindrical competitive body, and 4 is a third cylindrical sintered body. There are many through holes 3' near both ends of the side of the semi-cylindrical bran body.
, 4' are provided.

5 is a Zr02 particle, and 6 is a pod.

With this structure, the binder can be completely removed during firing due to the through-holes, and the evaporation of Pb is extremely minimal since only the through-holes are sealed and the rest is sealed. Since they are made of the same composition, there is a uniform atmosphere around the molded body, and air and heat can also be supplied through the through holes, allowing for uniform firing. With this arrangement method, 125
Semiconductor porcelain was produced by firing at 0qo for 1 hour.

All of the semiconductor porcelains obtained in this manner were uniformly ground without any color unevenness.

Ohmic electrodes were provided on both sides of this IN solid semiconductor ceramic, and the specific resistance at 25 oo was measured. the result,
It was 6.2×1 pi○・ky (average value of IN hardness). In addition, as a guideline for the variation in specific resistance, the sum of squares is S=i≧, (X
, 1×)2 (n=10) The result was 7.9×1 p, indicating that the resistivity had stable characteristics with little variation.

Comparative Example Semiconductor porcelain was produced by simply arranging the molded bodies of the above example on the flat bottom of the pod so that their main surfaces faced each other, covering the pod with a normal pod lid, and otherwise using the same method as in the example. did.

Some of the obtained semiconductor porcelains were discolored, some had pores on the surface, and lacked homogeneity. Further, the specific resistance of this semiconductor ceramic was measured in the same manner as in the example. As a result, the specific resistance was as high as 1.8 x 1 pm, and the sum of squares was 1.0 x 1, which was a rather large variation, which was poor in practical use. As is clear from the above results, in the conventional method, the evaporation of Pbo is significant, leading to non-uniformity of the semiconductor porcelain, and the variation in resistivity is large, making it impractical. It is highly homogeneous, has small variations in specific resistance, and has stable characteristics.

[Brief explanation of drawings]

The drawing is a sectional front view showing the arrangement of molded bodies when carrying out the manufacturing method of the present invention. DESCRIPTION OF SYMBOLS 1... Molded body, 2... First semi-cylindrical Akatsuki body, 3... Second semi-cylindrical striped body, 4...
...Third semi-cylindrical sintered body, 3', 4'...
・Through hole, 5...2 particles of Z, 6...
Goya.

Claims (1)

[Claims] 1 Pb-containing barium titanate-based semiconductor porcelain raw material powder is wet mixed, dried and calcined, wet-pulverized, dried, granulated, and then pressure-molded to produce a molded body. A plurality of titanium bodies are arranged and fired so that a part of the side surface of the molded body is in almost perpendicular contact with the main surface of the sintered body laid on the flat bottom surface of the sheath, and the main surfaces of the molded bodies are facing each other. In the method for manufacturing barium oxide semiconductor ceramics, the group of compacts is placed in a concave portion of a first semi-cylindrical sintered body having the same composition as the compact, and the main surfaces of the compacts face each other in the direction of the concave surface. After arranging the first semi-cylindrical sintered body side by side, a second half having the same composition as the molded body and having a relatively large inner diameter and outer diameter and a large number of through holes near the ends of both sides is formed. After being surrounded by the cylindrical sintered body, the molded body has the same length as the second semi-cylindrical sintered body, has a relatively large inner diameter and an outer diameter, and has a large number of through holes near the ends of both sides. After surrounding the molded body with a third semi-cylindrical sintered body having the same composition as the molded body, the space before and after the third semi-cylindrical sintered body is finally sealed with a flat plate-shaped sintered body having the same composition as the molded body. A method for producing barium titanate-based semiconductor porcelain, characterized by firing the barium titanate-based semiconductor porcelain.