KR101058849B1 - Hot Isotropic Pressure Diffusion Bonding Method Using Release Agent - Google Patents

Abstract

The present invention relates to a hot isotropic pressure diffusion bonding method using a release agent, in the hot isotropic pressure diffusion bonding method for bonding an object, preparing a bonding object, the release agent is installed on the inner surface of the can in contact with the object And a canning step of charging the object in the can and sealing the can, a vacuum sealing step of converting the inside of the can into a vacuum state, a hipping step of putting the can into a pressurized heating furnace, and the can; It characterized in that it comprises a decanning step of separating the object. The present invention configured as described above can easily separate the can and the object, there is no loss of material and there is an advantage that can solve the problems caused by dust.

Diffusion Bonding, Hot Isotropic Pressing, HIP, Release Agent, Boron Nitride (BN), Molybdenum (Mo)

Description

Hot Isotropic Pressure Diffusion Bonding Method Using Release Agents {Method of HIP Diffusion Bonding Using Release Material}

The present invention relates to a hot isotropic pressure diffusion bonding method using a release agent, and more particularly to a hot isotropic pressure diffusion bonding method using a release agent for easily separating the can and the object.

Metallurgical joining of the metal materials separated from each other includes a welding method of melting and welding the base metal of the object to be joined, and injecting a third molten material between the two base materials and mediating the third material. Soldering (Soldering and Brazing) method for joining the two base materials, and the diffusion bonding (bonding bonding) in which the two base materials are brought into close contact with each other and the mutual diffusion between the atoms constituting the two objects to be bonded.

Among the above metal joining methods, diffusion bonding is a bonding method widely used in the industry in recent years. In order to avoid the disadvantages of the metal joining method by welding or soldering, a semiconductor manufacturing equipment which requires very precise and high reliability, It is widely applied in the field of precision scientific experiment devices such as fusion device and particle accelerator.

Diffusion bonding method is a method of joining in the solid state state by applying heat and pressure in the elastic deformation region and diffusion of atoms generated in the bonding surface. It is called pressure diffusion bonding because it is made by compressing the joint to maintain high pressure on the joint surface. In this case, atoms of each material penetrate by diffusion into the other material, and the two materials are integrally bonded in this process. Becomes

In the case of the metal material, since the diffusion of atoms occurs very actively at a temperature of 40 to 70% of the melting point in terms of absolute temperature, the bonding is well performed by controlling the temperature together with the pressure during the pressure diffusion bonding.

Diffusion bonding (HIP, Hot Isostatic Processing, hereinafter referred to as "HIP") is a method of diffusion bonding (hereinafter referred to as `` hot isostatic pressure diffusion bonding ''). Charged into a metal can (called a canning process), the inside of the can is kept in a vacuum state, and an inert gas such as argon is injected into the can, and charged into a chamber of high pressure and high temperature of 1,000 kgf / cm 2 or more. It is a joining method.

In such a hot isostatic pressing process, when the can is pressed by external pressure, pressure is applied to the material to be bonded in all directions, so that the diffusion of atoms constituting the material from the surface to be bonded occurs to bond the two separated materials.

However, in this diffusion bonding method, diffusion bonding does not occur only between the materials to be bonded, but diffusion bonding occurs between the can and the surface of the material, so that the can is bonded to the outer surface of the bonded product.

Therefore, after joining the material by HIP, the can bonded to the surface should be removed. This is called 'decanning'.

Until now, the decanning process removes the bonded can material on the surface of the product by machining, and in the case of expensive materials such as gold, there is a loss of material, and beryllium, which is used in blankets of a fusion reactor, etc. Due to chips and dust generated during cutting process, the human body has high risks such as impaired beryllium in the respiratory system, which impairs the safety of workers. In the case of materials with complex external shape, it is difficult to machine (cut) have.

The present invention for solving the problems described above is an object to easily separate the can and the object during the decanning in the hot isotropic pressure diffusion bonding method.

In addition, the purpose of the present invention is to solve the problem of risk factors due to material loss or dust in the decanning process through machining.

The present invention for achieving the above object in the hot isotropic pressure diffusion bonding method for bonding the object, preparing a bonding object, the step of installing a release agent on the inner surface of the can in contact with the object, the A canning step of charging the object inside and sealing the can, a vacuum sealing step of converting the inside of the can into a vacuum state, a heaping step of putting the can into a pressurized heating furnace, and a dividing of the can from the object. Characterized in that it comprises a canning step.

In addition, the release agent is characterized in that any one of boron nitride or molybdenum.

In addition, the release agent is provided in a sheet shape, characterized in that installed between the can and the object.

In addition, the canning step, characterized in that the charging of a plurality of objects to be bonded, and to install the release agent between the object and the object.

In addition, the canning step, characterized in that to charge a separate filling member into the empty space after charging the object.

In addition, the vacuum sealing step is characterized in that it further comprises the step of sealing the vacuum exhaust is provided in the can after converting the interior of the can into a vacuum state.

In addition, the vacuum sealing step, characterized in that to maintain the internal pressure in a vacuum atmosphere of 1,000 kgf / ㎠ or more.

In addition, the releasing agent installation step, characterized in that installed after the releasing agent is attached to any one of the inner surface or the object of the can.

The present invention constructed and functioned as described above has the advantage that decanning is very easy because the material of the can is not bonded to the surface of the product because it uses a release agent.

Therefore, there is no need for machining, such as easy to work, there is no loss of material, there is no harm to the human body does not have the problem of dust or chips scattered during decanning if the material is harmful to the human body.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the hot isotropic pressure diffusion bonding method using a release agent according to the present invention will be described in detail.

1 is a flow chart in a hot isotropic pressure diffusion bonding method using a release agent according to the invention, Figure 2 is a cross-sectional view of the can is applied to the release agent in a hot isotropic pressure diffusion bonding method using a release agent according to an embodiment of the present invention, Figure 3 is a cross-sectional view of a can to which a release agent is applied in a hot isotropic pressure diffusion bonding method using a release agent according to another embodiment of the present invention, and FIG. 4 is a combination table of materials capable of diffusion bonding.

Hot isotropic pressure diffusion bonding method using a release agent according to the invention, the step of preparing a bonding object (S100), the step of installing a release agent between the object to be bonded to the inner surface of the can (S200), and the The canning step (S300) of charging the object inside and sealing the can, the vacuum sealing step (S400) of converting the inside of the can into a vacuum state, and the hips of putting the can into a pressurized heating furnace (HIPping) step (S500) and the decanning step (S600) for separating the object bonded to the can is characterized in that it comprises a.

Object preparation step (S100) is to prepare a separate material to be bonded to the object 300 to be bonded, while processing the appearance of the two materials in the design shape, but the surface to be bonded is precisely polished to improve the bonding efficiency.

In addition, a can (Can; 100), which is a container for sealing the object 300, is prepared in a size and a shape in which the materials can be loaded, and the can is a vacuum exhaust 120 capable of removing air therein. Is provided on one side.

Release agent installation step (S200) is, as shown in Figure 2, to prevent the contact between the can and the object during the HIP by installing the release agent 200 between the object to be bonded to the inner surface of the can 100.

The method of installing the release material (Release Material; 200) may be proposed in various ways, but by processing the release agent into a thin film (sheet), the bottom and wall of the inside of the can and the surface facing the inside of the cover 110 of the can. It is most preferable to set it as the method of attaching a mold release agent, and it can also charge in a can after attaching a mold release agent to an object preferentially. That is, the release agent is installed on all surfaces of the object and the can in contact with each other.

Figure 2 is to produce a single object (product) in the can, showing that the release agent is installed only between the product and the inner surface of the can, and when looking at Figure 3 when a plurality of objects with one can 100 at the same time It shows how to install the release agent.

In order to join a plurality of objects in one can, both the release agent 200 must be installed on a surface where the object and the can contact each other, and a surface where the object and the object contact each other.

 In addition, when fabricating objects having different dimensions into one can, instead of manufacturing the can into a complicated shape, the can is manufactured in a simple form, and a separate filling member 310 is charged into the remaining empty space, thereby providing a plurality of objects. So that you can join at once. At this time, a release agent is inserted between the object and the filling member 310.

The release agent is a material that does not occur diffusion bonding with both the can material and the material of the bonding target material to prevent the can and the object from being bonded after hot isotropic pressure.

4 illustrates a combination capable of diffusion bonding, and a release agent may be selected with reference to this table. For example, if the can is made of stainless steel and the materials to be joined are beryllium and copper alloy, respectively, stainless steel, beryllium, and copper alloy do not have diffusion bonding. You can use zero.

Meanwhile, in the hot isotropic pressure diffusion bonding method, as the release agent that can be used in the majority of the can and the material of the object, boron nitride (boron nitride; BN) and molybdenum (Mo) sheets may be mainly used.

Boron nitride is a new ceramic material called white graphite. Nitrogen and boron are combined in a hexagonal structure similar to graphite. Chemical and physical properties are similar to graphite, but unlike graphite, they are used as electrical insulation materials. . Boron nitride can be molded by atmospheric pressure sintering or HIP method, and can be processed into various shapes such as metal processing by ordinary machine tools.

Boron nitride is stable and sublimates at this temperature up to a high temperature of 3,000 ° C. In addition, in the atmosphere in which oxygen is present, oxidation occurs rapidly at about 600 ° C., and the thermal expansion coefficient of 0.07 × 10 ⁻⁶ / ° C. can neglect the change in shape with temperature, and thus all kinds of metal materials thereof in a vacuum atmosphere. It can be used as a release agent for diffusion bonding by HIP.

Molybdenum is a metal with a very high melting point along with tungsten, and the diffusion of atoms does not occur at a temperature where atoms of other metal materials diffuse well. In addition, at high temperatures, the vapor pressure is low, so that the gas is not discharged during the diffusion bonding under high temperature and high pressure, but rather, it is combined with the surrounding oxygen to absorb the oxygen flowing out of the material to improve the bonding performance. Therefore, molybdenum can be used as a release agent in diffusion bonding between various kinds of metals.

The molybdenum sheet which can be used as a releasing agent is in the form of a foil, and it is generally preferable to use one having a thickness of 0.03 to 0.2 mm.

The canning step S300 is a step of sealing the cover 110 of the can after charging the processed materials into the prepared can 110. Before the cover is sealed by welding or the like, the release agent 200 is installed on the upper surface of the object 300 as described above. The canning step (S300) is finished by inserting an object into the can and then closing the material charging hole with the cover 110, and then welding the sealing around the cover.

The vacuum sealing step (Pinch Closing; S400) is a step of sealing by removing air in the can 100 and maintaining it in a vacuum state.

If the air inside the can is not completely removed, air remains in the gap formed by the surface irregularities of the object joint 400 to act as an air cushion, which prevents contact between the joints in the pressurizing step and prevents diffusion bonding from occurring at the site. Alternatively, air diffuses into the material and significantly lowers the bond strength.

Therefore, vacuum sealing is performed, and a vacuum pump (not shown), which is an external device, is connected to the vacuum exhaust 120 provided in the can 100, and a vacuum pump is operated to vacuum the inside of the can, and then the vacuum exhaust. The can is sealed by welding the furnace or mechanically pressing the air outlet to seal it.

Next, the hipping step (HIPping; S500) is loaded into the vacuum-sealed cans in the pressurized heating furnace (not shown) after the object is charged, injecting a high-pressure gas into the pressurized heating furnace and the internal temperature of the pressurized heating furnace to a high temperature It is a step to maintain. At this time, the gas used is an inert gas such as argon as in the conventional HIP, and the internal pressure of the pressurized furnace is maintained at 1,000 kgf / cm2 or more, and the pressure depends on the material of the material to be joined by the HIP method. Set the appropriate pressure for each. For example, in the case of joining steel, it is known that the internal pressure of the pressure furnace is 1,500 kgf / cm 2.

In addition, the internal temperature of the pressurized heating furnace in the heating step (S500) is maintained at the temperature at which the atomic diffusion of the material is most active, and is usually 40-70% of the melting point (absolute temperature).

In addition, while the pressing step is performed, the can is pressed by the external high pressure, the pressure diffusion welding is performed by pressing from the front of the object charged into the can. The pressurized heating furnace used for the HIP is to maintain a high pressure of 1,000 kgf / ㎠ or more in the internal pressure as described above in one embodiment is to promote safety by the method of buried underground.

The decanning step (S600) is a step of removing the can fixed to the outside from the object after cooling and taking out after cooling while lowering the temperature of the pressurized heating furnace to room temperature after the heaping step.

The release agent 200 corresponding to the main technical gist of the present invention is installed between the can 100 and the object 300 so that the material of the can is separated by the surface and the release agent of the object in the hipping step, so that the decanning is very easy. For example, when decanning, a portion of the can is cut and then the can is removed.

The present invention configured as described above can easily separate the can and the object (material) without additional machining during decanning, and there is no loss of material because machining is unnecessary, and can stably even when the material is harmful to human body. There is an advantage that can be separated from the object.

While the invention has been described and illustrated in connection with a preferred embodiment for illustrating the principles of the invention, the invention is not limited to the construction and operation as shown and described.

Rather, those skilled in the art will appreciate that many modifications and variations of the present invention are possible without departing from the spirit and scope of the appended claims. And all such modifications and changes as fall within the scope of the present invention are therefore to be regarded as being within the scope of the present invention.

1 is a flow chart in a hot isotropic pressure diffusion bonding method using a release agent according to the present invention,

Figure 2 is a cross-sectional view of the can is applied to the release agent in the hot isotropic pressure diffusion bonding method using a release agent in one embodiment according to the present invention,

3 is a cross-sectional view of the can is applied to the release agent in a hot isotropic pressure diffusion bonding method using a release agent in another embodiment according to the present invention,

4 is a combination table of materials capable of diffusion bonding.

<Description of the symbols for the main parts of the drawings>

100: can

110: cover

200: release agent

300 material

310: filling member

400: junction

500: exhaust passage

Claims (8)

In the hot isotropic pressure diffusion bonding method for joining the object, Preparing a bonding object; Installing a release agent on the inner surface of the can in contact with the object: A canning step of inserting the object into the can and sealing the can; A vacuum sealing step of converting the inside of the can into a vacuum state; A hiping step of putting the can into a pressurized heating furnace and hiping; And And a decanning step of separating the can and the object. The release agent is a hot isotropic pressure diffusion bonding method using a release agent, characterized in that provided in a sheet shape and installed between the can and the object. The method of claim 1, wherein the release agent, Hot isotropic pressure diffusion bonding method using a release agent, characterized in that any one of boron nitride or molybdenum. delete The method of claim 1, wherein the canning step, A hot isotropic pressure diffusion bonding method using a release agent, wherein a plurality of objects to be bonded are charged and the release agent is installed between the objects and the object . The method of claim 4, wherein the canning step, Hot isotropic pressure diffusion bonding method using a releasing agent, characterized in that after filling the object to charge a separate filling member into the empty space. The method of claim 1, wherein the vacuum sealing step, And converting the interior of the can into a vacuum state and then sealing the vacuum exhaust gas provided in the can. According to claim 1 or 6, wherein the vacuum sealing step, Hot isotropic pressure diffusion bonding method using a release agent characterized in that the internal pressure is maintained in a vacuum atmosphere of 1,000 kgf / ㎠ or more. According to claim 1, The release agent installation step, Hot release isotropic pressure diffusion bonding method using a release agent, characterized in that the release agent is attached to any one of the inner surface of the can or the object.

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