JPH0723268B2 - Ceramics-Metal bonding material - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a joining member of ceramics and metal.

[Technical background of the invention and its problems]

Various ceramics such as silicon nitride, silicon carbide, and alumina have been widely used as structural members and various functional members by taking advantage of their unique properties.
In many cases, the ceramic itself is used alone. If a metal can be bonded to such ceramics, it is considered that the obtained member can be used in a wider field as a member having a new function.

In the above-mentioned ceramic-metal joint member, when it is a structural component, the joint strength between the ceramic and the metal is required to be sufficiently high, while when it is a functional member, there is continuity at the joint interface between the ceramic and the metal. Required to have. However, in general, ceramics and metals are materials having different atomic bond states, and their chemical properties such as reactivity; thermal expansion coefficient; electrical conductivity and other physical properties are different from each other. At times, it is difficult to form a metallurgical bonding state at the bonding interface.

By the way, conventionally, the following various methods have been known as a method for metallurgically joining ceramics and metal.

Apply a mixture of powder containing Mo-Ti-W as the main component and an organic binder to the surface of the ceramic to be joined to the metal,
In a humid atmosphere, heat to 1400-1700 ° C to react,
A method in which a layer called metallizing is formed, then Ni plating is applied to the metallizing layer, and then a metal (for example, Cu base material) is bonded to the Ni plating by Pb-Sn solder or the like.

A method of joining ceramics and a metal by using an alloy whose main component is a noble metal such as Au and Pt, that is, a metal having a small affinity for oxygen.

A method in which an active metal such as Ti or NbZr or an active metal hydride that is converted into an active metal by heat treatment is interposed at the joint between ceramics and metal, and then the two are joined at high temperature and high pressure.

However, the above method has a drawback that it requires many steps and is complicated. Although the above method can be joined in a simple process, since an expensive precious metal is used, the economical merit is extremely small, and high pressure is required so that the ceramic and the metal come into sufficient contact with each other. Although the above method enables strong bonding due to the action of the active metal, it requires high bonding pressure as in the above method, and therefore is not preferably applied to parts or the like that are not susceptible to deformation.

In order to solve such problems, US Patent No. 2,857,
No. 663 discloses the following joining method. In this method, an active metal is interposed in the joint between the transition metal and the ceramic, the joint is heated to a temperature higher than the melting point of the alloy of the transition metal and the active metal and lower than the melting point of the transition metal, This is a method in which atoms are diffused into each other to form an alloy, and a transition metal and a ceramic are joined by this alloy.

However, the above method has a problem that cracks frequently occur in the ceramic during the process of cooling the obtained ceramic-metal joint member. This is a phenomenon based on the thermal stress generated between ceramics and metal. For example, if the ceramic is alumina, silicon nitride, linear thermal expansion coefficient of each is ^{8.8 × 10 -6 /℃,2.5×10 -6 / ℃} , its value than Cu, Ni, etc. Fe is about 1 It is a few orders of magnitude smaller, and the thermal stress generated at the joint between the two becomes larger. Moreover, the thermal stress increases as the difference between the temperature during joining and the temperature during cooling (room temperature) increases. Therefore, in order to reduce the thermal stress, it is required to lower the temperature at the time of joining,
This requires the use of a low melting point brazing material at the time of joining.

In order to solve the above-mentioned problems, Japanese Patent Application Laid-Open No. 56-163093 proposes a joining method and develops a joining member constituted by diffusing a brazing material containing an active metal into both ceramics and metal. However, these methods have problems in terms of productivity and the like because complicated steps and long-time heat treatment are unavoidable, and are not always effective in relaxing thermal stress between ceramics and metal.

As a method for achieving stress relaxation when the above method is applied, a soft metal layer is interposed between ceramics and metal, and thermal stress is relaxed by its plastic deformation and elastic deformation (Japanese Patent Laid-Open No. 56-41879). ), A method of interposing a layer of a material having a coefficient of linear expansion between ceramics and metal (Japanese Patent Laid-Open No. 55-113678), and the coefficient of linear expansion changes from small to large from ceramics to metals. A method of sequentially laminating a plurality of layers and interposing them (Japanese Patent Laid-Open No. 557544)
Etc. are disclosed.

However, in the case of the above-described joining method using a brazing filler metal containing an active metal, the molten brazing filler metal often protrudes from the joint due to the pressure applied to the joint surface. If the amount of the molten brazing filler metal that has overflowed increases, cracks may occur in the ceramics due to thermal stress due to the difference in thermal expansion coefficient between the ceramics and the brazing filler metal during the process of solidifying and cooling. In order to prevent this phenomenon, it is necessary to determine the optimum amount (thickness) of the brazing filler metal that has no protrusion and is necessary for the brazing filler metal to wet the entire joint area. It is very difficult to determine the optimum amount of brazing filler metal depending on conditions such as temperature and atmosphere. Further, a method of mechanically preventing the protrusion is possible, for example, a method of sealing the outer circumference of the joint with a material having poor wettability with the brazing material, but this method makes it difficult to select a material having poor wettability. Not only that, but it also complicates the joining process, which is difficult to call a realistic method.

[Object of the Invention]

The present invention is intended to provide a ceramic-metal bonding member that has high bonding strength at high temperatures and that prevents cracking of ceramics due to thermal effects.

[Outline of Invention]

The present inventors have conducted intensive studies on a joining member in which a stress-absorbing member is interposed between ceramics and a metal and are wholly joined with a brazing material, and as a result, use of a particle dispersion strengthened composite layer as the stress-absorbing member. As described above, a ceramic-metal joining member having a high joining strength at high temperature as described above and preventing generation of cracks in the ceramic due to thermal influence was found.

That is, the ceramic-metal bonding member according to the present invention is bonded to the bonding surface of the ceramic and the metal with the particle dispersion strengthening type composite layer interposed, and the composite layer has a porosity of 1 to 1.
It is characterized in that the particle dispersion rate in the matrix metal is 2 to 12% by volume at 30% by volume.

Examples of the ceramics include oxide ceramics such as Al ₂ O ₃ and ZrO ₂ , carbide ceramics such as SiC and TiC, and nitride ceramics such as Si ₃ N ₄ and AlN.

Examples of the metal include Fe, Ni, Co, Ti, Mo, W, Nb, Ta, Zr.
Or these alloys etc. can be mentioned.

The particle dispersion strengthened composite layer can be obtained by a powder metallurgy method or an internal oxidation method. Examples of the matrix metal of the composite layer include Al, Cu, Ni, Fe, Co, Ti and Zr. As the dispersed particles, for example, ZrO ₂ ,
CeO ₂ , TiO ₂ , SiO ₂ , ThO ₂ , Al ₂ O _{3 and the} like can be mentioned, and the grain size is preferably 10 μm or less, and the smaller, the more effective.

At this time, when the distance between the particles is reduced, the yield strength is increased, and the mechanical strength is improved especially at high temperatures.

The reason why the particle dispersion rate of the particle dispersion strengthened composite layer is limited is as follows. When the particle dispersion rate is less than 2% by volume, the shear strength at high temperature is lowered. On the other hand, if the particle dispersion ratio exceeds 12% by volume, the composite layer itself becomes too hard and the stress relaxation effect becomes insufficient.

The reason why the porosity of the particle dispersion strengthened composite layer is limited is as follows. The porosity is 1% by volume
If it is less than the above range, the stress relaxation effect cannot be sufficiently exhibited. On the other hand, when the porosity exceeds 30% by volume, the shear strength is lowered. A more preferable porosity is 1 to 10% by volume.

The above particle dispersion strengthened composite layer (including those having pores)
The thickness of is preferably 0.3 mm or more. The reason for this is that if the thickness of the composite layer is less than 0.3 mm, it becomes difficult to effectively absorb the thermal stress generated between the ceramic and the metal, and the strength of the joint is significantly reduced, or Cracks may occur.

In such a particle dispersion-reinforced composite layer, the following effects largely contribute to the absorption of thermal stress.

(A) Innumerable fine pores dispersed in the particle dispersion strengthened composite layer composed of Ni, Fe, Co or their alloys, which may have a hardness of matrix metal of Hv80 or more, cause thermal stress. Absorb. That is, the thermal strain caused by the difference in thermal expansion between the ceramics and the metal is absorbed by the holes.

(B) Soft matrix metal, such as hardness Hv80 or less
Thermal stress is absorbed by plastic deformation or elastic deformation of Cu, Al, etc. or their alloys.

When the porosity of the above (a) is large, the strength of the particle dispersion-reinforced composite layer decreases, so the particle dispersion amount is increased for the purpose of preventing the strength decrease, while when the porosity is small, the particle dispersion amount is The porosity and the amount of dispersed particles are selected so as to reduce the thermal stress most and to improve the strength by reducing the amount.

Example of Invention

 Examples of the present invention will be described below.

Example 1 First, a silicon nitride cylinder having a diameter of 13 mm and a thickness of 5 mm, a diameter of 13 m
A disk of structural carbon steel (JIS, S45C) having a thickness of 5 mm and a thickness of 5 mm was prepared. Also, a particle dispersion strengthened composite plate of Ni-3 wt% Al ₂ O _{3 having} a diameter of 15 mm and a thickness of 0.8 mm (density 92 to 93%, particle size of Al ₂ O ₃ 0.0
5 μm) was prepared.

Then, the composite plate is interposed between the silicon nitride cylinder and the carbon steel disc, and a Ti foil and Cu having a thickness of 3 μm are respectively provided between the silicon nitride cylinder and the composite plate and between the composite plate and the carbon steel disc.
After sandwiching the foils and stacking them, hold them under the conditions of 5 × 10 ^-5 Torr and 950 ° C × 4 minutes while applying a pressure of 10 kg / cm ² , and subsequently cool them in argon gas to bond silicon nitride-carbon steel. The member was obtained.

Shear stress was applied to the joint surface of the obtained joint member, and the shear strength from room temperature to 600 ° C. was measured. In addition, as Comparative Example 1, the thickness was used instead of the particle dispersion-reinforced composite plate.
A silicon nitride-carbon steel joint member was produced under the same conditions as in Example 1, except that a 0.8 mm pure Ni plate was used, and the shear strength was similarly measured. The results are shown in the figure. In addition, A and B in the figure show the characteristic lines of the joining members of the present Example 1 and Comparative Example 1, respectively.

As is clear from the figure, the joining members in Example 1 each have a shear strength of 11 kg / s from room temperature to 600 ° C.
It is presumed that the thermal stress of silicon nitride and carbon steel is sufficiently relaxed because it is at least mm ² . On the other hand, in the case of Comparative Example 1, a shear strength of 1 to ² kg / mm ² was recognized at room temperature to 200 ° C., but cracks had already occurred in the silicon nitride of the joining member, and in the pure Ni plate It can be seen that the thermal stress is not relaxed sufficiently. The measurement itself could not be performed at 300 ° C or higher.

Example 2 Between the same silicon nitride cylinder and carbon steel disc as in Example 1, Cu-3 having a diameter and a diameter of 15 mm shown in Table 1 below having different thicknesses and densities was used.
Weight% Al ₂ O ₃ particle dispersion strengthened composite plate (Al ₂ O ₃ particle size 0.05
10 μm thick Ag foil between the silicon nitride columnar body and the composite plate and between the composite plate and the carbon steel disc.
After sandwiching the Ti foil with a thickness of μm and stacking them, hold them under the conditions of 5 × 10 ⁻⁵ Torr, 850 ° C. × 6 minutes while applying a pressure of 1 kg / cm ² .
Subsequently, it was cooled in argon gas to obtain 6 kinds of silicon nitride-carbon steel joint members.

Then, with respect to the joint members of Examples 2 to 7, shear stress was applied to the joint surfaces at 600 ° C., and the high temperature shear strength was measured. The results are also shown in Table 1 above. In Table 1, high temperature shearing of four kinds of silicon nitride-carbon steel joint members obtained by the same method as in Example 2 using oxygen-free copper plates having different thicknesses instead of the particle dispersion strengthened composite plate. Comparative strength 2 to strength
It was also written as 5.

As is clear from Table 1 above, the shear strength of the joining member of this example is 0.2 when the thickness of the particle dispersion-reinforced composite plate is 0.1 mm.
It is extremely low at kg / mm ^2, and thermal stress is hardly relaxed. When the thickness of the composite plate becomes 0.3 mm, the relaxation of thermal stress progresses and a strength of about 3.6 kg / mm ² is obtained. When the thickness is further increased to 0.8 mm, the shear strength reaches about 85 kg / mm ² . However, even if the thickness is 0.8 mm, when the density of the composite plate becomes low (Example 7; density 78.8%), the shear strength becomes low. However, this value is about 5.9 kg / mm ² , which is higher than that of the comparative example. The maximum shear strength in Comparative Examples 2 to 5 is about 3.
It is 7 kg / mm ² , and only about 44% of the examples can be obtained.

Example 8 First, a square silicon nitride plate having a size shown in Table 2 below and a thickness of 2 mm, and a square carbon steel plate having a size shown in Table 2 and a thickness of 10 mm were prepared. A particle dispersion strengthened composite plate of Ni-3 wt% Al ₂ O ₃ (density 92 to 93%, Al ₂ O ₃ particle size 0.05 μm) having the same dimensions as the silicon nitride plate and a thickness of 1.0 mm was prepared.

Then, the composite plate is interposed between each of the silicon nitride plates and each of the carbon steel plates according to the dimensions of the respective silicon nitride plates,
After sandwiching Ti foil and Cu foil with a thickness of 3 μm between the silicon nitride plate and the composite plate and between the composite plate and the carbon steel plate,
By treating under the same conditions as in Example 1, ten kinds of silicon nitride-carbon steel joining members were obtained.

The appearance (presence or absence of cracking of silicon nitride) of the obtained joint member was observed. The results are also shown in Table 2 above.
In Table 2, the appearance observation results of the silicon nitride-carbon steel joint member obtained by the same method as in Example 8 were used except that pure Ni plates having the same dimensions as the composite plates were used instead of the composite plates. It was also described as Comparative Example 6.

As is clear from the above Table 2, in the present embodiment 8 bonding surface of the silicon nitride plates no cracks occur until ^□ 80 mm, is observed a high thermal stress relaxation effect of particle dispersion strengthened composite plate. On the other hand, in the case of Comparative Example 6, cracks did not occur when the bonding surface of the silicon nitride plate was only ^□ 10 mm, but cracks occurred when the area was larger than that, and the thermal stress relaxation effect of the pure Ni plate was not sufficient. I understand.

Example 9 First, a square silicon nitride plate having a size shown in Table 3 below and a thickness of 2 mm, and a square carbon steel plate having a size shown in Table 3 and a thickness of 10 mm were prepared. Particle-dispersion-strengthened composite plates of Cu-3 wt% Al ₂ O ₃ (density 99.0%, Al ₂ O ₃ particle size 0.05 μm) each having the same dimensions as the silicon nitride plate and a thickness of 1.0 mm were prepared.

Then, the composite plate is interposed between each of the silicon nitride plates and each of the carbon steel plates according to the dimensions of the respective silicon nitride plates,
After sandwiching a 10 μm-thick Ag foil and a 3 μm-thick Ti foil between the silicon nitride plate and the composite plate and between the composite plate and the carbon steel plate and superposing them, the same treatment as in Example 2 was performed to obtain 9 types of nitriding. A silicon-carbon steel joining member was obtained.

The appearance (presence or absence of cracks in the silicon nitride plate) of each of the obtained joint members was observed. The results are also shown in Table 3 above. In addition, in Table 3, except that instead of the composite plate, a phosphorus deoxidized copper (JIC C1221P) plate having the same dimensions as those composite plates was used,
The appearance observation result of the silicon nitride-carbon steel joint member obtained by the same method as in Example 9 is also shown as Comparative Example 7.

As is clear from Table 3 above, even if the bonding surface of the silicon nitride plate in Example 9 has a large area of ^□ 130 mm, cracking does not occur, and the particle dispersion strengthened composite plate (Cu-3% by weight) is used.
A high thermal stress relaxation effect due to Al ₂ O ₃ ) is observed. On the other hand, in the case of Comparative Example 7, the bonding surface of the silicon nitride plate was ^□ 20.
Cracks do not occur only up to mm, but cracks occur at larger areas.

〔The invention's effect〕

As described in detail above, according to the present invention, the bonding strength at high temperature is high, and the cracking of ceramics due to the heat effect (particularly the cracking on the bonding surface of a large area) can be prevented.
As a result, a highly reliable ceramic-metal joining member useful as various structural members and functional members can be provided.

[Brief description of drawings]

The drawings are characteristic diagrams obtained by measuring the shear strength by applying temperature to the joint surfaces of the silicon nitride-carbon steel joint members of Example 1 and Comparative Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiromitsu Takeda, 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa Incorporated Toshiba Research Laboratories (56) References JP-A-60-65773 (JP, A) Kaisho 60-246279 (JP, A)

Claims (1)

[Claims] 1. A ceramics-metal bonding surface is bonded with a particle dispersion strengthening type composite layer interposed, and the composite layer has a porosity of 1 to 30% by volume and a particle dispersion rate of 2 to 2 in a matrix metal. Ceramics characterized by being 12% by volume
Metal joining member.