JP2946342B2 - High strength color zirconia sintered body and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color zirconia ceramic, and more particularly to a yellow, low-temperature sinterable zirconia ceramic.

[Problems to be solved by conventional technology and invention]

Zirconia sintered bodies, especially tetragonal zirconia sintered bodies, are being applied to household goods such as cutting tools and sports goods such as golf shoes spikes due to their high strength and beautiful surface gloss after mirror polishing. Applications to decorative components such as cases and accessories are also expanding. In order to cope with such expanding use, color zirconia having various colors is demanded.

As a method for producing color zirconia, a method of adding a pigment (mainly an oxide) to stabilized zirconia, mixing and sintering (Japanese Patent Laid-Open No. 59-50050), a method of adding a small amount of a colorant (mainly A method of producing a solid solution of rare earths by a coprecipitation method or the like (JP-A-62-59571) is known as a method for producing powder.

However, in the method of mixing the above-mentioned color pigments, the addition amount is relatively large, so that the sintering is difficult, and the properties of the sintered body, particularly the mechanical strength is reduced. However, there still remains a problem that it is difficult to produce clear colors because of the difficulty in producing the color. Further, the method in which a small amount of a colorant is dissolved in a solid solution by the coprecipitation method has a disadvantage that the color density is low and the color is indistinct as color zirconia and the use thereof is limited. In addition, there is no particular improvement in the sinterability of these two methods, and the pigment addition method has a serious problem that the sinterability is rather lowered and the strength is lowered. Therefore, sintering was not easy in the content addition method, for example, high-temperature high-pressure sintering (HIP treatment) was commonly used.

An object of the present invention is to solve the drawbacks of the conventional colored zirconia, and in particular, to obtain yellow colored zirconia in a clear color without lowering the strength.

[Means for solving the problem]

The color zirconia sintered body according to the present invention is composed of ZrO ₂ containing a stabilizer and a small amount of a coloring agent and a sintering aid, and has a low sintering temperature, a clear color tone, and a high mechanical strength yellow. It is a zirconia sintered body.

A praseodymium (Pr) compound is used as a coloring agent, and a coprecipitation method, an oxalate method, and a stabilizer are used in zirconia.
When added and solid-dissolved by evaporation to dryness method, hydrolysis method, etc., water-soluble compounds, specifically chlorides, nitrates, etc. can be used,
In addition, when added to ZrO ₂ powder that already contains a stabilizer, oxides, acetates, carbonates, and the like can be used in addition to the water-soluble compounds described above, and the amount of oxides in the sintered body is stabilized. It is preferably added in an amount of 0.01 to 0.1 mol% with respect to ZrO ₂ containing the agent, in an amount of about 0.03 mol% to 0.07 mol%.

As a sintering aid, a Zn compound is used. However, it is necessary to limit the type of the compound as long as it becomes an oxide after firing, such as insoluble compounds such as oxides and carbonates, and soluble compounds such as acetates and chlorides. However, it is added so that the amount of the oxide in the fired body is 0.1 to 0.6 mol% based on ZrO ₂ containing a stabilizer.

As the stabilizer, when the obtained yellow zirconia sintered body requires high strength, a Y compound which becomes Y ₂ O ₃ after firing is most preferable (1.5 mol% to 7.0 mol% as an addition amount). Then, CeO ₂ (addition amount: 10% to 16% by mole) is preferable. However, when high strength is not required, Ca compound (which becomes CaO after firing: 8 to 12% by mole) or Mg compound (calcination After M
g: 16-26 mol%) can also be used as a stabilizer.

In the present invention, the content of the colorant, Zr containing a stabilizer
The reason for limiting the amount to 0.01 to 0.1 mol% with respect to O ₂ is that if the colorant is less than 0.01 mol%, it is difficult to obtain a coloring effect.
This is because the coloring effect no longer changes even if it exceeds mol%.

In the present invention, the addition amount of the sintering aid, including a stabilizer
The reason for limiting the amount to 0.1 to 0.6 mol% with respect to ZrO _{2 is} that if the sintering aid is less than 0.1 mol%, the effect of the auxiliary is difficult to be obtained.
If the amount exceeds mol%, the properties of the sintered body are adversely affected.

Although the calcining temperature in the present invention is 800 to 1100 ° C., the specific surface area of the calcined powder obtained is larger as the calcined temperature is lower, and the calcined temperature is lower as the calcined temperature is higher. What is necessary is just to select by specific surface contact. Therefore, the specific surface area 15
If it is desired to obtain a powder of up to 20 m ^2, a calcining temperature of about 900 ° C., and if it is desired to obtain a powder of 6 to 10 m ^2, a calcining temperature of about 1000 to 50 ° C. is preferable.

Sintering temperature of at yellow zirconia present invention varies depending on the specific surface area and a molding pressure of powder, usually specific surface area 6 m ²
1300-1400 ° C. molding pressure in the case of the hydrostatic pressure 2t / cm ² powder
Thus, a sintered body having a specific surface area of 15 m ^{2 and} a sintering temperature of 1200 to 1300 ° C. having a theoretical density of 98% or more can be obtained. This sintering temperature is usually set to a commercially available zirconia powder (specific surface area: 10 to 15).
m ²⁾ which is of 200 to 300 [° C. lower temperature than the sintering temperature (from 1,450 to 1,500 ° C.). Further, the bending strength of the obtained yellow zirconia sintered body is, when compared with the JIS standard three-point bending method, a commercially available zirconia sintered body (Y ₂ O ₃ content 3 mol% product)
Shows strength equal to or higher than.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 In manufacturing a high-strength yellow zirconia sintered body, 200 g (1.123 mol) of zirconium oxychloride ZrOCl ₂ and YCl ₃ 9.1 were used.
An acidic aqueous solution in which 64 g (0.0469 mol) and 0.870 g (0.0352 mol) of PrCl ₃ were dissolved was added dropwise to aqueous ammonia, and the coprecipitate produced was filtered, washed with water, washed with alcohol, and dried at 110 ° C. under reduced pressure. The obtained dried powder is calcined at 1000 ° C. for 3 hours,
A powder having a specific surface area of about 6 m ² was obtained. 100 g of this calcined powder (0.812
Mol), and 0.536 g (0.00244 mol) of zinc acetate dihydrate and 250 ml of ethanol were added. The mixture was ball-milled with zirconia balls for about 24 hours, and the slurry was evaporated to dryness to obtain a raw material powder.

A compact obtained by press-molding this powder under a hydrostatic pressure of 2 t / cm ² was fired at 1300 ° C. for 3 hours to obtain a yellow zirconia sintered body. Density and bending strength of the obtained sintered body (JIS standard three-point bending test), K _IC value (Vickers indentation method)
As shown in Table 1, a high value was obtained.

Example 2 200 g (1.123 mol) of zirconium oxychloride ZrOCl ₂ , Y
Cl ₃ 9.164g (0.0469 mol), PrCl ₃ 0.870g (0.0352 mol)
An aqueous solution in which oxalic acid was dissolved in an amount of at least twice the amount of these compounds was added dropwise to an acidic aqueous solution in which oxalate was dissolved. After baking, a powder having a specific surface area of 15 m ² was obtained.
To 100 g (0.812 mol) of this calcined powder, 0.306 g (0.0
[0244 mol] and 250 ml of ethanol were added, and the mixture was ball-milled using zirconia balls for about 24 hours, and then the slurry was evaporated to dryness to obtain a raw material powder.

This powder was formed by isostatic pressing in the same manner as in Example 1
It was fired at 00 ° C. for 3 hours to obtain a yellow zirconia sintered body. Table 1 shows the density and mechanical properties of the obtained sintered body.

Example 3 100 g (0.812 mol) of zirconia powder having a specific surface area of 15 m ² containing 2 mol% of Y ₂ O ₃ was well dispersed in 250 ml of an acidic aqueous solution containing 0.604 g (0.00244 mol) of PrCl ₃ using a ball mill or the like, and then a Pr compound was prepared. The mixed precipitate of Pr oxalate and zirconia powder obtained by dropping 250 ml of an aqueous solution containing oxalic acid in a molar amount of twice or more of the above was filtered, washed with water, washed with ethanol, dried under reduced pressure, and then dried under reduced pressure.
The powder was calcined at a temperature of 3 hours for 3 hours to obtain a powder having a specific surface area of 6 m ² . To 100 g of the calcined powder, 0.536 g (0.00244 mol) of zinc acetate dihydrate and 250 ml of ethanol were added, and the mixture was ball-milled with zirconia balls for 24 hours. The slurry was evaporated to dryness to obtain a raw material powder. The obtained powder was molded in the same manner as in Example 1, and 1300
C. for 3 hours to obtain a yellow zirconia sintered body. Table 1 shows the properties of the obtained sintered body.

Comparative Example 1 Praseosium oxide Pr ₆ O ₁₁ 0.415 g (0.406 mmol) was added as a coloring material to 100 g (0.8113 mol) of a commercially available zirconia powder (specific surface area 15 m ² ) containing 3 mol% of Y ₂ O _3. After ball milling for an hour, the slurry was evaporated to dryness to obtain a raw material powder. The obtained powder was molded in the same manner as in Example 1 and fired at 1200 ° C.

 Table 1 shows the results of the obtained sintered bodies.

Comparative Example 2 Zirconium oxychloride ZrOCl ₂ 200 g (1.123 mol), Y
An acidic aqueous solution in which 9.164 g (0.04693 mol) of Cl _{3 and} 0.870 g (0.00352 mol) of PrCl ₃ were added dropwise to aqueous ammonia was filtered, and the resulting coprecipitate was filtered, washed with water, and washed with alcohol.
It dried under reduced pressure at 0 degreeC. The obtained dried powder was calcined at 1000 ° C. for 3 hours to obtain a powder having a specific surface area of 6 m ² . The calcined powder was ball milled for 24 hours using ethanol and zirconia balls, and the obtained slurry was evaporated to dryness to obtain a raw material powder. The obtained powder was molded in the same manner as in Example 1,
For 3 hours.

 Table 1 shows the properties of the obtained sintered body.

In the above example, the case where Y ₂ O ₃ was used as the stabilizer was shown. However, when other stabilizers (CeO ₂ , CaO, MgO) were used, the same low-temperature sintering characteristics were exhibited. A sintered body having a high density and a high strength at a lower temperature than that of the comparative example can be obtained.

〔The invention's effect〕

A yellow zirconia sintered body having a low sintering temperature, a clear color tone, and high mechanical strength can be obtained.

Claims (3)

(57) [Claims] To 1. A ZrO ₂ containing stabilizing agent, a Pr ₆ O ₁₁ 0.01
A sintered body of yellow zirconia containing 0.1 to 0.6 mol% of ZnO and 0.1 to 0.6 mol% of ZnO. 2. A compound obtained by calcining a mixture obtained from a solution containing a stabilizer, a zirconium compound that becomes ZrO ₂ after firing, and a praseodymium compound that becomes Pr ₆ O ₁₁ after firing, and then generating zinc oxide by firing. Characterized by uniformly adding, mixing, and forming and firing. 3. A yellow zirconia powder characterized by being calcined after adding a Pr compound to zirconia powder containing a stabilizer, further adding and mixing a zinc compound which generates zinc oxide by firing, firing after molding. The method of manufacturing the aggregate.