JPS6238319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a novel ceramic-metal bonded body. In particular, it relates to a strength member on which tensile stress acts on the joint surfaces.

[Prior art]

When ceramics and metal are bonded, because the physical properties of the two, especially the coefficient of thermal expansion, are significantly different, thermal stress is generated during the bonding process or under usage conditions that are subjected to thermal loads, resulting in destruction of the ceramic itself or peeling at the bonded part. Such defects may occur. This tendency occurs particularly as the object to be joined becomes larger. Therefore, especially when bonding ceramics and metal in large structures,
It was extremely difficult.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a ceramic-metal bonded body that avoids the drawbacks of the prior art and can provide a healthy bonded body that does not cause any breakage, especially on the ceramic side.

[Summary of the invention]

In order to avoid the drawbacks of the prior art, the inventors have considered joining ceramics and metal bodies by interposing a Ni--Fe alloy or a metal such as Mo or W, which has a coefficient of thermal expansion approximately between those of the metal body. However, with this joining method, when the ceramics or metals to be joined become large, or when the difference in coefficient of thermal expansion between the two becomes 8×
In cases where the temperature is greater than 10 ^-6 /℃, and in the case of dense ceramics made by hot pressing,
It was discovered that destruction of ceramics due to thermal stress during the bonding process cannot be prevented, leading to the present invention.

The present invention relates to a bonded body of ceramics and metal, characterized in that the ceramics and metal are bonded with a composite of inorganic fibers and metal interposed between the respective bonding members.

That is, in joining ceramics and metal,
Since Mo, W, Ni--Fe alloys, etc. used for relieving thermal stress have high rigidity, the thermal stress relieving material itself deforms uniformly due to temperature differences.

Therefore, even if the coefficient of thermal expansion differs even slightly between the ceramic and the thermal stress relaxation material, the ceramic will break due to the thermal stress. In order to compensate for these shortcomings of thermal stress relieving materials, it is necessary to use metals or alloys with low rigidity for thermal stress relieving materials, so that they have a spring action that helps the thermal stress relieving materials as thermal stress occurs. I confirmed that there is.

A method in which thermal stress relaxation itself has a spring action is possible by including a fibrous inorganic substance that acts as a roller in a single metal or alloy matrix. That is, in order to obtain a thermal stress relieving material having the above-mentioned characteristics, it is possible to include an inorganic substance or metal fiber incompatible with the metal in a metal matrix of a single metal or an alloy.

Combinations of the metal matrix and inorganic or metal fibers with poor wettability include C fibers or B fibers and Cu or Al, and combinations with good wettability include Ni fibers and Cu or Fe. In the former case, it has a spring action due to poor wettability, but in the latter case, it has good wettability, so
Ni fibers and Cu or Fe metals are completely alloyed and rigid, and cannot have spring action.

Therefore, as a composite of an inorganic fiber and a metal matrix that can have a spring action, fibers such as C, B, SiC, Al ₂ O ₃ and Cu,
This can be achieved by a composite with a metal matrix made of one or an alloy of Al, Ni, Mo, Fe, etc. On the other hand, among the composites of inorganic fibers and metal, the composite of C fibers and metal matrix has the greatest spring action. Furthermore, among the C fibers and metal matrix, a composite of C fibers and Cu matrix is most suitable. A composite of C fibers and Cu is obtained by plating C fibers with Cu, forming the fibers into a rope or spiral shape, and hot-pressing the fibers at about 1000°C. As a composite of C fiber and Cu, the C fiber is preferably 30 to 60% by volume, and the coefficient of thermal expansion of this composite at room temperature is 5 to 12×
10 ^-6 /℃. B other than C fibers, SiC, Al ₂ O ₃
Composites of fibers and metals can also be produced in much the same way. In addition, as a composite, the thermal expansion coefficient at room temperature is 3 to 12 × 10 ^-6 /℃ and the elastic modulus is 5 to 13 × 10 ¹³
It was found that a bond with a high strength of Kg/mm ² could be obtained.

[Embodiments of the invention]

Example 1 A 40 mm thick, 40 mm square SiC sintered body doped with 2 wt% BeO was used as the ceramic, and a 40 mm square bar of JIS standard SUS304 stainless steel was used as the metal. A copper-carbon fiber composite was used between the joints. First, ceramics and copper-carbon fiber composite were bonded, and then 40mm
The corner rod is made of JIS standard SUS304 stainless steel and a copper-carbon fiber composite is brazed. The SiC sintered body has a thermal conductivity of 0.6 Cal/cm, sec.℃ at room temperature, and a specific resistance of 10 ¹³
It is Ωcm. BeO containing 0.1 to 3.5% by weight of Be is good.

The copper-carbon fiber composite was manufactured by the following method. Each carbon fiber was subjected to electroless copper plating to a predetermined thickness, and a plurality of the copper-plated carbon fibers were bundled and woven into a predetermined size so that adjacent portions intersected with each other. This fabric was heated under pressure at 800° C. in a nitrogen atmosphere to produce a sheet-like composite with a thickness of 1 mm. In order to obtain a predetermined thickness, by increasing the thickness of the copper-plated carbon fiber bundle, a composite of the desired thickness can be formed with a single woven fabric. Furthermore, a single woven fabric can be made thinner and multi-layered to achieve a desired thickness, and the latter composite is more effective in terms of properties and smoothness. In addition, the present invention is not limited to woven fabrics, and any method can be used, such as a method of forming the fibers into a spiral shape, a method of dispersing short fibers having a length such that the fibers overlap each other, and are arranged.

The Cu-C fiber composite and the SiC sintered body produced as described above were interposed with a brazing material having a thickness of 50 μm consisting of 40% by weight manganese and the balance copper.
℃ and 5 to 10 kg/cm ² of pressure and heat to join. Cu
- 35%, 45% and 54% by volume as C fiber composite
Three types were manufactured including: Furthermore, the complex
30 wt% Cu and 70 between SUS304 stainless steel
They were joined by heating in an Ar atmosphere at 860° C. under a pressure of 5 to 10 kg/cm ² with a 100 μm thick silver solder foil made of %Ag by weight interposed therebetween. The aforementioned Mn is
30-60% by weight is good.

Example 2 Next, a 40 mm square rod of aluminum was used as the metal. A 35% by volume carbon fiber copper composite made of the above-mentioned fabric and having a thickness of 1 mm was used as an intermediate material, and this was preheated to the above-mentioned SiC sintering method using a brazing material consisting of 40% by weight Mn and the balance Cu. joined to the body. After that, the copper-carbon fiber composite was used as a bonding surface.
Placed on a metal body made of aluminum with a 100 μm copper foil interposed, and heated at 580°C for 5 to 50 minutes in an Ar atmosphere.
A pressure of 10 kg/cm ² was applied to bond copper and aluminum using a eutectic reaction. A good bonded body was obtained.

Example 3 An example of a joined body of ceramics and metal in which the present invention is applied to a pipe for a heat exchanger is shown. still,
The ceramic for the heat exchanger was required to be undamaged by various chemical reactions and to have high thermal conductivity equivalent to that of ordinary metals, so the aforementioned SiC ceramic was adopted as the ceramic. JIS standard SUS304 pipe was used as the metal.
The outer diameter of the metal pipe is 100mm, the wall thickness is 10mm, and the length is 500mm.
It is. Therefore, a thermal stress relieving material is required for joining the SiC ceramics and the stainless steel pipe, and in this example, the thermal stress relieving material is 1 mm thick.
A composite of C fiber and Cu was joined between the objects to be joined. In this example, the volume ratio of C fibers in the composite is 35%, the coefficient of thermal expansion is approximately 5 x 10 ^-6 /°C, and the modulus of elasticity is 9 x 10 ³ Kg/.
^mm2 .

First, a foil made of the Cu and 40Wt%Mn alloy was used as a brazing material between the SiC ceramic pipe and the composite, and a regular silver brazing foil was used between the composite and the metal pipe. Used as a material,
Heating to 860℃ and applying pressure of 5 to 10Kg/ ^cm2 ,
iC ceramics and metal pipes were joined in one joining process. The thickness of each brazing filler metal in this example is 50 μm.

As described above, in the Examples, no destruction of the ceramics due to thermal stress during the bonding process was observed, and a healthy bonded body of ceramics and metal was obtained. In this embodiment, the case where SiC sintered body is adopted as the ceramics has been described, but the present invention can also be directly applied to ceramics such as Si ₃ N ₄ and Al ₂ O ₃ .

〔Effect of the invention〕

According to the present invention, in joining ceramics and metal, it is possible to prevent destruction of ceramics due to thermal stress generated during the joining process and during use.
This has the effect that a healthy bond between ceramics and metal can be easily obtained.

Claims (1)

[Scope of Claims] 1. A bonded body of ceramics and metal, characterized in that the ceramics and metal are bonded via a composite of inorganic fibers and a metal matrix. 2. Claim 1, wherein the fiber is C fiber.
A bonded body of ceramics and metal as described in . 3. The ceramic-metal bonded body according to claim 2, wherein the composite is a sintered body of C fibers and Cu. 4 The composite has a C fiber content of 30 to 60% by volume and a thermal expansion coefficient of 4 to 12× at room temperature.
10 ^-6 /°C. The ceramic-metal bonded body according to claim 3.