JPS5855376A - Manufacture of aluminum nitride 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 The present invention relates to a method for producing a sintered body of aluminum nitride,
1LKWIp actually maintains and exhibits all of the excellent properties inherently possessed by aluminum nitride itself, such as high thermal conductivity, and is highly dense.
The present invention relates to a method for manufacturing a sintered body.

Aluminum nitride (AJN) sintered body has attracted attention as a high-temperature material with essential characteristics such as heat resistance, corrosion resistance, and thermal shock resistance, and as a material with high thermal conductivity. ing.

By the way, in order for K to exhibit these various properties in the AjN sintered body, it is necessary that the jLIN sintered body be dense.For this reason, it has been difficult to establish a technology for manufacturing dense fk jkjN sintered bodies. Energy is being poured into.

Such a sintered body wire is usually obtained by pressure molding and pressureless sintering of A/N powder, but it is not possible to use A/N powder alone.
In addition, due to poor sinterability, a dense sintered body could not be obtained, and the sintered density was extremely low, at most around 80 times the true density of uN.

For this reason, attempts have been made to utilize a pressure sintering method using a hot press, but good results have not been obtained. A method of sintering by adding rare earth element oxides such as latom as a sintering aid has also been attempted.
A sintered body of fairly good quality was obtained.

However, rare earth element oxides are expensive and have a drawback in terms of 1 cosF, and A/N-YtOs-based sintered bodies have lower thermal conductivity than klN-only sintered bodies. The problem was that it was difficult to maintain and demonstrate the high thermal conductivity inherent to A/N.

Special Publication No. 11@50-23411 or Ceramics Association Journal No. SS*, pp. 330-336 (1981) Kt
A method for producing an AjN sintered body is disclosed in which calcium, barium, or strontium oxide or carbonate powder is added to MujN11 powder and sintered. The A/N sintered body using such additives becomes highly dense with a sintered density of 95 to 98% or more than 99% of the true density of the illusion R. In order to achieve high densification, KFi requires a sintering temperature of 1800° C. or higher in a normal non-oxidizing atmosphere. Therefore, there are economical disadvantages such as high consumption of the sintering furnace and high product cost.

An object of the present invention is to eliminate the above-mentioned disadvantages of the conventional method for producing an aluminum nitride sintered body, and to
It maintains and exhibits all of the excellent properties inherent to aluminum itself, such as high thermal conductivity, and it also has a relatively (low sintering rate) It is an object of the present invention to provide a method for manufacturing at a freezing temperature.

That is, the manufacturing method of aluminum nitride sintered body of the present invention,
Aluminum nitride powder, at least one titanate powder selected from calcium, barium, and strontium, or an oxide of calcium, barium, or strontium that becomes a titanate during sintering;
The method is characterized in that a powder made of a titanium oxide is added and mixed in an amount of titanate of 0.1 to 15% by weight, and then the mixed powder is molded and then sintered.

The most characteristic part of the present invention is aluminum nitride (A
/N) When molding and sintering the powder, the AjN
The purpose is to add at least one titanate selected from calcium, barium and strontium to the powder.

The titanate salt used in the present invention is usually calcium metatitanate (CaTi0. CaO1laO or 8rO and T1 other than the above-mentioned metatitanates such as barium orthotitanate (B'*TlO4), barium orthotitanate (arm Ti0i), etc.
0.02 or fractionated composite oxides may be used. Alternatively, calcium, barium or strontium oxides, carbonates, nitrates, sulfates, etc., which produce these titanates upon calcination, may be used. , TlO, or 2-part mixed powder may be used.-6 These titanates or mixed powders can be used alone or as a mixed system of two or more, and can be added to the AjN powder. For example, if the total composition weight of the mixed powder is 100%, CaTl0. , BaT10g or d8rT
In terms of iO,K, it works effectively even at a weight density of about 0.1, and it is possible to achieve high densification without compromising one of the excellent properties of the C, AjN sintered body, such as good thermal conductivity. If the amount added is too large, the excellent properties of the MN sintered body will be lost.If the addition amount exceeds 15% by weight, calculated as CaTiOs BaT10B or 8rTiOm, the growth of crystal grains will be inhibited. The strength of the sintered body gradually decreases, and the thermal conductivity also decreases.Therefore, the amount of at least one titanate selected from calcium, barium, and strontium added is 0.1
It is preferable to add 0.2 to 10% by weight of the total weight other than 15% by weight.

The mixed powder further contains paraffin, stearin,
A binder such as PVA may be added as a molding aid.

In order to improve sinterability, the aluminum nitride powder used in the present invention preferably has a particle size of 5 μm or less, and further preferably has a ti of 2 μm or less.

The thus obtained mixed powder is molded by compression at room temperature or the like, and then the molded body obtained is sintered. To prevent sintering, nitrogen gas (Nl), Aldun gas (human r),
Leaf gas (ru), or a mixture of these gases, or N
It is preferable to carry out the sintering in a non-oxidizing gas atmosphere such as a mixed gas of ten-carbon oxide (CO), or in a vacuum, and the sintering temperature is 1.
The temperature is preferably 500 to 1900°C, more preferably 1s50 to 1800°C.

If the temperature is less than 1,500°C, a highly dense sintered body cannot be obtained, whereas if it exceeds 1,900°C, MN separation begins. Further, in the case of using the mixed powder or the binder that produces a titanate upon firing as an additive, it is preferable to provide a step of calcining the molded body.

In addition, in the above explanation, the mixed powder is molded by cold compression and then sintered under normal pressure. However, in the method of the present invention, the mixed powder is molded using a Hora F press or the like. Alternatively, the obtained sintered body may be subjected to hot isostatic pressing (HIP') treatment, etc.
According to the method for producing an aluminum nitride sintered body of the present invention, at least one titanate selected from calcium, barium, and strontium is added to the aluminum nitride powder. By molding and sintering the mixed powder obtained by adding AjN, a highly dense sintered body having a sintered density close to the true density of AjN can be obtained. In addition, the conventional method of adding alkaline earth element oxides to uN powder requires a sintering temperature of 16°C in order to obtain such a highly dense sintered body.
According to the method of the present invention, a sintered density exceeding 99% of the true density of AJN can be obtained even at a sintering temperature of 1500°C or higher, compared to the case where the temperature had to be set at 00°C or higher. . Furthermore, a sintered body can be obtained that satisfactorily maintains and exhibits the excellent protection properties such as high thermal conductivity, heat resistance, corrosion resistance, and thermal shock resistance that AjN itself inherently has.

1111 ------- Example 1 95 parts by weight of MuIN powder with an average particle size of 0.9 μm and 0.95 parts by weight of CaTi powder with an average particle size of 1.6 μm. 5 parts by weight of powder were blended and mixed, and 5 parts by weight of I# rough-in was further added and mixed as a pastry finisher. The obtained mixed powder was molded at a molding pressure of 1 ton/- to obtain a plate-shaped molded product of 40 so* Place the sample in AjN Ruth I, fill it with the sample's circumference N K AjN powder as a nail powder, and then fill it with SN.
Sintering was performed at 1700° C. for 60 minutes in a rich atmosphere. As a result, a highly dense and highly thermally conductive sintered body having a relative density of 97 times higher than the true density of AJN was obtained.

Comparative Example 1 A mixed powder having the same particle size and the same composition as in Example 1 was used, except that CaTiOs powder was not mixed, and e* aggregates were obtained by the same method. The obtained sintered body was a porous body with a relative density of 75.

Examples 2 to 9, Reference Example 1 As Examples 2 to 9 and Reference Example 1, each mixed powder having the composition shown in Table 1 was obtained, and this mixed powder was molded under the same conditions as in Example 1. A swelling and soft molded body was obtained. Next, this molded body was cut and preheated at 400℃ in an atmosphere, and then Aj
The material was placed in a nitrogen chamber, filled with N K AjN powder as a filler powder, and sintered at 1700° C. for 30 hours in a normal atmosphere. The relative density and bending strength of the obtained sintered body were measured, and the zero crystallization was shown in Table s1.

Table 1 As is clear from Table 1, the aluminum nitride sintered body obtained by the method of the present invention is highly dense and has high mechanical strength.

Examples 10 to 15, Comparative Example 2 As Examples 1O to 15 and Comparative Example 2, mixed powders having the compositions shown in Table 2 were obtained, and the mixed powders were molded under the same conditions as Example 1 [same shape]. After preheating this molded body to 400°C in a N atmosphere,
It was placed in a JNN chamber, filled with surrounding K AjN powder as a filler powder, and sintered at the sintering temperature shown in Table 2 in a N atmosphere.
Sintered for hours.

The relative density and bending strength of the obtained sintered body were measured◇
The results are shown in Table 2.

Table 2 As is clear from Table 2, according to the method of the present invention, 15
Even at extremely low sintering temperatures of 50°C, the relative density is 9.
An aluminum nitride sintered body having a high density of 0% or more and high mechanical strength is obtained.

Example 16 95 parts by weight of AjN powder with average particle diameters t and sxm, 2 parts by weight of BILCO powder with an average particle diameter of 0.3 μm, and 3 parts by weight of Tie powder with an average particle diameter of 0.8 μm were mixed together. Then, 5 parts by weight of pine paste and C paraffin were added and mixed. The mixed powder thus obtained was molded and sintered under the same conditions as in Example 1. Relative density of the obtained sintered body was 96.SJG.

Example 17 95 parts by weight of MujN powder with an average particle size of 1.5 μm and 5 parts by weight of 8rTiO powder with an average particle size of 1.2 μm were blended and mixed, and further 5 parts by weight of Nono Rough In was added as a binder. was added and mixed. The thus obtained mixed powder was molded and sintered under the same conditions as in Example 1.

The relative density of the obtained sintered body was 97.5-.

Example 18 1 weight part of AjN powder with an average particle size of 1.2 μm (lF) and 1 part by weight of BaTiOs powder with an average particle size of 1.4 μm were mixed, and further 5 parts by weight of paraffin was added as a binder and mixed. did. The thus obtained mixed powder was molded under the same conditions as in Example 1.
A disc-shaped molded product with a size of
When sintered under the same conditions as above, a highly dense sintered body with good thermal conductivity was obtained.

Claims (1)

[Claims] Aluminum nitride powder, at least one titanate powder selected from calcium, barium and strontium, or an oxide of calcium, barium or strontium which can be converted into titanium salt by calcination, and titanium. An aluminum nitride sintered body characterized in that a powder consisting of an oxide is added in an amount of 0.1 to 15% by weight as a titanate, and then this mixed powder is molded and then sintered. II manufacturing method.