JP2015224153A - Method for producing silicon carbide sintered compact - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a silicon carbide sintered compact capable of improving plasma resistance while using a normal pressure sintering method.SOLUTION: There is provided a method for producing a silicon carbide sintered compact which comprises: a step of preparing a slurry by mixing a sintering aid and a solvent; a step of preparing a dried product by drying the slurry; a step of preparing an SiC powder by pulverizing the dried product; and a step of obtaining SiC granules by sieving the SiC powder using a sieve having a roughness of 100 μm or more and 300 μm or less; and a step of sintering the SiC granules at normal pressures.

Description

  The present invention relates to a method for manufacturing a silicon carbide sintered body that manufactures a silicon carbide sintered body by a normal pressure sintering method.

  Conventionally, various manufacturing methods have been proposed as a method for manufacturing a silicon carbide sintered body containing silicon carbide. Generally, a slurry is prepared by mixing a sintering aid or the like with silicon carbide particles (hereinafter, SiC particles) having an average primary particle size of 0.01 to 10 μm, and the slurry is dried by spray drying. By doing so, granules of SiC particles are produced. Subsequently, a silicon carbide sintered body is manufactured by putting granules of SiC particles in a mold and pressurizing and heating the granules of SiC particles in the mold (for example, Patent Document 1).

JP 2011-256062 A

  As described above, the granules of SiC particles produced by spray drying have a spherical shape, and when the granules of SiC particles are added, the fluidity of the granules is high.

  By the way, as mentioned above, it is conceivable to heat the granules of SiC particles while applying pressure, but there are limitations on the degree of molding freedom and a great cost burden.

  On the other hand, it is conceivable to sinter the SiC particle granules by the normal pressure sintering method. However, since the SiC particle granules obtained by spray drying described above have the same particle size, they are sintered by the normal pressure sintering method. As a result, gaps are likely to occur between the SiC particles. Accordingly, fine concave portions (bore) are easily formed on the surface of the silicon carbide sintered body, and the plasma resistance of the silicon carbide sintered body is lowered.

  Therefore, the present invention has been made to solve the above-described problems, and a method for producing a silicon carbide sintered body that can improve plasma resistance while using an atmospheric pressure sintering method. The purpose is to provide.

  The first feature is a method for producing a silicon carbide sintered body containing silicon carbide, wherein a slurry is prepared by mixing the silicon carbide, a sintering aid and a solvent, and the slurry is dried. The step of producing a dried body by the step, the step of producing SiC granules by pulverizing the dried body, and sieving the SiC granules by using a sieve having a roughness of 100 μm or more and 300 μm or less. The gist is to include a step of obtaining and a step of sintering the SiC granule at normal pressure.

  1st characteristic WHEREIN: The average particle diameter of the said SiC granule is 50 micrometers or more and 90 micrometers or less.

  1st characteristic WHEREIN: The particle size distribution (D90 / D10) of the said SiC granule is 6-12.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the silicon carbide sintered compact which can aim at the improvement of plasma tolerance can be provided, using an atmospheric pressure sintering method.

FIG. 1 is a flowchart showing a method for manufacturing a silicon carbide sintered body according to the first embodiment. FIG. 2 is a diagram for explaining the evaluation results.

  Below, the manufacturing method of the silicon carbide sintered compact which concerns on embodiment of this invention is demonstrated, referring drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals.

  However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

[Outline of Embodiment]
The method for producing a silicon carbide sintered body according to the embodiment is a method for producing a silicon carbide sintered body containing silicon carbide. The manufacturing method includes a step of producing a slurry by mixing the silicon carbide, a sintering aid and a solvent, a step of producing a dry body by drying the slurry, and a SiC by grinding the dry body. A step of producing powder, a step of obtaining SiC granules by sieving the SiC powder using a sieve having a roughness of 100 μm or more and 300 μm or less, a step of sintering the SiC granules at normal pressure, Is provided.

  In the embodiment, by sieving the SiC powder using a sieve having a roughness of 100 μm or more and 300 μm or less, the SiC granule is sintered at normal pressure by intentionally varying the particle size of the SiC granule. In this case, SiC granules having a small particle size enter between SiC granules having a large particle size. Accordingly, a silicon carbide sintered body having few pores (bore, etc.) can be obtained while using the atmospheric pressure sintering method, and the plasma resistance of the silicon carbide sintered body is improved.

[First Embodiment]
(Configuration of method for producing silicon carbide sintered body)
Below, the manufacturing method of the silicon carbide sintered compact which concerns on 1st Embodiment is demonstrated. FIG. 1 is a flowchart showing a method for manufacturing a silicon carbide sintered body according to the first embodiment.

  As shown in FIG. 1, the method for manufacturing a silicon carbide sintered body includes a slurry preparation step S10, a drying step S20, a powder preparation step S30, a sieving step S40, and a sintering step S50.

  Step S10 is a step of preparing a slurry by mixing silicon carbide, a sintering aid and a solvent. The silicon carbide, the sintering aid and the solvent are mixed and dispersed for 16 hours by a ball mill, for example.

  Specifically, as the silicon carbide, α-type silicon carbide, β-type silicon carbide, amorphous silicon carbide, or a mixture thereof can be used. The silicon carbide may be a commercially available product. The average particle diameter of silicon carbide is 0.01 μm or more and 10 μm or less. Silicon carbide (precursor) can be produced, for example, by the method disclosed in JP-A-10-120411.

As the sintering aid, boron carbide (B ₄ C) or carbon black (C) can be used.

  As the solvent, water, lower alcohols such as ethyl alcohol, ethyl ether or acetone can be used. As the solvent, a solvent having a low impurity content is preferably used.

  In step S10, Cresolve may be used as a dispersion medium in addition to silicon carbide, a sintering aid and a solvent.

  Step S20 is a step of producing a dried body by drying the slurry. For example, the slurry is dried by, for example, heat drying using a hot plate to obtain a block-shaped dry body. The heating temperature of the hot plate is 115 ° C., for example.

  Step S30 is a step of producing SiC powder by pulverizing the dried body. The pulverization step of the dried body is not particularly limited.

  Step S40 is a step of obtaining SiC granules by sieving the SiC powder using a sieve having a roughness of 100 μm or more and 300 μm or less. The sieving is performed using, for example, nylon conforming to JIS Z 8801.

  Here, the average particle size of the SiC granules after sieving is preferably 50 μm or more and 90 μm or less. The particle size distribution (D90 / D10) of the SiC granules after sieving is preferably 6-12. The particle size distribution (D90 / D10) is a ratio of 90% cumulative diameter (D90) and 10 [%] cumulative diameter (D10) calculated from the particle size distribution of the powder.

  Step S50 is a step of sintering the SiC granules at normal pressure. Specifically, the SiC granule obtained in step S40 is placed in a mold, and the SiC granule is pressed by a uniaxial press, and then added to the SiC granule by cold isostatic pressing (CIP). By pressing, a molded body of silicon carbide is obtained. The pressure applied by the uniaxial press is 40 MPa, for example. The pressure applied by the cold isostatic pressing method is, for example, 150 MPa. Subsequently, the compact is put into a graphite crucible and the compact is sintered.

(Function and effect)
In the first embodiment, by sieving the SiC powder using a sieve having a roughness of 100 μm or more and 300 μm or less, the SiC granule is at atmospheric pressure by deliberately giving variation in the particle size of the SiC granule. When sintered, SiC granules having a small particle size enter between SiC granules having a large particle size. Accordingly, a silicon carbide sintered body having few pores can be obtained while using the atmospheric pressure sintering method, and the plasma resistance of the silicon carbide sintered body is improved.

[Evaluation results]
Hereinafter, the evaluation results will be described. In the evaluation results, samples according to Comparative Examples 1 and 2 and Example 1-3 were prepared, and product performance, porosity, bulk density, and plasma resistance were measured.

In Comparative Examples 1 and 2 and Example 1-3, slurry was produced under the following conditions. Specifically, 100 g of silicon carbide, 0.8 g of boron carbide (B ₄ C), 2 g of carbon black (C), and 100 g of Cresolve were mixed and dispersed using a ball mill for 16 hours.

  Thereafter, in Comparative Example 1, the slurry was dried using a spray drying method in SiC granulation. On the other hand, in Example 1-3 and Comparative Example 2, after drying the slurry using a hot plate under a temperature condition of 115 ° C., the dried body obtained by drying was pulverized.

  After that, in Comparative Examples 1 and 2 and Example 1-3, SiC granules were obtained by sieving the granulated SiC powder using a mesh-size sieve shown in FIG.

  In Comparative Examples 1 and 2 and Example 1-3, the average particle size and particle size distribution (D90 / D10) of the SiC granules after sieving were as shown in FIG.

  After that, in Comparative Examples 1 and 2 and Example 1-3, the SiC granules were put into a mold, pressed after uniaxial pressing at a pressure of 40 MPa, and then added to the SiC granules by CIP treatment at a pressure of 150 MPa. Pressed. Subsequently, the compact was put in a graphite crucible and the compact was sintered. The sintering conditions are as shown below.

Room temperature to 1200 ° C. Temperature rising condition = 200 ° C./hr, atmosphere ... vacuum 1200 ° C. to 2100 ° C .: Temperature rising condition = 100 ° C./hr, atmosphere ... Ar × 2 ml / min
2100 ° C.:…atmosphere…Ar×2 ml / min
2100 ° C. to room temperature: temperature reduction condition: natural temperature drop, atmosphere ... Ar × 2 ml / min
For each sample, the density and porosity were measured using the Archimedes method. In addition, plasma resistance was measured by irradiating plasma for 5 hours using a plasma generator. The evaluation results of each characteristic are as shown in FIG.

Bulk density: Archimedes method
Plasma resistance: Plasma generator made by Denki Giken
Output power 500W, pressure 50Pa, CF4 / O2 = 100 / 100sccm, amount of wear after 5 hours As shown in FIG. It was confirmed that That is, while producing SiC powder through the drying step (S20) and the powder production step (S30), and sieving the SiC powder using a sieve having a roughness of 100 μm or more and 300 μm or less, atmospheric pressure firing is performed. While using the sintering method, it was confirmed that a silicon carbide sintered body having few pores can be obtained and the plasma resistance of the silicon carbide sintered body can be improved.

[Other Embodiments]
Although the present invention has been described with reference to the above-described embodiments, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

Claims (3)

A method for producing a silicon carbide sintered body containing silicon carbide,
Producing a slurry by mixing the silicon carbide, sintering aid and solvent;
Producing a dried body by drying the slurry;
Producing SiC powder by pulverizing the dried body;
Obtaining SiC granules by sieving the SiC powder using a sieve having a roughness of 100 μm or more and 300 μm or less;
A method for producing a silicon carbide sintered body comprising a step of sintering the SiC granule at normal pressure.   The method for producing a silicon carbide sintered body according to claim 1, wherein an average particle diameter of the SiC granule is 50 μm or more and 90 μm or less.   The method for producing a silicon carbide sintered body according to claim 1, wherein a particle size distribution (D90 / D10) of the SiC granule is 6 to 12.

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