JPH09202962A - Zirconia coated member, its production, device therefor and turbine member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a zirconia coated member having high mechanical properties and in which cracking and peeling are hard to occur by forming a zirconia coating layer composed of columnar crystals essentially consisting of ZrO2 on the surface of a bonding layer formed on a metallic base material by coating. SOLUTION: A bonding layer 2 preferably composed of M-Cr-Al-Y (M denotes Ni, Co and Fe) is formed on a metallic base material 1, e.g. contg. Ni, Cr, Co or the like and having high strength by a pressure reduction plasma thermal spraying or physical vapor deposition method. A zirconia coating layer 3 essentially consisting of ZrO2 and contg. Cab, MgO, Y2 O3 , CeO2 or the like is formed on the bonding layer 2. This zirconia coating layer 3 is composed of crystals contg. tetragonal crystals composed of columnar crystals by >=90%, preferably, this crystals grow to form into one crystalline body, and the oriented crystals in the orientation of the Miller Indexes (200) and/or (002) are contained by >=80% by area ratio. Moreover, the coating layer 3 is formed preferably by a physical vapor deposition method while the metallic base material 1 is heated to >=700 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zirconia coated member suitable for use in a high temperature or high temperature corrosive environment, a method for producing the same, and an apparatus for producing the same.

[0002]

2. Description of the Related Art Generally, in a gas turbine plant for power generation and the like, in order to improve power generation efficiency, the temperature of the gas turbine is increased. Along with this increase in temperature, it is desired to improve the heat resistant temperature and high temperature oxidation resistance of gas turbine members. Ni-based or Co-based high temperature heat resistant alloys have been developed as materials for these members, and the heat resistant temperatures have also been improved. . However, the heat resistant temperature is limited to about 850 ° C.

For this reason, ceramic materials have been investigated for the purpose of further improving durability at high temperatures, but they have not been applied in earnest since they have problems in toughness and the like compared with metal materials when used as structural materials. . Therefore, in order to cope with such a high temperature of the member, a means for preventing the member from becoming a high temperature has been actively studied.

That is, one of such methods is a method of cooling a member, and the other method is a method of coating the surface of the member with a ceramic having a small thermal conductivity.

Such a coating is called a thermal barrier coating and has a substantial temperature of a metal substrate of 50 ° C. as compared with a coating without the thermal barrier coating.
It can be suppressed up to 100 ° C. Zirconia is a ceramic that constitutes the thermal barrier coating. This zirconia has not only excellent mechanical properties but also low thermal conductivity.

By the way, zirconia has three crystal structures of a monoclinic system, a tetragonal system and a cubic system, and the tetragonal system is the most excellent from the viewpoint of mechanical properties. Pure zirconia (Zr
O ₂ ) is a stable phase of monoclinic crystals at room temperature, but when the temperature is increased, the monoclinic system changes to tetragonal at about 1000 ° C.
At about 2300 ° C., a tetragonal to cubic crystal reversibly undergoes a phase transition. The occurrence of this phase transition and the accompanying volume change are obstacles for the practical use of pure zirconia. That is, during the cooling process in the sintering process of zirconia, zirconia undergoes a phase transition from tetragonal to monoclinic, which is inferior in mechanical properties, and at that time, a large volume expansion occurs, so that zirconia self-destructs in combination with reduced mechanical properties. I am afraid. In order to eliminate the phase transition in this cooling process, it is usual to carry out tetragonal and cubic crystals having excellent mechanical properties to room temperature, that is, in order to stabilize the high temperature phase, Y ₂ O ₃ , CaO, MgO, etc. The compound is added and used. As a result, the tetragonal to monoclinic phase transition that occurs during the cooling process can be suppressed, and a tetragonal or cubic crystal having excellent mechanical properties from room temperature to high temperature can be obtained.

Further, since the thermal barrier coating is a coating made of a ceramic having different physical properties from the heat-resistant alloy constituting the metal base material, there is a problem in the adhesion strength between the metal base material and the zirconia coating layer and its reliability. . In particular, in a gas turbine, etc., the thermal cycle caused by repeated start and stop causes high-temperature oxidation and high-temperature corrosion on the surface of the metal base material, which lowers mechanical strength and chemical resistance at high temperatures, resulting in peeling of the zirconia coating layer. , And damage such as falling off occurs.

Therefore, as a method of solving such a problem, there is a method of providing a bonding layer composed of a metal alloy layer between the metal base material and the zirconia coating layer. This tie layer is
A so-called MCrAlY-based alloy containing Ni or Co as a main component and having Cr, Al, Y, etc. added thereto, which is excellent in high temperature oxidation resistance and high temperature corrosion resistance, is often used. The bonding layer and the zirconia coating layer used for the thermal barrier coating are mainly formed by the atmospheric plasma spraying method. In this case, the adhesion mechanism between the zirconia coating layer and the bonding layer is merely mechanical bonding, and its strength is said to be ² to 5 kg / mm ² . The reason why the zirconia coating layer used for the bonding layer or the thermal barrier coating is mainly formed by the atmospheric plasma spraying method is that the coating formation rate is high and the economy is excellent.

However, the bonding layer and the zirconia coating layer formed by the atmospheric plasma spraying method have many pores. Since these are used in a high temperature corrosive environment containing corrosive impurities in the fuel, there is a problem of high temperature oxidation and high temperature corrosion of the bonding layer or the zirconia coating layer having a porous structure with many pores. The bonding layer is a component having excellent oxidation resistance and corrosion resistance, but it does not necessarily exhibit the oxidation resistance and corrosion resistance expected of the original alloy material depending on the forming method thereof.

According to the results of the thermal cycle test of the thermal barrier coating composed of the bonding layer and the zirconia coating layer formed by atmospheric plasma spraying in a high temperature oxidizing or high temperature corrosive environment, its durability is remarkably high. Low, it is known that the zirconia coating layer peels off. this is,
It is considered that the bond between the bonding layer and the zirconia coating layer is mechanically weak in nature, and the surface of the bonding layer at the boundary is oxidized or corroded to further reduce the adhesion. . Further, peeling of the zirconia coating layer occurs not only on the boundary surface with the bonding layer but also in the zirconia coating layer.

[0011]

In view of such a point,
The object of the present invention is to secure mechanical strength, high temperature oxidation, even if the thermal cycle under a high temperature corrosive environment is repeated, cracks and peeling in the zirconia coating layer are unlikely to occur for a long period of time and the zirconia coating member. It is to provide a manufacturing method and a manufacturing apparatus.

[0012]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted extensive research on the crystal structure and film structure of the zirconia coating layer, and as a result, have shown that the excellent mechanical properties of the zirconia coating layer are obtained. It was found that it is important to control the crystal structure and the microstructure of columnar crystals in order to secure the length and prolong the peeling life in a high temperature atmosphere.

The present invention comprises a metal base material, a bonding layer coated on the metal base material, and a zirconia coating layer containing ZrO ₂ as a main component coated on the bonding layer. A zirconia-coated member having the following structure, wherein the crystals forming the zirconia coating layer are tetragonal crystals each having a columnar crystal structure.
% Or more of the zirconia-coated member.

The present invention preferably uses the Miller index (20
The crystal having an orientation in the (0) and / or (002) orientation has an area ratio of 8 on the surface of the zirconia coating layer.
0% or more, the metal base material contains at least one of Ni, Cr, Co, and the bonding layer is M-C.
A crystal body consisting of an r-Al-Y layer (where M represents at least one of Ni, Co, and Fe), wherein each crystal grain consisting of columnar crystals of the zirconia coating layer has one crystal grain. It grows up.

The present invention is also a turbine member comprising the zirconia coating member.

In the method for producing a zirconia-coated member of the present invention, the bonding layer is formed on the metal substrate, and the zirconia coating layer is further formed on the bonding layer by a physical vapor deposition method. The layer is formed by reduced pressure plasma spraying or physical vapor deposition.

Further, in the method for producing a zirconia-coated member according to the present invention, preferably, ZrO ₂ is a main component in the formation of the zirconia-coated layer, and CaO, MgO, Y ₂ O ₃ ,
A zirconia target material containing any one or more of CeO ₂ is irradiated with an electron beam to evaporate the target material and form the target material on the bonding layer.
And, during the film formation, the metal base material is continuously heated, preferably the metal base material temperature is 700 ° C. or higher, and
The temperature is kept below the solution heat treatment temperature of the metal base material, and only the metal base material is locally heated.

The apparatus for producing a zirconia-coated member according to the present invention has a metal-base-material heating device for locally heating only the metal base material at the time of forming the zirconia coating layer, arranged around the metal base material. Preferably, the metal base arranging device is arranged at a position where the radiant heat from the metal base heating device is focused, and the heat sensor for measuring the temperature of the metal base is the metal base. It is arranged in the vicinity of the material, and the signal from the heat sensor is fed back to the metal base material heating device.

Preferably, the apparatus for producing a zirconia-coated member according to the present invention is a batch type apparatus in which a plurality of the metal base material heating devices are independently arranged around the metal base material and a door is provided, for example, a door. Is a batch type furnace that opens and closes to attach the metal base material, and one or more metal base material heating devices are arranged on the door. Further, preferably, the metal heating device is provided with a heater element made of graphite, and the heater element is exposed at a portion of the metal heating device facing the metal base material. The part of is surrounded by a heat insulating plate. Further, more preferably, a plurality of the heat sensors are provided, and signals from the heat sensors are fed back to the plurality of different metal base material heating devices, respectively, and the plurality of metal base material heating devices are independently provided. This is a controlled device for manufacturing a zirconia coated member.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the zirconia coating member will be described.

FIG. 1 is a cross-sectional view showing a specific example of the zirconia-coated member of the present invention, in which a tetragonal crystal composed of columnar crystals is formed by X-ray diffraction on a bonding layer 2 formed by coating on a metal substrate 1. A zirconia coating layer 3 containing 90% or more of the measured value is formed.

The material of the metal base material can be appropriately selected from heat-resistant metal materials according to the purpose, but is preferably N.
A heat-resistant metal containing at least one of i, Cr, and Co, and more preferably a heat-resistant metal containing at least one of Ni, Cr, and Co as a main component is used.

The bonding layer is a material having heat resistance and is not particularly limited as long as it adheres to the metal material and the zirconia coating layer, but mainly Ni or Co having excellent properties of high temperature oxidation and high temperature corrosion resistance is mainly used. A so-called MCrAlY-based alloy containing Cr, Al, Y, etc. as a component is preferable. It is preferably a dense layer with few pores. In addition, in the present specification, a metal substrate on which a bonding layer is provided may be simply referred to as a metal substrate.

The material of the zirconia coating layer in the present invention is mainly composed of ZrO ₂ , Y ₂ O ₃ , CaO and MgO.
Zirconia whose high temperature phase is stabilized by adding, etc., and preferably contains 85 to 95% by weight of ZrO ₂ and 5 to 15% by weight of Y ₂ O ₃ .

In the preferred embodiment of the present invention, the orientation of the zirconia coating layer is particularly defined for the following reason.

The cracking / peeling of the zirconia coating layer occurs when the crack propagates parallel to the bonding layer. When the cracks propagate easily, the inventors of the present invention have a cleavage plane that is most likely to peel off in the film crystal structure, that is, a Miller index (111) plane is laminated in parallel to the bonding layer, and the ratio of the crystal is I found out that it was when there were many. That is, by making the (111) plane of the zirconia coating layer not parallel to the bonding layer,
It is possible to provide a zirconia coating layer which has excellent mechanical strength and is unlikely to cause cracking or peeling of the coating even in a thermal cycle operation for a long time.

Therefore, in the present invention, the crystal having an orientation in the orientation of the Miller index (111) among the above crystals is 70% or less, preferably 50% or less, more preferably 20% in terms of the area ratio on the zirconia-coated surface. Below.

In the present invention, preferably, the crystals of the zirconia coating layer are oriented in the (200) and (002) directions so that peeling easily occurs (11
1) A film whose surface is not parallel to the bonding layer and which has high mechanical strength can be provided.

In a preferred embodiment of the present invention, the orientation of the zirconia coating layer is either the (200) plane or the (002) plane, or the proportion of the orientation planes in which these are mixed is the area on the surface of the zirconia coating layer. When the ratio is preferably 80% or more, more preferably 95% or more, it is possible to provide a zirconia coating layer which is particularly excellent in mechanical strength and does not cause cracking or peeling of the coating even in a thermal cycle operation for a long time.

Crystal planes other than (200) and (002) {HKL} = (311), (113), (22)
Even if 0) and (202) are present, their superiority or inferiority does not change.

Further, in addition to controlling the crystal orientation, the microstructure of each columnar crystal is made into a structure in which fine crystal grains to be laminated are fused and integrated with each other, whereby mechanical strength and A film structure having an excellent peeling life can be obtained.

This is because, for example, the number of (111) planes that easily peel off decreases, and the crystal structure also becomes a desirable orientation plane.

The zirconia coating layer according to the present invention is preferably a dense layer with few pores.

The zirconia-coated member of the present invention is preferably used not only for turbine members, but also for various engines and boilers.

Next, the manufacturing method and apparatus of the present invention will be described with reference to specific examples. In producing the zirconia-coated member of the present invention, a bonding layer is formed on a metal substrate manufactured by a conventional method, preferably by low pressure plasma spraying or a physical vapor deposition method, and a physical vapor deposition method is further formed on the bonding layer. To form a zirconia coating layer.

In forming the zirconia coating layer, for example, when the zirconia target material is evaporated by irradiation with an electron beam and heated to cover the metal base material, a film is formed by the evaporated molecules, so that the structure of the film is columnar crystals. And can control the crystal orientation and the microstructure.

Specifically, for example, it is manufactured as follows.

The surface of a heat-resistant metal base material, for example, a metal base material composed mainly of at least one of Ni, Cr, and Co is roughened by degreasing and blasting using alumina particles. Next, this metal base material is mounted in a vacuum chamber, vacuumed until a predetermined vacuum degree is reached, and then A
The pressure is set to several tens Torr in an atmosphere of any one of r, He, H ₂ , and N ₂ or a combination thereof.

Next, plasma is generated and the number of metal base materials is set to 1
After heating to 00 ° C., one of Ni, Co, and Fe,
Alternatively, a sprayed powder containing Cr and Al in a combination thereof and further containing any one of Hf, Ta, Y, Si and Zr or a combination thereof is mixed with plasma to coat the surface of the metal base material.

However, the bonding layer thus formed by low pressure plasma spraying becomes a very dense film with almost no oxides or pores in the film, as compared with the bonding layer by atmospheric plasma spraying, and high temperature oxidation resistance. , High temperature corrosion resistance is greatly improved.

The bonding layer can also be formed by a physical vapor deposition method in which zirconia is coated. According to this, it is possible to form a very dense bonding layer having few oxides and pores in the bonding layer, and to make the bonding layer surface smooth and to make the surface of the zirconia coating layer very smooth. In addition, it becomes easier to control the crystal orientation.

The bonding layer thus formed is coated with zirconia by a ceramic (zirconia) coating device. As the zirconia coating apparatus, a general ceramic coating apparatus capable of forming a ceramic coating by physical vapor deposition can be used.

FIG. 2 shows a preferred example of the zirconia coating apparatus of the present invention. This zirconia coating device is composed of a vacuum chamber 4, a vacuum exhaust device (not shown), and a control device and a power supply device (not shown). The controller (not shown) includes vacuum exhaust, electron beam current, electron beam scanning,
Means for controlling heating of the metal substrate, driving of the metal substrate, etc. are provided.

A crucible 5 is arranged in the lower portion of the vacuum chamber 4, and a zirconia target material 6 is attached to the crucible 5.

On the other hand, in the upper part of the vacuum chamber 4, there is provided a metal base material driving device 7 which is rotationally driven by a motor (not shown), and the metal base material 1 is mounted on the metal base material driving device 7. . A metal base material heating device 8 for locally heating the metal base material 1 is provided in the peripheral portion of the metal base material 1 inserted into the metal base material driving device 7.

When the metal base material 1 coated with the bonding layer is coated with zirconia, first, the zirconia target material 6 is attached to the crucible 5 in the vacuum chamber 4, and the metal base material 1 is attached to the metal base material. It is attached to the material driving device 7 and the inside of the vacuum chamber 4 is set to 10 ^-2 to 10 ^-4 P by the vacuum exhaust device.
Evacuate until the degree of vacuum in a is reached.

Next, the zirconia target material 6 is irradiated with an electron beam by an electron beam generator (not shown) to melt the surface of the zirconia target material. At this time, the electron beam current is controlled so that a predetermined evaporation rate is maintained while the surface is always melted, and the electron beam is scanned.

While the metal base material 1 is coated with zirconia, the metal base material 1 is rotated by the metal base material driving device 7 and is heated to 700 ° C. or higher by the metal base material heating device 8. The metal base material heating device 8 has a structure for locally heating only the metal base material 1.

In the present invention, when controlling the crystallinity of the film, that is, controlling the orientation and the microstructure, the metal substrate is continuously heated from the start of film formation to the end of film formation, particularly at 700 ° C. or higher, preferably Is preferably maintained at 750 ° C. or higher, more preferably 800 ° C. or higher, and the heating temperature is preferably accurately controlled so that the entire metal base material is uniformly heated at a predetermined temperature.

When the heating temperature of the metal substrate is 700 ° C. or lower, the crystal orientation plane of the zirconia coating layer tends to be the (111) direction. This is because the crystal growth energy is small, and thus the evaporated zirconia atoms form the highest packing density plane, that is, the (111) plane, which is easy to stack.

On the other hand, the heating temperature of the metal substrate is 700
By setting the temperature to be at least ℃, the crystal orientation plane can be made a plane other than (111), and as the temperature increases (20
It is preferable because the ratio of 0) and (002) can be increased.

Further, the heating temperature is set to 700 ° C. or higher, and the heating is continued until the film formation is completed, whereby the fusion and integration of the fine crystal grains to be laminated also progresses. Further, as the temperature is raised, this fusion and integration is promoted, and each columnar crystal becomes one crystal body. It was also found that the columnar crystals, which became one crystal, had a coating structure that was extremely strong against thermal stress and were excellent in heat stress and peel resistance.

The upper limit of the heating temperature is preferably the solution heat treatment temperature of the metal substrate in order to prevent deterioration of the mechanical properties of the metal substrate.

Local heating of only the metal base material is preferable because it prevents the temperature of the entire vacuum chamber from rising and does not require a large equipment cost for the construction of the vacuum apparatus.

FIG. 3 is a schematic configuration diagram of a metal base material heating apparatus which is a part of the apparatus for producing a zirconia coated member according to the present invention. FIG. 3- (a) shows a view in which the metal base material 1 is arranged in the metal base material heating device 8 and a view seen from the direction A.
FIG. 3- (c) shows (b) and another example.

The metal base material heating device 8 is composed of a heater heating element (not shown) and a heat insulating plate disposed around the heater heating element.

In the example shown in FIG. 3- (b), the metal base material 1 is arranged in the semi-cylindrical metal base material heating device 8, and the metal base material heating device 8 and the zirconia target material 6 are , Are arranged on concentric circles centered on the metal substrate 1. By doing so, the radiant heat from the zirconia target material 6 and the metal base material heating device 8 is evenly applied to the metal base material 1, and the entire metal base material 1 is uniformly heated. FIG. 3- (c) is another example that has the same effect, and is composed of a U-shaped metal base material heating device 8 arranged at equal intervals from the metal base material 1.

FIG. 4 shows a more preferable example of the zirconia coating apparatus of the present invention. Inside the vacuum chamber 4, a plurality of independent metal base material heating devices 8 are provided.
The metal base material heating device 8 is composed of a heater element 9 made of graphite and a heat insulating plate 10 arranged around the heater element 9. The heater element 9 can improve the thermal efficiency by exposing the portion facing the metal base material 1 and covering the other portion with the heat insulating plate 10. Although the zirconia evaporated from the zirconia target material 6 on the crucible 5 adheres to the entire metal substrate heating device 8, the zirconia adhered to the heater element made of graphite can be easily scraped off, resulting in a decrease in thermal efficiency. Can be prevented.

One of the heating devices 8 is a vacuum chamber 4.
Is fixed to the upper part of the heating device by a heating device support 11, and another unit of the heating device 8 is fixed to the rear side surface of the vacuum chamber 4. On the other hand, yet another unit of the heating device 8 is fixed to the door 12 of the vacuum chamber 4.

When the door 12 is closed, the metal substrate 1 is surrounded by a plurality of heating devices 8 as shown in FIG. By doing so, the radiant heat from the zirconia target material 6 and the metal base material heating device 8 is evenly applied to the metal base material 1, and the entire metal base material 1 is uniformly heated.

When the metal base material 1 is attached and detached to a predetermined position of the vacuum chamber 4, the metal base material 1 can be easily attached and detached from the door 12 side by opening the heating device 8 and the door 12 integrally. By the way, in the portion of the metal substrate 1 located on the metal substrate driving device 7 side, a large amount of heat escapes through the metal substrate driving device 7. Therefore, the metal substrate 1 usually has a complicated three-dimensional shape. Therefore, the temperature distribution of the metal substrate 1 tends to be non-uniform.

In the present invention, in particular, it is necessary to make the temperature distribution of the entire metal substrate 1 uniform and to accurately control the temperature to a predetermined temperature. Therefore, preferably, the metal base material heating device 8 is composed of a plurality of heating devices, and is configured to be able to independently control the temperature. Further, a plurality of thermocouples, which are heat sensors for controlling the temperature, are inserted into the drive shaft of the metal base material drive device 7 and arranged at the portion closest to the metal base material 1.

By using the signal from this thermocouple as the control signal for the substrate heating device 8, it is possible to perform accurate temperature control at a predetermined temperature.

As described above, by disposing a plurality of heating devices around the metal base material 1 and further disposing the thermal sensor in the vicinity of the metal base material 1, uniform heating can be performed at the time of film formation, and the zirconia coating can be performed. The crystal structure and microstructure of the layer can be controlled more precisely.

Further, since this heating method is a local heating in the vicinity of the metal base material, the temperature of the entire vacuum chamber is prevented from rising, and a large equipment cost is not required for the construction of the vacuum apparatus.

As described above, according to the preferred embodiment of the production method of the present invention, the metal base material is uniformly heated at a temperature of 700 ° C. or higher until the film formation is completed, and the crystal structure of the zirconia coating layer becomes (200) ( 002) Since it has a main orientation, and each columnar crystal becomes one crystal, it has excellent mechanical strength,
It is possible to form a zirconia coating layer which is excellent in heat cycle characteristics and long-term use at high temperature.

[0067]

The present invention will be described below with reference to examples. In the embodiment according to the present invention, the heating temperature of the metal substrate is 400 ° C. to 900 ° C. when forming the zirconia coating layer.
Multiple changes were made within the range. Also, the metal base material temperature is 700 ° C.
In the case of, the temperature distribution on the metal substrate 1 was made uniform and the temperature distribution on the metal substrate 1 was made non-uniform.

First, a Co-based FSX414 base material (manufactured by Ishikawajima Precision Casting Co., Ltd.) was degreased and washed, and then blasted using an alumina grid to obtain Co, Ni, Cr, Al,
A alloy powder of Y was added in an Ar atmosphere of 20 Torr
Thermal spraying was performed using r-He plasma to obtain a coating excellent in high temperature oxidation and high temperature corrosion. The thickness of the film was uniform and was about 150 μm.

Next, 8% Y is added to the CoNiCrAlY layer.
To form the ₂ O ₃ -ZrO ₂ zirconia coating layer. At the time of this formation, the device shown in FIG. 2 was used. First, in the vacuum chamber 4, the F
The metal base material 1 made of the SX414 base material was mounted, and the crucible 5 was mounted with the zirconia target material 6.

After that, the inside of the vacuum chamber 4 was evacuated to the level of 10 ^-4 Pa, and then the metal base material 1 was rotated while being heated at each temperature, and the zirconia target material 6 was evaporated by the electron beam, so that the metal base material 1 was evaporated. Was formed into a film. At this time, scanning of the electron beam was controlled in order to keep the film formation rate almost constant. The film thickness obtained was about 150 μm.

The conventional product was manufactured by using atmospheric pressure plasma spraying for both the bonding layer and the zirconia coating, using a metal base material made of the same material as that of the above-mentioned embodiment, the bonding layer and the zirconia coating layer, and having the same thickness as that of the above-mentioned embodiment. And A cross-sectional view of this conventional zirconia-coated member is shown in FIG. In this conventional product, as in FIG. 1, the metal base material 1 is covered with the bonding layer 13, and the zirconia layer 14 is formed thereon. However, many pores are present in the bonding layer and the zirconia coating layer in the conventional product.

With respect to these conventional products and examples, X-ray diffraction (crystal structure) and thermal cycle tests were conducted while controlling the temperature distribution of the metal substrate. The heat cycle test is performed by heating and holding at 1000 ° C. for 30 minutes in the air atmosphere, and then 20 to 2
It was carried out by determining the number of heat cycles until the zirconia coating layer was peeled off, while keeping it in water at 5 ° C as one cycle. The results are shown in Table 1. Table 1 (Comparison between conventional product and example) Base material temperature (° C) Crystal structure Number of heat cycles until film peeling Conventional product 1-Texagonal and monoclinic mixed 92 Conventional product 2-Same 79 Conventional product 3-Id 105 Example 1 400 * 90% or more tetragonal 260 Example 2 600 * Id 330 Example 3 700 Id 1050 Example 4 700 * Id 5750 Example 5 800 * Id 8500 Example 6 900 * Same as above 8650 (Note) * indicates temperature control so that the temperature distribution of the metal substrate is uniform. FIG. 6 shows the difference in temperature distribution between Example 4 in which the temperature control is made precise and the temperature distribution of the metal base material is made uniform, and Example 3 in which it is not so. As shown in Table 1, the conventional zirconia coating layer had a crystal structure composed of tetragonal crystals and monoclinic crystals.
On the other hand, the zirconia coating layer according to the present invention had a crystal structure of 90% or more tetragonal. Further, in the conventional zirconia coating member, peeling of the zirconia coating layer occurred after 79 to 105 thermal cycles. On the other hand, in the examples according to the present invention, the number of heat cycles is about three times or more, but in particular, the temperature of the base material is set to 700 ° C. or higher and the temperature is precisely controlled to make the temperature distribution of the metal base material uniform. By doing so, the peeling life is remarkably improved.

In the heat cycle test result of Example 3 in which the temperature distribution has a large variation, the zirconia coating layer starts to peel off quickly, and the number of heat cycles until the film peeling is short as compared with Example 4 in which the temperature distribution has a small variation. It was

As described above, it can be confirmed that the zirconia-coated member according to the present invention is superior in mechanical strength and heat cycle characteristics to the conventional zirconia-coated member.

Next, in these conventional products and examples, the crystal orientation was measured by X-ray diffraction by changing the substrate temperature between 600 and 900 ° C. by 50 ° C., and the structure of the surface of the zirconia coating layer was observed by an electron microscope. went.

In the structure observation, the proportion of (111) and (200) (002) on the surface of the zirconia coating layer was determined. Table 2 shows the results.

Table 2 (Comparison between Conventional Product and Example) Test Piece Base Material Temperature (° C.) Surface Occupancy (%) ^{(111) (200) / (002)} Conventional Product 4-Various Crystal Faces Mixed Conventional Product 5-Same as Conventional Product 6-Same Example 7 200 100 0 Example 8 400 100 0 Example 9 600 90 10 Example 10 650 80 20 Example 11 700 20 80 Example 12 750 10 90 Example 13 800 0 100 Example 14 850 0 100 Example 15 900 0 100

By forming the zirconia coating layer at a metal substrate temperature of 700 ° C. or higher, the area ratio occupied by (200) and (002) was 80% or more, and a marked improvement in the peeling life was obtained. In addition, the columnar crystal at this time was one large grown crystal grain.

[0079]

As described above, according to the present invention,
A coating layer with a crystalline structure with excellent mechanical strength is obtained, and even for long-term use in a high temperature atmosphere and thermal cycle operation,
It is possible to provide an extremely excellent zirconia-coated member that can prevent cracking or peeling of the zirconia coating layer.

By forming the zirconia coating layer preferably while uniformly heating the metal substrate at a temperature of 700 ° C. or higher, the crystal orientation and the microstructure of columnar crystals can be controlled. More preferably by forming the bonding layer by low pressure plasma spraying or physical vapor deposition method,
It is possible to provide a zirconia-coated member that is more excellent in high-temperature oxidation characteristics, is more stable over a long period of time, and is less susceptible to cracking or peeling.

[Brief description of drawings]

FIG. 1 is a sectional view of a zirconia-coated member according to the present invention.

FIG. 2 is a schematic configuration diagram of an apparatus for manufacturing a zirconia-coated member according to the present invention.

FIG. 3 is a schematic configuration diagram of a metal base material heating device which is a part of a zirconia coated member manufacturing apparatus according to the present invention.

FIG. 4 is a schematic configuration diagram of a preferred embodiment of a zirconia-coated member manufacturing apparatus according to the present invention.

FIG. 5 is a sectional view of a conventional zirconia-coated member.

FIG. 6 is a graph showing a temperature distribution during zirconia coating in Examples 3 and 4.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Metal substrate 2 Bonding layer 3 Zirconia coating layer 4 Vacuum chamber 5 Crucible 6 Zirconia target material 7 Metal substrate driving device 8 Metal substrate heating device 9 Heater element 10 Heat insulating plate 11 Heating device support 12 Door 13 Conventional bonding layer 14 Conventional zirconia coating layer

Claims (17)

[Claims] 1. A metal base material, a bonding layer coated on the metal base material, and ZrO ₂ coated on the bonding layer.
A zirconia coating member comprising a zirconia coating layer containing as a main component, wherein the crystal forming the zirconia coating layer contains 90% or more of tetragonal crystals composed of columnar crystals. Element. 2. The Miller index (200) and / or (0
The zirconia-coated member according to claim 1, wherein the crystal having orientation in the (02) direction is 80% or more in terms of the area ratio on the surface of the zirconia coating layer. 3. The metal base material contains at least one of Ni, Cr and Co, and the bonding layer is M-Cr-.
The zirconia-coated member according to claim 1 or 2, comprising an Al-Y layer (where M represents at least one of Ni, Co, and Fe). 4. The crystal grains of columnar crystals of the zirconia coating layer grow as one crystal body.
The zirconia coating member according to any one of 3 to 3. 5. A turbine member comprising the zirconia coating member according to any one of claims 1 to 4. 6. The zirconia-coated member according to claim 1, wherein the bonding layer is formed on the metal substrate, and the zirconia coating layer is formed on the bonding layer by a physical vapor deposition method. Manufacturing method. 7. The method for producing a zirconia-coated member according to claim 6, wherein the bonding layer is formed by low pressure plasma spraying or physical vapor deposition. 8. Zr during the formation of the zirconia coating layer
The O ₂ mainly _{CaO, MgO, Y 2 O 3} , CeO 2
A zirconia target material containing any one or more of the above, to evaporate the target material by irradiating the target material with an electron beam, to form the target material on the bonding layer, and during the formation of the metal. The method for producing a zirconia-coated member according to claim 6, wherein the base material is continuously heated. 9. The temperature of the metal base material at the time of forming the zirconia coating layer is 700 ° C. or higher and is maintained at the solution treatment temperature of the metal base material or lower.
The method for manufacturing the zirconia-coated member according to any one of 1. 10. The method for producing a zirconia coated member according to claim 6, wherein only the metal base material is locally heated when the zirconia coated layer is formed. 11. An apparatus for carrying out the method for producing the zirconia coating member according to claim 6, wherein the metal base material is heated only for locally heating the metal base material when the zirconia coating layer is formed. An apparatus for manufacturing a zirconia-coated member, characterized in that the apparatus is arranged around the metal base material. 12. The apparatus for producing a zirconia-coated member according to claim 11, wherein a plurality of the metal base material heating devices are independently arranged around the metal base material. 13. The apparatus for manufacturing a zirconia-coated member, wherein the metal base material arranging device is arranged at a position where the radiant heat from the metal base material heating device is focused. An apparatus for manufacturing a zirconia coated member according to. 14. An apparatus for producing the zirconia-coated member,
12. A batch type device provided with a door, wherein one or more of the metal base material heating devices are arranged on the door.
An apparatus for manufacturing a zirconia-coated member according to any one of claims 1 to 13. 15. The metal heating device is provided with a heater element made of graphite, and the heater element is exposed at a portion of the metal heating device facing the metal base material. The zirconia-coated member manufacturing apparatus according to claim 11, wherein the other portion is surrounded by a heat insulating plate. 16. A heat sensor for measuring the temperature of the metal base material is arranged in the vicinity of the metal base material, and a signal from the heat sensor is fed back to the metal base material heating device. Item 11. An apparatus for producing a zirconia-coated member according to Item 11 or 12. 17. A plurality of the heat sensors are provided, and signals from the heat sensors are fed back to the plurality of different metal base material heating devices, so that the plurality of metal base material heating devices are independently provided. The zirconia-coated member manufacturing apparatus according to claim 16, which is controlled.