JPS60186466A - Electroconductive ceramic material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a novel conductive ceramic material, more specifically, zirconia containing a predetermined amount of ittria and lanthanum chromate La□-XCaxOrOB (x = 0 to 0.4) having a specific composition.
The present invention relates to a ceramic material having electrical conductivity and excellent mechanical strength, which is made of a sintered body containing a predetermined proportion of .

In recent years, with rapid technological progress in fields such as mechatronics and electronics, the demands on ceramic materials as new materials are becoming increasingly diverse and sophisticated.

In particular, conductive ceramic materials have attracted attention because they have wear resistance, which is a characteristic of ceramic materials, and are effective in preventing static electricity that occurs during sliding.
It is used in home appliance parts such as guide rollers for TR. In order for such conductive ceramic materials to effectively exhibit antistatic properties, their specific resistance must be 106Ω°.
(b) or less, and it is desirable that the material has sufficient mechanical strength as a mechanical component like alumina porcelain.

Conventionally, as this type of conductive ceramic, titanium oxide or titanium composite oxide having semiconductivity has been used. However, these have a mechanical strength of at most 1500
It was about kg/cm2, υ, and was easy to wear due to its poor toughness, making it unsatisfactory as a material for mechanical parts.

In view of these circumstances, the present inventors have conducted intensive research to provide a conductive ceramic material that has excellent mechanical strength and good toughness. Tuchromic acid tan La
, -XOaXOr03 (x = o to o, 4) in a predetermined ratio was found to be suitable for the purpose, and based on this knowledge, the present invention was completed.

That is, the present invention (gradient) IJA 3 to 10
% and (B) compositional formula % formula % (1) (X in the formula is 0 to 0.4). Provided is a conductive ceramic material which is a sintered body made of lanthanum chromate, characterized in that the ratio of component (A) to component (B) is 6:7 to 7:3 based on weight. It is something to do.

The conductive ceramic material of the present invention is characterized by a composite containing lanthanum chromate or lanthanum chromate in which a part of the lanthanum ions are replaced with calcium ions in a predetermined ratio in zirconia containing a predetermined amount of ittria. This type of composite sintered body has its own characteristics because the zirconia particles form a strong matrix and the semiconductive oxide forms a conductive path in the matrix. It has electrical conductivity with a resistance of 10 6 Ω·m or less, and has high mechanical strength that is approximately twice the mechanical strength of conventional conductive ceramic materials.

In order to obtain a sintered body in which zirconia particles form a strong matrix, it is necessary to sinter at a high temperature of around 1600°C. It is necessary to use a material that does not have a significant adverse effect on the components, and the lanthanum chromate La□-xCaXCrO3 used in the third aspect of the present invention
(X-0 to 0.4) satisfies the above conditions.

The zirconia used as component (A) in the ceramic material of the present invention contains itria in a range of 6 to 10% by weight. The amount of ittria is 3% by weight
In the case of non-drip, cranks occur in the obtained sintered body,
On the other hand, if it exceeds 10 nia, the mechanical strength decreases.

In addition, (lanthanum chromate used as the Bl component or lanthanum chromate in which a part of the lanthanum ions are replaced with calcium ions) has the following composition formula (1)% formula % () (X in the formula is 0 to 0. 4).The amount of calcium ions replacing lanthanum ions is 1
If more than 0.4 mol of lanthanum chromate is used, the mechanical strength of the sintered body decreases.

In the ceramic material of the present invention, the ratio of the 4-(A) component zirconia to the (Bl component lanthanum chromate) must be within the range of 3 to 7:3 based on weight, When the amount of zirconia is less than 30 times the sum of both components, the mechanical strength decreases,
On the other hand, if it exceeds 70% by weight, the specific resistance will increase and the conductivity will become poor.

To give an example of the method for manufacturing the ceramic material of the present invention, first, predetermined amounts of lanthanum oxide, chromium oxide, calcium oxide, or compounds that can be converted into these oxides by firing are mixed using a mixer such as a ball mill. After thorough mixing, the mixture was heated to 1000-1400°C.
The powder is calcined at a temperature of 100 to obtain a chromate protein powder containing the desired calcium in advance.

On the other hand, after thoroughly mixing predetermined amounts of zirconium oxide and yttrium oxide, or compounds that can be converted into these oxides by firing, using a mixer such as a ball mill, this mixture is heated at a temperature of 1000 to 1400°C. Calcination is performed to obtain a desired ittria-containing zirconia powder. Next, this powder and the above-mentioned lanthanum chromate powder containing calcium are mixed in a predetermined ratio using a mixer such as a ball mill, and after drying, this mixed powder is mixed with a press binder and molded. 1500-170
Fire at a temperature range of 0°C.

In this case, instead of using zirconia powder containing ittria, each may be added as an independent powder, or it may be used as a composite oxide powder prepared by a known method such as a coprecipitation method or a colloid addition method. good.

The conductive ceramic of the present invention is a composite sintered material containing lanthanum chromate or lanthanum chromate in which a part of the lanthanum ions are replaced with calcium ions as a conductive path forming material in a strong zirconia matrix. Because it is a solid body, it has excellent mechanical strength and conductivity, as well as good toughness, and can be effectively used in many fields as a new material that can withstand even particularly harsh conditions.

Furthermore, as a secondary effect, the ceramic material of the present invention has
Since it is non-magnetic and has a large coefficient of thermal expansion of approximately 9 x 10 = /'Q, when used in combination with metallic materials,
For example, it is also effective for electronics substrates.

Next, the present invention will be explained in more detail with reference to Examples.

The strength was determined by a known six-point bending test method, and the specific resistance was measured at room temperature using an insulation resistance meter with indium-gallium electrodes applied to both ends of the sample.

Example 1 Powders of 517 parts by weight of lanthanum oxide, 167 parts by weight of chromium oxide, and 21.5 parts by weight of calcium carbonate were placed in a ball mill, wet mixed, dried, and then heated in an air atmosphere for 10 minutes.
Calcined lanthanum chromate (La,
90ao, i0rb3) powder was obtained.

Next, this calcined lanthanum chromate powder and commercially available zirconium oxide powder containing 5% by weight of yttrium oxide were mixed in a ball mill in various ratios, and an appropriate amount of PVA was mixed as a press binder into the resulting mixed powder, 1
After molding into a 57-X5X50ffF& square column under a pressure of ton/m2, samples 1 to 11 were obtained by firing at 1600°C for 2 hours in an air atmosphere. The strength and specific resistance of these samples were measured and the results are shown in Table 1.

From this table, it can be seen that when the amount of lanthanum chromate in which some of the lanthanum ions are replaced with calcium ions is less than 30% by weight based on the total amount of the sintered body, the conductivity is poor;
It can be seen that the mechanical strength decreases significantly when it exceeds

8- Example 2 Calcined lanthanum chromate (LaO,ll) obtained in Example 1
Add 50 parts by weight of zirconium oxide powders with different yttrium oxide contents to 50 parts by weight of CaO,lCr03) powder, dry the powder obtained by wet mixing in a ball mill, and mix an appropriate amount of PVA as a press binder to this,
After molding at a pressure of 1 tOn/C1n2, it was fired at 1600°C for 2 hours in an air atmosphere to obtain sample 12-19. The strength of these samples was measured and the results are shown in Table 2.

From this table, it is clear that the amount of yttrium oxide contained in the zirconium oxide must be between 6 and 10 weight ratios, and if it deviates from this range, the mechanical strength will be significantly reduced.

Table 2 Example 6 Predetermined amounts of each powder of lanthanum oxide, chromium oxide, and calcium carbonate were placed in a ball mill, wet-mixed, and then dried. This dry powder was calcined at 1000°C for 1 hour in an air atmosphere to obtain La1-XCaXCr03 ( Various calcined lanthanum chromate powders represented by x=0 to 0.6) were obtained.

Next, 50 parts by weight of a commercially available zirconium oxide powder containing 5% by weight of yttrium oxide was added to 50 parts by weight of these calcined lanthanum chromate powders.
After wet mixing in a ball mill and drying, the dry powder was mixed with an appropriate amount of PVA as a press binder, and 1t O
After molding at a pressure of rz 10112, 160 m
Samples 20 to 26 were obtained by firing at 0° C. for 2 hours. The specific resistance and strength of these samples were measured and the results are shown in Table 3.

It is clear from this table that mechanical strength decreases when the amount of calcium ions replacing lanthanum ions exceeds 0.4 mol per 1 mol of lanthanum ions before substitution.

Table 3 12-

Claims (1)

[Scope of Claims] 1 (A) zirconia containing 3 to 10% by weight of ittria and (B) lanthanum chromate represented by the compositional formula % (in the formula, X is 0 to 0.4), or It is a sintered body made of lanthanum chromate in which some of the lanthanum ions are replaced with calcium ions, and the ratio of component (A) to component (→ component is 6:7 to 7:6 based on weight). A conductive ceramic material characterized by: