JP2602036B2 - Manufacturing method of high strength zirconia ceramic - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a high-strength zirconia ceramic suitable for forming a mechanical component or the like.

[Conventional technology]

In order to obtain a high-strength zirconia-based sintered body, the mainstream method is to increase the strength by HIP so that the crystal phase is mainly composed of tetragonal crystals, the crystal grain size is kept to 1 μm or less, and pores that cause defects are eliminated. It is becoming.

[Problems of the prior art]

However, the current HIP apparatus is in an argon atmosphere, and a carbon container is mainly used as a container.
For this reason, although the sintered body after HIP can obtain high density, for example, if it is 3 mol Y ₂ O ₃ -ZrO ₂ , brownish black spots or unevenness occur in brownish color and the appearance is unfavorable. But only those with low commercial value were obtained.

In addition, 3 mol Y ₂ O ₃ -ZrO ₂ 80 (wt%) and Al ₂ O ₃ 20 (wt
%), The color becomes gray after HIP,
Black spots or unevenness were produced, and the appearance was similarly unsatisfactory.

[Means for solving the problem]

Therefore, the present invention has been made in view of the above problems, and has a transverse rupture strength of 70 kg / m.
After m ² or more of zirconia ceramics and HIP treatment, by oxidation treatment in an air atmosphere or oxygen (O ₂₎ of 20% or more of the atmosphere, high density, while maintaining a high strength, a color tone white or ivory It is characterized by obtaining a high-strength zirconia ceramic having no color unevenness or spots.

〔Example〕

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

Example 1 3 mol Y ₂ O ₃ —ZrO ₂ (specific surface area 12 m ² ) obtained by a coprecipitation method
/ g) A raw material was prepared by adding 2% of an acrylic binder to 100% by weight. Using this raw material, mold pressure
A product molded at 1000 kg / cm ² is cooled at a rate of 100 ° C / H 1430
C., kept for 2 hours, and fired at a heating rate of 100.degree. C./H.

Then hold at 1450 ° C for 2 hours with HIP device.
The treatment was performed under the condition of cm ² . Further, after re-sintering while changing the O ₂ atmosphere conditions and the sintering temperature, crystals, bending strength and color tone were confirmed.

In the atmosphere, it was not reoxidized at 1000 ° C or lower, and black or brown spots and color unevenness occurred in brown. In contrast, 1000
Above 50 ° C. and O ₂ 50%, the bending strength was maintained and the color was ivory, non-uniform and free of spots.

 Similar effects were obtained above 1200 ° C in the atmosphere.

However, at 1400 ° C or higher, since crystal growth occurs,
With this raw material, a result of around 1200 ° C. in the atmosphere was appropriate.

(Example 2) Raw material composition ZrO ₂ (average particle size 0.1 μm or less) 92% Y ₂ O ₃ (average particle size 0.5 μm or less) 4% CeO ₂ (average particle size 0.5 μm or less) 4% ZrO ₂ ball ( 100% water 100% water 100% Water The above materials are mixed with a rubber-lined rotary mill, and after 120 hours of operation, 3% of an acrylic binder is mixed and dried with a spray drier to obtain a raw material powder. Was manufactured. After the above-mentioned raw material was molded in a mold at a pressure of 1000 kg / mm ² , it was fired at a temperature rising / falling speed of 200 ° C./H at 1450 ° C. for 2 hours. further
The treatment was carried out at 1500 ° C. for 2 hours with a HIP device and at a pressure of 2000 kg / mm ² . This was changed in the O ₂ atmosphere condition and the firing temperature, and after firing again, the bending strength, crystal, and color tone were confirmed.

In the atmosphere, it was not reoxidized at 1200 ° C or lower, and black spots or color unevenness were observed in reddish brown. Under an atmosphere of 80% oxygen, the bending strength was maintained, the color was ivory, and no uneven spots were obtained.

At 1300 ° C. in the air, good crystals, flexural strength and color tone were obtained.

With this raw material, re-firing at around 1300 ° C in air was appropriate.

Example 3 Al ₂ O ₃ fine powder (average 0.5 μm) was added to 20% by weight of 3 mol Y ₂ O ₃ —ZrO ₂ fine powder (specific surface area 20 m ² / g) manufactured by coprecipitation method.
%, And a raw material powder containing 2% of an acrylic binder was prepared. The above-mentioned raw material was molded in a mold at a pressure of 1500 kg / cm ² , and then calcined at a temperature rising / falling rate of 200 ° C./H and 1400 ° C. for 2 hours. Furthermore, hold at 1430 ° C for 2 hours with a HIP device, pressure 200
The treatment was performed at 0 kg / cm ² . After changing the conditions of the oxygen atmosphere and the sintering temperature and sintering again, the crystal, bending strength and color tone were confirmed.

From these results, those in the air range from 1000 ° C. to 1300 ° C. were good.

〔The invention's effect〕

As described above, according to the present invention, the HIP effect is maintained by sintering the sintered body formed from the zirconia-based raw material and sintered again in an acidic atmosphere, and the color tone of the sintered body is also speckled. It becomes clear without any mechanical components, and furthermore, it is constituted by them, and the reliability of the device and the like can be improved.

Claims (1)

(57) [Claims] 1. A zirconia ceramic raw material is formed into a desired shape, and a sintered body having a transverse rupture strength of 70 kg / mm ² or more obtained by firing is densified by HIP treatment. A method for producing a high-strength zirconia ceramic, comprising oxidizing in an air atmosphere or an atmosphere having an oxygen content of 20% or more.