JP2979529B2 - Joint of ceramic member and metal member - Google Patents

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 in which a ceramic member and a metal member are brazed.

[0002]

2. Description of the Related Art In recent years, lightweight ceramic members having excellent heat resistance, corrosion resistance and abrasion resistance, and high strength and workability have been used as mechanical parts used in various industrial machinery under high loads and high temperature atmospheres. Attention has been paid to a composite structure combining an excellent metal member, and various joined members of a ceramic member and a metal member have been proposed.

[0003] Conventionally, as a joined body of a ceramic member and a metal member, a metallized process is applied to a joined portion of a polished ceramic member, and a cut or cut metal member is closely attached or fitted to the joined portion and brazed. A joined body in which a metal member is shrink-fitted to a ceramic member has been widely used.

[0004] In particular, when a ceramic member and a metal member are used as a shaft joint, a metallization process is applied to the convex portion of the polished ceramic member, and the convex portion is inserted into a concave portion of the cut metal member. In general, a joined body in which the projections of the ceramic member are in contact with or shrink-fitted to the depressions of the metal member has been used.

However, such a joined body has problems such as a decrease in joining strength due to a difference in thermal expansion between the ceramic member and the metal member, and a breakage of the ceramic member or the metal member. In order to solve the above problem, it has been proposed to interpose a thermal stress relaxation body as an intermediate layer between a ceramic member and a metal member (Japanese Patent Publication No. 2-43704, Japanese Patent Application Laid-Open No. 2-19675). reference).

[0006]

However, in the above joined body, the stress difference between the two members due to the difference in thermal expansion is considerably reduced by the interposition of the intermediate layer used as a thermal stress relaxation body for the ceramic member and the metal member. However, in the circumferential direction of the metal member forming the concave portion, a tensile stress is generated in a cooling process after heating in the joining step, and the tensile stress changes due to a temperature change during use.

[0007] Further, in a state where such tensile stress is applied in the circumferential direction of the metal member, the joined body is applied to, for example, a joined body of a ceramic turbo rotor and a rotating shaft of a supercharger of an internal combustion engine, and is heated to a high temperature. When used for a long time in a high-temperature oxidizing atmosphere in which the temperature of the joint is around 400 ° C. due to heat conduction from the exhaust gas, cracks are generated on the outer peripheral surface due to grain boundary oxidation of the metal member surface of the joint. Finally, there is a problem that the metal member constituting the joined body is damaged.

[0008]

The joined body of the ceramic member and the metal member according to the present invention comprises a ceramic member having an average thermal expansion coefficient of 5 × 10 ⁻⁶ / ° C. or less from 20 ° C. to 400 ° C. 500 ° C containing Co, Nb and Si
A stress rupture life when a load stress of 50 kg / mm ² is applied in the atmosphere of not less than 80 hours is inserted into a concave portion of a metal member made of a precipitation-strengthened alloy with a clearance of 10 to 100 μm, The present invention is characterized in that the clearance is filled with a silver braze and brazed and joined, and the present invention is characterized in that another metal member is joined to the metal member side.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. FIG. 1 is a partially cutaway view showing a main part of an example in which a joined body of a ceramic member and a metal member according to the present invention is applied to a shaft coupling.

[0010] In FIG. 1, 1 is the average thermal expansion coefficient of up to 20 ° C. to 400 ° C. is 5 × 10 ^- a ceramic member ⁶ / ° C. or less, at least Ni, C ceramic member 1
o, Nb and Si, 50K in air at 500 ° C
Stress rupture when a load stress of g / mm ² is applied
A metal member 2 made of a precipitation-strengthened alloy having a life of 80 hours or longer is fitted into a concave portion 3 formed at one end of a metal member 2 and brazed.

[0011] The above ceramic member has a temperature of 20 ° C to 400 ° C.
° C. until an average thermal expansion coefficient of 5 × 10 of ^{- 6} / ° C. traversal, also unless flexural strength of at least 500 ° C. is 200MPa or more, various types of industrial machinery, which is used for a long time under high load and a high-temperature oxidizing atmosphere The ceramic member of the mechanical component in the above is inferior in practical use due to poor high-temperature strength and oxidation resistance. That is, silicon nitride (Si ₃ N) is used as the ceramic member.
₄ ), silicon carbide (SiC) and the like are preferably used.

On the other hand, the Ni and Co elements contained in the precipitation-strengthened alloy constituting the metal member both act to reduce or suppress the coefficient of thermal expansion of the precipitation-strengthened alloy.
The b element is intended to increase the strength by precipitating a compound by heat treatment after bonding with the Ni element. In addition, when a constant tensile load is applied to a test piece as a load stress in a constant atmosphere and in a constant atmosphere under a constant atmosphere, the life of a stress rupture test in which a metal member is evaluated by the time until the test piece breaks is extended. It contributes to.

Further, if the stress rupture life under the above-mentioned condition is less than 80 hours, the above-mentioned precipitation strengthened alloy cannot maintain a stable bonding state for a long time as a bonded body of a ceramic member and a metal member. It is not suitable as a metal member of a mechanical component in an industrial machine.

(Example 1) In evaluating a joined body of a ceramic member and a metal member of the present invention, silicon nitride (Si ₃
N ₄ ) as a main component, and yttria (Y ₂
A silicon nitride sintered body containing O ₃ ) and tungsten oxide (WO ₃ ) is ground to a diameter of 13 mm and a length of 30 mm.
A cylindrical ceramic member 1 as shown in FIG.

On the other hand, the composition, precipitation strengthening heat treatment conditions, and crystal grain size were variously set, and a precipitation strengthened alloy having a stress rupture life as shown in Table 1 measured according to the ASTM-E292 standard was used. The metal member 2 having an outer diameter of 18 mm and a length of 30 mm was manufactured by cutting so that the inner diameter of the concave portion in which is inserted was within a range of 10 to 100 μm with respect to the ceramic member.

Next, one end of the ceramic member 1 is inserted into the concave portion 3 of the metal member 2 and then brazed using a silver solder of BAg-8 standard to obtain a joined body of the ceramic member and the metal member for evaluation. Was.

The thus obtained joint body of the ceramic member and the metal member for evaluation, each of which is 50 pieces, is placed in a heating furnace at 500 ° C. in the air, which is more severe than the temperature condition at the time of use.
After leaving for 00 hours, the number of cracks in the metal member was examined by visual inspection and fluorescence penetrant inspection to evaluate the joined body. Table 1 shows the above results.

[0018]

[Table 1]

As can be seen from Table 1, the longer the stress rupture life, the lower the probability of cracking of the metal member when it is joined to a ceramic member, and
Stress rupture when a load stress of 50 Kg / mm ² is applied in the atmosphere of the above, the joined body with a ceramic member using a metal member having a life of 80 hours or more, the metal member does not crack at all. It can be seen that a very stable bonding state can be maintained over a long period of time.

(Embodiment 2) A silicon nitride based sintered body,
The convex part 4 of the radial type ceramic rotor, which is the ceramic member 1 as shown in FIG. 2, is joined to the rotating shaft 5 made of chromium molybdenum steel at, for example, an electron beam welding or the like at the joint position 6 shown in FIG. Ni 38.2% by weight, Co 13% by weight, Nb 4.98% by weight and Si
Table 1, consisting of a precipitation strengthened alloy containing 0.4% by weight,
After fitting into the recess 3 of the metal member 2 of the sample No. 6, BAg
A ceramic rotor joined body was manufactured by brazing using a -8 standard silver solder.

The thus-obtained ceramic rotor joined body was subjected to a high-temperature rotation test at 200,000 revolutions per minute at a gas temperature of 950 ° C. for 300 hours.

Similarly, when a high-temperature rotation test was performed on the ceramic rotor joined body using the sample No. 2 in Table 1 as the metal member 2 under the same conditions as described above, the ceramic rotor joined body took 161 hours. A break occurred due to cracking. Similarly, sample number 4 was assigned to metal member 2
The ceramic rotor joined body used as the above did not break until 300 hours, but fine cracks were observed on the outer peripheral surface of the metal member 2.

[0023]

As described above, in the joined body of the ceramic member and the metal member of the present invention, the ceramic member having an average thermal expansion coefficient of 5 × 10 ⁻⁶ / ° C. or less at 20 ° C. to 400 ° C. , Co, Nb and Si at 500 ° C.
A stress rupture life when a load stress of 50 kg / mm ² is applied in the atmosphere of not less than 80 hours is inserted into a concave portion of a metal member made of a precipitation-strengthened alloy with a clearance of 10 to 100 μm, The clearance is filled with silver braze and brazed to join, so that the ceramic member constituting the joined body is maintained while maintaining high joining strength, as well as no cracking of the metal member occurs, and oxidation resistance is maintained. It is possible to provide a joined body of a ceramic member and a metal member which is excellent in durability and durability, in particular, can be used continuously for a long time in a high-temperature oxidizing atmosphere.

[Brief description of the drawings]

FIG. 1 is a partially broken view showing a main part of an example in which a joined body of a ceramic member and a metal member according to the present invention is applied to a shaft coupling.

FIG. 2 shows a main part of an example in which a joined body of a ceramic member and a metal member according to the present invention is obtained by joining a metal member to a radial type ceramic rotor and joining a rotating shaft as another metal member to the metal member. FIG.

[Description of Signs] 1 ceramic member 2 metal member 3 concave portion 4 convex portion 5 rotating shaft 6 joining position

Claims (2)

(57) [Claims] 1. A ceramic member having an average coefficient of thermal expansion of 5 × 10 ⁻⁶ / ° C. or less from 20 ° C. to 400 ° C.
i, Co, Nb and Si, in a recess of a metal member made of a precipitation-strengthened alloy having a stress rupture life of 80 hours or more when a load stress of 50 kg / mm ² is applied in the air at 500 ° C. , Clear run of 10-100 μm
And then insert and insert silver braze into the above clearance
Conjugate of ceramic and metal members, characterized in that the brazed to. 2. A ceramic member having an average thermal expansion coefficient of 5 × 10 ⁻⁶ / ° C. or less from 20 ° C. to 400 ° C.
i, Co, Nb and Si, in a recess of a metal member made of a precipitation-strengthened alloy having a stress rupture life of 80 hours or more when a load stress of 50 kg / mm ² is applied in the air at 500 ° C. , Clear run of 10-100 μm
And then insert and insert silver braze into the above clearance
And then brazed to further assembly of the ceramic member and the metal member to the metal member side, characterized in that it has joined the other metal member.