JP3394833B2 - Method of manufacturing thermal barrier coating member - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal barrier coating member formed by forming a thermal barrier coating layer made of ceramics on a surface of a base material made of a heat-resistant alloy, and a method for producing the same.

[0002]

2. Description of the Related Art In order to improve the efficiency of a gas turbine plant for power generation, increasing the gas turbine inlet temperature to 1300 ° C. or higher has become an essential issue. In order to solve this problem, efforts are being made to increase the heat resistant temperature of the moving blades and the stationary blades exposed to high temperature gas, and as a method therefor, development of a material, that is, a heat resistant alloy is urgently needed. However, the heat-resistant temperature obtained with the heat-resistant alloy is limited to 850 ° C. with the current technology, and in view of high-temperature oxidation and high-temperature corrosion, this type of heat-resistant alloy is not sufficient.

Therefore, in place of this heat-resistant alloy, development of a ceramic material having a higher heat-resistant temperature is under way.
However, when such ceramic materials are used for the moving blades and stationary blades of a gas turbine, their toughness is insufficient for application to rotating rotor blades, and their application to stationary blades also has impact resistance to incoming particles. However, there is a problem in that it has not been applied yet.

Then, in order to deal with the problem of increasing the gas turbine inlet temperature, another method has been attracting attention. This is a method of coating the surface of the member with a ceramic material having a low thermal conductivity.
rmal Barrier Coating, TBC
Called. )It is called. This TBC has a function of suppressing a substantial temperature rise of the alloy-based material, and the heat shielding effect by this is generally considered to be about 50 to 100 ° C.

[0005]

By the way, the TBC has so far been applied to a combustor of a gas turbine plant only to some extent, and not applied to a moving blade. Ceramics having heat-shielding properties have greatly different physical properties from heat-resistant alloys, and it is particularly difficult to apply them to moving blades, etc., where peeling is a problem. In order to increase the reliability of the TBC-treated member, a more reliable method must be used.

A method found from this point of view is to form a bond layer made of a metal material between the ceramic layer and the heat resistant alloy. This bond layer contains Ni or Co as a main component, and contains Cr, Al, and Y, Hf, and T to alleviate the difference in physical properties between the alloy of the base material and the ceramics layer.
In many cases, a bond layer made of a so-called MCrAlY-based alloy to which a, Si or the like is appropriately added is formed on the surface of the base material.

However, under a high-temperature use environment, oxygen that permeates the ceramic layer diffuses into the bond layer, and Al and Cr on the surface of the bond layer oxidize to cause Al ₂ O ₃ and Cr ₂ O.
₃ etc. are generated and this may become a new source of thermal stress. For this reason, the adhesion of the thermal barrier coating layer is significantly weakened and peeling occurs.

In order to improve the adhesion, a ceramic layer is formed on the ceramic layer by a physical vapor deposition method (Physical Vapor Depo).
position, hereinafter referred to as PVD method. It is considered that the TBC member is manufactured by forming the TBC member.
When the ceramic layer is formed by PVD, the adhesion to the base material is remarkably increased, which is considered to be an effective method. However, in PVD, when a ceramic layer is formed on the surface of the bond layer in order to grow in a direction perpendicular to the surface of the base material to be formed, the film structure becomes a crystal structure that grows randomly along the shape of the surface of the bond layer. For this reason, the adhesiveness in the ceramics layer is reduced, and the thermal barrier coating layer cannot be effectively functioned to prolong its life.

Therefore, an object of the present invention is to prevent generation of oxides at the interface between the ceramic layer and the bond layer in a turbine constituent member such as a moving blade used under high temperature gas. A thermal coating member and a method for manufacturing the same are provided.

[0010]

According to the manufacturing method of the present invention, a base material of a heat-resistant alloy having Ni or Co as a main component contains at least one of Ni and Co as a main component and further contains Cr and Al. by spraying the alloy to form a bond layer, forms the shape of the barrier layer is irradiated with a laser beam in an atmosphere containing oxygen to the surface of the bond layer further composed mainly of ZrO ₂ on the surface of the barrier layer It is characterized in that a thermal barrier coating layer is formed by depositing ceramics.

[0011]

[0012]

Although the temperature of the working gas of the gas turbine is gradually increasing, it is well known that the rate of oxide formation increases remarkably with the increase of the working gas temperature. In particular, when the temperature is 1000 ° C. or higher, the oxide formed at the interface between the bond layer and the ceramic layer is easily separated because both Al and Cr, which have a high oxide generation rate in MCrAlY, generate the oxide. .

In order to avoid this, the inventors conducted a test and obtained the following findings. That is, when the surface of the bond layer is locally melted and solidified, oxygen permeating through the ceramic layer is significantly reduced. It is assumed that this is because Al is selectively oxidized to form a dense layer of Al ₂ O _{3 on the} surface.

A bond layer made of MCrAlY was formed on the surface of the base material, laser treatment was performed in an atmosphere containing oxygen to form a barrier layer, and then a ceramic layer was formed by PVD on the surface of the bond life test. The results are shown in Table 1.
Is shown in. In this test, the TBC surface was heated by a burner, kept at a temperature of 1200 ° C for 40 minutes, and then heated at 160 ° C.
The operation of cooling to ° C was set as one cycle, and the number of cycles until the ceramic layer was peeled off was examined for each test piece.

[0015]

[Table 1] Test piece No. Nos. 1 to 3 show those produced by the method of the present invention. Reference numeral 4 shows a test piece in which both the bond layer and the ceramics layer prepared for comparison were formed by plasma spraying in the atmosphere. N
o. In No. 4, peeling occurred in 513 to 850 cycles. On the other hand, according to the present invention, 1865 to 21
Peeling occurred after 63 cycles.

The dense barrier layer made of Al ₂ O ₃ found in the present invention has a function of blocking oxygen that permeates the ceramic layer and preventing the bond layer from being oxidized during the operation of the gas turbine. Therefore, the peel resistance can be improved.

Further, a smooth surface can be obtained by performing the laser treatment, and it becomes possible to form the ceramic thermal barrier coating layer formed by PVD into columnar crystals that grow in the direction perpendicular to the bond layer. MC used for bond layer
The rAlY alloy preferably has a high Al concentration in order to enhance the oxidation resistance, but in consideration of matching with the base material, it is preferable to use a material having a low Al concentration and high ductility. Therefore, in the present invention, the surface of the bond layer is subjected to Al addition treatment. As a result, only the surface part is A
It is possible to increase the 1 concentration and preferentially generate Al ₂ O ₃ during laser processing. In addition, MCr with high ductility on the substrate side
By using AlY, Al ₂ O ₃ can be preferentially generated during laser processing.

[0018]

EXAMPLE An example in which the present invention is applied to a moving blade of a gas turbine will be described. In FIG. 2, a rotor blade 1 made of a heat-resistant alloy
In No. 1, a thermal barrier coating layer 12 made of a ceramics layer is formed in the gas passage portion in advance by finishing the shape as shown in the drawing by machining or the like. This embodiment will be described in more detail with reference to FIG. 1, which schematically shows a cross section of the thermal barrier coating layer 12.

First, as shown in FIG. 1A, a bond layer 14 of MCrAlY is formed on the surface of a base material 13 made of a heat-resistant alloy containing Ni or Co as a main component, and then, as shown in FIG.
As shown in (b), the surface of the bond layer 14 is melted by laser treatment in an atmosphere containing oxygen, and the melt-treated layer 15 is formed.
And Further, on the surface of the melt-processed layer 15, as shown in FIG.
As shown in (c), a ceramics layer 16 having a predetermined thickness is formed as a thermal barrier coating layer.

The above steps will be described in more detail.
The bond layer 14 made of MCrAlY in FIG. 1A is formed to a thickness of 10 to 200 .mu.m by the low pressure plasma spraying method. This low pressure plasma spraying method has a high adhesion strength to the base material 13 and is very desirable as a film forming method. However, if not so, the film is formed by an atmospheric plasma spraying method or a high speed flame spraying method.

Next, in order to melt the surface of the bond layer 14 of FIG. 1 (b) by laser processing, the processing speed is 50 to 1500 mm.
Irradiate with laser light while keeping at / min. Although the laser light is not limited to this, for example, a CO ₂ laser or a YAG laser is used, and the output is maintained at 1 to 10 KW. in this case,
As shown in FIG. 3, the laser light 22 from the laser oscillator 21
Is irradiated onto the surface of the board layer 14 by defocusing it by the condenser lens 23. The focal length of the condenser lens is 12
7 mm, 190.5 mm, 254 mm, 381 mm and 508 mm, and the laser beam diameter on the surface of the bond layer 14 is 5 to 3
Hold at 5 mm. Next, the melt processing layer 15 of FIG.
The ceramic coating device is used to form the ceramic layer 16 on the surface. That is, as shown in FIG. 4, this ceramic coating apparatus is composed of a vacuum chamber 24 for coating processing, a vacuum exhaust apparatus 25 composed of a diffusion pump and an oil diffusion pump, and a control unit and a power supply unit (not shown).

A crucible 27 for mounting a ceramic material 26 is arranged in the lower part of the vacuum chamber 24, and an electron beam generator 28 for melting and evaporating the ceramic material 26 is disposed below the crucible 27. , Crucible 2
An electron beam scanning device 29 is provided on one side of each of the seven. On the other hand, the motor 30 is installed in the upper part of the vacuum chamber 21.
The base material drive device 31 driven by is provided, and the base material 32 is attached to the end portion of the base material drive device 31.

In order to form the ceramic layer 16, the ceramic material 26 is first filled in the crucible 27, and the substrate 32 is formed.
Is mounted on the substrate driving device 31. Next, the vacuum exhaust device 2
5 is operated to maintain the inside of the vacuum chamber 24 at a vacuum degree of 10 ^-2 to 10 ^-4 Pa. Next, the electron beam generator 28 irradiates the ceramic material 26 with an electron beam to melt the surface thereof. At this time, the electron beam current is controlled so that the predetermined evaporation rate is maintained with the surface always melted,
Further, the ceramic layer 16 is formed on the surface of the melt-processed layer 15 by scanning with an electron beam.

The ceramics formed here are ZrO ₂
8% by weight of ZrO ₂
8% yttria partially stabilized zirconia partially stabilized with _{Y 2 O 2 (8wt% Y} 2 O 3 -ZrO 2) is desirable. In the case where this is not the case, for example, zirconia whose amount of yttria added is changed, zirconia partially stabilized with ceria, calcia or the like may be used.

When the laser treatment is applied to the surface of the bond layer 14, the surface of the bond layer 14 having irregularities is melted and smoothed as shown in FIG. 1 (b). Therefore, the surface of the bond layer 14 is scattered in the sprayed layer. The fine porosity disappears, and the surface is dense Al ₂ O
_A barrier layer consisting of ₃ is formed. The barrier layer made of Al ₂ O ₃ can block oxygen that permeates the thermal barrier coating layer 12 during operation, and can prevent the bond layer 14 from being oxidized.

The ceramic layer formed by the vapor deposition method is greatly affected by the surface properties of the formed film. However, by finishing the surface of the base material in advance, the base material 1
The columnar ceramic layer 16 can be formed in a direction perpendicular to the direction 3. The thickness of this ceramic layer 16 is 50
˜400 μm is desirable.

Further, another embodiment of the present invention will be described with reference to FIG. In this embodiment, an Al addition process is performed together with the bond layer 14 made of MCrAlY. That is, in this embodiment, after the bond layer 14 is formed, the Al addition layer 17 is formed as shown in FIG. As a result, Al ₂ O ₃
The formation of the layer made of can be made more reliable. Al
As a method of forming the additional layer 17, it is desirable to use a pack process capable of forming an Al additional layer of 2 to 50 μm on the surface.

An embodiment different from the one described above will be described with reference to FIG. In this embodiment, a plurality of bond layers are formed instead of the single bond layer 14 made of MCrAlY. That is, the first layer close to the base material 13 has a low Al concentration, for example, the inner bond layer 18 made of MCrAlY of 3% or more and less than 6%, and the second layer has a high Al concentration, for example, 6% or more and 20% or less. The outer bond layer 19 is made of MCrAlY. The inner bond layer 18 close to the base material 13 keeps the Al concentration low in order to maintain ductility equivalent to that of the base material 13, while the outer bond layer 19 is kept.
Is A in order to easily form Al ₂ O ₃ having excellent corrosion resistance.
l Increase the concentration. In the case of such a multi-layered bond layer, the TBC and the base material on which the TBC is applied are well matched, and the peel resistance can be more reliably improved.

[0029]

As described above, according to the present invention, since the barrier layer made of an oxide is formed on the surface of the bond layer, oxygen reaches the bond layer even in an environment exposed to a high temperature working gas such as a gas turbine. It can be surely prevented from doing. In addition, the surface of the bond layer contains an atmosphere containing oxygen.
A smooth barrier layer by irradiating laser light in the atmosphere
Is obtained, and ceramics are vapor-deposited on this
By forming a wing layer, columnar crystals are formed in the direction perpendicular to the substrate.
The thermal barrier coating layer can be formed. Therefore, according to the present invention, it is possible to prevent the thermal barrier coating layer from peeling off due to the oxide generated at the interface between the bond layer and the thermal barrier coating layer made of ceramics, and to extend the service time of the moving blade etc. greatly. Will be possible.

[Brief description of drawings]

1A, 1B, and 1C are process diagrams showing a method for manufacturing a thermal barrier coating member according to the present invention.

FIG. 2 is a perspective view of a moving blade that is an application example of a thermal barrier coating member.

FIG. 3 is a diagram for explaining a laser processing process according to the present invention.

FIG. 4 is a configuration diagram showing a ceramic coating device used in the present invention.

FIG. 5 is a process drawing showing another embodiment of the present invention.

FIG. 6 is a process drawing showing another embodiment of the present invention.

[Explanation of symbols]

11 moving blade 12 Thermal barrier coating layer 13 Base material 14, 18, 19 Bond layer 15 Molten layer 16 Ceramics layer 17 Al additional layer 24 vacuum chamber 27 crucibles 31 Substrate driving device

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuhiro Yasuda 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center (72) Inventor Takanari Okamura 2 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa 4 Stock Company Toshiba Keihin Works (72) Inventor Kazuhide Matsumoto 1st Toshiba Town, Fuchu City, Tokyo Inside Toshiba Fuchu Factory (72) Inventor Yoshinobu Makino 4 shares of 2 Suehiro Town, Tsurumi Ward, Yokohama City, Kanagawa Prefecture (56) Reference JP-A-8-246901 (JP, A) JP-A-8-225959 (JP, A) JP-A-8-225958 (JP, A) JP-A-8-135469 (JP, A) JP 8-85883 (JP, A) JP 8-67990 (JP, A) JP 7-54603 (JP, A) JP 61-32392 (JP, B2) (JP, A) 58) Fields surveyed (In t.Cl. ⁷ , DB name) C23C 28/00-30/00 F01D 5/28 F01D 9/02

Claims (3)

(57) [Claims] 1. A bond layer is formed by thermally spraying an alloy containing at least one of Ni and Co as a main component and further containing Cr and Al onto a base material of a heat-resistant alloy having one of Ni and Co as a main component. , the shape formed the barrier layer is irradiated with a laser beam in an atmosphere containing oxygen to the surface of the bond layer
A method of manufacturing a thermal barrier coating member, characterized in that a thermal barrier coating layer is formed by vapor-depositing ceramics containing ZrO ₂ as a main component on the surface of the barrier layer. 2. The method for manufacturing a thermal barrier coating member according to claim 1 , wherein an Al addition layer is formed on the surface of the bond layer by a pack treatment prior to the irradiation of the laser beam . 3. An inner bond layer is formed by spraying an alloy containing at least one of Ni and Co as main components, and further containing Cr and low concentration Al instead of the bond layer formed on the base material. At the same time, an outer bond layer is formed on the bond layer by spraying an alloy containing at least one of Ni and Co as a main component and further containing Cr and high concentration Al. A method for manufacturing a heat-coated member.