JP5345419B2 - Method for forming high-temperature oxidation ceramic film and substrate with high-temperature oxidation ceramic film - Google Patents

Description

  The present invention relates to a method for forming a ceramic film useful as a technique for improving the high temperature oxidation resistance of a substrate used as a material for a gas turbine, a nuclear power plant, etc., and a ceramic film provided with the ceramic film formed by the method. It relates to a substrate.

  Base materials used in high-temperature and high-pressure environments such as gas turbines and nuclear power plants are required to have high-temperature oxidation resistance (for example, oxidation resistance at 1000 ° C. or higher). And in order to respond | correspond to such a request | requirement, the method of forming films | membranes, such as ceramics which can provide a high temperature oxidation-resistant characteristic on a base material, is examined. As a method for forming a coating of ceramics or the like, plasma spraying or flame spraying is generally employed. In these spraying methods, a coating material heated to a melting point or a softening temperature or higher is used. For example, when carbide ceramic particles such as silicon carbide particles are used, the ceramic particles are decomposed by heat, and a film made of ceramics cannot be formed. It was. In addition, when carbide-based ceramic particles are formed by physical vapor deposition or chemical vapor deposition, these ceramic particles do not decompose, but there is a problem in that the film formation rate is slow and the production efficiency is poor. .

Japanese Patent Application Laid-Open No. 2004-307968 (Patent Document 1) discloses an alloy of Cr, Mo and Ni and at least one selected from the group consisting of TiB ₂ , CrB ₂ , TiC, TiN, WC and Cr ₃ C _2. A method of forming a spray powder by a cold spray method using two ceramic spray powders is disclosed. Furthermore, JP 2008-231527 A (Patent Document 2) discloses a method of forming a spray powder by a cold spray method using a spray powder containing cermet particles made of tungsten carbide and metal. . However, the film formed by the method for forming a film as described in Patent Documents 1 and 2 cannot impart sufficient high-temperature oxidation resistance to the substrate.

JP 2004-307968 A JP 2008-231527 A

  The present invention has been made in view of the above-described problems of the prior art, and a method for forming a ceramic film capable of imparting sufficient high-temperature oxidation resistance to a substrate, and a ceramic formed by the method. It aims at providing the base material with a ceramic membrane | film | coat provided with a membrane | film | coat.

  As a result of intensive studies to achieve the above object, the present inventors have developed a spray powder containing ceramic particles having a ceramic content of 99% by mass or more, instead of particles containing ceramics and metal. Even when the spray powder is formed into a film by the cold spray method, it is surprisingly possible to form a ceramic film having sufficient toughness, and the obtained ceramic film has a sufficient resistance to the substrate. The present inventors have found that high temperature oxidation characteristics can be imparted and have completed the present invention.

That is, in the method for forming a high temperature oxidation-resistant ceramic film of the present invention, the ceramic content is 99% by mass or more , the ceramic is silicon carbide, and the average particle size (mass 50% particle size) is 5 to 5. Using the spray powder made of ceramic particles having a thickness of 30 μm, the spray powder is formed by a cold spray method under the condition that the working gas pressure is in the range of 0.5 to 1 MPa, and the ceramic content is 99 mass. % Or more ceramic film is formed.

Moreover, in the formation method of the high temperature oxidation-resistant ceramic film of this invention, it is preferable to form the said ceramic film on the base material containing molybdenum .

High-temperature substrate with oxidation ceramic coating of the present invention, the comprising: a substrate and a high-temperature oxidation ceramic coating formed on the substrate by the method of forming the high-temperature oxidation ceramic coating of the present invention To do.

Moreover, in the base material with a high temperature oxidation-resistant ceramic film of the present invention, the base material preferably contains molybdenum.

  Although the reason why a ceramic film capable of imparting sufficient high-temperature oxidation resistance to a substrate can be formed by the method for forming a ceramic film of the present invention is not necessarily clear, the present inventors We infer as follows. In other words, a chemically stable ceramic film is densely formed by the method of forming a ceramic film of the present invention, and high-temperature oxidation characteristics are imparted to the substrate by blocking the supply of oxygen from the surface of the ceramic film. . On the other hand, in the conventional method for forming a film, it is common to use metal particles as a binder for reasons such as improving the adhesion efficiency. It is presumed that the high-temperature oxidation becomes a nucleus and the high-temperature oxidation of the substrate proceeds through the metal particles. Thus, in the method for forming a ceramic film according to the present invention, a dense ceramic film having an extremely high content of chemically stable ceramics can be formed, and a metal that becomes a nucleus of high-temperature oxidation in the ceramic film. The present inventors speculate that since there are almost no particles, sufficient high-temperature oxidation resistance can be imparted to the substrate.

  According to the present invention, it is possible to provide a method for forming a ceramic film capable of imparting sufficient high-temperature oxidation resistance to a substrate, and a substrate with a ceramic film provided with a ceramic film formed by the method. It becomes possible.

It is a schematic diagram which shows the cold spray apparatus which can implement suitably the formation method of the ceramic membrane | film | coat of this invention. 2 is an electron micrograph showing a cross section of the ceramic film-coated substrate obtained in Example 1. FIG. It is a graph which shows the relationship between the time of the high temperature oxidation test in the base material with a ceramic membrane | film | coat obtained in Example 1, and the base material for a comparison, and mass variation | change_quantity. It is a graph which shows the X-ray-diffraction spectrum of the base material with a ceramic membrane | film | coat obtained in Example 1 after a high temperature oxidation test, and the base material for a comparison. It is a graph which shows the relationship between the depth from the base-material surface of the base material with a ceramic membrane | film | coat obtained in Example 1 after a high temperature oxidation test, and the element amount of oxygen, silicon, chromium, nickel, and molybdenum. It is a graph which shows the relationship between the depth from the base-material surface of the base material for a comparison after a high temperature oxidation test, and the element amount of oxygen, silicon, chromium, nickel, and molybdenum.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  First, a method for forming a ceramic film of the present invention will be described. That is, in the method for forming a ceramic film of the present invention, the spray powder containing ceramic particles having a ceramic content of 99% by mass or more is used to form the spray powder by a cold spray method, thereby containing the ceramic. It is a method characterized by forming a ceramic film having a rate of 99% by mass or more.

  The ceramic particles used in the present invention are particles having a ceramic content of 99% by mass or more. When the content of the ceramic is less than 99% by mass, the high temperature oxidation resistance in the resulting ceramic film is insufficient. Further, the content of the ceramic is more preferably 99.9% by mass or more, and particularly preferably 100% by mass, from the viewpoint of high temperature oxidation resistance in the obtained ceramic film. When the ceramic content is less than the lower limit, the presence of impurities serves as a transmission path for oxygen ions, and oxygen ions are transmitted to the surface of the base metal, which tends to cause high-temperature oxidation.

The average particle diameter (mass 50% particle diameter: D ₅₀ ) of the ceramic particles is preferably 5 to 30 μm, and more preferably 10 to 20 μm. If the average particle size is less than the lower limit, the particles accelerated during spraying tend to decelerate, so the deposition rate of the ceramic film tends to decrease.On the other hand, if the upper limit is exceeded, the particles are accelerated during spraying. Since it becomes difficult, the deposition rate of the ceramic film tends to decrease.

Ceramics used in the present invention include carbide ceramics such as silicon carbide (SiC) and titanium carbide (TiC); nitride ceramics such as silicon nitride (Si ₃ N ₄ ) and aluminum nitride (AlN); silicon oxide (SiO ₂ ), oxide ceramics such as aluminum oxide (Al ₂ O ₃ ) and chromium oxide (Cr ₂ O ₃ ). Among these ceramics, SiC, Si ₃ N ₄ , SiO ₂ , AlN, Al ₂ O ₃ , and Cr ₂ O ₃ are more preferable, and SiC and SiO ₂ are particularly preferable from the viewpoint of high-temperature oxidation resistance in the obtained ceramic film. preferable. These ceramics can be used individually by 1 type or in combination of 2 or more types. In the present invention, since a film can be formed even with ceramics that are easily decomposed by heat, ceramics that are easily decomposed by heat can be used. For example, carbide ceramics such as SiC and TiC, SiC it can be a _Si 3 _N 4, silicon-containing ceramics such as SiO ₂ to form a suitably coating.

  In the present invention, the spray powder made of the ceramic particles is formed into a film by a cold spray method. The cold spray method refers to a supersonic flow of a gas having a temperature lower than the melting point or softening temperature of the spray powder, the particles of the spray powder are introduced into the supersonic flow gas, and the base material remains in a solid state. It refers to a method of forming a film by colliding with. Hereinafter, such a cold spray method will be described in more detail with reference to the drawings.

  FIG. 1 is a schematic view showing an example of a cold spray apparatus that can suitably carry out the method for forming a ceramic film of the present invention. The cold spray device shown in FIG. 1 includes a gas supply device 1, a gas supply tube 2, a gas heater 3, a working gas supply tube 4, a spray nozzle 5, a spray powder supply device 6, and a spray powder supply tube. 7. In such a cold spray apparatus, the high-pressure gas supplied from the gas supply apparatus 1 passes through the gas supply pipe 2 branched into two paths, and the gas that has passed through one path is supplied to the gas heater 3. The The gas heater 3 is heated to a temperature higher than room temperature and lower than the melting point or softening temperature of the ceramic particles, and then supplied to the spray nozzle 5 through the working gas supply pipe 4. The gas that has passed through the other path is supplied to the spray powder supply device 6, and is supplied to the spray nozzle 5 through the spray powder supply pipe 7 together with the spray powder as a carrier gas. The working gas and spray powder supplied to the spray nozzle 5 in this way become a supersonic flow in the spray nozzle 5 and are ejected from the tip of the spray nozzle 5.

  Although it does not specifically limit as gas supplied from the gas supply apparatus 1, For example, air, nitrogen, and helium can be used. Moreover, it is preferable to adjust the pressure of the gas supplied from the gas supply apparatus 1 so that the pressure of the working gas supplied to the spray nozzle 5 may be in the range of 0.3 to 2 MPa, and the range of 0.5 to 1 MPa. It is more preferable to adjust so that. When the pressure is less than the lower limit, the speed of the particles tends to be insufficient. On the other hand, when the pressure exceeds the upper limit, the particles tend to rebound on the surface of the base material and hardly form a ceramic film. Moreover, since the temperature of the gas in the gas heater 3 varies depending on the type of ceramic particles to be used, it can be appropriately set, but is usually in the range of 100 to 800 ° C, preferably in the range of 300 ° C or higher. . Furthermore, it is preferable that the distance from the front-end | tip of the spray nozzle 5 to the said base material is the range of 10-20 mm. Moreover, the supply speed | rate of the ceramic particle in the ceramic particle supply apparatus 6 is the range of 5-20 g / min normally.

  In the present invention, a spray powder composed of the ceramic particles is deposited by the cold spray method to form a ceramic film having a ceramic content of 99% by mass or more. The ceramic film thus formed has a ceramic content of 99% by mass or more, and contains almost no metal component that oxidizes under high temperature and high pressure conditions. Therefore, in such a ceramic film, since the influence of deterioration due to oxidation of the film is small even under high-temperature and high-pressure conditions, sufficient high-temperature oxidation resistance can be imparted to the substrate.

  The thickness of the ceramic film formed in this way is preferably in the range of 2 to 10 μm. If the thickness is less than the lower limit, it tends to be difficult to impart sufficient high-temperature oxidation resistance to the substrate. On the other hand, if the thickness exceeds the upper limit, the possibility that the film peels tends to increase. In addition, when forming the spray powder made of the ceramic particles by the cold spray method, the ceramic particles collide with each other in a supersonic flow gas, so that nanocrystal particles having an average particle diameter of 50 to 500 nm It becomes. And it is guessed that the said ceramic membrane | film | coat is formed when such a nanocrystal particle deposits on a base material.

  Next, the substrate with a ceramic film of the present invention will be described. That is, the base material with a ceramic film of the present invention comprises a base material and a ceramic film formed on the base material by the method for forming a ceramic film of the present invention. And since the base material with a ceramic film of this invention is equipped with the ceramic film formed by the formation method of the said ceramic film of this invention which can provide sufficient high temperature oxidation-resistant characteristic with respect to a base material, it is enough It has excellent high temperature oxidation resistance.

The material of the substrate used in the present invention is not particularly limited, and may be a metal or a ceramic. Among these, it is preferable to use a metal from the viewpoint of adhesion between the base material and the ceramic film in the obtained base material with a ceramic film, and from the viewpoint of high temperature oxidation resistance of the base material with the ceramic film obtained. Is preferably ceramics. Further, when the material of the ceramic film formed by the method for forming a ceramic film of the present invention is SiC or SiO ₂ , the viewpoint of further improving the high temperature oxidation resistance of the obtained substrate with a ceramic film Therefore, it is more preferable that the base material contains molybdenum.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.

Example 1
Using the cold spray apparatus shown in FIG. 1, a film made of silicon carbide particles was formed on a substrate. That is, as a base material, a nickel base superalloy (made by Special Metal, “Inconel 625”, Ni content: 58 mass%, Cr content: 20 mass%, Fe content: 6 mass%, Mo content: 8 mass%, Nb Using a base material (size: 31 mm × 13 mm × 4 mm) composed of 3.15% by mass and Co content: 1% by mass, and using silicon carbide water-resistant paper (product number: # 600) for the base material Surface treatment. As the silicon carbide particles, powder having an average particle diameter (D ₅₀ ) of 16.9 μm was used. And the film | membrane which consists of silicon carbide particles was formed on the base material on the conditions shown below using the cold spray apparatus shown in FIG. 1, and the base material with a ceramic membrane | film | coat was obtained.
Distance from tip of spray nozzle to substrate: 15mm
Working gas: Supply pressure of air working gas: 0.5 MPa
Working gas supply temperature: 300 ° C
Supply rate of ceramic particles: 10 g / min.

  Moreover, the cross section of the obtained film was observed with a scanning microscope (SEM). The obtained results are shown in FIG. In observing the cross section of the film, a sample in which the surface of the film was further covered with copper was used so that the film made of silicon carbide particles was not peeled off. As is clear from the results shown in FIG. 2, it was confirmed that a film made of silicon carbide particles was formed on the surface of the base material made of nickel-base superalloy. The average thickness of the film was 3 μm. Furthermore, when X-ray diffraction (XRD) analysis of the obtained film was performed, it was confirmed that the film was formed without the silicon carbide particles being decomposed.

<High temperature oxidation test>
The base material (Reference Example 1, size: 31 mm × 13 mm × 4 mm) made of the ceramic film-coated base material obtained in Example 1 and a nickel-base superalloy for comparison was used as a sample in the atmosphere at a temperature of 1000 ° C. A high temperature oxidation test was conducted in which the sample was oxidized under the conditions. That is, first, a sample whose initial mass was measured in advance was prepared, and the sample was subjected to a high-temperature oxidation test for 2 hours in the atmosphere at a temperature of 1000 ° C. Next, the mass of the sample after the high-temperature oxidation test was measured, and the amount of mass change per unit volume (unit: mg / cm ³ ) relative to the initial mass of the sample was calculated from the obtained measurement value. In addition, about the mass of the sample after a high temperature oxidation test, mass was measured after leaving to stand at room temperature (25 degreeC) for 2 hours before a measurement. For the sample after the high-temperature oxidation test of 20 hours, 48 hours, 72 hours, 96 hours, and 188 hours in cumulative time, the mass change amount per volume with respect to the initial mass of the sample was determined in the same manner as described above. Calculated. In addition, the amount of mass change was measured about each two samples, and the average value was computed. In addition, the sample after the high-temperature oxidation test was performed at 900 ° C. and the high-temperature oxidation test was performed for a cumulative time of 48 hours, 84 hours, 132 hours, 196 hours, and 312 hours. The amount of mass change per volume relative to the initial mass of was calculated. The obtained results are shown in FIG. As is apparent from the results shown in FIG. 3, when the ceramic film was formed using the method for forming a ceramic film of the present invention (Example 1), the mass was higher than the base material for comparison (Reference Example 1). It was confirmed that the amount of change was small and sufficient high-temperature oxidation resistance could be imparted to a substrate made of a nickel-base superalloy.

<Analysis by X-ray diffraction of the substrate with ceramic film after high temperature oxidation test>
A high-temperature oxidation test for 65 hours was performed on the base material made of the ceramic coating obtained in Example 1 and a base material made of a nickel-base superalloy for comparison (Reference Example 1) at 1000 ° C. in the atmosphere. The sample was analyzed using X-ray diffraction. That is, first, an X-ray diffraction spectrum of a sample was measured using an X-ray diffractometer (manufactured by Mac Science), and the compound was identified by X-ray diffraction. The obtained results are shown in FIG. As apparent from the results shown in FIG. 4, in the X-ray diffraction spectrum of the substrate with the ceramic coating of the present invention (Example 1), the X-ray diffraction spectrum of the substrate for comparison (Reference Example 1) No peaks of MoSi ₂ and SiO ₂ were observed. From this result, when a film made of silicon carbide particles is formed on a substrate containing molybdenum and subjected to a high temperature oxidation test, MoSi ₂ and SiO ₂ are formed on the surface of the substrate, and these are oxygen diffused. It is assumed that it acts as a barrier.

Next, line analysis of the sample is performed using an energy dispersive X-ray spectrometer (EDX, manufactured by EDAX), and the depth (position) from the sample surface and the element amounts of oxygen, silicon, chromium, nickel and molybdenum A graph showing the relationship with (strength) was created. The result obtained about the base material with a ceramic film obtained in Example 1 is shown in FIG. Moreover, the result obtained about the base material for the comparison which has not formed the ceramic membrane | film | coat is shown in FIG. As is clear from the results shown in FIG. 5 and FIG. 6, in the base material for comparison in which the ceramic film was not formed, chromium was present in the vicinity of the interface between the base material and the oxide formed on the base material surface. It was found that there was a depleted area. On the other hand, in the base material with a ceramic film of the present invention (Example 1), it was recognized that there was no region depleted of chromium and there was a region enriched with silicon and molybdenum. From this result, when a film made of silicon carbide particles is formed on a substrate containing molybdenum and subjected to a high temperature oxidation test, MoSi ₂ and SiO ₂ are formed on the surface of the substrate. It is presumed that chromium depletion near the interface between the substrate and the oxide formed on the substrate surface is suppressed.

  As described above, according to the present invention, it is possible to provide a method for forming a ceramic film capable of imparting sufficient high-temperature oxidation resistance to a substrate.

  Therefore, the method for forming a ceramic film of the present invention is useful as a technique for improving the high temperature oxidation resistance of a base material used as a material for a gas turbine, a nuclear power plant or the like.

  DESCRIPTION OF SYMBOLS 1 ... Gas supply apparatus, 2 ... Gas supply pipe, 3 ... Gas heater, 4 ... Working gas supply pipe, 5 ... Spray nozzle, 6 ... Spray powder supply apparatus, 7 ... Spray powder supply pipe.

Claims (4)

Using a spray powder comprising ceramic particles having a ceramic content of 99% by mass or more , the ceramics being silicon carbide, and an average particle size (mass 50% particle size) of 5 to 30 μm , cold spray is used. by depositing the spray powder under the condition that the pressure of working gas is in the range of 0.5~1MPa by law, high temperature the content of the ceramic is characterized by forming a 99% by mass or more of the ceramic coating A method for forming an oxide ceramic film. The method for forming a high temperature oxidation-resistant ceramic film according to claim 1, wherein the ceramic film is formed on a substrate containing molybdenum . A substrate, according to claim 1 or high-temperature oxidation ceramic coating with the base material, characterized in that it comprises a high-temperature oxidation ceramic coating formed on the substrate by the method of forming the high-temperature oxidation ceramic coating according to 2 . The said base material contains molybdenum, The base material with a high temperature oxidation-resistant ceramic membrane | film | coat of Claim 3 characterized by the above-mentioned.