JP2009137770A - Method of manufacturing fired body used for hot isotropic pressure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a fired body, in which a fired body easy in machining and free from the occurrence of damage or the deterioration of heat insulation effect if used at ≥1,200°C can be obtained in the manufacture of a support for supporting heating device of a hot isotropic pressure device and a heat insulation structure. <P>SOLUTION: The method of manufacturing the fired body used for the hot isotropic pressure device includes a molding step S1 of forming a mold 26 by impregnating woven fiber or unwoven fiber comprising a ceramic fiber, a first firing step S2 of firing a primary fired product 27 having 1.5-2.5 g/cm<SP>3</SP>density by firing the mold 26 at <1,200°C, a machining step S3 for machining the primary fired product and a second firing step S4 of obtaining a secondary fired product 28 as the fired body by firing the primary fired product after machining at ≥1,200°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a fired body used in a hot isostatic pressing apparatus.

  The hot isostatic pressing method (hot isostatic pressing method, HIP method) is a method in which a metal or ceramic material is fired at a high density in a high-pressure gas atmosphere or is diffusion-bonded. It is widely used for density sintering or diffusion bonding, or for removing defects such as gas pores and nests in castings. A hot isostatic pressurization apparatus (hereinafter referred to as an HIP apparatus) used for carrying out the HIP method includes a high-pressure vessel capable of enclosing high-pressure gas. The high-pressure vessel is disposed so as to surround the object to be processed and is disposed so as to surround the heating device that heats the object to be processed, the support that holds the heating device, and the heating device and the support. And a heat insulating structure.

By the way, in a conventional HIP apparatus, a molybdenum alloy or the like having excellent heat resistance has been used for the support body that supports the heating apparatus and the inner wall material of the heat insulating structure. However, the molybdenum alloy is expensive in material price and may be nitrided when nitrogen is used as the high-pressure gas. Therefore, as in Patent Document 1, an HIP device in which a support and an inner wall material are formed of a sintered body of an inorganic material has been developed.
In patent document 1, the baking body of a support body and a heat insulation structure is manufactured with the following method. First, for the fired body of the support, a woven fabric formed of ceramic fibers mainly composed of alumina is rolled up into a cylindrical shape and then formed into an oxide-based sol or oxide fine powder slurry (alumina or A mold is formed by impregnating a silica-based sol). Then, the mold is fired, and the fired product is manufactured by performing mechanical processing such as drilling and window formation on the fired product.

In addition, the fired product of the heat insulation structure is fired in the same manner as the support fired body, and the fired product is subjected to mechanical processing such as drilling to attach the fired body to the fixing member at the bottom of the heat insulation structure. The sintered body is manufactured. A heating device and a high-pressure vessel are attached to the thus obtained support and the fired body of the heat insulating structure, and these are assembled as a HIP device.
JP 2007-78293 A

By the way, the fired body used in Patent Document 1 is composed of a composite inorganic material of ceramic fibers mainly composed of alumina and metal oxide fine particles. When this composite inorganic material is fired at a firing temperature of 1200 ° C. or higher, the firing progresses, the hardness increases, and the machinability significantly decreases. Therefore, in the HIP apparatus of Patent Document 1, it is very difficult to perform machining after firing, and problems such as a long machining time have occurred.
On the other hand, when the firing temperature of the composite inorganic material is lowered to less than 1200 ° C., machining after firing becomes easy. However, HIP devices are often used at 1200 ° C. or higher.

Therefore, for example, when a support that has been fired at less than 1200 ° C. is incorporated into the HIP device, firing proceeds at an actual use of 1200 ° C. or more, and the dimensional difference between the support and the heater element increases, resulting in a HIP device. Cause damage.
As for the inner wall material, for example, if the one fired at less than 1200 ° C. is used for the heat insulating structure, the inner wall material shrinks due to firing at an actual use of 1200 ° C. or higher, and there is a gap between the inner wall material and the heat insulating material. It is possible to reduce the heat insulation performance and cause a decrease in the heat insulation effect of the HIP device.
The present invention has been made in view of the above-mentioned problems, and can be easily machined. However, even when actually used at 1200 ° C. or higher, the support is not damaged and the heat insulation effect is not lowered. It aims at providing the manufacturing method of the sintered body used for a hot isostatic pressurization apparatus.

In order to achieve the object, the method for producing a fired body used in the hot isostatic pressing apparatus of the present invention employs the following technical means.
That is, a heating device that is disposed so as to surround the object to be processed and that heats the object to be processed, a support that supports the heating device, and a heat insulating structure that is disposed in a mantle shape with respect to the heating device and the support A hot isostatic pressing apparatus comprising a body in a high-pressure vessel, the method for producing a fired body used when the support and the inner wall material of the heat insulating structure are formed from a fired body, The body is produced according to the following steps (1) to (4).

(1) A step of impregnating a woven fabric or non-woven fabric made of ceramic fibers with a metal oxide binder to form a mold (2) The mold is fired at a temperature of less than 1200 ° C. to obtain a density of 1.5-2. A step of firing a primary fired product of 5 g / cm ³ (3) A step of machining the primary fired product (4) A step of firing the post-machined primary fired product at 1200 ° C. or higher. Step of obtaining a secondary fired product and obtaining the secondary fired product as the fired body In this way, since primary firing is performed at less than 1200 ° C., firing proceeds in the primary firing and the hardness of the material is large. There is no increase. Therefore, when machining is performed after the primary firing, machining can be easily performed using a general tool made of high-speed steel or cemented carbide.

And since the fired body after machining is secondarily fired at 1200 ° C. or higher and then assembled as a hot isostatic pressing device, firing proceeds even after actual use at temperatures exceeding 1200 ° C. There is no. Therefore, even when actually used, the dimensional difference between the support and the heater element does not increase, and there is no possibility that the support is deformed or damaged. In addition, the inner wall material does not shrink due to actual use, and there is no gap between the inner wall material and the heat insulating material.
That is, according to the production method of the present invention, a fired body that can be easily machined but does not cause damage to the support or decrease in the heat insulating effect even when actually used at 1200 ° C. or higher is obtained. Can do.

Further, when the size of the mold is reduced by δ% in the step (2) and / or (4), the mold is formed to have a size larger than the secondary fired product by a contraction of δ%. Good.
In this way, since the mold is formed with dimensions that allow for shrinkage in the primary firing and the secondary firing, the support and the inner wall material can be finished to the predetermined dimensions after the secondary firing. A hot isostatic pressing device can be easily assembled using the support and the inner wall material after the next firing as they are.

Furthermore, when the size of the primary fired product shrinks by ρ% in the step (4), the machining may be performed with a size larger than the shrinkage of ρ% with respect to the secondary fired product.
In this way, since machining is performed with dimensions taking into account the shrinkage in the secondary firing, the support and the inner wall material can be finished to the predetermined dimensions after the secondary firing, and the support after the secondary firing. In addition, the hot isostatic pressing device can be easily assembled using the inner wall material as it is.

  According to the method for producing a fired body used in the hot isostatic pressing apparatus of the present invention, the support can be damaged or thermally insulated even if it is actually used at 1200 ° C. or higher, although it can be easily machined. It is possible to obtain a fired body in which the decrease in the temperature does not occur.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front sectional view of a hot isostatic pressing device according to the present invention. A hot isostatic pressurizing apparatus 1 (hereinafter referred to as an HIP apparatus 1) has a cylindrical high-pressure vessel 2 having a processing chamber 9 in which high-pressure gas can be accommodated. In the processing chamber 9, a heating device 3 that is disposed so as to surround the workpiece W and heats the workpiece W, a support 4 that supports the heating device 3, and the heating device 3 and the support 4 are provided. On the other hand, a heat insulating structure 5 arranged in a jacket shape is provided. The HIP device 1 heats the high-pressure gas in the processing chamber 9 by the heating device 3, thereby enabling hot isostatic pressing (HIP processing) of the workpiece W.

In the following description, the top and bottom of the page of FIG. 1 are the top and bottom when the HIP device 1 is described.
As shown in FIG. 1, the high-pressure container 2 includes a cylindrical container body 6, an upper lid part 7 that covers the upper surface of the container body 6, and a lower lid part 8 that covers the lower surface of the container body 6. . A cylindrical processing chamber 9 is formed inside the container body 6.
The upper lid portion 7 is provided with an inlet / outlet port 10 that communicates the inside and outside of the container body 6. Via the inlet / outlet port 10, high-pressure gas is supplied into the container body 6 (inside the processing chamber 9) or the container body The high-pressure gas in 6 (inside the processing chamber 9) can be discharged to the outside. A stage 11 is formed on the lower lid portion 8 so as to project upward toward the processing chamber 9 (inside the container body 6), and a workpiece W can be placed on the stage 11. . The upper lid portion 7 and the lower lid portion 8 are supported by a window frame-shaped press frame (not shown) so that the internal pressure of the high-pressure gas can be supported even when the high-pressure gas is sealed in the processing chamber 9.

2 and 3 show the heating device 3 and the support 4 accommodated in the processing chamber 9 of the high-pressure vessel 2.
The heating device 3 includes a heater element 12 disposed so as to surround the object to be processed W. The heater element 12 is composed of a plurality of electric heating resistance wires 13 (three wires in this embodiment) in the vertical direction. Each electric heating resistance wire 13 meanders while the middle side of the wire is alternately bent up and down, and this meandering portion is disposed so as to surround the outer peripheral surface of the support 4. Lead portions 14 drawn out to the lower end side of the support 4 are provided at both ends of each of the electric resistance wires 13, and the electric resistance wires 13 can be energized via the lead portions 14.

Each electrothermal resistance wire 13 is made of a metal material such as a platinum alloy or a molybdenum alloy, and can heat a high-pressure gas to about 1600 ° C. Further, a thermocouple (not shown) for temperature measurement is provided in the vicinity of each electrothermal resistance wire 13 so that the temperature of the high-pressure gas can be adjusted with high accuracy.
The support 4 is formed in a cylindrical shape that is long in the vertical direction (cylindrical in the present embodiment), and a plurality of windows 15 that communicate with the inside and outside of the cylinder are formed on the side surface in the circumferential direction. A plurality of these window portions 15 are provided in the vertical direction (three in this embodiment), and the heater elements 12 of the heating device 3 are attached so as to correspond to these window portions 15. These window portions 15 are formed as openings that communicate between the inside and outside of the support 4, and are formed so as to ensure the circulation of the high-pressure gas heated by the heater element 12 and promote convection. Yes. By providing the window 15 on the support 4, the heating efficiency of the HIP device 1 is improved, and the control accuracy and responsiveness when controlling the temperature of each heater element 12 can be increased.

As shown in FIG. 1, the heat insulating structure 5 includes an inner wall member 16 disposed on the inner peripheral side, inner and outer two-layer heat insulating members 17a and 17b provided on the outer peripheral side of the inner wall member 16, and two inner and outer layers. The outer wall member 18a provided between the heat insulators 17a and 17b and the outer wall member 18b covering the outer heat insulator 17b. The inner wall member 16, the heat insulators 17a and 17b, and the outer wall members 18a and 18b are all formed in a shape (inverted cup shape) in which a bottomed cylinder is turned upside down, and are nested with each other. .
The inner and outer two-layer heat insulators 17a and 17b are formed of a heat insulating material such as ceramic fiber or zirconia felt to a thickness of about 2 to 20 mm. By forming the heat insulators 17a and 17b with ceramic fibers and zirconia felt to a thickness of 2 to 20 mm, the heat retaining property of the processing chamber 9 can be improved.

The outer wall materials 18a and 18b are formed using a metal material such as stainless steel, for example. The inner wall material 16 is integrally formed with a vertically long cylindrical body 19 and a lid plate 20 formed so as to close an opening above the cylindrical body 19, and the inner wall material 16 is heat-insulated in machining described later. A hole for attaching to the fixing member 21 at the lower part of the body is provided.
The support body 4 of the HIP device 1 and the inner wall material 16 of the heat insulation structure 5 described above are formed of a fired body. In the present embodiment, the fired body is manufactured according to the following manufacturing method.
As shown in FIG. 4, the fired body is manufactured in the order of a molding step S1, a primary firing step S2, a machining step S3, a secondary firing step S4, and an assembly step S5.

In the molding step S1, an inorganic material composed of a substrate made of ceramic fibers and a metal oxide binder is molded into the shape of the support 4 to form the mold 26. The molding step S1 of the present embodiment is performed by winding the base body into a cylindrical shape in accordance with the shape of the support body 4, and then impregnating with a metal oxide binder. The mold 26 formed in the molding step S1 is sent to the primary firing step S2.
The substrate is a woven or non-woven fabric of ceramic fibers whose main component is alumina, and is formed by combining ceramic fibers having a diameter of about 2 to 5 μm in a mesh form or randomly. The metal oxide binder is a sol or slurry in which fine particles of alumina or silica are suspended, and fine particles having a particle size of 200 mesh or less are used so that the substrate can be densified by filling the spaces between the ceramic fibers. Yes.

The primary firing step S2 is performed by firing the molding die 26 at a firing temperature of less than 1200 ° C. to form a primary fired product 27 having a density of 1.5 to 2.5 g / cm ³ . The conditions (temperature and time) of the primary firing step S2 vary depending on the shape and composition of the mold 26 to be fired and the firing temperature, but those skilled in the art can determine the conditions based on operating conditions and past results. Is possible. For example, in the case where the mold 26 composed of an alumina ceramic fiber base and an alumina binder is subjected to the primary firing step S2 at 1000 ° C., the firing time is 2 to 12 hours. The primary fired product 27 is sent to the machining step S3.

The reason why the firing temperature in the primary firing step S2 is less than 1200 ° C. is to obtain the primary fired product 27 having a good machinability and a density of 1.5 to 2.5 g / cm ³ . To the density of the primary sintered product 27 and 1.5 g / cm ³ or more, when impregnated with binder such as alumina substrate density 0.9~1.0g / cm ^3, the density after sintering is necessarily This is because it becomes 1.5 g / cm ³ or more. The reason why the density of the primary fired product 27 is 2.5 g / cm ³ or less is to ensure the machinability of the primary fired product 27 by a gold saw or a drill.
The machining step S <b> 3 performs drilling or cutting on the primary fired product 27. In the machining step S3 of the support 4, the window portion 15 is formed on the primary fired product 27 using a high-speed steel or cemented carbide gold saw or the like, or the heater element 12 using a bit tool. A mounting hole or the like for mounting is formed. The primary fired product 27 for which the machining step S3 has been completed is sent to the secondary firing step S4.

In the secondary firing step S4, the primary fired product 27 after the machining step S3 is secondarily fired at a firing temperature of 1200 ° C. or higher to obtain a secondary fired product 28 having a density of 2.2 to 3.0 g / cm ^3. To form. The firing temperature of the secondary firing step S4 is preferably 1200 to 1600 ° C., and deformation / breakage of the support 4 and the heater element 12 can be suppressed or prevented by performing the secondary firing step S4 at a firing temperature in this range. It becomes like this. In other words, if secondary firing is performed at a temperature selected according to the actual use temperature (temperature of HIP treatment) from the range of 1200 to 1600 ° C, it is supported even if the HIP treatment is repeatedly performed at an actual use temperature of 1200 ° C or higher. The dimensional difference between the body 4 and the heater element 12 is not increased, and the support body 4 is suppressed or prevented from contracting from the heater element 12 and causing deformation or breakage. The secondary fired product 28 is sent to the assembly step S5 as the final fired body, that is, the support body 4.

In the assembling step S5, the heating device 3 is attached to the support 4, and then the heat insulating structure 5 is disposed around them, and these are further disposed in the high-pressure vessel 2, and the HIP device 1 is assembled.
The manufacturing method described above is a method for manufacturing a fired body used for the support 4, but the method for manufacturing the fired body used for the inner wall material 16 is also performed in the same manner.
That is, the fired body of the inner wall material 16 is also manufactured in the order of the molding step S1, the primary firing step S2, the machining step S3, the secondary firing step S4, and the assembly step S5. However, in the case of the inner wall material 16, the cylindrical body 19 and the cover plate 20 are formed as an integral cup shape in the molding step S <b> 1. An example of the inorganic material configuration of the joint portion between the cylindrical body 19 and the cover plate 20 is shown in FIG. As shown in FIG. 5, the inner wall member 19 is configured by overlapping a plurality of cylinders 19 and a cover plate 20 (three in this embodiment). The edge of the lid plate 20 is bent substantially at a right angle, and the bent edge is joined so as to overlap the side surface of the cylindrical body 19. By making both into an integral cup shape with the configuration shown in FIG. 5, the airtightness of the cup-shaped inner wall material necessary for the HIP device can be ensured. And after machining the hole for attaching the inner wall material 16 to the fixing member 21 at the lower part of the heat insulating structure in the machining step S3 after the primary firing step S2, the primary fired product 27 whose machining has been completed is secondary. It is sent to the firing step S4. The fired body subjected to the secondary firing is sent to the assembly step S5 as the inner wall material 16.

Next, the dimensional change (volume change) that occurs in the primary firing step S2 and the secondary firing step S4 described above will be described.
The primary firing step S2 vaporizes and removes moisture and the like contained in the sol or slurry used in the molding step S1, and at the same time, obtains strength sufficient to withstand machining in the subsequent machining step S3. It is a process. Since the firing temperature in the primary firing step S2 is less than 1200 ° C., the dimensional change in this step S2 is a slight value. Therefore, although it is preferable to consider the dimensional change in this step for strict dimensional control, the dimensional change in the primary firing step S2 is taken into consideration in the general dimensional control of the sintered body. Often not necessary.

Next, the dimensional change (volume change) that occurs in the secondary firing step S4 will be described. FIG. 6 is a diagram showing the relationship between the firing temperature and the dimensional change when the primary fired product that has undergone the primary firing process S2 is fired in the secondary firing process S4.
As shown in FIG. 6, when the firing temperature is less than 1200 ° C. (for example, point P in FIG. 6), dimensional elongation due to thermal expansion is observed. However, when the firing temperature exceeds 1200 ° C. (for example, Q point in FIG. 6), the sintering proceeds and the primary fired product tends to become smaller (shrink) due to firing. After the secondary firing, the process proceeds to the cooling process. In the cooling process, however, the dimensions are reduced by the dimension that has been extended by thermal expansion. At this time, even after the cooling is finished, the sintering proceeds and the size is reduced, so that the size after the secondary firing is smaller than that before the secondary firing (for example, point R in FIG. 6).

When the above-described dimensional change due to the secondary firing is applied to this embodiment, the secondary firing step is performed at a firing temperature of 1400 ° C. in this embodiment. When dimensional shrinkage occurs at the firing temperature of 1400 ° C., the primary fired product having a size of 100% before the secondary firing becomes a size of (100−ρ)% after the secondary firing.
Here, consider the dimensions of the mold 26 for forming the secondary fired product 28 as designed. If the dimensional change of the molding die 26 due to the primary firing is X%, the secondary firing product 28 undergoes a dimensional change of X + ρ% (= δ%) with respect to the molding die 26. Therefore, it is preferable that the size of the mold 26 is increased by δ% with respect to the design size of the secondary fired product 28. In this way, even if the dimensions of the inorganic material change due to the shrinkage in the primary firing step S2 and the secondary firing step S4, the support 4 and the inner wall material 16 are finished to the predetermined dimensions after the secondary firing. The secondary fired product 28 can be incorporated into the HIP apparatus as it is. However, since the dimensional change X% due to the primary firing is small as described above, there is no practical problem even if the size of the mold 26 is increased by ρ% which is the shrinkage in the secondary firing step S4.

Further, when the dimensions of the primary fired product 27 and the dimensions of the secondary fired product 28 are compared, the size of the secondary fired product 28 is smaller by ρ% than the primary fired product 27 as shown in FIG. Shrink). Therefore, it is preferable to process the dimension (process dimension) of the machining step S3 by ρ% larger than that of the secondary fired product 28. If it does in this way, the window part 15 and insertion hole which are formed by machining process S3 can be finished to a predetermined dimension after secondary baking process S4, and the secondary baked product 28 is integrated in the HIP apparatus 1 as it is. Can do.
By using a fired body made of a ceramic fiber base and a metal oxide binder for the support 4 and the inner wall material 16, brittleness is improved and thermal stress generated by mechanical impact and temperature distribution is hardly broken. . In other words, the rapid growth of cracks that occur when the ceramic fibers that make up the substrate are subjected to thermal stress, etc., and the cracks do not run instantaneously like normal ceramics, resulting in failure. It becomes difficult to break.

The inorganic material preferably contains 98% or more of alumina in order to improve heat resistance (high temperature strength). In particular, when combined with a platinum alloy or molybdenum alloy heater element 12, the operating temperature of the HIP device 1 may exceed 1400 ° C. However, if the support 4 is formed of a fired body mainly composed of alumina, the heat resistance temperature of the support 4 becomes 1600 ° C. or higher. Even if the heater element 12 made of platinum alloy or molybdenum alloy is used, the heater element 12 Can withstand heating.
The present invention is not limited to the above-described embodiments, and the shape, structure, material, combination, and the like of each member can be appropriately changed without changing the essence of the invention.

In the above embodiment, the molding step S1 is performed by winding the base body into a cylindrical shape in accordance with the shape of the support body 4, and then impregnating the binder with a metal oxide. However, after the base is impregnated with a binder of metal oxide, it can be wound into a cylindrical shape in accordance with the shape of the support 4.
In the said embodiment, while forming the window part 15 as machining process S3 with respect to the primary baked goods 27 of the support body 4, it inserts as machining process S3 with respect to the primary baked goods 27 of the inner wall material 16 of the heat insulation structure 5. FIG. The hole drilling was illustrated. However, cutting, bending, deburring, etc. can be performed as the machining step S3.

  In the above embodiment, the fired body is used for the support 4 and the heat insulating structure 5. However, the fired body can also be used for members other than these in the HIP apparatus 1, such as a insulator for holding the heater element 12, an object mounting base, and the like.

It is front sectional drawing of the hot isostatic pressurization apparatus which concerns on this invention. It is a front view of the heating apparatus of a hot isostatic pressurization apparatus. It is the sectional view on the AA line of FIG. It is process drawing which shows the manufacturing method of the sintered body of this invention. It is a figure which shows the junction part of the cylinder and cover plate in an inner wall material. It is a figure which shows the relationship between the calcination temperature of an inorganic material, and the amount of thermal changes of a dimension.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot isostatic-pressure pressurization device 2 High pressure vessel 3 Heating device 4 Support body 5 Thermal insulation structure 6 Container main body 7 Upper lid part 8 Lower lid part 9 Processing chamber 10 Injection discharge port 11 Stage 12 Heater element 13 Electrothermal resistance wire 14 Lead Part 15 Window part 16 Inner wall material 17 Heat insulator 18 Outer wall material 19 Cylindrical body 20 Cover plate 21 Fixing member 26 Mold 27 Primary fired product 28 Secondary fired product S1 Molding step S2 Primary firing step S3 Machining step S4 Secondary Firing process S5 Assembly process W Object to be processed

Claims (3)

A heating device that is disposed so as to surround the object to be processed and that heats the object to be processed, a support that supports the heating device, and a heat insulating structure that is disposed in a jacket shape with respect to the heating device and the support. Is a method for producing a fired body used when forming the support and the inner wall material of the heat insulating structure with a fired body.
A method for producing a fired body used in a hot isostatic pressing apparatus, wherein the fired body is produced according to the following steps (1) to (4).
(1) A step of impregnating a woven fabric or non-woven fabric made of ceramic fibers with a metal oxide binder to form a mold (2) The mold is fired at a temperature of less than 1200 ° C. to obtain a density of 1.5-2. A step of firing a primary fired product of 5 g / cm ³ (3) A step of machining the primary fired product (4) A step of firing the post-machined primary fired product at 1200 ° C. or higher. A step of obtaining a secondary fired product and obtaining the secondary fired product as the fired body   When the size of the mold is reduced by δ% in the step (2) and / or (4), the mold is formed to have a size larger than the secondary fired product by a contraction of δ%. The manufacturing method of the sintered body used for the hot isostatic pressurization apparatus of Claim 1 characterized by the above-mentioned.   The size of the primary fired product is reduced by ρ% in the step (4), and the machining is performed with a size larger than the secondary fired product by a shrinkage of ρ%. A method for producing a fired body used in the hot isostatic pressing apparatus according to 1 or 2.

Images