JPS60210571A - Silicon carbide-containing alumina sintered body and manufacture - 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 an alumina sintered body containing ashed silicon and a method for producing the same, and more specifically, an alumina sintered body containing ashed silicon particles uniformly containing expanded silicon particles and having excellent mechanical properties, thermal conductivity, and electrical insulation properties. This article relates to an excellent alumina sintered body and its manufacturing method.

In general, alumina sintered bodies are materials with excellent hardness, room temperature strength, heat resistance, chemical stability, and electrical insulation, and are widely used in corrosion-resistant and wear-resistant parts, electronic industry parts, spark plug parts, etc. ing. Recently, energy conservation and new energy sources have become important issues, and many attempts have been made to use ceramics as high-temperature mechanical parts due to their properties such as heat resistance, corrosion resistance, and light weight. Among them, alumina sintered bodies are attracting attention as high-temperature mechanical parts, but their hardness, strength, cleaving properties, fracture resistance, and thermal shock resistance at high temperatures have not reached sufficient properties. Further, with the development of the electronic industry, electronic component materials such as semiconductors are becoming faster and more highly integrated. Therefore, the amount of heat generated within the integrated circuit increases, and the heat dissipation performance of the substrate material has become an important issue. By the way, alumina sintered bodies have been put to practical use as substrate materials for the electronic industry, but as mentioned above, they have low thermal conductivity and poor heat dissipation properties as substrate materials for integrated circuits that are becoming faster and more integrated. This is a big problem because it is inferior.

As materials for solving the above problem, hot-pressed alumina fibers produced by sintering high-purity alumina powder under high pressure at material temperature, or composite materials of whiskers and alumina are being considered. However, the hot-pressed sintered body does not have sufficient thermal conductivity, high-temperature strength, or fracture resistance, the cost of high-purity alumina powder as a raw material is high, and productivity is poor. Although the single crystal has improved thermal conductivity and high l crystal strength, it is extremely expensive. Furthermore, composite materials of ashed silicon fibers or whiskers and alumina have improved high-temperature strength and fracture resistance in specific directions of the material, but the fibers or whiskers and alumina must be uniformly dispersed in all directions. However, it is difficult to completely improve the properties in all directions, which is a drawback.

The present inventors have devoted themselves to research into an alumina pressureless sintered body that can solve the above-mentioned drawbacks, and have found that mechanical properties,
We have completed an alumina sintered body containing silicon carbide with excellent thermal conductivity and electrical insulation, and a method for manufacturing the same.

Next, the present invention will be explained in detail.

An object of the present invention is to provide an alumina sintered body uniformly containing silicon carbide particles and a method for manufacturing the same.

According to the present invention, when silicon ash particles are uniformly contained in an alumina pressureless sintered body, hardness, strength, fracture resistance, thermal conductivity, and thermal shock resistance are significantly improved. The reason for this is that silicon carbide is essentially an extremely hard material, so the hardness of an alumina sintered body containing silicon ash improves, and the silicon ash is uniformly dispersed as fine particles. The strength of the alumina pressureless sintered body is also improved. In addition, since silicon ash and alumina have different chemical compositions, crystal structures, and other properties, compositional and (V + j) non-uniformity occurs between microscopic silicon ash particles and alumina particles.
Based on this, when a fracture crack propagates, the propagation energy is consumed to prevent the crack from progressing, thereby improving fracture resistance. Furthermore, since silicon carbide is a material with excellent thermal conductivity, the thermal conductivity of an alumina sintered body containing silicon carbide uniformly throughout is improved.

According to the present invention, the silicon ash contained in the alumina pressureless sintered body must be in a range of 0.5 to 40% by weight. If the silicon carbide content is less than 0.5%, improvements in hardness, strength, fracture resistance, and thermal conductivity based on silicon carbide bonding will not be sufficient, and if it is more than 40%, the sinterability of alumina and silicon ash will be insufficient. However, even if a high-density sintered body could be obtained, there would be extremely large non-uniform areas between the silicon ash particles and the alumina particles. This is because silicon ash significantly reduces mechanical and thermal properties.
The most preferable result is obtained in the range of ~20%.

According to this experiment, SiO2, MgO1CaO1SrO, BaOlM
nO2, F e O2, Ti0z, Z r Oa, Pb
An alumina material containing ashed silicon, characterized in that the starting material is a mixture containing 0.1 to 20% of one or more additives of 0% Cr2es and B2O3, with the balance mainly consisting of alumina. A sintered body is preferable. The reason for this is that when the additives are included, a low melting point compound is formed between the alumina and the alumina, and a dense pressureless sintered body can be easily obtained at a relatively low temperature. Furthermore, if the sintering temperature is high, impurities will diffuse into silicon carbide, greatly reducing its thermal conductivity, whereas if the sintering temperature is low, the diffusion of impurities will be prevented, resulting in a sintered body with excellent thermal conductivity. is obtained. The additive is 0.1%
If the additive content is less than 20%, there will be less low-melting point compounds produced, so there will be little effect; if the additive content exceeds 20%, a lot of low-melting point compounds will be produced, and the high-temperature mechanical properties of the pressureless sintered body will deteriorate. It is preferably in the range of 0.1 to 20%.

According to the present invention, the average particle size of the silicon ash is 0.05 to 5.
0 μm, and the average particle size of alumina is 0.5 to 50 μm.
L is preferable. The reason for this is that if the average particle size of silicon ash is smaller than 0.05 μm, it will have an effective effect on the strength of the alumina pressureless sintered body. This is because it is necessary to be supported more than that. Generally, it is extremely difficult to uniformly disperse ultrafine ceramic particles in other ceramics.

Further, according to the present invention, it is difficult to uniformly contain a sufficient amount of silicon carbide with a diameter of 0.05 μm or less.

If the average particle size of silicon carbide is larger than 5.0 μm, the structural non-uniformity between the silicon carbide particles and the alumina particles becomes large, and the mechanical and thermal properties of the alumina pressureless sintered body deteriorate. This is because it is difficult to improve the average particle size of silicon carbide. Among these, it is most preferable that the average particle size of silicon carbide is in the range of 0.1 to 0.4 μm.
If it is smaller than m, it will be difficult to obtain a sufficiently high-density alumina cold sintered body, the mechanical properties and thermal properties of the alumina cold sintered body will be insufficient, and on the other hand, the average particle size of alumina will be 60 μm. The mechanical t of the alumina sintered body is larger than
This is because by6 is significantly reduced. Among these, it is preferable that the alumina is silicon nitride having an average particle size in the range of 1.0 to 10 μm. The reason for this is that β-type silicon carbide has a cubic crystal system and does not exhibit anisotropy in the physical properties of its particles, so that an alumina sintered body having a stable microstructure can be obtained. Further, the crystal structure of alumina is preferably α-type alumina. The reason for this is that α-type alumina has excellent stability at high temperatures.

According to the present invention, silicon carbide is preferably uniformly dispersed in the alumina sintered body. The reason for this is that if silicon carbide is not uniformly dispersed, the physical properties of the alumina sintered body will be non-uniform, and furthermore, if the uniformity is significantly compromised, unsintered parts will occur in the alumina sintered body, and the alumina sintered body will become unsintered. This is because the mechanical properties and thermal properties of the pressureless sintered body show significant deterioration.

According to the present invention, the bulk density of the alumina sintered body containing silicon carbide is preferably 90% or more of the theoretical density.

The reason for this is that if the theoretical density is less than 90%, there will be many pores inside the sintered body, and the thermal conductivity will decrease.

Next, a method for manufacturing an alumina sintered body containing silicon carbide according to the present invention will be described.

According to the present invention, an alumina sintered body containing silicon carbide is manufactured based on the manufacturing process shown in the drawings. That is, the weight ratio is 0.5 to 40% silicon carbide powder and the balance is alumina powder, and if necessary, 5if2, Mg0%C
aO1SrO, Bad, Mn0z, Fed, TiO2
, ZrolPbO%Cry, 8203 in an amount of 0.1 to 20%, water or an organic solvent is added to the mixture, and the mixture is sufficiently mixed in a hole mill or the like, and then molded. By inserting the molded body into a firing furnace in which the atmosphere is controlled and sintering it under pressure at a temperature of 1400 to 1900°C, an alumina pressureless sintered body containing silicon carbide is obtained.

According to the present invention, the average particle size of the silicon carbide powder is 0, O
1 to 4.0 μm, and the average particle size of the alumina powder is 0.0 μm.
It is necessary that the thickness is 05 to 40 μm. The reason is,
This is because if the average particle size of the silicon carbide powder is smaller than 0.01 μm, the agglomeration is extremely strong and the dispersibility during mixing is low. This is because the mechanical properties a and thermal properties of the alumina pressureless sintered body deteriorate as the alumina pressureless sintered body becomes larger. In addition, if the average particle size of the alumina powder is smaller than 0.06 μm, the bulk specific gravity of the powder is low and the density of the compact is low, making it difficult to obtain a high-density alumina pressureless sintered body. This is because if the average particle size is larger than 40 μm, the activity of the powder decreases and the sinterability deteriorates.

According to the present invention, the crystal structure of the silicon carbide powder is preferably β-type silicon carbide, and the crystal structure of the alumina powder is preferably α-type alumina.

According to the present invention, water or an organic solvent such as benzene, acetone, alcohol, trichlorethylene, toluene, or quintin, and if necessary, a dispersant are completely added to the composition mainly consisting of the silicon carbide powder or alumina powder, It is important to mix uniformly using one or more types of mixers such as a ball mill mixer, a vibration mill, a colloid mill, a Henschel mixer, and a high speed mixer. Furthermore, at the initial or mid-way stage of mixing, molding aids such as polyethylene glycol, polyvinyl urea! Addition of lecor, methylcellulose, chrycerin, starch, gum arabic, phenolic resin, carbowax, stearic acid, paraffin emafflesion, etc. improves moldability. Molding is carried out by, for example, pressure molding using a metal mold, rubber molding, injection molding, extrusion molding, armor molding, doctor blade method, calendar method, paper dipping method, etc., to obtain a desired molded product.

According to the present invention, the molded body contains hydrogen, humidified hydrogen, nitrogen,
Calcination can be carried out at normal pressure in an ambient atmosphere containing one or more gases of argon and helium, but humidified hydrogen is most preferred. In addition, Al2O, S10, C
It is preferable that one or more types of O gases be included. The reason is S ic+AIzoa→SiO+Al*O+
3iC and Al2O3 react due to the reaction of CO, but if the partial pressure of gases such as Al2O and 5i01GO is present in the atmosphere, the reaction between SiC and A120j is suppressed and the dense Si
This is because an alumina pressureless sintered body containing C can be obtained. Further, the molded body has a weight ratio of silicon carbide of 0.6 to 28.
It is possible to embed it in a mixture of 296 and alumina of 71.8 to 99.5% and fire it. The reason for this is that during firing, a reaction between silicon carbide and alumina occurs in the mixture of silicon carbide and alumina, gas of AIaOlSiOlCO is generated, and the reaction between SiC and Al2oz in the green body is suppressed, resulting in dense SiC. This is because it is easy and cheap to obtain.

According to this experiment, the molded body was heated at 1800 to 1900'C.
It is preferable to perform pressureless sintering in a temperature range of . The reason for this is that if the temperature is lower than 1800°C, the sinterability of the alumina powder and the silicon nitride powder is low and a sufficiently dense sintered body cannot be obtained. This is because the thermal conductivity of the alumina pressureless sintered body is greatly reduced due to the diffusion of
The temperature range is C.

Next, examples of the present invention will be described.

Example 1 β-type silicon carbide with an average particle size of 0.8 μm in a weight ratio of 0 to 20
% and α-type alumina with an average particle size of 0.4 μm in weight ratio of 78
~98% and average 4′x”tL 2.0 μm 5i02
Prepare 5 types of formulations with a weight ratio of 2%, and each formulation 1 (
To 10 g, 10 of water was added, 1 g of polyethylene glycol, 1 g of polyvinyl alcohol) and 0.5 g of stearic acid were added, and the mixture was heated in Po7 remill for 24 hours.
Mixed for an hour. The mixture was dried and granulated using a spray dryer, and the molding pressure was φ4 at 1.5 t/J using a molding method.
A molded body 1 of 0x5t was obtained. The compact was inserted into a tubular furnace and fired at a temperature of 1600"C for 1 hour in a humidified hydrogen stream to obtain an alumina atmospheric pressure sintered gold.

The bulk density of the sintered body thus obtained, the hardness measured by a micro Vickers hardness tester, the Kxo measured by the indenchysilon method, and the thermal conductivity measured by the laser crush method are shown in Table 1. Further, when the obtained sintered bodies were subjected to X-ray powder diffraction, it was found that β-type silicon carbide was contained in all the examples.

Comparative Example 1 β-type silicon carbide with an average particle size of 0.8 μm at a weight ratio of 50%, α-type alumina with an average particle size of 0.4 μm at a weight ratio of 48%, and 5iChe with an average particle size of 2.0 μm at a weight ratio of 2 Table 1 shows the results of pressureless sintering using the same method as in Example 1.

Example 2 5% by total weight of β-type silicon carbide with an average particle size of 0.8 μm and 90% by weight of α-type alumina with an average particle size of 0.4 μm
or 5i(h, M
4% formulation by weight of n O or MgO, respectively.
Various types were prepared, mixed, dried and molded in the same manner as in Example 1, and then fired in a humidified hydrogen stream at a temperature of 15006C for 2 hours to obtain an alumina atmospheric pressure sintered body. Table 2 shows the physical properties of the sintered body thus obtained.

Example 3 Table 8 shows the results when an alumina pressureless sintered body was obtained by reducing the average grain size and crystal structure of silicon carbide and the average grain size of alumina. The compositions of silicon carbide, alumina, and Kun 02 were constant at 2%, 96%, and 2% by weight, respectively, and the mixing, molding, and firing of the compounds were performed in the same manner as in Example 2.

Comparative Example 2 α-type silicon carbide with an average particle size of 108 m and an average particle size of 0.4
Table 8 shows the physical properties of an alumina pressureless sintered body sintered using μm α-type alumina.

Example 4 3% by weight of β-type silicon carbide with an average particle size of 0.8 μm, 94% by weight of α-type alumina with an average particle size of 0.4 μm, and 5i02' (i7) with an average particle size of 2.0 μm. 3% by weight
After preparing a mixture and molding it in the same manner as in Example 1, it was heated at 1500°C or 1600°C in a humidified hydrogen stream.
The physical properties of the alumina pressureless sintered body obtained by firing at °C for 1 hour are shown in Table 4.

Comparative Example 3 The same molded product as Example 4 was heated to 1250 ml in a humidified hydrogen stream.
Results of baking for 1 hour at a temperature of °C or 2000 °C Total 1
It is shown in Table 4.

Example 5 2% by weight of β-type silicon carbide with an average particle size of O, a μm, 96% by weight of α-type alumina with an average particle size of 0.04 μm, and 2% by weight of Sich with an average particle size of 2 μm. Table 5 shows the results of mixing and molding the mixture in the same manner as in Example 1, and then sintering the molded body in nitrogen, argon, a humidified hydrogen stream, and a mixture of alumina and silicon carbide.

Comparative Example 4 A molded body was obtained in the same manner as in Example 5, and then fired in an oxygen stream. Table 5 shows the results.

Table 1 (Note) KIc-Fracture resistance (Firing temperature 1600℃ in humidified hydrogen flow) Table 2 (Firing condition 1500℃ in humidified hydrogen flow) Table 3 (Firing condition 1500℃ in humidified hydrogen flow) Table 4 As is clear from the results in Table 5 and above, according to the present invention, the sintered body obtained by the pressureless sintering method in which silicon carbide is uniformly dispersed in the alumina sintered body is The excellent electrical properties of the alumina sintered body and the excellent thermal conductivity of the silicon carbide sintered body are combined, resulting in the excellent mechanical strength of both. It also has the following.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a flow sheet for producing an alumina sintered body containing silicon ash according to the present invention. Patent applicant IBIDEN Co., Ltd.

Claims (1)

[Scope of Claims] 1. A silicon carbide-containing alumina sintered body composed of a mixed composition containing 0.5 to 40% by weight of silicon carbide and the remainder being alumina as a main component. 2. Sin for 0.5 to 40% by weight of silicon carbide. MgO1Cab, SrO%BaO1M n Oz, Fe
d. Ti(h, ZrCh, P b O, Cr 20 s, B
Claim 1, characterized in that the mixture composition contains 0.1 to 20% by weight of one or more oxides of e203, and the remainder is alumina as a main component. The described sintered body. 3. The average particle size of the silicon carbide is 0.05 to 5.0 μm
The sintered body according to claim 1, characterized in that: 4. The sintered body according to claim 1, wherein the alumina has an average particle diameter of 0.5 to δO μm. 6. The sintered body according to claim 1, wherein the crystal structure of the alumina is α-type alumina. 7. Claim 1, characterized in that the silicon carbide is contained uniformly dispersed in the alumina sintered body.
The sintered body described in section. 8. The sintered body according to claim 1, wherein the silicon carbide-containing alumina sintered body has a bulk density of 90% or more of the theoretical density. 9. The β-type silicon carbide has an average particle size of 0.1 to 0.4μ!
n, containing at least 0.6 to 2.0% by weight, and the remainder having an average particle size of 1.0 to 1.
The sintered body according to claim 1, wherein the sintered body is made of a mixed composition containing α-type alumina having a diameter of 0 μm as a main component. 10. After uniformly mixing a composition mainly consisting of 0.5 to 40% by weight of silicon carbide powder and the remainder being alumina powder, and molding the homogeneous mixture thus obtained, the molded body was
A method for producing a silicon carbide-containing alumina sintered body, which comprises sintering under normal pressure at a temperature of 800 to 1900°C. 11. Silicon carbide powder 0.5-40% and 5i0 in terms of vehicle weight
2, MgO, Cab, 5rO1Bad, MnO2, Fe
01Ti(h, Z r O2, P b O%Cr 20
s, 0.1 to 0.1 of one type or a mixture of two or more of B2O3
11. The manufacturing method according to claim 10, characterized in that the composition consists of a composition mainly consisting of alumina powder, and the remainder being alumina powder. 12. The average particle size of the ashed silicon powder is 0.01 to 4.
0 μm, and the average particle size of alumina powder is 0.05 to 4
A patented silicon characterized by having a diameter of 0 μm,
11. The manufacturing method according to claim 10, wherein the crystal structure of the alumina powder is α-type alumina. 14. Add water or an organic solvent to the composition, and mix it with one or more of the following: a ball mill, an attriter, a homo mixer, a vibration mill, a colloid mill, a Henschel MIKI T-1 high 4-kisa-nato. 11. The manufacturing method according to claim 10, characterized in that uniform mixing is carried out using. 15. The manufacturing method according to claim 10, wherein the atmosphere during the pressureless sintering is one or more of hydrogen, humidified hydrogen, oxygen, argon, and helium. 16, fnI The atmosphere during pressureless sintering is AhOl.
11. The manufacturing method according to claim 10, which comprises one or more gases of SiOlCO. 17. The above-mentioned pressureless sintering is performed to form the compact into a silicon ash of 0.5 to 28.2% and alumina of 71.8 to 99.5% by weight.
11. The manufacturing method according to claim 10, characterized in that the method comprises embedding in a mixture of and firing.