JP2002106360A - Part for gas turbine and gas turbine having the part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide wear resisting surface treatment through which the wear damage of a gas turbine part can be effectively prevented from occurring. SOLUTION: A wear resisting coating layer 3 is formed on a base material 1 by using a thermal spraying material containing 75% or more of rigid particle, such as Cr3C2. A bonding coating layer having an intermediate nature between the natures of a wear resisting coating layer and the base material is interposed between the wear resisting coating layer 3 and the base material 1 to improve adhesion of the wear resisting coating. CoNiCrAIY is used as a binder material contained in a wear resisting coating layer 3. Further, Cr penetration treatment is applied on the wear resisting coating layer 3 to cure a surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas turbine component provided with a wear-resistant coating by thermal spraying and a gas turbine provided with the component. TECHNICAL FIELD The present invention relates to a coating technique for preventing abrasion damage caused by a coating.

[0002]

2. Description of the Related Art Generally, a mechanical device is subjected to mechanical vibration during its operation, so that abrasion damage may occur at a contact portion between components constituting a mechanical component. Among them, a gas turbine uses high-temperature gas generated by burning fuel to generate rotational motion and to use it for driving a generator, etc., so that vibration accompanying rotational motion occurs and combustion vibration generated by combustion itself. Occurs in the combustor. This combustion vibration is a high frequency vibration of several hundred hertz due to a change in gas pressure, and is considered to mainly vibrate in the axial direction.

[0003] Generally, a gas turbine is constructed as shown in Fig. 11, in which discharge air compressed by a compressor provided coaxially with the gas turbine is guided to a gas turbine combustor, and fuel is supplied to a liner of the combustor. The combustion gas is burned, and the combustion gas is guided from the liner to the moving blade via the transition piece and the stationary blade, and the gas turbine is driven to perform work.

In a combustor liner, as shown in FIG. 12, fuel is injected from a cylindrical end face, and the fuel is burned together with air introduced from an air hole provided on an outer peripheral surface of the liner. The combustion gas is guided to the stationary blade and the moving blade via the transition piece to drive the gas turbine. Since the combustor is heated by the combustion gas in such a short time, a fitting structure made of a thin plate is adopted in order to absorb thermal deformation caused by the combustion gas. For example, a structure called a spring seal is used at the joint with the transition piece shown in FIG. The spring seal is a plurality of leaf springs provided on the outer peripheral portion of the liner, and has a structure in which a transition piece is fitted into this portion to be integrated. The thermal strain generated in the liner by the leaf spring portion is taken in to prevent breakage due to heat.

[0005] Therefore, the above-mentioned combustion vibration generated by combustion is also concentrated in this portion, and in this portion, damage such as wear due to abrasion or damage due to thinning, and crack generation may occur. In this portion, the two are always in contact with each other, so that sliding wear along the contact surface is the main form of damage.

In addition, the liner main body vibrates in the axial direction in the liner stopper portion of FIG.

[0007] Generally, since the components of the combustor are connected in a fitted state, it is considered that abrasion due to sliding and abrasion due to knocking are mixed.

[0008] The above-mentioned damage and thinning due to abrasion may be remarkable even after about 1000 hours of operation under severe operating conditions, and the following three methods are available as countermeasures. (1) A method of reducing wear damage by improving the contact state of parts and improving the structure for suppressing combustion vibration, that is, reducing the contact surface pressure by changing the local point contact state to the surface contact state to reduce wear. (2) a method of reducing the amount of wear or reducing the amount of wear by applying a material having high wear resistance to a structure that was loose in consideration of thermal expansion and limiting combustion vibration; That is, a method such as applying a material having high wear resistance such as a super alloy in consideration of abrasion to a portion where ordinary stainless steel is sufficient in strength from an operating temperature; and (3) reducing wear damage This is a method of applying various coatings, that is, a method of coating a material having a hardness higher than that of the base material to reduce the amount of thinning. In this case,
Usually, a high-hardness material such as Cr ₃ C _{2 is} used as a coating material, and a method of spraying at a high speed called high-speed gas flame spraying is usually employed.

However, in spite of the various measures described above, it is a fact that there is no decisive factor for wear damage particularly in the combustor, which is shorter than the inspection interval of other component parts of the gas turbine. Inspections must be performed at timed intervals, which increases the operating and repair costs of the gas turbine.

[0010]

The above-mentioned three methods have been described as methods for reducing wear due to combustion vibration. However, the material change of the member (2) can be achieved by selecting from among heat-resistant materials for combustors. Since the selection is made in consideration of the cost, the manufacturing method, and the like, the applicable range is limited. In some cases, it is used on the assumption that parts are replaced or repair welding is performed. Therefore, for parts that can be easily replaced and do not require high-temperature strength, even if stainless steel or carbon steel is used in consideration of parts replacement during inspection, even if viewed from the overall operation cost, In some cases, the cost may be reduced.

In the structural improvement of (1), unless the fitting structure of the combustor is basically changed, the design is locally changed, and there is a point that the solution is not a fundamental solution. However, the current structure is determined in consideration of thermal deformation at the time of starting the gas turbine, hydrodynamic constraints, inspection workability, etc. Since there is no mating part, even if there is no problem with wear, cracks may occur in the stress concentration part due to thermal deformation due to complete restraint, and maintenance requires a lot of time for inspection. This causes other adverse effects, such as a large decrease in the cost, and is not necessarily a decisive measure.

As described above, in the current gas turbine combustor having the fitting structure, the wear-resistant coating (3) is the most effective means. In particular, where parts cannot be easily replaced and expensive materials have to be applied, no other method is conceivable.Even if the coating itself is reduced in thickness, re-coating can be applied. The merit is great, such as being able to recover to the state.

However, at present, there is no problem regarding the material of the abrasion-resistant coating, and a coating material for further reducing the abrasion amount and a coating material usable at a higher temperature are required. The realization of high coating materials and construction methods is an important technical issue.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a high-performance wear-resistant surface treatment, thereby improving the durability of a gas turbine.

[0015]

To achieve the above object, the present invention employs the following means. First, the first means is to increase the content of hard particles constituting the wear-resistant coating layer, for example, the content of Cr ₃ C ₂ to more than 75%. That is, in the current thermal spray material, the content of the hard particles Cr ₃ C _{2 as} the main component is 75%,
As a binder for binding the hard particles, for example, NiC
Although r is used at 25%, the abrasion resistance is improved by increasing the ratio of hard particles.
The improvement in the ratio of the hard particles can be achieved, for example, by improving the spraying conditions so that the speed of the sprayed particles at the time of spraying is 600 m / m.
By setting it to s or more, it can be realized without deteriorating the quality of the thermal spray coating. By performing thermal spraying at a high particle velocity, that is, at a high collision velocity, a wear-resistant coating layer (film) having a Cr ₃ C ₂ content or more that is currently used can be formed, and the volume ratio of hard particles increases. This makes it possible to increase the macro hardness of the sprayed coating and improve the wear resistance.

The second means is to use CoNi having high heat resistance as a material of a binder constituting the wear-resistant coating layer.
CrAlY, NiCoCrAlY and CoCrAlY
Or other materials represented by MCrAlY (where M is a metal). In this way, it is possible to prevent a decrease in strength due to oxidation and deterioration of the binder in an oxidizing atmosphere, and to maintain stable wear resistance for a long time under high temperature conditions.

A third means is to interpose a bond coat layer having an intermediate property (particularly ductility) between the wear-resistant coating layer and the base material. Thereby, the adhesion of the wear-resistant coating layer can be improved,
As a result, the durability of the wear-resistant coating layer can be improved.

The fourth means can be applied when the hard particles constituting the wear-resistant layer coating layer are Cr carbides.
This is to perform a Cr infiltration treatment on the wear-resistant coating layer containing a carbide by a powder method, a gas method, a molten salt method, or the like. As a result, the Cr on the surface of the wear-resistant coating layer
The carbide (for example, Cr ₃ C ₂ ) is transformed into a Cr carbide having a higher Cr content (for example, Cr ₇ C ₃ or Cr ₂₃ C ₆ ), but the Cr carbide having a higher Cr content has a lower Cr content. Since the hardness is higher than that of Cr carbide, the wear resistance of the wear-resistant coating layer can be increased.

The fifth means is used in place of the fourth means.
And performing the Cr infiltration treatment in the fourth means.
Alternatively, a Cr carbide having a high Cr content (for example,
Cr ₇C_ThreeAnd Cr_{twenty three}C₆) As hard particles
Applying a coating layer on the wear-resistant coating layer.
You. This also provides an effect approximately equivalent to that of the fourth means.
You.

A sixth means is to improve the shape of the thermal sprayed material so that the conventional solid spherical powder shape is made into a hollow shape (or a pseudo hollow shape according to the same), thereby improving the heating property and the acceleration by the flame. It is intended to improve the performance and to enable high impact velocity thermal spraying. In the case of spraying large-diameter particles with normal thermal spraying, heating is not uniformly performed up to the center, so that unevenness in strength occurs within the particles in the degree of film formation, and a film with sufficient strength is not formed. By doing so, heating can be performed uniformly as much as small-diameter particles, and a film can be formed with sufficient strength. Further, the apparent density per unit volume can be reduced, so that the flame can be easily accelerated to a high-speed flame speed (for example, 1500 m / s or more), and high-speed spraying can be performed. By applying such hollow particles, the handling of the sprayed powder becomes easy, and the spraying workability can be improved.

[0021] The seventh means includes ZrC, HfC, NbC,
A material having excellent hardness and density, such as TaC, WC, and Mo ₂ C, is used as hard particles constituting a wear-resistant coating. When applying the sixth means, the fifth means
It is preferable to use the means in combination. By using the fifth means in combination, ZrC, HfC,
Materials such as NbC, TaC, WC, and Mo ₂ C can be easily used as hard particles for the wear-resistant coating layer.

Although the above seven means are effective when used alone, the effect can be increased synergistically when used in combination.

[0023]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a configuration of a wear-resistant surface treatment according to the present invention. As shown in FIG. 1, a bond coat layer 2 is formed on a base material 1 by thermal spraying, and a wear-resistant coating layer 3 is formed on the bond coat layer 2.

The wear-resistant coating layer 3 is formed of hard particles and a binder.
The content of Cr ₃ C ₂ as hard particles is set to more than 75% by weight, and the content of the binder is set to 25% by weight or less.
The wear resistance of the wear-resistant coating layer 3 is improved by increasing the content of the hard particles as compared with the conventional one. Note that when the content of the hard particles contained in the thermal spray material is increased, thermal spraying becomes difficult. However, this problem is solved by performing thermal spraying from a thermal spray gun at a speed at which the particle speed of the thermal spray material becomes 600 m / s or more. be able to.

FIG. 2 is a schematic diagram for explaining a situation in which thermal spraying is performed by a thermal spray gun. As shown in FIG. 2, the spray gun 4 has a structure in which the spray material is accelerated together with the combustion gas. The fuel is supplied to the gun body together with oxygen in a high pressure state, and the completely burned gas flame 5 forms a supersonic jet stream. And released to the outside.

On the other hand, the thermal spray material 6 is introduced in a powder state from the rear of the gun body into the center of the gas flame 5 by an inert gas, and is jetted as high-temperature, high-speed flying particles along with the flow of the combustion gas. You.

The material that mainly contributes to the wear resistance of the film is Cr carbide, but since the bonding property between Cr carbides is low, a binder material for joining these carbide particles is sprayed simultaneously. As the binder material, the conventional material N
iCr may be used, but CoNiCrAlY, NiC
It is more preferable to use a material excellent in heat resistance represented by MCrAlY (where M is a metal) such as oCrAlY and CoCrAlY. This material is more excellent in high-temperature oxidation resistance than the conventional NiCr binder and can maintain the bond between the Cr carbide particles for a long time, so that the wear resistance of the wear-resistant coating layer 3 under high-temperature conditions is improved. , Can be stably maintained for a long time.

The particle velocity at the time of thermal spraying can be increased to 1000 m / s or more by improving the fuel conditions and pressure. In this case, the film forming speed can be further increased, and the particle speed can be increased. Not dense film can be made thicker.

Next, the bond coat layer 2 will be described.
The bond coat layer 2 is provided for the purpose of improving the adhesion of the wear-resistant coating layer 3 to the base material 1 and thereby greatly improving the durability of the wear-resistant coating layer 3. In other words, when the wear-resistant coating layer is applied directly to the base material as in the past, the ductility of the wear-resistant coating layer is smaller than that of the base material,
Also, due to the formation of an oxide layer at the boundary between the base material and the wear-resistant coating layer due to long-term use,
In some cases, the wear-resistant coating layer was partially peeled off or dropped off. In order to prevent such a phenomenon from occurring, in the present embodiment, the bond coat layer 2 having high heat resistance and having intermediate properties (particularly in ductility) between the substrate and the wear-resistant coating layer is provided. . Thereby, the adhesion of the wear-resistant coating is increased, and the durability can be greatly improved.

As the bond coat layer 2, it is preferable to use the same or similar material as the binder material of the wear-resistant coating layer 3. As the binder material of the wear-resistant coating layer 3, the aforementioned MCrAlY (where M is a metal) ), It is preferable to use the same material.

Preferably, the wear-resistant coating layer 3 comprises:
A Cr infiltration treatment is performed. As a method of the infiltration treatment, a powder method, a gas method, and a molten salt method can be used.

In the powder method, as shown in FIG. 3, a mixed powder obtained by adding 20 to 45% of alumina powder to Cr powder and a small amount of ammonium chloride as a reaction accelerator is put in a closed container together with a combustor part as an object to be treated. This method is carried out by heating at a temperature of 1000 ° C. or more in a reducing or neutral atmosphere.

In the gas method, as shown in FIG. 4, by heating to 500 to 1200 ° C. in an atmosphere of chromium chloride vapor containing hydrogen gas, chemically active fine metal chromium is deposited, and this is spray-coated. This is a method carried out by impregnating the resin.

As shown in FIG. 5, the molten salt method is a method in which an object to be treated is attached to a chromium chloride molten salt and chromium is directly permeated from a liquid phase. Usually, the treatment is performed by a powder method, but masking is performed on portions that do not require treatment to prevent the penetration of chromium.

By performing the above-described Cr infiltration treatment,
In the surface layer of the wear-resistant coating layer 3, the wear-resistant coating
The hard particles contained in the bonding layer 3 have a relatively low Cr content.
Low Cr carbide, Cr in this example_ThreeC_TwoIs the Cr content
Large Cr carbide, for example Cr ₇C_ThreeAnd Cr_{twenty three}C₆Transformed into
You. As the Cr content of Cr carbide increases,
Increased hardness, resulting in wear-resistant coatings
The hardness of the surface layer of the layer 3 is increased and the wear resistance is improved.
Can be.

In place of performing the Cr infiltration treatment,
An overcoat layer containing hard particles having a high Cr content such as Cr ₇ C ₃ or Cr ₂₃ C ₆ is used as a wear-resistant coating layer 3.
May be applied to the surface by high-speed gas flame spraying. In addition,
In this case, since the sprayed material is hard in this case, it is necessary to consider selection of a binder material and provision of a bond coat layer between the overcoat layer and the wear-resistant coating layer 3.

Further, changing the shape of the sprayed material from the conventional solid spherical shape as shown in FIG. 6A to a hollow shape as shown in FIG. 6B also improves the characteristics of the wear-resistant coating layer. It is suitable in making it. In this manner, the thermal spray material (powder) can be uniformly heated during thermal spraying, and the apparent density of the thermal spray particles is reduced, so that the acceleration of the thermal spray particles to a high velocity by the flame is enhanced. Therefore, thermal spraying at a high particle velocity becomes possible. In addition, handling properties during thermal spraying can be improved.

That is, when a large-diameter particle is sprayed by an ordinary spraying method, problems caused by the inability to uniformly heat the particle central portion and the inability to enhance the acceleration of the sprayed particles, for example, Problems such as a decrease in film strength and uneven film quality can be solved.

The application of such hollow particles is suitable as a coating material in terms of hardness and density, but it is difficult to apply Zr with large diameter particles.
Even when a material such as C, HfC, NbC, TaC, WC, and Mo ₂ C is used as the hard particles of the wear-resistant coating layer, thermal spraying can be performed. Such a material is Cr ₃ C ₂
Since the hardness is higher, improvement of the wear resistance of the wear-resistant coating layer can be expected.

In high-speed gas flame spraying of an abrasion-resistant coating, the hardness of the sprayed material is important as an indicator of abrasion resistance. The second important factor is the density. Does not provide sufficient adhesion even if
In addition, defects such as pores are likely to occur. Table 1 below shows this 2
This is a table of coating materials prepared in consideration of the following factors, and the method according to the present invention makes it possible to easily perform thermal spraying with large-diameter particles.

[0042]

[Table 1] It is not necessary to completely hollow the particles, and it is not necessary to use a mechanical or inert gas such as argon at the stage of particle formation, for example, as shown in FIG. A hollow shape is sufficient.

The results of a wear test simulating combustion vibration of a combustor performed to confirm the effects of the present invention will be described below. As shown in FIG. 8, the abrasion test was performed by generating a micro vibration between two materials to which a constant pressure was applied so as to obtain a constant surface pressure and measuring the loss of the materials.

As a sample, (1) 75% Cr ₃ C ₂ +25
With a wear-resistant coating of the composition of
(2) 93% Cr ₃ C ₂ + 7% NiCr with a wear-resistant coating composition; (3) 75% Cr ₃ C ₂ +25
% NiCrAlYCo with a wear-resistant coating, and (4) a wear-resistant coating with a composition of 75% Cr ₃ C ₂ + 25% NiCr and further subjected to a Cr infiltration treatment. Figure 8 for each
The abrasion test was performed by the method shown in FIG. The test temperature is (1)
(2) (4) is 600 ° C, and (3) is 700 ° C. (1) is a conventional wear-resistant coating,
(2), (3), and (4) have the features of the present invention one by one.

FIG. 9 shows the result. As can be understood from FIG. 9, the wear resistance is improved by setting the content of Cr ₃ C ₂ to 93% as compared with the conventional 75% Cr ₃ C ₂ coating. Further, it can be seen that the wear resistance is improved by using CoNiCrAlY as the binder material. Further, it can be seen that when the Cr infiltration treatment is performed, the wear resistance is improved.

The wear-resistant surface treatment according to the present invention can be applied to the gas turbine wheel bolted as shown in FIG. 9 in addition to the parts related to the combustor described with reference to FIGS. (A hatched portion in a region surrounded by a circle in FIG. 9) can be suitably applied.

Further, the shroud segment, in which the tip of the moving blade shown in FIG. 10 moves closest, may greatly lose material due to the contact when it comes into contact with the moving blade due to a difference in thermal expansion. By applying the coating according to the present invention to the hatched portion in the area circled in FIG. 10, the thickness loss can be minimized even in the case of contact.

The wear-resistant surface treatment according to the present invention can be applied not only to the above-mentioned application parts but also to various other parts of a gas turbine component where wear is a problem, and it is possible to greatly improve the durability. it can.

[0049]

According to the present invention, the life of gas turbine components can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a configuration of a wear-resistant surface treatment according to the present invention.

FIG. 2 is a view for explaining the construction of a wear-resistant coating layer.

FIG. 3 is a view for explaining a Cr infiltration treatment by a powder method.

FIG. 4 is a view for explaining a Cr infiltration treatment by a gas method.

FIG. 5 is a view for explaining Cr infiltration treatment by a molten salt method.

FIG. 6 is a diagram illustrating the shape of spray particles.

FIG. 7 is a diagram illustrating a wear test method.

FIG. 8 is a graph illustrating test results of a wear test.

FIG. 9 is a diagram showing a wheel fitting portion of the gas turbine.

FIG. 10 is a diagram showing a shroud segment of the gas turbine.

FIG. 11 is a diagram illustrating a main part of the gas turbine.

FIG. 12 is a diagram illustrating a combustor of a gas turbine and its related components.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) C23C 10/10 C23C 10/10 10/24 10/24 10/38 10/38 (72) Inventor Ikeda Kazuaki 2-4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Toshiba Keihin Works (reference) 4K031 AA02 AB03 AB04 AB08 CB14 CB17 CB19 CB22 CB45 FA05

Claims (10)

[Claims] 1. A gas turbine component which has been subjected to a wear-resistant surface treatment, comprising: a base material; and a wear-resistant coating layer formed on the base material by a thermal spraying method. A gas turbine, comprising: hard particles such as Cr carbide; and a binder for bonding the hard particles to each other, wherein the content of the binder contained in the wear-resistant coating layer is 25 wt% or less. parts. 2. A gas turbine component having a wear-resistant surface treatment, comprising: a base material; and a wear-resistant coating layer formed on the base material by a thermal spraying method. It comprises hard particles such as Cr carbide and a binder for bonding the hard particles to each other. As the material of the binder, CoNiCrAlY, N
MCrAlY of iCoCrAlY or CoCrAlY
(Where M is a metal). 3. The hard particles contained in the wear-resistant coating layer are made of at least one carbide selected from the group consisting of ZrC, HfC, NbC, TaC, WC and Mo ₂ C. The gas turbine component according to claim 1. 4. A gas turbine component which has been subjected to a wear-resistant surface treatment, comprising: a base material; and a wear-resistant coating layer formed on the base material by a thermal spraying method. It comprises a hard particle made of Cr carbide and a binder for bonding the hard particles to each other, wherein the Cr content in the surface layer of the wear-resistant coating layer is larger than the Cr content in the inside. Parts for gas turbines. 5. The wear-resistant coating layer is subjected to a Cr infiltration treatment, whereby the Cr content in the surface layer of the wear-resistant coating layer is larger than the Cr content in the inside. The gas turbine component according to claim 4, wherein 6. The method according to claim 1, wherein the Cr infiltration treatment comprises heating a powder containing Cr by bringing the powder into contact with the wear-resistant coating layer.
A method of contacting the wear-resistant coating layer with a heating steam containing Cr;
6. The gas turbine component according to claim 5, wherein the component is immersed in a molten salt containing r. 7. The anti-wear coating layer according to claim 1, wherein the first anti-wear coating layer comprises
And a second upper coating, wherein the first and second coatings comprise hard particles made of Cr carbide and a binder for bonding the hard particles to each other; The Cr content of the Cr carbide contained in the coating is determined by the C content contained in the underlying first coating.
The gas turbine component according to claim 4, wherein the Cr content of the r carbide is greater than the Cr content. 8. The gas turbine according to claim 1, wherein a material powder having a hollow or quasi-hollow shape is used when spraying the wear-resistant coating layer. parts. 9. The gas turbine component according to claim 1, wherein a bond coat layer is provided between the wear-resistant coating layer and the substrate. 10. A gas turbine comprising the gas turbine component according to claim 1.