JP6000299B2 - Method for producing inner container for reaction vessel - Google Patents

Description

  The present invention relates to an inner container for placing in a reaction chamber of a reaction container, and more particularly to an inner container formed of silver or a silver alloy and having a joint portion joined by friction stir welding.

  When recycling waste plastics such as polyvinyl chloride, polytetrafluoroethylene, and polyethylene terephthalate, material recycling that recycles waste plastic into plastic raw materials or products, chemical recycling that chemically decomposes and recycles waste plastic into chemical raw materials, Alternatively, there is thermal recycling in which waste plastic is incinerated to recover thermal energy or used as a solid fuel. Of these, thermal recycling accounts for the majority.

  However, since hazardous substances such as dioxins are generated during incineration, high-temperature incineration facilities or appropriate exhaust gas treatment facilities are required. In addition, generation of environmentally hazardous substances due to an increase in carbon dioxide is a problem.

  On the other hand, in recent years, a decomposition reaction technique using supercritical water has been developed and actively used. According to this technology, it is possible to oxidize, hydrolyze, or thermally decompose atmospheric pollutants such as dioxins and hazardous wastes such as PCBs, making it possible to make hazardous wastes harmless and to recycle various wastes. It is.

  However, corrosive liquids such as hydrogen chloride and hydrofluoric acid are generated during the pyrolysis process. Since these corrosive liquids corrode the reaction vessel, the inner surface of the reaction vessel was lined with a noble metal such as platinum for the purpose of protecting the reaction vessel (see, for example, Patent Document 1).

  Furthermore, there is silver as a material having excellent corrosion resistance, and it has been shown that coating by silver plating or the like is effective (for example, see Patent Document 2).

  By the way, the technique of the friction stir welding method is disclosed as a metal joining method (for example, refer patent document 3 or 4). The present applicant has proposed a friction stir welding method for platinum or a platinum-based alloy having a high melting point (see, for example, Patent Document 5). Further, a friction stir welding tool capable of friction stir welding of a high melting point member such as platinum, a platinum base alloy, or stainless steel has been proposed (see, for example, Patent Document 6 or 7).

JP 2001-170478 A JP 2012-205976 A JP 7-505090 Gazette Japanese National Patent Publication No. 9-508073 Japanese Patent Laid-Open No. 2004-090050 JP 2006-320958 A Japanese Patent No. 4047371

  However, the technique of Patent Document 1 has a problem in that the precious metal such as platinum is expensive in itself, so that the reaction vessel is also expensive, and as a result, the cost for decomposing the waste plastic is also expensive.

  The technique of Patent Document 2 has an advantage that silver is cheaper than platinum, but the silver plating layer peels off from the base member due to repeated expansion and contraction and corrodes the base member. There was a problem.

  In order to solve such a problem in Patent Document 2, it is desired that a monolithic capsule without joints is placed in a reaction vessel using silver or a silver alloy, and the reaction proceeds in the capsule. Alternatively, it is desired that the inner wall of the reaction vessel is lined with silver or a silver alloy and the reaction proceeds in that. However, the lining of the integrally formed capsule and the inner wall of the reaction vessel is not only difficult to manufacture, but also has a problem that the material yield is poor and it is difficult to process into a complicated shape. Even if cheaper silver is used, the manufacturing cost is greatly increased.

  On the other hand, in order to reduce the manufacturing cost, it is conceivable to use a joining technique instead of the integral molding process. However, since silver or a silver alloy has a high thermal conductivity, problems such as the occurrence of blowholes and the occurrence of weld cracks occur depending on the alloy elements added in the conventional fusion welding method, and it is difficult to obtain a sound joint. Further, in the melt welding method, the structural change and the evaporation of the alloy components occur, so that the mechanical characteristics are deteriorated, and the structure is damaged and the corrosive substance is leaked.

  Accordingly, an object of the present invention is to provide a reaction formed of silver or a silver alloy in which no blowholes and weld cracks are generated in the joint portion, and no deterioration of mechanical properties due to structural change and evaporation of alloy components occurs. It is to provide an inner container for the container.

According to the present invention, there is provided a method for manufacturing an inner container for a reaction container, wherein the inner container is made of silver or a silver alloy for containing a raw material for reaction, which is disposed inside a reaction chamber of the reaction container. Alternatively, the inner container is formed using a rolled base material made of a silver alloy containing 50% by mass or more of silver, and a joining portion of the inner container is joined by friction stir welding. To do.

In the manufacturing method of the internal container for reaction containers which concerns on this invention, the form in which the said internal container has comprised the shape of the capsule is contained.

In the method for producing an internal container for a reaction container according to the present invention, when the internal container is disposed inside the reaction chamber, a portion of 50% or more of the outer wall surface of the internal container is the inner wall surface of the reaction chamber. The form which has a shape which touches is included. An inner container sized to substantially contact the inner wall of the reaction container can play a role similar to a silver or silver alloy lining. Furthermore, in the method for manufacturing an internal container for a reaction container according to the present invention, a base is disposed between the bottom surface of the reaction chamber of the reaction container and the bottom surface on the outside of the internal container.

  Since the inner vessel for the reaction vessel of the present invention is joined by friction stir welding, blowholes and weld cracks do not occur in the joined portion as when the fusion welding method is applied, and the alloy components Since no evaporation occurs, fluctuations in the alloy components can be suppressed and the corrosion resistance of the material can be maintained. Further, in the friction stir welding, since the crystal grains are made finer, a high-strength bonding portion is obtained, and as a result, the mechanical characteristics of the inner container are not deteriorated.

It is the schematic which shows one form of the mechanism of a friction stir welding method. It is the schematic of the 1st reaction container used by this invention. It is the schematic of the 2nd reaction container used by this invention. An image of the appearance of the joined product of Example 1 and the joined product of Comparative Example 1 is shown. An entire cross-sectional image, a joint enlarged image, and a base material enlarged image of the joined product of Example 1 are shown. An entire cross-sectional image, a joint enlarged image, and a base material enlarged image of the joined product of Example 2 are shown. An entire cross-sectional image, a joint enlarged image, and a base material enlarged image of the joined product of Comparative Example 1 are shown. An entire cross-sectional image, a joint enlarged image, and a base material enlarged image of the joined product of Comparative Example 2 are shown. It is a graph which shows the result of the tensile test of as FSWed. It is a graph which shows the result of the tensile test of as annealed.

  Next, although an embodiment is shown and explained in detail about the present invention, the present invention is limited to these descriptions and is not interpreted. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

  The inner container for the reaction container according to the present embodiment is arranged inside the reaction chamber of the reaction container, and the inner container is made of silver or a silver alloy in the inner container for containing the raw material for the reaction. The joined portion of the inner container is joined by friction stir welding.

  The reaction vessel is preferably a reaction vessel used in a supercritical hydrolytic decomposition treatment apparatus or a hydrothermal synthesis treatment apparatus, and the structural form is not particularly limited, but is a vessel type or a coil type. For example, the form of the reaction vessel 10 shown in FIG. 2 or FIG. 3 may be used. The reaction vessel may be any material that can withstand pressure, and is made of a heat-resistant alloy such as low alloy steel or nickel chromium alloy.

  The inner container is disposed inside the reaction chamber of the reaction container and accommodates raw materials for the reaction. Here, as a form example in which the inner container has a capsule shape, for example, the capsule 20 shown in FIG. The wall thickness of the inner container is, for example, 0.1 to 5 mm, and preferably 0.5 to 3 mm. In FIG. 2, the base 22 is disposed between them in order to prevent adhesion between the bottom surface of the reaction chamber of the reaction vessel 10 and the bottom surface outside the capsule 20. The base 22 may be a solid part, a hollow part, or a cylindrical part. The material of the base 22 may be any material that can withstand pressure, and is made of a heat-resistant alloy such as low alloy steel or nickel chrome alloy.

  Another form of the inner container is a form in which 50% or more of the outer wall surface of the inner container is in contact with the inner wall surface of the reaction chamber when placed inside the reaction chamber. For example, the inner container 30 shown in FIG. Although the inner container 30 is not a coating lined on the inner wall 21 of the reaction vessel 10, it has a size almost in contact with the inner wall of the reaction vessel, so it is a fitting type inner vessel and plays the same role as the lining. Can do. Here, when the portion of the outer wall surface of less than 50% of the inner container has a shape in contact with the inner wall surface of the reaction chamber, the inner container is substantially the capsule-shaped inner container described above. Include. On the other hand, the higher the ratio of contact between the outer wall surface of the inner container and the inner wall surface of the reaction chamber, the closer the inner wall surface of the reaction chamber is to a form lined with silver or a silver alloy. When 50% or more of the outer wall surface of the inner vessel is in contact with the inner wall surface of the reaction chamber, the shape of the outer wall surface of the inner vessel and the shape of the inner wall surface of the reaction chamber are congruent (at this time (Corresponding to 100%), the shape of the outer wall of the inner container and the shape of the inner wall of the reaction chamber are approximated to a certain degree (the shape does not match exactly, reducing the processing costs) , Can have a lining-like function).

  The inner container is made of silver or a silver alloy. The base material made of silver or a silver alloy is preferably a rolled base material, and more preferably a cold-rolled base material. And in order to arrange | position inside the reaction chamber of a reaction container, although processed into the container shape, the junction part is joined by friction stir welding at this time.

  The silver alloy preferably contains 50% by mass or more of silver, and the metal species to be blended with silver is appropriately selected depending on the type of reactant. For example, a silver alloy containing 0.1 to 50% by mass of at least one of Ni, Cu, Zr, Nb, Mo, Ru, Rh, Pd, Ta, W, Re, Os, Ir, Pt, and Au. .

  The inner container manufactured by friction stir welding has bonding strength, and the maximum stress and proof stress are equal to or higher than those of the base material, so there is a low risk of breakage of the bonded portion or leakage of solution from the bonded portion.

  Next, the friction stir welding method will be described. FIG. 1 is a schematic view showing an embodiment of the mechanism of the friction stir welding method. The friction stir welding method includes a step of defining the elongated joining region 2 by bringing the members to be joined 1A and 1B, which are base materials of silver or silver alloy, into contact with each other or substantially contacting each other, and a tool 3 for friction stir welding. Inserting into the joining area 2 while rotating, generating frictional heat between the friction stir welding tool 3 and the joining area 2, generating a plastic area in the heated joining area, and joining members 1 </ b> A, 1 </ b> B to each other Joining. The joined members 1A and 1B are members for forming the inner containers 20 and 30, for example.

  First, the bonded members 1A and 1B, which are silver or silver alloy base materials, are substantially brought into contact with each other on the condition that they are brought into contact with each other or subjected to friction. Further, the joining region 2 is elongated, and continuous joining is performed instead of spot joining. Thereby, the base material of silver or a silver alloy can be friction stir welded. The members 1A and 1B to be joined may be made of the same material or different materials.

  Next, the friction stir welding tool 3 is rotated, and the pin portion 4 is slowly inserted into the coupling region 2. At this time, the shoulder portion 9 is in contact with the surfaces of the members 1A and 1B to be joined. The friction stir welding tool 3 is attached to the motor 7 of the apparatus by a fixing part (not shown) formed in a part of the shank part 5 and is rotated by the motor 7. When the friction stir welding tool 3 rotates while the pin portion 4 is inserted into the coupling region 2, the material at the contact point is rapidly heated by friction, and as a result, the mechanical strength of the material decreases. The friction stir welding tool 3 moves along the advancing direction 8 while kneading and extruding the material. In the coupling region 2, the frictional heat generated by rotating the pin portion 4 and the shoulder portion 9 in contact with each other forms a high-temperature plastic region in the metal around the pin portion 4 and the shoulder portion 9. When the members 1A and 1B are moved in the direction opposite to the movement of the friction stir welding tool 3 or vice versa, the plasticized metal is crushed at the front end of the friction stir welding tool 3 in the advancing direction 8 and mechanically stirred. And it moves to a rear end by the forging action by the shape and rotation direction of the tool 3 for friction stir welding. As a result, the joint portion on the front surface of the friction stir welding tool 3 is heated to create a plastic region. Then, the plastic region is cooled at the rear end of the friction stir welding tool 3 to form a solid weld. All this phenomenon occurs at a temperature lower than the melting point of the members to be joined 1A, 1B.

  In the friction stir welding method, cracks are eliminated, there is no loss of alloy elements due to evaporation of the joint, the alloy components can be held as they are, and a fine granular structure is formed in the joint by press-fitting, stirring and forging action of the welding tool. There is a merit that it is formed.

Examples of the material of the friction stir welding tool 3 include a WC alloy, SKD61, Inconel 600 (registered trademark), Ti-6Al-4V alloy, Ir alloy, Si ₃ N ₄ , Al ₂ O ₃ and the like.

  A comparison was made between friction stir welding and TIG (Tungsten Inert Gas) welding using a member to be joined made of silver. The members to be joined were joined as a pair of 50 mm × 150 mm × 1.5 mmt plate materials made of silver.

Example 1
An Ir alloy tool was used as the friction stir welding tool 3. The joined product was designated as Example 1.

(Example 2)
The joined product obtained in Example 1 was heat-treated in an air atmosphere for 2 hours, and the obtained processed product was designated as Example 2. The heat treatment was controlled so as to be in the range of 500 to 800 ° C.

(Comparative Example 1)
TIG welding was performed to obtain a joined product. The joined product was referred to as Comparative Example 1.

(Comparative Example 2)
The bonded product obtained in Comparative Example 1 was heat-treated in an air atmosphere for 2 hours, and the resulting processed product was referred to as Comparative Example 2. The heat treatment was controlled so as to be in the range of 500 to 800 ° C.

  FIG. 4 shows images of the appearance of the joined product of Example 1 and the joined product of Comparative Example 1. Black impurities that appear to be oxides adhered to the surface of Comparative Example 1.

  FIG. 5 shows an entire cross-sectional image, an enlarged joint image, and an enlarged base material image of the joined article of Example 1. The crystal grain size of the joint is equal to or finer than that of the base material.

  FIG. 6 shows an entire cross-sectional image, an enlarged joint image, and an enlarged base material image of the joined product of Example 2. It can be seen that the crystal grain size of the joint is equal to or finer than that of the base material, and the structure of Example 1 is maintained.

  FIG. 7 shows an entire cross-sectional image, an enlarged joint image, and an enlarged base material image of the joined product of Comparative Example 1. Whereas the base material part is a structure made of equiaxed grains, the structure of the welded part is a structure in which crystal grains grow in the thickness direction of the plate (up and down direction of the image).

  FIG. 8 shows an entire cross-sectional image, an enlarged joint image, and an enlarged base material image of the joined article of Comparative Example 2. It can be seen that the structure of the weld is recrystallized, the grain size becomes coarse, and equiaxed grains.

  About Example 1 and Comparative Example 1, content analysis of C, O, and N was performed by the infrared absorption method. In Example 1, it was C: ± 0 ppm, O: +4 ppm, and N: ± 0 ppm as compared with the base material. In Comparative Example 1, C: +8 ppm, O: +12 ppm, and N: ± 0 ppm. Therefore, it was found that Example 1 contained less gas.

  From the joined articles of Examples 1 and 2 and Comparative Examples 1 and 2, tensile test samples having a width of 7 mm and a length of 35 mm were prepared by wire electric discharge machining, respectively. At this time, the width direction and the joining direction were made to coincide with each other so that the joined portion was positioned at the center of the sample for tensile test. Further, as Reference Example 1, a sample for a tensile test was similarly prepared from a base material having no joint. Further, as Reference Example 2, a sample for a tensile test was similarly produced from a base material that was heat-treated in an air atmosphere for 2 hours. FIG. 9 shows the tensile test result of the sample not subjected to the heat treatment, and FIG. 10 shows the tensile test result of the sample subjected to the heat treatment. Compared to Reference Example 1, Comparative Example 1 was reduced in all of maximum stress, yield strength, and elongation. On the other hand, Example 1 was not deformed because the stirrer structure was hard, and although the overall elongation rate was reduced, both the maximum stress and the proof stress were improved. Moreover, compared with the reference example 2, all of the maximum stress, proof stress, and elongation rate fell in the comparative example 2. On the other hand, in Example 2, since the stirrer structure was hard, it was not deformed, and although the overall elongation rate was reduced, the maximum stress was equivalent to the base material, and the proof stress was improved.

1A, 1B Joined member 2 Joining area 3 Friction stir welding tool 4 Pin part 5 Shank part 6 Back plate 7 Motor 8 Direction of travel of friction stir welding tool 9 Shoulder part 10 Reaction vessel 20 Inner container (capsule)
21 Inner wall of reaction vessel 22 Base 30 Inner vessel (fit type)

Claims (4)

In a method for producing an inner container made of silver or a silver alloy for accommodating a raw material for reaction, which is disposed inside a reaction chamber of a reaction container,
Made of silver or a silver alloy containing 50% by mass or more of silver, using a rolled substrate, the inner container is formed,
A method for producing an inner vessel for a reaction vessel, wherein the joined portion of the inner vessel is joined by friction stir welding. The method for producing an internal container for a reaction container according to claim 1, wherein the internal container has a capsule shape. The inner container has a shape in which 50% or more of the outer wall surface of the inner container is in contact with the inner wall surface of the reaction chamber when arranged in the reaction chamber. Of manufacturing the inner container for the reaction container. The inner container for a reaction container according to any one of claims 1 to 3, wherein a base is disposed between a bottom surface of the reaction chamber of the reaction container and a bottom surface outside the inner container. Manufacturing method.