JPS61106763A - Thermal spraying alloy powder - Google Patents

Abstract

PURPOSE:To obtain a thermal spraying alloy powder for forming a covering which has extending over many hours excellent oxidation resistance and corrosion resistance characteristics at a high temperature by specifying a composition consisting of Cr, Al, Y, Zr, Hf, a rare earth element, Ni, Co and Fe, etc. CONSTITUTION:A thermal spraying covering which is excellent in its high temperature corrosion resistance and high temperature oxidation resistance characteristics, and also excellent its thermal fatigue characteristic and ductility in a high temperature is formed by a thermal spraying alloy powder consisting of 30-45wt% Cr, 6-14% Al, 0.05-2% at least one kind of Y, Zr, Hf, a rare earth element, and their mixture, and at least one kind of Ni, Co and Fe as a balance. The thermal spraying alloy powder is used for thermal spraying in a low pressure inert gas atmosphere of 25-350 TORR especially, a covering layer which is dense and has an excellent characteristic is formed, and by setting its particle diameter to <=10-74mum, the workability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thermal spray alloy powder (2) suitable for internal combustion engines such as gas turbines (2), for forming a coating having excellent anti-burr and anti-corrosion properties at high temperatures. related.

[Technical background of the invention and its problems]

Heat engines and chemical equipment tend to operate for long periods of time in an atmosphere with strong chemical reactions and at higher temperatures in order to increase their efficiency.

For example, in order to improve the efficiency of a gas turbine, it is necessary to increase the temperature of the combustion gas.

This gas temperature is often limited mainly by the materials of the gas turbine components. In addition, for economical operation (2) in gas turbines, it is desirable to use low-cost, i.e., low-grade fuels.Low-grade fuels include V, Na, 8
The content of these materials is large, and there are significant restrictions on the selection of materials from the viewpoint of high temperature corrosion resistance.

Conventionally, superalloys such as those used in gas turbine components are coated on six sides to improve high-temperature corrosion resistance including high-temperature oxidation resistance. Coating with an alloy having a high Cr content is effective against such high-temperature corrosion (2).Therefore, coating materials having the following composition are listed as having excellent high-temperature corrosion resistance.

Cr: 35-45 weight M% A-e28-101 co20-20I When using such a high Cr coating material, the following points need to be taken into consideration. C: Due to the large content, the coating layer tends to have low ductility and poor mechanical strength.U has local corrosion resistance (there are two problems, AA and O).

The amount of solder required for film formation is kept at a low temperature (°C).Therefore, there is a risk of depletion of fx5k13 due to diffusion during high-temperature use.In particular, when coating the next surface by thermal spraying, the AA may become thicker during general spraying. Excess (secondary) may accelerate the depletion of heat. Deficiency of heat reduces heat oxidation resistance.

1) By the way, the effectiveness of the corrosion-resistant coating on gas turbine components and the like is enhanced by making it a thick film of nearly 100 μm. Such a thick coating layer is made of PV
It is difficult to obtain a sufficient thickness using vapor deposition methods such as D or CVD, and even if it is possible, the coating layer often lacks ductility and is brittle.

Therefore, for forming a coating layer with a high Cr content, thermal spraying that has a high film thickness formation rate is appropriate, and low-pressure thermal spraying that produces a dense coating layer is more effective.

Therefore, there has been a desire for a thermal sprayed alloy powder that provides a narrow surface coating layer that can maintain a low Cr content and a low concentration.

[Purpose of the invention]

This invention improves the above-mentioned problems, and provides excellent high-temperature corrosion resistance and high-temperature oxidation resistance for a long period of time (even when used in internal combustion engine parts that use low-grade fuel containing impurities such as V). It is an object of the present invention to provide a thermal spray alloy powder for obtaining a coating having the following properties by thermal spraying.

[Summary of the invention]

This invention provides a thermal spray coating with excellent high-temperature corrosion resistance.6.
Thermal spraying compound 1 powder 1a6・next ":8" composition is shown.
Cr
: 80-45 weight% A! = 6-14 l At least one selected from a mixture of Y, Hf, Zr and rare earth elements: 0.05-2% by weight Balance: N
l, at least one of CGI Fe. This thermal sprayed alloy powder is a high-Or superalloy, and although it is easily weakened, it has a property of having a low coefficient of thermal expansion by precipitating an α phase in a matrix of a γ phase, It also has the advantage of improving thermal fatigue properties and high-temperature corrosion resistance as a surface coating phase, and also improves ductility at high temperatures.

Next (2) The limitation of the composition range of the thermal spray alloy powder related to this invention will be described.

(1) Cr: 80% to 45% As the content of Cr-containing magnesium increases, the high-temperature corrosion resistance increases significantly. However, when the thickness exceeds 45 cm, the precipitation of α phase is intense.
Tends to have poor strength. In addition, when the content is 80% or more, precipitation strengthening of fine α phase can be obtained depending on the amount added, and at the same time (-excellent high-temperature corrosion resistance C2).

(2) A! By adding 26 to 14 inches, a coating layer (bistable film) is formed, resulting in extremely high temperature oxidation resistance. It suppresses α depletion, exhibits excellent high-temperature oxidation resistance, and enables fine precipitation of α phase at the same time (at a diCr content of 30 to 45%. Also, when the content exceeds 14%, β phase precipitation occurs). This causes a significant decrease in ductility and construction problems.

(3) At least one selected from Y, Hf, Zr, rare earth elements, and mixtures thereof: 0.05 to 2
% Addition of these elements has the effect of reducing the oxidation rate of the coating layer and suppressing peeling of the protective oxide film. It is appropriate that the amount of these additives slightly exceeds the solid solubility limit of each of them, and if the amount exceeds too much, the ductility will decrease. In addition, in practice, Y
It is preferable to set Hf to 0.8 to 2 inches.

(4) Remainder: Ni, Co, Fe These elements form the matrix of the alloy. Among these, Nl is ductile (;
It can be said to be a particularly effective residual element in the present invention, since M is excellent and depletion of M is small during long-term use at high temperatures.

The above-mentioned thermal spray alloy powder can be thermally sprayed onto high-temperature parts etc. to a thickness of 100μ.
By forming a thick film coating with a humidity of 1.5 m, the high TH1 bird-eating resistance is significantly improved. In particular, thermal spraying from 5TO to 3
When actually measured in a low-pressure inert gas atmosphere of 50 TORR, a thick coating was obtained, and its high temperature resistance properties were extremely excellent, taking full advantage of the composition of the thermal spray alloy powder of the present invention. Furthermore, the area of thermal spray alloy powder is 1
By sizing the particles to 0 μm or more and less than 74 μm, the powder can be fed smoothly during thermal spraying, especially when spraying in a low-pressure atmosphere.A sprayed layer with a dense and uniform structure can be obtained.

〔Effect of the invention〕

The thermal spray alloy powder according to the present invention has the effect of forming a narrow surface coating having extremely excellent high-temperature corrosion resistance even during long-term use at high temperatures, by thermal spraying, particularly by i-spraying in a low-pressure atmosphere.

[Embodiment 1 of the invention] 1. ≦2 so that the ingredient composition is the same as that shown in the first coating.
Ni.

1ゝ・I Co, Fe, Cr, Al1. Y, Hf, Z
R is placed in a mag-screw pot, and M is added as a deoxidizing agent.
n was added to perform dissolution. Afterwards, it was atomized and powdered in an Ar atmosphere.

Next, the particles were divided into two particles with −74 μm+10 μm≦ to obtain a thermal spray alloy powder.

Next, Ni-based superalloy I N 989 was processed into a 20x5 (order 11.2), and its surface was sandblasted with AAtO particles (2) with a grain size of approximately 1 layer.Then, the sized thermal spray powder was subjected to a plasma spraying device Thermal spray distance 100 order by
Current Asahi 800A% hair current approximately 100μm under 86V conditions
The following evaluation test was conducted to confirm the high temperature corrosion resistance of the coated superalloy which was thermally sprayed to the desired thickness.

2 types of synthetic corrosive ash (A) 20wt To '1105
・8Q wt * NatSO4゜mon) 80 wt
Sorrow v, 0.・Mix 20vrt with a reagent and coat the second side of the superalloy! ':,, 20mf101 were applied uniformly. Next, after being kept in an electric furnace at 900 C for 8 hours, it was rapidly cooled in the atmosphere. Later, (NaOH18wt
% + KMnO48wt%) in an aqueous solution for 1 hour and 1
01 quench was descaled by boiling it in an ammonium aqueous solution for 1 hour. After repeating this synthetic ash corrosion test and descaling eight times, the cross-sectional structure of each coated superalloy was observed and the damage thickness of the superalloy coating and coating layer due to corrosion (= corrosion) was measured. Shown below.

Table 1 (wt) (blank below) [Example 2] Example 1 Thermal sprayed alloy powders of No. 2 and 10 in t=7
Coated superalloy specimens were prepared by thermal spraying in the same manner as in Example 1 in an Ar atmosphere at pressures of 0 TORR, 150 TORR, and 400 TORR. Next, real demon example 1
and colleagues' synthetic corrosive ash was applied, kept in an electric furnace at 1100C for 623 hours, and then rapidly cooled in the atmosphere. The damage thickness of the coating layer was measured from descaling temporary section structure observation C2. The results are shown in the 8th thorn.

Claims (4)

[Claims] (1) 30 to 45% by weight Cr, 6 to 14% by weight Al, 0.05 to 2% of at least one selected from Y, Zr, Hf, rare earth elements, and mixtures thereof, and the balance is Ni. , Co, Fe, and a mixture thereof. (2) The thermal spray alloy powder according to claim 1, which is used for thermal spraying in an inert gas atmosphere of 25 to 350 TORR. (3) The thermal spray alloy powder according to claim 1 or 2, which has a particle size of 10 μm or more and less than 74 μm. (4) The thermal spray alloy powder according to claim 1, 2 or 3, wherein the remainder of the thermal spray alloy powder is Ni.