JPH05169281A - Manufacture of tantalum/copper/stainless steel (carbon steel) clad - Google Patents

Abstract

PURPOSE:To provide the clad method which can strongly join tantalum with stainless steel or carbon steel without depending on the explosive welding. CONSTITUTION:At the combination of tantalum 1, copper 2 and stainless steel, a silver foil 4 is inserted between tantalum and copper, a separation material 5 is laid on these both outer sides, then these total is entered in a bag of stainless mesh 6, the inside of bag is sealed vacuum, heated to 800-1050 deg.C while applying the atmospheric pressure, and tantalum/copper/stainless steel clad is manufactured with diffusion joining.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a tantalum / copper / stainless steel (carbon steel) clad plate having extremely high bonding strength. The tantalum / copper / stainless steel (carbon steel) clad described in the present specification means a tantalum thin plate, a copper thin plate, and a stainless steel thin plate (or a carbon steel thin plate).
And means a clad plate obtained by superposing them in this order.

[0002]

2. Description of the Related Art Tantalum has a very high corrosion resistance and is used in an extremely severe corrosive environment, but on the other hand, its use is limited because it is expensive. To increase demand, it is desirable to use it as a clad because it uses less tantalum and can be used at a lower cost. However, since tantalum is an active metal and is oxidized by heating for hot rolling, it is difficult to manufacture it by hot rolling. Until now, tantalum / copper / carbon steel clad has been manufactured by bombardment. It was However, in the explosive deposition method, if the tantalum is thin, the tantalum is broken by the explosive force, so there is a problem that the thickness of tantalum cannot be made thin, and the cost reduction due to the cladding is difficult to measure.

Since tantalum has a very high melting point of 2995 ° C., and if the base material is only a steel plate, the base material melts during welding of tantalum, so normally, a few mm of copper is sandwiched between the tantalum and the steel plate. By releasing the heat, the steel plate of the base material is prevented from melting. Further, since tantalum easily forms an intermetallic compound with another metal and the intermetallic compound is brittle, it is desirable to sandwich copper which does not form the tantalum and the intermetallic compound between the tantalum and the steel plate as a countermeasure against this.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for firmly joining tantalum and stainless steel or carbon steel as a clad, without using the explosive deposition method.

[0005]

In order to achieve the object of the present invention, tantalum, copper, stainless steel (carbon steel) is used.
Combination of tantalum and copper with silver or Ag
-Insert a thin layer of silver brazing material such as Cu (foil or powder), place release materials on both outsides of these layers, and press 800-
It is a method of manufacturing a clad, characterized by performing diffusion bonding by heating to 1050 ° C.

The inventors examined various methods of joining tantalum and stainless steel or carbon steel as a clad, and a diffusion joining method in which temperature and time are applied in an non-oxidizing atmosphere is one of suitable joining methods. I thought it was. Therefore, when tantalum and carbon steel or stainless steel were directly laminated and heated under vacuum and heated to 1000 to 1100 ° C., they seemed to be joined. However, it peeled off easily with a light impact, so the cross section was taken with a microscope and EPM.
When examined in A, brittle intermetallic compounds were observed. In this way, in an experiment in which tantalum and stainless steel or carbon steel are directly laminated and subjected to temperature and pressure, an intermetallic compound is inevitably formed, and this intermetallic compound is brittle, so it easily peels from the location of the intermetallic compound. I will end up. Therefore,
It has been found that interposing copper that does not form an intermetallic compound is necessary with or without welding, and a diffusion bonding method with a tantalum / copper / stainless copper (or carbon steel) combination is suitable.

When a metal that does not form an intermetallic compound with tantalum was examined, copper was found to be a general practical metal.
It was confirmed that silver and titanium were so. on the other hand,
Fe, Cr, Ni, Co, Al, Sn, Mn, and Au were examined, but all formed tantalum and a brittle intermetallic compound. Therefore, for joining tantalum and steel (carbon steel, stainless steel), it is conceivable to sandwich silver, titanium, etc. between tantalum and steel in addition to copper, but titanium easily forms an intermetallic compound with steel. A two-layer clad of tantalum and titanium may be used, but it is not a good idea to use titanium in the case of a clad with steel. Although sandwiching silver may be a good method, replacing expensive silver with copper having a thickness of 3 mm is costly, which is also not a good idea.

As a diffusion bonding method with a combination that does not form an intermetallic compound, first, a stack of tantalum, copper, and stainless was sequentially heated in vacuum while heating to 1050 ° C., which is close to the melting point of copper. The result is that due to the unevenness of the micron-order plate, the joints are not joined at the recesses,
The bonding strength was low and it was easy to peel off by bending. Silver was used instead of copper, and a stack of tantalum, silver, and stainless steel was similarly heated to 950 ° C., which is close to the melting point (960 ° C.) of silver. However, also in this case, the bonding strength between tantalum and silver was low.

According to the manufacturing method of the present invention, that is, the thickness 1
When a combination of 0 μm silver foil sandwiched between tantalum and copper, or a combination of silver and copper plated with a thickness of 1 to 2 μm and tantalum was tested, it was heated to 960 ° C., which is the melting point of silver. It was found that without heating, silver was reacted with copper and melted by heating to 800 to 850 ° C. to fill the gap between copper and tantalum. Moreover, at 850 ° C. or higher, silver was dissolved in copper and disappeared, and there was no remaining as a low melting point brazing layer. Further, since the thermal conductivity hardly decreases up to 1% of silver only when the impurity in the copper is silver, the role of copper of releasing heat during welding was not impaired. Then, the joining force was significantly improved by the melting of silver. On the other hand, no silver was detected in the tantalum, which did not impair the tantalum performance.

As a method of inserting a thin silver layer, silver foil,
In addition to silver plating, it is also possible to apply powder in terms of shape. Moreover, it is not necessary to use pure silver in terms of composition, and Ag-
The use of Cu alloy is also possible. Since Ag-Cu alloy is supplied in the form of silver brazing strip, powder, or any other shape, these can be used. Prepare a 72% Ag-Cu alloy powder having a eutectic composition of copper and silver as a brazing material,
When the same joining was carried out by sandwiching between copper and tantalum at 800 ° C. slightly higher than the melting point of this, strong joining was also observed.

However, silver brazing fillers are Zn, C depending on the type.
Some include elements such as d, Ni, and Sn that form an intermetallic compound with tantalum. Thus, it should be noted that if the brazing material is improper, it forms an intermetallic compound with tantalum and only a material having low bonding strength can be obtained. Moreover, if impurities from the brazing filler metal remain in the clad material, the brazing component dissolves in the copper, causing a decrease in the copper thermal conductivity due to a decrease in the purity of the copper, impairing the original role of the copper in releasing welding heat. Become.

The inventors have previously proposed a method for producing a diffusion-bonded clad plate using atmospheric pressure as disclosed in Japanese Patent Application Laid-Open No. 3-13283 (Japanese Patent Application No. 1-145093). Tantalum / copper / stainless steel (carbon steel)
It was confirmed that it can be used effectively enough for the clad manufacturing method. This method applies atmospheric pressure, that is, a pressure of 1 Kg / cm ² by filling a bag made of a thin metal plate such as stainless steel with a material to be used as a clad and sealing it in a vacuum. The pressure is not high. However, if used well, it is possible to apply sufficient pressure to the entire bonding interface. In particular,
If a brazing material is used together as in the present invention, it is a very effective joining method.

More specifically, first, the tantalum / copper / stainless steel (carbon steel) clad material and the insert material are stacked, and then the release material is stacked on both sides thereof. Next, after stacking all or more of the same, put the whole in a bag made of oxidation-resistant metal foil such as stainless steel or a thin plate, and apply atmospheric pressure by applying a vacuum to the bag. The method is to heat the entire bag in the air or an inert atmosphere.

When the total thickness of tantalum and copper is small, it is not necessary to insert silver or silver solder between the copper and stainless steel (carbon steel), but when the total thickness of tantalum and copper is large. , Or if the bonding pressure is insufficient, it is necessary to insert silver or silver solder between copper and stainless steel (carbon steel). This is because atmospheric pressure is not transmitted to the entire bonding interface when the plate thickness is thick, and it is thought that a gap is inevitably created. By melting the brazing filler metal, this gap is sufficiently filled to achieve bonding on the entire surface. it is conceivable that.

When the total thickness of tantalum and copper is larger, for example, tantalum is 4 mm and copper is 3 mm.
mm, tantalum, copper and stainless steel (carbon steel)
Even if they are put in a bag at the same time and subjected to atmospheric pressure, the atmospheric pressure does not reach the interface between copper and stainless steel (carbon steel) sufficiently. In such a case, the tantalum / copper / stainless steel (carbon steel) clad can be manufactured by first joining copper and stainless steel (carbon steel) and then joining tantalum again.

The total thickness of tantalum and copper is much larger,
For example, when tantalum is 4 mm and copper is 10 mm, the joint strength can be increased by putting tantalum, copper, and stainless steel (carbon steel) in a bag at the same time and rolling them together. The rolling in this case is not for the purpose of joining at that time, but for the purpose of smoothing the surfaces of the respective materials by rolling so that there is no gap. To do this, the bag does not break when rolled at an extremely slight reduction of about 1% at the temperature just before the melting of silver, and the soft copper at high temperature becomes familiar with tantalum and stainless steel (carbon steel), Since the minute gaps are almost eliminated, the subsequent diffusion bonding by heating allows sufficient bonding. If the rolling reduction exceeds 3%, the conformability becomes worse and the bag ruptures and vacuum leakage occurs, so a reduction of 3% or less, preferably about 1% is desirable.

The thickness of the silver or silver brazing material used is not particularly limited, but it is necessary to change it depending on the total thickness of the clad when manufacturing a particularly thick clad. Also,
The bonding temperature is higher than the Ag-Cu eutectic temperature of 780 ° C. 8
From 00 ℃, lower than the melting point of copper (1083 ℃) 105
Up to 0 ° C is suitable. If the heating rate is too slow, the solid phase may diffuse into the copper before the silver melts, raising the melting point, which may result in incomplete melting at the bonding temperature. I will end up. Therefore, it is necessary to pay attention to the temperature rising speed.

[0018]

EFFECTS OF THE INVENTION According to the present invention, after the inserted silver or silver solder melts and wets the joint surface, the silver diffuses into the copper and is isothermally solidified by increasing the melting point, and tantalum / copper. / A strong bond of stainless steel (carbon steel) cladding is achieved. Furthermore, if a diffusion bonding method using atmospheric pressure is used, the atmospheric pressure acts uniformly on the bonding interface.
It is possible to bond a large area clad with high bonding strength.
Therefore, a clad of tantalum and stainless steel or carbon steel having excellent corrosion resistance can be manufactured at low cost.

[0019]

【Example】

Example 1. As shown in FIG. 1, 1.5 mmt × 600 m
m × 600 mm tantalum plate 1, 2.0 mmt × 600
mm × 600mm copper plate 2, 12mmt × 600mm ×
600 mm SUS316L plate 3, 10 μm x 100
18Cr of 0.3mm thickness in which tantalum / silver foil / copper / 316L layers of silver foil 4 of 6 mm × 600 mm (6 pieces of silver foil are used side by side) are laminated in this order and a temper color is formed on both sides.
-3Al steel 5 is piled up as a release material, and 0.4 mm x 1000 mm x 1000 mm 18Cr is further provided on both outer sides thereof.
Ferritic stainless steel 6 was overlaid. The periphery of this ferritic stainless steel was seam-welded 7 to form a bag, and a pipe 8 was attached to a part of the bag, which was then evacuated. Then, the pipe part was seam welded and vacuum-sealed. During seam welding, a titanium wire having a diameter of 1 mm and a length of about 200 mm was arranged as a getter material side by side with the clad material. In this state, the bag is heated in a furnace at 1000 ° C. for 2 hours, cooled, and then cut around the bag to form 15.5 mm × 6.
A 00 mm x 600 mm tantalum / copper / 316L clad plate was taken out. The shear strength of this clad showed a high value as shown in Table 1. Further, even after welding, the shear strength did not decrease. Further, this clad was capable of forming a mirror plate by cold pressing.

Example 2.2.2 mmt × 1000 mm ×
2000mm tantalum plate, 3.0mmt × 1000m
m × 2000mm copper plate, 12mmt × 1000mm ×
2000mm SUS304 plate, 10μm x 100m
18 × 0.3mmt thick silver foil of m × 2000mm (6 silver foils are used side by side) are stacked in the order of tantalum / silver foil / copper / silver foil / 304, and a temper color is formed on both sides.
Cr-3Al steel is piled up as a release material, and 0.4 mm x 1200 mm x 2400 mm 18C is further provided on both outer sides thereof.
r Ferritic stainless steel was laminated as a bag.
The periphery of the ferritic stainless steel was seam welded, a pipe was attached to a part thereof, and then vacuum drawing was performed. Then, the pipe part was seam welded and vacuum-sealed. During seam welding, the getter material has a diameter of 1 mm and a length of 200 m.
Titanium wires of about m were arranged next to the clad material. In this state, the bag is heated in a furnace at 1000 ° C. for 2 hours, cooled, and then cut around the bag to measure 17.5 mm × 1000 m.
An m × 2000 mm tantalum / copper / 304 clad plate was taken out. Sampled from a portion of this clad,
As a result of measuring the shear strength, a high value was shown as in Table 2.

Example 3. 3.0 mmt × 600 mm × 6
00mm copper plate, 20mmt x 600mm x 600mm
SUS304 plate, 10 μm x 100 mm x 600 m
m silver foil (6 pieces of silver foil are lined up and used) copper / silver foil / 304
In order, and a 0.3 mm thick 18Cr-3Al steel having a temper color formed on both sides thereof is laminated as a release material, and further 0.4 mm × 1000 mm × on both outsides thereof.
1000 mm 18Cr ferritic stainless steel was laminated as a bag. The periphery of this bag was seam-welded, and a pipe was attached to a part of the bag, which was then evacuated. Then, the pipe part was seam welded and vacuum-sealed. During seam welding, the getter material has a diameter of 1 mm and a length of 200.
Titanium wires of about mm were arranged side by side on the clad material. In this state, heat in a furnace at 1000 ° C. for 2 hours, cool, and then cut the periphery of the bag to obtain 23.0 mm × 600 mm
A 600 mm copper / 304 clad plate was taken out. This clad and thickness 4.0mmt × 600mm × 600m
m tantalum plate and 10 μm x 100 mm x 600 mm silver foil (6 silver foils are used side by side) tantalum / silver foil / copper 3
04 clad in this order, and a 0.3 mm-thick 18Cr-3Al steel with a temper color formed on both sides of the clad is stacked as a release material, and 0.4 mm × 10 on both outer sides.
00 mm x 1000 mm 18Cr ferritic stainless steel was laminated. The periphery of this ferritic stainless steel was seam-welded to form a bag, and a pipe was attached to a part of the bag, which was then evacuated. Then, the pipe part was seam welded and vacuum-sealed. During seam welding, a titanium wire having a diameter of 1 mm and a length of about 200 mm was arranged as a getter material side by side with the clad material. 10 in this state
After heating in a furnace at 00 ° C. for 2 hours and cooling, the periphery of the bag was cut, and a 27.0 mm × 600 mm × 600 mm tantalum / copper / 304 clad plate was taken out. As a result of sampling from a part and measuring the shear strength, a high value was shown as in Table 3.

Example 4.4.0 mmt × 400 mm × 4
00 mm tantalum plate, 10.0 mmt x 400 mm x
400mm copper plate, 15mmt x 400mm x 400m
m SUS304 plate, 10 μm × 100 mm × 400
18mm-3mm of 0.3mmt thick silver foil (4 silver foils are used side by side) stacked in the order of tantalum / silver foil / copper / silver foil / 304 and tempered on both sides.
Overlaid with steel as a release material, and 0.4m on both outsides
A m × 1000 mm × 1000 mm 18Cr ferritic stainless steel was laminated as a bag. The periphery of the ferritic stainless steel was seam welded, a pipe was attached to a part thereof, and then vacuum drawing was performed. Then, the pipe part was seam welded and vacuum-sealed. During seam welding, a titanium wire having a diameter of 1 mm and a length of about 200 mm was arranged as a getter material side by side with the clad material. In this state, heating was performed in a furnace at 750 ° C. for 2 hours, and hot rolling was performed as it was, aiming at a reduction rate of about 1%. The bag was then returned to the heating furnace as it was, heated at 1000 ° C. for 2 hours, cooled, and then cut around the bag to take out a tantalum / copper / 304 clad plate of about 28.0 mm × 400 mm × 400 mm. As a result of sampling from a part and measuring the shear strength, a high value was shown as in Table 4.

[0023]

[Table 1] Interfacial shear strength (Kg / mm ² ) Ta / Cu 20.3 Cu / stainless steel 19.8

[0024]

Table 2 Interface Shear strength (Kg / mm ² ) Ta / Cu 18.0 Cu / Stainless steel 18.2

[0025]

[Table 3] Interface shear strength (Kg / mm ² ) Ta / Cu 17.4 Cu / stainless steel 20.5

[0026]

[Table 4] Interface Shear strength (Kg / mm ² ) Ta / Cu 19.3 Cu / Stainless steel 21.2

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a first embodiment.

[Explanation of symbols]

 1 Tantalum plate 2 Copper plate 3 SUS316L plate 4 Silver foil 5 Release material 6 Ferritic stainless steel 7 Seam welding 8 Pipe

Claims (5)

[Claims] 1. Tantalum, copper, stainless steel (carbon steel)
Combination of tantalum and copper, silver or A
Insert a thin layer of silver brazing material (foil or powder) such as g-Cu, place release materials on both outsides of these layers, and pressurize at 800
Tantalum / copper / stainless steel (carbon steel) characterized by diffusion bonding by heating to 1050 ° C
Clad manufacturing method. 2. Tantalum, copper, stainless steel (carbon steel)
In this combination, a thin layer of silver brazing material (foil or powder) such as Ag or Ag-Cu is inserted between tantalum and copper, and copper and stainless steel, and a release material is placed on both outer sides of these layers, and then the A method for producing a tantalum / copper / stainless steel (carbon steel) clad, which comprises performing diffusion bonding by heating to 800 to 1050 ° C. while pressing. 3. Tantalum, copper, stainless steel (carbon steel)
In the combination of the above, by applying silver plating or Ag-Cu alloy plating to all or any of the materials, only the interface between tantalum and copper, or the interface between tantalum and copper, and copper and stainless steel (carbon steel) At the interface of
It is characterized in that a thin silver brazing layer such as silver or Ag—Cu is present, a release material is placed on both outer sides of these layers, and then heated to 800 to 1050 ° C. while being pressurized to perform diffusion bonding. A method for producing a tantalum / copper / stainless steel (carbon steel) clad. 4. The method according to any one of claims 1 to 3, wherein the whole is put in a bag of metal foil such as stainless steel or a thin metal plate together with release materials on both outer sides for pressurization, and the inside of the bag is vacuum-sealed. A method for producing a clad which heats while applying atmospheric pressure. 5. The method of claim 4, wherein the bag is 600 per bag.
After performing extremely light rolling of 3% or less at a hot temperature of up to 950 ° C to improve the familiarity between the materials, 800 to 105
A method for manufacturing a clad which is heated to 0 ° C.