JPH02129075A - Production of transparent compound sintered material of aluminum oxynitride - Google Patents

Abstract

PURPOSE:To obtain the subject sintered material having excellent transparency in a short time at a low temperature compared with conventional process by mixing a specific amount of a Y compound to a mixture of Al2O3 powder and AIN powder at a specific ratio and pressing and sintering the mixture under specific condition. CONSTITUTION:A mixture composed of 86.5-93.4wt.% of Al2O3 powder, 6.6-13.5wt.% of AIN powder and <=10wt.% of a Y compound (based on the above powders in terms or Y2O3) is sintered at 1750-1900 deg.C for 1-10hr under a pressure of >=100kgf/cm<2> to obtain a compound sintered material at least containing Al23O27N5 phase and Al11O15N phase as constituent matrices. The sintering can be promoted and performed at a lower temperature because the Y compound and the Al11O15N phase form liquid phase at a low temperature compared with Al23O275N. Al11O15N phase is formed in the sintered material when the ratio of Al2O3 to AIN is within the above range. When the sintering temperature is lower than the lower limit, the transparency of the product is deteriorated and when it exceeds the upper limit, sufficiently sintered material cannot be obtained. The transparency becomes poor when the sintering time is shorter than the lower limit and there is no formation of Al11O15N phase when the time is longer than the upper limit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a transparent quasi-aluminum nitride composite sintered body.

[Conventional technology]

Aluminum oxynitride is not an idiot with excellent high-temperature strength and thermal shock resistance, and because it belongs to the cubic crystal system, it has no optical anisotropy, and even in sintered polycrystalline materials, transparent bodies without light scattering can be obtained. . Therefore.

In recent years, expectations have increased for use as a heat-resistant window material in the visible and infrared regions.

Conventionally, transparent aluminum oxynitride sintered bodies have been produced by mixing aluminum oxide powder and aluminum nitride powder, as shown in Japanese Patent Application Laid-Open No. 0-1810/1.
It has been manufactured from Toto K by firing to form a single-phase aluminum oxynitride (calcining step), pulverizing this synthetic material into powder, shaping it, and sintering it again.

2. For example, as shown in Japanese Unexamined Patent Publication No. 58-14511, sufficient growth of crystal grains is required to impart translucency to aluminum oxynitride sintered bodies, and single-phase acid The sintering temperature for grain growth of aluminum nitride powder is ts
The temperature is as high as oo~2000°C, and the sintering time is over 20 hours.

[Problem to be solved by the invention]

Conventional methods for producing sintered bodies involve a calcination process, which increases the chance of contamination of the i-material powder with impurities.

This becomes a factor that impairs the translucency of the sintered body. In addition, there was a problem in that, as mentioned above, high temperatures and long periods of time were required to impart translucency.

The present invention was made to solve such problems,
The purpose of the present invention is to obtain a method for producing a transparent aluminum oxynitride composite sintered body with excellent translucency at a lower temperature and in a shorter time than conventional methods.

Means for Solving CHM] The method for producing a transparent aluminum oxynitride composite sintered body of the present invention uses aluminum oxide powder @15, ~93.4% by weight.
and aluminum nitride powder & 6 to 13.51% by weight and 10% by weight or less of yttrium compound in terms of ytria to both of the above powders, and 1 to 10% by weight at 1750 to 1900°C under a pressure of 100yf/i or more. Time sintered and at least AJ! 25027N5 phase and Al1
1015N phase as a constituent matrix.

In addition, there is a method for producing a transparent aluminum oxynitride composite sintered body according to another invention of the present invention, in which aluminum hydroxide powder gQ, T
~! 5.11% by weight, aluminum nitride powder 4.4~L
The yttrium compound is converted into yttrium and is 10 il for the 3-layer ratio and both of the above powders! Mixed at t% or less,
100 to 1750 to 11 under pressure of 9f/cd1 or more
Sinter at 100°C for 1 to 1 hour.

At least A723027N phase and AJ11015N
The phase is formed as a constituent matrix.

[Effect]

Yttrium compound and AJ 1101s in the present invention
Since the N phase forms a liquid phase at a lower temperature than the Al2!5O27NS phase, the presence of the liquid phase promotes sintering, lowers the temperature, and increases the theoretical density of sI required to impart transparency. % or more becomes a dense body.

〔Example〕

In the present invention, aluminum oxide powder 86.5 to I
t% by weight, preferably 2.5% by weight of StS-I and aluminum nitride powder at 6-115% by weight, preferably 1.5-11. Mix % by weight of S.

By mixing within the above range, Al11015N is added to the sintered body.
A phase is generated, and the desired purpose can be achieved by the above action. The above mixing ratio is based on Anozi, which is a compound normally made in the production of single-phase aluminum oxynitride.
The aluminum oxide powder is mixed in excess compared to the molar ratio s:S of Al2O5 and AlN in ozyNs aluminum oxynitride. Further, the average particle size of the aluminum oxide powder and the aluminum nitride powder is preferably 3 μm or less, more preferably 2I! m or less.

If the particle size of the powder is large, even if sufficient mixing is performed, the reaction will proceed completely and there is a risk that unreacted portions will remain in the sintered body.

Furthermore, 100 weight or less of yttrium compounds such as yttrium, yttrium fluoride, and yttrium chloride are added to both of the powders and mixed. It is important not to add yttrium compounds, which form a liquid phase at relatively low temperatures and contribute to promoting sintering, but they scatter during sintering.

It is not necessary to add it in excess, and it may desirably be added in an amount of 3% by weight or less.

After the above mixed powder is granulated and sized, it is molded by a mold pressing method or the like. The molded body is set in a hot press carbon die and heated at 1750-100°C f1 in nitrogen, for example.
Hot press sintering is carried out for ~10 hours, preferably 1-6 hours. The hot pressing is carried out at a pressure of 100 to 9/d or more, preferably 200 Yu/crI1 or more, which is necessary to remove and reduce the pores and promote the densification of the sintered body.

Note that below 1750°C, the transparency of the sintered body decreases, and 1
! At temperatures above 900°C, the sample powder melts and a sufficient sintered body cannot be obtained. Furthermore, if sintered for less than 1 hour, a sufficient sintered body to become transparent cannot be obtained, and if sintered for more than 10 hours, A711
015N There is no phase and the intended purpose cannot be achieved.

In another invention of the present invention, aluminum hydroxide powder 9
3.7~! 46% by weight, preferably 3λ3~s5% by weight
and aluminum nitride powder 44-9.3 F#%,
Preferably, 923 to 923 to SS weight % is mixed. By mixing within the above range, a KAl11015N phase is generated in the sintered body,
The desired purpose can be achieved by the above action.

Aluminum hydroxide easily becomes aluminum oxide by heating, but the above mixing ratio is 9:5 molar ratio of AJ205 of AI 25027 N5 aluminum oxynitride, which is usually synthesized as single-phase aluminum oxynitride, and MujN.
This results in an excessive amount of aluminum hydroxide powder being mixed in compared to other methods. In addition, aluminum hydroxide powder and aluminum nitride S
+ The average particle size of the rum powder is preferably 3 μm or less, 1.5 μm.
It is even more desirable if it is less than m. Aluminum hydroxide becomes activated aluminum oxide through dehydration by heating, and the reaction to aluminum oxynitride progresses relatively quickly, but if the diameter of the powder is large, there is a risk that unreacted parts may remain in the sintered body. There is.

Furthermore, the effect of the yttrium compound added and mixed with 10% by weight or less in ytria conversion 1 to the above-mentioned powders and the effect of the amount added are the same as described above.

After granulating and sizing these mixed powders, sintering is performed by a mold pressing method or the like under the same sintering conditions as in the present invention.

When the microstructure of the aluminum oxynitride composite sintered body obtained as described above and according to the embodiment of the present invention was observed using a scanning electron microscope, sufficient grain growth and densification with a crystal grain size of 10 to 100 μm occurred. ing.

Further, from xwla diffraction and electron diffraction using a transmission electron microscope, it can be seen that at least two phases, J2302705 aluminum oxynitride and A411015N aluminum oxynitride, are the constituent components.

A411015N phase is jlJ2B027N5
Similarly to the addition of yttrium compounds, which form a liquid phase at a lower temperature than the phase, they contribute to promoting sintering and lowering the temperature.

The present invention will be specifically explained below using examples.

Example 1 Aluminum oxide powder with purity SS, S% or higher and purity 93
．． % or more of aluminum nitride powder by L1% by weight, and 3% by weight of ittria with a purity of SS% or more as a sintering agent for both of the above powders were placed in a polyethylene pot, and alumina balls with a purity of StS% or more were placed in ethanol. Perform ball mill mixing using The average particle diameters of the above aluminum oxide powder and aluminum nitride powder are 2.3 μm and 0.7 μm, respectively, when measured using a centrifugal sedimentation type particle size distribution analyzer manufactured by Takasu Seisakusho.

After mixing and drying the nine powders, they are granulated and molded using a mold press method. The molded body was set in a carbon die for hot press, and heated at 1800°C for 3 hours in nitrogen at zsOkg/c.
A transparent aluminum oxynitride composite sintered body according to an embodiment of the present invention was manufactured by hot pressing at a pressure of d.

Example 2 The molded product in Example 1 was set in a carbon die for hot pressing and heated at 1750°C for 1 hour in nitrogen.

Two transparent aluminum oxynitride composite sintered bodies according to other embodiments of the present invention were manufactured by hot pressing at a pressure of 230 kff/cd.

Example 3 Aluminum hydroxide powder 93j weight t% with purity of 99% or more
and 12% by weight of aluminum nitride powder with a purity of s1% or more and itria with a purity of 99% or more as a sintering agent were placed in a polyethylene pot at 3% by weight for both of the above powders, and alumina balls with a purity of 5ils% or more were added in ethanol. Perform ball mill mixing using The average particle diameters of the above aluminum hydroxide powder and aluminum nitride powder are 1.0βm and 0.7μm, respectively, when measured using a centrifugal sedimentation type particle size distribution analyzer manufactured by Takasugi Seisakusho.

The mixed powder is dried, then granulated, and molded using a mold press method. The molded body was set in a carbon die for hot press, and heated at 11,100°C for 3 hours in nitrogen at z30kg/
c++! A transparent aluminum oxynitride composite sintered body according to an embodiment of another invention of the present invention was manufactured by hot pressing under pressure.

Example 4 The powder compact in Example 3 was set in a carbon die for hot press, and heated at 1150°C for 1 hour at 230°C in nitrogen.
2 by hot pressing with #/c-IA pressure.
A transparent aluminum oxynitride composite sintered body according to another embodiment of the present invention was obtained.

Comparative Example: The same γ-type acid aluminum oxide powder 8S, 3, 14% by weight as used in Example 1 was mixed in the same manner as in Example 1.

Shape. The molded body was set in a carbon die for hot pressing, and hot pressed at 130°C for 3 hours under a pressure of 400 f/cd. An aluminum oxynitride sintered body was manufactured.

Comparative Example 2 Aluminum oxide powder 8S. with a purity of 93.9% or more. 3% by weight and 14.7% by weight of the same aluminum nitride powder used in the example were mixed and molded in the same manner as in the example. The compact was set in a carbon die for hot pressing and hot pressed under the same conditions as in Example 3 to produce an aluminum oxynitride sintered body.

The diffraction peaks of the sintered bodies obtained in Examples 1 to 4 and Comparative Example 1.2 were determined by an X-ray diffraction experiment. As a result, peaks for both Al25027NS aluminum oxynitride and A/1i015N aluminum oxynitride can be seen in the example, but in the comparative example, peaks for both Al25027NS aluminum oxynitride and A/1i015N aluminum oxynitride are observed.
Only the peak of aluminum pentaoxynitride was observed.

In addition, the sintered bodies obtained in Examples 1, 2.3 and Comparative Example 1.2 were processed to a thickness of 21111 mm, polished on both sides, and then measured in the infrared region using an infrared spectrophotometer manufactured by JASCO Corporation. Transmittance was measured. The results are shown in the characteristic diagram showing the change in transmittance depending on the wavelength in the drawing. In the figure, the horizontal axis shows the wavelength (βm), the vertical axis shows the transmittance (%), (1) is the characteristic of Example 1, (2
) are characteristics of Example 2.

(3) is the characteristic of Example 3, (4) is the characteristic of Example 4, U
υ indicates the characteristics of Comparative Example 1, and 112 indicates the characteristics of Comparative Example 2.

As can be seen from the drawings, Examples 1 and 3 showed high transmittance, and Examples 2. Even though the sintering temperature was as low as trso°C, Example 4 exhibited a transmittance that slightly exceeded that of the comparative example.

The density of the sintered bodies of the above examples was measured by the Archimedes method, and it was found that all of them were dense bodies with a theoretical density of 9 g% or more.

〔Effect of the invention〕

As explained above, the present invention is based on aluminum oxide powder SS.
．． S~93.4% by weight, aluminum nitride powder 1L6~
1F 5% by weight and 10% by weight or less of yttrium compound in terms of yttrium for both powders, or aluminum hydroxide powder 9 (L7~95.6% by weight, aluminum nitride powder 44~!L3 heavy weight% and A yttrium compound of 10% by weight or less in terms of yttrium was mixed with both powders, and the mixture was heated under a pressure of 100 kgf/cd1 or more.
By sintering at 750°C to 100°C for 1 to 10 hours to form at least the 3027N5 phase and the AA110j5N phase as a constituent matrix, the temperature is lower than that of the conventional method.

A method for producing a transparent aluminum oxynitride composite sintered body with excellent translucency can be obtained in a short time.

[Brief explanation of the drawing]

The drawing is a characteristic diagram showing the change in transmittance depending on the wavelength of a sintered body comparing an example of the present invention and a conventional example. In the figure, (1) is the characteristic of Example 1, (2) is the characteristic of Example 2, (3) is the characteristic of Example 3, and (4) is the characteristic of Example 4.
Characteristics of. afl is the characteristic of Comparative Example 1, and α is the characteristic of Comparative Example 2.

Claims (2)

[Claims] (1) Aluminum oxide powder 86.5-93.4% by weight
, 6.6 to 13.5% by weight of aluminum nitride powder and 10% by weight or less of yttrium compound in terms of yttrium are mixed with both of the above powders, and 100 kgf/cm^
A method for producing a transparent aluminum oxynitride composite sintered body, which comprises sintering at 1750 to 1900°C for 1 to 10 hours under two or more pressures to form at least an Al_2_3O_2_7N_5 phase and an Al_1_1O_1_5N phase as a constituent matrix. (2) 90.7 to 95.6% by weight of aluminum hydroxide powder, 4.4 to 9.3% by weight of aluminum nitride powder, and 10% by weight or less of an yttrium compound in terms of yttria are mixed with both of the above powders; 100kgf/cm^
1. A method for producing a transparent aluminum oxynitride composite sintered body, which comprises sintering at 1750 to 1900° C. for 1 to 10 hours under two or more pressures to form at least an Al_2_3O_2_7N phase and an Al_1_1O_1_5N phase as a constituent matrix.