JP2930497B2 - Method of forming high temperature corrosion resistant alloy spray coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to protection and performance of high-temperature exposed parts such as boilers, gas turbines, jet engines, and diesel engines, high-temperature members such as blast furnaces and heat treatment furnaces, and components such as rockets and space shuttles. The present invention relates to a method for forming a thermal spray coating (coating member) for improvement.

[0002]

2. Description of the Related Art It is well known that intensive development research is being conducted on driving engines, such as diesel engines, boilers, gas turbines, and jet engines, for the purpose of improving thermal efficiency.

[0003] However, an increase in thermal efficiency has at the same time resulted in a severe increase in the thermal load on those components. Therefore, the metal material used in the high temperature part of these driving engines is required to have high mechanical strength in a use environment and to have excellent resistance to high-temperature oxidation and high-temperature corrosion.

[0004] In particular, when a fuel containing impurities such as V, Na, and Pb is used, these impurity elements violently corrode and wear the metal material at a high temperature. It is necessary to maintain a stable state.

In order to meet such demands, heat-resistant alloys called so-called superalloys mainly containing non-ferrous metal elements such as Cr, Ni, Mo, Co, W, Ta, Al and Ti have been developed. Many have been developed. However, since these superalloys are premised on giving priority to high-temperature strength, the ratio of addition of a metal element that does not contribute to improvement in strength tends to be necessarily suppressed to a low level.

[0006] Representative of metal elements that do not contribute to the improvement of strength are
Al, Cr, and Si are useful metals with excellent oxidation resistance and high-temperature corrosion resistance. Poor corrosivity was common.

[0007] In view of such circumstances, for a superalloy member used in a high temperature environment, a metal or alloy such as Cr, Al, or Si is previously coated on the surface thereof by a thermal spraying method or a diffusion infiltration method. The method was applied to compensate for the reduced resistance of the superalloy to chemical damage.

However, the conventional thermal spraying method has an advantage that the kind of thermal spraying material can be arbitrarily selected, but the coating treated in the air has a disadvantage that it is porous and has poor adhesion. In this regard, in recent years, plasma spraying has been carried out in a low-pressure Ar gas atmosphere that does not substantially contain air (oxygen).
Although the low-pressure plasma spraying method has been developed and the disadvantages of the atmospheric sprayed coating have been greatly improved, this coating is not sufficient under recent high-temperature exposure environment conditions.

In the conventional diffusion infiltration method, Cr, Al, Si
It is relatively easy to treat each of them independently, but the oxidation resistance and hot corrosion resistance are not sufficient, and
Since it is necessary to perform the treatment at a high temperature of about 00 ° C., there is a disadvantage that the mechanical properties of the base material (superalloy member) deteriorate.

For such a situation, see, for example,
JP-A-04471 proposes a method of spraying a Ni-Cr alloy of an oxidation-resistant metal and then performing a diffusion and penetration treatment of Al or Cr. Although this method can be seen to improve the adhesion and denseness of the thermal sprayed coating, even in this method, the treatment at high temperatures that the diffusion and infiltration method has is unavoidable, so that the mechanical properties of the substrate are not reduced. I couldn't get it.

On the other hand, the development of thermal spraying materials used in a high-temperature environment of this kind has been actively conducted, and a heat-resistant alloy material represented by MCrAlX is known as a typical example.

In the above MCrAlX alloy, M is Ni, Co, Fe.
Alternatively, X is Y, Hf, Se, Ce, L
a, Th and other active elements, such as MCrAl
By subjecting the X alloy to low-pressure plasma spraying, it was possible to form a coating with extremely high oxidation resistance and high-temperature corrosion resistance, and the performance of high-temperature components could be further improved.

Japanese Patent Publication No. 61-10034 discloses this MC.
A method has also been proposed in which a thermal spray coating of rAlX alloy is formed and then Cr and Al diffusion and penetration treatments are performed.

However, even if the latest thermal spraying method and the thermal spray coating are combined with the diffusion and infiltration treatment, the durability of the gas turbine member used under a high temperature condition is insufficient as described below. Even if an excellent thermal spray coating was used, the mechanical properties of the substrate could not be reduced as long as the diffusion and infiltration treatment was combined.

That is, all commercially available MCrAlX alloys of various compositions are all alloyed (intermetallic compounds) in a vacuum melting furnace and have a very high melting point (a low melting point Al (660 ° C.)). Even if it contains, the melting point of the alloy as a whole is around 1400 ° C.) Since the coating has pores in the sprayed state, it is usually heated in a vacuum to 1000 to 1100 ° C to form the coating. Spray particles are bonded to each other to reduce porosity, and are also diffused into the base metal to improve the adhesion of the coating.
lX alloys require high-temperature heat treatment even after low-pressure plasma spraying (MCrAlX alloys require 900 to 10
Even when heated to a temperature of about 00 ° C, the mutual bonding reaction of the alloy particles constituting the coating and the bonding reaction with the base alloy are slow and inadequate, so a heat treatment at about 1100 ° C in a vacuum is required.) Therefore, there is a disadvantage that the mechanical properties of the base metal are inevitably reduced, and an increase in cost and labor due to the addition of an extra step (heat treatment step) is inevitable.

For a gas turbine blade material (Ni-based alloy), a sprayed coating of the above-mentioned prior art MCrAlX alloy is formed on the blade material, and then subjected to Cr or Al diffusion and penetration treatment to be used as an actual machine. In such a case, it is usual to go through the following heat history in order to improve the mechanical properties of the substrate caused by the diffusion and infiltration treatment. 1) After the thermal spray coating of MCrAlX alloy is formed, Cr and Al diffusion and infiltration treatment (heating at 900 to 1100 ° C for 5 to 10 hours) is performed. 2) After the treatment of 1) above, the solution treatment of the base material (Ni-based alloy) (1
(050-1150 ° C, 1-8 hours). 3) After the treatment in 2) above, aging treatment of the substrate (750 to 900 ° C,
1 to 10 hours).

Many MCrAlX alloys having various compositions according to the purpose of use have been proposed so far. Prior arts relating to these alloys are as follows. JP-A-58-37145, JP-A-58-37146,
JP-A-59-6352, JP-A-59-89745,
50-29436, JP-A-51-30530, JP-A-50-158
No. 531, JP-A-51-10131, JP-A-52-33842, JP-A-55-115941, JP-A-53-112234, JP-A-52-66836, JP-A-52-88226, JP-A-53-33931, JP-A-58-141355, JP-A-58-141355
JP-A-56-108850, JP-A-54-16325, JP-A-57-1
No. 55338, JP-A-52-3522, JP-A-54-66342
JP-A-59-118847, JP-A-56-62956, JP-A-51-33717, JP-A-54-65718, JP-A-56-93847, JP-A-51-94413, JP-A-56
-119766, JP-A-55-161041, JP-A-55-1
13871, JP-A-53-85829, JP-A-57-18595
No. 5, JP-A-52-117826, JP-A-60-141842
JP, JP-A-57-177952 and JP-A-59-1654.

The MCrAlX proposed in the above publication is
The chemical composition of the alloy is as follows.

As the M component, Ni: 0 to 75 wt%, Co: 0 to 70 wt%, F
e: 0 to 30 wt%, Cr: 5 to 70 wt%, Al: 1 to 29 wt% X component: Y: 0 to 5 wt%, Hf: 0 to 10 wt%, Other: Ta: 1 to 20 wt%, Si: 0.1 to 0.1 wt% 14wt%, B: 0
0.1 wt%, C: 0 to 0.25 wt%, Mn: 0 to 10 wt%, Zn: 0 to 3 wt%, W: 0 to 5.5 wt%,
Pt: 0-20wt% etc.

[0020]

SUMMARY OF THE INVENTION An object of the present invention is to provide MCrA
Improve the performance of the lX alloy as a thermal spray coating and achieve coating properties equivalent to or better than those obtained by using the diffusion infiltration method without causing a decrease in the mechanical properties of the superalloy substrate due to high-temperature heating (high denseness) , Adhesion).

The present invention has solved the above-mentioned problems by employing the technical means described below. That is, the present invention provides (1) a method of forming a film on a substrate by low-pressure plasma spraying using an MCrAlX alloy, a layer of an MCrAlX alloy material and a layer made of an alloy material obtained by further adding free metal Al to these materials. A thermal spray coating is formed by alternately stacking the layers, and heated for 1 hour or more at a temperature of 700 ° C. or more in a vacuum furnace or in a vacuum furnace. (2) Add the free metal Al to the MCrAlX alloy material After forming the sprayed coating of the material consisting of the above material, it is heated for 1 hour or more at a temperature of 700 ° C or more in a vacuum furnace using an arc of reduced pressure plasma. (3) After forming the sprayed coating of the MCrAlX alloy material Then, a sprayed coating of the released metal Al is further formed on this coating, and the sprayed coating is formed using a vacuum plasma arc or in a vacuum furnace.
Heating at a temperature of at least 1 ° C for 1 hour or more, thereby dissolving the metal Al released and aiming at densification of the thermal spray coating and improvement of adhesion to the substrate metal without deteriorating the mechanical properties of the substrate .

[0022]

[Function] First, the thermal spray coating (metal
Regarding the mechanism of action of the plasma sprayed coating of the MCrAlX alloy to which Al is added, the difference from the previously known MCrAlX alloy will be described.

As can be understood from the chemical composition, MCrAlX alloy is composed of a metal element having a strong chemical affinity with oxygen. Therefore, it is common to use a vacuum melting furnace to alloy the alloy. It is. MC melted in a vacuum melting furnace
rAlX alloys cause a mutual metallurgical reaction in the molten state, causing many alloys and intermetallic compounds (e.g., NiAl, Ni ₃ Al, Co
_{Since 3} Ti, Ti ₃ Al, FeAl, CrAl, and Cr ₃ Ta ₂ ) are produced, even if they are used for thermal spraying, their physicochemical properties show properties as alloys and intermetallic compounds.

For this reason, even if the MCrAlX alloy contains an Al component having a low melting point, its melting point is as high as that of the alloy (1400).
(Approximately 100 ° C.), a heat treatment of heating to at least about 1100 ° C. is necessary in order to densify the coating after thermal spraying of such an alloy material, and a sufficient degree of particle bonding cannot be obtained even with this.

In the present invention, in the process of pulverizing an MCrAlX alloy produced by vacuum melting as a thermal spraying material, or after producing as a powder, a metal Al powder is added to the powder.
Different from the solid solution alloyed Al contained in the lX alloy, it exhibits physicochemical properties as free metal Al.

That is, free metal Al as in the present invention
The MCrAlX alloy with the addition of
It is characterized by showing two kinds of physicochemical properties of rAlX alloy and liberated metal Al. For this reason, even if it is heated to only about 700 ° C., the film is sufficiently densified.

In the present invention, in order to prevent oxidation of free metal Al, it is optimal to use a reduced pressure plasma spraying method. However, a spraying method in which a gas such as Ar, N ₂ , He or the like is supplied to block air from entering. As long as the atmosphere is used, atmospheric pressure plasma spraying can be easily performed. In addition, the plasma flame during depressurization increases the speed of the flame as compared with the atmosphere of the same output, and the temperature decreases, so in the case of spraying the MCrAlX alloy containing low melting point metal Al, the decompression plasma spraying method is particularly preferable. .

In the present invention, since the free metal Al is in a molten state even during the thermal spraying, the MCrA containing only the solid-solution alloyed Al having the same composition even in the state where the thermal sprayed film is formed.
Compared with the lX alloy film, there is an advantage that a good quality film with much less pores can be obtained.

The particle size of the MCrAlX alloy (alloy containing solid solution alloyed Al) suitable for the present invention is suitably from 10 to 80 μm. This is because if the particle diameter is smaller than this, fumes (fumes) are generated at the time of spraying, and it is difficult to stably supply the sprayed particles to the spray gun, while the particle diameter is smaller than 80 μm. If the particle size is large, unmelted particles increase and it is not advisable.

As for the amount of free metal Al added to the MCrAlX alloy, the effect is recognized even at 0.2 wt% because the specific gravity (2.7) is light, and the content of solid solution alloyed Al in the MCrAlX alloy is small. Alloy, for example, 10wt% Ni-57wt% Co-25wt% Cr-3
wt% Al-0.5wt% Y-5wt% Ta alloy has 25wt%
An excellent film can be obtained even if added so that

The preferred range of the amount of the free metal Al varies depending on the content of the solid-solution alloyed Al in the MCrAlX alloy. However, for a commercially available MCrAlX alloy, 0.5 to 15 wt.
A range of% can be recommended. As described above, the content of solid solution alloyed Al in the MCrAlX alloy in the prior patent is 1 to
Although it is in the range of 29wt%, this solid solution alloyed Al is 1-10wt%
For those within the range, the addition of 10-15 wt% of free metal Al, and for alloys containing higher solid solution alloyed Al, the addition of free metal Al of 0.5-10 wt% It is appropriate to set the range.

For example, Ni-17% Cr-1% Al-3%
W- 0.3% Y- 0.1% Hf- 0.1% Cs, Ni-15% Cr-
6% Al-0.5% Y-0.8% Mn-0.3% B-0.2% Th,
Ni-15% Co-18% Cr-10% Al-0.8% Y-0.5% Ta-
For alloys such as 0.1% Ce-0.1% Cs, free metal Al
Is preferably in the range of 10 to 15% by weight. In addition, Ni-20% Cr-12% Al-0.8% Y, Ni
-15% Cr-17% Al-0.5% Y-00.% Cs, Ni -15%
For alloys such as Co-29% Al-0.9% Y-0.8% Ta-0.1% Ce, the amount of free metal Al added is preferably in the range of 0.5 to 10 wt%.

As a method for adding free metal Al to the MCrAlX alloy, a mechanical alloying method using an alloy powder or a mechanophase method (document: Hosokawa Micron Co., Ltd., Powder Engineering Laboratory, edited by "Mechanofusion" Nikkan Kogyo It is suitable to be manufactured by Shimbunsha (fermented on June 1, 1989), but it is also possible to use a vapor deposition method. The purity of the metal Al to be used only needs to be commercially available Al (three kinds of JIS H 2102, Al purity 99% or more). . It should be noted that the present invention is not particularly limited because it is not particularly affected by ordinary impurity elements contained in the Al metal.

FIG. 1 shows that a coating 2 having a thickness of 80 μm is formed by thermal spraying on the surface of a substrate 1 using a normal MCrAlX alloy, and then a coating is formed on the coating by using an MCrAlX alloy to which free metal Al is added. This shows a cross section of a main part when the operation of forming a film 3 having a thickness of 30 μm is alternately repeated twice. When this film is heated in a plasma frame or vacuum furnace to about 700 ° C., which is higher than the melting point of free metal Al, only the free metal Al in the film melts, causing a metallurgical reaction with the unmelted MCrAlX alloy and causing the unmelted alloy to interact. The bonding force of the metal is increased, and the pores of the film can be eliminated, and at the same time, the free metal Al itself causes a metallurgical reaction with Ni, Co, Cr in the MCrAlX alloy and the melting point rises, and it is used in a high temperature real environment Nothing really matters.

FIG. 2 shows a cross section of the coating 4 when a thermal spray coating is performed by using a material obtained by adding a free metal Al to a normal MCrAlX alloy and mechanically mixing it. By heating the film, the same effect as in FIG. 1 can be obtained.

FIG. 3 is a diagram showing a conventional MCrAlX alloy having a thickness of 20 mm.
0 μm coating 2 is sprayed and then free metal
This shows a cross section when a film 5 having a thickness of 20 μm is formed by thermal spraying using Al. When this film is heated to about 700 ° C in a plasma frame or vacuum furnace, only the metal Al film melts and diffuses and penetrates into the underlying MCrAlX alloy film, reducing pores in the film and interconnecting MCrAlX alloy particles. Effects such as an improvement in power are obtained.

As described above, after the film is formed, the heat-treated film necessarily contains a large amount of Al.
This coating is more excellent in high-temperature oxidation resistance than spray coating of lX alloy.

[0038]

Example 1 Example 1 Ni alloy (15.3 wt% Cr-7 wt% Fe-2.5 wt% Ti-2 wt% Mo
-10 wt% Co-remaining Ni,) was processed into a plate-like test piece having a width of 30 mm, a length of 50 mm, and a thickness of 5 mm, and a sprayed film was formed on one surface of the test piece by a low pressure plasma spraying method according to the following procedure.

(1) Thermal spray material (MCrAlX alloy) (A) 10% Ni-56.5% Co-25% Cr-3% Al-5% Ta-0.5% Y. (B) 76.5% Ni-17% Cr- 6% Al-0.5% Y. (C) 63.4% Co-23% Cr-13% Al-0.6% Y. (2) MCrAlX alloy with added free metal Al. (D) (A) free metal Al (E) (B) free metal Al added to 5%. (F) (C) free metal Al added to 5%. thing.

In the present embodiment, as shown in FIG.
First, the normal MCrAlX alloys (A), (B) and (C) were sprayed onto the surface of each test piece so that the thickness was 80 μm, respectively.
(A) is sprayed, and (D) is further added on it.
(B) is sprayed, and (E)
In the case of (C), the operation of spraying the MCrAlX alloy of (F) so as to have a thickness of 30 μm was alternately repeated twice, and the total thickness was 220 μm. Thereafter, each of the test pieces was placed in a vacuum furnace at 700 ° C, 800 ° C.
C., 900.degree. C., 1000.degree. C., and 1100.degree. C., each was heated for 1 hour, cooled in a furnace, the cross section of the coating was observed with an optical microscope, and the porosity of the coating was measured with an image analyzer. The results are shown for ordinary MCrAlX alloy ((A) only,
Table 1 shows the results of thermal spraying under the same conditions in a vacuum furnace after thermal spraying using (B) only and (C) only) to a thickness of 220 μm.

[0041]

[Table 1]

In Table 1, the sprayed coatings of Comparative Examples (Nos. 1 to 3) had a porosity in the range of 0.5 to 1.2% immediately after spraying.
The porosity gradually decreases by heating this, but it shows a porosity of about 0.3 to 0.6% even after heating to 1000 ° C, and finally 0.1 to 0.3% when heated to 1100 ° C.
The decrease in porosity due to heating was very slow.

On the other hand, in the present invention (Nos. 4 to 5), the porosity of the coating immediately after thermal spraying has already been reduced to 0.1 to 0.4% due to the effect of the addition of free metal Al. It was confirmed that the effect of the heat treatment was very strong, for example, the porosity was 0.1% or less. In addition, in the present invention, diffusion of Al into the base alloy during the heat treatment of the film was sufficiently recognized, and it was confirmed that a great effect could be expected to improve the adhesion.

Example 2 Metallic Al was added to an MCrAlX alloy having the following composition and mechanically mixed, and the resulting mixed powder was used as a thermal spraying material to form a film by a plasma spraying method. Was investigated for its denseness.

(1) Thermal spray material (MCrAlX alloy). (A) 10% Ni-56.5% Co-25% Cr-3% Al-5% Ta-0.5% Y. (B) 76.5% Ni-17% Cr -6% Al-0.5% Y. (C) 63.4% Co-23% Cr-13% Al-0.6% Y. (2) MCrAlX alloy with free metal Al added. (D) Free metal Al added to (A). (E) Addition of free metal Al to 8% in (B). (F) Addition of free metal Al to 8% in (C). (3) Mixing ratio of the thermal spray coating of the present invention (% by weight). 1) A film having a thickness of 200 μm was formed by mixing (A) 50% and (D) 50%. 2) (B ) A film with a thickness of 200 μm is formed by mixing 40% and (E) 60%. 3) A film with a thickness of 200 μm is formed by mixing (C) 30% and (F) 70%. 4) (A) 50% and (B) 70% are mixed to form a 200 μm thick film. 5) (B) 20% and (B) 80% are mixed to form a 200 μm thick film. Deposited in thickness.

Each of the thermal sprayed coatings was placed in a vacuum furnace at 750 ° C., 2
After heating for a time, the porosity of each of the films was 0.03 to 0.1%, and it was confirmed that the films were very dense.

Example 3 The surface of the test piece made of the Ni-based alloy used in Example 1 was (A)
A 200 μm-thick film was spray-sprayed using an MCrAlX alloy having the following composition, and then pure Al (purity 99.
(5%) was spray-coated to a thickness of 20 μm to obtain a film having a structure as shown in FIG. The obtained test specimen was heated in vacuum to 700 ° C, 800 ° C, 900 ° C, and 1000 ° C, respectively.As a result, the metal Al in the uppermost layer of the coating was completely melted and moved into the MCrAlX alloy layer that constituted the lower layer. And the porosity of the sprayed coating was significantly reduced (0.01 to 0.1%).

Example 4 Using a test piece of a Ni-based alloy (the composition was the same as in Example 1) having a width of 30 mm, a length of 50 mm and a thickness of 3 mm, the surface thereof was treated under the following conditions (MCrAlX alloy with metal Al addition). ) + (MCrAlX with no metal Al added)
Alloy) was formed and the high-temperature corrosion resistance was investigated.

(1) Types of thermal spraying materials to be tested (A) 10% Ni-56.5% Co-25% Cr-3% Al-5% Ta-0.5% Y. (B) 76.5% Ni-17% Cr -6% Al-0.5% Y. (C) 63.4% Co-23% Cr-13% Al-0.6% Y. (D) (A) to which 5% of free metal Al is added. E) Free metal Al added to 5% to (B). (F) Free metal Al added to 5% to (C). (G) Free metal Al (purity 99.5) (2) Structure of thermal sprayed coating (order and film thickness from Ni-base alloy side). (1) (A) 80 μm + (D) 30 μm + (A) 80 μm + (D) 30 μm. (2) ( (B) 80 μm + (E) 30 μm + (A) 80 μm + (E) 30 μm. (3) (C) 80 μm + (F) 30 μm + (C) 80 μm + (F) 30 μm. (4) (A) 200 μm + (G) 20 μm. (3) Heat treatment conditions. All heat treatment conditions were heating at 800 ° C. for 1 hour in a vacuum furnace. (4) Types of high-temperature corrosion test and corrosion conditions. 1) Vanadium corrosion test: Chemical composition 80% V ₂ O ₅ -20% Na ₂ SO _4. Temperature / time 900 ° C, 3 hours. 2) High-temperature sulfide corrosion test. ： Drug composition 90% Na ₂ SO ₄ -10% NaCl. Temperature ・ time 1000 ℃ 、 4 hours. In both tests, the applied amount of drug was 1cm ² of sprayed coating.
25 mg (25 mg / cm ² ), the temperature and time were maintained at a predetermined value in electricity, and then the sample was taken out, the cross section of the corroded portion was examined with an optical microscope, and the penetration depth of the corrosive agent component was measured to evaluate the corrosion resistance. Table 2 shows the results.

[0050]

[Table 2]

The comparative examples (Nos. 1 to 3) in Table 2 show the results of corrosion tests on the thermal spray coatings of ordinary MCrAlX alloys ((A), (B), (C)). As is clear from the results, it can be seen that the penetration depth of vanadium and the sulfur compound is large and the corrosion resistance is poor for the film of the comparative example. On the other hand, in the thermal spray coating according to the present invention (Nos. 4 to 7), the penetration depth of these corrosive components is 5 to 20 μm in the vanadium corrosion, compared to the erosion depth of 20 to 70 μm in the comparative example.
, Even in high temperature sulfurization corrosion, 15-30μm compared to the former 22-70μm
It was confirmed that it exhibited excellent high-temperature corrosion resistance.

The chemical components of the MCrAlX alloy used in the above embodiments include Ni, Co, Cr, Al, Ta, and Y. As described above, the MCrAlX alloy contains Hf, C
Some include s, Ce, La, Th, W, Si, Mn, and B, and the types of chemical components are extremely large. However, as is evident from the action mechanism and examples of the present invention, the free metal Al added to this type of MCrAlX alloy utilizes the action of exhibiting a physical behavior (particularly, melting point) different from that of alloyed Al. Therefore, it sufficiently exerts its function even on MCrAlX alloys containing metal elements other than the examples. Therefore, in the present invention,
The present invention is not limited to the MCrAlX alloy, but can be widely applied to this kind of heat-resistant and oxidation-resistant alloy.

Example 5 The high temperature properties of the MCrAlX alloy powder containing free metal Al were further
In order to confirm well, a differential thermal analyzer (manufactured by Vacuum Riko,
Investigation was carried out using a thermogravimetric analyzer TGD-3000). Offering
The alloy of the comparative example tested is a commercially available 32.8wt% Ni-21.4wt% Cr.
-8.90wt% Al-0.41wt% Y-36.49wt% Co
After the metal components are melted in vacuum, the powder
It is a shooting material. Further, the MCrAlX alloy of the present invention has the above-mentioned ratio.
Metal powder is further added to the comparative alloy by the mechanical alloying method.
It is made by adding powdered Al to 5 wt%.
You.

FIG. 4 shows the results of thermal analysis of these samples.
It is a thing. In the figure, 1-1 is the temperature scale, 1-2 is
Commercially available MCrAlX alloy powder, 1-3 is free metal Al of the present invention.
4 is a thermal analysis curve of an MCrAlX alloy powder containing the same. As shown in this figure
As is clear from the results, the commercially available MCrAlX alloy powder
Even when heated from room temperature to 900 ° C, there is no thermal change during this time.
unacceptable. That is, each of the gold constituting the MCrAlX alloy
Alloys are completely alloyed and change in the temperature range up to 1000 ° C.
It does not change. In contrast, the liberation of the present invention
As the temperature of the MCrAlX alloy powder containing metallic Al increases, 660
It is recognized that a sharp exothermic reaction occurs around ℃. This
Can be explained as follows. That is, 660 ° C is
Since it is the melting point of Al, Al melts at this temperature and MCrAlX
Metallurgical reaction with the alloy components, resulting in the resulting metal
Heat is generated by the heat of formation of the inter-compound. example
For example, if Al and Ni react to form NiAl , 118kj / mol
As the heat of formation is generated, its melting point rises to 1639 ° C
It is known that (Edited by `` The Chemistry of Combustion Synthesis ''
Combined Research Group Publisher Issued by T.I.C.
 May 20, 1992, page 34 Table 1 Heat of formation, melting point
And adiabatic combustion temperature)

As is clear from the above experimental results,
Ming's thermal spray material retains the original properties of metal Al and MCrAlX alloy
Al melts at low temperatures, resulting in a thermal spray coating
Suppress the generation of pores and the particles that constitute
It has been found that it has an action mechanism.

[0056]

According to the present invention, the porosity of the sprayed coating of such an alloy is controlled while preventing the mechanical properties of the base material, which cannot be avoided when forming the sprayed coating using the MCrAlX alloy, from being prevented. Adhesion and high-temperature corrosion-resistant film characteristics can be significantly improved. Further, according to the present invention, heat treatment of the thermal sprayed coating at a high temperature can be avoided, which is advantageous not only for energy saving but also for simplifying the process.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a thermal spray coating formed according to the present invention.

FIG. 2 is a schematic sectional view of a thermal spray coating formed according to the present invention.

FIG. 3 is a schematic sectional view of a thermal sprayed film formed according to the present invention.

FIG. 4 is a comparison diagram of thermal analysis curves of a commercially available thermal spray material and the thermal spray material of the present invention.

[Explanation of symbols]

 1 Base material 2 Coating (MCrAlX alloy) 3 Coating (MCrAlX alloy with free metal Al added) 4 Coating (free metal Al added and mechanically mixed) 5 Coating (free metal Al)

Claims (3)

(57) [Claims] An alloy material containing at least two of Co, Ni, Cr and Al, or Y, Hf, Ta
, Cs, Ce, La, Th, W, Si, Mn, B, a layer made of an alloy material to which at least one kind is added, and an alloy material containing free metal Al which is not further alloyed with these alloy materials After forming a thermal spray coating with alternating layers, 700
A method for forming a high-temperature corrosion-resistant alloy sprayed coating, wherein the coating is heated at a temperature of not less than 1 ° C. for at least 1 hour. 2. An alloy material containing at least two of Co, Ni, Cr, Al, or Y, Hf, Ta
, Cs, Ce, La, Th, W, Si, Mn, B, etc. After forming a thermal sprayed coating of an alloy material containing free metal Al, which is not further alloyed with an alloy material containing at least one of the above, 700 ° C or more A method for forming a high-temperature corrosion-resistant alloy sprayed coating, comprising heating at a temperature of 1 hour or more. 3. An alloy material containing at least two of Co, Ni, Cr, Al, or Y, Hf, Ta
, Cs, Ce, La, Th, W, Si, Mn, B, etc., after forming a thermal sprayed coating composed of an alloy material containing at least one of them, a thermal sprayed coating of unalloyed free metal Al on the thermal sprayed coating Forming a high-temperature corrosion-resistant alloy sprayed film by heating at a temperature of 700 ° C. or more for 1 hour or more.