JPS63215563A - Zro2 base sintered body - 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 [Field of Industrial Application] The present invention relates to a ZrO3-based sintered body that is highly tough at high temperatures and has excellent thermal shock resistance.

[Conventional technology]

Conventionally, ZrO3-based sintered bodies made by adding stabilizers such as Y2O3 to ZrO3 and mainly consisting of quasi-stable tetragonal bodies undergo stress-induced transformation from square to monoclinic, resulting in poor toughness at low temperatures. Due to its high properties, it has been mainly used for cold-working tools such as knives and dies. However, the stress-induced transformation does not work at temperatures above 3 AO° C., resulting in a significant decrease in toughness.

Furthermore, ZrO3 alone is weaker in thermal shock than other SiN or SiC ceramics, and there has been a demand for improvement in thermal shock resistance. Therefore, in JP-A-61-101463 and JP-A-62-12662, there are examples in which A1□03 and mullite are added to ZrO3 in an attempt to improve thermal shock resistance. for the significant decrease in toughness.

There has been a demand for ZrOz-based ceramics that have not had much of an improvement effect and have both high-temperature toughness and thermal shock resistance.

[Problem that the invention seeks to solve]

As mentioned above, when ZrO□-based ceramics are used for high-temperature applications, their applications have been limited due to problems of decreased toughness and thermal shock resistance at high temperatures.

In view of the above facts, an object of the present invention is to provide a ZrO□-based sintered body having excellent high-temperature toughness and further excellent thermal shock resistance.

[Means for solving problems]

The present inventor conducted various studies in order to improve the toughness of ZrO-based sintered bodies at high temperatures, and as a result, A1□03
It has been found that toughness at high temperatures can be improved by adding and dispersing whiskers. moreover,
Adding and dispersing Al and O3 whiskers to a ZrO2-based sintered body containing Murai J is effective in improving thermal shock resistance, and in terms of strength, including A1□03 particles is effective. I have come to the conclusion that this is the case.

That is, the present invention provides a ZrO2-based sintered body characterized by containing 5 to 4097% of A1□03 whiskers and the remainder mainly consisting of ZrO2 having a tetragonal crystal structure, A1□O3 whiskers and mullite. , containing 5 to 70 wt% in total (
ZrO3-based sintered body, Al2O3, characterized in that the ZrO3-based sintered body contains 5 to 40 wt% of Al and O3 whiskers), and the remainder mainly consists of ZrOz having a tetragonal crystal structure.
Whiskers and A1□O1 particles total 5-70wt
% content (Al, 01 whisker 5-40wt%)
However, the remainder is ZrO, which has a mainly tetragonal crystal structure.
ZrO2-based sintered body characterized by consisting of 3, Al2
O3 whisker, At20. Contains a total of 5 to 70 wt% of particles and mullite (however, A1. O3 whisker 5
~40wt%), with the remainder mainly consisting of 2rO□ having a tetragonal crystal structure.

In the sintered body of the present invention, Y2O3, CeO3, MgO, etc., which are generally used as stabilizers, are appropriately added to ZrO3 alone or in combination to create a ZrOz-based sintered body having a mainly square crystal structure. Get a body.

A ZrO3-based sintered body having a square crystal structure is strong in cold conditions and is preferable in terms of processing, handling, etc.

The amount of stabilizer added is Y, 031-4wzo1%
, CeOz 4-16mo1%, ,MgO3-12m
It is appropriately selected within the range of o1%.

Next, the reason for limiting the components of the sintered body of the present invention will be described.

Addition of A1□03 whiskers is effective in improving toughness and acts up to high temperatures, so compared to the case of ZrO3 alone, it is possible to prevent a sharp decrease in toughness at high temperatures. If the amount added is less than 5wt%, the effect will be small.
+ If it is added in excess of 40 wt%, moldability will deteriorate and the cost will increase significantly.
It was limited to ~40 wt%.

Further, the addition of mullite lowers the thermal expansion coefficient of ZrO3 and improves the thermal shock resistance, and when it is contained in combination with Al and O3 whiskers or further with Al and O3 particles, the object of the present invention can be achieved. It is something. However, if added in a large amount, the strength will be greatly reduced, which will hinder practical application, so A1. O.

The total amount including whiskers etc. was limited to 5 to 70 wt%.

Next, A1□03 particles are effective in improving strength, especially at high temperatures, the decrease in strength is smaller compared to the case of ZrO3 alone, and in the present invention Al2O.

The object of the present invention can be achieved by containing whiskers or in combination with mullite.

However, when the amount of Al and O3 particles increases, the amount of A in the sintered body increases.
1□○, the number of like-minded interfaces increases, and on the contrary, the strength decreases rapidly, so a total of 5 to 70% i with At, O3 whiskers, etc.
It was limited to t%.

Furthermore, in order to obtain a sintered body with uniform composition and fine crystal grains, the method for manufacturing the sintered body of the present invention involves using powder having a particle size of 1 μm or less by a wet process such as a co-precipitation method. In order to reduce internal defects, after pre-sintering the density to 93% or more, hot isostatic pressing (HIP) is necessary.
) is preferably applied. HIP conditions are Ar gas, pressure 500 atm or more, temperature 1300-160
It may be within the range of 0°C. This is because if the temperature is lower than 1300°C, the crystal grains will not be densified, and if the temperature exceeds 1600°C, the crystal grains will become coarse.

〔Example〕

The present invention will be explained below based on examples.

Example l Zr0. The powder contains ZrO3, stabilizer Y2O1,
A commercially available powder (particle size: approximately 0.05 μm) prepared by a coprecipitation method and containing CeO2 and MgO as shown in Table 1 was used.

A1. The O3 powder has a particle size of about 0-03 μm, the ALO3 whisker has a diameter of about 1 μm and a length of 30-100 μm, and the mullite powder has a width of 0.1 μm, a length of 0.5 μm, and a thickness of 0.0 μm.
A commercially available product having a flaky shape of 0.01 μm was used.

However, in No. 4, Al and O3 are also ZrO3, y, o,
6 or more powders using powders manufactured by the coprecipitation method were blended so as to have the composition shown in Table 1, mixed wet in a ball mill, granulated in a spray dryer, and then 3 tons/kg in a rubber press. It was molded under the pressure of Al. After the molded body was temporarily sintered in the atmosphere at 1500° C. for lhr, it was further subjected to HIP treatment in Ar gas at 1450° C., 1o00at+*, and lhr maintained.

Using the sintered body obtained as described above, density, bending strength, fracture toughness, and thermal shock resistance were measured.

The bending strength was measured according to JIS standard R1601. Fracture toughness was measured at 20° C. and 700° C. by an indentation method using the Vickers indentation method, and calculated using Shinryo's formula. Thermal shock resistance was determined by holding the bending test piece at a constant temperature for 30 minutes, then putting it into water at 10°C, and expressing the temperature difference from the temperature at which the bending strength began to decrease.

Further, when the crystal structure of the sintered body of this example was examined by X-ray diffraction, 80% or more was tetragonal and the remainder was cubic.

In Table 1, No. 3 of the comparative example and No. 3 according to the example of the present invention.
005, A1. ○: Addition of whiskers has a large effect of increasing toughness. Comparing No. 5 and No. 8, it can be seen that addition of mullite is effective in improving thermal shock resistance.

In this example, the fracture toughness at 700°C was 3.
Moreover, the thermal shock resistance was 400°C or more.

〔Effect of the invention〕

As explained above, according to the present invention, a ZrO2-based ceramic having high fracture toughness even at high temperatures and excellent thermal shock resistance can be obtained, and is useful for wear-resistant parts, engine parts, etc.

Claims (1)

[Claims] 1 ZrO_ containing 5 to 40 wt% of Al_2O_3 whiskers, with the remainder having a mainly tetragonal crystal structure.
A ZrO_2-based sintered body comprising: 2 ZrO containing a total of 5 to 70 wt% of Al_2O_3 whiskers and mullite (however, 5 to 40 wt% of Al_3O_3 whiskers), and the remainder mainly consisting of ZrO_2 having a tetragonal crystal structure
_2 series sintered body. 3 Contains a total of 5 to 70 wt% of Al_2O_3 whiskers and Al_2O_3 particles (however, Al_2O_3
A ZrO_2-based sintered body characterized by having whiskers (5 to 40 wt%) and the remainder mainly consisting of ZrO_2 having a tetragonal crystal structure. 4 Contains a total of 5 to 70 wt% of Al_2O_3 whiskers, Al_2O_3 particles and mullite (however, Al
A ZrO_2-based sintered body comprising ZrO_2 having 5 to 40 wt% of _2O_3 whiskers and the remainder mainly having a tetragonal crystal structure. 5. The ZrO_2-based sintered body according to any one of claims 1 to 4, which uses powder having a particle size of 1 μm or less produced by a wet process such as a coprecipitation method. 6. The ZrO_2-based sintered body according to any one of claims 1 to 5, which is subjected to hot isostatic pressing (HIP) after pre-sintering.