JPH1180920A - Material for high temperature corrosion resistant combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a material for a combustion device having high temp. corrosion resistance and oxidation resistance by thermally spraying a thermal spraying material having a specified compsn. on an Ni base alloy as a base metal. SOLUTION: As the Ni base alloy as a base metal, 45Cr-30Ni-Fe, 50Cr-50Ni, McAlloy, inconel 625 or the like are used. As the thermal spraying material, the one obtd. by mixing CoNiCrAlY (e.g. by weight, 30 to 50% Co-25 to 35% Ni-15 to 25% Cr-3 to 10% Al-0.3 to 0.7% Y) with Cr2 C2 ) good in corrosion resistance so as to be regulated to 20 to 90% is used. Furthermore, the Ni base alloy as the base metal is subjected to calorizing treatment to obtain a material for a high temp. corrosion-resistant combustion device. The calorizing treatment is the one in which Al is subjected to pack cementation to the surface of the base metal to increase the concn. of Al effective for the corrosion resistance only of the surface of the base metal, and is generally executed in such a manner that the base metal is buried in Al2 O3 -NH4 Al powder including Al, and heating treatment is executed in a reducing gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion device material having corrosion resistance and oxidation resistance at high temperatures.

[0002]

2. Description of the Related Art Conventional combustion devices such as boilers, for example, burner nozzles, air nozzles and diffusers are exposed to the highest temperature in a boiler, and corrosion becomes a problem.
A material containing a large amount of Cr acting as an effective element for corrosion, such as ONi and 50Cr-50Ni, or a material having even better corrosion resistance (for example, CoNiCrAl).
Y, ceramics, etc.) coated on the surface of the above material have been used. However, recent boiler by temperature rise due to increase in the low NO _x operation and thermal load, became insufficient corrosion resistance in the conventional materials.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned state of the art, and has as its object to provide a material for a combustion apparatus such as a boiler having a longer corrosion life than a conventional material for a high-temperature corrosion-resistant combustion apparatus.

[0004]

The present invention provides the following constitution (1):
To (3). (1) A material for a high-temperature corrosion-resistant combustion apparatus, characterized by spraying a Ni-based alloy as a base material with a sprayed material in which Cr ₃ C ₂ is mixed with CoNiCrAlY alloy in an amount of ₂₀ to 90 wt%. (Hereinafter, this is referred to as a first invention material). (2) A material for a high-temperature corrosion-resistant combustion device, which is obtained by subjecting a Ni-base alloy as a base material to a calorizing treatment (hereinafter, referred to as a second invention material). (3) A Ni-based alloy as a base material is sprayed with a thermal spray material in which Cr ₃ C ₂ is mixed with CoNiCrAlY alloy in an amount of ₂₀ to 90 wt%, and then subjected to a calorizing treatment. A material for a high-temperature corrosion-resistant combustion device (hereinafter, referred to as a third invention material).

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first invention material will be described. 45Cr-30N as Ni-base alloy as base material
i-Fe, 50Cr-50Ni, Mc Alloy, Inconel 625 and the like are used. Co as spray material
NiCrAlY (for example, 30 to 50% Co by weight%)
-25 to 35% Ni-15 to 25% Cr-3 to 10% A
1-0.3 to 0.7% Y) is used as a thermal spray material containing a large amount of Cr ₃ C ₂ having good corrosion resistance. A highly corrosion-resistant coating is formed by adding Cr ₃ C ₂ to CoNiCrAlY which has been conventionally used as a thermal spray material. C
The ratio of r ₃ C ₂ to CoNiCrAlY is 20 to 90% by weight of Cr ₃ C ₂ .

The reasons for limiting the components of the thermal spray material will be described below. Since Cr ₃ C ₂ itself contains a large amount of Cr,
Increasing this ratio is effective in terms of corrosion resistance. However, when a large amount of Cr ₃ C ₂ is contained during thermal spraying, CoNiCrAl
Since the wettability between Y and Cr ₃ C ₂ is poor and the sprayed film contains many pores, the maximum value of Cr ₃ C ₂ is 90 wt.
%. In addition, Cr ₃ C ₂ is 90 from the viewpoint of film adhesion.
wt% or less. The minimum value is set to 20 wt% in order to secure corrosion resistance.

Next, the second invention material will be described. Since the Ni-base alloy serving as the base material is the same as the first invention material, the description is omitted. The calorizing treatment is a treatment in which Al is diffused and penetrated into the surface of the base material to increase the Al concentration effective for corrosion resistance only on the surface of the base material. Generally, Al ₂ O ₃ −
This is performed by embedding a base material in NH ₄ Al powder and performing heat treatment in a reducing gas.

[0008] Further, the third invention material will be described. The Ni-base alloy of the base material is the same as that of the first invention material, and the description is omitted. Further, the composition of the mixed thermal spraying material of CoNiCrAlY alloy and Cr ₃ C ₂ is the same as in the case of the first invention material, and the calorizing treatment is the same as in the case of the second invention material.

[0009]

EXAMPLES Hereinafter, specific examples of the material for a high-temperature corrosion-resistant combustion device of the present invention will be described to clarify the effects of the present invention.

(Example 1) Hereinafter, a specific example of the material 1 of the present invention will be described. Table 1 shows the chemical components of the thermal sprayed material and the base material used in the test. A 45Cr-30Ni-Fe alloy was used as a base material sprayed with the spray material. Comparative materials 1, 2, and 3 use a thermal spray material outside the composition range of the present invention, and comparative materials IV and V represent the base material itself. Since CoNiCrAlY cannot be sprayed unless it is powder, plasma spraying was used as the spraying material. The sprayed film thickness is preferably at least about 200 μm from the viewpoint of corrosion life. When the film thickness is increased, separation occurs due to a difference in thermal expansion between the base material and the sprayed film.
About 500 μm is desirable. Here, the sprayed film thickness is 400
μm and tested.

[0011]

[Table 1]

FIG. 1 shows the results of corrosion tests of the first invention materials I to III and the comparative materials I to V shown in Table 1. The corrosion test conditions simulated the environment of the boiler combustion equipment members, and the adhesion ash composition was 2
0 mol% V ₂ O ₅ -80 mol% Na ₂ SO ₄ , the gas contains H ₂ S having a strong corrosive action, that is, 2000
ppmH ₂ S-2% O ₂ -15% CO-10% H ₂ -N
₂ bal was used. The test was performed at a temperature of 800 ° C.
800 ° C to 11
Although the temperature is about 00 ° C., the corrosion resistance of the material does not change even if the temperature fluctuates. Therefore, the test temperature was 800 ° C.
The test method was a 14 × 14 × 3 mm test piece (45Cr-3
0Ni-Fe) was sprayed and the amount of ash was 20 m
The ash having the above composition was applied to the surface of the sample so as to obtain g / cm ^2, and the sample was kept in a corrosive gas having the above composition for 100 hours. In the evaluation of the test, the scale thickness was measured from the cross section after the test, and thereby the corrosion resistance was evaluated. As is clear from the test results, the developed material has better corrosion resistance than the conventional material and can extend the corrosion life.

Further, apart from the corrosion resistance, as a characteristic of the sprayed film material, there is a problem of adhesion to the base material. Therefore, a thermal cycle test was performed to confirm this. The test method is similar to that of the corrosion test.
Hold at this temperature for 0 minutes. Thereafter, the test piece was taken out of the furnace and forced air-cooled with a fan. The test has 10
This was repeated twice, and then the presence or absence of peeling of the sprayed film was confirmed by cross-sectional inspection. Table 2 shows the results. From this result, it was clarified that the material of the present invention has an adhesiveness equal to or higher than that of CoNiCrAlY.

[0014]

[Table 2]

As described above, the first invention material has the same or higher adhesiveness as the conventional material and has improved corrosion resistance, so that it can be used as a thermal spray material for boiler combustion equipment members and the corrosion life is improved. Therefore, a highly reliable boiler combustion device can be provided.

(Embodiment 2) In the calorizing treatment, it is preferable that the adhesion with the base material is secured and the calorizing treatment is formed thick. Then, in order to make such a treatment layer, calorificization was performed under various treatment conditions, and the adhesion between the treatment layer and the base material was evaluated by the same heat cycle test as in Example 1. As a calorizing method, 45Cr-30Ni-Fe is used as a base material,
This was carried out by a powder method of embedding in Al ₂ O ₃ —NH ₄ Cl powder containing Al and treating in a reducing gas (H ₂ gas). The processing conditions were such that the time was 10 hours (fixed) and the processing temperature was changed. The processing temperature is 1100 ° C, 100
Six conditions of 0 ° C, 900 ° C, 800 ° C, 700 ° C, and 600 ° C were set. Table 3 shows the results. The thickness of the calorized layer is also shown.

[0017]

[Table 3]

From this result, at 1100 ° C., peeling occurred because the film was too thick. At 600 ° C., it was difficult to form the film itself. From this result, the thickness of the calorie layer is 100
６００600 μm is desirable. Also, to make the thickness above,
The processing conditions are 700 ° C. × 10 hours to 1000 ° C. × 1
0 hr is appropriate. In addition, 45 was used as the base material for the test.
Although Cr-30Ni-Fe was used, if the other constituent elements of the Ni-based alloy consisted of Cr and Fe, the processing conditions were hardly changed, so that other Ni-based alloys (other constituent elements were Cr and Fe) were used. This condition can also be applied to Fe).

FIG. 2 shows the results of the corrosion test. The test conditions are the same as in Example 1. From these results, the material of the present invention had better corrosion resistance than the conventional material (45Cr-30Ni-Fe). By performing the calorizing treatment on the Ni-based alloy as described above, it is possible to provide a highly reliable boiler combustion device having a longer corrosion life than before.

(Embodiment 3) The surface of the thermally sprayed embodiment 1 is subjected to the calorizing treatment of the embodiment 2 so that the embodiment 1
Since the fine pores of the sprayed coating can be filled, corrosive ash and gas intrusion through the pores can be suppressed, and the corrosion resistance is further improved. Therefore, a corrosion test and a heat cycle test were performed under the same test conditions as in Example 1 and Example 2 using the test piece manufactured by this method. Here, as described in Example 1, the composition of the sprayed material was such that the content of Cr ₃ C ₂ was 20 to 90% and the sprayed film thickness was 200 to 1500 μm. The thickness of the calorized layer is preferably about 600 μm as a maximum value in consideration of the peeling of the film from the experience of Example 2, and about 10 μm as a minimum value in consideration of corrosion resistance.

Table 4 shows the results of the heat cycle test, and FIG. 3 shows the results of the corrosion test. Note that the test conditions are the same as those in Example 1 and Example 2. As a result, the penetration of the corrosive substance into the film was suppressed more than in the sprayed film of Example 1, so that the corrosion resistance was improved. The comparative material 1 and the comparative material III have good corrosion resistance and peelability, but the effect of the calorizing treatment cannot be sufficiently exerted (the same as that of the untreated material). Therefore, at least 100 μm is required for the calorizing treatment. As described in the first embodiment, there is no problem if the base material used is a Ni-based alloy (other components are Cr and Fe).

[0022]

[Table 4]

As described above, by performing the calorizing treatment on the sprayed film of the first embodiment, it is possible to provide a highly reliable combustion apparatus with improved corrosion resistance.

[0024]

According to the present invention, a material for a high-temperature corrosion-resistant combustion device can be provided, and its industrial effect is remarkable.

[Brief description of the drawings]

FIG. 1 is a chart showing the results of a corrosion test of one example of the first invention material (including a comparative material).

FIG. 2 is a table showing the results of a corrosion test of one example of the second invention material (including a comparative material).

FIG. 3 is a table showing the results of a corrosion test of an example of the third invention material (including a comparative material).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ichiji Yamada 1-1, Akunoura-cho, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard (72) Inventor Takayuki Sudo 1-1-1, Akunoura-cho, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd., Nagasaki Shipyard

Claims (3)

[Claims] 1. A Ni-based alloy as a base material is made of CoNiCr.
A material for a high-temperature corrosion-resistant combustion device, which is obtained by spraying a spray material mixed with an AlY alloy so that Cr ₃ C ₂ becomes ₂₀ to 90 wt%. 2. A material for a high-temperature corrosion-resistant combustion apparatus, wherein a Ni-base alloy as a base material is subjected to a calorizing treatment. 3. The Ni-base alloy as a base material is made of CoNiCr.
A material for a high-temperature corrosion-resistant combustion device, which is obtained by spraying a spray material mixed with AlY alloy so that Cr ₃ C ₂ becomes ₂₀ to 90 wt% and then performing a calorizing treatment.