WO2012029540A1

WO2012029540A1 - Heat-masking coating film, process for production thereof, and heat-resistant alloy members using the same

Info

Publication number: WO2012029540A1
Application number: PCT/JP2011/068592
Authority: WO
Inventors: 岳志泉
Original assignee: 株式会社日立製作所
Priority date: 2010-09-03
Filing date: 2011-08-17
Publication date: 2012-03-08
Also published as: JP2012052206A

Abstract

A heat-masking coating film which is easier to produce than in the prior art and has superior durability to the prior art, a process for production thereof, and heat-resistant alloy members using the same are offered. A heat-masking coating film (10) formed on a base material (3) can be offered wherein the heat-masking coating film can be produced more easily than in the prior art and has superior durability to the prior art by having a bonding coat (1) which includes a plurality of metal particles from a metal (11), formed such that the plurality of metal particles (11) are joined in a continuum via an oxide of the metal (metal oxide) (11a), and an oxide layer (2) which includes an oxide of the metal; a process for production thereof, and heat-resistant alloy members using the same can also be offered. Figure 1

Description

Heat shielding coating film, manufacturing method thereof, and heat-resistant alloy member using the same

The present invention relates to a heat shielding coating film, a method for producing the same, and a heat-resistant alloy member using the same.

In gas turbines, the temperature of combustion gas (for example, the temperature of gas generated by burning fuel or the like) is increasing with the aim of increasing its efficiency. At present, the temperature of the combustion gas that is normally used has already exceeded the melting point of the base material of heat-resistant alloy members such as turbine blades and stationary blades, and various cooling techniques are employed. Furthermore, recently, it has been widely practiced to form a thermal barrier coating (TBC) film, which is usually composed of a top coat and a bond coat, on members constituting the gas turbine. This is because by providing the TBC film, the effect of suppressing the heat flow from the combustion gas to the member and reducing the member temperature is obtained.

In the TBC film formation technology, the top coat contains an oxide having low thermal conductivity. As a specific example of such an oxide, yttria partially stabilized zirconia (Ytria: YSZ) whose crystal structure is stabilized by addition of yttria can be given.

For the bond coat, from the viewpoint of ensuring oxidation resistance and corrosion resistance, for example, MCrAlY alloy (M represents one or more atoms selected from the group consisting of iron, nickel and cobalt), Ni—. Aluminides such as Al and Ni—Al—Pt are contained. In the bond coat, in the vicinity of the interface between the bond coat and the top coat, a thermally grown oxide (TGO) is usually formed. By forming TGO, the top coat and the bond coat can be brought into close contact with each other with the effect of protecting the substrate from oxidizing and corrosive environments. As TGO, aluminum oxide having a low growth rate and excellent environmental blocking ability is suitable. Therefore, in order to easily form aluminum oxide in the bond coat, the bond coat has a higher aluminum concentration than the base material. There are many cases.

Recent TBC films are known to have a heat shielding effect of about 150 ° C. However, the TBC film is exposed to a high temperature during gas turbine operation, but drops to room temperature when stopped. Therefore, there is a problem that the thermal stress change due to heating and cooling in the bond coat is large and the top coat may peel off. It was. Such peeling is considered to be due to TGO formed at the interface between the bond coat and the top coat and cracks in the top coat caused by the difference in thermal expansion coefficient between the bond coat and the top coat. .

In order to solve such problems, Patent Document 1 describes a thermal barrier coating layer having a multilayer structure in which a plurality of intermediate layers are stacked in addition to a bond coat and a top coat. A technique is described in which the intermediate layer is formed by mixing MCrAlY and columnar aluminum oxide having a controlled aspect ratio, and the amount of the mixture is changed in an inclined manner. Patent Document 2 discloses a metal in which a thermal barrier coating layer provided on a metal substrate has an intermediate layer, and the intermediate layer is provided as a diaphragm and continuous between the particulate ceramic phase and the ceramic phase. Techniques that consist of phases are described.

JP 2001-279418 A JP 2003-266588 A

For film formation of TBC in an industrial gas turbine member, productivity and workability are desired, and a spraying method is generally used. However, in the technique described in Patent Document 1, a multilayer structure and a gradient composition are used. Therefore, there is a problem that the thermal spraying process becomes complicated.

Furthermore, in the technique described in Patent Document 2, although there is a certain effect on durability, a step of coating the metal phase on the particulate ceramic phase is necessary, and the metal phase is platinum (Pt) having corrosion resistance. Noble metals such as iridium (Ir) are preferable, and there is a problem that costs increase.

The present invention has been made to solve the above-mentioned problems, and its object is to provide a heat-shielding coating film that can be easily manufactured and has superior durability compared to the prior art, a method for manufacturing the same, and heat resistance using the same. An object is to provide an alloy member.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by adopting a bond coat having an oxide skeleton structure as the bond coat of the TBC film, and completed the present invention. It was.

According to the present invention, it is possible to provide a heat-shielding coating film that can be easily manufactured and is more durable than the conventional one, a manufacturing method thereof, and a heat-resistant alloy member using the same.

It is the figure which showed typically a part of cross section of the structure by which the heat shielding coating film which concerns on one (1st embodiment) of this embodiment was formed on the base material. It is a graph which shows the peeling cycle test result of Example 1 and Comparative Example 1. It is a drawing substitute photograph which image | photographed the partial cross section after the heat cycle test of the heat shielding coating film manufactured in Example 1 with the scanning electron microscope. It is a drawing substitute photograph which image | photographed the partial cross section after the heat cycle test of the heat shielding coating film manufactured in the comparative example 1 with the scanning electron microscope.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment” as appropriate) will be described in detail, but the present embodiment is not limited to the following contents and does not depart from the gist thereof. Any change can be made within the range.

[1. Thermal shielding coating film 10]
The heat-shielding coating film 10 according to the present embodiment is a heat-shielding coating film formed on a substrate, and includes a plurality of metal particles made of metal, and the metal oxide is continuous between the plurality of metal particles. A bond coat 1 having an oxide (that is, metal oxide) skeleton structure formed by bonding and a top coat 4 containing a metal oxide.

[1-1. Bond coat 1 having oxide skeleton structure]
The bond coat 1 having an oxide skeleton structure included in the heat-shielding coating film 10 according to the present embodiment (hereinafter, referred to as “bond bond 1 according to the present embodiment” as appropriate) includes a plurality of metal particles made of metal. The oxide of the metal is continuously joined between the plurality of metal particles. FIG. 1 is an enlarged view schematically showing a part of a cross section of the bond coat 1 having an oxide skeleton structure in the heat shielding coating film 10 according to the present embodiment. In FIG. 1, metal particles 11 are deposited to form a bond coat 1 having an oxide skeleton structure, and the metal particles 11 in the bond coat 1 having an oxide skeleton structure are represented by bold lines. A metal oxide 11a is formed.
In addition, in addition to what consists of only one type of metal atom in this embodiment, the alloy and superalloy etc. which two or more types of metal atoms consist of arbitrary ratios and combinations shall be included.

The bond coat 1 according to the present embodiment has a function of protecting the base material (usually including metal) on which the heat shielding coating film 10 is formed from being corroded and oxidized. Furthermore, the bond coat 1 according to this embodiment also functions as a base for ensuring the adhesion of the top coat 4 that is normally provided on the bond coat 1.

Any metal can be used as the metal constituting the metal particles 11 deposited on the bond coat 1 having an oxide skeleton structure as long as the effects of the present invention are not significantly impaired. Those exhibiting corrosion resistance and oxidation resistance are preferably used. Specifically, for example, a metal (alloy) containing aluminum (Al) and further containing at least one atom selected from the group consisting of nickel (Ni), chromium (Cr), and cobalt (Co) is preferable. Among them, a metal represented by the following formula (1) is preferable.
MCrAlY (1)
(However, M represents one or more atoms selected from the group consisting of iron (Fe), nickel, and cobalt.)

Specific examples of the metal represented by the above formula (1) include CoNiCrAlY (specific composition by weight fraction such as Co-32Ni-21Cr-8Al-0.5Y), NiCoCrAlY (specific As a composition formula by weight fraction, Ni-17Cr-23Co-12.5Al-0.5Y etc.) can be mentioned. In addition, a metal may be used individually by 1 type and may use 2 or more types by arbitrary ratios and combinations.

The shape of the metal particles 11 continuously deposited on the bond coat 1 according to the present embodiment is arbitrary as long as the effects of the present invention are not significantly impaired. By spraying, the shape is usually flat, elliptical or the like.
Here, in this embodiment, “the metal oxide is formed by continuously joining” means that all metal oxides (that is, a network-like shape as shown in FIG. The metal oxides 11a) are connected to each other at at least one point to form an integral network (that is, continuously joined). However, in the present embodiment, it is preferable that the metal particles 11 are bonded to other adjacent metal particles 11 by at least one metal bond. With such a configuration, the heat shielding coating layer according to the present embodiment can be made stronger.

In the bond coat 1 according to the present embodiment, the metal particles 11 are deposited as described above, and further, the metal oxide 11a is continuously joined. However, most of the metal oxides 11a are formed by continuously joining only in the direction parallel to the interface of the bond coat 1 having an oxide skeleton structure (that is, in the horizontal direction in FIG. 1). In this case, that is, when it is not so continuous in the vertical direction (that is, the vertical direction in FIG. 1), the metal oxide 11a formed between the metal particles 11 is cracked and has an oxide skeleton structure. The bond coat 1 may be peeled off. Therefore, it is preferable that the metal oxide 11a is uniformly joined not only in the direction parallel to the interface of the bond coat 1 having the oxide skeleton structure but also in the direction perpendicular to the interface. Specifically, in the cross section of the bond coat 1 having an oxide skeleton structure, the total cross sectional area of the metal oxide 11a is usually 1% with respect to the total cross sectional area of the bond coat 1 having an oxide skeleton structure. In addition, the upper limit is usually 40% or less, preferably 15% or less, and more preferably 10% or less. When the area ratio of the metal oxide 11a is within the above range, the metal oxide 11a is continuously joined in a more appropriate form not only in the parallel direction but also in the vertical direction. Can do.

The calculation of each area can be performed based on the following method. First, for example, using a scanning electron micrograph (hereinafter, referred to as “SEM” as appropriate), the oxide skeleton structure at an arbitrary magnification that can identify the structure of the bond coat 1 having the oxide skeleton structure. A cross section of the bond coat 1 having In the bond coat 1 having a photographed oxide skeleton structure, the metal particles 11 and the metal oxide 11a are photographed with different shades due to the difference in their components. 11a can be distinguished. Then, for example, the amount (area) of the metal oxide 11a contained in the bond coat 1 having an oxide skeleton structure is calculated using image analysis software or the like using the difference in density, and the oxide skeleton structure is obtained. The ratio (area ratio) of the metal oxide 11a contained in the bond coat 1 can be calculated.

In this embodiment, the thickness W and the shortest distance D of a metal oxide described later are determined based on a photograph taken by SEM. The reason is that the metal particles 11 are deposited in a complex manner in the bond coat 1 having an oxide skeleton structure, and the metal oxide 11a is formed when the metal particles 11 are adjacent to each other. This is because the region of oxide 11a, the formation range, the thickness of the layer made of metal oxide 11a, the shape thereof, and the like cannot be clearly defined. Therefore, in the present embodiment, the metal oxide 11a to be formed is defined in two dimensions instead of three dimensions, and the definition of the present embodiment is performed using a representative SEM as an observation means in the definition. is there.

As described above, the metal oxide 11a is formed between the metal particles 11 included in the bond coat 1 having an oxide skeleton structure. Therefore, in the cross section of the bond coat 1 having an oxide skeleton structure, at least two metal oxides 11a are present on the outer periphery of the metal particles 11, and the two metal oxides 11a The shortest distance is usually 5 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and the upper limit is usually 100 μm or less, preferably 75 μm or less, more preferably 60 μm or less. When the shortest distance is too shorter than the above range, it may be difficult to manufacture the heat shielding coating film 10, and when the shortest distance is too long than the above range, the bond coat 1 having an oxide skeleton structure. There is a possibility that the strength of can not be maintained. Note that the shortest distance can usually be controlled by the thermal spraying conditions of the metal particles 11 when the bond coat 1 having an oxide skeleton structure is formed. The shortest distance can be measured using an SEM and corresponds to “D” in FIGS. 1, 3 and 4 (FIGS. 3 and 4 will be described later).

In the bond coat 1 having an oxide skeleton structure according to the present embodiment, a plurality of metal particles 11 are deposited, and a metal oxide 11 a is formed along the plurality of deposited metal particles 11. The metal oxide 11 a formed along the metal particles 11 is usually an oxide of a metal that is particularly easily oxidized (that is, particularly highly reactive) among all the metals contained in the metal. For example, when the metal constituting the metal particle 11 is represented by the above formula (1), the metal oxide 11a formed between the plurality of metal particles 11 is usually aluminum oxide. *

However, the metal oxide 11a formed between the metal particles 11 is not necessarily all aluminum oxide, but 90% by weight or more of the metal oxide 11a formed between the metal particles 11 is aluminum oxide. It is preferable. When 90% by weight or more is aluminum oxide, the oxidation resistance and corrosion resistance of the base material 3 (shown in FIG. 1) on which the heat shielding coating film 10 according to this embodiment is formed are more reliable. It will be a thing. The amount of aluminum oxide contained in the metal oxide 11a formed between the metal particles 11 can be measured by, for example, a wavelength dispersive X-ray spectrometer.

Therefore, the metal in the bond coat 1 according to the present embodiment includes at least aluminum and at least one metal selected from the group consisting of nickel, chromium, and cobalt, and aluminum oxide included in the oxide of the metal. The amount of is preferably 90% by weight or more based on the total amount of the metal oxide.

In the cross section of the bond coat 1 according to the present embodiment, the thickness (width) of the metal oxide 11a is usually 0.1 μm or more, preferably 0 after exposure at an arbitrary temperature and time after film formation. 0.5 μm or more, more preferably 1 μm or more, and the upper limit is usually 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less. When the metal oxide 11a is too thin, the strength of the bond coat 1 having an oxide skeleton structure may be insufficient. When the metal oxide 11a is too thick, cracks are generated inside the formed metal oxide 11a, There is a possibility that the bond coat 1 having an oxide skeleton structure peels from the crack. Note that the thickness of the metal oxide can be measured using, for example, the SEM, and corresponds to “W” in FIGS. 1, 3, and 4. In addition, the thicknesses of the metal oxides 11a included in the bond coat 1 having the oxide skeleton structure according to the present embodiment may not all be the same. It is preferable to be included in the range.

The thickness of the bond coat 1 according to this embodiment is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 50 μm or more, preferably 100 μm or more, more preferably 125 μm or more, and its upper limit is usually 400 μm. Hereinafter, it is preferably 350 μm or less, more preferably 300 μm or less. When the bond coat 1 having an oxide skeleton structure is too thin, protection against corrosion and oxidation may be insufficient, and when it is too thick, peeling may occur. The thickness of the bond coat 1 having an oxide skeleton structure can be measured using, for example, the SEM. In addition, the thickness of the bond coat 1 according to the present embodiment may not all be the same, but even in that case, it is preferable that the thickness of all the portions is included in the above range.

Further, the bond coat 1 according to the present embodiment may contain any component other than the metal and the metal oxide as long as the effects of the present invention are not significantly impaired. Optional components that may be included include, for example, alkaline earth elements such as magnesium, nonmetallic elements such as silicon and germanium, active elements such as hafnium, rare earth elements such as lanthanum and cerium, platinum, iridium, palladium and the like Examples include platinum group elements. Arbitrary components may be contained individually by 1 type, and 2 or more types may be contained by arbitrary ratios and combinations.

Further, when the bond coat 1 according to the present embodiment includes an arbitrary component, the content thereof is preferably 0.1 wt% or more and 5 wt% for an alkaline earth element such as magnesium and a nonmetallic element such as silicon. Hereinafter, the active element such as hafnium and the rare earth element such as lanthanum are preferably 0.01% by weight to 3% by weight, and the platinum group element such as platinum is preferably 0.1% by weight to 15% by weight. is there. If the amount of any component is too large, the melting point and mechanical properties of the metal particles 11 change, and the bond coat 1 having an oxide skeleton structure may be insufficient in strength.

[1-2. Thermally grown oxide layer 2]
When the heat shielding coating film 10 according to the present embodiment is exposed to high temperature in an oxidizing atmosphere at an arbitrary temperature, time, a thermally grown oxide layer 2 (forms on the bond coat 1 having the oxide skeleton structure. To do.

Further, the thermally grown oxide layer 2 is formed according to [1-1. Since the metal oxide (that is, the metal oxide 11a) described in the bond coat 1 having an oxide skeleton structure is included, the description thereof is omitted.

[1-3. Base material 3]
The base material 3 is formed with the heat shielding coating film 10 according to the present embodiment on the surface thereof. The type, material, and the like of the base material 3 are arbitrary as long as the effects of the present invention are not significantly impaired, but are usually metals. However, from the viewpoint of improving the heat resistance of the base material 3 by the heat shielding coating film 10, the material constituting the base material 3 is preferably one in which the base material 3 itself has a certain degree of heat resistance. It is preferable to use a material excellent in creep strength and fatigue strength at high temperature. Specific examples of such materials include Ni-based superalloys such as IN738 (Ni-16Cr-8.5Co-1.7Mo-2.6W-0.9Nb-3.4Ti-3.4Al wt%), A Co-base superalloy such as FSX414 (Co-10Ni-28Cr-7W-1Fe) can be preferably used. The “superalloy” is a technical term representing an alloy having excellent strength at high temperature, oxidation resistance, corrosion resistance, ductility, and the like. For example, a Ni-base superalloy is particularly excellent in creep strength and fatigue strength, and a Co-base superalloy is particularly excellent in corrosion resistance and ductility.

Among these, when a heat-resistant alloy member manufactured by forming the heat shielding coating film 10 according to the present embodiment on the base material 3 is used as, for example, a moving blade of a gas turbine, the base material is further excellent in strength. Unidirectionally solidified or single crystal Ni-base superalloy is preferably used. Since these materials have a stable microstructure of γ-Ni and γ'-Ni3Al, high strength can be expressed.

[1-4. Other layers]
As long as the heat shielding coating film 10 according to the present embodiment is formed on the substrate 3 and has the bond coat 1 according to the present embodiment, other layer configurations, materials, and the like remarkably exert the effects of the present invention. It is optional as long as it is not impaired. However, it is preferable that the heat shielding coating film 10 according to the present embodiment is formed on the base material 3 made of, for example, an alloy or a superalloy, and the top coat 4 is provided.

By providing the top coat 4 on the bond coat 1 having the oxide skeleton structure, the heat-resistant alloy member 100 made of the base material 3 on which the heat shielding coating film 10 according to the present embodiment is formed is converted into, for example, a high-temperature gas. When exposed, a temperature gradient is generated between the gas and the base material 3, and the temperature rise of the base material can be efficiently suppressed.

The material constituting the top coat 4 is arbitrary as long as the effects of the present invention are not significantly impaired, but those having low thermal conductivity are preferable. Specific examples of such a material include yttria stabilized zirconia (YSZ; composition formula: ZrO ₂ -6Y ₂ O ₃ , ZrO ₂ -7Y ₂ O ₃ or ZrO ₂ -8Y ₂ O ₃ ).

The structure of the top coat 4 is arbitrary as long as the effects of the present invention are not significantly impaired, and examples thereof include a structure including porous, columnar, and vertical cracks.

The thickness of the top coat 4 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 100 μm or more, preferably 150 μm or more, more preferably 200 μm or more, and the upper limit is usually 1000 μm or less, preferably 750 μm. Hereinafter, it is more preferably 500 μm or less. If the top coat 4 is too thin, the heat shielding effect may be insufficient, and if it is too thick, peeling may be likely to occur. The thickness of the top coat 4 can be measured using, for example, the SEM. Moreover, although the thickness of the topcoat 4 which concerns on this embodiment may not become the same thickness in all the parts, even in that case, it is preferable that the thickness in all the parts is contained in the said range.

Further, the top coat 4 may contain an arbitrary component as long as the effects of the present invention are not significantly impaired. Examples of optional components that may be included include rare earth element oxides such as ceria and gadolinia. Arbitrary components may be contained individually by 1 type, and 2 or more types may be contained by arbitrary ratios and combinations.

Further, when the top coat 4 includes an optional component, the content thereof is arbitrary as long as the effects of the present invention are not significantly impaired. However, when the amount of the optional component is too small, or conversely, the top coat 4 The crystal structure of the coat 4 becomes unstable. Moreover, there is a possibility that the crystal structure easily changes due to a temperature change, and peeling easily occurs due to a volume change associated therewith.

Further, as an optional layer that the heat-shielding coating film 10 according to this embodiment may have, in addition to the top coat 4, another surface layer may be provided unless the effects of the present invention are significantly impaired. May be.

[2. Manufacturing method of heat shielding coating film 10]
The heat shielding coating film 10 according to the present embodiment can be manufactured by any method. However, from the viewpoint of the ease of the manufacturing method, the manufacturing method of the heat shielding coating film 10 according to the present embodiment preferably includes a step of depositing the metal particles 11 by a thermal spraying method. Hereinafter, the manufacturing method of the heat-resistant alloy member 100 (hereinafter, appropriately referred to as “heat-resistant alloy member 100 according to the present embodiment”) on which the heat-shielding coating film 10 according to the present embodiment is formed as shown in FIG. The method for manufacturing the heat-shielding coating film 10 according to the present embodiment will be specifically described below, but what is described below is merely an example of the method for manufacturing the heat-shielding coating film 10 according to the present embodiment, The method is not limited to the contents described below.

FIG. 1 schematically shows a part of a cross section of a heat-resistant alloy member in which a heat shielding coating film 10 according to the present embodiment is formed on a base material. A heat-resistant alloy member 100 formed with a heat shielding coating film 10 according to the present embodiment shown in FIG. 1 includes a bond coat 1 having an oxide skeleton structure in which metal particles 11 are deposited on a substrate 3, and a top. The coat 4 is laminated in this order.

The heat-resistant alloy member 100 according to this embodiment can be manufactured mainly through the following steps. (1) A pretreatment is performed on the surface of the substrate 3 (pretreatment step).
(2) The metal particles 11 are deposited on the pretreated substrate 3 (bond coat deposition step). (3) A top coat 4 is formed on the bond coat 1 having a deposited oxide skeleton structure (top coat forming step).
Hereinafter, each process will be described.

[Pretreatment process]
In the manufacturing method of the heat-resistant alloy member 100 according to the present embodiment, it is preferable to first perform a pretreatment step in which processing for roughening the surface is performed on the portion of the base material 3 that is in close contact with the bond coat 1. . As a specific method of surface processing, any method can be applied as long as the effects of the present invention are not significantly impaired, but the viewpoint of ensuring good adhesion between the substrate 3 and the bond coat 1 having an oxide skeleton structure. Therefore, it is preferable to perform blasting on the surface of the base material 3. In the blasting process, for example, non-metallic or metallic particles are sprayed on the surface of the substrate 3 at a high speed. By this treatment, the surface of the base material 3 is roughened, and impurities such as oil can be removed from the surface of the base material 3 to clean the surface. Thereby, better adhesion of the bond coat 1 having an oxide skeleton structure to the substrate 3 can be ensured.

The type of metal or non-metallic particles used for the blast treatment is arbitrary as long as the effects of the present invention are not significantly impaired, but examples thereof include non-metallic particles such as silica sand, alumina and silica, aluminum, zinc, copper, steel shot and the like. Metal particles can be used. In addition, these particles may be used individually by 1 type, and may use 2 or more types by arbitrary ratios and combinations.

The size of the particles is arbitrary as long as the effects of the present invention are not significantly impaired. However, when the particles are too small, roughening may be insufficient and the adhesion may be insufficient. 3 The unevenness of the surface becomes too large, and the thickness of the metal particles 11 to be deposited may be uneven.

As a device for performing blasting, for example, a projection device using compressor air can be used. For example, this apparatus can be used to perform blasting on the surface of the substrate 3. The conditions for performing the blast treatment are arbitrary as long as the effects of the present invention are not significantly impaired. For example, the particle projection pressure can be 0.1 MPa or more and 0.8 MPa or less.

[Bond coat deposition process]
Next, a step of depositing the metal particles 11 is performed on the surface of the base material 3 subjected to the blast treatment. As a specific deposition method, for example, a low pressure plasma spraying (LPPS), a high velocity flame spraying (High Velocity Oxy-fuel Frame-spraying: HVOF), or the like is used. Can be deposited on top.

As shown in FIG. 1, it includes a plurality of metal particles 11 made of metal, and has a network-like shape in which the metal oxide (metal oxide 11 a) is continuously joined between the metal particles 11. The thermal spraying conditions for forming the bond coat 1 having an oxide skeleton structure are arbitrary as long as the effects of the present invention are not significantly impaired. However, the temperature and the particle velocity of the metal particles 11 during thermal spraying may satisfy the following conditions. Of particular importance.

In order for the metal oxide 11a to be present in a continuously bonded form, the metal particles 11 are deposited on the substrate 3 while being covered with an extremely thin metal oxide 11a film during the flight to the substrate 3. It is particularly important. When the temperature of the metal particle 11 is high and the metal particle 11 flies while melting, the film of the metal oxide 11a gathers at a specific portion of the molten metal particle 11, and the metal oxide 11a continuously joins after deposition. It is not a structure. Conversely, when the temperature of the metal particles 11 is low, the metal particles 11 do not accumulate, and the bond coat 1 having an oxide skeleton structure cannot be formed.

It is particularly important that the metal oxide 11a has a preferable shape such as a flat shape and an ellipse after being deposited. When the speed of the metal particles 11 is high, the metal particles 11 after deposition are excessively flat, and most of the metal oxides 11a are only in a direction parallel to the interface of the bond coat 1 having an oxide skeleton structure. When formed continuously and not so continuously in the vertical direction, a preferred oxide skeleton cannot be formed. When the speed of the metal particles 11 is low, the metal particles 11 do not accumulate.

The conditions of the temperature and particle velocity of these metal particles 11 vary depending on the composition of the powder, the particle size, and the thermal spraying apparatus used. For example, in the case of using HVOF, the particle size distribution of the metal particles 11 is usually 20 μm or less, preferably 15% or less, more preferably 10% or less, and 90 μm or more is usually 10% or less, preferably 45 μm or less. Is 5% or less, more preferably 3% or less. However, the above-mentioned spraying conditions can be implemented by those skilled in the art by modifying the control conditions of the spraying apparatus owned.

[Topcoat formation process]
A top coat 4 is formed on the bond coat 1 having the skeleton structure of the formed oxide. Although the formation method of the topcoat 4 is arbitrary as long as the effect of this invention is not impaired remarkably, for example, an atmospheric pressure plasma spraying (APS) can be used under atmospheric pressure.

As described above, the heat shielding coating film 10 according to this embodiment can be manufactured.

When the heat shielding coating film 10 manufactured through the above steps is exposed to a high temperature in an oxidizing atmosphere at an arbitrary temperature, time, and the metal oxide 11a is bonded to the bond coat 1 having an oxide skeleton structure. Growing to form a thermally grown oxide layer 2 on the surface.

The mechanism by which the oxide skeleton structure and the thermally grown oxide layer 2 grow on the bond coat 1 having the oxide skeleton structure in the above high temperature exposure process will be described. The top coat 4 usually has voids (that is, pores) through which oxygen can permeate. Then, oxygen existing around the member passes through the pores and permeates the top coat 4 to reach the bond coat 1 having an oxide skeleton structure. Then, the reached oxygen reacts with a particularly easily oxidized metal (for example, aluminum) contained in the metal particles 11 at the interface between the bond coat 1 and the top coat 4 having an oxide skeleton structure, and the metal oxide. A layer consisting of is formed. The layer made of the metal oxide thus formed is the thermally grown oxide layer 2.

A normally desired dense bond coat in which the metal particles 11 are bonded to each other by metal bonds does not form a form in which the metal oxides 11a are continuously joined. The reason is that a thermally grown oxide layer 2 that hardly permeates oxygen grows along the uppermost surface of the metal particle 11 existing at the uppermost part of the metal particles 11, and the metal particles 11 are dense and oxygen bonds. This is because it does not enter the inside of the coat.

On the other hand, in the bond coat 1 according to the present embodiment, the reached oxygen is not only the thermally grown oxide layer 2 but also the metal oxide 11a existing between the metal particles 11 in which oxygen easily penetrates or continuously joined. The metal oxide 11a further grows due to the invading oxygen, and forms a strong heat shielding coating film 10.

In addition, when using the member which has the heat shielding coating film 10 which concerns on this embodiment, since the use temperature is normal high temperature, as long as it uses in the environment where oxygen exists, the said metal oxide 11a and thermal growth oxide Layer 2 continues to grow. However, the amount of oxygen that permeates through the top coat 4 and the thermally grown oxide layer 2 is extremely small, and the reaction of oxygen and metal reacting to form the metal oxide 11a and the thermally grown oxide layer 2 is very slow. For this reason, such a response is sufficiently negligible in the short term.

[3. Application of heat shielding coating film 10 according to this embodiment]
The heat shielding coating film 10 according to the present embodiment can be used for any application. For example, the heat-resistant alloy member 100 can be manufactured by forming the heat shielding coating 10 according to the present embodiment on the base material 3 containing a metal. As such a heat-resistant alloy member 100, heat resistance and durability are usually required, and for example, a moving blade, a stationary blade, a combustor, etc. of a gas turbine are preferable.

Hereinafter, the present embodiment will be described in more detail with reference to examples. However, the present embodiment is not limited to the following examples, and may be arbitrarily modified without departing from the scope of the present invention. Can do.

In the following examples, the heat-resistant alloy member 100 shown in FIG. 1 was manufactured. A specific manufacturing method is as follows.
A Ni-based alloy IN738 (Ni-16Cr-8.5Co-1.7Mo-2.6W-0.9Nb-3.4Ti-3.4Al), which is preferably used as a moving blade of a gas turbine, is cast into a rod shape to form a shaft. By cutting in a direction perpendicular to the direction, a coin-shaped alloy member having a diameter of 2.5 cm and a thickness of 3 mm was produced. Then, using an air blast machine, the aluminum oxide particles having a particle size of 24 were subjected to a blasting process on the surface of the alloy member at a projection pressure of 0.5 MPa. And what was blasted was used as the base material 3 in Example 1 and Comparative Example 1 below.

Example 1
CoNiCrAlY (composition formula by weight fraction: Co-32Ni-21Cr-8Al-0.5Y, nominal particle size range: 45 to 75 μm) was used as the metal particles 11 and HVOF (Woka star 600 manufactured by Sulzer Metco Co., Ltd.) Metal particles 11 were deposited on the surface of the substrate 3 to form a bond coat 1 having a thickness of about 160 μm at the thickest part and about 100 μm at the thinnest part. As the HVOF conditions, the distance between the thermal spraying apparatus and the base material 3 at the time of thermal spraying is 300 mm, the spraying powder supply rate is 60 g / min, the oxygen supply rate is 900 l / min, and the kerosene supply rate is 3.9 l / min. .

Yttria-stabilized zirconia (composition formula by weight fraction: ZrO ₂ -8Y ₂ O ₃ , nominal particle size range: 11 to 125 μm) with respect to the base material 3 on which the bond coat 1 having the oxide skeleton structure is formed. ) Was used to form a topcoat 4 with an APS (9 MB manufactured by Sulzer Metco) so that the thickest part was 380 μm and the thinnest part was 320 μm. As the APS conditions, the distance between the thermal spraying apparatus and the substrate 3 during thermal spraying was 90 mm, the amount of sprayed powder supplied was 30 g / min, and the current value was 900 A.

(Comparative Example 1)
The metal particles 11 are deposited using a vacuum spraying apparatus in which the environmental pressure during decompression is 6.6 kPa, and the metal particles 11 are CoNiCrAlY (composition formula by weight fraction: Co-32Ni-21Cr-8Al-0.5Y). Nominal particle size range: 5 to 37 μm) and the thickest part was 140 μm and the thinnest part was 100 μm. As the conditions for thermal spraying, the top was the same as in Example 1 except that the distance between the thermal spraying apparatus and the substrate 3 during thermal spraying was 300 mm, the supply amount of thermal spray powder was 30 g / min, and the current value was 800 A. The base material 3 (that is, the heat-resistant alloy member 100) on which the coat 4 and the heat shielding coating film 10 were formed was manufactured.

(Thermal cycle test)
The durability of the heat-resistant alloy member 100 manufactured in Example 1 and Comparative Example 1 was evaluated according to the following thermal cycle test method. That is, the number of cycles until the top coat 4 was peeled was measured with one cycle consisting of heating at 1093 ° C. for 10 hours and then naturally cooling. In addition, peeling of the topcoat 4 was confirmed visually. The result is shown in FIG.

As shown in FIG. 2, the heat-resistant alloy member 100 manufactured in Comparative Example 1 also has a certain degree of durability, but the heat-resistant alloy member 100 manufactured in Example 1 is the heat-resistant alloy member manufactured in Comparative Example 1. It had durability superior to 100. That is, it was found that the heat shielding coating film 10 according to the present embodiment is superior in durability than the conventional one.

FIG. 3 is a scanning electron micrograph of a partial cross section of the thermal barrier coating film produced in Example 1 after a thermal cycle test. Note that FIG. 3 and FIG. 4 to be described later are shown with the contrast of the photograph changed so that the boundary is clear.
As shown in FIG. 3, in the member manufactured in Example 1, metal particles 11 were deposited in the bond coat 1 having an oxide skeleton structure in the thermal cycle test, and the metal oxide 11 a was further interposed between the metal particles 11. Is formed. Further, by using image analysis software for the photograph shown in FIG. 3, the thickness W of the metal oxide 11a included in the bond coat 1 having an oxide skeleton structure, and the shortest distance D between the metal oxides 11a. In addition, the total area of the bond coat 1 having an oxide skeleton structure and the total area of the metal oxide 11a were measured. As a result, the thickness W of the metal oxide 11a is 0.3 μm to 7 μm, the shortest distance D is 6 μm, and the total area of the metal oxide 11a is the total area of the bond coat 1 having an oxide skeleton structure. With respect to 2.5%.

Further, when the element distribution of the metal oxide 11a was measured and evaluated with a wavelength dispersive X-ray spectrometer, it was found that 99% by weight of the total metal oxide 11a was aluminum oxide. It was also found that Ni, Cr, and Co were included as components of the metal oxide 11a other than aluminum oxide.

FIG. 4 is a drawing-substituting photograph obtained by photographing a partial cross section of the heat shielding coating film produced in Comparative Example 1 after a thermal cycle test with a scanning electron microscope.
As shown in FIG. 4, in the heat resistant alloy member 100 manufactured in Comparative Example 1, unlike the case of Example 1 shown in FIG. 3, the metal oxide 11a is not formed (indicated by reference numeral 1 ′ in FIG. 4). Part), it is homogeneous.

(Summary)
Usually, when the metal particles 11 are deposited by LPPS, the layer on which the metal particles 11 are deposited (that is, the bond coat 1 ′) has a large elongation at a high temperature. That is, such characteristics indicate that deformation resistance is small and plastic deformation is easy. Therefore, the plastic deformation accumulates in the bond coat 1 ′ as the number of thermal cycles that repeat high and normal temperatures increases, and the top coat 4 that is in close contact with the bond coat 1 ′ tends to peel off. .
However, according to the study of the present inventor, in the present embodiment, the metal oxide 11a is formed between the metal particles 11 after the metal particles 11 are deposited by HVOF. The bond coat 1 having an oxide skeleton structure containing 11a can be strengthened. Therefore, the heat-shielding coating film 10 according to the present embodiment has less accumulation in the bond coat 1 having a plastically deformed oxide skeleton structure, or has sufficient strength even if it accumulates temporarily. Therefore, it is considered that the durability is superior to the conventional one.

DESCRIPTION OF SYMBOLS 1 Bond coat which has skeleton structure of oxide 1 'Bond coat 10 Heat shielding coating film 11 Metal particle 100 Heat-resistant alloy member 2 Thermal growth oxide layer 3 Base material 4 Top coat

Claims

A heat shielding coating film formed on a substrate,
A plurality of metal particles comprising a metal, and a bond coat having an oxide skeleton structure formed by continuously bonding the metal oxide between the metal particles. Shielding coating film.
In the cross section of the bond coat,
2. The heat shielding coating film according to claim 1, wherein the thickness of the metal oxide is 0.5 μm or more and 20 μm or less.
In the cross section of the bond coat,
There are at least two oxides of the metal on the periphery of the metal particles;
The heat shielding coating film according to claim 1 or 2, wherein the shortest distance between the two metal oxides in the metal particles is 5 µm or more and 100 µm or less.
In the cross section of the bond coat,
The total cross-sectional area of the oxide of the metal is 40% or less with respect to the total cross-sectional area of the bond coat having the skeleton structure of the oxide. The heat shielding coating film as described in 1.
The heat shielding coating film according to claim 1 or 2, wherein the metal particles are bonded to other adjacent metal particles by at least one metal bond.
The metal contains aluminum, and further contains at least one selected from the group consisting of nickel, chromium and cobalt,
The amount of aluminum oxide contained in the metal oxide is 90% by weight or more with respect to the total amount of the metal oxide, according to claim 1 or 2, Heat shielding coating film.
A method for producing the heat-shielding coating film according to claim 1 or 2,
A method for producing a heat shielding coating film, comprising the step of depositing the plurality of metal particles by a high-speed flame spraying method.
A heat-resistant alloy member comprising at least a base material containing a metal and the heat shielding coating film according to claim 1 or 2.