JPH07155983A - Brazing method using active metal brazing and active metal brazing material - Google Patents

Abstract

(57) [Abstract] [Purpose] When brazing with an active metal braze containing an active metal such as titanium in a vacuum furnace with a vacuum degree of about 1 to 10 ^-2 Pa, the surface of the brazing material is oxidized and defects occur. To prevent the occurrence of. [Structure] The material 11 to be joined is made of low alloy steel, and the joining material 12 is made of tungsten-copper alloy. The active metal solder 13 is an Ag-Cu eutectic solder in which Ti is dispersed. A protective layer 14 is plated on the surface of the active metal solder 13. These are combined together and installed in a vacuum furnace (not shown) which is maintained at about 1 to 10 ^-2 Pa, heated to a predetermined temperature and brazed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method and an active metal brazing material using an active metal brazing material containing an active metal such as titanium in a vacuum furnace having a vacuum degree of about 1 to 10 ^-2 Pa.

[0002]

2. Description of the Related Art An active metal brazing material containing an active metal such as titanium shows good wettability even to a ceramic material which cannot be wetted by a conventional brazing material for vacuum brazing. Also, for tungsten steel materials etc., the wettability is better than that of conventional vacuum brazing brazing filler metals due to the reduction effect of oxides on the surface of brazing filler metals by active metals, and the bonding strength is high. Become.

Since the active metal brazing material contains an active metal such as titanium, it is more likely to be oxidized than the conventional brazing material. For this reason, vacuum brazing using active metal brazing is usually 10 ^-3 Pa.
It is performed in a high vacuum.

When the active metal solder is melted in the brazing filler metal, it becomes brittle, and it becomes difficult to process it into a thin sheet. For this reason, a thin structure such as a sandwich structure in which a sheet of active metal is sandwiched between conventional brazing filler metals for vacuum brazing, or a structure in which active metals are finely dispersed in a conventional brazing filler metal for vacuum brazing is used. It is easy to process into a sheet.

[0005]

In a small vacuum furnace, a high vacuum can be easily obtained by using a metal material for both the heating element and the heat insulating material. However, in large-scale furnaces that are actually used for production, carbon heaters and ceramic fibers or carbon insulation materials are often used because of cost and durability. Further, a vacuum degree of about 1 to 10 ^-2 Pa is often used. In this case, especially when the temperature is raised, the surface of the active metal braze is often oxidized due to a large amount of degassing from the voids of the ceramic fiber or the pores of the carbon. When the surface of the active metal brazing material is oxidized, it becomes difficult to melt and the wettability is deteriorated, and brazing defects are likely to occur.

In the brazing material having the sandwich structure described in the prior art, the active metal is not exposed on the surface, so that it is difficult to oxidize under the above conditions, but there is a problem that the active metal is difficult to disperse during brazing. is there.

The object of the present invention is to braze with an active metal braze containing an active metal such as titanium in a vacuum furnace having a vacuum degree of about 1 to 10 ^-2 Pa. It is an object of the present invention to provide a brazing method and an active metal brazing material using an active metal brazing material which is prevented from being generated.

[0008]

SUMMARY OF THE INVENTION The present invention is 1-10 ^-2 Pa
When brazing with an active metal braze containing an active metal such as titanium in a vacuum furnace with a degree of vacuum, brazing is performed with a brazing filler metal having a protective layer containing no active metal on the surface of the brazing filler metal. It was done like this.

[0009]

Function When the temperature is raised during the brazing heat cycle, a large amount of gas is released from the gap of the heat insulating material in the vacuum furnace. At this temperature rise, the brazing material is not yet melted and its surface is covered with a layer made of an inactive element, so that it is difficult to oxidize. It takes about 60 minutes to reach the brazing temperature, but during this time, the degassing from the gap of the heat insulating material decreases. Therefore, when the brazing temperature is reached and the brazing material is melted, even when the active metal is exposed to the atmosphere in the vacuum furnace, it is not oxidized as in the case of heating. Therefore, the melted brazing material is sufficiently wet in the brazing portion to be brazed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a setup state in one embodiment of the present invention. The material to be welded 11 is φ50 × 100 low alloy steel, the material to be welded 12 is φ
It is a 50 x 30 tungsten-copper alloy. Activated metal wax 13
Is an Ag-Cu eutectic braze in which 2 wt% of Ti is dispersed. The dimensions are φ50 × 0.1. Activated metal wax 13
A protective layer 14 is plated on the surface of the. The protective layer 14 is formed by copper plating with a thickness of several μm. An active metal brazing material 13 having a protective layer 14 is sandwiched between the materials 11 and 12 to be bonded,
It is installed in the vacuum furnace 21 shown in.

Next, the inside of the vacuum furnace 21 is maintained at a vacuum degree of about 1 to 10 ^-2 Pa, and the carbon heater 22 is used to heat the material to be bonded 11, the bonding material 12 and the brazing material 15. Since the carbon heater 22 is generating heat, the gas contained in the carbon pores exits the pores in a short time and is discharged to the outside of the vacuum furnace. On the other hand, although the gas is also contained between the fibers of the alumina fibrous heat insulating material 23, the heat insulating material 23 does not generate heat and is only heated. I can't cut it. The degassing from the heat insulating material 23 easily oxidizes the active metal braze, but in this embodiment, the surface of the active metal braze 13 is covered with the protection 14 as shown in FIG.

The melting point of the active metal braze 13 is about 790 ° C.
It takes about 60 minutes to reach this temperature. Insulation material during this
Outgassing from 23 is reduced. When the melting point of the brazing material reaches 790 ° C. or higher, the active metal brazing material 13 melts. Since the protective layer 14 is pure copper and has a melting point of 1083 ° C., the protective layer alone does not melt. However, the protective layer 14 is eroded by the molten active metal braze 13. Since the protective layer 14 is several μm thick, it is entirely eroded and alloyed in the active metal braze 13. Since the thickness of the protective layer 14 is sufficiently thin as compared with the active metal braze 13,
Even if alloyed, the melting point of the brazing material does not change significantly.

Even if the active metal brazing material 13 is exposed to the atmosphere in the vacuum furnace at this stage, the degassing from the heat insulating material 23 is reduced, so that it is not oxidized. When kept at 800 to 850 ° C. for 10 to 20 minutes, the active metal brazing material wets the materials 11 and 12 to be bonded well. Then, the brazing is completed by cooling in the vacuum furnace.

According to this embodiment, the active metal brazing material is covered with the protective layer and is not oxidized when the temperature rises because the heat insulating material is largely degassed and the active metal brazing material is easily oxidized. Also,
During brazing, the protective layer is alloyed in the active metal braze, so that the protective layer remains and does not adversely affect brazing. Therefore, good brazing is possible even when brazing is performed using an active metal braze in a vacuum furnace having a vacuum degree of about 1 to 10 ^-2 Pa with degassing from the heat insulating material.

As the active metal brazing material, Ag-Cu-In-Ti system having a lower melting point or Cu-Ti is used.
A system, or an active metal other than Ti such as Zr and Hf may be used. In addition to plating, the protective layer may be formed by PVD such as vapor deposition, sputtering, and ion plating. In this case, a thin and dense protective layer can be formed. When the brazing material is rolled, the protective layer may be formed by sandwiching an active metal brazing material with a protective material and rolling the brazing material.

The material of the protective layer is not limited to copper, but silver, N
i or ordinary brazing material Ag-Cu, Ag-Cu
A brazing material such as -In may be used. The present invention may be carried out as follows instead of the above method.

Graphite and copper are used as a joining material, and an Ag-Cu-Ti type brazing material is used as an active metal brazing material. Since the degassing also occurs inside the graphite pores of the bonding material, the active metal braze is easily oxidized. By coating the surface of this active metal brazing material with Ag—Cu eutectic brazing material, it is possible to prevent the brazing material from being oxidized when the temperature rises with a large amount of degassing. Similar effects can be expected in brazing of other material combinations such as graphite-graphite, ceramics-metal, ceramics-ceramics.

[0018]

As described above, according to the present invention, 1
When brazing with an active metal braze containing an active metal such as titanium in a vacuum furnace with a vacuum degree of about 10 ^-2 Pa, a protective layer that is difficult to oxidize is provided on the surface of the active metal braze. It is possible to prevent the brazing material from being oxidized and causing defects.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing a setup state of materials to be joined and the like according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a state of installation in a vacuum furnace according to an embodiment of the present invention.

[Explanation of symbols]

11 ... Joined material, 12 ... Joining material, 13 ... Active metal brazing material, 14 ... Protective layer, 15 ... Brazing material, 21 ... Vacuum furnace, 22
… Carbon heater, 23… Insulation, 24… Stand

Claims (2)

[Claims] 1. When brazing using an active metal braze containing an active metal such as titanium in a vacuum furnace having a vacuum degree of about 1 to 10 ^-2 Pa, a gas component remaining in the vacuum furnace is used. A brazing method using an active metal, wherein brazing is performed using a brazing material having a protective layer containing no active metal on the surface of an active metal brazing material which is easy to react. 2. A vacuum degree of about 1 to 10 ^-2 Pa, which is characterized in that a protective layer containing no active metal is provided on the surface of an active metal braze which easily reacts with a gas component remaining in a vacuum furnace. Active metal brazing material used in the vacuum furnace.