JPS61178470A - Manufacture of high size-precision nitride sintered body andsame sintered body for heat-resistant tools - 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 method for manufacturing a nitride sintered body with excellent dimensional accuracy and a nitride sintered body for heat-resistant jigs with excellent dimensional accuracy, and particularly relates to The present invention enables the production of nitride sintered bodies suitable for applications requiring dimensional accuracy and strength at low cost and by sintering a formed body molded into a desired shape without substantially causing firing shrinkage. The present invention relates to a method for manufacturing a nitride sintered body with excellent dimensional accuracy that can be easily manufactured, and a heat-resistant nitride sintered body for a jig with excellent dimensional accuracy.

[Conventional technology]

Many nitride sintered bodies have excellent properties such as mechanical strength, heat resistance, and corrosion resistance, and are known to be used as high-temperature structural materials and corrosion- and wear-resistant materials.

Conventionally, methods such as pressure sintering, normal pressure sintering, and reaction sintering are known as methods for manufacturing nitride sintered bodies.

[Problem that the invention seeks to solve]

By the way, among these methods, according to the pressure sintering method and the pressureless sintering method, it is possible to obtain a sintered body with high density and high strength.
Both are sintering methods that involve large firing shrinkage during firing.
Since the dimensions of the sintered body are greatly affected by the firing shrinkage and the density of the formed body, it is extremely difficult to manufacture a sintered body with specific dimensional accuracy without special machining.

In addition, the reaction sintering method is a sintering method that does not cause much shrinkage during firing, but in the reaction sintering method, firing is performed by controlling the temperature and atmosphere so that the reaction temperature does not rise above the melting point of the metal element. This is important, and has the drawback that the firing time is extremely long.

As mentioned above, there has been no known method for manufacturing structural nitride sintered bodies requiring high dimensional accuracy at low cost and easily without special machining.

[Means for solving problems]

The present invention uses a sintering method different from the conventionally known sintering methods as described above, that is, a formed body formed into a desired shape is sintered without substantially causing firing shrinkage, thereby improving dimensional accuracy and strength. The purpose of this project is to provide a method for manufacturing structural nitride sintered bodies that require Develop a sintering method that can suppress firing shrinkage (as a result of various studies, we have found that by controlling the impurity components contained in nitride powder and sintering within a specific atmosphere and temperature range, The present invention has been completed by discovering a new method for manufacturing a nitride sintered body with excellent surface dimensional accuracy and high strength without causing significant firing shrinkage.

According to the present invention, a starting material mainly composed of nitride powder with an average particle size of 5 μm or less is formed into a green body, and then the green body is sintered in a non-acid style atmosphere without substantially shrinking. A method for producing a nitride sintered body with excellent dimensional accuracy, characterized by producing a nitride sintered body having an average bending strength of 2 kg/m1 or more, and a nitride sintered without substantially shrinking. Made of sintered body, average bending strength is 2
The above object can be achieved by a heat-resistant nitride sintered body for a jig with excellent dimensional accuracy characterized by A9/mm2 or more.

Next, the manufacturing method of the present invention will be explained in detail.

According to the present invention, the starting material mainly consisting of nitride powder is
It is necessary that the average particle size is 5 μm or less. The reason why the average grain size is limited to 5 μm or less is that if it is larger than 5 μm, there will be fewer bonding points between grains in the sintered body, which results in a high strength sintered body with a high strength, that is, an average bending strength of grade 5 or higher. This is because it not only becomes difficult to obtain a solid, but also the surface roughness deteriorates.

According to the present invention, various types of nitride powder can be used, but among them, a starting material is used for producing a nitride sintered body having excellent heat resistance, hardness, chemical stability, and electrical properties. It is preferable that the raw material contains at least one selected from boron nitride, aluminum nitride, and silicon nitride, and the total content thereof is 50 M'Ik% or more. Starting materials containing are preferred.

According to the present invention, it is preferable that the content of a substance that generates a liquid phase during sintering in the starting material is 5% by weight or less.

The reason is that the content of substances that generate a liquid phase during sintering is 5.
This is because if the amount is more than 1%, sintering shrinkage is likely to occur due to the action of the liquid phase during sintering.

According to the invention, the starting material is MyO1A120x,
Advantageously, the total content of CeO, Li2O, 8 ioz and Y2O3 is less than or equal to 3M%. The reason for this is that the above oxides are generally used as sintering aids when sintering nitrides at normal pressure, and if the total content is more than 3% by weight, they tend to shrink during firing (as a result, the dimensions This is because it becomes difficult to obtain a highly accurate sintered body.

According to the present invention, in order to obtain a sintered body with high dimensional accuracy, it is necessary to sinter without substantially shrinking, and the shrinkage rate at that time is preferably 2% or less, especially More preferably, it is 1% or less.

According to the present invention, it is advantageous to charge and fire the green body into a heat-resistant container in which the firing atmosphere can be controlled. The reason why it is advantageous to charge the formed body into a heat-resistant container and fire it while controlling the firing atmosphere is because it allows the necks between adjacent nitride particles to grow and form strong bonds. 6. As mentioned above, by charging the formed body into a heat-resistant container and firing it while controlling the firing atmosphere, necks between adjacent nitride particles can grow and they can be firmly bonded. The reason for this is the evaporation of nitride between nitride particles.
This is thought to be because mass transfer by recondensation and/or surface diffusion can be promoted.

According to the present invention, by charging the formed body into a heat-resistant container in which the firing atmosphere can be controlled and firing it, the volatilization rate of nitrides during firing is suppressed, and the volatilization rate is reduced to 5% by weight. % or less is advantageous.

According to the invention, said product form has at least 45% by volume
Advantageously, it has a density of . The reason for this is that when the density of the formed body is lower than 45% by volume, there are fewer points of contact between the nitride particles, which inevitably results in fewer bonding points, and the average of 2 kq//14 or more, which is the objective of the present invention, is reduced. This is because it is difficult to obtain a sintered body with bending strength.

According to the present invention, it is preferable that the nitrogen gas partial pressure in the non-oxidizing atmosphere is equal to or higher than the equilibrium pressure of nitride. The reason for this is that by making the nitrogen gas partial pressure equal to or higher than the equilibrium pressure of the nitride, neck growth can be promoted and the strength of the sintered body can be increased.

Next, the heat-resistant sintered nitride body for jig of the present invention will be explained in detail.

The heat-resistant nitride sintered body for a jig of the present invention must be made of a sintered nitride sintered body without substantially shrinking, and must have an average bending strength of 2 kQ/d or more. The reason for this is that although shrinkage during sintering is preferable in order to obtain a sintered body with high strength, the amount of shrinkage during sintering generally has a large effect on the density of the formed body, so it is important to ensure uniform shrinkage. In order to achieve this, it is important to obtain a formed body with a uniform density.However, it is extremely difficult to obtain a formed body with such a uniform density. This is because it is difficult to obtain a highly precise sintered body.Also, the reason why the average bending strength is limited to 2 kV- or more is that if the strength of the sintered body is lower than 2 kq/-, it may break or crack during use. This is because they are easily damaged and cannot withstand practical use.

In addition, it is advantageous that the sintering shrinkage rate of the nitride sintered body of the present invention, which is sintered without substantially shrinking, is 296 or less, and more preferably 196 or less.

The nitride sintered body as the nitride sintered body for heat-resistant jigs of the present invention can be made of deep nitrides, but among them, sintered bodies with excellent heat resistance, hardness, chemical stability, and electrical properties are used. For applications requiring solid bodies, it is preferable that at least 1 m of nitride selected from boron nitride, aluminum nitride, and silicon nitride is contained, and the total content is 50 ifi% or more.

The heat-resistant nitride sintered body for jig of the present invention is required to have extremely high dimensional accuracy and strength, and has an average grain size of 5.
It is preferable that the nitride sintered body is obtained by molding a starting material mainly composed of nitride powder of μm or less into a green body, and then sintering the green body in a non-oxidizing atmosphere.

The nitride sintered body for heat-resistant jigs of the present invention can be advantageously used as jigs for semiconductor heat treatment, insulating sleeves for heat-resistant parts such as heat-insulating fasteners and setters, heat-resistant/corrosion-resistant plates, and pulp/pump parts. I can do it.

Next, examples and comparative examples of the present invention will be described.

Example! 2 parts by weight of wax, 1 part by weight of polyethylene glycol, 0.5 parts by weight of stearic acid and 100 parts by weight of benzene are blended with 100 parts by weight of silicon nitride powder with an average particle size of 0.4 μm and a purity of 96% by weight, After mixing in a ball mill for 5 hours, it was spray dried.

The silicon nitride powder contains 2% by weight of oxygen, 1% by weight of carbon, 0.07% by weight of iron, 0.01% by weight of calcium, 0.2% by weight of aluminum, and 0.0% by weight of magnesium.
It contained osxtit%.

Collect an appropriate amount of this dried material and use a metal mold to
Molded at a pressure of t/d, diameter 40, thickness 5fi, density 1. A product form of '16f/cd (55% by volume) was obtained.

The formed body was placed in a graphite crucible and fired at a temperature of 1700'C for 1 hour in a nitrogen gas atmosphere under atmospheric pressure.

The density of the obtained sintered body is 1.76 fA, and the linear shrinkage rate of the formed body is 0.4 ± 0 in any direction.
．． The dimensional accuracy of the sintered body is within ±0.07%.
It was within 3111. Furthermore, when the average bending strength of this sintered body was measured, it was found to be as high as 6.3.

Example 2 The same operation as in Example 1 was repeated to obtain a sintered body.

The physical properties of the obtained sintered body are shown in Table 1.

As can be seen from the results shown in Table 1, the linear shrinkage rate is as small as 0.5% at maximum, and according to the sintering conditions shown in Example 1, the linear shrinkage rate was set to 0.4% and the formed shape was produced. It was confirmed that by molding and sintering, it is possible to easily produce a sintered body with extremely high dimensional accuracy.

Example 3 A sintered body was obtained in the same manner as in Example 1, except that silicon nitride powder having an average particle size of 4.1 μm was used. The physical properties of the obtained sintered body are shown in Table 1.

Comparative Example 1 A sintered body was obtained in the same manner as in Example 1, except that silicon nitride powder having an average particle size of 8.3 mm was used. The physical properties of the single sintered body obtained are shown in Table 1.

As can be seen from the results shown in Table 1, in the examples of the present invention, it was possible to easily produce a sintered body with a small linear shrinkage rate and its variation and excellent dimensional accuracy. On the other hand, when the silicon nitride powder of Comparative Example 1 with a large average particle diameter of 8.3 μm was used as a starting material, the linear shrinkage rate was 0.3 ±
Large variation of 0.3% and dimensional accuracy of ±0.1211
It dropped to 1.

Example 4 Same as Example 1, except that aluminum nitride powder with an average particle size of 0.8 μm and a purity of 97% by weight was used instead of silicon nitride powder, and a sintered body was obtained at a temperature of 1600°C. . Note that the aluminum nitride powder contains 0.16% by weight of carbon,
It contains 0.1% by weight of silicon, 0.09% by weight of iron, and 0.07% by weight of magnesium.

The physical properties of the obtained sintered body are shown in Table 1.

Example 5 Same as Example 1, except that boron nitride powder with an average particle size of 0.3 μm and a line spacing of 99.5% by weight was used instead of silicon nitride powder, and the sintered body was sintered at a temperature of 1400°C. I got it.

The physical properties of the obtained sintered body are shown in Table 1.

〔Effect of the invention〕

As described above, according to the present invention, a nitride sintered body with excellent dimensional accuracy can be obtained without substantially causing firing shrinkage, and it can be used as a structural material that requires dimensional accuracy and strength. Nitride sintered bodies can be provided at low cost without special machining.

Claims (1)

[Claims] 1. After forming a starting material mainly composed of nitride powder with an average particle size of 5 μm or less into a green body, the green body is sintered in a non-oxidizing atmosphere without substantially shrinking. 2 kg of knots
A method for producing a nitride sintered body with excellent dimensional accuracy, characterized by producing a nitride sintered body having an average bending strength of /mm^2 or more. 2. The manufacturing method according to claim 1, wherein the shrinkage rate of the sintered body due to sintering is 2% or less. 3. The starting material contains at least one selected from boron nitride, aluminum nitride, and silicon nitride,
The manufacturing method according to claim 1 or 2, wherein the total content thereof is 50% by weight or more. 4. The manufacturing method according to any one of claims 1 to 3, wherein the starting material contains at least 50% by weight of silicon nitride. 5. The manufacturing method according to any one of claims 1 to 4, wherein the starting material has a content of 5% by weight or less of a substance that generates a liquid phase during sintering. 6. The manufacturing method according to any one of claims 1 to 5, wherein the nitrogen gas partial pressure in the non-oxidizing atmosphere is equal to or higher than the equilibrium pressure of the nitride. 7. A heat-resistant jig nitride with excellent dimensional accuracy, which is made of a nitride sintered body sintered without substantially shrinking, and has an average bending strength of 5 kg/mm^2 or more. Sintered body. 8. The nitride sintered body contains at least one selected from boron nitride, aluminum nitride, and silicon nitride, and the total content thereof is 50% by weight or more. Nitride sintered body for heat-resistant jigs. 9. The nitride sintered body is obtained by forming a starting material mainly composed of nitride powder with an average particle size of 5 μm or less into a green body, and then sintering the green body in a non-oxidizing atmosphere. A nitride sintered body for a heat-resistant jig according to claim 7 or 8.