JP2001278685A - Silicon carbide material and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon carbide material, which is hardly reacted with heat-treated materials and is lightweight and of which ceramic-sprayed film is hardly stripped. SOLUTION: In manufacturing the silicon carbide material, a ceramic-sprayed film 4 with multiple layers, of which the outside layer is the zirconia ceramic- sprayed film, is formed on part or all of surface 3 of a substrate 2. The substrate 2 is made of atmospheric pressure sintering silicon carbide with porosity of 0.1% or less and central line average height in roughness (Ra) of 3-15 μm at the surface 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon carbide member having a ceramic sprayed coating, and more particularly to a silicon carbide member suitable for a jig used when heat-treating an electronic component in a non-oxidizing atmosphere.

[0002]

2. Description of the Related Art In a heat treatment process for electronic components such as ceramic capacitors, a heat treatment jig sprayed with zirconia, alumina, spinel, or the like, which has the least reaction at a contact portion with the capacitor, is used. , Alumina-silica, silicon carbide, and the like are used.

The thickness of a conventional heat treatment jig is about 5 to 5 mm.
Although the thickness is 10 mm, it is desired to improve the productivity by reducing the thickness to 4 mm or less to increase the number of stacks in the heat treatment step of a capacitor or the like.

[0004] Therefore, among the conventionally used materials of the base material, by using a normal pressure silicon carbide sintered body having a porosity of 0.1% or less as the base material, it is possible to achieve high strength and a thin wall. Since this substrate has few open pores on the surface and has a center line average roughness of about Ra = 0.1 μm, even if it is used as a jig for heat treatment even if it is sprayed as it is, the film peels off. There is a drawback that the service life is not sufficient.

As a countermeasure against this, Japanese Patent Laid-Open Publication No.
In Japanese Patent Application Laid-Open Publication No. H11-264, a proposal is made to improve the adhesion of a coating layer by modifying the surface of a ceramic substrate. The specific means of the present invention is that the center line average roughness is Ra = 0.1
It is disclosed that by roughening the surface to 5 μm or more, the adhesion of the coating layer can be improved. However, in the present invention, the center line average roughness is only studied up to Ra = 2.85 μm, and when used as a jig for heat treatment of an electronic component, a sufficient peeling prevention effect of the film cannot be obtained.

Japanese Patent Application Laid-Open No. 11-263671 discloses a porous ceramic sprayed film having a porosity of 12% or more by water plasma spraying on a base layer of a porous alumina-silica or SiC based sintered body. A ceramic sprayed film having a porosity of 7% or less on the surface layer by gas plasma spraying;
A firing tool with a ceramic spray coating comprising layers is described. However, since the firing tool material has a relatively dense structure in which the contact surface with the object to be fired is relatively dense, the contact area with the object to be fired becomes large, and the reaction cannot be sufficiently suppressed.
Sufficient weight reduction cannot be expected.

[0007]

Accordingly, there has been a demand for a silicon carbide member which is less likely to react with the object to be heat-treated, is lighter in weight, and is less likely to peel off the ceramic sprayed coating.

[0008] The present invention has been made in view of the above circumstances, it is difficult to react with the object to be heat-treated, the weight is reduced,
Further, it is an object of the present invention to provide a silicon carbide member in which a ceramic sprayed coating is difficult to peel off.

[0009]

Means for Solving the Problems According to the first aspect of the present invention, which has been made to achieve the above object, the porosity is 0.1% or less and the surface has a center line average roughness (Ra) of 3 to 15 μm. It has a roughened normal pressure sintered silicon carbide substrate, and a plurality of ceramic sprayed coating layers formed on part or all of the surface of the substrate, and the outermost layer of the ceramic sprayed coating is zirconia. The gist of the present invention is a silicon carbide member characterized by being a thermal sprayed coating.

In the invention of claim 2 of the present application, the sprayed zirconia coating is zirconia stabilized or partially stabilized by at least one selected from calcia, magnesia, and yttria, or a mixture of stabilized zirconia and unstable zirconia. The gist is a silicon carbide member according to claim 1, which is made of a mixture.

[0011] In the third aspect of the present invention, the normal pressure sintered silicon carbide sintered body has a bulk density of 3.05 g / cm ³ or more and a three-point bending strength at room temperature of 380 MPa or more. It is a gist of the silicon carbide sintered member according to claim 1 or 2.

[0012] The invention of claim 4 of the present application is to form an underlayer of a plasma sprayed layer made of alumina or mullite by gas plasma spraying on a part or the whole surface of the normal pressure sintered silicon carbide sintered body. A method for producing a silicon carbide sintered member, characterized by forming a surface layer composed of one or more of unstable, calcia partially stable, and yttria partially stable zirconia on the underlayer by water plasma spraying. The gist is that there is.

In the invention of claim 5 of the present application, the ten-point average roughness (Ra) of the surface of the sintered body on which the underlayer is formed is Rz ≧ 2.
The gist of the invention is a method of manufacturing a silicon carbide member according to claim 4, wherein the thickness is 0 μm.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a silicon carbide member according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, the silicon carbide member has a porosity of 0.1% or less and a surface having a center line average roughness (Ra) of 3 or less.
Substrate 2 made of atmospheric pressure sintered silicon carbide roughened to a thickness of 15 μm
And a plurality of layers formed on the surface 3 of the substrate 2, for example, 2
And the outermost layer 5 of the ceramic sprayed coating 4 is a zirconia ceramic sprayed coating, and the underlayer 6 formed on the substrate 2 is a mullite sprayed coating.

The thermal spray coating of the zirconia ceramic of the outermost layer (surface layer) 5 is composed of stabilized zirconia, partially stabilized zirconia, or stabilized zirconia stabilized by at least one selected from calcia, magnesia, and yttria. Consists of a mixture with stabilized zirconia.

The undercoat layer 6 is preferably a mullite sprayed coating, but when three ceramic sprayed coatings are used, the underlayer is made of Al ₂ O ₃ and the intermediate layer formed between this underlayer and the outermost layer is formed. It may be mullite.

Next, a method for manufacturing a silicon carbide member will be described.

The silicon carbide member is manufactured by using a generally used manufacturing method. A silicon resin and a thermosetting resin are added to a mixture of a SiC raw material having a plurality of particle sizes and a B-based compound as a sintering aid. Are added, mixed, pressed, and fired to obtain a fired body of normal pressure sintered silicon carbide having a porosity of 0.1% or less. The bulk density of the fired body is 3.05 g /
In m ³ or more, and is at room temperature bending strength is 380MPa or more. Accordingly, when used as a shelf jig, high-temperature strength and bend resistance can be obtained and the thickness can be reduced. If the bulk density is less than 3.05 g / m ³ , the high temperature strength and the bend resistance are inferior, so that sufficient durability cannot be obtained.

At least one surface of the fired body on which the object to be heat-treated is placed is subjected to, for example, sandblasting or alkali etching so that the arithmetic average roughness Ra is in a specific range, that is, Ra = 3 to 15 μm. The surface is roughened. Most preferably, Ra = 10 to 15 μm.
The ten-point average roughness is Rz ≧ 20 μm. Ra = 1
To roughen to 0 to 15 μm and Rz ≧ 20 μm,
Sand blasting is preferably performed in a green state before firing.

By setting the average roughness R in the range of 3 to 15 μm, the transmission of thermal stress due to the temperature difference during use can be reduced, and the generation of cracks and cracks can be suppressed. Improve reliability and life. In addition, the surface of the member is roughened on one surface or the entire surface, and sintering is performed after the surface is roughened. Since fine cracks formed during the surface roughening disappear due to grain growth during sintering, the surface is roughened. A decrease in strength due to the formation can be suppressed.

When Ra is smaller than 3 μm, the number of usable times until the zirconia layer (outermost layer) is peeled off becomes small, and it is difficult to put the zirconia layer to practical use when used as a heat treatment jig.

The roughening of the sintered body of normal pressure sintered silicon carbide by sandblasting or alkali etching
It is difficult to exceed 5 μm, especially larger than 20 μm. The reason for this is that, unlike normal pressure sintered silicon carbide, which has very small open pores on the surface with a porosity of 0.1% or less, is different from refractory silicon carbide materials that have open pores, and is first sprayed by roughening. Although it is possible to form a film, the granulated particle size of silicon carbide is about several μm, and if the surface is roughened for a long time, the particles will peel off together, making it extremely difficult to partially dig deep. Because it is. On the other hand, if it exceeds 15 μm, the strength of the base material decreases, and if it exceeds 20 μm, there is a possibility that the base material itself may be cracked by the heating / cooling cycle.

When the surface roughness of the substrate is Rz ≧ 20 μm, a sufficient anchor effect on the sprayed film can be obtained, and the peeling resistance of the sprayed film can be improved. Rz <20μ
If m, a sufficient anchor effect on the sprayed film cannot be obtained, and the sprayed film is easily peeled.

Thereafter, a plurality of thermal spray coatings are formed on one surface by thermal spraying. For example, a mullite sprayed coating is formed as an underlayer on one surface by gas plasma spraying in an argon atmosphere, and a zirconia sprayed coating is formed thereon by water plasma spraying.

The sintered body of the normal pressure sintered silicon carbide has a flexural strength at room temperature of about 400 MPa, and has a reduced thickness by using the normal pressure sintered silicon carbide as a heat treatment jig base. 4
mm or less. The fired body contains about 95% silicon carbide, and a B-based compound is used as a sintering aid, but any type of sintering aid may be used.

The underlayer is a thermal spray coating of mullite, Al ₂ O ₃ or the like. Mullite has excellent creep resistance, and most preferably, has a mullite composition (3Al ₂ O ₃ .2SiO
₂ , Al ₂ O ₃ = 71.8% by weight). However, since non-mullite SiO ₂ is included in the production method of the mullite raw material, the creep resistance is improved when a current commercially available raw material is used. Preferably has Al ₂ O ₃ of 72 to 85
%, Most preferably 74-78% by weight. The thickness of the underlayer differs depending on the shape of the jig for heat treatment and the material type of the base, but if it is 0.05 mm or more, the effect of improving the creep resistance can be obtained. If the thickness is too large, the creep resistance is improved.

The outermost layer is a zirconia ceramic sprayed material comprising stabilized zirconia stabilized by at least one selected from calcia, magnesia, and yttria, partially stabilized zirconia, or a mixture of stabilized zirconia and unstabilized zirconia. It is a coating.

The properties required for the outermost layer are difficulty in reacting with the object to be heat-treated and durability (peeling, falling off). By using zirconia as the outermost layer, the reaction with the object to be heat-treated can be minimized.

In the conventional case where the zirconia layer is a single-layer film, even if the substrate is roughened, the difference in thermal expansion coefficient between the normal pressure sintered silicon carbide substrate and the zirconia layer causes the jig to be used as a heat treatment jig. The service life cannot be endured due to peeling of the coating.

As for the peeling of the outermost layer, which is a drawback of the coated product, it is possible to obtain a film which is hard to peel by using a thermal spraying method. The coating sprayed by the plasma spraying method has a low elastic modulus, a small generation of thermal stress due to expansion and contraction, dispersion of stress, relaxation of expansion itself, and other effects hardly cause peeling. In particular, when the surface layer is water plasma, the reaction area can be suppressed because the contact area with the object to be fired is small and the particle diameter of the sprayed material is large. On the other hand, when both the underlayer and the surface layer are formed by water plasma spraying, the porosity is relatively large,
The components in the material to be fired penetrate into the thermal spray layer, while the base material is extremely dense, so that the thermal spray layer that accumulates at the interface between the base material and the thermal spray layer and is physically adhered is easily peeled off.

The heat treatment jig as described above has a large flexural strength since the porosity of the substrate is 0.1% or more, and a flexural strength at room temperature with a density of 3.05 g / m ³ or more. 38
Since it is 0 MPa or more, when it is used as a shelf jig, high-temperature strength and bend resistance can be obtained and the thickness can be reduced. By forming an underlayer mainly composed of mullite or the like having excellent creep resistance on the surface of the base material, it is possible to improve the creep resistance while maintaining the thermal shock resistance, and to reduce the thickness. The surface of the inner coating layer is coated with zirconia or zirconate, which is hardly reactive with the object to be heat-treated, so that the outermost layer is formed. It is possible to provide a heat treatment jig capable of coping with firing of a product.

Further, even if the thickness is reduced, warping hardly occurs during use, and high durability and an improvement in throughput of a firing process by expanding a loading space for a heat treatment object, and energy saving by light weight and low heat capacity of a heat treatment jig are possible. It became.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Test 1 "1" Purpose: A film peeling test was performed on a sample in which a base layer and an outermost layer having the materials shown in Table 1 were formed on a substrate shown below using the method for manufacturing a silicon carbide member according to the present invention. A reactivity test with an object to be heated was performed.

"2" sample: (1) Base material Examples 1 to 8 and Comparative examples 1 to 7 The size was 200 mm × 350 mm, the thickness was 3.5 mm, the material was 98% by weight of SiC, and the bulk density was 3.15 kg / cm. ³
Pressure-sintered silicon carbide material having a three-point bending strength of about 400 MPa at room temperature.

Comparative Example 8 The dimensions were the same as in the above, and the material was 94% by weight of SiC,
Density 2.5kg / cm ³Degree, room temperature 3-point bending strength 25M
It is a silicon carbide sintered body of about Pa.

(2) Roughening Examples 1 to 8 and Comparative Examples 1 to 4 In a mixed alkaline solution of sodium hydroxide and sodium nitrate heated to about 500 ° C. (weight ratio: NaOH / NaNO)
₃ = 5: 1 to 6: 1), the etching process is performed by changing the etching time, and the Ra value is changed.
The surface was roughened to a Ra value as shown in Tables 1 and 2.

Comparative Examples 6 and 7 The surface was roughened to a Ra value as shown in Table 2 by sandblasting.

(3) Formation of Thermal Spray Coating Examples 1 to 8 and Comparative Examples 1 to 4, 6 to 8 The materials shown in Tables 1 and 2 were subjected to gas plasma spraying.
A thermal spray coating was formed by spraying only one surface of the sample. At this time, the thickness of the thermal spray coating (from the base layer to the surface layer) was 200 to 300 μm.

[3] Test method: (1) Using an electric furnace as shown in FIG.
Heat to 1400 ° C, hold at 1400 ° C for 2 hours, and then cool to room temperature multiple times in heating and cooling cycles (up to 15 times)
The number of times until the zirconia layer (outermost layer) was peeled was examined.

(2) The reactivity between the ceramic capacitor, which is the object to be heat-treated, and the sample was examined using an actual machine.

"4" Test results: Tables 1 and 2 show the results.

[0043]

[Table 1]

[0044]

[Table 2]

Example 1 (Ra = 10 μm): No peeling of zirconia layer, no reactivity with ceramic capacitor,
Most stable.

Example 2 (Ra = 3 μm): Although not as good as Example 1, the number of times until the zirconia layer was peeled was 13 times, which is significantly improved as compared with the conventional example, and the reaction with the ceramic capacitor was also improved. There is no sex. Number of times until peeling is 13
Since the number of times is more than the number of times, it can be considered that the device can be used for the actual machine. Therefore, it was confirmed that the surface roughness should be Ra = 3 μm or more.

Example 3 (Ra = 5 μm): Although not equal to Example 1, the number of times until the zirconia layer was peeled was 14 times, which was superior to Example 2, and was significantly improved as compared with the conventional example. And no reactivity with ceramic capacitors.

Example 4 (Ra = 15 μm): Neither peeling of the zirconia layer nor reactivity with the ceramic capacitor was observed.
However, when the strength of the substrate of Example 4 was measured, it was found that the strength was reduced by about 40% as compared with that before the surface roughening. If the roughening is promoted, the sprayed coating becomes difficult to peel off, but at the same time, the strength of the base material decreases and cracks easily occur,
It was confirmed that the surface roughness did not need to exceed Ra = 15.

Example 5 (Ra = 10 μm): Example 1
Similarly using a base material and, Al ₂ O ₃ underlying layer of mullite
However, there is no separation of the zirconia layer and no reactivity with the ceramic capacitor, and it is stable as in Example 1. It has been confirmed that the underlayer should be made of a material that is substantially the same as mullite and does not react with silicon carbide.

Example 6: A substrate was used in the same manner as in Example 1, and the zirconia-stabilizing material was changed to 8% of yttria of Example 1.
Although the stabilization was changed to 4% partial stabilization of yttria, the outermost zirconia layer did not peel off and did not react with the ceramic capacitor, and was stable as in Example 1.

Example 7: Calcia was changed to 4% partial stabilization in the same manner. However, there was no separation of the outermost zirconia layer and no reactivity with the ceramic capacitor.

Example 8: Similarly, the magnesia was changed to 4% partial stabilization, but the outermost zirconia layer was not peeled off, and there was no reactivity with the ceramic capacitor.

In Examples 6 to 8, peeling tests and reactivity investigations were conducted on substrates using various stabilizers of zirconia. Example 1 using 8% yttria of the stabilizer was used.
Since there was no problem similarly to the above, it was confirmed that it was not necessary to particularly limit the type of the stabilizing material.

Example 9 In Example 1, Al ₂ O ₃ was coated as a base layer between the substrate and mullite to form three layers. However, there was no peeling of the zirconia layer and no reactivity with the ceramic capacitor. It is stable as in Example 1. It was confirmed that the number of layers of the thermal sprayed layer does not need to be particularly limited as long as the underlayer is formed.

In addition to the stabilized zirconia and the partially stabilized zirconia, a mixture of stabilized zirconia and unstabilized zirconia exhibited the same effect as in Example 1.

Comparative Example 1 (Ra = 1 μm): The same substrate as in Example 1 was used, and the surface roughness was Ra = 1 μm.
The number of times until the zirconia layer is peeled off is as extremely low as one time, which is not practical.

Comparative Example 2 (Ra = 2 μm): Similarly, the surface roughness was set to Ra = 2 μm, but the number of times until the zirconia layer was peeled was as low as 6 times, making it difficult to be put to practical use.

Comparative Example 3 (Ra = 20 μm): Similarly, the surface roughness was set to Ra = 20 μm, but the number of times until the zirconia layer was peeled was extremely low as one, and cracks also occurred in the substrate itself. , Not practical.

COMPARATIVE EXAMPLE 4 A zirconia layer was formed directly on a substrate using the same substrate as in Example 1 without forming an underlayer, but the number of times until the zirconia layer was peeled was extremely low at one time. Not practical.

Comparative Example 5: The sintered substrate itself was used, and no surface roughening and no film formation were performed. There is a reaction with the object to be heated, and it is not practical.

Comparative Example 6 Using the substrate used in Example 1, a single layer of a mullite film was formed on the substrate. There is a reaction with the object to be heated, and it is not practical.

Comparative Example 7 Similarly, a single layer of an Al ₂ O ₃ film was formed on a substrate. There is a reaction with the object to be heated, and it is not practical.

Comparative Example 8: In Example 7, the substrate was changed from a normal pressure sintered silicon carbide sintered body to a refractory silicon carbide sintered body. The number of times until the zirconia layer is removed is as low as 3 times,
Not practical. The refractory silicon carbide sintered body was made of coarse particles and had a porosity of 15%. In the peel test, in addition to peeling, the substrate itself warped and cracked.

2. Test 2 "1" Purpose: A test similar to Test 1 was performed using the materials shown in Tables 3 and 4 and the conditions for forming the underlayer and the surface layer.

"2" Test results: Tables 3 and 4 show the results.

[0066]

[Table 3]

[0067]

[Table 4]

It was found that all of Examples 10 to 14 had excellent peeling resistance and reaction resistance.

On the other hand, Comparative Examples 9 and 11 had no problem with the reaction resistance, but had a problem with the peeling resistance. Comparative Examples 10 and 12 had no problem with the peeling resistance. It was found that there was a problem in the properties and it could not be put to practical use.

3. Test 3 "1" Purpose: As shown in FIG. 3, the bulk specific gravity, room temperature three-point bending strength and surface roughness Ra of the normal pressure sintered silicon carbide substrate used for the silicon carbide member according to the present invention were changed. The presence or absence of cracks is examined using a simple heat cycle test device.

"2" Sample: The materials of Examples 15 to 25 and Comparative Examples 13 to 21 are normal pressure sintered silicon carbide materials of about 95% of SiC. This material is about 97% silicon carbide, and boron and carbon (BC) are used as sintering aids. The production method is a commercially available purity of about 9
9%, SiC powder having a specific surface area of about 15 m ² / g and 0.3 mass% of B4C having an average particle size of about 2.5 μm as a sintering aid.
(However, only Comparative Example 18 was 0.2%), 8.5% by mass of a phenol resin (resole type) having a residual carbon content of about 50% by mass was added, and wet-pulverized and mixed in ethanol for 24 hours.
The slurry is spray-dried to an average particle size of about 8
After granulating to 0 μm, molding pressure was about 2
A molded body of 35 × 4 mm was obtained. Regarding the molding pressure, numerical values are changed for each of the examples and comparative examples.

The molded body was cured at 200 ° C. for 12 hours, and then subjected to sand blasting (abrasive SiC # 60) to obtain the surface roughness (firing) of Examples 15 to 25 and Comparative Examples 13 to 21 shown in Tables 5 to 7 below. (After consolidation). (However, the surface was roughened after firing only in Comparative Example 16.) Thereafter, it was filled in a carbon case and sintered at 220 ° C. for 2 hours. The atmosphere during sintering is from room temperature to 1400 ° C.
Until the above, the vacuum was set in consideration of the thermal decomposition of the phenolic resin, and thereafter, it was set in an argon atmosphere at normal pressure.

The bulk density of the obtained silicon carbide sintered body was determined by JI
After measurement according to S R1634, JIS R1601
Bending test piece (3 × 4 × 40 mm, C0.2)
Were prepared, and the three-point bending strength at room temperature was measured.

The conditions for measuring the center line average roughness are as follows:
8 mm and a cutoff value of 0.8 mm.

For Comparative Examples 19 to 21, those actually used as firing jigs such as capacitors were obtained. All were molded and processed into a 200 × 200 × t3.5 plate shape.

The material of Comparative Example 19 was 94% SiC, bulk density was about 2.5 g / cm ³ , and three-point bending strength at room temperature was 25 MPa.
Of silicon carbide.

The material of Comparative Example 20 was Al ₂ O ₃ 72%, S
iO ₂ 26%, bulk density 2.65 g / cm ³ ,
It is an alumina / silica material having a three-point bending strength of about 9 MPa at room temperature.

The material of Comparative Example 21 was about 95% ZrO ₂ ,
It is a zirconia material having a CaO partial stability, a bulk density of about 4.3 g / cm ³ and a three-point bending strength of about 25 MPa at room temperature.

Examples 15 to 25 and Comparative Examples 13 to 2
In order to investigate the occurrence of cracks during firing of a capacitor or the like when the firing jig 1 is thinned, 200 × 200 × t
Samples of Examples 15 to 25 and Comparative Examples 1 to 21 which were formed and processed into a 3.5-plate shape were heated to 1400 ° C. in the air.
After holding at 1400 ° C. for 2 hours, a heating / cooling cycle of cooling to room temperature was performed a plurality of times (up to 15 times), and the number of times of occurrence of cracks was examined. The setter mounted on the sample is made of zirconia (size: 50 × 50 × t3). (However, in Comparative Example 21, a zirconia setter was not placed during the heating / cooling cycle test).

"3" Test results: Tables 5 to 7 show the results.

[0081]

[Table 5]

[0082]

[Table 6]

[0083]

[Table 7]

In Examples 15 to 25, the surface roughness Ra = 3 to
15 μm, bulk density 3.05 g / cm ³ or more, room temperature 3
The point bending strength was 380 MPa or more, and no cracks were observed in any of the heating / cooling cycle tests.

On the other hand, as in Comparative Examples 13 and 14, when Ra = 0.2 μm and 2 μm, cracks occurred at the number of heating and cooling cycles of 4 and 7 times.

In Comparative Example 16, the surface was roughened at the time of sintering, but cracks were generated after four heating / cooling cycles.

In Comparative Example 17, cracks occurred in the twelfth heating / cooling cycle because of the low bulk density of the sintered body. This is considered to be because the open porosity is high when the density is low, so that the area where the material is continuously oxidized in the heating / cooling cycle increases, and the strength decreases remarkably as the number of cycles increases.

In Comparative Example 18, since the amount of the sintering aid was smaller than the predetermined amount, the bending strength was low and the heating and cooling cycle 8
Cracks occurred on the second round.

Comparative Examples 19 to 21 verify whether or not the conventional material can be made thinner. When the thickness is set to 3.5 mm, each of the materials has a heating / cooling cycle of 1 to 4 times.
Peeling occurred.

[0090]

According to the silicon carbide member and the method of manufacturing the same according to the present invention, it is possible to provide a silicon carbide member which is less likely to react with an object to be heat-treated, is reduced in weight, and hardly peels off the ceramic sprayed coating. it can.

That is, a substrate made of normal pressure sintered silicon carbide having a porosity of 0.1% or less and having a surface roughened to a center line average roughness (Ra) of 3 to 15 μm; A plurality of ceramic sprayed coatings formed on part or all of the surface, the outermost layer is a zirconia ceramic sprayed coating,
By setting Ra to a specific range, the zirconia layer does not peel even after repeated use, has a long service life, can directly mount the object to be heat-treated, and can cope with firing of various objects to be heat-treated. A silicon carbide member suitable for a jig can be provided. Furthermore, even if the thickness is reduced, warpage is less likely to occur during use. High durability and increased throughput of the baking process by expanding the loading space for heat treatment objects, and light weight of heat treatment jigs and energy saving by low heat capacity are possible. .

The zirconia ceramic sprayed coating may be made of stabilized zirconia stabilized by at least one selected from calcia, magnesia, and yttria, partially stabilized zirconia, or a mixture of stabilized zirconia and unstabilized zirconia. Therefore, there is provided a heat treatment jig which is difficult to react with a heat treatment object, can directly mount the heat treatment object on a heat treatment jig, and can cope with firing of various heat treatment objects. Can be.

Since the normal pressure sintered silicon carbide sintered body has a bulk density of 3.05 g / cm ³ or more and a three-point bending strength at room temperature of 380 MPa or more, it is used as a shelf plate jig. In this case, high-temperature strength and bend resistance can be obtained, and the thickness can be reduced.

Further, an underlayer of a plasma sprayed layer made of alumina or mullite is formed on a part or the entire surface of the normal pressure sintered silicon carbide sintered body by gas plasma spraying. Since it is a manufacturing method of forming a surface layer composed of one or more of unstable, calcia partially stable, and yttria partially stable zirconia by water plasma spraying, the contact area with an object to be fired is reduced, and the sprayed material is formed. Has a large particle size, it is possible to manufacture a silicon carbide member in which the reaction is suppressed.

Further, since the ten-point average roughness (Rz) of the surface of the sintered body on which the underlayer is formed is Rz ≧ 20 μm, a sufficient anchor effect on the sprayed film is obtained, and the peeling resistance of the sprayed film is reduced. An improved silicon carbide member can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a silicon carbide member according to the present invention.

FIG. 2 is a schematic diagram of an electric furnace used for Test 1 in Examples.

FIG. 3 is a schematic diagram of an electric furnace (heat cycle test device) used for Test 3 in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat treatment jig 2 Substrate 3 Surface 4 Ceramic spray coating 5 Outermost layer 6 Underlayer

Claims (5)

[Claims] 1. A substrate made of normal pressure sintered silicon carbide having a porosity of 0.1% or less and having a surface roughened to a center line average roughness (Ra) of 3 to 15 μm, and a surface of the substrate. And a plurality of ceramic sprayed coating layers formed on a part or all of the ceramic sprayed coating, and the outermost layer of the ceramic sprayed coating is a zirconia sprayed coating. 2. The zirconia sprayed coating is calcia,
The silicon carbide member according to claim 1, comprising zirconia stabilized or partially stabilized by at least one selected from magnesia and yttria, or a mixture of stabilized zirconia and unstable zirconia. 3. The normal pressure sintered silicon carbide sintered body has a bulk density of 3.05 g / cm ³ or more and a three-point bending strength at room temperature of 380 MPa or more. 3. The sintered silicon carbide member according to 1 or 2. 4. A method for forming alumina or gas on a part or the entire surface of a normal pressure sintered silicon carbide sintered body by gas plasma spraying.
A base layer of a plasma sprayed layer made of mullite is formed, and further, the base layer is not stable by water plasma spraying,
A method for producing a silicon carbide sintered member, comprising forming a surface layer made of one or more of calcia partially stable and yttria partially stable zirconia. 5. The method for producing a silicon carbide member according to claim 4, wherein the ten-point average roughness (Rz) of the surface of the sintered body on which the underlayer is formed is Rz ≧ 20 μm.