JP2009057215A - Joined article and its producing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joined article having satisfactory airtightness while assuring the function of a porous article even when a large-scale porous article having a large pore diameter and high porosity is used. <P>SOLUTION: The joined article comprises an SiC porous article, a penetrating layer where metal silicon is penetrated in the SiC porous body and a joining layer consisting of a silicon alloy contacting with the penetrating layer, and has an aluminum content in the silicon alloy of 1-20 wt.%. It is characterized that the aluminum content in the metal silicon in the penetrating layer is not more than that in the silicon alloy. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to various industrial fields using porous bodies including honeycombs used in automobile exhaust gas treatment apparatuses, catalyst carriers and filters used under corrosion, and semiconductor manufacturing apparatuses.

SiC is excellent in heat resistance and corrosion resistance, and is used as a member for semiconductor manufacturing equipment and automobile parts. Since SiC has a high sintering temperature and the atmosphere is carried out under an inert gas, the size is limited and it is difficult to produce a complex shape product. In order to solve such a problem, various joining techniques have been proposed. What is particularly problematic in bonding is the residual stress due to the difference in thermal expansion from the bonding material. When the residual stress is large, there arises a problem that residual strain is generated after bonding and the strength of the bonded portion is lowered. In order to solve this problem, metallic silicon having a thermal expansion coefficient close to that of SiC has been used as a bonding material. Metallic silicon is a material that can be easily obtained in a variety of shapes, such as powder and thin plates, and because it joins with a mechanism that reacts with the carbon remaining on the SiC surface to form SiC, the thermal expansion difference is further alleviated. It is suitable for bonding SiC because it is easy.

In recent years, the use of SiC as a semiconductor manufacturing apparatus member and automobile parts has further expanded, and the demand for a porous body as well as a dense sintered body of SiC has increased. SiC porous bodies are excellent in heat resistance and corrosion resistance, and are therefore used as catalyst carriers and filters. The use range is wide, and various shapes of SiC porous bodies are required.

However, there is a limit to the shape of SiC porous bodies that can be manufactured in the same manner as dense bodies, and joining of SiC porous bodies and joining with SiC dense bodies are indispensable for producing desired shapes.

Various joining techniques relating to such SiC porous bodies have been proposed. For example, Patent Document 1 discloses a ceramic member made of two substrates made of a plurality of ceramic / metal composites in which open pores of a porous body made of silicon-containing ceramic are impregnated with metal silicon. The base materials are bonded to each other through a bonding layer made of metal silicon.
JP 2002-11653 A

As described above, metal silicon not only has a small difference in thermal expansion from SiC, but also reacts with residual carbon on the surface of SiC, so that it has good wettability and exhibits its properties well as a bonding material. However, in the case of a SiC porous body, since a large amount of residual carbon is also present inside the porous body, the metal silicon of the bonding material does not stay only on the bonding surface, but excessively penetrates into the porous body, filling the pores. There was a case. Therefore, it was difficult to secure a sufficient flow rate because it was not possible to secure a sufficient communication portion such as when used as a filter. In particular, when the pore size of the SiC porous body is large, the penetration of metallic silicon as a bonding material easily proceeds, so that the pore portion is filled with metallic silicon, and conversely, the amount of metallic silicon in the bonding portion becomes insufficient, resulting in the bonding strength and bonding. In some cases, airtightness at the part could not be obtained. Therefore, it was impossible to join a porous body having a large pore diameter or a high porosity with metallic silicon in order to flow a large flow rate.

In particular, when joining a large SiC porous body, the heat capacity is large, so that the holding time at a high temperature is longer than that of a small product. Therefore, when metal silicon is used as the bonding material, there is a problem that the metal silicon volatilizes and excessively enters the porous body.

Furthermore, some semiconductor manufacturing apparatus members composed of joined bodies in which porous bodies are joined together have different atmospheres on both sides separated by the joining layer, or supply and exhaust air with the joining layer interposed therebetween. The airtightness of the department is very important. Therefore, not only the bonding strength but also the demand for airtightness is severe, and it has been a challenge to increase this.

In the present invention, even when a large porous body having a large pore diameter and a high porosity is used, a bonded body having sufficient airtightness while ensuring the function of the porous body and a method for producing the same are provided.

In order to solve these problems, the present inventors provide a portion having a high SiC filling rate in a SiC porous body, infiltrate metal silicon into that portion, form an infiltration layer, and then process the infiltration layer By controlling the thickness of the material and further adding aluminum to the metal silicon of the bonding material to lower the melting point, the volatilization of the metal silicon of the permeation layer is reduced, and the metal silicon excessively penetrates the SiC porous body. As a result, the inventors have found a method for joining while suppressing the occurrence of the present invention.

That is, the present invention is a joined body including a SiC porous body, a permeation layer in which metallic silicon penetrates the SiC porous body, and a joining layer made of a silicon alloy in contact with the permeation layer, the aluminum alloy of the silicon alloy The present invention provides a joined body having a content of 1 to 20 wt%.

Usually, when aluminum is added to metal silicon and heated and melted and then cooled, it shrinks when solidifying, which causes a so-called shrinkage nest (gap) in the bonding layer, resulting in a decrease in airtightness. In order to prevent this, the following method is used in the present invention. First, when the bonding material melts at the time of bonding, it comes into contact with the metal silicon of the permeation layer. Accordingly, diffusion of aluminum in the bonding material occurs, and the proportion of aluminum in the entire bonding material is reduced as compared with that before bonding. Therefore, even if aluminum is added to lower the melting point of the bonding material, the shrinkage of solidification can be kept small, and shrinkage can be reduced. Moreover, since the metal silicon of the permeation layer has a low bonding temperature, it does not melt and can suppress excessive penetration into the porous body. Thereby, even if it applies to a large sized product with long holding time of junction maximum temperature, volatilization of metallic silicon is controlled and excessive penetration of metallic silicon into a SiC porous body can be controlled.

The aluminum content of the silicon alloy of the bonding layer in the present invention is preferably 1 to 20 wt%. The aluminum contained in the silicon alloy is less than the amount added as a bonding material. This is because it diffuses into the metal silicon of the permeation layer. Moreover, it is because aluminum volatilizes at the time of heating and melting. When the aluminum content of the silicon alloy is within the above range, bonding can be performed at an appropriate bonding temperature, and generation of shrinkage cavities due to solidification shrinkage of the bonding layer can be suppressed.

Further, the present invention is characterized in that the metal silicon of the permeation layer contains aluminum not more than the aluminum content of the silicon alloy.

The metal silicon in the permeation layer contains aluminum that is less than or equal to the aluminum content of the silicon alloy in the bonding layer. The aluminum in the bonding material diffuses into the metal silicon in the permeation layer, but diffuses throughout the permeation layer. Even if it is, it is equivalent to the aluminum content of the joining layer, and when it penetrates a part near the joining surface of the permeation layer, the aluminum content of the metal silicon of the permeation layer is less than the aluminum content of the joining layer. is there. As described above, with such a configuration, it is possible to obtain a bonded body in which the generation of shrinkage nests is suppressed.

Furthermore, the present invention is characterized in that the thickness of the permeation layer is 50 μm or less.

Unreacted carbon and a binder for producing a porous body remain on the surface of ordinary SiC. Metallic silicon reacts easily with carbon to form SiC. Metal silicon permeates into the SiC porous body by the reaction energy at that time. Although the penetration of metal silicon can be suppressed to some extent by improving the wettability of SiC and metal silicon, it has been difficult to control the penetration distance of metal silicon to be short. Therefore, in the present invention, the thickness of the permeation layer of the porous body in the joined body is reduced to 50 μm or less by once penetrating metal silicon into the porous body to form a permeation layer and reducing the thickness of the metal silicon permeation layer by processing. This is what we can do. If the thickness of the osmotic layer is 50 μm or less, it becomes easy to exert the function of the porous body regardless of the size and shape of the porous body, and it can be applied to various products. Although the minimum of the thickness of a osmosis | permeation layer is not specifically limited, It is preferable that it is 20 micrometers or more. When the bonding material penetrates into the porous body at least about 20 μm, it can be firmly bonded by the anchor effect.

Moreover, it is preferable that the porosity of a SiC porous body is 40% or more. The SiC porous body of the present invention has a porosity capable of securing a sufficient flow rate when used as a catalyst carrier, a filter, etc., and the function of the porous body is reduced by reducing the thickness of the permeation layer as described above. It is possible to obtain a joined body that can exhibit the above.

The SiC filling rate of the permeation layer into which metallic silicon has penetrated is larger than the SiC filling rate of the porous body (100-porosity (%) of the porous body), and the specific filling rate is preferably 50% or more. 60% or more is more preferable. By increasing the SiC filling rate of the permeation layer, it is possible to prevent excessive metal silicon from penetrating into the porous body, and even when a porous body having a high porosity and a high porosity is used, its function A joined body can be obtained without impairing the resistance. Although the upper limit of the SiC filling rate of the osmotic layer is not particularly limited, it can be practically increased to 70%.

Moreover, in this invention, the joined body whose thickness of a joining layer is 100 micrometers or less can be obtained. In the joined body of the present invention, since excessive metal silicon permeation into the porous body is suppressed, it is possible to join with good airtightness even if the thickness of the joining layer is small. Therefore, it is possible to obtain a joined body with few portions of the permeation layer and the joining layer that do not function as a porous body.

The joined body of the present invention includes a step of allowing metal silicon to permeate at least part of the SiC porous body to form a permeation layer, a step of processing the permeation layer to a thickness of 50 μm or less, and forming a joining surface; A bonding material obtained by adding 5 to 30 wt% of aluminum to metal silicon is heated to a temperature equal to or lower than the melting point of the metal silicon and the bonding material melts, whereby the aluminum contained in the bonding material is converted into the metal silicon of the permeation layer. And a step of diffusing in a bonded structure.

As described above, when bonding SiC porous bodies using metal silicon, metal silicon permeates into the porous body, so that it was difficult to form a bonded body while maintaining the function as the porous body. However, it has been found that the permeation distance can be controlled by forming a metal silicon permeation layer and processing the permeation layer to 50 μm or less to form a joint surface.

The amount of aluminum added to the bonding material is preferably in the range of 5 to 30 wt%. When the addition amount is less than 5 wt%, the melting point of the bonding material cannot be lowered sufficiently, and there is a possibility that the metal silicon in the permeation layer of the SiC porous body may volatilize, thereby causing a connection portion of the SiC porous body. Metallic silicon invades. In addition, when the addition amount is more than 30 wt%, the aluminum concentration is not sufficiently lowered even if aluminum diffusion occurs due to the above mechanism, and the influence of solidification shrinkage is strongly generated, and the shrinkage nest generated in the joint causes airtightness. Problems arise in properties and strength.

The present invention also includes a step of impregnating at least a part of the SiC porous body with a slurry of SiC powder to form an impregnated portion, and a step of infiltrating the metal impregnated portion into the impregnated portion to form an infiltrated layer. And a method for producing a joined body.

When metal silicon is infiltrated, fine SiC powder is impregnated on the joint surface of the porous body to form an impregnated portion, and the filling rate of SiC is increased. Therefore, as a matter of course, the SiC filling rate of the impregnated portion is larger than the SiC filling rate of the porous body. This prevents metal silicon as a bonding material from penetrating into the porous body excessively.
The SiC filling rate of the impregnated part is preferably 50% or more, and more preferably 60% or more. This is because if the filling rate is less than 50%, the penetration of metallic silicon cannot be sufficiently prevented, and the metallic silicon may penetrate into the entire porous body.

In this way, by forming an impregnated portion having an increased SiC filling rate at the joint surface of the SiC porous body and allowing the metal silicon to permeate the portion once, excessive permeation of the metal silicon can be prevented.

Furthermore, in the present invention, since the permeation layer is processed to a thickness of 50 μm or less to form a joining surface, a joined body with few permeation layer portions that do not function as a porous body can be obtained.

As described above, a portion having a high SiC filling rate is provided in the SiC porous body, and metal silicon is infiltrated into the portion to form a permeation layer, and then the permeation layer is processed, and the thickness is controlled and bonded. Accordingly, even when a porous body having a large pore diameter and a high porosity is used, a joined body can be obtained that is joined while sufficiently ensuring the function of the porous body.

As the SiC porous body of the present invention, those having a porosity of 40% or more are preferably used. If the porosity is 40% or more, it can function as a porous body such as a catalyst carrier or a filter. The upper limit of the porosity is not particularly limited, but is preferably 70% or less. A porous body having a porosity of more than 70% is not preferable because the strength of the porous body itself is significantly reduced. Moreover, as for the pore diameter of a SiC porous body, 10-100 micrometers is preferable. If it is such a range, it can be made to function suitably as porous bodies, such as a catalyst support | carrier and a filter.

As the SiC porous body, one produced by a known manufacturing method can be used. For example, it can be obtained by a method of sintering a powder obtained by adding a pore former to SiC powder, or a method of making metal silicon permeate a resin porous body such as polyurethane.

The fine SiC powder impregnated in the SiC porous body is preferably one having an average particle diameter of 5 μm or less. If a particle having a particle size in such a range is used, the SiC porous body having the above pore diameter can be appropriately impregnated.

As a method of impregnating the slurry of SiC powder, it may be applied to the surface on which the impregnated portion is to be formed with a brush or the like, or may be immersed in the slurry by a predetermined depth. About the thickness of an impregnation part, it can adjust with the viscosity of slurry, the frequency | count of application | coating, immersion depth, etc.

As the form of metallic silicon and aluminum as the bonding material, powder, plate, foil or the like can be used. You may use what added the resin binder to the metal silicon powder and the aluminum powder, and shape | molded in the sheet form.

Various methods can be employed for processing the joint surface depending on the shape of the joined body to be manufactured, such as surface grinding or a machining center.

The infiltration of the metal silicon is preferably performed at 1410 to 1500 ° C. under vacuum or inert gas. If the melting point of the metallic silicon is 1410 ° C. or lower, the metallic silicon does not melt and cannot penetrate. Moreover, since the volatilization of metallic silicon is remarkable at 1500 ° C. or higher, it is not preferable.

Heating at the time of bonding is preferably performed at 1270 to 1390 ° C. under vacuum or inert gas. This is a suitable temperature range when joining using the joining material to which aluminum in the predetermined range of the present invention is added, and excessive penetration of metal silicon into the porous body occurs within this temperature range. It becomes possible to join.

Hereinafter, the present invention will be described with reference to examples and comparative examples.
[Examples 1 to 10, Comparative Examples 1 to 4]
A SiC porous body having a porosity of 65% and an average pore diameter of 30 μm was used. These shapes are disk shapes of Φ200 mm × t15 mm. In addition, a SiC dense body (relative density 98%) having the same shape and a porous body were also joined. The porosity was determined by the Archimedes method, and the average pore diameter was determined by the mercury intrusion method.

The impregnation of the SiC porous body with the SiC porous body was performed by preparing a slurry obtained by adding isopropyl alcohol to a commercially available SiC powder and applying this to the joint surface of the SiC porous body. The SiC powder used has an average particle size of 3.4 μm. After applying the SiC powder, it was dried at 100 ° C. for 5 hours. The average particle size (d50) is a measured value using a laser diffraction / scattering particle size distribution meter (LA-920 manufactured by Horiba, Ltd. (registered trademark)).

The penetration of metallic silicon (purity 99.99%) into the SiC powder-impregnated portion was performed using a vacuum carbon furnace in Ar at 1450 ° C. to 1.5 hr (temperature increase rate 100 ° C./hr). .

Separately, metallic silicon was completely infiltrated into a 50 × 50 × t3 porous body impregnated with SiC powder to the inside of the porous body, and the filling rate of SiC was determined from the density. Based on the above, it was assumed that the SiC filling rate of the permeation layer in the joined body was 60% or more.

The joint surface was processed by grinding a porous metal silicon permeation layer using a # 600 grindstone and setting the average thickness of the permeation layer to 20 to 40 μm.

Bonding is performed by dry-mixing metal silicon powder (purity 99.99%) and aluminum powder (purity 99.9%) with the addition amount shown in Table 1, and using a sheet of 300 μm thickness solidified with an organic binder as a bonding material. Bonding was performed in Ar under the conditions shown in Table 1. Regarding the bonding temperature, the melting point changes depending on the amount of aluminum added, and this is taken into account. However, the melting point of metal silicon was 1414 ° C., and the bonding temperature was lower than this. Further, a load was applied so that the bonding was performed satisfactorily. Specifically, 2000 g of a SiC sintered body was placed.

<Evaluation method>
For the evaluation after bonding, the thickness of the permeation layer was observed with a microscope, and the average value was evaluated. In addition, about the thickness of the osmosis | permeation layer, in the case of porous bodies, the average of the osmosis | permeation layer thickness of both porous bodies was used. In addition, the evaluation of the shrinkage nest state is performed by observing the cut surface of the joined body divided into quarters for each joined body, and with respect to the length of the joining layer (100 mm × 4 locations) appearing on the cut surface. When the length of the gap is 10% or less, it is marked as ◯, when it is 20% or less, Δ, and when it is larger than 20%, it is marked as x. As for this evaluation value, it was confirmed by a gas leak test conducted in advance that the leakage from the joint is not problematic if the length of the gap generated in the joint layer is 20% or less. Judged. Further, the aluminum content of the bonding layer was measured using a calibration curve from elemental mapping by an X-ray microanalyzer (EPMA).

The thicknesses of the osmotic layers in Examples 1 to 10 were all 50 μm or less. Also, in the shrinkage state, all the evaluations for the aluminum addition amount of 20 wt% or less were ◯. When it became 25-30 wt%, the shrinkage nest increased slightly, but it was 20% or less which is the reference value of Δ. In addition, when it observed about the thickness of the joining layer of Examples 1-10, all joined bodies were 100 micrometers or less.

In Comparative Examples 1 and 2 with a small aluminum content, the thickness of the permeation layer was 100 μm or more, and a larger amount of metal silicon entered the porous body than in the Examples. When the gap was examined by observing the shrinkage state, the effect of the shrinkage nest was small because the amount of aluminum added was small, but a large amount of gaps were generated because a large amount of metal silicon that should originally be in the bonding layer entered the porous body. It was. Further, in Comparative Examples 3 and 4 having a large aluminum content, the thickness of the permeation layer was small, but a shrinkage nest was generated by 20% or more, resulting in a problem of airtightness.

As described above, by forming a permeation layer of metallic silicon having a predetermined thickness on the SiC porous body, and then forming and bonding a bonding layer made of a silicon alloy containing a predetermined aluminum, the pore diameter is large and the porosity is Even when a high porous body was used, it was confirmed that a bonded body excellent in airtightness could be obtained while sufficiently securing the function of the porous body.

Claims (5)

A joined body comprising a SiC porous body, a permeation layer in which metallic silicon permeates the SiC porous body, and a joining layer made of a silicon alloy in contact with the permeation layer, wherein the silicon alloy has an aluminum content of 1 to 1 A joined body characterized by being 20 wt%. The joined body according to claim 1, wherein the metal silicon of the permeation layer contains aluminum having an aluminum content equal to or less than that of the silicon alloy. The joined body according to claim 1, wherein a thickness of the permeation layer is 50 μm or less. Infiltrating metal silicon into at least part of the SiC porous body to form a permeation layer;
Processing the permeation layer to a thickness of 50 μm or less to form a joint surface;
A bonding material obtained by adding 5 to 30 wt% of aluminum to metal silicon is heated to a temperature equal to or lower than the melting point of the metal silicon and the bonding material is melted. Diffusing into
The manufacturing method of the conjugate | zygote characterized by including. A step of impregnating at least a part of the SiC porous body with a slurry of SiC powder to form an impregnated portion;
A step of infiltrating the metal silicon into the impregnated portion to form a permeation layer;
The manufacturing method of the conjugate | zygote of Claim 4 containing this.