JP3179928B2 - Bonded body, bonded body thereof and ceramics, and methods of manufacturing them - 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 metal and another metal, a joined body of the joined body and a ceramic, and a method of producing the same. The joined body of the present invention can be suitably used for a rotating shaft of a turbocharger rotor or a rotating 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 Mechanical parts used as a rotating body in a high-temperature atmosphere, such as a turbocharger or a gas turbine engine, are ceramic bodies having excellent mechanical strength, heat resistance and wear resistance and low specific gravity. (A sintered body such as silicon nitride, sialon, or silicon carbide) is suitable.

[0003] 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 coefficient of thermal expansion differs greatly between ceramics and metal, considerable distortion remains near the joint due to the large expansion difference. This distortion causes the fragile ceramics to break down. In order to prevent this, a low-expansion metal having a thermal expansion coefficient close to that of the ceramics is joined by interposing a buffer layer between the ceramics to be joined and the metal.

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

[0005] The low thermal expansion metal is used in a precipitation hardened state. If precipitation hardening does not occur, it cannot withstand the load during joining with ceramics or when used as a high-temperature high-speed rotating body. The metal member is usually quenched at about 1000 ° C.,
What has been tempered at 600 ° C. is used. Unless quenching and tempering are performed, sufficient hardness as a bearing is not provided.

[0006]

Conventionally, when a low thermal expansion metal and a metal member are friction-welded to each other, the low thermal expansion metal may be subjected to a precipitation hardening process and the metal member may be quenched and tempered before the friction welding. In addition, the heat during friction welding causes the low thermal expansion metal to be in a solution state, and its strength is significantly reduced. On the other hand, the metal member is quenched and tempered in advance, and after friction-welding this to the low thermal expansion metal,
When the precipitation hardening treatment is performed on the low thermal expansion metal, 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, a precipitation hardening treatment is performed after the friction welding,
Thereafter, a method of partially performing quenching and tempering by high frequency has also been attempted, but performing heat treatment such as quenching and tempering completely up to the friction welding portion requires a heat treatment temperature higher than the solution heat temperature of the low thermal expansion metal. Because it was difficult.
Accordingly, there is a problem that a low strength portion remains in the low expansion metal near the friction welding portion. Moreover, the process is long and disadvantageous in cost.

[0008] Furthermore, a method of electron beam welding of a low thermal expansion metal which has been precipitation hardened in advance and a quenched and tempered metal member can be considered. In this method, too, a precipitation hardened portion around a welded portion is formed by heat generated during welding. The problem of solution solution and the change of the metal structure around the welded portion and the problem of residual stress due to welding occurred. These phenomena occur not only in terms of strength, but also in the case of a rotating body that is operated at high speed and at a high temperature for a long time, such as a rotor for a turbocharger or a gas turbine. There is a possibility that a serious problem in reliability such as an increase in balance, an increase in abnormal noise, an increase in vibration, and a breakage of a wheel and a bearing may occur.

The inventors have solved this problem by using a low-thermal-expansion precipitation hardening metal which can secure strength only by slowing down the cooling rate during heat treatment, and a metal member which is hard even if the cooling rate is slow. I found what I could do. An object of the present invention is to solve the above-mentioned conventional problems 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 a ceramic are firmly bonded.

[0010]

The first means is that a metal member having a hardness of _HRC 28 or more, which is quenched using gas as a cooling medium, is joined to the metal member and has a 0.2% proof stress of 50%.
A joined body comprising a precipitation hardening type low thermal expansion metal of 0 MPa or more.

The second means is a metal member having a hardness of _HRC 28 or more quenched by using a gas as a cooling medium, and a precipitation hardening type low thermal expansion metal joined to the metal member and having a 0.2% proof stress of 500 MPa or more. And a ceramic joined with the ceramic, which is made of 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 as follows.
After welding the hardenable metal member and the precipitation hardening type low thermal expansion metal using the gas as a cooling medium, the metal member is heated to a temperature higher than the quenching temperature of the metal member, 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.

[0013] Similarly, the second production means comprises heating a metal member at a temperature higher than the quenching temperature of the metal member by interposing a brazing material between the metal member capable of being quenched using gas as a cooling medium and the precipitation hardening type low thermal expansion metal, It is characterized in that cooling is performed in a gas such 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 comprises:
After welding the hardenable metal member and the precipitation hardening type low thermal expansion metal using the gas as a cooling medium, the metal member is heated to a temperature higher than the quenching temperature of the metal member, 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 reduce the temperature to less than one minute, and furthermore, the ceramic is bonded to the precipitation hardening type low thermal expansion metal by fitting.

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

The reason that the average cooling rate between 850 ° C. and 550 ° C. is 50 ° C./min or less means that the cooling rate may be changed, but the average value of the cooling rate in the temperature range is 50 ° C./min. Minutes. Therefore, for example, a cooling operation may be performed in which cooling is performed relatively quickly between 850 ° C. and the vicinity of the precipitation hardening temperature, maintained for a certain time near the precipitation hardening temperature, and then cooled to 550 ° C.

[0017]

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

Therefore, these metal members subjected to the annealing treatment and the low thermal expansion metal subjected to the solution treatment are subjected to friction welding,
After being integrated by welding such as electron beam welding or laser welding, it is heated to the quenching temperature of the metal member, and then
If the cooling rate between 50 ° C. and 550 ° C. is adjusted so as to be 50 ° C./min or less and the cooling is performed, the strength of the low thermal expansion metal becomes 50%.
A joined body in which the metal member has a hardness of _HRC 28 or more with 0 MPa or more is obtained.

Therefore, a recess is formed in the low-thermal-expansion metal after joining, or the low-expansion metal is processed into a sleeve-like or tubular shape before joining, and the shaft of the ceramic impeller is press-fitted or shrink-fitted into the recess. If combined, 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 brazed near the quenching temperature of the metal member, and the cooling rate after the brazing is set to 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 by the brazing process,
Hardness of the metal member is bonded body of H _RC 28 or more metals and ceramic is obtained.

The low-thermal-expansion metal part is formed to withstand the stress, vibration and centrifugal force at the time of joining when it is integrated with the ceramic.
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 made based on embodiments.

[0021]

【Example】

[Embodiment 1] FIG. 2 is a view showing a state in which a combined body of the joined body of Embodiment 1 and ceramics is to be manufactured.
The combined body 11 is a turbocharger rotor in which the ceramics 12 and the joined body 13 are combined.

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 protruding from the rear surface of the hub 12a. The turbine rotor has a density of 3.2.
It was manufactured integrally with a silicon nitride based sintered body of 0 g / cm ³ . The outer diameter of the wing 12b is 55 mm, the shaft 12c
Has an outer diameter of 12 mm.

The joint 13 is a 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 butted and joined together at 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 its outer periphery.
5a and the seal ring groove 15b are machined, so that the metal shaft 14
And a ceramic 12.

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

Next, after holding the joined body 13 at 900 ° C. for 30 minutes, the inside of the furnace was cooled from 900 ° C. to 500 ° C. at an average cooling rate of 3 ° C./min. The metal member of the low thermal expansion metal and metal shaft 14 and the same quality of the sleeve 15 of the same quality, was heat-treated under the same conditions as the heat treatment, a 0.2% yield strength of the former is 950 MPa, the latter hardness H _RC 45 met Was. Finally, the shaft 12c of the ceramics 12 is press-fitted into the recess of the sleeve 15 with a press-fitting allowance of 70 μm.
Finished in shape.

Example 2 A joined body manufactured under the same conditions as in Example 1 was held at 900.degree.
The furnace was cooled down to 00 ° C at an average cooling rate of 45 ° C / min.
When a low thermal expansion metal of the same quality as the sleeve of the joined body and a metal member of the same quality as the metal shaft were subjected to heat treatment under the same conditions as the heat treatment, the 0.2% proof stress of the low thermal expansion metal was 550M.
Pa, the hardness of the metallic member was H _RC 47. Finally, the shaft 12c of the ceramics 12 was press-fitted into the concave portion of the sleeve 15 with a press-fitting allowance of 70 μm to finish in the form of a turbocharger rotor.

[Embodiment 3] FIG. 3 is a view showing a state in which a combined body of the joined body and the ceramic of the embodiment 3 is to be manufactured. The combined body 21 is a turbocharger rotor, and is formed by combining the ceramics 22 and the joined body 23.

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

Hereinafter, a method of manufacturing the turbocharger rotor will be described. A low thermal expansion metal made of Incoloy 909 was machined in advance into a cup shape having a through-hole 25 c to obtain a sleeve 25. Through hole 2 in 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 22c of the ceramics 22 was fitted. The bonded body 23 and the ceramics 22
After holding at 0 ° C. for 1 hour, the joined body 23 and the ceramics 22 were brazed by a schedule with a roll for cooling from 1000 ° C. to 550 ° C. at a cooling rate of 5 ° C./min. Thus, a turbocharger rotor was manufactured. still,
A low thermal expansion alloy of the same quality as the sleeve 25 and a metal member of the same quality as the metal shaft 24 were subjected to heat treatment under the same conditions as the above-described low-scheduled schedule.
Yield strength 900 MPa, hardness of the metallic member was H _RC 50.

Comparative Example 1 A joined body manufactured under the same conditions as in Example 1 was held at 900.degree.
The furnace was cooled to 00 ° C at an average cooling rate of 200 ° C / min. When 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 the heat treatment, the 0.2% proof stress of the low thermal expansion metal was 40%.
0 MPa, the hardness of the metallic member was H _RC 46. Finally, the shaft 12c of the ceramics 12 was press-fitted into the concave portion of the sleeve 15 with a press-fitting allowance of 70 μm to finish in the form of a turbocharger rotor.

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

[0033] [Comparative Example 3] to produce a turbocharger rotor under the same conditions as Comparative Example 2, the metal shaft only in the high-frequency heating apparatus performs quenching and tempering treatment after the heat treatment, H _RC 40
Hardness. However, quenching and tempering treatment could not be performed between 2 mm from the friction welded portion. This is because if the quenching / tempering treatment is performed to a position closer to the friction welding portion, the low thermal expansion metal may be turned into a solution.

[Comparative Example 4] A sleeve 15 having the same shape and the same shape as in Example 1 was held at 720 ° C in a vacuum 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 sample was cooled to room temperature to perform a precipitation hardening treatment of the comparative sleeve. Next, after the shaft portion 12c of the ceramics 12 was press-fitted into the concave portion with a press-fitting allowance of 80 μm, a quenching / tempering process was performed. Thereafter, the metal shaft 14 having a hardness of _HRC 35 was welded to the end face of the sleeve 15 by an electron beam to manufacture a comparative rotor. Finally this row
The finisher was finished to a finished shape by machining. The strength of the low thermal expansion metal near the weld of the turbocharger rotor was 400 MPa.

[Experimental Examples] Table 1 summarizes the component materials, cooling rates and characteristics of Examples 1 to 3 and Comparative Examples 1 to 4. These turbocharger rotors are incorporated into a turbocharger and attached to a 2500 cc engine.
Minute idling-5 minutes 1/2 load 2500 rpm-
4/4 load for 5 minutes 6000 rpm (turbo rotation speed max)
After a durability test in which three cycles of 150000 rpm were repeated for 10 hours, a change in the amount of unbalance was examined.

As shown in FIG. 3, the measurement positions of the unbalance are at two places, the head T and the back plate H of the ceramics 22 (12). Table 1 shows the measurement results.

[Table 1] As shown in Table 1, the case where 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 where the present invention is not applied. Was.

From these results, it is understood that the low thermal expansion metal needs to have a strength of 500 MPa or more at a 0.2% proof stress and a metal member hardness of _HRC 28 or more. When the intensity of the low thermal expansion metal is lower than 500MPa it has a large change in the imbalance, and if the hardness of the metal member is lower than H _RC 28 is increased wear of the bearing portion, Russia - data - damage leads to the Not preferred.

[0038]

As described above, the joined body of the present invention is:
The low thermal expansion metal has a high strength required for a strong bond with the ceramics, and the metal member has a high hardness to withstand abrasion with a bearing or the like. Therefore, when the combined body with the ceramics is used as a rotating body, there is little change in unbalance and there is little possibility of breakage, resulting in an excellent reliability.

[Brief description of the drawings]

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

FIG. 2 is a view showing a state in which a combined body of the joined body and ceramics of Example 1 is to be manufactured.

FIG. 3 is a view showing a state in which a joined body of a joined body and ceramics of Example 2 is to be manufactured.

[Explanation of symbols]

 11,21 Combined body (turbocharger rotor) 12,22 Ceramics (turbine rotor) 13,23 Bonded body (rotary shaft) 14,24 Metal shaft (metal member) 15,25 Sleeve (low thermal expansion metal)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-270275 (JP, A) JP-A-4-97967 (JP, A) JP-A-3-69570 (JP, A) JP-A-4-70 89368 (JP, A) JP-A-2-124781 (JP, A) JP-A-1-215769 (JP, A) JP-A-61-215270 (JP, A) JP-A-5-9085 (JP, A) JP-A-5-85846 (JP, A) JP-A-2-56918 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C04B 37/02 B23K 1/00-20/26 B23P 11/00

Claims (13)

(57) [Claims] 1. A metal member having a hardness of _HRC 28 or more quenched by using a gas as a cooling medium and a precipitation hardening type low thermal expansion metal joined to the metal member and having a 0.2% proof stress of 500 MPa or more. Characterized joints. 2. The joined body according to claim 1, wherein the metal member and the precipitation hardening low thermal expansion metal are joined by friction welding, electron beam welding, laser welding, or brazing. 3. A turbocharger rotor having the joined body according to claim 1 as a rotation axis. 4. A gas turbine rotor having the joined body according to claim 1 or 2 as a rotating shaft. 5. A metal member quenched by using a gas as a cooling medium and having a hardness of _HRC 28 or more, a precipitation hardening type low thermal expansion metal joined to the metal member and having a 0.2% proof stress of 500 MPa or more, and the precipitation hardening What is claimed is: 1. A bonded body of a bonded body and ceramics, comprising a ceramic bonded to a mold low thermal expansion metal. 6. A turbocharger rotor comprising a combined body of the joined body according to claim 5 and ceramics. 7. A gas turbine rotor comprising a combination of the joined body according to claim 5 and ceramics. 8. After welding a hardenable metal member and a precipitation hardening type low thermal expansion metal using a gas as a cooling medium, the metal member is heated to a temperature higher than the quenching temperature of the metal member, and then heated from 850 ° C. to 55 ° C.
A method for producing a joined body, wherein cooling is performed in a gas such that an average cooling rate up to 0 ° C. is 50 ° C./min or less. 9. The method according to claim 8, wherein the welding is any one of friction welding, electron beam welding, and laser welding. 10. After welding a quenching metal member and a precipitation hardening type low thermal expansion metal using a gas as a cooling medium, the metal member is heated to a temperature higher than the quenching temperature of the metal member and then from 850 ° C. to 5 ° C.
Cooling in a gas so that the average cooling rate up to 50 ° C. is 50 ° C./min or less, and further bonding the ceramic to a precipitation hardening type low thermal expansion metal by fitting, Method for producing a conjugate. 11. The method according to claim 10, wherein the welding is any one of friction welding, electron beam welding, and laser welding. 12. After heating to a temperature equal to or higher than the quenching temperature of the metal member by interposing a brazing material between the metal member capable of being quenched using the gas as a cooling medium and the precipitation hardening type low thermal expansion metal, the temperature is increased to 850 or more.
A method for producing a joined body, wherein cooling is performed in a gas such that an average cooling rate between 50 ° C and 550 ° C is 50 ° C / min or less. 13. After heating the metal member to a temperature higher than the quenching temperature of the metal member by interposing a brazing material between the metal member capable of being quenched using the gas as the cooling medium, the precipitation hardening type low thermal expansion metal and the ceramic, respectively, A method for producing a combined body of a joined body and ceramics, wherein cooling is performed in a gas such that an average cooling rate up to 50 ° C. is 50 ° C./min or less.