JP2018162506A - High temperature member and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for forming an oxide barrier layer contributing to a further improvement of durability of a thermal barrier coating (TBC).SOLUTION: A manufacturing method of a high temperature member includes a step for forming a bond coating composed of a NiCoCrAlY alloy by flame spraying a NiCoCrAlY alloy powder on a substrate composed of a heat-resistant alloy, a step for forming an oxide barrier layer on a surface of the bond coating with a preliminary oxidation treatment of the substrate with the bond coating formed under a vacuum environment with an oxygen partial pressure of 1.0×10-1.0×10Pa at 1000-1200°C for 1-6 hours, and a step for forming a top coating on a surface of the oxide barrier layer by flame spraying an oxide-based ceramic powder.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a high-temperature member to which a thermal barrier coating (TBC) is applied and a method for manufacturing the same.

  Traditionally, TBC has been used to protect the components of industrial gas turbines from high temperature environments. A TBC generally has a low thermal conductivity topcoat (heat shielding layer) made of a ceramic having a low thermal conductivity on a metal substrate, and a bond coat for improving adhesion between the topcoat and the substrate ( A bonding layer).

  In recent years, due to increasing awareness of energy problems, gas turbines are required to further improve efficiency. In order to improve the efficiency of the gas turbine, increasing the turbine inlet temperature is one effective means. As the turbine inlet temperature rises, high-temperature members such as nozzles, guide vanes, and blades used in a high-temperature environment are exposed to a higher-temperature environment. The high temperature member of the gas turbine is provided with a heat shielding property that suppresses heat transfer from the surface to the inside by applying TBC to the surface thereof. However, if TBC is used for a long time at a high temperature, the top coat peels off and the heat shielding performance is deteriorated. It has become difficult.

  Various mechanisms for causing peeling of the top coat have been discussed, but an oxide (Thermally Grown Oxide: TGO) formed by high-temperature oxidation of the bond coat is involved at the interface between the top coat and the bond coat. It is recognized that Therefore, in order to suppress the peeling of the TBC topcoat and improve the durability of the TBC, it is considered important to suppress the growth of TGO. In Patent Documents 1, 2, and 3, techniques for suppressing the growth of TGO are proposed.

In Patent Document 1, after a bonding layer made of MCrAlY is provided on the surface of a metal base material, an α-Al ₂ O ₃ layer is formed on the surface of the bonding layer by performing heat treatment at 900 ° C. in a vacuum environment. Subsequently, it is described that a high-temperature member is manufactured by providing a heat-shielding layer made of an oxide-based ceramic on the surface of the α-Al ₂ O ₃ layer. Here, an attempt is made to suppress TGO growth at the interface between the thermal barrier layer and the bonding layer by forming an α-Al ₂ O ₃ layer having a low growth rate on the bonding layer.

Further, in Patent Document 2, MCrAlX (M is one or more selected from Co, Cr, Ni and Fe, and X is one selected from the group consisting of Co, Cr, Ni and Fe on the surface of a heat-resistant alloy base material having an Al content of 3 to 24 mass%, X Is provided with a high-temperature oxidation-resistant alloy film made of Y, Hf, Ta, Cs, Ce, La, Th, W, Si, Pt, Mn and B). Is formed by laminating and forming a chromium oxide film (or a chromium oxide film and a chromium film) via an Al ₂ O ₃ layer. Here, the surface of the high-temperature oxidation-resistant alloy film is positively formed with an oxidation barrier layer made of only Al ₂ O ₃ that is dense, rich in adhesion, and excellent in protective properties. The excellent high temperature oxidation resistance of the alloy film can be fully exhibited.

Moreover, in patent document 3, in the oxidation-resistant coating member which formed the ceramic thermal-insulation layer through the oxidation-resistant film on the surface of the heat-resistant alloy base material, it contains as an impurity element in the interface of an oxidation-resistant film and a ceramic thermal-insulation layer. Forming a thin α-Al ₂ O ₃ layer having a Co and Ni content of 1 atomic% or less. The α-Al ₂ O ₃ layer is composed of columnar crystal grains extending in a direction perpendicular to the surface of the heat-resistant alloy and having a thickness of 0.2 μm or more.

JP 2000-17458 A JP 2004-76099 A JP 2007-262530 A

  In view of the above-described background art, the present invention exhibits an excellent effect in suppressing the growth of interfacial oxides of the TBC topcoat and bond coat, as well as an oxidation barrier layer that contributes to further improving the durability of the TBC. The purpose is to propose a technology to form And the lifetime improvement of the high temperature member to which TBC was applied by the improvement of durability of TBC is aimed at.

As described in Patent Documents 1 to 3, α-Al ₂ O ₃ functions as an oxidation barrier that suppresses the growth of the interface oxide between the top coat and the bond coat. On the other hand, different _θ-Al 2 _{O 3} crystal structure and _α-Al 2 _{O 3} is to include lattice defects, the effect of the oxidation barrier, such as _α-Al 2 _{O 3} can not be expected. Moreover, since the phase transition from θ-Al ₂ O ₃ to α-Al ₂ O ₃ is accompanied by a volume shrinkage of about 13%, if θ-Al ₂ O ₃ is present at the interface between the top coat and the bond coat, There is a possibility of causing a defect in the oxidation barrier layer by phase transition. If defects occur in the oxidation barrier layer, the oxidation barrier effect is impaired, which may cause the topcoat to peel off. From these facts, in order to further improve the durability of TBC, when forming an oxidation barrier layer at the interface between the top coat and the bond coat, α-Al ₂ O ₃ is not generated without generating θ-Al ₂ O _3. It is desirable to produce only ₂ O ₃ .

The inventors of the present application perform a pre-oxidation treatment of the bond coat in a vacuum atmosphere with a low oxygen partial pressure of a certain level or less, thereby hardly generating θ-Al ₂ O ₃ at the interface between the top coat and the bond coat. It was found that an oxidation barrier layer made of α-Al ₂ O ₃ can be generated.

Then, the manufacturing method of the high temperature member which concerns on 1 aspect of this invention is the following.
A step of thermally spraying NiCoCrAlY alloy powder on the surface of a base material made of a heat-resistant alloy to form a bond coat made of NiCoCrAlY alloy;
With respect to the base material on which the bond coat is formed, in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁵ to 1.0 × 10 ⁻⁹ Pa, at a predetermined temperature within a range of 1000 to 1200 ° C. , A step of generating an oxidation barrier layer on the surface of the bond coat by performing a pre-oxidation treatment by heating for 1 to 6 hours;
And a step of thermally spraying an oxide-based ceramic powder on the surface of the oxidation barrier layer to form a top coat.

Moreover, the manufacturing method of the high temperature member which concerns on another one aspect | mode of this invention,
A step of thermally spraying NiCoCrAlY alloy powder on the surface of a base material made of a heat-resistant alloy to form a bond coat made of NiCoCrAlY alloy;
A step of thermally spraying an oxide-based ceramic powder on the surface of the base material on which the bond coat is formed to form a top coat;
Within a range of 1000 to 1200 ° C. in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁵ to 1.0 × 10 ⁻⁹ Pa with respect to the base material coated with the bond coat and the top coat. And a step of generating an oxidation barrier layer at the interface between the bond coat and the top coat by performing a pre-oxidation treatment by heating at a predetermined temperature for 1-6 hours.

The high temperature member according to one embodiment of the present invention is
A base material made of a heat-resistant alloy;
A bond coat made of NiCoCrAlY alloy provided on the surface of the substrate;
An oxidation barrier layer made of α-Al ₂ O ₃ having an equiaxed crystal structure provided on the surface of the bond coat;
And a top coat made of an oxide-based ceramic provided on the surface of the oxidation barrier layer.

  In the method for manufacturing a high temperature member, a temperature increase rate of the bond coat in the preliminary oxidation treatment may be 5-15 ° C./min.

  In the high temperature member and the manufacturing method thereof, the NiCoCrAlY alloy is expressed by mass fraction, 18.0-28.0% Co, 13.0-21.0% Cr, 10.0- It is preferable to contain 15.0% Al and 0.1-0.8% Y.

According to the high temperature member and the manufacturing method thereof, the oxidation barrier layer provided at the interface between the bond coat and the top coat forming the TBC hardly contains θ-Al ₂ O ₃ , and α-Al ₂ consisting of O _3. Therefore, the oxidation barrier layer formed on the high temperature member exhibits an excellent effect in suppressing the growth of the interface oxide of the TBC topcoat and bond coat, and hardly contains θ-Al ₂ O _3. This can contribute to further improvement of the durability of TBC. And the lifetime improvement of the high temperature member to which TBC was applied is realizable by the improvement of durability of TBC.

  ADVANTAGE OF THE INVENTION According to this invention, the high temperature member to which the technique which forms the oxidation barrier layer which contributes to the further improvement of durability of TBC, and the technique can be provided can be provided.

FIG. 1 shows the analysis result of the surface of the bond coat by in-situ XRD when the sample was heated to 1100 ° C. in an air atmosphere. FIG. 2 shows the analysis result of the surface of the bond coat by in-situ XRD when the sample was heated to 1000 ° C. in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹ Pa. FIG. 3 shows the analysis result of the surface of the bond coat by in-situ XRD when the sample was heated to 1000 ° C. in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹² Pa. FIG. 4 is a TEM image of a cross section of a sample that was pre-oxidized in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁴ Pa. FIG. 5 is a TEM image of a cross section of a sample that was pre-oxidized in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁶ Pa. FIG. 6 shows the results of analysis of the surface of the bond coat by XRD of samples pre-oxidized in a vacuum atmosphere and a plurality of air atmospheres having different oxygen partial pressures. FIG. 7 is a chart showing the results of the high temperature oxidation test. FIG. 8 (a) is a cross-sectional SEM photograph of the interface between the bond coat and the top coat after the test piece is exposed to heat for 3000 hours, and FIG. 8 (b) is the bond coat after the comparative test piece is exposed to heat for 3000 hours. It is a cross-sectional SEM photograph of the interface of a topcoat. FIG. 9 is a chart showing the results of a high-temperature oxidation test of a sample subjected to a pre-oxidation treatment after topcoat construction.

(High temperature member)
The high temperature member according to an embodiment of the present invention is obtained by coating a base material made of an alloy having excellent heat resistance with a thermal barrier coating (TBC). TBC is a bond coat (bonding layer) formed on the surface of a substrate, an oxidation barrier layer made of an interface oxide formed on the surface of the bond coat, and a top of low thermal conductivity formed on the surface of the oxidation barrier layer. It consists of a coat (heat shield layer).

The base material is made of a heat-resistant alloy that is generally used as a constituent material of a gas turbine blade or a combustor, such as a Ni-based alloy or a Co-based alloy. Such a heat-resistant alloy is not particularly limited, and examples thereof include heat-resistant alloys such as MAR-M-247 (registered trademark), Udimet520 ^™ , and CMSX-4 (registered trademark).

  The top coat is made of ceramic with low thermal conductivity. Examples of such a low thermal conductivity ceramic include oxide ceramics such as yttria stabilized zirconia (YSZ).

The oxidation barrier layer is mainly composed of α-Al ₂ O ₃ having an equiaxed crystal structure. α-Al ₂ O ₃ is dense and has a slow growth rate due to long-time use in a high-temperature environment. The existence of such an oxidation barrier layer at the interface between the bond coat and the top coat suppresses further growth of the interface oxide between the bond coat and the top coat.

  The bond coat is made of a NiCoCrAlY alloy. The NiCoCrAlY alloy includes a NiCoCrAlYSiHf alloy. In the NiCoCrAlY alloy, the mass fraction of each component has a relationship of Ni> Co> Cr> Al.

In JIS H8260 “Sprayed powder material”, the types of NiCoCrAlY alloy powders are classified by code number 4.3-4.4 (symbol NiCoCrAlY47 22 17 13) and code number 4.5 (symbol NiCoCrAlYSiHf47 22 17 13). As a material for the bond coat, a NiCoCrAlY alloy of the type classified into the code numbers 4.3 to 4.5 may be used. Further, as a material for the bond coat, for example, a commercially available NiCoCrAlY alloy such as AMPERIT (registered trademark) 405, AMPERIT 410, Amdry ^™ 365, Amdry 386 may be used. Table 1 shows chemical components of commercially available NiCoCrAlY alloys.

  The mass fraction of each component of the alloys classified as NiCoCrAlY alloys is Co: 18.0-28.0%, Cr: 13.0-21.0%, Al: 10.0-15.0%, Y : 0.1-0.8%, balance Ni. Moreover, the mass fraction of each component of the alloy classified into NiCoCrAlY alloys (including NiCoCrAlYSiHf alloys) is Co: 18.0-26.0%, Cr: 13.0-21.0%, Al: 10. 0-15.0%, Y: 0.1-1.0%, Hf: 0.1-1.0%, Si :: 0.1-0.7%, and the balance Ni. In addition, the said NiCoCrAlY alloy may contain the trace amount impurity which does not appear in the mass fraction of each component.

It is considered that the mass fraction of each of Ni, Cr, Al, and Co among the components of the NiCoCrAlY alloy is involved in the formation of α-Al ₂ O ₃ . Specifically, among the components of the NiCoCrAlY alloy, an increase in the mass fraction of Cr and Al promotes the formation of α-Al ₂ O ₃ , and an increase in the mass fraction of Ni and Co is the increase in α-Al ₂ O ₃ . It is thought to inhibit production.

  From this, the NiCoCrAlY alloy that can be adopted as the material for the bond coat of the high-temperature member can be defined by the balance of the mass fraction of each component of Ni, Cr, Al, and Co. That is, the NiCoCrAlY alloy suitable as a material for the bond coat is expressed by mass fraction, 18.0-28.0% Co, 13.0-21.0% Cr, 10.0-15.0%. It is preferable to contain Al and 0.1 to 0.8% of Y.

[Method for producing high temperature member]
The high temperature member is manufactured by the following steps (1) to (3). In addition, the manufacturing process of a high temperature member advances in order of (1)-(3).

(1) A NiCoCrAlY alloy is sprayed on the surface of the substrate to form, for example, a bond coat (ie, NiCoCrAlY alloy film) having a thickness of 100 to 150 μm. At this time, for the thermal spraying of the NiCoCrAlY alloy, an HVOF (High Velocity Oxy-Fuel) thermal spraying method called a high-speed flame spraying method or a low pressure plasma spraying (LPPS) is used. The thickness of the bond coat is not limited to the above.

(2) A pre-oxidation treatment of the bond coat formed as described above is performed to generate an oxidation barrier layer (that is, an oxide film) on the surface of the bond coat. In the pre-oxidation treatment, the base material on which the bond coat is formed is within a range of 1000 to 1200 ° C. in a vacuum atmosphere having an oxygen partial pressure of 1.0 × 10 ⁻¹⁵ to 1.0 × 10 ⁻⁹ Pa on average. Heat in a furnace at a given temperature for 1-6 hours. In addition, the time for the heat treatment of the base material is added to the heating time of the preliminary oxidation treatment.

  In the preliminary oxidation treatment, the temperature and environment in the furnace are adjusted so that the rate of temperature rise until the temperature of the bond coat is raised to a predetermined temperature within the range of 1000 to 1200 ° C. is 5-15 ° C./min. In the pre-oxidation treatment, in addition to the oxygen partial pressure and the heating temperature condition, the temperature increase rate of the bond coat affects the crystal structure (an equiaxed crystal structure described later) of the oxidation barrier layer generated on the surface of the bond coat. Conceivable.

  Further, the extremely low oxygen partial pressure in the furnace environment as described above for the pre-oxidation treatment can be realized by evacuating the inside of the furnace with a vacuum pump and introducing argon gas. Here, “vacuum” means a state of a space filled with a pressure lower than atmospheric pressure.

(3) An oxide ceramic with low thermal conductivity is sprayed on the surface of the oxidation barrier layer formed as described above to form a top coat (that is, a ceramic film) having a thickness of about 200 μm. At this time, atmospheric plasma spraying (APS) spraying is used for spraying the low thermal conductive ceramic. The thickness of the top coat is appropriately adjusted according to the use of the high temperature member.

[Analysis of oxidation behavior of bond coat surface]
In order to analyze the oxidation behavior of the bond coat surface during the manufacturing process of high temperature components, the phase composition analysis by in-situ XRD (X-ray diffraction method) is performed on the oxide formed on the bond coat surface Qualitative / qualitative analysis, quantitative analysis, crystal structure solution, etc.).

  The sample for in-situ XRD analysis was formed by spraying NiCoCrAlY alloy powder onto a heat-resistant alloy substrate made of CMSX-4, a single crystal Ni-based alloy, to form a bond coat (ie, NiCoCrAlY alloy film) with a thickness of about 100 μm. The surface of the bond coat is polished until it becomes a mirror surface. This sample was heated at a rate of 10 ° C./min to 1000-1100 ° C., held for 1 hour, and cooled to room temperature at a rate of 50 ° C./min. went. In this preliminary oxidation treatment, the sample was placed on a high-temperature stage (DHS1100 manufactured by Anton Paar) that can control the atmosphere. In order to compare the influence of the oxygen partial pressure, the atmosphere of the high temperature stage was set to a plurality of types of vacuum atmospheres having different degrees of vacuum and an air atmosphere.

  During the preliminary oxidation treatment of the sample for in-situ XRD analysis, the phase composition analysis of the surface oxide of the bond coat by XRD was continuously performed.

FIG. 1 shows the analysis result of the surface of the bond coat by in-situ XRD when the sample was heated to 1100 ° C. in an air atmosphere. According to the analysis result shown in FIG. 1, generation of oxide on the surface of the bond coat was not confirmed until the sample temperature reached 1000 ° C. after heating was started. From around 600 ° C., the peak width of γ-Ni decreased and the peak of β-NiAl appeared. This is because the γ-Ni structure of the sprayed film having low crystallinity progresses with recrystallization. In addition, it is considered that the mixed structure of γ-Ni and β-NiAl which is thermodynamically stable is changed. From the time when the sample temperature exceeded 1000 ° C., the β-NiAl peak disappeared, and instead a θ-Al ₂ O ₃ peak and a weak α-Al ₂ O ₃ peak were detected.

2 and 3 show the results of analysis of the surface of the bond coat by in-situ XRD when the sample was heated to 1000 ° C. in two different oxygen partial pressure vacuum atmospheres. Of the two different oxygen partial pressure conditions, the oxygen partial pressure of condition (a) is 1.0 × 10 ⁻¹ Pa on average, and the oxygen partial pressure of condition (b) is 1.0 × 10 ^{− 12} Pa. FIG. 2 shows the analysis result under the condition (a), and FIG. 3 shows the analysis result under the condition (b).

The analysis results shown in FIG. 2 and FIG. 3 confirm that oxide formation is generated on the surface of the bond coat from the start of heating until the sample temperature reaches 1000 ° C. under any oxygen partial pressure conditions described above. Was not. Under the condition (a), with the start of temperature holding at 1000 ° C., the β-NiAl peak disappeared and an oxide peak appeared instead. The oxides were θ-Al ₂ O ₃ and α-Al ₂ O ₃ , and both appeared at the same time, and the peak intensities of both increased with time. On the other hand, under the condition (b), an oxide peak appeared while maintaining the temperature at 1000 ° C., and this oxide was only α-Al ₂ O ₃ .

According to the above analysis results, the phase transition from θ-Al ₂ O ₃ to α-Al ₂ O ₃ does not proceed sufficiently on the surface of the bond coat in the pre-oxidation treatment at 1100 ° C. for 1 hour in the air atmosphere. It is guessed. On the other hand, in the preliminary oxidation treatment in a vacuum atmosphere with a low oxygen partial pressure, α-Al ₂ O ₃ was generated on the surface of the bond coat even at a lower temperature of 1000 ° C. In particular, in the pre-oxidation treatment in a vacuum atmosphere with a very low oxygen partial pressure under the condition (b), only α-Al ₂ O ₃ was generated without generating θ-Al ₂ O _{3 on} the surface of the bond coat. .

In other words, from the above analysis results, by performing the pre-oxidation treatment of the bond coat in a vacuum atmosphere with a low oxygen partial pressure below a certain level, θ-Al ₂ O ₃ is almost generated at the interface between the top coat and the bond coat. As a result, it was found that α-Al ₂ O ₃ can be produced (without undergoing a phase transition).

[Observation of oxidation barrier layer morphology]
Using a transmission electron microscope (TEM), the form of the oxide (that is, the oxidation barrier layer) generated on the surface of the bond coat was observed.

A sample for TEM observation was obtained by spraying NiCoCrAlY alloy powder onto a heat-resistant alloy substrate made of single crystal Ni-based alloy CMSX-4 to form a bond coat (NiCoCrAlY alloy film) having a thickness of about 100 μm. The surface is polished until it becomes a mirror surface. This sample was pre-oxidized at 1080 ° C. for 4 hours to form an oxidation barrier layer (that is, an oxide film) on the surface of the bond coat. The oxygen partial pressure (average value) of the atmosphere during the pre-oxidation treatment is 1.0 × 10 ⁻³ Pa, 1.0 × 10 ⁻⁹ Pa, 1.0 × 10 ⁻¹⁴ Pa, 1.0 × 10 ^−15. The effect of the partial pressure of oxygen on the formation of the oxidation barrier layer was compared by changing the pressure at different types of Pa and 1.0 × 10 ⁻¹⁶ Pa.

  The sample for TEM observation after the pre-oxidation treatment is subjected to TEM sample preparation processing with a focused ion beam (FIB) to prepare a cross-sectional sample in which a cross section of a predetermined portion of the sample is exposed. The oxidation barrier layer of the cross-sectional sample was observed using TEM. In addition, the phase composition analysis of the oxidation barrier layer by XRD was performed on the sample for TEM observation after the preliminary oxidation treatment.

FIG. 4 is a TEM image of a cross section of a sample that was pre-oxidized in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁴ Pa. In the TEM image of the cross section of the sample in FIG. 4, a continuous oxide film (that is, an oxidation barrier layer) is generated on the surface of the bond coat. Further, from the TEM image of this cross section, the thickness of the oxide film is 0.1-0.5 μm, and the oxide film has an equiaxed crystal having a crystal diameter of about 0.1-0.5 μm. It can be seen that there is almost no side-by-side organization structure. It is considered that the diffusion of substances oxide barrier layer is predominantly grain boundary diffusion, thus, oxidation barrier layer consisting of α-Al ₂ O ₃ of equiaxed organization, the columnar crystal structure alpha-Al ₂ Compared with the oxidation barrier layer made of O ₃ , when the layer thickness is the same, the ratio of the grain boundary surface area in which O and Al diffuse at the interface between the top coat and the bond coat is small, and thus a high oxidation barrier effect. Can be obtained.

FIG. 5 is a TEM image of a cross section of a sample that was pre-oxidized in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁶ Pa. In the TEM image of the cross section of the sample in FIG. 5, oxide is generated on a part of the surface of the bond coat.

In the following Table 2, the oxygen partial pressure in the vacuum atmosphere during the pre-oxidation treatment is 1.0 × 10 ⁻³ Pa, 1.0 × 10 ⁻⁹ Pa, 1.0 × 10 ⁻¹⁴ Pa, 1.0 × 10 ^{−. It} shows the success or failure of the generation of the oxidation barrier layer when it is changed in plural types of ¹⁵ Pa and 1.0 × 10 ⁻¹⁶ Pa.

When the oxygen partial pressure was 1.0 × 10 ⁻¹⁶ Pa, an oxide was produced, but it was not continuous in the form of a film on the bond coat surface, that is, no film was formed. When the oxygen partial pressure was 1.0 × 10 ⁻³ Pa, a composite oxide that was not α-Al ₂ O ₃ and did not have an oxidation barrier function was produced. Formation of an oxidation barrier layer was confirmed when the oxygen partial pressure was in the range of 1.0 × 10 ⁻¹⁵ Pa to 1.0 × 10 ⁻⁹ Pa. From the above, it can be seen that the oxygen partial pressure (pO ₂ ) in the pre-oxidation treatment is preferably 1.0 × 10 ⁻¹⁵ Pa or more and 1.0 × 10 ⁻⁹ Pa or less.

FIG. 6 shows the results of analysis of the surface of the bond coat by XRD of samples pre-oxidized in a vacuum atmosphere and a plurality of air atmospheres having different oxygen partial pressures. In the chart of FIG. 6, Sample-A is a sample preliminarily oxidized in an air atmosphere, Sample-B is a sample preliminarily oxidized in a vacuum atmosphere having an oxygen partial pressure of 1.0 × 10 ⁻¹⁴ Pa, Sample -C shows the analysis result of the sample preliminarily oxidized in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁶ Pa.

In the analysis result of Sample-A, α-Al ₂ O ₃ , θ-Al ₂ O ₃ , and (Ni, Co) Al ₂ O ₄ which is a spinel oxide are detected as oxides on the surface of the bond coat. It was. Moreover, in the analysis results of Sample-B and Sample-C, α-Al ₂ O ₃ is detected as an oxide on the surface of the bond coat, and θ-Al ₂ O ₃ and (Ni, Co) Al ₂ O ₄ are detected. Was not.

From the above analysis results, in Sample-A, α-Al ₂ O ₃ that was not detected in the in-situ XRD analysis results was detected. Therefore, during heat treatment for 4 hours, θ-Al ₂ O ₃ was detected. It is thought that a phase transition from α to α-Al ₂ O ₃ occurred. In addition, it is considered that Ni and Co were oxidized due to the treatment at a high oxygen partial pressure, resulting in (Ni, Co) Al ₂ O ₄ . Ni and Co are said to have an effect of suppressing the phase transition from metastable alumina to α-Al ₂ O ₃ , and cause that θ-Al ₂ O ₃ remains on the surface of the bond coat of Sample-A. It is thought that it became.

On the other hand, in Sample-B and Sample-C, it is considered that only α-Al ₂ O ₃ was detected because the oxygen partial pressure in the pre-oxidation treatment was not a condition for oxidizing Ni and Co. The fact that θ-Al ₂ O ₃ was not detected in Sample-B and Sample-C is consistent with the above-described in-situ XRD analysis results.

From the above, in a relatively high oxygen partial pressure environment, the oxidation products of the NiCoCrAlY alloy include not only α-Al ₂ O ₃ but also metastable alumina such as θ-Al ₂ O ₃ and (Ni, Co) Al ₂ O. Although resulting in _4, when a constant following the oxygen partial pressure, as the oxidation product of NiCoCrAlY alloy clear that it is possible to form only the _α-Al 2 _{O 3} without causing almost _θ-Al 2 _{O 3} became. From this, by performing a pre-oxidation treatment of the bond coat in an appropriate oxygen partial pressure range, an oxidation barrier layer made of α-Al ₂ O ₃ effective for suppressing the growth of the interface oxide is formed on the surface of the bond coat. It can be formed.

[Evaluation of TBC peeling resistance]
In order to evaluate the TBC peel resistance of the high temperature member, an isothermal oxidation test was performed.

  In the high temperature oxidation test, a test piece (and a test piece for comparison) was exposed to heat in the atmosphere using an atmospheric furnace at 1050 ° C. And the test piece was taken out and cut | disconnected in the middle of the high temperature oxidation test, the thickness of the interface oxide of a bond coat and a topcoat was measured by observing the cross section of a test piece in SEM, and image-analyzing.

The test piece for the high temperature oxidation test was formed by spraying NiCoCrAlY alloy powder onto a base material made of a Ni-based alloy (MAR-M-247) to form a bond coat having a thickness of about 150 μm, and an oxygen partial pressure of 1.0 ×. A pre-oxidation treatment is performed at 1080 ° C. for 4 hours in a vacuum atmosphere of 10 ⁻¹⁴ Pa to form an oxidation barrier layer on the surface of the bond coat, and yttria-stabilized zirconia powder is sprayed on the surface of the oxidation barrier layer to about 200 μm. A thick top coat is formed.

A comparative test piece for a high temperature oxidation test was formed by spraying a NiCoCrAlY alloy powder on a base material made of a Ni-based alloy (MAR-M-247) to form a bond coat having a thickness of about 150 μm, and forming a yttria on the surface of the bond coat. A stabilized zirconia powder is sprayed to form a top coat having a thickness of about 200 μm. After the top coat is formed, heat treatment is performed at 1080 ° C. for 4 hours in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁶ Pa. It is what I did. That is, the comparative test piece is different from the test piece in that the pre-oxidation treatment is not performed, the heat treatment is performed after the top coat is formed, and the oxygen partial pressure during the heat treatment. In addition, it has been found that, in the heat treatment (preliminary oxidation treatment) in a vacuum atmosphere having an oxygen partial pressure of 1.0 × 10 ⁻¹⁶ Pa, an oxidation barrier layer is not formed at the interface between the bond coat and the top coat as described above. .

  FIG. 7 is a chart showing the results of the high-temperature oxidation test, where the horizontal axis represents the heat exposure time, and the vertical axis represents the thickness of the interface oxide. According to the results of the high temperature oxidation test shown in FIG. 7, the thickness of the interface oxide is about 20 μm even after 3000 hours of thermal exposure in the test piece, whereas the interfacial oxide after 3000 hours of thermal exposure in the comparative test piece. The thickness is about 35 μm.

  FIG. 8 (a) is a cross-sectional SEM photograph of the interface between the bond coat and the top coat after the test piece is exposed to heat for 3000 hours, and FIG. 8 (b) is the bond coat after the comparative test piece is exposed to heat for 3000 hours. It is a cross-sectional SEM photograph of the interface of a topcoat. From FIG. 8A and FIG. 8B, the test piece subjected to the pre-oxidation treatment is significantly suppressed in the growth of the interface oxide compared to the comparative test piece not subjected to the pre-oxidation treatment. It can be confirmed.

  From the above, it has been clarified that the growth of the interface oxide was effectively suppressed by the oxidation barrier layer generated at the interface between the bond coat and the top coat by the preliminary oxidation treatment of the bond coat.

  In the high temperature material manufacturing method of the above embodiment, the pre-oxidation treatment of the bond coat is performed before the top coat is formed. On the other hand, it was found that a similar high-temperature member can be produced even if the bond coat is pre-oxidized after the top coat is formed.

  That is, said high temperature member can be manufactured also with the manufacturing method which concerns on the modification 1 which consists of following process (1)-(3). In addition, a process progresses in order of (1)-(3).

(1) A NiCoCrAlY alloy powder is sprayed on the surface of a base material made of a heat-resistant alloy to form a bond coat made of a NiCoCrAlY alloy.
(2) An oxide ceramic powder is sprayed on the surface of the substrate on which the bond coat is formed to form a top coat. (3) With respect to the substrate coated with the bond coat and the top coat, within a range of 1000 to 1200 ° C. in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁵ to 1.0 × 10 ⁻⁹ Pa. An oxidation barrier layer is formed at the interface between the bond coat and the top coat by performing a pre-oxidation treatment by heating at a predetermined temperature of 1 to 6 hours.

  Next, in order to evaluate the properties of the high-temperature member manufactured by the manufacturing method according to Modification 1, a high-temperature oxidation test described below was performed.

A test piece for high-temperature oxidation test was formed by spraying NiCoCrAlY alloy powder to a base material made of a Ni-based alloy (CMSX-4) to form a bond coat having a thickness of about 150 μm, and yttria-stabilized zirconia on the surface of the oxidation barrier layer. After spraying the powder to form a top coat having a thickness of about 200 μm, a pre-oxidation treatment was performed at 1080 ° C. for 4 hours in a vacuum atmosphere having an oxygen partial pressure of 1.0 × 10 ⁻¹⁴ Pa, An oxidation barrier layer is formed at the interface of the top coat.

A comparative test piece for high-temperature oxidation test was formed by spraying NiCoCrAlY alloy powder onto a base material made of Ni-based alloy (CMSX-4) to form a bond coat of about 150 μm thickness, and stabilizing yttria on the surface of the bond coat A zirconia powder was sprayed to form a top coat having a thickness of about 200 μm, and then a heat treatment was performed at 1080 ° C. for 4 hours in a vacuum atmosphere having an oxygen partial pressure of 1.0 × 10 ⁻¹⁶ Pa. It has been found that in the pre-oxidation treatment in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁶ Pa, an oxidation barrier layer is not formed at the interface between the bond coat and the top coat as described above.

  FIG. 9 is a chart showing the results of the high-temperature oxidation test, in which the horizontal axis represents the heat exposure time, and the vertical axis represents the thickness of the interface oxide. The results of the high temperature oxidation test shown in FIG. 9 show that the thickness of the interface oxide is about 8 μm even after the test piece is exposed to heat for 800 hours, whereas the comparative test piece shows the interface oxide after the heat exposure for 800 hours. The thickness was about 19 μm. From the result of this high-temperature oxidation test, even in the high-temperature material manufactured by the manufacturing method according to Modification 1, the growth of the interface oxide is effectively suppressed by the oxidation barrier layer generated at the interface between the bond coat and the top coat. I understand that.

  The high-temperature material and the manufacturing method thereof according to the present invention can be widely applied to high-temperature members that are exposed to high-temperature environments such as boilers and jet engine components, as well as industrial gas turbine components.

Claims (6)

A step of thermally spraying NiCoCrAlY alloy powder on the surface of a base material made of a heat-resistant alloy to form a bond coat made of NiCoCrAlY alloy;
With respect to the base material on which the bond coat is formed, in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁵ to 1.0 × 10 ⁻⁹ Pa, at a predetermined temperature within a range of 1000 to 1200 ° C. , A step of generating an oxidation barrier layer on the surface of the bond coat by performing a pre-oxidation treatment by heating for 1 to 6 hours;
Spraying an oxide-based ceramic powder on the surface of the oxidation barrier layer to form a top coat,
Manufacturing method of high temperature member. A step of thermally spraying NiCoCrAlY alloy powder on the surface of a base material made of a heat-resistant alloy to form a bond coat made of NiCoCrAlY alloy;
A step of thermally spraying an oxide-based ceramic powder on the surface of the base material on which the bond coat is formed to form a top coat;
Within a range of 1000 to 1200 ° C. in a vacuum atmosphere with an oxygen partial pressure of 1.0 × 10 ⁻¹⁵ to 1.0 × 10 ⁻⁹ Pa with respect to the base material coated with the bond coat and the top coat. A step of generating an oxidation barrier layer at the interface between the bond coat and the top coat by performing a pre-oxidation treatment by heating at a predetermined temperature for 1-6 hours,
Manufacturing method of high temperature member. In the preliminary oxidation treatment, the rate of temperature rise until the temperature of the bond coat is raised to the predetermined temperature is 5-15 ° C./min.
The manufacturing method of the high temperature member of Claim 1 or Claim 2. The NiCoCrAlY alloy has a mass fraction of 18.0-28.0% Co, 13.0-21.0% Cr, 10.0-15.0% Al, and 0.1% Comprising -0.8% Y,
The manufacturing method of the high temperature member as described in any one of Claims 1-3. A base material made of a heat-resistant alloy;
A bond coat made of NiCoCrAlY alloy provided on the surface of the substrate;
An oxidation barrier layer made of α-Al ₂ O ₃ having an equiaxed crystal structure provided on the surface of the bond coat;
A top coat made of an oxide-based ceramic provided on the surface of the oxidation barrier layer,
High temperature member. The NiCoCrAlY alloy has a mass fraction of 18.0-28.0% Co, 13.0-21.0% Cr, 10.0-15.0% Al, and 0.1% Comprising -0.8% Y,
The high temperature member according to claim 5.