JPH07305162A - Production of ceramic coating - Google Patents

Abstract

PURPOSE:To prepare a ceramic coating free from corrosion by steam and having stable adhesive strength by forming a bonding layer of an alloy of specified metals on the surface of a heat resistant alloy substrate and coating the bonding layer with an evaporated and ionized ceramic material. CONSTITUTION:A bonding layer of an alloy based on Ni or Co excellent in high temp. oxidation and corrosion resistances and contg. Cr, Al and one or more among Hf, Ta, Y, Si and Zr is formed by plasma spraying or other method on the surface of a substrate based on at least one among Ni, Co and Fe. Ceramics based on ZrO2 and contg. one or more among CaO, MgO and Y2O3 is evaporated and ionized and a ceramic coating is formed on the bonding layer. Film forming energy is synergistically increased and the objective ceramic coating excellent in adhesive strength is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a ceramic coating for producing a heat resistant member used in a high temperature or high temperature corrosive environment.

[0002]

2. Description of the Related Art Generally, in a gas turbine plant for power generation and the like, there is a tendency to increase the temperature of a gas turbine in order to improve power generation efficiency. Therefore, along with this increase in temperature, it is desired to improve the heat resistant temperature and high temperature oxidation resistance of the gas turbine member.
Heat resistant alloys for base or Co base high temperature have been developed and the heat resistant temperature has been improved, but the temperature is limited to about 850 ° C.

Therefore, ceramic materials have been studied for the purpose of further improving high temperature durability, but they have not been applied in earnest since they have a problem in toughness and the like when used as a structural material as compared with metal materials. Therefore, in order to cope with such a high temperature of the member, a method of 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 coatings are thermal barrier coatings (Thermal
It is also known that the actual temperature of the substrate can be suppressed by 50 ° C to 100 ° C as compared with the case where the heat shield coating is not applied. Further, as a ceramic constituting the heat shield coating, there is a zirconia (ZrO ₂ ) based material which has been conventionally used. This zirconia has the advantages of low thermal conductivity in addition to excellent mechanical properties.

Incidentally, zirconia has three crystal structures of monoclinic crystal, tetragonal crystal and cubic crystal, and the tetragonal crystal is the best 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, which causes self-destruction in combination with reduced mechanical properties. I am afraid. In order to eliminate the phase transition in this cooling process, usually, tetragonal or cubic crystal having excellent mechanical properties is carried over 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.

However, the tetragonal zirconia stabilized with Y ₂ O ₃ also has a drawback that when exposed to an atmosphere of 80 to 300 ° C. containing water vapor, a phase transition different from the phase transition due to thermal history occurs. Remain. For example, when a stabilized zirconia is used for a heat shield coating for a moving blade or a stationary blade used in an atmosphere containing water vapor like a gas turbine, there is no problem at an operating temperature of 1100 to 1400 ° C. In the temperature range of 80 to 300 ° C., which is passed or held at the time of starting and stopping the gas turbine, the stabilized zirconia has a drawback that it undergoes a phase transition from tetragonal to monoclinic (steam corrosion). Due to this steam corrosion, the zirconia coating layer is cracked and deteriorated, resulting in a marked decrease in durability.

Further, since the heat-shielding coating covers ceramics having different physical properties from the heat-resistant alloy constituting the base material, there is a problem in adhesion strength between the base material and the zirconia coating and its reliability. Particularly in a gas turbine, etc., thermal cycle such as start-up and stop causes high temperature oxidation and high temperature corrosion on the surface of the base material, resulting in deterioration of mechanical strength and chemical resistance at high temperature, resulting in damage such as peeling and dropping of the zirconia film. Occurs.

Therefore, as a method of solving such a point, there is a method of providing a bonding layer made of a metal alloy layer between the base material and the ceramic coating layer. This metal alloy layer is a so-called MC containing Ni or Co as a main component and having Cr, Al, Y, etc. added thereto, which has excellent properties of high temperature oxidation resistance and high temperature corrosion.
rAlY-based alloys are often used. The metal coating layer and the ceramic 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 ceramic coating layer and the metal alloy layer is merely mechanical connection, and the strength is 2 to 5 kg / mm ^2.
It is said that.

On the other hand, the reason why the ceramic coating layer used for the metal bonding layer and the heat shield coating is mainly formed by the plasma spraying method is that the coating forming rate is high and the economy is excellent. However, since the metal alloy layer and the ceramic coating layer are used in a high temperature corrosive environment due to impurities in the fuel at a high temperature, the metal alloy layer or the ceramic coating layer having a porous structure with many pores has a high temperature. Oxidation,
There is a problem of high temperature corrosion. The metal alloy layer is a component excellent in high temperature oxidation resistance and corrosion resistance, but it does not always exhibit the high temperature oxidation resistance and corrosion resistance expected of the original alloy material depending on the method of forming these coating layers.

However, as a result of a heat cycle test of a heat shield coating composed of a metal alloy layer or a ceramic coating layer formed by atmospheric plasma spraying in a high temperature oxidizing or high temperature corrosive environment, its durability is remarkably low, It is known that the ceramic coating layer peels off. This is because the bond between the metal alloy layer and the ceramic coating layer is mechanically weak in nature, and in addition, the surface of the metal alloy layer at the boundary portion is oxidized or corroded, and its adhesion force is increased. Is considered to be further reduced. Further, the peeling of the ceramic coating layer occurs not only in the boundary surface with the metal alloy layer but also in the ceramic layer.

As described above, in the conventional heat-shielding coating, cracks are generated in the ceramic coating layer due to steam corrosion, and durability is remarkably reduced. Further, it is considered that the surface of the metal alloy layer is changed due to high temperature oxidation, high temperature corrosion, etc., and the bonding force with the ceramic coating layer is further lowered, and the reliability of the heat shield coating is significantly lowered.

In view of the above points, the present invention has mechanical strength, is free from steam corrosion, and has a stable adhesive force between the metal alloy layer and the ceramic coating layer or in the ceramic coating layer for a long period of time. Therefore, it is an object of the present invention to obtain a method for manufacturing a ceramic coating that is resistant to cracking and peeling.

[0013]

The first invention is Ni, C
o, Fe on the surface of the base material composed of at least one of the main components, at least one of Ni, Co Cr, Al
A step of forming a bonding layer containing any one of Hf, Ta, Y, Si, and Zr or a combination thereof, and CaO, MgO, Y containing ZrO ₂ as a main component.
_And vaporizing and ionizing a ceramic made of any one of ₂ O ₃ or a combination thereof to coat it on the bonding layer of the above alloy.

In a second aspect of the invention, the step of forming the alloy bonding layer is performed by plasma spraying in any one atmosphere of Ar, He, H ₂ and N ₂ or a combination thereof in an atmosphere of 1 atm or less. And a step of coating the ceramic, the step of evaporating the ceramic, the step of ionizing the ceramic particles vaporized by the thermoelectron generator and the thermoelectron accelerator, the step of introducing a reaction gas, and heating the substrate. And a step of applying a voltage to the base material.

In a third aspect of the present invention, the ceramic coating is formed by physical vapor deposition, the coating contains 90% or more of tetragonal crystals, and the average concentration of the stabilizer Y ₂ O ₃ in the coating is 5 to 15 wt.
%, And the concentration in the minute region is 3 to 18
It is characterized in that it is distributed between wt%.

[0016]

According to the above manufacturing method, the film forming energy is increased synergistically by the collision of the ionized ceramic material with the base material, the excited reaction gas, the application of a negative voltage to the base material, and the heating of the base material. In addition, the adhesive strength is excellent, and even when used for a long period of time in a high temperature atmosphere, the ceramic coating layer can be prevented from cracking or peeling, and the metal alloy layer can be prevented from being oxidized.

[0017]

Example A surface of a heat-resistant alloy member composed mainly of at least one of Ni, Co, and Fe is roughened by degreasing and blasting using alumina particles. Next, this heat-resistant alloy member is inserted into a vacuum chamber and evacuated to a predetermined vacuum degree, and then Ar, He, H ₂ , N
₁ in any one of ₂ or in an atmosphere that combines them
Apply pressure of 0 Torr.

Next, after plasma is generated to heat the heat-resistant alloy member to several hundreds of degrees Celsius, at least one of Ni and Co contains Cr and Al, and Hf, Ta, Yi, and S.
A thermal spraying powder made of any one of i and Zr or a combination thereof is mixed into plasma to coat the surface of the heat resistant alloy member.

Thus, the film thus formed becomes a very dense film having almost no oxides or pores in the film as compared with the conventional film formed by atmospheric plasma spraying, and has high temperature oxidation and high temperature corrosion resistance. Greatly improved.

The MGrAlY layer thus formed is coated with a ceramic layer by the following ceramic coating device. That is, as shown in FIG. 1, the ceramic coating layer includes a vacuum chamber 1 for performing ceramic coating, a vacuum exhaust layer 2 including a diffusion pump DP and an oil rotary pump RP, and a control device and a power supply device (not shown). .

In the vacuum chamber 1, a crucible 3 for mounting a ceramic material is disposed below the vacuum chamber 1, and below the crucible 3 is provided an electron beam generator 4 for melting and evaporating the ceramic material. Further, an electron beam scanning device 5 is provided on one side of the crucible 3. Further, a thermoelectron generator 6 and a thermoelectron accelerator 7 for ionizing the ceramic material evaporated in the crucible 3 are provided on one upper side of the crucible 3, and the thermoelectron generator 6 detects an ionization current. The device 8 is connected, and the ionization current detection device 8 is connected to the thermionic accelerator 7. Further, a film forming rate detecting device 9 is provided above the crucible 3.

On the other hand, in the upper part of the vacuum chamber 1, there is provided a base material driving device 11 which is rotationally driven by a motor 10. The heat resistant alloy member 12 is detachably mounted on the base material driving device 11. There is. Then, in the vicinity of the heat resistant alloy member 12 mounted on the base material driving device 11, a base material resistance heating device 13 for heating the heat resistant alloy member 13 is provided.
Further, a voltage applying device 14 for applying a negative voltage to the heat resistant alloy member is connected to the base material driving device 11. Further, a reaction gas supply device 15 for oxygen or the like is connected to the vacuum chamber 1, and a gas flow rate control device 16 for controlling the introduction of the reaction gas and the gas flow rate in the middle thereof.
Is provided.

The control device (not shown) includes vacuum exhaust, electron beam current, electron beam scanning, thermionic generation amount,
Means for controlling gas flow rate, substrate heating, substrate voltage application, substrate driving, etc. are provided.

When the heat-resistant alloy member coated with the MCrAlY layer is coated with the ceramic layer, first, the ceramic material is attached to the crucible 3 in the vacuum chamber 1 and the heat-resistant alloy member 12 is attached to the base material driving device. 11 and the inside of the vacuum chamber 1 is set to 10 ⁻² to 10 by the vacuum exhaust device 2.
^-Evacuate until the degree of vacuum reaches ^-4 Pa. Next, the ceramic material is irradiated with an electron beam by the electron beam generator 4 to melt the surface of the ceramic material. At this time, the electron beam current is controlled so that a predetermined evaporation temperature is maintained with the surface always unraveled, and further the electron beam is scanned.

As shown in FIG. 2, a signal from any one or both of the film formation rate detector 9 and the ionization current detector 8 is sent to the electron beam generator 4 and the electron beam scanner 5. As shown in FIG. 3, the evaporation of the ceramic material is controlled by inputting a signal from any one or both of the film formation detection device 9 and the ionization current detection device 8 to the crucible resistance heating device 17. Then, the output of the heater 18 can be controlled to control the output.

The evaporated ceramic material is ionized by colliding with the thermoelectrons generated from the thermoelectron generator 6 and the thermoelectrons generated from the ceramic material itself. That is, the thermoelectrons are accelerated by the thermoelectron accelerator 7 to which a positive voltage is applied to promote ionization, and are attracted to the thermoelectron accelerator with a large kinetic energy. The thermoelectrons collide with the ceramic material evaporated during the flight. The generation of the thermoelectrons can be realized by passing a current through a tungsten filament of a refractory metal, etc., and the acceleration of the thermoelectrons can be realized by applying a voltage to the metal plate. All of these can be controlled by making the current and voltage variable.

In order to increase the probability of collision between the evaporated ceramic material and thermions, the thermionic generator 6 should be close to the evaporator so as not to affect the electron beam, and the thermionic accelerator should be used. 7 is provided at a position where the flight distance of thermoelectrons is long and the kinetic energy due to voltage application is large.

On the other hand, simultaneously with the evaporation and ionization of the ceramic material, a reaction gas such as oxygen is introduced into the vacuum chamber 1 by the gas flow rate control device 16 so that the ceramic coating has a stoichiometric composition. Are excited and activated by the thermoelectrons, and the reaction proceeds on the surface of the material.

On the other hand, the heat-resistant alloy member 12 is the base material driving device 1
The substrate resistance heating device 13 is rotated by 1
Is heated to about several hundred degrees Celsius by the voltage application device 1
4, a negative voltage of about several 10V to several 100V is applied.

Therefore, the ionized ceramic material is accelerated by the negative voltage and collides with the surface of the rotating heat-resistant alloy member 12 to form a ceramic film.

By the way, in addition to resistance heating, the heating of the substrate is
Any means such as lamp heating, high frequency heating, and electron beam heating may be used as long as it achieves this purpose, or a combination of these may be used. FIG. 4 is a diagram showing an embodiment of these heating means, (a) is heating means by the lamp 20, (b) is heating means by high frequency from the high frequency generator 21, and (c) is electron beam generator 22. This is an example in which a heating means using an electron beam from is adopted.

As described above, according to the method for producing a ceramic coating of the present invention, the ionized ceramic material collides with the base material, the excited reaction gas, and the negative voltage is applied to the base material.
Further, the film forming energy is synergistically increased by heating the base material and the like, and a ceramic film having excellent adhesion strength and a stoichiometric composition is formed.

By the way, as a result of repeated studies on the concentration and distribution of the stabilizer in the ceramic coating, in order to secure the excellent mechanical properties of the ceramic coating and prevent steam corrosion, it is difficult for the element to move. We have found that it is important to regulate and control the bias of elements that cannot be avoided in materials.

Therefore, the present invention firstly defines the average concentration of the stabilizer in order to make the ceramic coating have a tetragonal crystal structure excellent in mechanical strength, and to prevent steam corrosion of the ceramic coating, By defining the concentration distribution of the stabilizer, we achieved both mechanical properties that could not be achieved previously and complete prevention of steam corrosion.

Since steam corrosion is extremely sensitive to the amount of Y ₂ O ₃ , it is significantly affected by the concentration distribution in the formed sintering target material and coating film. In the case of ceramics such as zirconia, it is inevitable that the concentration of the stabilizer Y ₂ O ₃ has a distribution, that is, a bias. Nevertheless, conventional ceramic target materials and ceramic coatings have been managed only by the average concentration. Therefore, it was not possible to completely prevent steam corrosion.

In the ceramic coating of the present invention, 90% tetragonal ZrO ₂ is used in order to secure the required mechanical strength.
% Or more, and in order to achieve this, the average concentration of Y ₂ O ₃ is set in the range of 5 to 15 wt%. Y ₂ O ₃
When the average concentration exceeds 15 wt%, the amount of cubic ZrO ₂ increases and it becomes impossible to obtain sufficient mechanical strength. Further, if the average concentration of Y ₂ O ₃ is less than 5 wt%, it becomes impossible to suppress the decrease in mechanical strength due to steam corrosion. The constituent phase other than tetragonal may be monoclinic, cubic, or a mixture thereof.

Since the above-mentioned average concentration defines a wide range of average values, the actual concentration of the stabilizer in a ceramic film in which the average concentration is merely defined is
It permits the existence of a portion having a concentration significantly lower than the lower limit value of 5 wt% of the temperature range to a portion having a concentration significantly higher than the upper limit value of 15 wt%. On the other hand, from the viewpoint of preventing steam corrosion, even if the crystal structure is mainly tetragonal, it is necessary to set the concentration distribution of the stabilizer within an appropriate range, but the ceramic film is only defined by the average concentration. Then, the concentration outside the optimum temperature range is included.

On the other hand, in order to obtain a ceramic film having high mechanical strength, cubic Z having a high Y ₂ O ₃ concentration is used.
Y ₂ O ₃ rather than rO ₂ (15 wt% or more in average concentration)
A lower concentration of tetragonal ZrO ₂ is desirable.

Therefore, in the ceramic coating of the present invention, the concentration distribution of Y ₂ O ₃ in the minute region is defined in the range of ₃ to 18 wt% together with the average concentration of Y ₂ O ₃ described above. Regarding the Y ₂ O ₃ concentration distribution, the lower limit value is intended to suppress a decrease in mechanical strength due to steam corrosion. Therefore, in order to secure the mechanical strength and prevent the water vapor corrosion, it is necessary to set the temperature distribution in the minute region of Y ₂ O _{3 in} the range of ₃ to 18 wt%.

That is, the reason why the lower limit value of the concentration distribution in the minute region of Y ₂ O ₃ is defined as 3 wt% is Y ₂
If the concentration of O ₃ is less than 3 wt%, for example, 2
3 wt% when kept in the atmosphere at 00 ° C
The phase transition occurs in the lower portion and monoclinic crystals increase. As a result, the amount of tetragonal crystals necessary for ensuring mechanical strength cannot be obtained, and what is important is that the number of unstable tetragonal crystals causing steam corrosion rapidly increases. Further, the reason why the upper limit value of the concentration distribution of Y ₂ O ₃ is set to 18 wt% is that if the deviation exceeds 18 wt%, it is advantageous from the viewpoint of preventing steam corrosion, but cubic crystals increase rapidly and mechanical The amount of tetragonal crystals required to secure the strength cannot be obtained.

In the ceramic coating of the present invention, Y ₂
The concentration distribution of O _{3 in} the minute region is particularly important. However, in the general wet chemical analysis, Y ₂
Although the average concentration of O ₃ can be obtained, the concentration distribution in the minute region cannot be known. Therefore, for the ceramic coating of the present invention, the concentration distribution in the minute areas of the ceramic coating is measured by X-ray diffraction, EPMA, molecular electron microscopy, etc., and the concentration distribution in these minute areas is within the above range. Here, since the accuracy of the distribution density increases as the area to be measured becomes smaller, the density when specified in the measurement area with a diameter of 5 μm or less is within the range of the distribution defined by the present invention. preferable. More preferably, it is desirable that the concentration obtained in a minute region having a diameter of 1 μm or less is within the range of the distribution specified.

The ceramic film of the present invention can be applied to a film formed by a thermal spraying method or chemical vapor deposition, but is preferably formed by a physical vapor deposition method. For example, when the ceramic target material is evaporated by irradiation with an electron beam and heated to cover the member, a film is formed by the evaporated clusters, so that the structure of the film becomes a crystal composed of minute columnar crystals and a Y region of a minute region is formed. ₂ O ₃ concentration distribution becomes uniform. In this case, the amount of Y ₂ O ₃ in the ceramic coating is 10% as compared with Y ₂ O ₃ in the ceramic target material.
The amount decreased by several percent. FIG. 8 shows a part of the result of investigating this relationship. That is, from these results, the stabilizer concentration range 3 to 18 in the minute region of the ceramic coating layer
Ceramic target material satisfying wt% is 5 to 20w
It has been found that those having a stabilizer concentration range of t% are suitable.

Since the ceramic target material is formed by sintering the raw material powder, it is desirable to uniformly contain the stabilizer from the stage of the raw material powder. When the raw material powder is sintered, the crystal grain size of the ceramic target material has a certain distribution,
The ceramic target material in the present invention is 0.1 to 2
It has a particle size distribution of μm and the concentration distribution of Y ₂ O ₃ in the crystal grains is 5 to 20 wt%. By using such a target material, the ceramic coating formed by the physical vapor deposition method has an average concentration of Y ₂ O ₃ of 5 to 1
It can be in the range of 5 wt%. In addition, the concentration distribution of Y ₂ O ₃ in the minute region in the ceramic coating is set to ₃ to 1
It can be contained within the range of 8 wt%.

The first embodiment of the present invention will be described below.

The base material is Ni-based Inconel-738.
The heat shield coating was applied to the blade surface 23 and the blade surface side of the shroud 24 for the gas turbine blade as shown in FIG.

FIG. 6 is a view showing a vertical cross section of the coating according to the present invention. The blade base material 25 is coated with a bonding layer 26 made of MCrAlY, and a ceramic layer 27 is formed thereon.

This film is formed by first degreasing and cleaning the blade,
Blasted using alumina grid, 10% Ni-2
An alloy powder consisting of 5% Cr-7% Al-0.6% Y and the balance Co was sprayed using Ar-He plasma in an Ar atmosphere of 20 Torr to obtain a film excellent in high temperature oxidation and high temperature corrosion. The thickness of the film is uniform and is about 150 μm.

Next, 8 is formed on the CoNiCrAlY layer.
% To form a _{Y 2 O} 3 -ZrO 2 ceramic layer. That is, first, in the vacuum chamber 1, the gas turbine blade was mounted on the base material driving device 11, and the crucible 3 was mounted with the 8% Y ₂ O ₃ —ZrO ₂ fuel binder. After that, the inside of the vacuum chamber 1 was evacuated to the order of 10 ⁻⁴ Pa, and then the blade was rotated and tilted while being heated to several 100 ° C., and 8% Y ₂ O ₃ —ZrO ₂ ceramic material was evaporated by an electron beam. At this time, scanning of the electron beam was controlled in order to keep the film formation rate almost constant. In addition, in order to form a ceramic film with excellent adhesion strength and stoichiometric composition, the evaporated ceramic material is ionized, oxygen is introduced as a reaction gas, and the blade is heated to several hundreds of degrees Celsius A voltage was applied to form a film. The obtained film thickness was about 100 μm.

The blade thus manufactured was subjected to an oxidation test for comparison with the conventional product. The conventional product uses the same blade material and coating material as described above, and both coatings are manufactured by atmospheric plasma spraying, and the coating thicknesses are also the same.
A cross-sectional view of this conventional coating is shown in FIG. In this conventional product, as in FIG. 6, the blade base material 25 is covered with the coupling layer 26 made of MCrAlY, and the ceramic layer 27 is formed thereon. However, many pores are present in the coating layer in the conventional product.

The oxidation test was conducted at 900 ° C., 1000 ° C., 11
After maintaining in the air atmosphere at a temperature of 00 ° C for 120 hours, the state of cracking and peeling of the ceramic film is observed.
Table 1 shows the oxidation test results.

[0051]

[Table 1] That is, in the conventional thermal barrier coating, the 8% Y ₂ O ₃ —ZrO ₂ ceramic layer peeled off at 1000 ° C. or higher (holding for 120 hours). On the other hand, the thermal barrier coating according to the present invention did not show any damage in appearance.

Next, a thermal cycle test was conducted using a test piece manufactured in the same manner as above.

This test was conducted at 1000 ° C. × 3 in the air atmosphere.
It is held by heating for 0 minutes and then in water at 20 to 25 ° C. for 5 minutes. By setting this as one cycle, the number of heat cycles until the heat shield coating layer is peeled off is obtained. Table 2
The results are shown in.

[0054]

[Table 2] As shown in Table 2, the conventional thermal barrier coating has 90 to 1
Delamination of the ceramic layer occurred after 00 thermal cycles. On the other hand, in the case of the present invention, peeling occurred in 220 to 310 times, and the number of thermal cycles of 2 to 3 times was obtained.

As described above, it can be confirmed that the heat-shielding coating according to the present invention is excellent in high-temperature oxidation resistance and thermal shock resistance as compared with the conventional heat-shielding coating.

Next, a second specific example of the present invention will be described.

In order to understand the influence of the stabilizer concentration, examples according to the present invention and comparative examples according to the conventional method will be described.
In the example according to the present invention, an alloy powder consisting of 23% Co-21% Cr-9% Al-0.7% Y balance Ni was used as a bonding layer on a SUS304 base material under reduced pressure plasma spraying to stabilize this bonding phase. Using a ceramic target material in which the composition of the agent Y ₂ O ₃ is changed, a ceramic coating layer is formed by physical vapor deposition.
The thickness is about 50 μm. As a result of measuring the ceramic coating layer thus obtained by X-ray diffraction, the crystal was found to be tetragonal Z
The rO ₂ was 90% or more.

In the comparative example, a bonding layer having the same composition as that of the example was formed by atmospheric plasma spraying, and a ceramic coating layer was formed by atmospheric plasma spraying to a thickness of about 150 μm.

A part of each of the ceramic coating layers obtained in the above-described Examples and Comparative Examples was taken, the average concentration of the stabilizer was examined by wet analysis, and the concentration of the stabilizer in the micro area with a diameter of 1 μm was measured. The EPMA was measured at 50 points and the concentration was examined.

The results are shown in Tables 3 and 4.

Next, each of the samples according to the examples and comparative examples was held in an air atmosphere at 200 ° C. (steam partial pressure = 0.02 atm) and steam at 15 atm for 200 hours, respectively, and thereafter, the ceramic coating layer. The crystal structure of was investigated by X-ray diffraction, and the phase transition amount was evaluated for each.

The results of these evaluations are also shown in Tables 3 and 4.

[0063]

[Table 3]

[0064]

[Table 4] As is clear from Tables 3 and 4, the ceramic coating layers according to the examples all have an average concentration in the range of 5 to 15 wt% and a concentration distribution in a minute region of 3%.
It falls within the range of ~ 18 wt%. On the other hand, the ceramic coating layer according to the comparative example has an average density of 5
Although it is within the range of ˜15 wt%, it can be seen that the concentration in the minute region has a region of 3 wt% or less, and the concentration distribution varies widely.

Further, it can be seen that the ceramic coating layers according to the examples are prevented from undergoing phase transition even after the treatment in steam and have excellent resistance to steam corrosion. It can be seen that each ceramic coating layer according to the comparative example undergoes a large amount of phase transition after the treatment in water vapor, and the durability is significantly reduced due to water vapor corrosion.

Based on these results, Ni was used as the base material.
A base Inconel-738 was used and the surface was subjected to a thermal barrier coating.

This film is formed by first degreasing and cleaning the blade, and then
Blasted using alumina grid, 23% Co-2
An alloy powder consisting of 1% Cr-9% Al-0.7% Y balance Ni was sprayed using an Ar atmosphere hand Ar-He plasma of 20 Torr to obtain a film excellent in high temperature oxidation and high temperature corrosion. The thickness of the film is uniform and is about 150 μm.

Next, an 8% Y ₂ O ₃ --ZrO ₂ zirconia coating layer was formed on the Ni Co Cr Al Y layer. In this formation, first, a gas turbine blade is attached to the substrate driving device 9 in the vacuum chamber 1, and the zirconia coating layer is 8% Y ₂ O ₃ —ZrO ₂ as the ceramic target material 3 in the crucible 4. 9.5%
The Y ₂ O ₃ -ZrO ₂ target material is mounted.

After that, the inside of the vacuum chamber 1 was evacuated to the level of 10 ⁻⁴ Pa, and then the blade was rotated and tilted while being heated to several 100 ° C., and was electron beam irradiated with 9.5% Y ₂ O ₃ —Z.
The rO ₂ target material was evaporated. At this time, the scanning of the electron beam was controlled in order to keep the film formation rate almost constant. In order to form a ceramic film having excellent adhesion strength and stoichiometric composition, oxygen was introduced as a reaction gas, and the blade was heated to several 100 ° C. to form the film. The obtained film thickness was about 100 μm.

The blade thus manufactured was subjected to composition analysis, X-ray diffraction and oxidation test for comparison with the conventional product. The conventional product uses the same blade material and coating material as described above, and both coatings are manufactured by atmospheric plasma spraying, and the coating thicknesses are the same.

Table 5 shows the results of micro analysis and Table 6 shows the results of X-ray diffraction.

[0072]

[Table 5]

[0073]

[Table 6] That is, the conventional thermal barrier coating has a large variation in microscopic composition, and monoclinic zirconia is also present.
On the other hand, the thermal barrier coating according to the present invention has a small variation in composition and has only tetragonal crystals.

Next, an oxidation test was conducted. The test is 900 ℃,
After being kept in the air atmosphere at a temperature of 1000 ° C. and 1100 ° C. for 120 hours, the state of cracking and peeling of the ceramic coating is observed, and Table 7 shows the oxidation test results.

[0075]

[Table 7] That is, the conventional thermal barrier coatings are all 1000
The ceramic coating layer was peeled off at a temperature of not less than ° C (holding for 120 hours). On the other hand, the thermal barrier coating of the present invention did not show any damage in appearance.

Next, a thermal cycle test was conducted using a test piece manufactured as described above. This test is performed by heating and holding at 1000 ° C. for 30 minutes in the air atmosphere, and then 20-
Hold in water at 25 ° C for 5 minutes. This is set as one cycle, and the number of thermal cycles until the thermal barrier coating layer is peeled off is obtained. Table 8 shows the results.

[0077]

[Table 8] As shown in Table 8, the conventional heat-shielding coating is 79-1.
Delamination of the ceramic layer occurred after 05 thermal cycles.

On the other hand, according to the product of the present invention, 290 to 33
Peeling occurred at 5 times and the number of thermal cycles about 3 times was obtained.

As described above, it can be confirmed that the heat-shielding coating according to the present invention is excellent in high temperature oxidation resistance and thermal shock resistance as compared with the conventional heat-shielding coating.

[0080]

As described above, according to the present invention, Ni,
On the surface of a base material composed mainly of at least one of Co and Fe, and at least one of Cr and A of Ni and Co.
including l, Hf, Ta, Y, Si, Zr
A step of forming a bonding layer consisting of any one of them or a combination thereof, and CaO containing ZrO _{2 as} a main component.
And a step of evaporating and ionizing a ceramic made of any one of MgO and Y ₂ O ₃ or a combination thereof to coat the bonding layer of the above alloy with the ceramic. Etc., the film formation energy increases, and it has a strong directionality and a dense structure,
Excellent adhesion strength, capable of forming a ceramic coating with stoichiometric composition, stable for a long time,
It is possible to obtain a heat-shielding coating that is unlikely to crack or peel.

Moreover, the stabilizer concentration together with the average concentration,
By controlling the concentration distribution in the minute region, it is possible to provide a ceramic coating film having excellent mechanical strength and extremely excellent steam corrosion resistance.

Further, since the ceramic coating film is formed by the physical vapor deposition method using the ceramic target material in which the crystal grain size and the stabilizer concentration distribution are controlled, the stabilizer content of the ceramic coating layer has a microscopically uniform composition. And can be more stabilized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a ceramic coating device according to a manufacturing method of the present invention.

FIG. 2 is a control system diagram of an electron beam generator and an electron beam scanning device.

FIG. 3 is a diagram showing an example of crucible heating means.

4A, 4B, and 4C are views showing examples of a base material heating unit.

FIG. 5 is an external view of a gas turbine blade.

FIG. 6 is a cross-sectional view of a thermal barrier coating according to the present invention.

FIG. 7 is a cross-sectional view of a conventional thermal barrier coating.

FIG. 8 is a diagram showing the relationship between the Y ₂ O ₃ content of a zirconia target material and the Y ₂ O ₃ content of a coating film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 vacuum chamber 2 evacuation device 3 crucible 4 electron beam generator 5 electron beam scanning device 6 thermoelectron generator 7 thermoelectron accelerator 8 ionization current detector 9 film formation rate detector 11 substrate driving device 12 heat resistant alloy member 16 Gas flow rate control device 17 Crucible resistance heating device 25 Blade base material 26 Bonding layer 27 Ceramic layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location C23C 14/32 Z 8414-4K A 8414-4K (72) Inventor Michio Watanabe Tokyo Fuchu City Toshiba Town No. 1 at Fuchu Factory, Toshiba Co. (72) Inventor Akiko Yoshikura No. 1 at Toshiba Town, Fuchu City, Tokyo Inside Fuchu Factory, Toshiba Co., Ltd. (72) Keizo Honda Suehiro-cho, Tsurumi-ku, Yokohama 2-4, Toshiba Keihin Office

Claims (7)

[Claims] 1. A substrate containing at least one of Ni, Co and Fe containing Cr and Al on at least one of Ni, Co and Fe as a main component, and Hf and T.
a step of forming a bonding layer composed of any one of a, Y, Si and Zr or a combination thereof, and any one of CaO, MgO and Y ₂ O ₃ containing ZrO ₂ as a main component or a combination thereof. Evaporate a combination of ceramic materials
Ionizing and coating on the bonding layer of the above alloy. 2. The step of forming a bonding layer of the alloy comprises:
r, the He, comprising the step of plasma spraying in either one or 1 atm following atmosphere let them combined in H _2, N _2, the step of coating the ceramic comprises the steps of evaporating a ceramic material, thermal It has a step of ionizing the ceramic particles evaporated by an electron generator and a thermoelectron accelerator, a step of introducing a reaction gas, a step of heating the base material, and a step of applying a voltage to the base material. A method for producing a ceramic coating according to claim 1. 3. An electron beam current and an electron beam scan of an electron beam generator or a crucible resistance heating are controlled by a signal from one or both of a film forming rate detector and an ionization current detector. A method for producing a ceramic coating according to claim 1, characterized in that 4. The substrate is one of a substrate resistance heating device, a lamp heating device, a high frequency heating device, and an electron beam heating device.
The method for producing a ceramic coating according to claim 2, wherein the heating is performed by one or a combination thereof. 5. The ceramic coating is formed by physical vapor deposition, the coating contains 90% or more of tetragonal crystals, and the average concentration of the stabilizer Y ₂ O ₃ in the coating is in the range of 5 to 15 wt%, and The method for producing a ceramic coating according to claim 1, wherein the concentration in the minute region is distributed between 3 and 18 wt%. 6. The method for producing a ceramic coating according to claim 1, wherein the ceramic material for evaporating the ceramic particles has an average concentration of the stabilizer Y ₂ O ₃ in the range of 5 to 20 wt%. 7. The ceramic material has a grain size of 0.1 to 2 .mu.m.
The method for producing a ceramic coating according to claim 1, wherein the method has a particle size distribution of m and the Y ₂ O ₃ content in the crystal grains is 5 to 20 wt%.