JPH06254723A - Junction body, its combination body with ceramic, and their manufacture - Google Patents

Abstract

PURPOSE:To prevent the unbalanced change and breakage of a junction body such as a rotary shaft operated for a long period at a high speed and a high temperature by bonding a quenched metal member having specific hardness and a deposition hardening low-thermal expansion metal having specific strength to obtain the desired junction body. CONSTITUTION:A ceramic turbine rotor 12 provided with multiple blades 12b on the outer periphery of a solid hub 12a and a rotary shaft 13 formed with a metal shaft 14 and a sleeve 15 as a junction body are bonded to constitute a turbo charger rotor 11 as a combination body. A metal shaft 14 quenched while gas is used as a cooling medium and having the hardness of HRC 28 or above and a deposition hardening low-thermal expansion metal having the 0.2% yield strength of 500 Mpa or above are integrally bonded by friction pressure welding or electron beam welding, a recess is formed on the end face of the low-thermal expansion metal, and two ring grooves 15a, 15b are machined on the outer periphery of the sleeve 15 of the rotary shaft 13. The shaft 12c of the turbine rotor 12 is pressed into the recess of the sleeve 15 and integrated.

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 metal and another metal, a joined body of the joined body and ceramics, and a method for producing them. INDUSTRIAL APPLICABILITY The joined body of the present invention can be suitably used for a rotary shaft of a turbocharger rotor or a rotary shaft of a gas turbine rotor. Further, the combined body of the present invention can be suitably used for a turbocharger rotor or a gas turbine rotor.

[0002]

2. Description of the Related Art A ceramic body having excellent mechanical strength, heat resistance and abrasion resistance and a small specific gravity is used as a mechanical component used as a rotating body in a high temperature atmosphere such as a turbocharger or a gas turbine engine. (Sintered body of silicon nitride, sialon, silicon carbide, etc.) is suitable.

Therefore, a structure in which a metal is compounded or bonded to the above ceramic to compensate for the brittleness of the ceramic is generally used. By the way, since the ceramics and the metal have large thermal expansion coefficients, considerable strain remains in the vicinity of the joint due to the large difference in thermal expansion. This distortion causes damage to the brittle ceramics. In order to prevent this, a low-expansion metal having a coefficient of thermal expansion close to that of the ceramic is interposed as a buffer layer between the ceramic and the metal to be bonded and bonded.

In this case, fitting or chemical adhesion is used as a method for joining the ceramic and the low thermal expansion metal. Mating is, for example, press-fitting, shrink-fitting, and cold-fitting, and chemical bonding is brazing with active brazing or silver brazing. As a method of joining the low thermal expansion metal and the metal member, welding such as friction welding, electron beam welding, and laser welding is used.

The low thermal expansion metal is used in a precipitation hardened state. This is because unless it is precipitated and hardened, it cannot bear the load when it is bonded to ceramics or when it is used as a high-temperature high-speed rotating body. Further, the metal member is usually quenched at about 1000 ° C., and then about 300-
What is tempered at 600 ° C. is used. This is because without hardening and tempering, the bearing will not have sufficient hardness.

[0006]

Conventionally, when friction-welding a low-thermal-expansion metal and a metal member, even if the low-thermal-expansion metal is precipitation-hardened and the metal member is quenched and tempered before friction-welding. The heat of friction welding causes the low thermal expansion metal to be in a solution state, and its strength is significantly reduced. On the other hand, after quenching and tempering the metal member in advance, and friction-welding this with a low thermal expansion metal,
When the precipitation hardening treatment of the low thermal expansion metal is performed, the metal member becomes dull at the precipitation hardening treatment temperature (usually about 700 ° C.), and there is a problem that the strength of the metal member is significantly reduced.

Further, precipitation hardening treatment is performed after friction welding.
After that, a method of partially quenching and tempering by high frequency is also attempted, but performing heat treatment such as quenching and tempering completely up to the friction welding part has a heat treatment temperature higher than the solution temperature of the low thermal expansion metal. It was difficult because.
Therefore, there is a problem that a portion having low strength remains in the low expansion metal near the friction welding portion. Moreover, the process is long, which is disadvantageous in terms of cost.

Further, a method of electron beam welding a pre-precipitation-hardened low thermal expansion metal and a hardened / tempered metal member may be considered, but this method also causes the precipitation-hardened portion around the welded portion to be generated by the heat generated during welding. There was a problem that the solution became a solution and a problem that a residual stress due to welding occurred as well as a change in the metal structure around the weld. These phenomena are not only a problem in terms of strength, but also in the case of a rotating body that is operated at high speed and at high temperature for a long time, such as a rotor of a turbocharger or a rotor of a gas turbine, the problem of the rotating body is lost. There is a possibility that serious problems may occur in reliability such as increased balance, abnormal noise, increased vibration, and damage to the impeller and bearings.

The present inventors have solved this problem by using a low thermal expansion precipitation hardening type metal which can secure strength only by slowing the cooling rate during heat treatment, and a metal member which has hardness even if the cooling rate is slow. I found what I could do. An object of the present invention is to solve the conventional problems described above and to provide a joined body of a high-strength low thermal expansion metal and a high-hardness metal member. Another object of the present invention is to provide a bonded body in which such a bonded body and ceramics are firmly bonded.

[0010]

[Means for Solving the Problem] The first means is a metal member having a hardness of H _{RC of} 28 or more, which is hardened by using a gas as a cooling medium, and a 0.2% proof stress of 50% which is joined to the metal member.
A joined body comprising a precipitation hardening type low thermal expansion metal of 0 MPa or more.

A second means is a metal member having a hardness of H _{RC of} 28 or more, which is hardened by using a gas as a cooling medium, and a precipitation hardening type low thermal expansion metal which is joined to the metal member and has a 0.2% proof stress of 500 MPa or more. A bonded body of a ceramic and a ceramic bonded to the precipitation hardening type low thermal expansion metal.

The first means for producing the joined body of the present invention is
After welding a quenchable metal member using a gas as a cooling medium and a precipitation hardening type low thermal expansion metal, the metal member is heated to the quenching temperature or higher, and then the average cooling rate between 850 ° C. and 550 ° C. is 50 ° C. / It is characterized in that it is cooled in a gas so as to be less than a minute.

Similarly, in the second manufacturing means, a brazing material is interposed between a metal member capable of quenching using gas as a cooling medium and a precipitation hardening type low thermal expansion metal, and the metal member is heated to the quenching temperature or higher, and then 850 It is characterized by cooling in a gas so that the average cooling rate between 50 ° C. and 550 ° C. is 50 ° C./min or less.

The first means for producing the conjugate of the present invention is
After welding a quenchable metal member using a gas as a cooling medium and a precipitation hardening type low thermal expansion metal, the metal member is heated to the quenching temperature or higher, and then the average cooling rate between 850 ° C. and 550 ° C. is 50 ° C. / It is characterized in that it is cooled in a gas so that the amount becomes equal to or less than a minute, and further the ceramics is fitted to the precipitation hardening type low thermal expansion metal by fitting.

Similarly, in the second manufacturing means, a brazing material is interposed between the metal member capable of quenching using gas as a cooling medium, the precipitation hardening type low thermal expansion metal and the ceramics, and the metal member is heated to the quenching temperature or higher. After that, from 850 ℃ to 5
It is characterized by cooling in a gas so that the average cooling rate up to 50 ° C. is 50 ° C./min or less.

Here, the average cooling rate between 850 ° C. and 550 ° C. being 50 ° C./min or less means that the cooling rate may be changed, but the average value of the cooling rate in that temperature range is 50 ° C./min. It means setting to be less than or equal to minutes. Therefore, for example, a cooling operation may be performed such that the temperature from 850 ° C. to near the precipitation hardening temperature is cooled relatively quickly, the temperature is kept near the precipitation hardening temperature for a certain period of time, and then the temperature is cooled to 550 ° C.

[0017]

[Function] The precipitation hardening treatment of the low thermal expansion metal is generally 720 ° C.
8 hr-620 ° C. 8 hr, but as a result of investigating the relationship between the cooling rate and the strength of the low thermal expansion metal, as shown in FIG. 1, the cooling rate from 850 ° C. to 550 ° C. was 50 ° C. /
It was found that if it is less than or equal to the minute, 500 MPa can be secured with a 0.2% proof stress. Desirably, if the cooling rate is set to 5 ° C./minute or less, strength that is almost the same as that obtained by the ordinary precipitation hardening treatment can be obtained. SNCM-630, SNCM-616, and metal members that can obtain hardness at these cooling rates,
SUH-616, SUS-420, etc. are suitable.

Therefore, these annealing-treated metal members and solution-treated low-thermal-expansion metals are friction-welded,
After being integrated by welding such as electron beam welding or laser welding, the metal member is heated to the quenching temperature, then 8
If the cooling rate between 50 ° C. and 550 ° C. is adjusted to 50 ° C./min or less and cooled, the strength of the low thermal expansion metal is 50
A joined body having a hardness of 0 MPa or more and a metal member hardness of H _RC 28 or more can be obtained.

Therefore, a recess is formed in the low-thermal-expansion metal after joining, or the low-expansion metal is processed into a sleeve or bag shape before joining, and the shaft portion of the ceramic impeller is press-fitted or shrink-fitted into the recess. If they are combined with each other, a turbocharger and a gas turbine with excellent reliability can be manufactured. Further, the metal member, the low thermal expansion metal and the ceramic are roll-bonded near the quenching temperature of the metal member, and the cooling rate after the roll is 8
If the temperature is 50 ° C./min or less between 50 ° C. and 550 ° C., the strength of the low thermal expansion metal is 500 MPa only in the rolling treatment step.
A metal / ceramic bonded body having a hardness of the metal member of H _RC 28 or more can be obtained.

It should be noted that the low thermal expansion metal portion is 5 in order to withstand stress, vibration and centrifugal force at the time of joining when integrated with ceramics.
Is required above MPa, also metallic member is required for more than H _RC 28 in anti-friction when used as a bearing portion. Hereinafter, description will be given based on examples.

[0021]

【Example】

[Embodiment 1] FIG. 2 is a diagram showing an attempt to manufacture a joined body of the joined body of Example 1 and ceramics.
The combined body 11 is a turbocharger rotor, and is formed by combining the ceramics 12 and the joined body 13.

The ceramic 12 is a solid hub 12a.
And a plurality of blades 12b spirally provided on the outer periphery of the hub 12a, and a shaft 12c protrudingly provided on the back surface of the hub 12a, and having a density of 3.2.
It was integrally manufactured from a 0 g / cm ³ silicon nitride sintered body. The outer diameter of the blade 12b is 55 mm, the shaft 12c
Has an outer diameter of 12 mm.

The joint body 13 is the rotating shaft of the turbocharger rotor and transmits the rotational driving force of the turbine rotor to the compressor wheel. The joined body 13 includes a long metal shaft 14 and a substantially cup-shaped sleeve 15. The metal shaft 14 and the sleeve 15 are joined together by abutting each other on their end faces. The metal shaft 14 is supported by a bearing (not shown) and a compressor wheel (not shown).
Connect to. The sleeve 15 has an oil ring groove 1 on the outer circumference.
5a and the seal ring groove 15b are processed, and when the joined body 13 is joined to the ceramics 12, the metal shaft 14
And an intermediate member between the ceramics 12 and the ceramics 12.

A method of manufacturing this turbocharger rotor will be described below. Outer diameter 1 made of Incoloy 903
Outer diameter 1 consisting of 7mm low thermal expansion metal and SNCM630
The 1.0 mm metal shaft 14 was joined by friction welding.
Then, an inner diameter of 12 mm and a depth of 8.
A groove of 5 mm and two ring grooves were machined on the outer peripheral surface to form a sleeve 15. Thus, the joined body 13
(Rotating shaft) was manufactured.

Next, after holding this joined body 13 at 900 ° C. for 30 minutes, it was cooled in the furnace from 900 ° C. to 500 ° C. at an average cooling rate of 3 ° C./min. When the heat treatment was performed on the low thermal expansion metal of the same quality as the sleeve 15 and the metal member of the same quality as the metal shaft 14 under the same conditions as this heat treatment, the former 0.2% proof stress was 950 MPa and the latter hardness was H _RC 45. It was Finally, the shaft 12c of the ceramic 12 is press-fitted into the recess of the sleeve 15 with a press-fitting margin of 70 μ, and the turbocharger rotor is rotated.
Finished in the shape of.

[Embodiment 2] The joined body produced under the same conditions as in Embodiment 1 was held at 900 ° C for 30 minutes, and then, 900 ° C to 5 ° C.
The furnace was cooled to 00 ° C. at an average cooling rate of 45 ° C./min.
When the heat treatment was performed on the low thermal expansion metal of the same quality as the sleeve of this joined body and the metal member of the same quality as the metal shaft under the same conditions as this heat treatment, the 0.2% proof stress of the low thermal expansion metal was 550 M.
Pa, the hardness of the metal member was H _RC 47. Finally, the shaft 12c of the ceramic 12 was press-fitted into the recess of the sleeve 15 at a press-fitting margin of 70 μm to finish the shape of a turbocharger rotor.

[Embodiment 3] FIG. 3 is a diagram showing an attempt to manufacture a joined body of the joined body and ceramics of the third embodiment. The combined body 21 is a turbocharger rotor, and the ceramics 22 and the joined body 23 are combined.

The ceramic 22 is a turbine rotor of the same shape and quality as the ceramic 12 of the first embodiment. The joined body 23 is the rotating shaft of the turbocharger rotor as in the first embodiment, and includes the metal shaft 24 and the sleeve 25. However, a convex portion 24a is provided on the end surface of the metal shaft 24, and a through hole 25c is provided on the end surface of the sleeve 25 correspondingly. Then, the metal shaft 24 and the sleeve 25 are fitted together with the convex portion 24a and the through hole 25c fitted together.
And are joined.

The method of manufacturing this turbocharger rotor will be described below. A low thermal expansion metal made of Incoloy 909 was previously machined into a cup shape having a through hole 25c to form a sleeve 25. Through hole 2 of sleeve 25
The convex portion of the metal shaft 24 made of SUH-616 was fitted to 5c, and electron beam welding was performed in this state to integrate the sleeve 25 and the metal shaft 24. Thus, the joined body 23 was manufactured.

Next, the recess 25b of the sleeve 25 was filled with a brazing material, and the shaft portion 22c of the ceramic 22 was fitted therein. In the fitted state, the bonded body 23 and the ceramics 22 are 105
After holding at 0 ° C. for 1 hour, the joined body 23 and the ceramics 22 were brazed by a schedule with a roller for cooling from 1000 ° C. to 550 ° C. at a cooling rate of 5 ° C./min. Thus, a turbocharger rotor was manufactured. still,
The low thermal expansion alloy of the same quality as the sleeve 25 and the metal member of the same quality as the metal shaft 24 were subjected to heat treatment under the same conditions as the above-mentioned schedule with a roll, respectively.
The proof stress was 900 MPa, and the hardness of the metal member was H _RC 50.

[Comparative Example 1] A bonded body produced under the same conditions as in Example 1 was held at 900 ° C for 30 minutes, and then, 900 ° C to 5 ° C.
The inside of the furnace was cooled to 00 ° C. at an average cooling rate of 200 ° C./min. A low thermal expansion metal of the same quality as the sleeve of this joined body and a metal member of the same quality as the metal shaft were subjected to heat treatment under the same conditions as this heat treatment, and the 0.2% proof stress of the low thermal expansion metal was 40%.
The hardness of the metal member was 0 MPa, and the hardness was H _RC 46. Finally, the shaft 12c of the ceramic 12 was press-fitted into the recess of the sleeve 15 at a press-fitting margin of 70 μm to finish the shape of a turbocharger rotor.

[Comparative Example 2] The material of the metal shaft 14 is SNCM.
A turbocharger rotor was manufactured under the same conditions as in Example 1 except that SNCM439 was used instead of 630. The strength of the low thermal expansion metal at this time is 950MPa with 0.2% proof stress.
a, the hardness of the metal member was H _RC 25.

[Comparative Example 3] A turbocharger rotor was manufactured under the same conditions as in Comparative Example 2, and after heat treatment, only the metal shaft was quenched and tempered by a high frequency heating device to obtain H _RC 40.
And the hardness. However, quenching and tempering treatment could not be performed within 2 mm from the friction welding portion. This is because if the quenching / tempering process is performed to a position closer to the friction welded portion, the low thermal expansion metal may become a solution.

[Comparative Example 4] A sleeve 15 having the same shape and quality as in Example 1 was held in vacuum at 720 ° C for 8 hours, and then at a speed of 6.
After cooling at 0 ° C./hr and holding at 620 ° C. for 8 hours, the comparative sleeve was subjected to precipitation hardening treatment by cooling to room temperature. Then, the shaft portion 12c of the ceramic 12 was press-fitted into the recess with a press-fitting margin of 80 μ, and then quenching / tempering treatment was performed. Then, the metal shaft 14 having a hardness of H _RC 35 was welded to the end surface of the sleeve 15 by an electron beam to manufacture a rotor for comparison. Finally this
The machine was machined to a finished shape. The strength of the low thermal expansion metal in the vicinity of the welded portion of this turbocharger rotor was 400 MPa.

[Experimental Example] Table 1 shows a summary of parts materials, cooling rates and characteristics of Examples 1 to 3 and Comparative Examples 1 to 4. These turbocharger rotors are installed in the turbocharger and attached to a 2500cc engine.
Minute idling-5 minutes 1/2 load 2500 rpm-
5 minutes 4/4 load 6000 rpm (turbo rotation speed max
After carrying out a durability test in which three cycles of 150,000 rpm) were repeated for 10 hours, the change in the amount of imbalance was examined.

As shown in FIG. 3, the unbalanced measurement positions are the head T and the back plate H of the ceramics 22 (12). The measurement results are shown in Table 1.

[Table 1] As shown in Table 1, those to which the present invention is applied as in Examples 1 to 3 can suppress the change or breakage of the rotational balance as compared with Comparative Examples 1 to 4 to which the present invention is not applied. It was

From these results, it can be seen that the strength of the low thermal expansion metal must be 0.2 MPa at a strength of 500 MPa or more, and the metal member hardness must be H _RC 28 or more. When the strength of the low thermal expansion metal is lower than 500 MPa, the change in imbalance is large, and when the hardness of the metal member is lower than H _RC 28, the wear of the bearing part is increased, which leads to the damage of the rotor. Not preferable.

[0038]

As described above, the joined body of the present invention is
The low thermal expansion metal has high strength required for strong bonding with ceramics, and the metal member has high hardness to withstand abrasion with bearings and the like. Therefore, when the combined body with ceramics is used as a rotating body, the change in imbalance is small, the possibility of breakage is small, and the reliability is excellent.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a cooling rate of a low thermal expansion metal and 0.2% proof stress.

FIG. 2 is a diagram showing a state in which a bonded body of the bonded body and ceramics of Example 1 is to be manufactured.

FIG. 3 is a diagram showing a state where an attempt is made to produce a combined body of the joined body and ceramics of Example 2.

[Explanation of reference numerals] 11,21 Combined body (turbocharger rotor) 12,22 Ceramics (turbine rotor) 13,23 Bonded body (rotating shaft) 14,24 Metal shaft (metal member) 15,25 Sleeve (low thermal expansion metal)

Claims (13)

[Claims] 1. A metal member having a hardness of H _{RC of} 28 or more, which is hardened by using a gas as a cooling medium, and a precipitation hardening type low thermal expansion metal which is joined to the metal member and has a 0.2% proof stress of 500 MPa or more. Characterized zygote. 2. The joined body according to claim 1, wherein the metal member and the precipitation hardening type low thermal expansion metal are joined by friction welding, electron beam welding, laser welding or brazing. 3. A turbocharger rotor having the joint body according to any one of claims 1 and 2 as a rotation axis. 4. A gas turbine rotor having the joint body according to claim 1 as a rotating shaft. 5. A metal member having a hardness of H _{RC of} 28 or more, which is quenched by using a gas as a cooling medium, a precipitation hardening type low thermal expansion metal having a 0.2% proof stress of 500 MPa or more and joined to the metal member, and the precipitation hardening A bonded body of ceramics and ceramics bonded to a low thermal expansion metal. 6. A turbocharger rotor comprising a joined body of the joined body according to claim 5 and ceramics. 7. A gas turbine rotor comprising a joined body of the joined body according to claim 5 and ceramics. 8. A metal member that can be hardened by using gas as a cooling medium and a precipitation hardening type low thermal expansion metal are welded, then heated to a temperature not lower than the hardening temperature of the metal member, and then from 850 ° C. to 55.
A method for producing a joined body, which comprises cooling in a gas so that an average cooling rate up to 0 ° C. is 50 ° C./minute or less. 9. The method for producing a joined body according to claim 8, wherein the welding is any one of friction welding, electron beam welding and laser welding. 10. A metal member that can be hardened by using gas as a cooling medium and a precipitation hardening type low thermal expansion metal are welded, then heated to a temperature not lower than the hardening temperature of the metal member, and then 850 ° C. to 5 ° C.
A joined body and ceramics, characterized by cooling in a gas so that the average cooling rate up to 50 ° C. is 50 ° C./min or less, and further bonding the ceramics to the precipitation hardening type low thermal expansion metal by fitting. A method for producing a conjugate. 11. The method for producing a joined body of a joined body and ceramics according to claim 10, wherein the welding is friction welding, electron beam welding or laser welding. 12. A brazing material is interposed between a metal member that can be hardened by using gas as a cooling medium and a precipitation hardening type low thermal expansion metal, and after heating to a hardening temperature of the metal member or higher, 850
A method for producing a joined body, which comprises cooling in a gas so that an average cooling rate between 50 ° C. and 550 ° C. is 50 ° C./minute or less. 13. A brazing material is interposed between a metal member capable of quenching using gas as a cooling medium, a precipitation hardening type low thermal expansion metal and ceramics, and the metal member is heated to a temperature not lower than the quenching temperature and then 850 ° C. to 550 ° C. A method for producing a bonded body of a bonded body and ceramics, which comprises cooling in a gas so that an average cooling rate up to ° C is 50 ° C / minute or less.