JPH0436454A - Thermal spraying material and thermally sprayed heat resisting member - Google Patents

Abstract

PURPOSE:To improve product yield and to provide prolonged heat resistance and thermal shock resistance by blending 2MgO.SiO2 and MgO.4ZrO2 in a specific ratio. CONSTITUTION:A thermal spraying material is composed of a 2MgO.SiO2- MgO.4ZrO2 oxide and has a composition which consists of, by weight, 20-50% 2MgO.SiO2 and 50-80% MgO.4ZrO2 and in which 2MgO.SiO2+MgO.4ZrO2=100 is satisfied. A heat resisting member is formed by thermally spraying the above coating material on a heat resisting metallic material or parts having metallic coating layer excellent in high temp. corrosion resistance. The grain size of the oxide as coating material is regulated to 5-500mum, and particularly, it is preferable to regulate average grain size to 10-100mum. This thermal spraying material has superior mechanical strength. By using this thermally sprayed layer, a turbine blade, etc., having excellent thermal shield effect and heat resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention relates to a thermal spray coating material that is imparted with heat resistance and has excellent heat insulation properties, which is used as a thermal spray coating for surface improvement of ceramics, metals, etc. Among the technologies for improving high-temperature durability of heat-resistant parts, especially for parts such as cast turbines,
The present invention relates to a heat-resistant member coated with these thermal spray coating materials by an optimal plasma spraying method.

[Prior Art] The high-temperature characteristics required of heat-resistant and thermal shock-resistant members are becoming more severe year by year. Among these, cast turbines exhibit higher efficiency as they are operated at higher temperatures, so there is a constant demand for higher operating temperatures. For this reason, 53C is a material that has both heat resistance and thermal shock resistance.
Fine ceramics such as 513N4 are being considered, but at present gas turbine parts are mainly manufactured from metal materials because of problems with impact strength.

However, use of heat-resistant metal materials such as Ni-based and Co-based materials is limited to temperatures below 1000°C. Therefore, various methods for cooling or thermally shielding gas turbine components have been investigated when they are applied to gas turbine components. Heat shielding is the metal (hereinafter referred to as base material) of high-temperature heat-resistant parts such as gas turbines.
The purpose is to form a ceramic layer on the surface of the material to lower the base material temperature. Ceramic powder, which has low thermal conductivity, high thermal shock resistance, and high emissivity, has been used as a thermal spray coating material for some time.

Examples of materials that have been used so far for such purposes include ZrO2 and the like to which a rare earth oxide such as Y2O3 is added as a stabilizer. However, even with the thermal spray coating obtained using this currently best thermal spray material, the coating layer tends to peel off from the base material and lose its functionality in gas turbines that undergo intense thermal cycles of rapid cooling and rapid heating. It was observed.

Furthermore, since these materials use rare earth oxides, they are expensive when used alone, and the thermal spraying materials produced are also very expensive, making it difficult to use them in large quantities for structural materials for industrial purposes. is quite problematic in terms of cost.

Generally, when thermal spray coated parts are used under intense thermal cycles of rapid heating and cooling, thermal distortion occurs between the base material and the coating, and the coating layer cannot follow the rapid thermal expansion of the base material, causing cracks and peeling of the coating layer. does not exhibit adequate durability. For this reason, various efforts have been made to develop thermal spray materials that not only have low thermal conductivity but also have an expansion coefficient close to that of the base material. In addition, a layer made of a mixture or composite of the metal and ceramic layers, which is the main cause of peeling, was provided (for example, in Japanese Patent Application Laid-Open No. 55-11388
0, etc.), or by forming fine cracks in the ceramic layer by heat treatment at high temperature and for a long time (for example, JP-A-56-54).
905, etc.) or a ceramic layer after forming it, microscopic cracks are formed in the layer (for example, in Japanese Patent Application Laid-Open No. 58-87).
Various proposals have been made, such as parts such as 273 etc.

[Problems to be Solved by the Invention] However, although each of the above-mentioned conventional means has been improved, their effects have been limited due to the results of heat cycle tests and the like. The present invention takes these current circumstances into consideration,
A material for thermal spray coating that is very inexpensive compared to Y2O3ZrO2, etc., has a high product yield, is economical, and has an extended lifespan, has heat resistance and thermal shock resistance, and thermal spray coating heat resistant parts such as cast turbine parts that are coated with this material. is intended to provide.

[Means for Solving the Problems] The inventors have conducted intensive research to find a material that has heat resistance and thermal shock resistance. the result,
Magnesium silicate and Mg0, which also exist as natural resources.
4. It has been found that by combining ZrO2, a completely new thermal spraying material that does not use rare earths and is inexpensive and has excellent heat resistance and thermal shock resistance can be obtained.

That is, the present invention is a 12 MgO-5iO2-lAg0.4 ZrO□-based oxide, the composition of which is 20≦2 MgO.
n2≦50.50≦MgO・4ZrO2≦80, and 2
MgO-5iO□+ MgO・4ZrOZr02=
A material for thermal spray coating, characterized in that it consists of 100.

2. A component made of a heat-resistant metal material, which has a metal coating layer on its surface that is equivalent to or has higher high-temperature corrosion resistance than the heat-resistant metal material, and further has the first metal coating layer on the metal coating layer. A thermal spray coated heat-resistant member characterized by being thermally sprayed with the thermal spray coating material according to item 1.

3. A material for thermal spray coating, characterized in that it is particles of each of the oxide materials, compounds, composites, or mixtures described in item 1 above.

4 The particle size of the oxide material described in item 1 above is 5 to 500μ
A material for thermal spray coating, characterized in that the average particle diameter is adjusted to m, and particularly has an average particle diameter of 10 to 100 μm.

5. A thermal spray coated heat-resistant member, characterized in that the thermal spray coating material described in item 2 above is the thermal spray coating material described in item 3 above.

It is.

The present invention will be specifically explained below.

We attempted to develop a material for thermal spray coating using magnesium silicate as a starting material for ceramic materials that are stable at high temperatures, have a high heat resistance effect, have a relatively large coefficient of thermal expansion, and can be manufactured at low cost. rMgo・SiO for magnesium silicate compounds
2''r 2 MgO.5iO2J and the like are known. However, MgO.5in2 has a relatively high content of 5in2, and its adhesion to the base material is poor due to poor leakage during thermal spraying, and cracks occur when thermal cycles are applied. Based on these results, the magnesium silicate thermal spray material has 2M
gO・SiO□ was selected. In addition, in order to further improve the effects of heat insulation and heat resistance, various studies have shown that MgO・4ZrO
2 was selected, and a plurality of stiff materials were used for the thermal spray coating material of the present invention. The use of a plurality of these heat-resistant and heat-insulating materials exhibits better heat-resistance and heat-insulating properties than conventional heat-insulating materials, and can be expected to form a highly reliable coating layer.

2 MgO-SiO2 can be used as a mixture or composite, but it is effective to use a pure mineral (forsterite). Compounds, composites, and mixtures of MgO.4 and ZrO2 can also be used, but compounds or composites sprayed and granulated with a spray dryer or the like are preferred. The material of the present invention has a particle size adjusted to 5 to 500 μm, particularly preferably an average particle size of 10 to 100 μm.

The reason why the composition range of the present invention is limited as described in 1 is as follows. 2 MgO・SiO2 is 50% by weight
If the amount is more, not only will the coefficient of thermal expansion not be able to follow that of the base material, but as the amount of 5in2 contained increases, the leakage will be poor and peeling will occur.

If MgO.4 ZrO2 is more than 80% by weight, the high temperature stabilization effect will be lowered, which is not preferable. If the particle size of the thermal spraying material of the present invention is 5 μm or less, the powder supplied to the thermal spraying gun will not flow well, making it impossible to form a good coating and reducing the yield during thermal spraying. Furthermore, if the thickness is 500 μm or more, unmelted particles will be formed in the antinode of the sprayed wave, resulting in a decrease in the adhesion of the coating.

The thermal spray material of the present invention is characterized in that two types of materials are combined, composited, or mixed in various proportions. This improves durability. Furthermore, a coating made of this material not only has excellent heat resistance and heat insulation properties, but also exhibits hot expansion behavior similar to that of the base material. This has great industrial significance for this thermal sprayed material, which can suppress damage caused by peeling off of the coating.

Various embodiments of the present invention will be described below.

Peeling of the ceramic layer, which is the main cause of reduced service life, is caused by thermal stress due to the difference in coefficient of expansion between metal and ceramic. To alleviate this, various ceramics with relatively large coefficients of thermal expansion are selected and subjected to thermal shock. A test was conducted. The base material is a 50x 50x 5 inI Ni-based alloy (IN939
After blasting with alumina powder, NlCrAIY alloy, which is a metal with high high temperature corrosion resistance, is first applied by low-pressure plasma spraying to a thickness of 100 μm. A thermal spraying material adjusted to have an average particle size of about 30 μm was plasma sprayed. The obtained test piece was heated at 1200°C for 15 minutes and heated at room temperature for 15 minutes.
It was subjected to a thermal shock test of cooling for minutes, and the number of thermal cycles until cracking was investigated.

The results are shown in Table 1.

From this test result, No. 6-2 MgO-5iO2-5
0wt96Mg0・4Zr (No from J2, 11 of 2
MgO-SiO2-80wt'4 Mg0・4ZrO2
It was found that the material showed a durability of more than $10 thermal shocks and had good thermal shock resistance.

In addition, 2 MgO-5iO2-MgO・4ZrOZrO2
Regarding the raw materials, it was found in this test that composites had the best thermal shock resistance, followed by compounds and mixtures in that order. Figure 1 shows No. 1, which showed good thermal shock resistance.
10/2 MgO-SiO2-70wt! k MgO
- A cross section of a film is shown using 4ZrOZr0z as a representative example. There were many fine vertical cracks in the film, and it is presumed that these vertical cracks improved the thermal shock resistance.

[Example Example 1] Ni (:rAIY) was sprayed under reduced pressure to 0.1 mm on the first and second stage stationary blades of a gas turbine for power generation that uses kerosene, and the present invention was coated with Ni (:rAIY) adjusted to an average particle size of about 30IJI11. Thermal spray coating material, 2 MgO・5iO2-50wt%; M
gO・4 Zr02 (composite raw material), 2 Mg (lSi0
2-70wt96vgo・4 ZrO2 (composite raw material) was sprayed to a thickness of 0.2mm each, and the turbine inlet scum temperature was 11
Although it was used for about one year at 00°C, the coating according to the present invention did not peel off and was running well.

Example 2 N1CrAIY was sprayed under reduced pressure to a thickness of 0.15+nm as an underlay layer on the inner surface of the combustor of the gas star hin for power generation of Example 1, and test pieces No. 003, No. 4, No.
The combustor inner cylinder was made of the same material as No. 10 and 0.3+n+n plasma sprayed in the atmosphere, and the combustion chamber temperature was 1150 to 1300.
After being used for one year at ℃, the coatings No. 10 of the present invention were both healthy and performing well. Incidentally, the coatings of No. 083, No. 4, which were used as comparative materials in this example, all developed hexagonal cracks and peeling within 3 to 6 months.

[Effects of the Invention] As is clear from the above results, the thermal spray coating material of the present invention has extremely high resistance to heat and thermal shock, and has excellent mechanical strength. By using a coating layer sprayed with the thermal spray coating material of the present invention, it is possible to obtain a highly reliable and highly efficient turbine blade that has excellent heat shielding effects and heat resistance, and does not use rare earth oxides. This has the effect of greatly contributing to cost reduction.

[Brief explanation of drawings]

Figure 1 shows 2 Mg (lsio2-75wt96Mgo
・4 This is a cross-sectional photograph showing the crystal structure of a Zr02 (composite raw material) sprayed coating.

Claims (5)

[Claims] 1.2MgO・SiO_2-MgO・4ZrO_2-based oxide, the composition is 20≦2MgO・SiO_ in weight%
2≦50, 50≦MgO・4ZrO_2≦80, and 2
A thermal spray coating material comprising MgO.SiO_2+MgO.4ZrO_2=100. 2. In a component made of a heat-resistant metal material, the component has a metal coating layer provided on its surface that is equivalent to or has higher high-temperature corrosion resistance than the heat-resistant metal material, and further provided on the metal coating layer as claimed in claim 1. A thermal spray coated heat-resistant member characterized by being thermally sprayed with the thermal spray coating material described above. 3. A material for thermal spray coating, wherein each of the oxide materials according to claim 1 is a particle of a compound, a composite, or a mixture. 4. The particle size of the oxide material according to claim 1 is 5 to 500.
A material for thermal spray coating, characterized in that it has an average particle size of 10 to 100 μm. 5. The material for thermal spray coating according to claim 2 is provided in claim 3.
A thermal spray coated heat-resistant member characterized by being the thermal spray coating material according to item 1.