JPH0891952A - Ceramic member-metallic member conjugate - Google Patents

Abstract

PURPOSE: To obtain the subject highly durable conjugate usable continuously for a long time over a wide range of temperatures, retaining high joint strength from low to high temperatures, causing the ceramic member not to slip off owing to the deformation of the brazing metal layer even if subjected to external force in a high-temperature atmosphere. CONSTITUTION: This conjugate is obtained by jointing, through brazing, a ceramic member 2 to a metallic member 3 via an intermediate layer 4 with its thermal expansion coefficient greater than that of the metallic member 3 by >=4.0×10<-6> / deg.C. In this conjugate, the thickness 7 of the intermediate layer 4 stands at <=0.50 times that 8 of the metallic member, there is no brazing metal at the boundary 5 between the intermediate layer 4 and the metallic layer 2 and there is a brazing metal 6 between the intermediate layer 4 and the ceramic member 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joined body of a ceramic member and a metal member suitable for various rotary bodies used in a high temperature atmosphere such as a gas turbine and a turbocharger.

[0002]

2. Description of the Related Art In recent years, a mechanism used in various industrial machines and equipment such as chemical plants and machine tool parts, and various power engines such as gas turbines and turbochargers, which is exposed to a high load and high temperature atmosphere. As parts, various ceramics having excellent heat resistance, corrosion resistance and wear resistance, high strength and small specific gravity have been widely used.

Under such circumstances, since the above-mentioned ceramics are brittle materials, it is difficult to apply them to a portion where bending stress is repeatedly applied, and moreover, they are poor in workability.
It has been noticed that the composite structure is a combination of ceramic and metal, such that only the part exposed to high temperature is made of ceramics, and the part on which high load acts is made of metal member with high strength and excellent workability. As a result, various bonded bodies have been proposed.

The composite structure in which the ceramic and the metal are combined is diffusion-bonded by using a brazing material containing an active metal, shrink-fitted by using a low thermal expansion alloy having a thermal expansion coefficient close to that of ceramics, or press-fitted. What was done was widely used.

However, in such a joined body,
When the operating temperature is relatively low, the strain caused by the difference in thermal expansion between the ceramics and the metal and the contraction force of the metal have a small effect on the ceramics or the metal itself, but the stress is high under a high temperature atmosphere of 600 ° C or higher. May occur, or the joining force may be reduced to withstand use, and if an external force is applied, there is a risk of peeling from the joining interface or destruction of the ceramics or the metal itself.

Therefore, in order to eliminate the difference in thermal expansion between the ceramics and the metal and maintain the high bonding strength up to a high temperature, a thermal stress relaxation body made of a metal having a low thermal expansion coefficient or a low Young's modulus is provided between the ceramics and the metal. Various proposals have been made such as intervening as an intermediate layer or joining via an intermediate layer which is a thermal stress relaxation layer in which the coefficient of thermal expansion continuously changes between ceramics and metal (Japanese Patent Publication No. 6-60065). (See Japanese Utility Model Publication No. 2-20189).

[0007]

However, as shown in FIG. 3, the thermal stress relaxation body made of the metal having the low thermal expansion coefficient or the low Young's modulus is used as the intermediate layer 9, and the ceramic 10 and the metal are interposed via the intermediate layer 9. When 11 is joined, the strain generated by thermal expansion due to elastic deformation or plastic deformation of the intermediate layer 9 is absorbed, but when a brazing material is used for joining, it is If the brazing layer 12 is thermally deformed and excessive stress is applied thereto, the brazing layer 12 may be further deformed, or in the worst case, the joint interface may be peeled off. However, there is a problem that the joining force between the joining members is reduced in a high temperature atmosphere, and the strength of the intermediate layer 9 itself at high temperatures is not sufficient.

In the case where the thermal stress relaxation layer whose thermal expansion coefficient changes continuously is used as the intermediate layer, since the intermediate layer is formed by plasma spraying or the like, it is sufficient to relax the residual stress generated at the time of joining. There is a problem in that it is difficult to form a sufficient thickness, and in a high temperature atmosphere, thermal stress increases due to the difference in thermal expansion between the ceramic and the intermediate layer, and the ceramic is damaged.

[0009]

SUMMARY OF THE INVENTION The present invention has been made as a solution to the above-mentioned problems, and it maintains high bonding strength from low temperature to high temperature and does not cause deformation of the brazing material layer even when external force acts in a high temperature atmosphere. To obtain a joined body of a ceramic member and a metal member, which has excellent durability capable of continuous use over a wide temperature range for a long time and is particularly suitable for a rotating body in which a ceramic shaft and a metal shaft are joined. It is a thing.

[0010]

In the joined body of the ceramic member and the metal member of the present invention, the coefficient of thermal expansion between the ceramic member and the metal member is greater than that of the metal member by 4.0 × 10 ⁻⁶ / ° C. or more. An intermediate layer is provided and brazed, and the thickness of the intermediate layer is 0.50 or less of the thickness of the metal member that abuts on the opposite side of the ceramic member through the intermediate layer, and It is shrink-fitted and joined to the metal member, and there is no brazing material on its abutting surface, and at the same time, the brazing material is filled in at least the gap formed between the intermediate layer and the ceramic member. It is characterized by.

In particular, the thickness of the intermediate layer interposed between the ceramic member and the metal member is 0.13 to 0.about the thickness of the metal member abutting on the opposite side of the ceramic member through the intermediate layer.
33 is more preferable.

When the difference between the coefficient of thermal expansion of the intermediate layer and that of the metal member is less than 4.0 × 10 ⁻⁶ / ° C., the control width of the gap between the intermediate layer and the metal member becomes narrow, and The degree of interference fit is weak due to the small difference in thermal expansion between the intermediate layer and the metal member during brazing, and the brazing material easily penetrates during that, and the high temperature bonding strength typified by high temperature punching strength, for example, deteriorates. become.

Further, at high temperature, the ceramic member may fall off or come out of the metal member, especially when the temperature rises to 700 ° C. or above, the brazing material softens and the brazing material yields, and thereafter, between the brazing material and the intermediate layer. It is caused by the occurrence of slip, and it is desirable to interpose the brazing material as thin as possible.

Further, since the brazing material layer has an extremely large influence on the bonding strength, the brazing material layer is not formed into a plurality of layers as much as possible, and the difference in the coefficient of thermal expansion is used to the contrary to directly bond the intermediate layer and the metal member. It is essential.

On the other hand, the gap between the intermediate layer and the ceramic member is
Although it depends on the brazing temperature, when using a high-temperature brazing material which will be described later, 0.15 μm or less on one side is desirable.

Next, regarding the relationship between the thickness of the intermediate layer and the thickness of the metal member, when the thickness of the intermediate layer exceeds 0.50 of the thickness of the metal member, the intermediate layer affects the strength of the joint. Since the intermediate layer itself has a large strength deterioration at a high temperature, the fastening force decreases, which is not preferable.

[0017]

In the joined body of the ceramic member and the metal member of the present invention, an intermediate layer having a coefficient of thermal expansion larger than that of the metal member by 4.0 × 10 ⁻⁶ / ° C. or more is provided between the ceramic member and the metal member. Since the brazing material is not present in the contact surface between the intermediate layer and the metal member, the brazing material is filled and intervenes at least in the gap formed between the intermediate layer and the ceramic member. In a high-temperature atmosphere, the intermediate layer tightens the ceramic member through the brazing material having the largest coefficient of thermal expansion, and the intermediate layer having a coefficient of thermal expansion larger than that of the metal member adheres so as to spread the metal member, The surface pressure of the joint increases and high joint strength is maintained, and the brazing filler metal filled in the gap exhibits a cushioning effect so that the strength at the joint starting point does not deteriorate.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a joined body of a ceramic member and a metal member according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a partially cutaway view of an essential part of an embodiment showing a joined body of a ceramic member and a metal member according to the present invention, and FIG. 2 shows a joined body of a ceramic member and a metal member according to the present invention. FIG. 4 is a partially cutaway view of a main part showing an example applied to a joined body of a ceramic rotor and a metal rotating shaft used in a gas turbine, a turbocharger, or the like.

In FIGS. 1 and 2, 1 is an intermediate portion between the ceramic member 2 and the metal member 3 in which the coefficient of thermal expansion is greater than that of the metal member 3 by 4.0 × 10 ⁻⁶ / ° C. or more. In a joined body of a ceramic member and a metal member brazed via the layer 4, the thickness 7 of the intermediate layer is 0.50 or less of the thickness 8 of the metal member, and the thickness of the intermediate layer 4 and the metal member 2 is equal to or less than 0.50. The brazing material is not interposed in the contact surface 5, but the brazing material 6 is filled and interposed in the gap between the intermediate layer 4 and the ceramic member 2.

Particularly, the thickness 7 of the intermediate layer is preferably 0.13 to 0.33 which is the thickness 8 of the metal member.

As the ceramic member, mechanical parts typified by a ceramic rotor such as a gas turbine and a turbocharger are non-oxide type materials such as silicon nitride (Si ₃ N ₄ ), sialon and silicon carbide (SiC). Ceramics are preferred, but if the coefficient of thermal expansion in the temperature range from room temperature to 1000 ° C. is 5.0 × 10 ⁻⁶ / ° C. or less, it can be applied to either oxide-based or non-oxide-based ceramics. .

Further, the metal member may be from room temperature to 7
The coefficient of thermal expansion in the temperature range of 00 ° C is 13.0 × 10 ^-6
A low thermal expansion heat-resistant alloy excellent in high-temperature strength of less than / ° C, for example, heat-resistant steel of various iron-based alloys such as nickel-based alloys and cobalt-based alloys is preferable, and specifically from room temperature to 700 ° C. Coefficient of thermal expansion in the temperature range of 11.0
A precipitation-strengthened iron-based alloy typified by Incoloy 909 having a temperature of ˜12.0 × 10 ⁻⁶ / ° C., and a fiber-reinforced metal whose thermal expansion coefficient is controlled are also applicable.

On the other hand, as the intermediate member, from room temperature to 7
The coefficient of thermal expansion in the temperature range of 00 ° C is 17.0 × 10 ^-6
/ ° C. or more, stainless steel, matrix-strengthened nickel-base alloy, precipitation-strengthened nickel alloy, and the like are preferable, and specifically, the coefficient of thermal expansion in the temperature range from room temperature to 700 ° C. is 18.7 × 10 ^−6. / ℃ or above SUS304
Etc.

The brazing material used for joining is preferably a high temperature brazing material such as palladium brazing material such as BPd7 or nickel brazing material such as BNi-2, which does not soften below 900 ° C.

The brazing material filled and interposed in the gap between the intermediate layer and the ceramic member does not necessarily have to be directly adhered to the ceramic member, and may be simply an interference fit without being adhered. It does not affect performance.

Next, in evaluating the joined body of the ceramic member and the metal member of the present invention, the ceramic member contains silicon nitride (Si ₃ N ₄ ) as a main component and yttria (Y ₂ O) as a sintering aid. ₃ ), Alumina (Al ₂ O ₃ )
A columnar molded body formed by mixing and tungsten (W) and the like was fired in a nitrogen gas atmosphere to obtain a silicon nitride sintered body.

Next, the above-mentioned sintered body is polished with a diamond grindstone into two types of cylindrical shape having a diameter of 16 mm and 20 mm and a length of 40 mm, and various metal members such as precipitation-strengthened iron-based alloys are also used. Based on an outer diameter of 22.9 mm made of heat-resistant steel having a coefficient of thermal expansion, the thickness of the metal member is variously set as shown in Table 1, and the inner diameter is 5 to 20 μm as a difference from the outer diameter of the intermediate layer. 12m height set to
It was cut into a cylindrical shape of m.

On the other hand, as the intermediate layer, the outer diameter has a difference of 5 to 20 μm from the inner diameter of the metal member, and the inner diameter has a height of 8 mm set to have a difference from the outer diameter of the ceramic member of 10 to 20 μm. Cylindrical SUS304 of 13.7 mm and other alloys with various coefficients of thermal expansion are each 16 m in diameter.
m and 20 mm were prepared for the ceramic member.

As the coefficient of thermal expansion, a value of RT-950 ° C. was adopted.

After washing and degreasing each of the above members, an intermediate layer was fitted inside the metal member, and then the inner diameter side surface of the intermediate layer was plated with nickel.

Next, a cylindrical ceramic member was fitted inside the nickel-plated intermediate layer, and a high-temperature solder corresponding to the BPd7 standard was wound around the ceramic member protruding above the metal member, followed by brazing.

The brazing is heat-treated for 20 minutes at a temperature of 1080 ° C. in an argon (Ar) gas atmosphere using a vacuum furnace to melt and fill the gap between the ceramic member and the intermediate layer with the high-temperature brazing metal, The contact surface between the member and the intermediate layer is fastened in a shrink-fitted state by utilizing the thermal expansion difference without interposing the brazing material, and at least the gap between the intermediate layer and the ceramic member is filled with the brazing material. A bonded body of a ceramic member and a metal member for evaluation was prepared.

Using the thus obtained joint body for evaluation, a ceramic member protruding from a metal member was loosely fitted in a through hole provided in the base, and the base end supported the cylindrical end surface of the metal member at 700 ° C. At the measurement temperature of, the ceramic member was pressed from above to be punched into the through hole, and a punching test was performed to evaluate the bonding strength.

[0035]

[Table 1]

From the above results, sample numbers 22 and 23 in which a ceramic member and a metal member are directly bonded with a brazing material without providing an intermediate layer, and even if an intermediate layer is provided, sample numbers 1, 10, and 13 outside the present invention are provided. Both Nos. 20 and 20 have a punching strength of 1.9.
Whereas it is 5 kg / mm ² or less, it is seen that the punch strength conjugate Any 2.00 kg / mm ² or more in the present invention.

The bonded body of the present invention was subjected to a cantilever bending test in which the metal member was gripped and the tip of the ceramic member protruding from the metal member was pressed and bent at room temperature. It was confirmed that it has a cantilever bending strength of 7 kg / mm ² .

Further, similarly to the above-mentioned joined body for evaluation, a shaft portion of a radial type rotor made of a silicon nitride sintered body having a maximum outer diameter of 163 mm is provided with a precipitation strengthening iron-based alloy through an intermediate layer of SUS304. Of the heat-resistant steel rotating shaft, and the BPd7 is formed in the recessed hole formed so that the thickness ratio is 0.17.
A joined body of a ceramic rotor and a metallic rotating shaft made of a nickel-based alloy as shown in FIG. 2 joined by a high-temperature braze equivalent to the standard was subjected to a high-temperature high-speed rotation test at 950 ° C.
It was confirmed that the motor worked up to 55,000 rpm without any abnormality.

[0039]

As described above, the joined body of the ceramic member and the metal member of the present invention has a thermal expansion coefficient of 4.0 × 10 ⁻⁶ / ° C. or more between the ceramic member and the metal member. A large intermediate layer is provided for brazing, and no brazing material is present on the contact surface between the intermediate layer and the metal member, while at least the gap formed between the intermediate layer and the ceramic member is filled with brazing material and intervenes. Therefore, high bonding strength is maintained from low temperature to high temperature, and even if external force acts in a high temperature atmosphere, the brazing material layer does not deform and the ceramic member does not fall off, and it can be used in a wide temperature range. It has excellent durability that allows it to be used continuously for a long time, and it is used in various industrial machinery and power such as chemical plants and machine tool parts, as well as gas turbines, turbochargers, jet engines, and other high-temperature cyclic loads and impact loads. Institutions It is extremely useful as a mechanical component used.

[Brief description of drawings]

FIG. 1 is a partial cutaway view of an essential part of an embodiment showing a joined body of a ceramic member and a metal member according to the present invention.

FIG. 2 is a part of a main part showing an example in which the joined body of a ceramic member and a metal member according to the present invention is applied to a joined body of a ceramic rotor and a metal rotating shaft used in a gas turbine, a turbocharger or the like. FIG.

FIG. 3 is a cross-sectional view of essential parts of a bonded body in which a thermal stress relaxation body made of a metal having a low thermal expansion coefficient or a low Young's modulus is interposed as an intermediate layer between a conventional ceramic and a metal.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 ceramic member-metal member joined body 2 ceramic member 3 metal member 4 intermediate layer 5 contact surface 6 brazing material 7 intermediate layer thickness 8 metal member thickness

Claims (2)

[Claims] 1. In a joined body in which a ceramic member and a metal member are brazed to each other through an intermediate layer, the thickness of the intermediate layer at the joined portion is less than the thickness of the metal member abutting on the intermediate layer.
50 or less, the coefficient of thermal expansion of the intermediate layer is 4.0 × 10 ⁻⁶ / ° C. or more higher than the coefficient of thermal expansion of the metal member, and the brazing material is interposed on the contact surface between the intermediate layer and the metal member. A joined body of a ceramic member and a metal member, characterized in that a brazing material is present at least in the gap between the intermediate layer and the ceramic member. 2. The ceramic member according to claim 1, wherein the thickness of the intermediate layer at the joint is 0.13 to 0.33 of the thickness of the metal member abutting on the intermediate layer. A joined body of metal members.