JP6216219B2 - Thermal insulation structure - Google Patents

Description

  The present invention relates to a heat shield structure including a layer structure having resistance to a high temperature up to about 1,600 ° C.

  In a gas turbine engine for power generation, an aircraft jet engine, and the like, the temperature of the combustion gas is known to be as high as 1,600 ° C., for example. Therefore, high-temperature parts such as rotor blades, stationary blades, and combustors have MCrAlY alloys (provided that they have excellent corrosion resistance and oxidation resistance) on the surface of a metal substrate made of a superalloy mainly composed of Ni, Co, or Fe. , M is at least one of Ni, Co and Fe) or a metal binding layer made of platinum aluminide and a thermal barrier layer (thermal barrier coating layer) mainly composed of ceramics such as yttria-stabilized zirconia. The one having the structure is generally used. The thermal barrier layer suppresses the temperature rise of the metal substrate, the metal bonding layer reduces the thermal stress generated between the metal substrate and the thermal barrier layer, and further suppresses the corrosion or oxidation of the metal substrate. Is done. The metal base and the metal bonding layer may be collectively referred to as a heat resistant metal base.

Yttria-stabilized zirconia, for example, has excellent resistance to stress and fatigue when the temperature is increased or decreased from start to stop of a gas turbine, but in recent years, the search for a material that provides lower thermal conductivity than yttria-stabilized zirconia Has been done.
Patent Document 1 discloses a metal object having a film containing a compound having a pyrochlore structure represented by A ₂ B ₂ O ₇ (such as La ₂ Zr ₂ O ₇ ).
Patent Document 2 discloses a thermal barrier coating member having a thermal barrier layer made of a ceramic obtained by adding 0.1 to 10 mol% of lanthanum oxide to rare earth stabilized zirconia and rare earth stabilized zirconia-hafnia.
In Patent Document 3, it is represented by Ln ₃ Nb _1-x Ta _x O ₇ (0 ≦ x ≦ 1, Ln is one or more atoms selected from the group consisting of Sc, Y and lanthanoid). A thermal barrier coating material mainly comprising a compound is disclosed.
In Patent Document 4, Ln _1-x M _x O _{1.5 + x} (0.13 ≦ x ≦ 0.24, Ln is one or more atoms selected from the group consisting of Sc, Y and lanthanoids, A thermal barrier coating material mainly containing a compound represented by M being Ta or Nb) is disclosed.
Further, Patent Document _{5, Ln x + y-3xy} Ti x Ta x Zr (1-3x) (1-y) O 2 + 1.5xy-0.5y (0.05 ≦ x ≦ 0.25,0 ≦ y ≦ 0.15, Ln is a thermal barrier coating material mainly containing one or more atoms selected from the group consisting of Y, Sm, Yb and Nd).

Japanese Patent Laid-Open No. 10-212108 JP 2004-270032 A JP 2006-298695 A JP 2009-221551A JP 2010-235415 A

When the refractory metal substrate is made of MCrAlY alloy (where M is at least one of Ni, Co and Fe) or platinum aluminide, when the heat shield layer is disposed, It is known that an aluminum oxide layer (alumina scale) is formed. Further, oxide transformation (for example, YTa ₃ O ₉ in FIG. 5) at the time of forming the thermal barrier layer (sintering, etc.), thermal expansion difference between the thermal barrier layer and the refractory metal substrate, and further, a refractory metal It is also known that the thermal barrier layer may be broken or peeled off due to volume expansion due to oxidation of the base material. Under these circumstances, there is an increasing demand for higher resistance to high-temperature components (heat-resistant components) having a heat shield layer, and in particular, high stability is required between the aluminum oxide layer and the heat shield layer. .

  The object of the present invention is to provide a layer adjacent to the aluminum oxide layer even at a high temperature up to about 1600 ° C., and further, a layer adjacent to each other when a new layer is formed on the surface of the aluminum oxide layer. It is intended to provide a thermally stable heat shielding structure in which reaction between materials constituting the material is suppressed.

The present invention is shown below.
1. A refractory metal substrate, a heat-resistant metal substrate of aluminum oxide layer formed on the surface of a first layer comprising a YTaO ₄ doped zirconia formed on the surface of the aluminum oxide layer, on the surface of the first layer And a formed second layer containing a compound (B) represented by the following general formula (11) .
Ta _1-4x Zr _{2.75 + 5x} O ₈ (11)
(Wherein x is -0.021 to 0.069)
2 . Furthermore, on the surface of the second layer, when the total of the compound (B) and the compound (C) represented by the following general formula (21) is 100% by volume, 2. The heat shielding structure according to 1 above, comprising a third layer containing 70% by volume and 30 to 70% by volume.
Y _{1 + y} Ta _3-3y Zr _3y O ₉ (21)
(In the formula, y is 0.05 to 0.10.)
3 . 3. The heat shielding structure according to 1 or 2 above, wherein the refractory metal substrate is MCrAlY (M is at least one atom selected from Ni, Co, and Fe).

The thermal barrier structure of the present invention includes a first layer containing YTaO ₄ doped zirconia that has a lower thermal conductivity than yttria-stabilized zirconia and is less likely to cause phase transformation. Therefore, at a high temperature up to about 1,600 ° C. The layer structure is stable, and this structure is suitable for application to a combustor in an aircraft jet engine, a high-temperature component in a power generation gas turbine, and other high-temperature components in various plants.
In particular, the compound (B) represented by the general formula (11) and the compound (C) represented by the general formula (21) are both phased by temperature increase or decrease in temperature in the range of 25 ° C to 1,200 ° C. Since the transformation hardly occurs, the melting point is as high as 1,700 ° C. or higher, and it is thermally stable, it provides a heat shielding structure having a layer structure having excellent heat resistance.

It is a schematic sectional drawing which shows an example of the heat insulation structure which is not included in this invention. It is a schematic sectional drawing which shows the other example of the heat insulation structure of this invention. It is a schematic sectional drawing which shows the other example of the heat insulation structure of this invention. It is a graph which shows heat conductivity, such as complex oxide used in an example of an experiment. It is a graph which shows the linear expansion coefficient of complex oxide etc. which are used in an experiment example. It is an X-ray diffraction image before and after preparation of the heat-treated product obtained in Test Example 1. It is an X-ray diffraction image before and after preparation of the heat-treated product obtained in Test Example 2. It is an X-ray diffraction image before and after preparation of the heat-treated product obtained in Test Example 3. It is an X-ray diffraction image before and after preparation of the heat-treated product obtained in Test Example 4. It is an X-ray diffraction image before and after preparation of the heat-treated product obtained in Test Example 5. It is an X-ray diffraction image before and after preparation of the heat-treated product obtained in Test Example 6. It is an X-ray diffraction image before and after preparation of the heat-treated product obtained in Test Example 7. 2 is a cross-sectional image of a laminate obtained in Experimental Example 1 and element profiles of Al and Ta. 5 is a cross-sectional image of a laminate obtained in Experimental Example 2 and an element profile of Ta. 10 is a cross-sectional image of a laminate obtained in Experimental Example 3 and an element profile of Ta.

1. Thermal structure shielding the heat insulating structure present invention has a plurality of inorganic material layer is laminated on the surface of the refractory metal substrate, the cross-section is shown in FIG. That is, the heat shield structure 10 of FIG. 2 includes a heat-resistant metal substrate 11, an aluminum oxide layer 13 formed on the surface of the heat-resistant metal substrate 11, and YTaO ₄ -doped zirconia ( Hereinafter, the first layer 15 containing the compound (A) ) and the second layer 17 containing the compound (B) represented by the general formula (11) formed on the surface of the first layer 15. With . In addition, as shown in FIG. 3, the heat-insulating structure of the present invention comprises the compound (B) and the compound (C) represented by the general formula (21) on the surface of the second layer 17. When the content is 100% by volume, a third layer containing 30 to 70% by volume and 30 to 70% by volume can be provided.

1-1. Refractory metal substrate The refractory metal substrate may be either a single material or a laminate, and a metal having a melting point of 1,200 ° C. or higher at the contact surface with the aluminum oxide layer (the outermost layer in the case of a laminate) It is preferable to include an alloy. As such an inorganic material, for example, an Fe-based alloy, a Ni-based alloy, a Co-based alloy, an aluminide-type alloy, or the like can be used. Specifically, an MCrAlY alloy (where M is a combination of Ni, Co, and Fe). At least one), platinum aluminide, nickel-platinum-aluminide, and the like. Of these, MCrAlY alloys are preferred from the viewpoint of heat resistance. The material constituting the base when the refractory metal substrate is a laminate is preferably selected from Ni, Co, Fe, Nb, Ta, Mo, W, Pt, Ir, Cr, Al, and the like. It is an alloy composed of at least one metal or at least two kinds.

1-2. Aluminum oxide layer Aluminum oxide constituting the aluminum oxide layer may be any of α-alumina, β-alumina, γ-alumina, σ-alumina, χ-alumina, η-alumina, θ-alumina and κ-alumina. A combination of two or more of them may be used. In the present invention, α-alumina is preferable from the viewpoints of stability at high temperatures, oxygen shielding properties, and the like.

The aluminum oxide layer is preferably made of only aluminum oxide, but other compounds made of NiAl ₂ O ₄ , (Co, Ni) (Al, Cr) ₂ O _4, etc. within the range where the effects of the present invention can be obtained. May be included. In that case, the upper limit of the content ratio of the other compound is preferably 5% by volume, more preferably 1% by volume when the constituent material of the aluminum oxide layer is 100% by volume.

  Although the thickness of the said aluminum oxide layer is not specifically limited, From viewpoints, such as heat cycle tolerance, Preferably it is 0.5-10 micrometers, More preferably, it is 0.5-5 micrometers, More preferably, it is 0.5-2 micrometers.

1-3. First layer The first layer is a layer containing YTaO ₄ doped zirconia (compound (A)), and the content ratio of the compound (A) is preferably 70 to 100% by volume with respect to the entire first layer, More preferably, it is 90-100 volume%.
The compound (A) is a compound obtained by stabilizing cubic zirconia by dissolving YTaO ₄ in zirconia. Moreover, this compound (A) is stable with the aluminum oxide which contacts in the high temperature to about 1600 degreeC. The content ratio of YTaO ₄ is preferably 10 to 30 mol%, more preferably 12 to 25 mol%, based on the entire compound (A). In addition, since a cubic (zirconia) single phase is maintained favorably, it is more preferably 14 to 20 mol%, and since lower thermal conductivity is obtained, it is particularly preferably 16 to 20 mol%.

The melting point of the compound (A) is usually 1,700 ° C. or higher, and thermal conductivity (measurement temperature: 25 ° C. to 1,000 ° C.) measured by a laser flash method in accordance with JIS R1611 is preferable. Is less than 2.0 W / (m · K), more preferably less than 1.8 W / (m · K).
Further, the compound (A) is subjected to thermomechanical analysis, and in a range of room temperature (25 ° C.) to 1,200 ° C. with a constant rate of temperature increase and decrease in an atmosphere of air, oxygen gas, argon gas, etc. It is a thermally stable compound with no phase transformation that can be confirmed by the behavior of linear expansion coefficient obtained by measuring the dimensional change by the compression load method after heating and cooling. The linear expansion coefficient obtained by this method can be less than 10.00 × 10 ⁻⁶ (1 / ° C.).

  The compound (A) contained in the first layer may be only one type or two or more types.

  The first layer is preferably a layer made of only the compound (A), but when it contains other compounds, for example, aluminum oxide or the like can be used.

1-4. Second Layer The second layer is a layer containing the compound (B) represented by the following general formula (11), and the content ratio of the compound (B) is preferably 70 with respect to the entire second layer. -100 volume%, More preferably, it is 90-100 volume%.
Ta _1-4x Zr _{2.75 + 5x} O ₈ (11)
(Wherein x is -0.021 to 0.069)

The compound (B) is stable with the compound (A) at a high temperature up to about 1,600 ° C., and is prevented from being broken, peeled off or the like in a laminated structure including the first layer and the second layer sequentially. And excellent heat resistance can be obtained.
The crystal structure of the compound (B) is not clear, but is said to be deficient from the ABO ₄ type structure.

In the general formula (11), x is −0.021 to 0.069, preferably −0.010 to 0.020, more preferably −0.01 to 0.010, and particularly preferably 0. is there.
When x is in the above range, the composite compound is unlikely to undergo phase transformation due to temperature rise or temperature fall in the range of 25 ° C. to 1,200 ° C., and volume change associated with phase transformation is suppressed. Thereby, in the 2nd layer containing the said compound (B), malfunctions, such as a deformation | transformation accompanying a volume change and a fracture | rupture, can be suppressed especially in the temperature of the said range.

The melting point of the compound (B) is usually 1,700 ° C. or higher, and thermal conductivity (measurement temperature: 25 ° C. to 1,000 ° C.) measured by a laser flash method in accordance with JIS R1611 is preferable. Is less than 2.0 W / (m · K), more preferably less than 1.8 W / (m · K).
Furthermore, when the compound (B) is subjected to thermomechanical analysis, the phase transformation that can be confirmed by the above method is not observed, and the compound (B) is a thermally stable compound. And the linear expansion coefficient obtained by this method can be less than 9.50 × 10 ⁻⁶ (1 / ° C.).

  The compound (B) contained in the second layer may be only one type or two or more types.

  The second layer is preferably a layer made of only the compound (B), but when other compounds are included, for example, aluminum oxide or the like can be used.

1-5. Third Layer The third layer is a layer containing the compound (B) and the compound (C) represented by the following general formula (21) at a predetermined ratio. The third layer is preferably made of these compounds, but may contain other compounds (described later) as necessary. In that case, the upper limit of the content ratio of the other compound is preferably 30% by volume, more preferably 10% by volume with respect to the entire third layer.
Y _{1 + y} Ta _3-3y Zr _3y O ₉ (21)
(In the formula, y is 0.05 to 0.10.)

The compound (C) is stable together with the coexisting compound (B) at a high temperature up to about 1,600 ° C., and is broken in the laminated structure comprising the first layer, the second layer, and the third layer sequentially. , Peeling and the like are suppressed, and excellent heat resistance can be obtained.
The compound (C) is a cation-deficient defect perovskite complex oxide. The structure of this compound is a structure in which 2/3 A ions are lost from the perovskite structure represented by A ₃ B ₃ O ₉ .
The compound (C) has a structure in which a Y atom is contained in the A site and the x mark, and a Ta atom and a Zr atom are contained in the B site.

In the general formula (21), y is 0.05 to 0.10, preferably 0.06 to 0.09, more preferably 0.07 to 0.08, and particularly preferably 0.08. .
When y is in the above range, the composite compound is unlikely to undergo phase transformation due to temperature rise or temperature fall in the range of 25 ° C. to 1,200 ° C., and volume change associated with phase transformation is suppressed. Thereby, in the 3rd layer containing the said compounds (B) and (C), troubles, such as a deformation | transformation accompanying a volume change and a fracture | rupture, can be suppressed especially in the temperature of the said range.

The melting point of the compound (C) is usually 1,700 ° C. or higher, and thermal conductivity (measurement temperature: 25 ° C. to 1,000 ° C.) measured by a laser flash method in accordance with JIS R1611 is preferable. Is less than 2.0 W / (m · K), more preferably less than 1.8 W / (m · K).
Furthermore, when the compound (C) is subjected to thermomechanical analysis, the phase transformation that can be confirmed by the above method is not observed, and the compound (C) is a thermally stable compound. The linear expansion coefficient obtained by this method can be less than 9.00 × 10 ⁻⁶ (1 / ° C.).

  Each of the compounds (B) and (C) contained in the third layer may be only one type or two or more types.

  The content ratio of the compounds (B) and (C) contained in the third layer is such that both are stably present at a high temperature up to about 1600 ° C., and low thermal conductivity is obtained. Is 100 to 30% by volume, respectively, preferably 30 to 70% by volume and 30 to 70% by volume, preferably 40 to 60% by volume and 40 to 60% by volume, more preferably 45 to 55% by volume and 45 to 45% by volume. It is 55 volume%, More preferably, it is 48-52 volume% and 48-52 volume%.

  The third layer is preferably a layer composed only of the compounds (B) and (C). However, when other compounds are included, for example, aluminum oxide or the like can be used.

1-6. Thickness of each layer The thickness of each layer which comprises the heat-insulating structure of this invention is suitably selected according to the objective, a use, etc. Hereinafter, preferable thicknesses in the case of a heat shield structure provided for an industrial member such as a moving blade of a power generation gas turbine are shown.
In the case of the embodiment of FIG. 2, the thicknesses of the first layer and the second layer are preferably 1 to 10 μm and 1 to 10 μm, more preferably 5 to 10 μm and 5 to 10 μm, and still more preferably 8 to 10 μm and 8 respectively. 10 μm.
In the case of FIG. 3, the thicknesses of the first layer, the second layer, and the third layer are preferably 1 to 10 μm, 1 to 10 μm, and 1 to 10 μm, more preferably 5 to 10 μm, and 5 to 5, respectively. They are 10 micrometers and 5-10 micrometers, More preferably, they are 8-10 micrometers, 8-10 micrometers, and 8-10 micrometers.

  The heat shield structure of the present invention comprises an aluminum oxide layer, a first layer, a second layer, and a third layer sequentially on the surface of the refractory metal substrate. Since the generated thermal stress can be relaxed, the durability of the heat shield structure can be further improved.

2. Method for Producing Thermal Barrier Structure The method for producing the thermal barrier structure of the present invention is not particularly limited.
The heat-resistant metal base material is a material containing an Al element (Fe-base alloy, Ni-base alloy, Co-base alloy, aluminide-type alloy, etc.), and aluminum oxide is formed on the surface of the heat-resistant metal base by the first layer forming method described later. In the case where it is made of an alumina former type heat-resistant alloy (preferably MCrAlY alloy, platinum aluminide, nickel-platinum-aluminide, etc.), the first layer forming raw material is used on its surface, The first layer is formed by using a method such as electron beam physical vapor deposition (EB-PVD), plasma spraying, vacuum plasma spraying, flame spraying, high-speed spraying, sintering, and the like. An aluminum oxide layer can be formed at the interface of the layers. Thereafter, using the second layer forming raw material and the third layer forming raw material on the surface of the first layer, respectively, electron beam physical vapor deposition (EB-PVD), plasma spraying, vacuum plasma spraying, flame spraying By applying to a method such as high-speed thermal spraying and sintering, a heat shield structure can be manufactured. In this case, the first layer, the second layer, and the third layer may be sequentially formed after the aluminum oxide layer is formed by performing a pre-oxidation treatment or the like on the surface of the refractory metal substrate. Good.
When the refractory metal substrate is made of a material that does not contain an Al element, an aluminum oxide layer is formed by a method such as thermal spraying, and then a first layer forming raw material and a second layer are formed on the surface of the aluminum oxide layer. Using the raw material for forming and the raw material for forming the third layer, respectively, for electron beam physical vapor deposition (EB-PVD), plasma spraying, vacuum plasma spraying, flame spraying, high-speed spraying, sintering, etc. Thus, the first layer, the second layer, and the third layer can be sequentially formed to manufacture the heat shield structure.

  If the aluminum oxide layer is dense, the adhesion with the first layer to be formed is improved, so that the occurrence of delamination during use at a high temperature can be suppressed, and the durability of a product having a heat shield structure Can be further improved.

The first layer forming raw material preferably contains mainly a powder comprising the compound (A), and may further contain an aluminum oxide powder.
The second layer forming raw material preferably contains mainly powder composed of the compound (B), and may further contain aluminum oxide powder.
The third layer forming raw material preferably contains mainly a powder made of the compound (B) and a powder made of the compound (C), and may further contain an aluminum oxide powder.

1. Preparation of Composite Oxide The composite oxides used in each experimental example to be described later are (1) to (4) below, and (1) to (3) are obtained in the following Production Examples 1 to 3, respectively. The fired body thus obtained is pulverized.
(1) YTaO ₄ doped zirconia powder (2) Y _1.08 Ta _2.76 Zr _0.24 O ₉ powder (3) TaZr _2.75 O ₈ powder (4) Yttria stabilized zirconia powder (“Zirconia manufactured by Tosoh Corporation) powder TZ-10Y "(trade _{name, 10mol% Y 2 O 3 -ZrO} 2))

Production Example 1 (Production of YTaO ₄ doped zirconia)
Distilled liquid 700 grams housed in a fluororesin-made reactor, with a purity of 99.99% or more _{Y (NO 3)} (manufactured by Kanto Chemical Co., Inc.) 3 · 6H ₂ O powder 6 g (0.45 mole), purity 99.95% or more of ZrCl ₂ O.8H ₂ O powder (manufactured by Kanto Chemical Co., Inc.) 23 g (1.8 mol) was added and stirred at room temperature (25 ° C.) for 1 hour to give a colorless transparent aqueous solution. Obtained. Next, 530 grams (125 moles) of urea was added to this aqueous solution and stirred at room temperature (25 ° C.) for 1 hour. Thereafter, 3 g (0.2 mol) of Ta ₂ O ₅ powder (manufactured by Rare Metallic) having a purity of 99.9% or more was added to the obtained colorless and transparent aqueous solution and stirred at room temperature (25 ° C.) for 7 hours. To obtain a suspension.
Next, the suspension was heated to 95 ° C. and reacted (urea hydrolysis reaction) with stirring while cooling under reflux (reaction time: 15 hours). Thereafter, the obtained reaction solution was centrifuged at 25 ° C. and 4,800 rpm for 30 minutes to recover the lower layer gel. When this gel was poured into a large amount of distilled water and sufficiently stirred, it was centrifuged under the same conditions as above to recover the lower layer gel. The gel was poured into a large amount of isopropyl alcohol, and when sufficiently stirred, the gel was centrifuged under the same conditions as described above to collect the precipitate.
Thereafter, the precipitate was heated in an air atmosphere at 120 ° C. for 24 hours to obtain a dry powder. The dried powder was then sieved (100 mesh) to collect a fine powder. And this fine powder was used for press molding (pressure 5MPa), and the disk-shaped molded object was produced. Then, this molded object was heat-processed (calcination) for 1 hour at 1,400 degreeC in air | atmosphere atmosphere, and the temporary baking molded object was obtained. The obtained calcined shape was dry-ground with a mortar at room temperature (25 ° C.).
Next, the dry pulverized product was sieved (100 mesh) to collect a fine powder. The fine powder was subjected to press molding (pressure 25 MPa), and further subjected to cold isostatic pressing (load 2.5 tons) to produce a disk-shaped molded body. Thereafter, the compact was heat-treated at 1,650 ° C. for 1 hour in an air atmosphere. The obtained fired body was dry-ground with a mortar at room temperature (25 ° C.) and subjected to X-ray diffraction measurement. As a result, the fired body was substantially 16 mol consisting of a cubic zirconia single phase. % YTaO ₄ —ZrO ₂ was found. Moreover, when the fired body was visually observed, it was confirmed that it was not melted by high-temperature heat treatment at 1,650 ° C.

The thermal conductivity of the YTaO ₄ doped zirconia is known from literatures and the like, and using data cited from MR Winter, et al., J. Am. Ceram. Soc., 90, 533-540 (2007), This is shown in FIG. 4 (indicated as “Y, Ta—ZrO ₂ ” in the figure).

Production Example 2 (Production of Y _1.08 Ta _2.76 Zr _0.24 O ₉ )
Distilled water 900 g were housed in a fluororesin-made reactor, with a purity of 99.99% or more _{Y (NO 3)} (manufactured by Kanto Chemical Co., Inc.) 3 · 6H ₂ O powder 10 grams (0.025 mol), purity 3 g (0.007 mol) of 99.95% or more of ZrCl ₂ O.8H ₂ O powder (manufactured by Kanto Chemical Co., Inc.) was added and stirred at room temperature (25 ° C.) for 1 hour to give a colorless and transparent aqueous solution. Obtained. Next, 90 g (3 mol) of urea was added to this aqueous solution, and the mixture was stirred at room temperature (25 ° C.) for 1 hour. Thereafter, 12 g (0.026 mol) of Ta ₂ O ₅ powder (manufactured by Rare Metallic) having a purity of 99.9% or more was added to the obtained colorless and transparent aqueous solution and stirred at room temperature (25 ° C.) for 7 hours. To obtain a suspension.
Next, the suspension was heated to 95 ° C. and reacted (urea hydrolysis reaction) with stirring while cooling under reflux (reaction time: 15 hours). Thereafter, the obtained reaction solution was centrifuged at 25 ° C. and 4,800 rpm for 30 minutes to recover the lower layer gel. When this gel was poured into a large amount of distilled water and sufficiently stirred, it was centrifuged under the same conditions as above to recover the lower layer gel. The gel was poured into a large amount of isopropyl alcohol, and when sufficiently stirred, the gel was centrifuged under the same conditions as described above to collect the precipitate.
Thereafter, the precipitate was heated in an air atmosphere at 120 ° C. for 24 hours to obtain a dry powder. The dried powder was then sieved (100 mesh) to collect a fine powder. And this fine powder was used for press molding (pressure 5MPa), and the disk-shaped molded object was produced. Then, this molded object was heat-processed (calcination) for 1 hour at 1,400 degreeC in air | atmosphere atmosphere, and the temporary baking molded object was obtained. The obtained calcined shape was dry-ground with a mortar at room temperature (25 ° C.).
Next, the dry pulverized product was sieved (100 mesh) to collect a fine powder. The fine powder was subjected to press molding (pressure 25 MPa), and further subjected to cold isostatic pressing (load 2.5 tons) to produce a disk-shaped molded body. Thereafter, the compact was heat-treated at 1,650 ° C. for 1 hour in an air atmosphere. The obtained fired body was dry-ground with a mortar at room temperature (25 ° C.) and subjected to X-ray diffraction measurement. As a result, the fired body was substantially Y _1.08 Ta _2.76 Zr _0.24 O. It was found to be a tetragonal system consisting of ₉ . Moreover, when the fired body was visually observed, it was confirmed that it was not melted by high-temperature heat treatment at 1,650 ° C.

Further, the fired body was subjected to a laser flash method (based on JIS R1611), and the thermal conductivity at 25 ° C., 200 ° C., 400 ° C., 600 ° C., 800 ° C. and 1,000 ° C. was measured. It is known that the thermal conductivity of a solid is easily affected by the pores of the measurement sample, and has a lower value if it has pores. Therefore, in order to obtain a dense thermal conductivity, it is preferable to use the correction formula (C. Wan, et al., Acta Mater., 58, 6166-6172 (2010)) shown in the following formula (40). It is said.
k ′ / k = 1−4 / 3φ (40)
(K ′: measured thermal conductivity, k: dense thermal conductivity, φ: porosity)
The thermal conductivity at each temperature is shown in FIG. 4 as k corrected by the above equation (40).

In addition, using a thermomechanical analyzer “TMA8310” (model name) manufactured by Rigaku Corporation, heating the fired body in the range of 25 ° C. to 1,200 ° C. in the air at a heating rate and a cooling rate of 10 ° C. per minute. Then, the dimensional change was measured by the compression load method (load: 98 mN), and the linear expansion coefficient was calculated. The result is shown in FIG. Moreover, the linear expansion coefficient in the said temperature range was 8.87 * 10 < ^-6 > / degreeC.

Production Example 3 (Production of TaZr _2.75 O ₈ )
Instead of the combined use of Y (NO ₃ ) ₃ · 6H ₂ O powder and ZrCl ₂ O · 8H ₂ O powder, only 23 grams (1.2 moles) of ZrCl ₂ O · 8H ₂ O powder was used, urea, and A fired body was produced in the same manner as in Production Example 1 except that the amount of Ta ₂ O ₅ powder used was 540 grams (125 moles) and 5 grams (0.2 moles), respectively. Next, X-ray diffraction measurement revealed that the fired body had an ABO ₄ -based defect structure substantially consisting of TaZr _2.75 O ₈ . Moreover, when the fired body was visually observed, it was confirmed that it was not melted by high-temperature heat treatment at 1,650 ° C.
Then, it carried out similarly to manufacture example 2, and calculated | required the thermal conductivity and the linear expansion coefficient. The results are shown in FIGS. Moreover, the linear expansion coefficient in the range of 25 degreeC-1,200 degreeC was 9.19x10 < ^-6 > / degreeC.

  Although the thermal conductivity and linear expansion coefficient of yttria-stabilized zirconia shown in (4) above are not measured, FIG. 4 shows MR Winter, et al., J. Am. Ceram. Soc., 90, Data of yttria-stabilized zirconia (8YSZ) cited from 533-540 (2007) was published.

As is clear from FIG. 4, the compound powders (1) to (3) are found to be lower than the thermal conductivity of yttria-stabilized zirconia in the range of 25 ° C. to 1200 ° C. Further, as apparent from FIG. 5, no phase transformation was confirmed in these compounds (the compound (1) is substantially zirconia, and thus no phase transformation is observed). That is, three compounds of Y _1.08 Ta _2.76 Zr _0.24 O ₉ , TaZr _2.75 O ₈ and YTaO ₄ doped zirconia have excellent heat shielding properties in the range of 25 ° C. to 1,200 ° C. It can be seen that deformation, breakage, and the like associated with the volume change are suppressed and the heat resistance is excellent.

2. Reactivity between compounds In the following test examples, two kinds of compounds were mixed and molded into a predetermined shape. Next, heat treatment was performed at 1,500 ° C. in an air atmosphere. Thereafter, X-ray diffraction measurement of the heat-treated product was performed to examine the reactivity. For comparison, X-ray diffraction measurement was also performed on the mixed powder before heat treatment.

Test example 1
YTaO ₄ doped zirconia powder and α-alumina powder “TM-DAR” (trade name) manufactured by Daimei Chemical Industry Co., Ltd. were mixed at a volume ratio of 1: 1. Subsequently, the mixed powder was subjected to press molding (pressure 25 MPa) to obtain a plate-shaped molded body having a diameter of 15 mm. Then, this plate-shaped molded body was heat-treated (in the air atmosphere, 1,500 ° C.) with an electric furnace “Superburn” (trade name) manufactured by Motoyama. X-ray diffraction images before and after the heat treatment are shown in FIG. 6 (in the figure, YTaO ₄ -doped zirconia is expressed as “Y, Ta—ZrO ₂ ”).
6 (a) and 6 (b), since there is no difference in the X-ray diffraction images before and after the heat treatment, it is expected that the laminate composed of layers containing each compound independently is thermally stable.

Test example 2
A plate-like molded body was obtained in the same manner as in Test Example 1 except that TaZr _2.75 O ₈ powder and the α-alumina powder were mixed at a volume ratio of 1: 1. 1,500 ° C. in the atmosphere). X-ray diffraction images before and after the heat treatment are shown in FIG.
7A and 7B, since a signal derived from AlZr ₂ TaO ₈ was detected by heat treatment, it is expected that the laminate composed of layers containing each compound independently is not thermally stable. Is done.

Test example 3
A plate-like molded body in the same manner as in Test Example 1, except that Y _1.08 Ta _2.76 Zr _0.24 O ₉ powder and the α-alumina powder were mixed at a volume ratio of 1: 1. Then, heat treatment (1,500 ° C. in the air atmosphere) was performed. X-ray diffraction images before and after the heat treatment are shown in FIG.
8 (a) and 8 (b), signals derived from AlZr ₂ TaO ₈ and AlTaO ₄ were detected by the heat treatment, so that the laminate composed of layers containing each compound independently is not thermally stable. It is expected that.

Test example 4
Except that YTaO ₄ -doped zirconia powder and TaZr _2.75 O ₈ powder were mixed at a volume ratio of 1: 1, a plate-like molded body was obtained in the same manner as in Test Example 1, and then heat treatment (atmosphere) Medium, 1500 ° C.). X-ray diffraction images before and after the heat treatment are shown in FIG.
9 (a) and 9 (b), since there is no difference in the X-ray diffraction images before and after the heat treatment, it is expected that the laminate composed of layers containing each compound independently is thermally stable.

Test Example 5
After obtaining a plate-like molded body in the same manner as in Test Example 1 except that YTaO ₄ doped zirconia powder and yttria-stabilized zirconia (YSZ) powder were mixed at a volume ratio of 1: 1, heat treatment (atmosphere 1,500 ° C. in the atmosphere). The X-ray diffraction images before and after the heat treatment are shown in FIG.
10 (a) and 10 (b), since a signal derived from m-ZrO ₂ (monoclinic zirconia) was detected by heat treatment, a laminate composed of layers containing each compound independently was thermally treated. Is not expected to be stable.

Test Example 6
Plate-like molding is performed in the same manner as in Test Example 1 except that TaZr _2.75 O ₈ powder and Y _1.08 Ta _2.76 Zr _0.24 O ₉ powder are mixed at a volume ratio of 1: 1. After obtaining the body, heat treatment (in air atmosphere, 1,500 ° C.) was performed. X-ray diffraction images before and after the heat treatment are shown in FIG.
11 (a) and 11 (b), since there is no difference in the X-ray diffraction images before and after the heat treatment, it is expected that the laminate composed of layers containing each compound independently is thermally stable.

Test Example 7
Except for mixing TaZr _2.75 O ₈ powder and yttria-stabilized zirconia powder at a volume ratio of 1: 1, a plate-like molded body was obtained in the same manner as in Test Example 1, and then heat treatment (atmosphere) Medium, 1500 ° C.). X-ray diffraction images before and after the heat treatment are shown in FIG.
12 (a) and (b), the signal derived from yttria-stabilized zirconia disappeared by heat treatment, and the signal derived from m-ZrO ₂ (monoclinic zirconia) was detected. It is expected that the laminate composed of the layers that are included independently is not thermally stable.

3. Manufacture of laminate and its evaluation As described above, when the heat-resistant metal substrate is made of MCrAlY alloy or platinum aluminide, the heat-resistant metal substrate is disposed when the heat shielding layer is disposed using a composite oxide or the like. Since an aluminum oxide layer (alumina scale) is formed on the outermost surface of the aluminum oxide, in the following experimental example, a layer made of one or two of the above complex oxides is laminated on the surface of the aluminum oxide layer and adjacent to each other. The stability of the layer interface was evaluated.

Experimental example 1
1.1 grams of α-alumina powder “TM-DAR” (trade name) manufactured by Daimei Chemical Industry Co., Ltd. was filled into a molding die having an inner diameter of 15 mm, and lightly compacted with a piston to form a disk. Thereafter, 2.6 g of YTaO ₄ -doped zirconia powder was evenly filled on the surface of the α-alumina layer in a molding die and lightly compacted. Next, the laminate was press-molded at a pressure of 800 kg / cm ² and further CIP-molded at a hydrostatic pressure of 2.5 t / cm ² . Thereafter, the molded body was heat-treated (1,500 ° C. in the air atmosphere) with an electric furnace “Superburn” (trade name) manufactured by Motoyama, and a laminate having a thickness of about 4 mm was obtained.
The obtained laminate was cut near the center, and the cut surface was mirror-polished. Thereafter, observation of the polished surface and energy dispersive X-ray analysis (hereinafter referred to as “EDS analysis”) were performed using an electron microscope “S4500” (model name) manufactured by Hitachi Electronics. The result is shown in FIG. It was found that there was no movement of atoms (Al or Ta) between adjacent layers, and the layer structure was stable.

Experimental example 2
The α-alumina powder “TM-DAR” (trade name) (1.1 gram) was filled in a molding die having an inner diameter of 15 mm, and lightly compressed using a piston to form a disk. Thereafter, 2.6 g of YTaO ₄ -doped zirconia powder was evenly filled on the surface of the α-alumina layer in a molding die and lightly compacted. Next, in the molding die, the surface of this YTaO ₄ -doped zirconia layer was evenly filled with 1.5 g of TaZr _2.75 O ₈ powder and lightly compacted. Thereafter, the laminate was press-molded at a pressure of 800 kg / cm ² and further CIP-molded at a hydrostatic pressure of 2.5 t / cm ² . Next, the molded body was heat-treated (1,500 ° C. in an air atmosphere) with an electric furnace “Superburn” (trade name) manufactured by Motoyama, and a three-layer laminate having a thickness of about 6 mm was obtained.
The obtained three-layer laminate was subjected to the same evaluation as in Experimental Example 1. The result is shown in FIG. A quantitative change in Ta atoms was observed at the interface between the upper two layers, indicating a stable layer structure.

Experimental example 3
The α-alumina powder “TM-DAR” (trade name) (1.1 gram) was filled in a molding die having an inner diameter of 15 mm, and lightly compressed using a piston to form a disk. Thereafter, 2.6 g of YTaO ₄ -doped zirconia powder was evenly filled on the surface of the α-alumina layer in a molding die and lightly compacted. Next, in the molding die, the surface of this YTaO ₄ -doped zirconia layer was evenly filled with 1.5 g of TaZr _2.75 O ₈ powder and lightly compacted. Then, in the molding die, the Y _1.08 Ta _2.76 Zr _0.24 O ₉ powder and the TaZr _2.75 O ₈ powder were made equal in volume on the surface of the TaZr _2.75 O ₈ layer. The mixed powder 1.6g was filled and lightly compressed. Next, the laminate was press-molded at a pressure of 800 kg / cm ² and further CIP-molded at a hydrostatic pressure of 2.5 t / cm ² . Thereafter, the molded body was heat-treated (in the atmosphere, 1,500 ° C.) with an electric furnace “Superburn” (trade name) manufactured by Motoyama, and a four-layer laminate having a thickness of about 8 mm was obtained.
The obtained four-layer laminate was subjected to the same evaluation as in Experimental Example 1. The result is shown in FIG. A quantitative change in Ta atoms was observed at the interface between the upper two layers, indicating a stable layer structure.

  According to the heat-shielding structure of the present invention, the surface of the aluminum oxide layer is provided with a coating having low thermal conductivity and durability, so that it is a combustor in an aircraft jet engine, a high-temperature component in a power generation gas turbine, and other various plants. It is suitable for application to high-temperature parts and the like.

  10: heat shielding structure, 11: heat-resistant metal substrate, 13: aluminum oxide layer, 15: first layer, 17: second layer, 19: third layer

Claims (3)

A refractory metal substrate, a heat-resistant metal substrate of aluminum oxide layer formed on the surface of a first layer comprising a YTaO ₄ doped zirconia formed on the surface of the aluminum oxide layer, on the surface of the first layer And a formed second layer containing a compound (B) represented by the following general formula (11) .
Ta _1-4x Zr _{2.75 + 5x} O ₈ (11)
(Wherein x is -0.021 to 0.069) Furthermore, on the surface of the second layer, the compound (B) and the compound (C) represented by the following general formula (21) are each 30 to 30% when the total of both is 100% by volume. heat insulating structure of claim 1, further comprising a third layer in a proportion of 70 vol% and 30 to 70 vol%.
Y _{1 + y} Ta _3-3y Zr _3y O ₉ (21)
(In the formula, y is 0.05 to 0.10.) 3. The heat shield structure according to claim 1, wherein the refractory metal substrate is MCrAlY (M is at least one atom selected from Ni, Co, and Fe).