JP2015209572A - Heat-resistant member, method for manufacturing heat-resistant member, alloy film, method for manufacturing alloy film, rocket engine, satellite and power generation gas turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant member capable of significantly improving high temperature corrosion resistance of a metal base material consisting of Nb, Nb-Hf based alloy or Nb-Si based alloy and excellent in heat resistance and durability, and a rocket engine using the heat-resistant member.SOLUTION: The heat-resistant member includes a metal base material 100 consisting of Nb, Nb-Hf based alloy or Nb-Si based alloy and an alloy film 500 formed on the surface thereof. An alloy film 500 comprises in order from the metal base material 100 side: a transition region 110 including a NbSiphase as a crystal phase; an inner layer 200 including a NbSiphase as a crystal phase; an intermediate layer 300 including a MSiphase (M is at least two or more kinds of elements selected from a group consisting of Fe, Cr, Al, Mo, W, Re and Hf) as a crystal phase; and an outer layer 400 including at least one kind of a ReSiphase and a Re(Al,Si)phase as a crystal phase.

Description

  The present invention relates to a heat-resistant metal member, a method for producing a heat-resistant metal member, an alloy film, a method for producing an alloy film, and a rocket engine, artificial satellite, and power generation gas turbine using the heat-resistant metal member or alloy film.

  Currently, niobium (Nb) -based alloys that are lightweight, have a high melting point, and are excellent in workability are used for rocket engines for satellite orbit conversion and attitude control. However, since the Nb-based alloy is inferior in high temperature oxidation resistance, it is necessary to improve the high temperature oxidation resistance.

Conventionally, in order to improve the high-temperature oxidation resistance of a substrate made of an Nb-based alloy, a technique of coating the surface of the substrate with a silicide compound having excellent high-temperature oxidation resistance has been employed (see Non-Patent Document 1). . According to Non-Patent Document 1, in this silicide coating, the outer layer and the diffusion layer are respectively MSi ₂ and M ₅ Si ₃ (both M is a general term for a refractory metal and typically Nb, and Si is silicon (silicon)). The oxidation resistance of Nb-based alloys is said to be achieved by the formation of silicon dioxide (SiO ₂ ) and composite oxides. Furthermore, Non-Patent Document 1 describes that in this silicide coating, cracks are present from the stage of film formation, but it does not reach the base material, so that a long life can be obtained under combustion conditions. Has been.

  On the other hand, in a rocket engine, Nb is laminated several times by chemical vapor deposition, and a cylindrical strength layer is formed, and iridium (Ir) and Nb are alternately chemical vapor deposited on the inner and outer peripheral surfaces of this strength layer. Combustion by an intermediate layer formed by laminating by the method and forming at least two layers of Ir and Nb, and a skin layer formed by laminating Ir several times on the inner and outer peripheral surfaces of this intermediate layer by chemical vapor deposition It has been proposed to form a chamber (see Patent Document 1). According to Patent Document 1, a multilayer coating in which Ir and Nb are alternately laminated can be applied to a combustion chamber of a radiation-cooled rocket engine whose surface temperature reaches 2000 ° C.

Further, in order to improve the high temperature oxidation resistance of a base material made of an Nb-titanium (Ti) alloy, this base material has a multilayer structure [first layer is (Nb, Ti, iron (Fe)) Si _2. The second layer is proposed to be coated with (Nb, Ti, Fe, chromium (Cr)) ₃ Si ₂ ] (see Patent Document 2).

Further, in order to improve the high-temperature oxidation resistance of a substrate made of an Nb-hafnium (Hf) -based alloy (C-103), Si powder, alumina (Al ₂ O ₃ ) powder, and sodium fluoride as an activator It has been reported that this base material is coated with a multilayer structure of NbSi ₂ and Nb ₅ Si ₃ by high Si activity siliconizing treatment using (NaF) (see Non-Patent Document 2). .

JP-A-10-54302 US Pat. No. 5,721,061 Japanese Patent No. 3904197 Japanese Patent No. 4271399 Japanese Patent No. 4323816 Japanese Patent No. 3944437

M.L. Chazen: Long Life 5 LBF Bipropellant Engines; AIAA'85 paper 1378 (AIAA / SAE / ASME / ASEE 21st Joint Propulsion Conference, July 8-10,1985, Monterey California) Md. Zafir Alam A. Sambasiva Rao Dipak K. Das; Microstructure and High Temperature Oxidation Performance of Silicide Coating on Nb-BasedAlloy C-103, Oxidation of Metals, 73 (2010), pp. 513-530 Ave Villajarevjesky, M. Stillin, and Bei Krasirov, high temperature corrosion and corrosion protection of ultra-high melting point metals Atom Publishing Co. 1977 p. 126

However, Non-Patent Document 1, the NbSi ₂ phase, when forming the SiO ₂ scaled by high temperature oxidation, change in Nb ₅ Si ₃ phase, rapidly-since the Nb ₅ Si ₃ phase poor in oxidation resistance Invite intense oxidation. In addition, the presence of cracks is undesirable because cracks present in the silicide coating layer reach the substrate and the substrate is directly oxidized at high temperature, leading to rapid oxidation.

  Further, in Patent Document 1, Ir has a high specific gravity and high cost, and further, interdiffusion between Nb and Ir proceeds at a high temperature, and a non-protective Nb oxide is formed when Nb reaches the surface. Loss of oxidation resistance is expected.

Also in the coating of Patent Document 2, when a SiO ₂ scale is formed by high temperature oxidation, (Nb, Ti, Fe) Si ₂ is a lower silicide, for example, (Nb, Ti, Fe) ₅ Si ₃ phase or (Ti , Fe) Si phase, and this (Nb, Ti, Fe) ₅ Si ₃ phase or (Ti, Fe) Si phase is inferior in oxidation resistance and thus causes rapid and intense oxidation.

Further, in Non-Patent Document 2, when SiO ₂ is formed by high-temperature oxidation, the NbSi ₂ phase changes to an Nb ₅ Si ₃ phase. As a result, it has been reported that a non-protective Nb oxide is formed and oxidation proceeds rapidly, and in particular, it is inferior in oxidation resistance under heating and cooling conditions.

  Therefore, the problem to be solved by the present invention is that a high temperature oxidation resistance of a metal substrate made of Nb—Hf base alloy, more generally a metal substrate made of Nb, Nb—Hf base alloy or Nb—Si base alloy. A long-life heat-resistant metal member and alloy film excellent in heat resistance and durability, a method for producing the same, and a rocket engine using the heat-resistant metal member or alloy film, It is to provide an artificial satellite and a gas turbine for power generation.

In order to solve the above problems, the present invention provides:
A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region containing an Nb ₅ Si ₃ phase as a crystal phase, an inner layer containing an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) A refractory metal member including an outer layer including at least one of _1.8 phases.

  Here, the Nb—Hf-based alloy or Nb—Si-based alloy constituting the metal substrate is a generic name for alloys containing Nb as a main component (main component) and containing Nb followed by Hf or Si. One or more of oxygen (O), carbon (C), and nitrogen (N) are inevitably included in the Nb, Nb—Hf-based alloy, or Nb—Si-based alloy.

  The transition region typically contains one or more elements other than Nb and Si depending on the type of metal substrate used and the raw materials used in the production of the refractory metal member.

  The inner layer typically includes Si of 46.3 atomic% or more and less than 67.5 atomic%, Nb of 26.2 atomic% or more and 35.2 atomic% or less, rhenium (Re), aluminum (Al), molybdenum ( At least one element selected from the group consisting of Mo), tungsten (W), titanium (Ti), chromium (Cr), hafnium (Hf), oxygen (O), carbon (C) and nitrogen (N). 10.8 atomic% or less is included, and the total amount of these elements is 100 atomic% or less. The elements contained in the inner layer vary depending on the type of metal substrate used and the raw materials used for the production of the heat-resistant metal member.

The intermediate layer typically includes an MSi ₂ phase (M is at least two elements selected from the group consisting of Fe, Cr, Al, Mo, W, Re, and Hf) as a crystalline phase. The intermediate layer may also contain at least one of a ReSi _1.8 phase and a Re (Al, Si) _1.8 phase as a crystal phase. The elements contained in the intermediate layer vary depending on the type of metal substrate used and the raw materials used for the production of the heat-resistant metal member.

It has been reported that the ReSi _1.8 phase contained in the outer layer is excellent in oxidation resistance in the atmosphere (see Non-Patent Document 3). The outer layer typically has Si of 33.1 atomic% or more and less than 68.1 atomic%, Al of 37.0 atomic% or less, Re of 6.7 atomic% or more and 41.1 atomic% or less, Nb, Mo , W, Ti, Cr, Hf, O, C, and N. At least one element selected from the group consisting of 16.3 atom% or less is included, and the total amount of these elements is 100 atom% or less. The elements contained in the outer layer vary depending on the type of metal substrate used and the raw materials used for manufacturing the heat-resistant metal member. Nb contained in the outer layer is preferably less than the viewpoint of suppressing the formation of non-protective Nb oxide, preferably 16.3 atomic% or less, more preferably 5.0 atomic% or less, most preferably 1.0 atomic percent or less.

There may be a boundary region between at least one of the transition region and the inner layer, between the inner layer and the intermediate layer, and between the intermediate layer and the outer layer. The boundary region between the transition region and the inner layer is a region where the transition region and the inner layer are combined, and typically includes an Nb ₅ Si ₃ phase and an NbSi ₂ phase. The boundary region between the inner layer and the intermediate layer is a region where the inner layer and the intermediate layer are combined, and typically includes an NbSi ₂ phase and an MSi ₂ phase. The boundary region between the intermediate layer and the outer layer is a region where the intermediate layer and the outer layer are combined, and is typically at least one of the MSi ₂ phase, the ReSi _1.8 phase, and the Re (Al, Si) _1.8 phase. Including.

  The transition region, the intermediate layer, and the outer layer are generally continuous layers, but the inner layer may be a continuous layer or a discontinuous layer. When the inner layer is a discontinuous layer, if there is a boundary region between the intermediate layer or the inner layer and the intermediate layer, the boundary layer partially penetrates into the inner layer and the inner layer is separated. Yes. In this state, it can be said that there is a region where the inner layer and the intermediate layer or the boundary region are mixed. At least a part of the intermediate layer exists outside the inner layer, but the intermediate layer may partially exist inside the inner layer.

In addition, this invention
Forming a layer containing Re on a metal substrate made of Nb, Nb—Hf-based alloy or Nb—Si-based alloy;
First Si diffusion penetration treatment at a temperature of 1600 ° C. or higher and 1650 ° C. or lower using a mixed powder of Nb ₅ Si ₃ phase powder and NbSi ₂ phase powder as a vapor source on the metal substrate on which the layer containing Re is formed A process of performing
A process for producing a heat-resistant metal member having the step of performing the second Si diffusion permeation treatment for 10 minutes or more at a temperature of 1300 ° C. or higher and 1350 ° C. or lower using the Si powder as a vapor source after the first Si diffusion permeation treatment is performed. is there.

The layer containing Re is formed by, for example, electroplating and / or applying a slurry in which a fine powder containing at least Re is mixed with an organic binder, but the method of forming the layer containing Re is not limited to these. If necessary, other conventionally known methods such as chemical vapor deposition (CVD using a source gas containing Re) or physical vapor deposition (vacuum vapor deposition, sputtering, etc.) may be used. When a layer containing Re is formed by electroplating, the layer containing Re may be a Re layer or a Re-containing alloy layer. The fine powder containing Re contains one or more elements selected from the group consisting of Mo, W, Cr, and Ti as necessary. The layer containing Re may be repeatedly formed by these methods. For example, after a layer containing Re is formed on a metal substrate by electroplating or slurry application, a layer containing Re may be formed again by electroplating or slurry application. First Si diffusion penetration treatment (hereinafter also referred to as “low Si activity diffusion treatment” if necessary) and second Si diffusion penetration treatment (hereinafter referred to as “high Si activity diffusion treatment” if necessary) Is also preferably performed for 10 minutes or more and 13 hours or less, more preferably within this range for 30 minutes or more, and even more preferably for 1 hour or more. The first Si diffusion penetration treatment and the second Si diffusion penetration treatment are performed in an inert gas atmosphere such as argon (Ar) or in vacuum, for example. By the first Si diffusion permeation treatment, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an intermediate layer, and an outer layer including a ReSi _1.8 phase are formed on the metal substrate. At this time, the alloy film can be densified and the occurrence of cracks in the alloy film can be prevented. At this time, the solid solution of Nb in the ReSi _1.8 phase constituting the outer layer can be suppressed to a negligible level, and the formation of non-protective Nb oxide can be prevented. Further, an inner layer containing an NbSi ₂ phase as a crystal phase is formed between the transition region and the intermediate layer by the second Si diffusion permeation treatment. Thus, in order from the metal substrate side, an alloy film including a transition region including the Nb ₅ Si ₃ phase as the crystal phase, an inner layer including the NbSi ₂ phase as the crystal phase, an intermediate layer, and an outer layer including the ReSi _1.8 phase as the crystal phase is formed. Is done. The heat-resistant metal member is produced by performing a second Si diffusion permeation treatment, if necessary, and then using a mixed powder of Al powder, Si powder, and SiC powder as a sintering inhibitor as a vapor source at 1300 ° C. or higher. It further includes a step of performing Al diffusion penetration treatment (hereinafter also referred to as “high Al activity diffusion treatment” as necessary) at a temperature of 1350 ° C. or less. The Al diffusion and penetration treatment is performed, for example, in an inert gas atmosphere such as argon (Ar) or in a vacuum. As a result of the preferential bonding of Al to Al in a part of the ReSi _1.8 phase included in the outer layer by Al diffusion permeation treatment, the Si in the ReSi _1.8 phase is replaced by Al and changed to the Re (Al, Si) _1.8 phase. . In this Al diffusion penetration treatment, the amount of Al dissolved in the NbSi ₂ phase is very small, and Al selectively binds to Re.

  Although a heat-resistant metal member is not specifically limited, Specifically, they are a member for rocket engines, a member for gas turbines, etc., for example.

In addition, this invention
A transition region including a Nb ₅ Si ₃ phase as a crystalline phase and a NbSi ₂ as a crystalline phase, which are formed on the surface of a metal substrate made of Nb, Nb—Hf-based alloy or Nb—Si-based alloy, in that order from the metal substrate side. The alloy film includes an inner layer including a phase, an intermediate layer, and an outer layer including at least one of a ReSi _1.8 phase and a Re (Al, Si) _1.8 phase as a crystal phase.

In addition, this invention
Forming a layer containing Re on a metal substrate made of Nb, Nb—Hf-based alloy or Nb—Si-based alloy;
First Si diffusion penetration treatment at a temperature of 1600 ° C. or higher and 1650 ° C. or lower using a mixed powder of Nb ₅ Si ₃ phase powder and NbSi ₂ phase powder as a vapor source on the metal substrate on which the layer containing Re is formed A process of performing
And performing a second Si diffusion penetration treatment for 10 minutes or more at a temperature of 1300 ° C. or more and 1350 ° C. or less using the Si powder as a vapor source after the first Si diffusion penetration treatment.

In addition, this invention
A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an inner layer including an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) A rocket engine including an outer layer including at least one of _1.8 phases.

In addition, this invention
Have at least one rocket engine,
The above rocket engine
A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an inner layer including an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) An artificial satellite including an outer layer including at least one of _1.8 phases.

In addition, this invention
A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an inner layer including an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) A power generation gas turbine having a moving blade including an outer layer including at least one of _1.8 phases.
In each of the inventions of the alloy film, the method of manufacturing the alloy film, the rocket engine, the artificial satellite, and the gas turbine for power generation, as long as it does not violate the nature, The explanation is valid.

In the above heat-resistant metal member, alloy film, rocket engine, artificial satellite and power generation gas turbine, the following phenomenon occurs when the alloy film is exposed to the corrosive atmosphere of high-temperature combustion gas. That is, when the outer layer comprises a Resi _1.8 phase, by Resi _1.8 phase, SiO ₂ film exhibiting excellent protective properties in corrosive atmosphere of the combustion gases on the surface of the alloy film is formed. Si concentration of Resi _1.8 phase by SiO ₂ film is formed is reduced, but since the NbSi ₂ phase contained in the inner layer to provide a Si becomes a source of Si in the outer layer through an intermediate layer, Resi _1.8 phase Retained. In this case, the NbSi ₂ phase contained in the inner layer changes to the Nb ₅ Si ₃ phase as a result of supplying Si to the outer layer. On the other hand, Al ₂ when the outer layer comprises a Re (Al, Si) _1.8 phase, the Re of (Al, Si) by _1.8 phase, exhibits excellent protection in corrosive atmosphere of the combustion gases on the surface of the alloy film An O ₃ film is formed. Re by Al ₂ O ₃ film is formed (Al, Si) Al concentration of _1.8 phase decreases, Re (Al, Si) is _1.8 phase of Al changes Resi _1.8 phase when depleted, the Resi _1.8 A SiO ₂ film is formed by the phase. As a result, when the alloy film is exposed to the corrosive atmosphere of high-temperature combustion gas, the alloy film and thus the metal substrate are protected by this SiO ₂ film or Al ₂ O ₃ film, so that the high temperature resistance of the metal substrate The oxidizability can be greatly improved. Also, excellent heat resistance and durability can be obtained.

  The present inventors have conducted intensive research in order to elucidate the mechanism by which the above-mentioned clever function obtained by the alloy film of the present invention is exhibited. As a result, the mechanism was clarified based on the Nb—Re—Si ternary phase diagram. The outline is as follows.

The Nb-Re-Si ternary phase diagram has not been published so far as the present inventors know, so it was originally created as follows. That is, first, mixed powders were prepared by using Re powder, Nb powder and Si powder having a purity of 99.9% or more as starting materials and blending these powders into various compositions. This mixed powder was melted in an argon arc melting furnace to produce a 10-20 gram massive alloy. This massive alloy was heat-treated at 1500 ° C. for 24 hours in a vacuum to homogenize the composition and the structure. Next, the massive alloy thus obtained is cut, and the structure near the center is observed, and the concentration of each element of Nb, Re, and Si is measured using a micro element analyzer (EPMA; Electron-Probe Micro Analyzer). Was measured. From these analysis results, the composition of phases adjacent to each other in the phase diagram (referred to as conjugate composition) is determined. These conjugated compositions were put together to determine an Nb—Re—Si ternary phase diagram as shown in FIG. In the course of this determination, a new Nb—Re—Si ternary alloy phase was found and named the Q phase. From Nb-Resi-based ternary phase diagram shown in FIG. 1, the three-phase region (T3 region of Figure 1) with Resi _1.8 phase and Nb ₅ Si ₃ phase and Q-phase, Resi _1.8 phase and Nb ₅ Si ₃ phase It can be seen that there are three-phase regions (T2 region in FIG. 1) of NbSi ₂ phase and NbSi ₂ phase, and three-phase regions (T1 region in FIG. 1) of ReSi _1.8 phase, NbSi ₂ phase and Si phase.

As described above, by using a mixed powder of Nb ₅ Si ₃ phase powder and NbSi ₂ phase powder as a vapor source for the first Si diffusion infiltration treatment, Nb is Nb ₅ Si ₃ phase and Re is ReSi _1.8 phase. Thus, it is understood that the region of T3 in FIG. 1 where the Q phase exists as an equilibrium phase with these Nb ₅ Si ₃ phase and ReSi _1.8 phase is obtained. On the other hand, when Si powder is used as the vapor source for the second Si diffusion permeation treatment as described above, Nb becomes the NbSi ₂ phase and Re becomes the ReSi _1.8 phase, and Nb is used as an equilibrium phase between these NbSi ₂ phase and ReSi _1.8 phase. The region of T2 in FIG. 2 where ₅ Si ₃ phase is present is obtained.

That is, in the first Si diffusion permeation treatment, the ReSi _1.8 phase and the Nb ₅ Si ₃ phase are formed, but the NbSi ₂ phase is not formed. On the other hand, in the second Si diffusion permeation treatment, ReSi _1.8 phase and NbSi ₂ phase can be formed. What should be noted here is that the ReSi _1.8 phase is formed in both the first Si diffusion penetration treatment and the second Si diffusion penetration treatment, and the solid solution of Nb in the ReSi _1.8 phase is suppressed to a negligible level. And formation of non-protective Nb oxide can be effectively suppressed.

In addition to the experiments for creating the Nb—Re—Si ternary phase diagram, the amounts of Al and Nb dissolved in the ReSi _1.8 phase were also measured. As a result, it was revealed that the Re (Si, Al) _1.8 phase was maintained until Al: Si = 1: 1, and the Nb concentration was 1 atomic% or less.

According to the heat-resistant metal member, alloy film, rocket engine, artificial satellite and power generation gas turbine according to the present invention, when the alloy film is exposed to the corrosive atmosphere of high-temperature combustion gas, the outer layer contains the ReSi _1.8 phase. In this case, a protective SiO ₂ film is formed on the surface of the alloy film, and when the outer layer contains a Re (Al, Si) _1.8 phase, a protective Al ₂ O ₃ film is formed on the surface of the alloy film until Al is depleted. After the formation and depletion of Al, a protective SiO ₂ film is formed, so that the high-temperature oxidation resistance of the metal substrate can be greatly improved, and excellent heat resistance and durability can also be obtained. . For this reason, a long-life heat-resistant metal member, a rocket engine, an artificial satellite, and a power generation gas turbine can be realized. Further, according to the method for producing a heat-resistant metal member and the method for producing an alloy film according to the present invention, such an excellent heat-resistant metal member and alloy film can be easily obtained by a conventionally known method without using a special method. Can be manufactured.

It is a Nb-Re-Si type | system | group ternary phase diagram which the present inventors created uniquely. It is sectional drawing which shows the heat resistant metal member by one Embodiment of this invention. 2 is a drawing-substituting photograph showing a cross-sectional structure of the test piece of Example 1 after a low Si activity diffusion treatment. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 3 is a drawing-substituting photograph showing a cross-sectional structure of the test piece of Example 1 after a high Si activity diffusion treatment for 1 minute. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 2 is a drawing-substituting photograph showing a cross-sectional structure of the test piece of Example 1 after addition of a high Si activity diffusion treatment for 1 hour. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 6 is a drawing-substituting photograph showing a cross-sectional structure in a completed state of the test piece of Example 2. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 4 is a drawing-substituting photograph showing a cross-sectional structure in a completed state of the test piece of Example 3. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 6 is a drawing-substituting photograph showing a cross-sectional structure in a completed state of the test piece of Example 4. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 6 is a drawing-substituting photograph showing a cross-sectional structure in a completed state of a test piece of Example 5. FIG. FIG. 16 is a schematic diagram illustrating a measurement result of concentration distribution of each element in a cross section of the test piece illustrated in FIG. 15. FIG. 10 is a drawing-substituting photograph showing a cross-sectional structure of a test piece subjected to application of slurry containing fine powder of Re and subsequent heat treatment in Example 6. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. FIG. 10 is a drawing-substituting photograph showing a cross-sectional structure of a test piece subjected to a low Si activity diffusion process in Example 6. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. FIG. 6 is a drawing-substituting photograph showing a cross-sectional structure of a test piece subjected to high Al activity diffusion treatment in Example 6. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 3 is a drawing-substituting photograph showing a cross-sectional structure of a test piece after performing high-temperature oxidation experiment 1. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 5 is a drawing-substituting photograph showing a cross-sectional structure of a test piece after performing high-temperature oxidation experiment 2. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 6 is a drawing-substituting photograph showing a cross-sectional structure of a test piece after performing high-temperature oxidation experiment 3. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. 6 is a drawing-substituting photograph showing a cross-sectional structure of a test piece after performing a high-temperature oxidation experiment 4. FIG. It is a basic diagram which shows the measurement result of the concentration distribution of each element in the cross section of the test piece shown in FIG. It is sectional drawing which shows the example which applied the heat-resistant metal member by one Embodiment of this invention to the combustor of a rocket engine.

  Hereinafter, modes for carrying out the invention (hereinafter simply referred to as “embodiments”) will be described.

[Heat-resistant metal member]
FIG. 2 shows a refractory metal member according to an embodiment of the present invention. As shown in FIG. 2, the heat-resistant metal member includes a metal substrate 100 made of Nb, Nb—Hf-based alloy or Nb—Si-based alloy, and an alloy film 500 formed on the surface of the metal substrate 100. Have The alloy film 500 includes a transition region 110, an inner layer 200, an intermediate layer 300, and an outer layer 400 in this order from the metal substrate 100 side.

The transition region 110 includes an Nb ₅ Si ₃ phase as a crystal phase, and is generally composed mainly of this Nb ₅ Si ₃ phase. The thickness of the transition region 110 is generally 10 to 100 μm, but is not limited thereto.

The inner layer 200 includes an NbSi ₂ phase as a crystal phase, and is generally composed mainly of this NbSi ₂ phase. The inner layer 200 typically has Si of 46.3 atomic% or more and less than 67.5 atomic%, Nb of 26.2 atomic% or more and 35.2 atomic% or less, Re, Al, Mo, W, Ti, Cr 10.8 atomic% or less of at least one element selected from the group consisting of H, O, C, and N, and the total amount of these elements is 100 atomic% or less. The thickness of the inner layer 200 is generally 5 to 30 μm, but is not limited thereto.

The intermediate layer 300 includes an MSi ₂ phase (M is at least two elements selected from the group consisting of Fe, Cr, Al, Mo, W, Re, and Hf) as a crystal phase, and further includes a ReSi _1.8 phase and a ReSi It may contain at least one of (Al, Si) _1.8 phase, and generally contains at least one of this MSi ₂ phase or ReSi _1.8 phase and Re (Al, Si) _1.8 phase in addition to this MSi ₂ phase. It is configured as. The thickness of the intermediate layer 300 is generally 10 to 50 μm, but is not limited thereto.

The outer layer 400 includes at least one of a ReSi _1.8 phase and a Re (Al, Si) _1.8 phase as a crystal phase, and generally includes at least one of the ReSi _1.8 phase and the Re (Al, Si) _1.8 phase. It is configured as a subject. The outer layer 400 typically includes Si of 33.1 atomic% or more and less than 68.1 atomic%, Al of 37.0 atomic% or less, Re of 6.7 atomic% or more and 41.1 atomic% or less, Nb, 16.3 atomic% or less of at least one element selected from the group consisting of Mo, W, Ti, Cr, Hf, O, C and N is contained, and the total amount of these elements is 100 atomic% or less. The thickness of the outer layer 400 is generally 10 to 30 μm, but is not limited thereto.

There may be a boundary region 199 in which the transition region 110 and the inner layer 200 are combined with each other between the transition region 110 and the inner layer 200, and the inner layer 200 and the intermediate layer 300 are between the inner layer 200 and the intermediate layer 300. There may be a boundary region 299 in which the layers 300 are combined with each other, and a boundary region 399 in which the intermediate layer 300 and the outer layer 400 are combined with each other may exist between the intermediate layer 300 and the outer layer 400. The boundary region 199 typically includes an Nb ₅ Si ₃ phase and an NbSi ₂ phase as crystal phases. The boundary region 299 typically includes an Nb ₅ Si ₃ phase and an NbSi ₂ phase as crystal phases. The boundary region 399 typically includes at least one of an MSi ₂ phase, a ReSi _1.8 phase, and a Re (Al, Si) _1.8 phase as a crystal phase.

  In FIG. 2, the interfaces between the layers constituting the heat-resistant metal member are depicted as planes, but each interface generally has a complicated form formed by a plane or a curved surface.

[Method for producing heat-resistant metal member]
The manufacturing method of this heat-resistant metal member is demonstrated.
First, a metal substrate 100 is prepared, and a layer containing Re is formed thereon. The layer containing Re may be electroplated with Re or a Re-containing alloy, applied with a slurry in which fine powder containing at least Re is mixed in an organic binder, or a combination of these, or repeated multiple times. To form.

Next, a low Si activity diffusion process is performed on the metal substrate 100 on which the layer containing Re is formed. Specifically, the metal substrate 100 in which a layer containing Re is formed is embedded in a mixed powder of Nb ₅ Si ₃ phase powder and NbSi ₂ phase powder in a crucible, and an inert gas atmosphere such as Ar Further, by heating at a temperature of 1600 ° C. or higher and 1650 ° C. or lower in a vacuum, the mixed powder is used as a vapor source to perform a diffusion and permeation treatment of Si. This low Si activity diffusion treatment is preferably performed for 10 minutes to 9 hours. By this low Si activity diffusion treatment, the transition region 110 including the Nb ₅ Si ₃ phase as the crystal phase, the intermediate layer 300, and the outer layer 400 including the ReSi _1.8 phase are formed on the metal substrate 100.

Next, a high Si activity diffusion process is performed on the metal substrate 100 that has been subjected to the low Si activity diffusion process as described above. Specifically, the metal substrate 100 that has been subjected to the low Si activity diffusion treatment is embedded in Si powder placed in a crucible, and the temperature is 1300 ° C. or higher and 1350 ° C. or lower in an inert gas atmosphere such as Ar or in vacuum. By heating, this Si powder is used as a vapor source to perform a diffusion and permeation treatment of Si. This high Si activity diffusion treatment is preferably performed for 10 minutes to 13 hours. By this high Si activity diffusion treatment, an inner layer 200 including an NbSi ₂ phase as a crystal phase is formed between the transition region 110 and the intermediate layer 300.

When the outer layer 400 includes the Re (Al, Si) _1.8 phase, the high Al activity diffusion treatment is further performed after the high Si activity diffusion treatment. Specifically, the metal substrate 100 subjected to the high Si activity diffusion treatment is embedded in a mixed powder of Al powder, Si powder, and SiC powder as a sintering inhibitor placed in a crucible, and 1300 in a vacuum. By heating at a temperature of not less than 1 ° C. and not more than 1350 ° C., Al diffusion and permeation treatment is performed using this mixed powder as a vapor source. By this high Al activity diffusion treatment, a part of the Si in the ReSi _1.8 phase contained in the outer layer is replaced by Al and changed to the Re (Al, Si) _1.8 phase.

  As described above, the alloy film 500 having at least a four-layer structure including the transition region 110, the inner layer 200, the intermediate layer 300, and the outer layer 400 is formed on the metal substrate 100, and the intended heat-resistant metal member is manufactured.

[Changes in alloy film when heat-resistant metal members are exposed to high-temperature combustion gas atmosphere]
When this refractory metal member is used in a high-temperature combustion gas atmosphere, when the outer layer 400 of the alloy film 500 exposed to the combustion gas atmosphere contains a ReSi _1.8 phase, a protective SiO ₂ film is formed on the surface. When the outer layer 400 contains a Re (Al, Si) _1.8 phase, a protective Al ₂ O ₃ film is formed, and this protective SiO ₂ film or the protective Al ₂ O ₃ film forms an alloy film 500 and eventually a metal. The substrate 100 is protected from the combustion gas atmosphere.

In the following examples, the steps used for forming the alloy film are as follows.
Step (1) Re plating: Re plating conforms to the method described in Patent Documents 3 to 6, and the thickness of the Re layer is 2 to 10 μm, preferably 2 to 5 μm.

Step (2) Slurry application: After applying a slurry in which fine powders of various metals (Mo, W, Re, Fe, Cr, Ti, etc.) are mixed in an organic binder to the surface of the metal substrate 100, 1300 ° C to 1500 ° C. Heat treatment is performed in a vacuum at 2 ° C. for 2 hours. The smaller the particle size of the fine powders of Mo and W, the better. However, from the viewpoint of ease of handling and cost, the porosity of the slurry film, etc., the particle size is suitably 0.1 to 5 μm, desirably 0.5. ~ 3 μm. The thickness of the slurry is 10 to 100 μm, desirably 15 to 50 μm. The reason why the heat treatment is performed at 1300 ° C. to 1500 ° C. is to promote densification of the applied slurry powder and to ensure adhesion between the metal substrate and the layer containing Re.

Step (3) Low Si activity diffusion treatment: Nb powder, Si powder and SiC particles as a sintering inhibitor are mixed at a weight ratio of Nb: Si: SiC = 7: 3: 10, and this mixed powder is mixed with a carbon crucible. And heat treatment is performed at a high temperature of 1600 ° C. to 1650 ° C. in an Ar gas atmosphere. At this time, Nb and Si in the mixed powder react with each other to form a mixed powder of Nb ₅ Si ₃ phase powder and NbSi ₂ phase powder. This mixed powder is called Nb-Si-SiC mixed powder, and this Nb-Si-SiC mixed powder is used for low Si activity diffusion treatment.

Step (4) High Si activity diffusion treatment: Si powder and SiC powder are mixed at a weight ratio of Si: SiC = 1: 1, and this mixed powder is loaded into a carbon crucible and 1300 ° C. to 1350 ° C. in a vacuum. The high Si activity diffusion treatment is performed by performing heat treatment under the conditions of 2 to 13 hours.

Step (5) High Al activity diffusion treatment: Al powder, Si powder, and SiC powder are mixed at a weight ratio of Al: Si: SiC = 1: 1: 8, and this mixed powder is loaded into a carbon crucible and 1300 ° C. A high Al activity diffusion treatment is performed by performing heat treatment under conditions of ˜1350 ° C. in vacuum for 2 to 6 hours.

  As the metal substrate 100, a metal substrate made of pure Nb and a metal substrate made of an Nb—Hf-based alloy (C-103) were used. The nominal composition of the Nb—Hf-based alloy (C-103) is 10 wt% Hf, 1.0 wt% Ti, 0.7 wt% Zr, 0.5 wt% Ta, 0.5 wt% W, The total concentration of oxygen (O), carbon (C), and nitrogen (N) inevitably contained is 0.01 wt% or more and less than 3 wt%.

  In the high-temperature oxidation test described below, a metal substrate 100 made of Nb or Nb—Hf-based alloy on which an alloy film 500 is formed is inserted into an electric furnace maintained at 1200 ° C. to 1400 ° C. After holding for a period of time, it was taken out from the electric furnace into the atmosphere, rapidly cooled, and this operation was repeated, so-called heating / cooling cycle oxidation was performed. Using a scanning electron microscope equipped with an energy dispersive analyzer, the cross-sectional structure of the sample was observed and the concentration of each element was measured.

<Example 1>
Re plating (step (1)) is performed on the surface of the metal substrate 100 made of an Nb metal plate having a purity of 99 atomic% or more, followed by heat treatment at 1500 ° C. in a vacuum for 1 hour. This process was repeated twice. This heat treatment is for ensuring the adhesion between the Nb metal plate and the Re plating layer. Subsequently, a low Si activity diffusion treatment (step (3)) was performed at 1600 ° C. for 4 hours in an Ar gas atmosphere.

The test piece thus prepared was cut and polished, the cross-sectional structure was observed, and the concentration distribution in the thickness direction of each element contained in the test piece was measured using EPMA. FIG. 3 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 4 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 in the photograph shown in FIG. 3) measured using EPMA. Table 1 summarizes the concentration of each element shown in FIG. 4, and Table 2 summarizes the minimum and maximum concentrations of each layer shown in Table 1.

From these results, the alloy film 500 is formed of the transition region 110 including the Nb ₅ Si ₃ phase, the intermediate layer 300 including the Q phase, and the outer layer 400 including the ReSi _1.8 phase from the side of the metal substrate 100 made of the Nb metal plate. It can be seen that a boundary region 299 is formed between the transition region 110 and the intermediate layer 300, and a boundary region 399 is formed between the intermediate layer 300 and the outer layer 400. However, in this test piece subjected to the low Si activity diffusion treatment, the inner layer 200 including the NbSi ₂ phase is not formed.

Due to this fact, as shown in FIG. 1, in the low Si activity diffusion treatment, Re forms ReSi _1.8 whereas NbSi ₂ does not, but forms Nb ₅ Si ₃ phase and Q phase. In addition, it is similarly understood that the Nb ₅ Si ₃ phase 410 exists in the ReSi _1.8 phase of the outer layer 400. As shown in Table 2, the composition of this Q phase is (29.8-40.3) atomic% Si, (38.2-54.5) atomic% Nb, (15.4-21.6) atoms. % Re.

Following the low Si activity diffusion treatment, a high Si activity diffusion treatment (step (4)) was performed at 1350 ° C. for 1 minute in an Ar gas atmosphere. FIG. 5 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 6 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 5) measured using EPMA. Table 3 summarizes the concentration of each element shown in FIG. 6, and Table 4 summarizes the minimum value and maximum value of the concentration of each layer shown in Table 3.
From this result, it is understood that the inner layer 200 is not formed when the high Si activity diffusion treatment time is short (in this case, 1 minute).

Following the high Si activity diffusion treatment for 1 minute, the high Si activity diffusion treatment (step (4)) was performed at 1350 ° C. for 1 hour in an Ar gas atmosphere. FIG. 7 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 8 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 7) measured using EPMA. Table 5 summarizes the concentration of each element shown in FIG. 8, and Table 6 summarizes the minimum value and maximum value of the concentration of each layer shown in Table 5.
These results, the alloy film 500, in order from the metal substrate 100 side, comprising a mixed phase of the inner layer 200, NbSi ₂ phase and Resi _1.8 phase comprising a transition region 110, NbSi ₂ phase containing Nb ₅ Si ₃ phase a layer structure of the intermediate layer 300, Resi outer layer 400 containing _1.8 phase, the boundary region 199 between the transition region 110 and the inner layer 200 is a mixed phase of Nb ₅ Si ₃ phase and NbSi ₂ phases. Note that the NbSi ₂ phase 410 is mixed in the outer layer 400.

<Example 2>
Following the last high Si activity diffusion treatment in Example 1, a high Al activity diffusion treatment (step (5)) was performed in an Ar gas atmosphere at 1350 ° C. for 1 hour. FIG. 9 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 10 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 9) measured using EPMA. Table 7 summarizes the concentration of each element shown in FIG. 10, and Table 8 summarizes the minimum and maximum values of the concentration of each layer shown in Table 7.
These results, the alloy film 500, in order from the metal substrate 100 side, the inner layer 200 comprising a transition region 110, NbSi ₂ phase containing Nb ₅ Si ₃ phase, NbSi ₂ phase and Re (Al, Si) _1.8 phase and The intermediate layer 300 including the mixed phase of the outer layer 400 and the outer layer 400 including the Re (Al, Si) _1.8 phase have a layer structure of the boundary region 199 between the transition region 110 and the inner layer 200, and the Nb ₅ Si ₃ phase and the NbSi ₂ phase. It is a mixed phase with the phase. Further, the concentration distribution of Al is similar to that of Re, and it is characteristic that Al replaces part of Si in the ReSi _1.8 phase to form a Re (Al, Si) _1.8 phase.

<Example 3>
Following the last high Si activity diffusion treatment in Example 1, high Al activity diffusion treatment (step (5)) was performed in vacuum at 900 ° C. for 1 hour, followed by 1300 ° C. for 1 hour. . FIG. 11 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 12 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 in the photograph shown in FIG. 11) measured using EPMA. Table 9 summarizes the concentration of each element shown in FIG. 12, and Table 10 summarizes the minimum value and the maximum value of the concentration of each layer shown in Table 9.
These results are similar to the results of FIG. 9, FIG. 10, Table 7 and Table 8 described above. In particular, the intermediate layer 300 is a mixed phase of NbSi ₂ phase and Re (Al, Si) _1.8 phase. It is clearly recognized that there is.

<Example 4>
An Nb—Hf-based alloy (C-103) was used as the material for the metal substrate 100. Using this metal substrate 100, following the step (1), step (2), step (1), step (3), the high Si activity diffusion treatment of step (4) is performed at 1350 ° C., vacuum, 1 hour. Performed under conditions. FIG. 13 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 14 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 13) measured using EPMA. Table 11 summarizes the concentration of each element shown in FIG. 14, and Table 12 summarizes the minimum and maximum concentrations of each layer shown in Table 11.
From these results, the alloy film 500 has an Nb ₅ Si ₃ phase containing Hf and an intermediate layer 300 containing an NbSi ₂ phase and a ReSi _1.8 phase containing W and Mo in order from the metal substrate 100 side. The outer layer 400 is a ReSi _1.8 phase containing W and Mo, and is divided into a layer 320 and a layer 340 due to the difference in structure. A boundary region 299 exists between the transition region 110 and the intermediate layer 300. The boundary region 299 has a structure in which the NbSi ₂ phase of the inner layer 200 is included and the Nb ₅ Si ₃ phase is mixed. In other words, the inner layer 200 is not observed as a single continuous layer, but has a discontinuous structure mixed with the boundary region 299.

<Example 5>
Following the last high Si activity diffusion treatment in Example 4, a high Al activity diffusion treatment (step (5)) was performed at 1350 ° C. for 4 hours under vacuum conditions. FIG. 15 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 16 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 15) measured using EPMA. Table 13 summarizes the concentration of each element shown in FIG. 16, and Table 14 summarizes the minimum value and the maximum value of the concentration of each layer shown in Table 13.
From these results, in order from the metal substrate 100 side, the transition region 110 is an Nb ₅ Si ₃ phase containing Hf, the inner layer 200 is an NbSi ₂ phase containing Re, and the intermediate layer 300 is NbSi containing W and Mo. _It can be seen that the mixed phase of the _two phases and the Re (Al, Si) _1.8 phase, and the outer layer 400 is the Re (Al, Si) _1.8 phase containing W and Mo. From this, it can be seen that the concentration distribution of Re coincides with that of Al, and Al is dissolved in the Re (Al, Si) _1.8 phase. A boundary region 199 exists between the transition region 110 and the inner layer 200, and a boundary region 399 exists between the intermediate layer 300 and the outer layer 400.

<Example 6>
A plate made of an Nb-17 at% Si alloy (nominal composition) was used as the metal substrate 100. The phases constituting the Nb-17 at% Si alloy are an Nb (Si) solid solution, an Nb ₃ Si phase, and an Nb ₅ Si ₃ phase. Re plating (step (1)) is performed on the surface of the metal substrate 100, followed by heat treatment at 1500 ° C. in vacuum for 2 hours. This heat treatment is to ensure adhesion between the Nb-17 at% Si alloy plate and the Re plating layer. Subsequently, a slurry containing fine powders of W and Mo is applied to the surface of the Re plating layer (step (2)), followed by heat treatment at 1500 ° C. in vacuum for 2 hours. Subsequently, a slurry containing fine powder of Re is applied to the surface of the layer containing W and Mo thus formed (step (2)), followed by heat treatment at 1500 ° C. in vacuum for 2 hours. Do. Subsequently, a low Si activity diffusion treatment (step (3)) was performed at 1650 ° C. for 9 hours in an Ar gas atmosphere. Subsequently, a high Si activity diffusion treatment (step (4)) was performed in vacuum at 1350 ° C. for 13 hours. Finally, high Al activity diffusion treatment (step (5)) was performed in vacuum at 1300 ° C. for 6 hours.

Cutting the test piece that was subjected to the above-described Re plating and subsequent heat treatment, application of slurry containing fine powders of W and Mo, and subsequent heat treatment, and application of slurry containing fine powder of Re and subsequent heat treatment, Polishing and observing the cross-sectional structure, and using EPMA, the concentration distribution in the thickness direction of each element contained in the test piece was measured. FIG. 17 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 18 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 in the photograph shown in FIG. 17) measured using EPMA. Table 15 summarizes the concentration of each element shown in FIG.

From these results, from the metal substrate 100 side made of an Nb-17 at% Si alloy plate, an Nb (Si) phase enriched layer, a plating layer mainly containing Re, and a layer mainly containing W and Mo. It can be seen that a layer mainly composed of Re and Re is formed.

Next, the test piece that had been processed up to the low Si activity diffusion treatment was cut and polished, the cross-sectional structure was observed, and the concentration distribution in the thickness direction of each element contained in the test piece was measured using EPMA. . FIG. 19 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 20 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG2 in the photograph shown in FIG. 19) measured using EPMA. Table 16 summarizes the concentration of each element shown in FIG.

From these results, the alloy film 500 includes the transition region 110 including the Nb ₅ Si ₃ phase, the intermediate layer 300 including the Q phase, and the ReSi _1.8 phase from the metal substrate 100 side made of the Nb-17 at% Si alloy plate. It can be seen that the outer layer 400 has a layer structure. However, in this test piece subjected to the low Si activity diffusion treatment, the inner layer 200 including the NbSi ₂ phase is not formed.

Next, the test piece that had been subjected to the high Al activity diffusion treatment was cut and polished, the cross-sectional structure was observed, and the concentration distribution in the thickness direction of each element contained in the test piece was measured using EPMA. . FIG. 21 shows an optical micrograph of the cross-sectional structure of the test piece. FIG. 22 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 21) measured using EPMA. Table 17 summarizes the concentration of each element shown in FIG.

These results, the alloy film 500, in order from the metal substrate 100 side, the inner layer 200 comprising a transition region 110, NbSi ₂ phase containing Nb ₅ Si ₃ phase, NbSi ₂ phase and Re (Al, Si) _1.8 phase and intermediate layer 300 including the mixed phase, Re (Al, Si) having a layer structure of outer layer 400 containing _1.8 phase, the boundary region 299 between the inner layer 200 and the intermediate layer 300 is NbSi ₂ phase and Re (Al, Si) A mixed phase of _1.8 phase, and a boundary region 399 between the intermediate layer 300 and the outer layer 400 is a mixed phase of NbSi ₂ phase and Re (Al, Si) _1.8 phase. Further, the concentration distribution of Al is similar to that of Re, and it is characteristic that Al replaces part of Si in the ReSi _1.8 phase to form a Re (Al, Si) _1.8 phase.

Next, the results of a high-temperature oxidation experiment on a heat-resistant metal member test piece will be described.
<High-temperature oxidation experiment 1>
By using a Nb metal plate as the metal substrate 100, following the step (1), the step (2), the step (1), and the step (3), the high Si activity diffusion treatment in the step (4) is performed. An alloy film 500 was formed on the Nb metal plate. Then, after hold | maintaining at 1400 degreeC in air | atmosphere for 1 hour, the cyclic oxidation which quenches rapidly to room temperature was implemented 4 times. FIG. 23 shows an optical micrograph of the cross-sectional structure of the test piece after oxidation. FIG. 24 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 in the photograph shown in FIG. 23) measured using EPMA. Table 18 summarizes the concentration of each element shown in FIG. 24, and Table 19 summarizes the minimum and maximum values of the concentration of each layer shown in Table 18.
From these results, from the metal substrate 100 side, the transition region 110 is the Nb ₅ Si ₃ phase, the boundary region 199 is the mixed phase of the porous Nb ₅ Si ₃ phase and the ReSi _1.8 phase, and the boundary region 299 is the ReSi _1.8 phase. The intermediate layer 300 is a mixed phase of WSi ₂ phase containing Re and Mo and a ReSi _1.8 phase, and the outer layer 400 is a ReSi _1.8 phase containing W and Mo. Recognize. The oxide 600 is SiO ₂ . Accordingly, the Si concentration in the ReSi _1.8 phase of the outer layer 400 is reduced by forming SiO ₂ , but Si is supplied from the NbSi ₂ phase of the inner layer 200 to the outer layer 400 to maintain the ReSi _1.8 phase. As a result, the inner layer 200 disappears and forms boundary regions 199 and 299. In particular, it can be seen that the boundary region 199 becomes a porous Nb ₅ Si ₃ phase.

<High-temperature oxidation experiment 2>
An Nb metal plate is used as the metal substrate 100, and the high Al activity diffusion process of the step (5) is performed on the Nb metal plate following the steps (1), (3), and (4). An alloy film 500 was formed. Then, after hold | maintaining at 1300 degreeC in air | atmosphere for 1 hour, the cyclic oxidation which cools rapidly to room temperature was implemented 4 times. FIG. 25 shows an optical micrograph of the cross-sectional structure of the test piece after oxidation. FIG. 26 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 25) measured using EPMA. Table 20 summarizes the concentration of each element shown in FIG. 26, and Table 21 summarizes the minimum and maximum concentrations of each layer shown in Table 20.
From these results, from the metal substrate 100 side, the transition region 110 is an Nb ₅ Si ₃ phase, the inner layer 200 is an NbSi ₂ phase containing Re and Al, and the boundary region 199 is an Nb ₅ Si ₃ phase and an NbSi ₂ phase. The intermediate layer 300 is a mixed phase of NbSi ₂ phase and a Re (Al, Si) _1.8 phase containing Al, and the outer layer 400 is a Re (Al, Si) _1.8 phase containing Al. Recognize. The boundary region 399 includes the same crystal phase as the intermediate layer 300 but has a different structure. The oxide 600 is Al ₂ O ₃ . In the high Al activity diffusion treatment, as shown in an example in Example 2, the outer layer is a Re (Al, Si) _1.8 phase, and the Al concentration is lowered / disappeared by high-temperature oxidation, and changed to a ReSi _1.8 phase. You can see that

<High-temperature oxidation experiment 3>
An Nb metal plate is used as the metal substrate 100, and the high Al activity diffusion process of the step (5) is performed on the Nb metal plate following the steps (1), (3), and (4). An alloy film 500 was formed. Then, after hold | maintaining at 1400 degreeC in air | atmosphere for 1 hour, the cyclic oxidation which cools rapidly to room temperature was implemented once. FIG. 27 shows an optical micrograph of the cross-sectional structure of the test piece after oxidation. FIG. 28 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 in the photograph shown in FIG. 27) measured using EPMA. Table 22 summarizes the concentration of each element shown in FIG. 28, and Table 23 summarizes the minimum and maximum concentrations of each layer shown in Table 22.
From these results, from the metal substrate 100 side, the transition region 110 is an Nb ₅ Si ₃ phase, the inner layer 200 is an NbSi ₂ phase containing Re and Al, and the boundary region 199 is an Nb ₅ Si ₃ phase and an NbSi ₂ phase. It can be seen that the intermediate layer 300 is a mixed phase of an NbSi ₂ phase and a Re (Al, Si) _1.8 phase containing Al, and is porous. The outer layer 400 is a Re (Al, Si) _1.8 phase containing Al. The outer layer 400 includes an NbSi ₂ phase. The oxide 600 is Al ₂ O ₃ . In the high Al activity diffusion treatment, as shown in an example in Example 2, the outer layer is a Re (Al, Si) _1.8 phase, and the Al concentration is lowered / disappeared by high-temperature oxidation, and changed to a ReSi _1.8 phase. You can see that

<High-temperature oxidation experiment 4>
Using the Nb—Hf-based alloy (C-130) as the metal substrate 100, following the step (1), step (2), step (1), step (3), step (4), step (5) An alloy film 500 was formed on the Nb—Hf-based alloy (C-130) by performing a high Al activity diffusion treatment, followed by four-cycle oxidation at 1200 ° C. in the atmosphere. FIG. 29 shows an optical micrograph of the cross-sectional structure of the test piece after oxidation. FIG. 30 shows the measurement results of the concentration distribution of each element (concentration distribution along the line LG1 of the photograph shown in FIG. 29) measured using EPMA. Table 24 summarizes the concentration of each element shown in FIG. 30, and Table 25 summarizes the minimum and maximum values of the concentration of each layer shown in Table 24.
From these results, from the metal substrate 100 side, the transition region 110 is an Nb ₅ Si ₃ phase containing Hf, the inner layer 200 is an NbSi ₂ phase containing Re, and the boundary region 199 is an Nb ₅ Si ₃ phase and an NbSi ₂ phase. The intermediate layer 300 is a mixed phase of an NbSi ₂ phase containing W and Mo and a Re (Al, Si) _1.8 phase, and the outer layer 400 is Re (Al, Si) _1.8 containing W and Mo. It turns out that it is a phase. The oxide 600 is Al ₂ O ₃ . Under the oxidation conditions of 1200 ° C. and 4 cycles, Al remains in the alloy film 500, and the sum of Al and Si corresponds to the Re (Al, Si) _1.8 phase. From this, it can be seen that the concentration distribution of Re coincides with that of Al, and Al is dissolved in the Re (Al, Si) _1.8 phase.

From the above high-temperature oxidation experiments 1 to 4, by forming the alloy film 500 having at least the transition region 110, the inner layer 200, the intermediate layer 300, and the outer layer 400 on the metal substrate 100, protective SiO is formed on the surface of the alloy film 500. forming a _second coating, or in particular, the inner layer 200 NbSi ₂ phases, to form a protective Al ₂ O ₃ film on the surface of the alloy coating 500 by an outer layer 400 and Re (Al, Si) _1.8 phase can further, Si by NbSi ₂ phase of the inner layer 200 is changed to Nb ₅ Si ₃ phase is supplied to the Re (Al, Si) _1.8 phase, Re (Al, Si) _1.8 phase, the more Resi _1.8 phase It was demonstrated that it can be maintained.

As described above, according to the heat-resistant metal member according to this embodiment, the alloy film 500 formed on the surface of the metal substrate 100 made of Nb, Nb—Hf base alloy or Nb—Si base alloy is crystalline. Transition region 110 including Nb ₅ Si ₃ phase as a phase, inner layer 200 including NbSi ₂ phase as a crystal phase, intermediate layer 300, and at least one of ReSi _1.8 phase and Re (Al, Si) _1.8 phase as a crystal phase By including the outer layer 400, even when exposed to a corrosive atmosphere of high-temperature combustion gas, it can exhibit excellent high-temperature oxidation resistance, can also have excellent heat resistance and durability, and has a long life A heat-resistant metal member can be realized. This heat-resistant metal member is suitable for use not only in a combustion chamber of a rocket engine but also in a gas turbine member, for example, a moving blade of a power generation gas turbine. FIG. 31 shows an example in which this heat-resistant metal member is applied to a combustor of a two-liquid rocket engine. As shown in FIG. 31, a cylindrical combustor is constituted by an alloy film 500 formed on the surface of a metal substrate 100. A flange 700 is attached to one end of the combustor. The flange 700 is provided with an introduction hole 701 for introducing an oxidant at the center thereof, and introduction holes 702 and 703 for introducing fuel are provided around the introduction hole 701. In this combustor, the liquid oxidant 704 introduced from the introduction hole 701 and the liquid fuel 705 introduced from the introduction holes 702 and 703 are sprayed into the combustion chamber to cause combustion, and the combustion gas Thrust is obtained by the gas stream being jetted from the nozzle through the throat. Liquid fuel 705 is also injected from the introduction holes 702 and 703 to the inner peripheral surface of the combustion chamber to form a liquid film 800, and the metal substrate 100 is cooled by the liquid film 800. For example, hydrazine (N ₂ H ₄ ) is used as the fuel, and dinitrogen tetroxide (N ₂ O ₄ ) is used as the oxidant. Although the inside of the combustor is exposed to a high-temperature oxidizing atmosphere, as described above, the metal base material 100 having the alloy film 500 formed on the surface is excellent in heat resistance and durability, so that the combustor has a long life. Can be achieved.

  Although one embodiment and example of the present invention have been specifically described above, the present invention is not limited to the above-described embodiment and example, and various types based on the technical idea of the present invention. Deformation is possible.

  Further, the above-described Q phase which is an Nb—Re—Si ternary alloy phase (composition is (29.8 to 40.3) atomic% Si, (38.2 to 54.5) atomic% Nb, (15. Since 4 to 21.6) atomic% Re) has high mechanical strength, it is possible to improve the mechanical strength by forming an alloy film comprising this Q phase on the surface of the metal substrate. As a method for forming the Q phase, for example, a surface of a metal substrate such as an Nb plate is plated with Re as described above, or a slurry containing fine powder of Re is applied, and then a low Si activity is achieved. A method of performing a diffusion treatment or a method of performing a low Si activity diffusion treatment using a mixed powder of Nb powder and Re powder as a vapor source on a metal substrate such as an Nb plate can be used.

  DESCRIPTION OF SYMBOLS 100 ... Metal substrate, 110 ... Transition region, 199 ... Boundary region, 200 ... Inner layer, 299 ... Boundary region, 300 ... Middle layer, 399 ... Boundary region, 400 ... Outer layer, 500 ... Alloy film

Claims (18)

A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an inner layer including an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) A refractory metal member including an outer layer containing at least one of _1.8 phases.   The inner layer has Si of 46.3 atomic% or more and less than 67.5 atomic%, Nb of 26.2 atomic% or more and 35.2 atomic% or less, Re, Al, Mo, W, Ti, Cr, Hf, O, 2. The refractory metal member according to claim 1, comprising at least one element selected from the group consisting of C and N at 10.8 atomic% or less, and the total amount of these elements is 100 atomic% or less.   The outer layer has Si of 33.1 atomic% or more and less than 68.1 atomic%, Al of 37.0 atomic% or less, Re of 6.7 atomic% or more and 41.1 atomic% or less, Nb, Mo, W, Ti 3. The composition according to claim 1, wherein the element contains at least one element selected from the group consisting of Cr, Hf, O, C, and N at 16.3 atomic% or less, and the total amount of these elements is 100 atomic% or less. Heat-resistant metal member.   The heat-resistant metal member according to any one of claims 1 to 3, wherein the outer layer contains 16.3 atomic% or less of Nb. 5. The intermediate layer according to claim 1, wherein the intermediate layer includes an MSi ₂ phase (M is at least two elements selected from the group consisting of Fe, Cr, Al, Mo, W, Re, and Hf) as a crystal phase. The heat-resistant metal member according to one item.   The boundary region according to any one of claims 1 to 5, further comprising a boundary region in at least one of the transition region and the inner layer, between the inner layer and the intermediate layer, and between the intermediate layer and the outer layer. Heat-resistant metal member.   The heat resistant metal member according to any one of claims 1 to 6, wherein the inner layer comprises a continuous layer or a discontinuous layer. Forming a layer containing Re on a metal substrate made of Nb, Nb—Hf-based alloy or Nb—Si-based alloy;
First Si diffusion penetration treatment at a temperature of 1600 ° C. or higher and 1650 ° C. or lower using a mixed powder of Nb ₅ Si ₃ phase powder and NbSi ₂ phase powder as a vapor source on the metal substrate on which the layer containing Re is formed A process of performing
A method for producing a heat-resistant metal member, comprising: performing the second Si diffusion permeation treatment for 10 minutes or more at a temperature of 1300 ° C. or higher and 1350 ° C. or lower after performing the first Si diffusion permeation treatment.   The method for producing a refractory metal member according to claim 8, wherein the layer containing Re is formed by electroplating and / or by applying a slurry in which a fine powder containing at least Re is mixed with an organic binder.   The method for producing a heat-resistant metal member according to claim 8 or 9, wherein the first Si diffusion penetration treatment and the second Si diffusion penetration treatment are performed for 10 minutes to 13 hours.   Step of performing Al diffusion penetration treatment at a temperature of 1300 ° C. or higher and 1350 ° C. or lower using a mixed powder of Al powder, Si powder, and SiC powder as a sintering inhibitor after performing the second Si diffusion penetration treatment. The method for producing a heat-resistant metal member according to any one of claims 8 to 10, further comprising:   The method for producing a refractory metal member according to claim 11, wherein the Al diffusion permeation treatment is performed for 10 minutes to 6 hours. A transition region including a Nb ₅ Si ₃ phase as a crystalline phase and a NbSi ₂ as a crystalline phase, which are formed on the surface of a metal substrate made of Nb, Nb—Hf-based alloy or Nb—Si-based alloy, in that order from the metal substrate side. An alloy film including an inner layer including a phase, an intermediate layer, and an outer layer including at least one of a ReSi _1.8 phase and a Re (Al, Si) _1.8 phase as a crystal phase. Forming a layer containing Re on a metal substrate made of Nb, Nb—Hf-based alloy or Nb—Si-based alloy;
First Si diffusion penetration treatment at a temperature of 1600 ° C. or higher and 1650 ° C. or lower using a mixed powder of Nb ₅ Si ₃ phase powder and NbSi ₂ phase powder as a vapor source on the metal substrate on which the layer containing Re is formed A process of performing
A method for producing an alloy film, comprising: performing the second Si diffusion penetration treatment for 10 minutes or more at a temperature of 1300 ° C. or more and 1350 ° C. or less using the Si powder as a vapor source after the first Si diffusion penetration treatment.   Step of performing Al diffusion penetration treatment at a temperature of 1300 ° C. or higher and 1350 ° C. or lower using a mixed powder of Al powder, Si powder, and SiC powder as a sintering inhibitor after performing the second Si diffusion penetration treatment. The method for producing an alloy film according to claim 14, further comprising: A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an inner layer including an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) A rocket engine including an outer layer including at least one of _1.8 phases. Have at least one rocket engine,
The above rocket engine
A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an inner layer including an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) An artificial satellite including an outer layer including at least one of _1.8 phases. A metal substrate made of Nb, Nb-Hf-based alloy or Nb-Si-based alloy;
Having an alloy film formed on the surface of the metal substrate,
The alloy film includes, in order from the metal substrate side, a transition region including an Nb ₅ Si ₃ phase as a crystal phase, an inner layer including an NbSi ₂ phase as a crystal phase, an intermediate layer, and a ReSi _1.8 phase and Re (Al, Si) A power generation gas turbine having a moving blade including an outer layer including at least one of _1.8 phases.