JP2941548B2 - Moving and stationary blade surface layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface layer of a moving and stationary blade having high corrosion resistance applied to a gas turbine or the like.

[0002]

2. Description of the Related Art The temperature of a gas at the inlet of a recent industrial gas turbine of high efficiency represented by a combined cycle plant has risen significantly to 1300 ° C. or more. The heat-resistant alloy used for the moving and stationary blades exposed to such a high-temperature gas has been vigorously researched and developed, and its allowable use temperature has been increasing year by year.
About 900 ° C. For this reason, a thin internal air cooling blade is used in an actual gas turbine.

On the other hand, the fuel used is LNG, by-product gas or heavy oil, and recently, the use of coal as a liquefied or gasified coal has been studied. Therefore, the purpose is to prevent high-temperature oxidation and high-temperature corrosion of air cooling blades. NiCoCrAlY or CoC by thermal spraying (hereinafter referred to as VPS) with low pressure plasma
Coating of a corrosion-resistant alloy such as rAlY is performed.

[0004]

In a high temperature gas turbine, the moving and stationary blades that come into direct contact with the combustion gas increase in oxidation rate and corrosion rate as the gas temperature increases.
Even when the above-mentioned corrosion-resistant coating is applied, a situation has appeared where significant corrosion damage is caused when a high-temperature corrosive component is introduced from fuel or combustion air. For this reason, the appearance of moving and stationary blades having more excellent high-temperature corrosion resistance is desired.

SUMMARY OF THE INVENTION The present invention aims to provide a surface layer of a moving and stationary blade excellent in high-temperature corrosion resistance in accordance with the above-mentioned state of the art and the above-mentioned demand.

[0006]

The present invention provides (1) 20 to 2
5wt% Cr, 6-8wt% Al, 0.5-1wt% Y
NiCrAlY or CoNiCrAlY (Co /
CoCrAlY or CoNiCrAlY (Co / Ni ratio is arbitrary) containing a first layer coated with low-pressure plasma spraying on a first layer coated with low-pressure plasma spraying and containing 30% by weight or more of Al, 0.5% by weight or more of Y and 0.5 to 1% by weight of Y. ) Are alternately formed with a second layer coated with low-pressure plasma spraying.

(2) 20 to 25 wt% Cr, 6 to 8 wt%
% Al, a first layer coated with NiCrAlY or CoNiCrAlY (Co / Ni ratio is arbitrary) containing 0.5 to 1 wt% Y by low pressure plasma spraying, 1 to 5 wt% P
t, 20 to 25 wt% Cr, 6 to 8 wt% Al, 0.5
NiCrAlPtY or CoNiC containing １1 wt% Y
Second layer coated with rAlPtY (Co / Ni ratio is arbitrary) by low pressure plasma spraying, C of 30 wt% or more
r: NiCrAlY or CoNiCrAlY (Co / Ni ratio is arbitrary) containing 10 wt% or more of Al and 0.5 to 1 wt% of Y by low pressure plasma spraying.
The moving and stationary blade surface layer consisting of layers. It is.

That is, in both the first invention and the second invention, a high-corrosion-resistant surface-treated moving / static vane having a surface treatment having the following characteristics is mainly intended for use in a high-temperature gas turbine burning inferior fuel. is there.

(1) The first invention will be described in more detail with reference to FIG. 20 to 50 μm for moving and stationary blades to be processed
20 ~ 25wt% Cr, 6 ~
NiCrAl containing 8 wt% Al and 0.5-1 wt% Y
Y or CoNiCrAlY (remainder: Ni or Ni, C
o, Co / Ni is arbitrary) is coated by low pressure plasma spraying (VPS). Continue, 30
wt% or more of Cr, 10 wt% or more of Al and 0.5
CoCrAlY or CoNi containing ~ 1.0 wt% Y
The second layer 2 made of CrAlY (remainder: Ni or Ni, Co, Co / Ni is optional) is VPS having a thickness of 20 to 50 μm.
Perform processing. The steps of forming the first layer 1 and the second layer 2 are repeated according to the degree of corrosion resistance imparted (for example, when repeated three times, the total film thickness becomes 120 to 300 μm). VPS above
After the treatment, a predetermined heat diffusion treatment is performed to obtain a moving / static blade having the highly corrosion-resistant surface treatment layer of the first invention.

(2) The second invention will be described in further detail with reference to FIG. 20 to 50 μm for moving and stationary blades to be processed
20 ~ 25wt% Cr, 6 ~
NiCrAl containing 8 wt% Al and 0.5-1 wt% Y
Y or CoNiCrAlY (remainder: Ni or Ni, C
o, Co / Ni is arbitrary) is coated by low pressure plasma spraying (VPS). Without removing the blades or vanes from the spray chamber,
wt% Pt, 20 to 25 wt% Cr, 6 to 8 wt% A
1, NiCrAlPtY or CoNiCrAlPtY containing 0.5 to 1 wt% Y (remainder: Ni or Ni, Co,
Co / Ni is optional).
Spray ~ 20 µm. Furthermore, 30 wt% or more of Cr,
Co containing 10 wt% or more of Al and 0.5 to 1 wt% of Y
CrAlY or CoNiCrAlY (remainder: Co or C
o, Ni and Co / Ni are optional).
After processing with a VPS with a target thickness of ~ 300 µm, it is taken out of the thermal spray chamber and subjected to a predetermined heat treatment, whereby the second
A moving / static blade having the highly corrosion-resistant surface treatment layer of the invention can be obtained.

[0011]

(1) Function of the first invention 20 to 25 wt% C sprayed as the first layer and the intermediate layer
r, NiCrAlY or CoNiCrAlY containing 6 to 8 wt% Al and 0.5 to 1.0 wt% Y has excellent corrosion resistance and adhesion to the material to be treated (base material), and the treated layer is peeled off at the time of using at a high temperature or starting and stopping. Or cracking is prevented. Also, 30w sprayed as a surface layer and an intermediate layer
at least t% Cr, at least 10 wt% Al, 0.5-1.
CoCrAlY or CoNiCrAl containing 0 wt% Y
Y exhibits excellent high-temperature corrosion resistance due to its high Cr and Al contents.

[0012] Only CoCrAlY or CoNiCrAlY containing 30 wt% or more of Cr, 10 wt% or more of Al, and 0.5 to 1.0 wt% of Y has a slight difficulty in adhesion to a material to be processed (base material). Or cracks may occur during use or during use, but 20 to 25 wt% Cr, 6 to 8
NiCrA containing wt% Al and 0.5-1.0 wt% Y
Combination with 1Y or CoNiCrAlY can prevent peeling and cracking. In addition, by performing a multilayer treatment of an alloy containing high Cr and Al, Cr and Al diffuse into the material to be treated with use at a high temperature, and Cr and
It is possible to prevent the Al concentration from decreasing.

[0013] MCrAlY alloy (M = Co, Ni, Fe
Are famous as high-temperature corrosion-resistant alloys, but contain a large amount of Cr and Al, are poor in ductility, and have poor mechanical strength. Therefore, they are mainly used as surface treatment materials by thermal spraying or ion plating. The corrosion resistance of alloys based on Ni or Co depends on the content of Cr or Al, for example, according to Lrwis-Smith et al.
Shown as equivalents. Chromium equivalent =% Cr + 0.7 (% Al + 1.5Ti)

As described above, as the content of Cr and Al in the alloy in a certain range (for example, Cr ≒ 50 wt%, Al ≒ 20 wt%) increases, the corrosion resistance improves. However, when the Cr and Al increase, the ductility and strength of the coating film also deteriorate. Insufficient, cracks and peeling are likely to occur. Therefore, the practical upper limits of the amounts of Cr and Al in the coating film are about 35 wt% and 15 wt%, respectively.

Further, the addition of Y improves the adhesion of the oxide film, but the effect is not particularly noticeable at 1 wt% or more, and a large amount impairs the corrosion resistance.

According to the above analysis, in the first invention, the N in the first layer
Although the practical upper limit of Cr in iCrAlY or CoNiCrAlY is 35 wt%, the upper limit is 25 wt%, and the practical upper limit of Al is 15 wt%, but the upper limit is 8 wt%. Cr: 20 wt%
, Al: less than 6 wt%, there was no effect of improving corrosion resistance. As a result of the above analysis, Y is set to a lower limit of 0.5 wt% at which the effect of improving the adhesion is obtained, and 1 w which does not impair the corrosion resistance.
t% or less.

Further, the second layer of CoCrAlY of the first invention is provided.
Alternatively, the contents of Cr, Al, and Y in CoNiCrAlY are also certified based on the above analysis.

(2) Function of the Second Invention C of 30 wt% or more treated as the final layer (third layer)
r, CoCrAlY or CoNiCrAlY containing 10 wt% or more of Al and 0.5 to 1 wt% of Y has high Cr,
Exhibits excellent high-temperature corrosion resistance due to the Al content. NiCr containing Pt treated as an intermediate layer (second layer)
AlPtY or CoNiCrAlPtY exhibits better corrosion resistance than Pt, and also acts as a diffusion barrier to prevent Pt from being concentrated due to the use of high temperature to diffuse Cr and Al in the surface layer and reduce the concentration thereof. Furthermore, NiCrAlY or CoN sprayed on the wing material surface as the first layer
Since iCrAlY is sufficiently diffused into the blade material by the thermal diffusion treatment and has high flexibility, it is possible to prevent the surface treatment layer from peeling off or cracking due to use at a high temperature or starting and stopping.

In the second invention, the C of the first to third layers is C
The reasons for limiting the contents of r, Al, and Y are the same as those described in the first invention. The reason why Pt was contained in the second layer was P
This is because t contributes to the improvement of the corrosion resistance. However, at least 1 wt% is required to exhibit the corrosion resistance, and 5 wt%
Since no significant difference is recognized even if the above content is contained, Pt
Is limited to 1 to 5 wt%.

[0020]

Examples (Examples 1 to 4) Examples 1 to 4 according to the first invention of the present invention are shown in Table 3 below. In these examples, a stationary blade (ECY768) was used as a material to be processed. Blade (IN738L
Even when C) is used, the pretreatment-spraying-heat treatment process is exactly the same.

The pretreatment, thermal spraying, and heat treatment procedures are as follows. 〇 Pretreatment A blast treatment is performed with 16 to 36 mesh alumina particles for several minutes. (4) Low-pressure plasma spraying (PVS) The pre-processed workpiece was mounted in a low-pressure plasma spraying vessel, and spraying was performed as shown in Table 1 below.

[0022]

[Table 1] 〇Heat treatment Heat treatment was performed at 1190 ° C for 2 hours using a vacuum furnace.

The ECY76 used for the stationary blade and the moving blade
8, IN738LC has a composition as shown in Table 2 below.

[0024]

[Table 2]

Static blade material ECY768 and blade material IN738
Examples 1 to 4 shown in Table 3 below using LC as a base material, and Co
-20Ni-25Cr-8Al-0.5Y, Ni-25
Cr-6Al-0.5Y, Co-30Cr-12Al-
1Y, Co-20Ni-35Cr-15Al-0.5Y
With a diameter of 12 mm × length of 1 with a target of 200 μm thickness
A test piece was prepared by VPS spraying on a 00 mm round bar, and the adhesion and the corrosion resistance were compared in the following manner.

[0026]

[Table 3]

(1) Adhesion (Heat Shock Test) A test in which each test piece was heated to 1000 ° C., held for 15 minutes, and then put into water (room temperature) was repeated 5 times.
I put together. Examples 1-4 and Co-20Ni-2
5Cr-8Al-0.5Y, Ni-25Cr-6Al-
0.5Y was sound without any cracks or peeling after the test, whereas Co-30Cr-12Al-1Y was the first test, Co-20Ni-35Cr-15Al-
In 0.5Y, the crank was generated in the second test, and the treated layer was partially dropped after completion of the fifth test.

[0028]

[Table 4]

(2) Corrosion resistance (high temperature corrosion test) Using each test piece (base material ECY768), 80 wt% Na
_{A 2} SO ₄ -20 wt% V ₂ O ₅ synthetic ash application test was performed, and the results are summarized in Table 5. The corrosion amount of the embodiment according to the present invention is Co-20Ni-25Cr-8Al.
-0.5Y, 1/25 of Ni-25Cr-6Al-0.5Y
About 2 to 1/5, and Co-30Cr-12A
1-1Y and Co-20Ni-35Cr-15Al-0.
The amount of corrosion tended to be smaller than that of the 5Y single-layer treated product.

[0030]

[Table 5]

Examples 5 to 12 Examples 5 to 12 according to the second invention of the present invention are shown in Table 6 below. The object to be treated is a moving / static blade used in a normal gas turbine, and the respective materials are a typical moving blade material (IN738LC, Ni-base superalloy) and a stationary blade material (ECY).
768, Co-based alloy).

[0032]

[Table 6]

(1) Adhesion of surface treatment layer The final sprayed material of Examples 5 to 12 and ECY768, IN738LC were directly VPS sprayed with the final sprayed material as a test material (diameter 12 mm × length 100 mm). 100
After heating at 0 ° C and holding for 15 minutes, the thermal shock test of throwing into water (room temperature) was repeated 5 times, and the occurrence of cracks and peeling of each processing layer was confirmed for each cycle. In any of the sprayed materials, cracks occurred between 1 and 5 cycles, and some of the sprayed materials were peeled off. On the other hand, in Examples 5 to 12, all of the oxide scale was slightly adhered. No abnormalities were observed.

(2) Corrosion resistance of the surface treatment layer Examples 5 to 12 and the conventionally used CoNiCrAlY (C
o-20Ni-25Cr-8Al-0.5Y) and NiC
rAlY (Ni-20Cr-8Al-1.0Y) single-layer treated product, untreated material (ECY768, IN738LC) as a test material, 80 wt% Na ₂ SO ₄ -20 wt% V ₂ O
_{5 A} synthetic ash application test was performed, and the results are summarized in Table 7.

The amount of corrosion in each of the examples according to the present invention is 1/70 to 1/100 of the untreated material,
It was about 1/2 to 1/5 of rAlY and NiCrAlY, and it was confirmed that it had excellent corrosion resistance.

[0036]

[Table 7]

(3) Processed film thickness NiCrAlY or CoNiCr sprayed as the first layer
AlY aims to maintain adhesion as described above,
If the thickness is 20 μm or less, the entire treated surface may not be coated. Further, the thickness of about 50 μm sufficiently satisfies the purpose, and it has been confirmed that a thickness of 50 μm or more does not particularly contribute to adhesion. Furthermore, the second layer of Pt-containing NiC
With the use of rAlY or CoNiCrAlY, a Pt-enriched layer can be formed in a thickness of 10 to 20 μm in order to form a Pt-enriched layer, and coating of 20 μm or more increases the cost of Pt-containing expensive coating materials while improving corrosion resistance. Does not contribute. It is important that the third layer (outermost layer) has a film thickness of at least about 50 μm in order to exhibit corrosion resistance and have a life that can withstand actual use. However, when the film thickness exceeds 300 μm, cracks and the like may occur. It has been confirmed that film defects are likely to appear.

[0038]

According to the present invention, the operation of a gas turbine or the like
A surface layer having excellent adhesion and high corrosion resistance can be provided to the stationary blade.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment (first invention) of the present invention.

FIG. 2 is an explanatory view of another embodiment (second invention) of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Koji Takahashi 2-1-1, Shinhama, Araimachi, Takasago City, Hyogo Prefecture Inside the Takasago Works, Mitsubishi Heavy Industries, Ltd. No. 1 Mitsubishi Heavy Industries, Ltd. Takasago Machinery Works (58) Field surveyed (Int. Cl. ⁶ , DB name) C23C 4/08

Claims (2)

(57) [Claims] 1. 20 to 25 wt% Cr, 6 to 8 wt% A
1, NiCrAlY or Co containing 0.5 to 1 wt% Y
A first layer coated with NiCrAlY (Co / Ni ratio is arbitrary) by low pressure plasma spraying, 30 wt% or more of Cr, 10 wt% or more of Al, and 0.5 to 1 wt% of Y
CoCrAlY or CoNiCrAlY (Co /
A dynamic / static vane surface layer formed by alternately forming a second layer of (Ni ratio is arbitrary) coated by low-pressure plasma spraying. 2. 20 to 25 wt% Cr, 6 to 8 wt% A
1, NiCrAlY or Co containing 0.5 to 1 wt% Y
First layer coated with NiCrAlY (Co / Ni ratio is arbitrary) by low-pressure plasma spraying, 1 to 5 wt% Pt,
20-25 wt% Cr, 6-8 wt% Al, 0.5-1
NiCrAlPtY or CoNiCrA containing wt% Y
1PtY (Co / Ni ratio is arbitrary), low pressure plasma sprayed second layer, 30 wt% or more of Cr, 1
NiC containing 0 wt% or more of Al and 0.5 to 1 wt% of Y
A moving / static vane surface layer comprising a third layer coated with rAlY or CoNiCrAlY (Co / Ni ratio is arbitrary) by low-pressure plasma spraying.