JPS62109960A - Plasma spray-coated heat resistant member - Google Patents

Abstract

PURPOSE:To prevent the exfoliation of a ceramic coating layer from a heat resistant alloy material in the stage of coating the ceramic layer on the surface of the heat resistant alloy material to protect the heat resistant alloy material against a high temp. by subjecting the ceramics prepd. by using partially stabilized ZrO2 as matrix and incorporating fine incompletely molten particles of MgO, etc. therein to plasma spraying. CONSTITUTION:The heat resistant coating layer consisting of the ceramics is formed by plasma spraying on the surface of the heat resistant alloy member of a gas turbine, etc. in order to protect said heat resistant alloy member against the high temp. and to extend the service life thereof. The partially stabilized ZrO2 is used as the ceramics to be used and the mixture composed of 1 or >=2 kinds of powders of MgO, CaO, Cr2O3 and CeO having the coefft. of thermal expansion approximate to the coefft. of thermal expansion of the metallic member of the heat resistant alloy member is incorporated and dispersed in the form of the incompletely molten particles therein. The thermal stress between the ceramic layer and the heat resistant alloy member is relieved and the generation of a crack in the ceramic layer and the exfoliation thereof are obviated. The service life of the above-mentioned member is thus considerably extended.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a technology for improving high-temperature durability of heat-resistant parts, and in particular to plasma radiation I! 2i-E relates to heat-resistant coating technology.

[Technical background of the invention and its problems]

The high-temperature properties required for heat-resistant alloy parts are becoming more severe year by year. In particular, heat-resistant alloy parts used as gas turbine members are now being required to withstand gas temperatures of 1400° C. or more as gas turbines become hotter. However, it is difficult for conventional heat-resistant alloys to withstand such high temperatures.
Ceramic materials such as 8i, N4, and SiC are being considered for turbine components, but it will still take time to put them into practical use.

Therefore, a method has been adopted in which the heat-resistant alloy is used as a high-temperature member while being cooled, but the problem is that the thermal efficiency decreases due to cooling. Nowadays, emphasis is being placed on heat damage resistance that takes advantage of the low thermal conductivity of ceramics.

Heat-resistant coating is a method of coating a conventional low-temperature alloy with a ceramic having low thermal conductivity to protect the base alloy from high temperatures. This heat-resistant coating preferably has excellent heat-insulating properties, appropriate heat-resistant plastering properties, and is also lightweight. In order to fill these grooves to some extent, there is a method of making ceramics resistant to heat damage by plasma spraying. Plasma spraying has good millet production properties and requires little attention to the materials used.
This is a technology for sound.

In order to expand the range of applications of ceramic heat-resistant coatings by plasma spraying, it is necessary to achieve long life and reliability in higher temperature regions.

When a ceramic coating is formed on a metal substrate, fatigue and deterioration of the coating layer due to a difference in coefficient of thermal expansion, or a decrease in adhesive strength and the resulting peeling of the coating layer are serious problems.

Conventionally, after selecting a metal base material and a ceramic coating layer with a small difference in coefficient of thermal expansion, a method of forming a layer with an intermediate coefficient of thermal expansion between the coating layer and the base material was considered. However, it is still insufficient as a method for alleviating thermal stress.

[Purpose of the invention]

The present invention alleviates the thermal stress caused by the difference in thermal expansion coefficient between the gold 24 base material and the ceramic heat-resistant coating layer, and also changes the stress distribution state within the ceramic heat-resistant coating layer. This is intended to increase the longevity and reliability of the coating layer.

[Summary of the invention]

The present invention mixes incompletely molten powder in the ceramic coating layer formed by plasma spraying to change the thermal expansion coefficient of the ceramic 1 over the entire layer or locally, and to increase the internal heat By changing the stress distribution, the thermal stress between the ceramic yuzu layer and the four base gold layers is alleviated. In the conventional method, the coefficient of thermal expansion changes rapidly between the gold 4 base material and the ceramic coating layer, and thermal stress during flow thermal cooling is concentrated at the interface. According to the present invention, by dispersing the incompletely fused powder whose coefficient of thermal expansion is close to that of metal, it is possible to alleviate the stress between the 1-metal metal 4 base material and the ceramic coating layer.

Currently, partially stabilized zirconium oxide is the most preferred material for ceramic heat-resistant coating layers due to thermal properties such as mechanical properties and coefficient of thermal expansion. Also.

As the incompletely dissolved particles, particles having a large coefficient of thermal expansion and close to that of the metal base material may be used. For example, MIlo.

Cr, 01, CaO, etc. have a large coefficient of thermal expansion and are suitable.

In order to form such a sprayed layer by plasma spraying, powder may be mixed in between the test piece and the spray gun while spraying. The temperature of the thermal spraying arc during thermal spraying decreases as it moves away from the gun. If the powder is introduced from a part close to the gun, there is a high possibility that the powder will melt in the bath and form a solid solution with each other, making it difficult to form two phases. If the powder is introduced near the object to be sprayed, it remains in an undissolved or incompletely dissolved state.

It can be engulfed in the thermally sprayed continuous particles to form five two-layered particles.

A possible method for introducing undissolved particles is to use a gas flow.

The particle size of the mixed particles is most preferably 50 μm or less since the thickness of the entire sprayed layer is about several hundred microns.

〔Effect of the invention〕

As detailed above, due to the uninvention, the thermal stress between the ceramic heat-resistant coating layer and the metal base material, which was a major problem in the United States, has been alleviated, resulting in a significant extension of life and cost reduction. .

[Voices from implementing the invention]

Two sheets of Ni-based alloy (IN931) measuring 50 mm x 50 mm x 2 tons were prepared. After sandblasting both sides of the plate with alumina powder with a particle size of 1 mm, each of the two plates was first plasma sprayed with about 100 μm of Ni-200r alloy. The sprayed layer is a metal bonding layer, and its coefficient of thermal expansion is smaller than that of the base material.

组(ko8 ut % Y, O, stable (= Z r O,
A coating layer having an average thickness of about 200 μm was formed by Hg irradiation.

Similar to ■■, the Ni-20Cr gold corner bonding layer is 100 μm thick.
Sprayed. Next, while supplying MgO powder of 50 μm to 10 μm with argon gas from a distance of 10 mm from the test piece and about IQ mm above the test piece, Y-stabilized Zr 9 powder was plasma sprayed to form a 200 mm spray nozzle. did. Meanwhile, the amount of M.90 powder fed was reduced so that the top 100 μml contained almost no MgO. The two types of test pieces obtained were heated at 1100°C for 10
A thermal fatigue test of heating for 1 minute and cooling at room temperature for 10 minutes was conducted, and the occurrence of cracks in the coating layer was observed with the naked eye. The results are shown in Table 1 as the number of thermal cycles until cracking occurs.

Table 1 This thermal fatigue test is used to evaluate and evaluate the thermal impact vehicle properties, the heat insulation properties as a heat-resistant coating, and the oxidation properties of the base material.

Agent Patent Attorney Norihiro Kon Same Bamboo Flower Kikuo

Claims (5)

[Claims] (1) A plasma spray coated heat-resistant member characterized in that a coating layer in which incomplete or unmelted particles are mixed and dispersed in a melted solidified structure is formed by plasma spraying. (2) The plasma spray coated heat-resistant member according to claim 1, wherein the thermal expansion coefficient of the incompletely fused particles to be mixed is larger than that of the ceramic of the coating layer matrix. (3) ZrO_2 partially stabilized coating layer matrix component
A plasma spray coated heat resistant member according to claim 2. (4) Mixed incompletely melted particles are mixed with MgO, CaO, Cr_
The plasma spray coated heat-resistant member according to claim 3, characterized in that the plasma spray coated heat-resistant member is a single particle or a mixed particle selected from 2O_3 and CeO. (5) The plasma spray coated heat-resistant member according to Claims 1 and 4, wherein the mixed incompletely fused particles have a particle size of 50 μm or less.