JP3224716B2 - High temperature corrosion resistant surface treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart more excellent high temp. corrosion resistance to a metallic material base material by subjecting a metallic material base material for high temp. use successively coated with Pt or Ta, Cr base metal and an MCrAlY alloy to thermal diffusion treatment in a vacuum furnace or an Ar-H2 atmospheric furnace. SOLUTION: For example, an Fe base alloy A286, a Co base alloy ECY768 or an Ni base alloy IN738LC is used as a base material 1, which is plated with a Pt layer 2 hard to thermally diffuse 2 into 2 to 3μm objective thickness. Next, Cr plating 3 is executed into 10 to 15μm objective thickness. After that, it is coated with a Co-32wt.%Ni-21wt.%Cr-8wt.%Al-0.5wt.%Y alloy into 50μm objective thickness. Furthermore, Cr plating treatment and low pressure plasma spraying treatment of CoNiCrAlY alloy are the same as the above executed once more, and after that, thermal diffusion treatment at 1050 deg.C for 4hr is executed in a vacuum furnace (0.1 to 1.0mmHg).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for imparting high-temperature corrosion resistance to metal materials used at high temperatures, and more particularly to a high-temperature corrosion-resistant surface treatment method applied to moving and stationary blades of gas turbines.

[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, thinned internal air cooling blades are used in actual gas turbines. On the other hand, the fuels used are LNG, by-product gas and heavy oil, and recently, the use of liquefied or gasified coal has been studied. Therefore, low pressure plasma is used to prevent high temperature oxidation and high temperature corrosion of air cooling blades. A coating of a corrosion resistant alloy such as NiCoCrAlY or CoCrAlY is performed by a thermal spraying method (hereinafter, referred to as VPS).

[0003]

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. The present invention aims to provide a surface treatment method for imparting high-temperature corrosion resistance to a high-temperature-used metal material in accordance with the above-mentioned technical level and the above-mentioned demand.

[0004]

SUMMARY OF THE INVENTION The present invention provides (1) a first step of coating Pt or Ta, which hardly diffuses heat to a metal material substrate used at a high temperature, and a step of coating pure Cr or Cr on the coating layer in the first step. M 'containing 50 wt% or more
A second step of coating a Cr alloy (where M 'is Ni and / or Co), and an MCrAlY alloy (where M is Ni, Co and F) on the coating layer of the second step.
e) coating the high-temperature-use metal material substrate having each coating layer after the third step with a vacuum furnace or Ar-H _2.
A high-temperature corrosion-resistant surface treatment method for forming a coating layer having excellent adhesion, uniformity, and high-temperature corrosion resistance on the surface of a high-temperature-used metal material substrate, which comprises a fourth step of performing thermal diffusion treatment in an atmosphere furnace. 2) The high-temperature corrosion-resistant surface treatment method according to the above (1), wherein the second step and the third step are repeated a plurality of times according to a request for the thickness of the coating layer.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The first aspect of the present invention is to coat Pt or Ta to a thickness of 2 to 5 μm on a high-temperature metal material base material such as an Fe-based alloy, a Co-based alloy, or a Ni-based alloy by vapor deposition. (1st step), Pure Cr or M'Cr alloy containing 50 wt% or more of Cr (where M 'is Ni and / or Co) is 1 on the coating layer of the first step.
0 to 50 μm thickness (10 to 20 μm for plating and evaporation,
( 2nd step), and MCrAlY is applied on the coating layer of the second step.
An alloy (where M is at least one member from the group consisting of Ni, Co and Fe) is formed to a thickness of 30 to 100 μm (30 to 100 μm by vapor deposition).
50 μm, 50 to 100 μm for thermal spraying) (third step), and the high-temperature-use metal material base having each coating layer after the third step is subjected to a vacuum furnace (vacuum conditions:
0.1～1.0MmHg) or in Ar-H ₂ atmosphere furnace (Ar-H ₂ atmosphere _{conditions: Ar: H 2 = 5:} 1, pressure:
Thermal diffusion treatment (for example, 105 to 100 mmHg)
(0 ° C. × 4 hours or 1150 ° C. × 2 hours) (fourth step) to obtain adhesion to the surface of the metal material substrate used at high temperature,
This is a method for forming a coating layer having excellent uniformity and high-temperature corrosion resistance.

A second aspect of the present invention is the first first aspect of the present invention.
After applying the Pt or Ta coating of the process,
M ′ containing 50 wt% or more of pure Cr or Cr of the second step
The coating of the Cr alloy layer and the coating of the MCrAlY alloy layer in the third step are repeatedly performed until a desired thickness is obtained, and then the thermal diffusion treatment in the fourth step is performed.

(Action) Cr or M 'in the coating layer formed in the second step by the thermal diffusion treatment in the fourth step.
Cr in the Cr alloy layer is MCrAl formed in the third step.
It diffuses into the Y layer, increases the Cr concentration in the MCrAlY layer, and improves the high-temperature corrosion resistance of the MCrAlY layer. Due to the use in high temperature corrosive environment, Cr
Is often consumed and a dechromized layer is formed to deteriorate the corrosion resistance in many cases. However, in the present invention, Cr, M'Cr
Since Cr is supplied from the alloy layer to the MCrAlY layer by diffusion, the formation of a dechromized layer can be suppressed.

Further, since Pt or Ta present at the boundary between the metal material base material used at a high temperature and the coating layer has relatively low self and mutual diffusion coefficients, Cr diffuses into the base material side,
It is possible to prevent the mechanical strength of the substrate from being reduced.

[0009]

EXAMPLES Hereinafter, specific examples of the present invention will be described to clarify the effects of the present invention.

(Example 1) Fe-based alloy A286 shown in Table 1
Co-based alloy ECY768, Ni-based alloy IN738LC
As shown in FIG. 1A, a Pt layer 2 was plated with a target of 2 to 3 μm as a base material 1. Pt plating: chloroplatinic acid: 26 g / liter, sodium nitrite: 10 g / liter, sodium nitrate: 100 g / liter, aqueous ammonia:
90-95 ° C, about 7A in 50g / liter plating bath
/ Dm ² .

[0011]

[Table 1]

Next, Cr plating 3 was performed for a thickness of 10 to 15 μm. Cr plating is chromic anhydride: 250g
/ Liter, chromium sulfate: 3 g / liter, chromium carbonate: 7 g / liter, in a plating bath at 40 to 50 ° C.
The test was performed under the conditions of 10 A / dm ² ( ^{2 to 4} V).

Thereafter, Co-32 wt% Ni-21 wt% Cr-8w is formed by a low-pressure plasma spraying method shown in Table 1 below.
An alloy 4 of t% Al-0.5wt% Y (remainder: Co, the same applies hereinafter) was coated with a target of a thickness of 50 μm.

[0014]

[Table 2]

Furthermore, the same Cr plating treatment and Co
After the low-pressure plasma spraying of the NiCrAlY alloy is performed again, a vacuum furnace (vacuum condition: 0.1 to 1.0 mmH
g) was subjected to a thermal diffusion treatment at 1050 ° C. × 4 hours in FIG.
A high-temperature-use metal material having a coating layer as shown in (b) was obtained. As a result, the high-temperature corrosion resistance of the high-temperature-use metal material having the obtained coating layer is summarized in Table 3 below.

(Example 2) Same Co-based alloy ECY76 as in Example 1
2 was used as a base material 1 as shown in FIG. 2 (a), a Ta metal 5 was coated by a vapor deposition method with a target of 2 mm, and subsequently, a 20 wt% Ni-80 wt% Cr alloy 6 was coated with 10 μm.
m, then Co-25wt% Cr-14wt% Al-1w
t% Y (Co: balance) alloy 7 was coated at 30 μm. The thermal spraying method uses a bipolar sputtering device, voltage,
Current density conditions (DC: 3 to 7 KV, 0.5 to 1.0 mA
/ Dm ² , RF: 5-10 KW, 1-10 W / c
m ² ) under atmospheric conditions (argon gas: 10 ⁻³ atm).

The same Ni-Cr alloy 6 and CoCrA as described above
After the deposition of the 1Y alloy 7 was further repeated twice, a heat diffusion treatment was performed at 1150 ° C. for 2 hours in the same vacuum furnace as in Example 1 to obtain a coating layer as shown in FIG. A metal material used at high temperature was obtained. As a result, the high-temperature corrosion resistance of the high-temperature-use metal material having the obtained coating layer is summarized in Table 3 below.

Example 3 Same Ni-based alloy IN738 as in Example 1
As shown in FIG. 3 (a), the LC was used as the base material 1, the Pt plating layer 2 was plated under the same conditions as in Example 1 with a target of 3 μm, and under the same low pressure plasma spraying conditions as in Example 1, 50 wt% Ni-5 was used.
30 wt.% Of 0 wt% Cr alloy 8, followed by Co-32 wt.
% Ni-21 wt% Cr-8 wt% Al-0.5 wt%
Y alloy 9 is coated, and the same NiCr alloy 8, Co
The NiCrAlY alloy 9 is again low-pressure plasma sprayed by the same thickness, and then an Ar-H ₂ atmosphere furnace (Ar: H ₂ =
5: 1, pressure: 50 to 100 mmHg) at 1050 ° C x
By performing a heat diffusion treatment for 4 hours, a metal material used at high temperature having a coating layer as shown in FIG. 3B was obtained. As a result, the high-temperature corrosion resistance of the high-temperature-use metal material having the obtained coating layer is summarized in Table 3 below.

Example 4 Same Co-based alloy ECY76 as in Example 1
8 was used as the base material 1 as shown in FIG. 4A, and after plating the Pt plating layer 2 at 3 μm under the same conditions as in Example 1, 25 wt% Ni-75 wt under the same low pressure plasma spraying conditions as in Example 1.
% Cr alloy 10 at 50 μm, followed by Co-25 wt% C
r-14 wt% Al-1 wt% Y alloy 7 is coated with a target of 100 μm, and then an Ar-H ₂ atmosphere furnace (Ar: H ₂ = 5: 1, pressure: 50-100 mmHg)
4 at 1150 ° C. for 2 hours.
A high-temperature-use metal material having a coating layer as shown in (b) was obtained. As a result, the high-temperature corrosion resistance of the obtained high-temperature-use metal material having the coating layer is shown in Table 3 below.

Table 3 shows Co-based alloy ECY768.
The Co-25w was formed by the low pressure plasma spraying method shown in Table 1.
t% Cr-14wt% Al-1wt% Y or Co-3
2wt% Ni-21wt% Cr-8wt% Al-0.5
The high-temperature corrosion resistance of the high-temperature-use metal material coated with the wt% Y alloy is also shown as a comparative example.

[0021]

[Table 3]

As a result, the corrosion loss of the high-temperature-use metal material having the coating layers of Examples 1 to 4 according to the present invention was about 60% of that of the comparative material coated with CoCrAlY.
Hereinafter, those coated with CoNiCrAlY # 5
0% or less, and 50% or less of both comparative materials even when compared at the maximum erosion depth.

[0023]

According to the surface treatment method of the present invention, it is possible to obtain a high-temperature-use metal material which is more excellent in high-temperature corrosion resistance than conventional high-temperature-use metal materials.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a method according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view of a method according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating a method according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram illustrating a method according to a fourth embodiment of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ikumasa Ogi 2-1-1, Shinhama, Arai-machi, Takasago-shi, Hyogo Mitsubishi Heavy Industries, Ltd. Inside Takasago Research Laboratory (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 28/00 C23C 4/00 C23C 10/14

Claims (2)

(57) [Claims] A first step of coating Pt or Ta which is hardly thermally diffused to a metal material substrate used at a high temperature;
Pure Cr or Cr on the coating layer of the first step
A second step of coating an M′Cr alloy (where M ′ is Ni and / or Co) containing 50 wt% or more, and an MCrAlY alloy (where M is Ni, Co and Fe) on the coating layer of the second step A third step of coating one or more of the groups), a third step of thermally diffusing the high-temperature-use metal material base having each coating layer after the third step in a vacuum furnace or an Ar-H ₂ atmosphere furnace. A high-temperature corrosion-resistant surface treatment method for forming a coating layer having excellent adhesion, uniformity, and high-temperature corrosion resistance on the surface of a metal substrate used at high temperature, comprising four steps. 2. The high-temperature corrosion-resistant surface treatment method according to claim 1, wherein the second step and the third step are repeated a plurality of times in response to a request for the thickness of the coating layer.