JP3315246B2 - Metal coating material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal coating material suitable for a material requiring durability and reliability under high temperature and high stress, such as a component material for a moving / static blade of a gas turbine. .

[0002]

2. Description of the Related Art In recent years, the efficiency of energy equipment represented by gas turbines has been rapidly increased. The most important method for achieving such high efficiency is to raise the operating temperature of the equipment, but the material properties required for the constituent materials of the equipment are becoming more severe. As material properties required for high-temperature equipment materials, high-temperature strength, corrosion resistance, oxidation resistance, etc. are important, but in the case of conventional heat-resistant alloys such as iron-based alloys, nickel-based alloys, and cobalt-based alloys, as described above, It is difficult to satisfy various characteristics at the same time.

[0003] Therefore, a corrosion-resistant and oxidation-resistant coating on a heat-resistant alloy as described above has been developed, and at present, the effect is exerted even on an actual machine, which is an indispensable technique for increasing the efficiency of high-temperature equipment. As a material of such a corrosion-resistant and oxidation-resistant coating, an M-Cr-Al-Y alloy (where M is at least one selected from iron, nickel and cobalt)
(Indicating the type of element) is commonly used. M-Cr-Al
The -Y alloy contains a corrosion-resistant element such as Cr or Al, which forms a dense oxide film on the surface, more than the base alloy in order to enhance the corrosion and oxidation resistance effects.

However, even in the case of the M-Cr-Al-Y alloy, interdiffusion occurs due to a difference in element concentration between the base material and the coating layer when used for a long time, causing various problems. That is, since the composition between the base material and the coating layer is significantly different, for example, the diffusion of the coating element into the base material alloy occurs, and a rapid reduction in the strength of the base material alloy is prevented by the embrittlement phase generation reaction accompanying this diffusion. There is a problem that can not be.

[0005] Further, since Al is also a main constituent element of the γ 'phase which is a strengthening phase of the Ni-based alloy, Al
Transformation of the γ 'phase due to the diffusion of Al directly affects the high-temperature strength of the Ni-based alloy.

[0006] In addition, against the depletion of corrosion-resistant elements caused by the interdiffusion between the base material and the coating layer and the surface oxidation as described above, the M-Cr-Al-Y coating layer is enriched with Al by an aluminum pack method or the like. Forming layers has also been performed. However, when an Al-enriched layer is formed by an aluminum pack method or the like on a conventional coating layer of an M-Cr-Al-Y alloy containing a relatively large amount of corrosion-resistant and oxidation-resistant elements such as Al, the Al-enriched layer is During the formation and use of the oxide layer, the formation of an intermetallic compound mainly composed of Al in the coating layer is remarkable, and there is a disadvantage that pores are easily formed inside the coating layer due to an unbalanced element balance. The formation of defects such as pores causes a decrease in high-temperature strength and peeling of the coating.

[0007]

As described above, in a conventional metal coating material in which an M-Cr-Al-Y coating is applied to a heat-resistant alloy, the interdiffusion between the base material and the coating layer, in particular, from the coating layer. There is a problem that the high-temperature strength of the base alloy is apt to decrease due to the diffusion of Al into the material alloy. In addition, to compensate for the depletion of corrosion-resistant elements caused by interdiffusion between the substrate and the coating layer and surface oxidation,
When an Al-enriched layer is formed on a conventional M-Cr-Al-Y coating layer, significant formation of Al-based intermetallic compounds in the coating layer causes defects such as pores inside the coating layer. Is formed, and there is a problem that the material properties are deteriorated.

The present invention has been made to address such a problem, and when a coating layer made of an M-Cr-Al-Y alloy is formed on a substrate, the diffusion between the substrate and the coating layer is reduced. An object of the present invention is to provide a metal coating material capable of suppressing a reaction, maintaining high-temperature strength for a long time, and imparting excellent corrosion resistance and oxidation resistance. In addition, when forming an Al-enriched layer on a coating layer composed of an M-Cr-Al-Y alloy, the above high-temperature strength and corrosion / oxidation resistance are obtained, and the formation of pores inside the coating layer is suppressed. It is another object of the present invention to provide a metal coating material capable of maintaining the excellent material properties.

[0009]

The first metal coating material according to the present invention comprises a base made of an alloy containing at least one selected from the group consisting of Fe, Ni and Co; Coated M-Cr-Al-Y alloy layer (where M is at least one selected from Fe, Ni and Co
Wherein the Al concentration in the M-Cr-Al-Y alloy layer is within ± 0.5% by weight of the Al concentration in the matrix of the base material. It is characterized by having.

Further, the second metal coating material is F
e, a substrate made of an alloy containing at least one selected from Ni and Co as a main component, and an M-Cr-Al-Y alloy layer formed on the surface of the substrate (where M is Fe, Ni and And at least one element selected from Co)
An Al-enriched layer formed on the Al-Y alloy layer and containing a higher concentration of Al than the M-Cr-Al-Y alloy, wherein the M-Cr-Al-Y alloy layer Al concentration in the
It is characterized in that it is within a range of ± 0.5% by weight of the Al concentration in the matrix of the base material.

The base material in the first and second metal coating materials of the present invention may be any one made of an alloy containing at least one of Fe, Ni and Co as a main component. A heat-resistant alloy can be appropriately selected and used. Practically, IN939, IN738, Ma
It is effective to use a Ni-based superalloy such as r-M247 or RENE80 or a Co-based superalloy such as FSX-414 or Mar-M509. These superalloys are composed of a parent phase in which various elements are dissolved and a precipitated phase such as a γ 'phase and a carbide. For Ni-base and Co-base superalloys,
The parent phase is the gamma phase. For example, in a Ni-base superalloy, the strength is improved by precipitation of an intermetallic compound phase based on Ni ₃ Al, which is a γ ′ phase, with respect to a mother phase. For example, the Al concentration of the parent phase in a Ni-based superalloy is usually about 0 to 3% by weight,
The Al concentration of the parent phase in the Co-based superalloy is usually 0 to 5% by weight.
It is about.

Further, the M-Cr-Al-Y alloy layer in the first and second metal coating materials contains 0.1 to 20% by weight.
Al, 10 to 35 wt% Cr, 0.1 to 1.5 wt% Y,
It is preferable to use an alloy having a composition in which the balance substantially consists of the M element. Al and Cr are elements that contribute to corrosion resistance, and if they are outside the above range, the function of the M-Cr-Al-Y alloy layer as a corrosion-resistant and oxidation-resistant coating layer cannot be sufficiently obtained. A more preferred composition ratio of Al and Cr is Al
Is in the range of 0.1 to 15% by weight, and Cr is in the range of 15 to 30% by weight. As described in detail later, Al is set within a range of ± 0.5% by weight of the Al concentration in the base material matrix within the above range. Y is an element for reinforcing and maintaining the strength of the protective oxide film, and the effect is reduced in any case outside the above range. A more preferable composition ratio of Y is in the range of 0.3 to 1% by weight. M element
At least one element selected from Fe, Ni, and Co may be used, but Ni or Co is particularly preferable, or a combination of Ni and Co or a combination of Co and Ni is preferable.

The coating layer composed of the M-Cr-Al-Y alloy layer can be formed by applying various thin film forming methods such as a plasma spraying method, a PVD method, and a CVD method. Thermal spraying is most preferred. Plasma spraying is
First, the surface of the base material is roughened by sandblasting or the like, and then the M-Cr-Al-Y alloy powder is melted using a plasma flame in a reduced-pressure atmosphere or under atmospheric pressure, and then attached to the surface of the base material by a gas flow. It is. The thickness of the M-Cr-Al-Y alloy layer is 50 ~
Preferably, the thickness is about 500 μm.

By the way, the above-mentioned substrate and M-Cr-Al
The movement of elements between the coating layers made of the -Y alloy usually occurs between the base alloy base phase (for example, γ layer) and the coating layers. Therefore, the concentration difference between the base alloy base phase and the coating layers causes mutual diffusion and reaction. Have a big impact. In particular, since Al is an element that plays a role in both the corrosion resistance and oxidation resistance of the coating layer and the strength of the base alloy, the behavior of Al is the main factor that determines the oxidation resistance of the coating material and the high-temperature strength characteristics of the base material .

In view of the above, in the first invention, the Al in the M-Cr-Al-Y alloy layer formed on the substrate is coated.
The concentration is within a range of ± 0.5% by weight of the Al concentration in the base material matrix within the range of the basic composition ratio described above. By forming an M-Cr-Al-Y alloy layer having such an Al concentration as a coating layer, a rapid diffusion reaction is suppressed, and a coating layer that does not impair the strength of the base alloy for a long time can be obtained.

In the first invention, when the Al concentration in the M-Cr-Al-Y alloy layer is lower than [the Al concentration in the base material matrix—0.5% by weight], the M-Cr-Al Since the diffusion of Al into the Al-Y alloy layer becomes remarkable, the disappearance rate of, for example, the γ 'phase, which is a strengthening phase of the base alloy, increases, and [Al concentration in base matrix + 0.5% by weight] If the amount is large, the diffusion of Al from the M-Cr-Al-Y alloy layer to the substrate becomes remarkable, so that the generation of an embrittlement phase in the substrate alloy is inevitable. Therefore, in any case, a rapid decrease in high-temperature strength cannot be avoided.

Further, the second metal coating material has a first coating layer composed of an M-Cr-Al-Y alloy layer and a second coating layer composed of an Al-rich layer laminated on the surface of the base alloy. When forming, the Al concentration in the M-Cr-Al-Y alloy layer is adjusted within the range of the basic composition ratio described above,
The range is ± 0.5% by weight of the Al concentration. Such Al
By forming the M-Cr-Al-Y alloy layer with a high concentration as the first coating layer, first, as in the case of the first metal coating material described above, between the substrate and the M-Cr-Al-Y alloy layer Rapid diffusion reaction can be suppressed and M-Cr-Al
It is possible to prevent the occurrence of defects such as pores inside the -Y alloy layer.

That is, the first layer made of the M-Cr-Al-Y alloy layer
The coating layer has an Al concentration of ±
Since the Al concentration is relatively low due to the range of 0.5% by weight, even when the Al-enriched layer is formed thereon as the second coating layer, the Al-enriched layer may be formed or used at the time of formation or use.
The formation of Al-rich intermetallic compounds inside the M-Cr-Al-Y alloy layer can be suppressed. This makes it possible to prevent defects such as pores from occurring inside the M-Cr-Al-Y alloy layer.

The Al-enriched layer in the second metal coating material is a layer that imparts corrosion resistance and oxidation resistance to the first coating layer made of an M-Cr-Al-Y alloy layer. This Al-enriched layer may be a layer containing Al at a higher concentration than the M-Cr-Al-Y alloy layer, and can be formed by an aluminum pack method, a coating method, a vapor deposition method, a plating method, etc. Above, it is preferable to apply the aluminum pack method. The thickness of the Al-enriched layer is 10 to 1
It is preferable that the thickness be about 00 μm.

In the aluminum pack method, M-Cr- is mixed in a mixed powder of a metal powder containing Al and an additive such as ammonium chloride or an aluminum oxide powder as a sintering inhibitor, or in steam generated from the mixed powder. This is a method of forming an Al-enriched layer by installing a substrate coated with an Al-Y alloy layer and heating the substrate to a temperature of about 600 to 1200 ° C in a hydrogen atmosphere. The Al-enriched layer formed by the aluminum pack method is basically made of a compound of Al and Ni, Co, Fe or the like. For example, when the M-Cr-Al-Y alloy layer is based on Ni, Ni ₃ Al, Ni ₅ Al ₃ , NiAl, Ni ₂ Al ₃ , NiAl ₃ etc. Is Co ₂ Al ₉ , Co ₄ Al
₁₃ , when Co ₂ Al ₅ , CoAl, etc. are based on Fe,
Intermetallic compound layers such as Fe ₃ Al, FeAl, FeAl ₂ , Fe ₂ Al ₅ , and FeAl ₃ are formed. Note that Ni, Fe, and Co may be substituted in each intermetallic compound.

[0021]

Embodiments of the present invention will be described below.

Example 1 As a base material, a Ni-base superalloy IN939 in which a γ 'phase as a reinforcing phase, a carbide phase, and the like were precipitated in a γ matrix phase was used. Table 1 shows the average chemical composition of the IN939 substrate and the results of elemental analysis in each phase using an elemental analyzer of a transmission electron microscope.

[0023]

[Table 1] After the above-mentioned base material was cut into a size of 20 × 20 × 5 mm, the surface was subjected to sandblasting (roughening) with alumina particles. And 47Ni-23Co-29Cr-0.7Al-
0.5Y (wt%) alloy powder in a reduced pressure atmosphere, arc current 950
A, Plasma spraying under the condition of voltage 35V, thickness about 200μm
Formed a Ni-Co-Cr-Al-Y alloy layer to obtain a target metal coating material.

On the other hand, as a comparative example with the present invention,
39 After subjecting the substrate surface to surface roughening treatment by sandblasting, 36Ni-23Co-29Cr-12Al-0 containing high concentration of Al.
5Y alloy powder was subjected to plasma spraying under reduced pressure to produce a metal coating material (Comparative Example 1). Each of the metal coating materials of Examples and Comparative Examples thus produced was subjected to a heat treatment at 850 ° C. for 3,000 hours in the air. After heat treatment,
The cross section of the sample was observed with a scanning electron microscope, and the thickness of the γ 'phase disappearance region in the IN939 substrate caused by interdiffusion at the coating layer / substrate interface was measured. As a result, the thickness of the γ 'phase disappearance region of the metal coating material according to the example is
The thickness of the γ 'phase disappearance region of the metal coating material according to the comparative example was 83 μm, compared with 7 μm.

As is apparent from the above measurement results, in the metal coating material of the present invention, mutual diffusion of elements between the coating layer composed of the Ni-Co-Cr-Al-Y alloy layer and the substrate is extremely slightly suppressed. Thus, formation of a deteriorated substrate layer such as a γ 'phase disappearance region can be suppressed. Therefore, even after long-time use, the substrate strength is hardly impaired.

Further, in the metal coating material according to the above embodiment, a very thin protective oxide film of Cr ₂ O ₃ is formed on the surface of the material, and the weight increase is about 1/2 compared to the IN939 substrate alone. Oxidation resistance was significantly improved. Also, compared to the metal coating material of Comparative Example 1 in which a Ni-Co-Cr-Al-Y alloy layer having a high Al concentration was formed, the weight increase was equivalent, and both high temperature strength and oxidation resistance were considered. Comprehensive evaluation reveals that the metal coating material of the present invention has better material properties.

Example 2 As a base material, a Ni-base superalloy IN738 was used in which a γ 'phase as a reinforcing phase and a carbide phase were precipitated in a γ matrix. Table 2 shows the average chemical composition of the IN738 base material and the results of elemental analysis in each phase using an elemental analyzer of a transmission electron microscope.

[0028]

[Table 2] After cutting the base material into a size of 20 × 20 × 5 mm, the surface was subjected to sandblasting treatment with alumina particles. Then, as shown in FIG. 1, γ ′ is contained in the matrix 1a composed of the γ phase.
58Ni-23Co- on the base material 1 in which the reinforcing phase 1b such as a phase is dispersed.
17Cr-1.5Al-0.5Y (wt%) alloy powder was plasma sprayed under reduced pressure atmosphere, under the conditions of arc current 900A and voltage 35V, and the thickness was approx.
A 200 μm Ni-Co-Cr-Al-Y alloy layer 2 was formed.

Next, the base material on which the Ni-Co-Cr-Al-Y alloy layer 2 is formed is embedded in a mixed powder of 50Fe-50Al (wt%) alloy powder, ammonium chloride and aluminum oxide, Diffusion and infiltration treatment at 900 ° C for 2 hours in a hydrogen atmosphere
Al-rich layer 3 on the surface of i-Co-Cr-Al-Y alloy layer 2
A 50 μm NiAl layer was formed. Thus, the target metal coating material 4 was produced.

On the other hand, as a comparative example with the present invention, as shown in FIG. 2, the surface of the IN939 substrate 1 is generally used after being subjected to a surface roughening treatment by sandblasting.
A 47Ni-23Co-17Cr-12Al-0.5Y alloy powder containing a high concentration of Al is plasma-sprayed under reduced pressure to form a Ni-Co-Cr-Al-Y alloy layer 5, and a metal coating material 6 (Comparative Example 2) ) Was prepared. Further, the base material 1 on which the Ni-Co-Cr-Al-Y alloy layer 5 having the same composition as that of the comparative example 1 was formed was subjected to a diffusion and infiltration treatment under the same conditions as in the example 2, and as shown in FIG. , Al-enriched layer 3 was formed to prepare metal coating material 7 (Comparative Example 3).

Each of the metal coating materials of Example 2 and Comparative Examples 2 and 3 produced as described above was used in a static atmosphere.
It was subjected to a continuous oxidation test at 800 to 1000 ° C. for 1000 hours. Table 3 shows the measurement results of the weight increase and the diffusion layer thickness after the oxidation test.

[0032]

[Table 3] As is clear from the above measurement results, even in the most severe oxidation test at 1000 ° C., the metal coating material of the present invention showed a weight increase of about 1/5 of Comparative Example 2 and about 2/3 of Comparative Example 3. The thickness of the γ 'phase disappearance region on the substrate side due to element diffusion was about 1/10 of Comparative Examples 2 and 3. In addition, a thin and dense Al ₂ O ₃ protective coating that was not observable with a scanning electron microscope was maintained on the sample surface even after the test. From these, the excellent oxidation resistance of the coating material of the present invention and the effect of suppressing the deterioration of the substrate due to the diffusion of the coating layer elements were clearly recognized.

Further, the above three types of metal coating materials were subjected to a heat cycle test between room temperature and 1000 ° C.
Table 4 shows the results.

[0034]

[Table 4] The metal coating material according to Comparative Example 3 exhibited relatively good oxidation resistance in the continuous heating test described above, but in the heat cycle test, as shown in FIG. 3, Ni-Co-Cr-A
Due to the pores 8 formed inside the lY alloy layer 5, Ni-C
The peeling of the o-Cr-Al-Y alloy layer 5 occurred at an early stage, and the oxidation resistance was significantly reduced. On the other hand, the metal coating material according to the example 2 has a Ni-Co-Cr-Al-Y alloy layer (coating layer) even after 3500 thermal cycles.
It was confirmed that Sample No. 2 was sound and had excellent heat cycle characteristics.

In each of the above embodiments, Ni-Co-Cr-Al was used as the M-Cr-Al-Y alloy constituting the coating layer.
Although the example using the -Y alloy has been described, the same effect was obtained when the M element was replaced with another element (at least one element selected from Fe, Ni and Co).

The metal coating material of the present invention as described above is suitable as a constituent material of high-temperature equipment used in an environment in which high temperature and high stress act on the material, such as gas turbine blades. Even when used below, excellent corrosion and oxidation resistance and high-temperature strength can be maintained for a long time. That is, by using the metal coating material of the present invention as a constituent material of a gas turbine blade, for example, the operating temperature and durability of the gas turbine are dramatically improved, and greatly contribute to the power generation efficiency and reliability of the power plant. Yes, its usefulness is extremely large.

[0037]

As described above, according to the first metal coating material of the present invention, the base metal alloy matrix and the M-Cr-Al
Since the diffusion reaction between the -Y alloy layers can be suppressed, it is possible to obtain a coating material having excellent corrosion resistance and oxidation resistance without impairing the strength of the base alloy for a long time. According to the second metal coating material,
It can suppress the rapid diffusion reaction between the base material and the M-Cr-Al-Y alloy layer, and when forming the Al-enriched layer, the M-Cr-Al
Since the occurrence of defects such as pores inside the -Y alloy layer can be prevented, the excellent material properties described above can be maintained. Therefore, even when used in an environment where high temperature and high stress act on the material, for example, in an environment where gas turbine blades are used, excellent corrosion resistance, oxidation resistance and high temperature strength can be maintained for a long time. It is possible to provide a metal coating material.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating a structure of a metal coating material according to a second embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically illustrating a structure of a metal coating material according to Comparative Example 2.

FIG. 3 is a cross-sectional view schematically illustrating a structure of a metal coating material according to Comparative Example 3.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base material 1a ... Matrix which consists of gamma phase 1b ... Reinforcement phase which consists of gamma prime phase etc. 2 ... M-Cr-Al-Y alloy layer 3 ... Al-rich layer 4, 6, 7 ... Metal coating Material 5: Conventional M-Cr-Al-Y alloy layer 8: Pore

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazuhiro Yasuda 1st Toshiba-cho, Komukai, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba R & D Center (72) Inventor Seiichi Suenaga Komukai-Toshiba-cho, Kochi-ku, Kawasaki-shi, Kanagawa No. 1 Toshiba Corporation R & D Center (56) References JP-A-6-220607 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23C 30/00

Claims (2)

(57) [Claims] At least one selected from Fe, Ni and Co
A base made of an alloy mainly composed of one kind, and an M-Cr-Al-Y alloy layer formed on the surface of the base (where M is Fe,
Indicates at least one element selected from Ni and Co)
Wherein the Al concentration in the M-Cr-Al-Y alloy layer is in the range of ± 0.5% by weight of the Al concentration in the matrix of the base material. Coating material. 2. At least one selected from Fe, Ni and Co
A base made of an alloy mainly composed of one kind, and an M-Cr-Al-Y alloy layer formed on the surface of the base (where M is Fe,
Indicates at least one element selected from Ni and Co)
Formed on the M-Cr-Al-Y alloy layer,
In a metal coating material comprising an Al-enriched layer containing Al at a higher concentration than the r-Al-Y alloy, the Al concentration in the M-Cr-Al-Y alloy layer is A metal coating material having an Al concentration in the range of ± 0.5% by weight.