Hafnium oxide-lanthanum hafnate-based low-thermal-expansion low-thermal-conductivity composite thermal barrier / environmental barrier coating material and preparation method thereof, thermal barrier / environmental barrier coating and engine

Abstract

The invention belongs to the technical field of thermal protection coating materials, and discloses a hafnium oxide-lanthanum hafnate-based low-thermal-expansion low-thermal-conductivity composite thermal barrier / environmental barrier coating material and a preparation method thereof, a thermal barrier / environmental barrier coating and an engine. The hafnium oxide-lanthanum hafnate-based low-thermal-expansion low-thermal-conductivity composite thermal barrier / environmental barrier coating material comprises x vol% of HfO2 (1-x) vol% of La2Hf2O7, and x is larger than 0 and smaller than 100. The hafnium oxide-lanthanum hafnate-based low-thermal-expansion low-thermal-conductivity composite thermal barrier / environmental barrier coating material provided by the invention can improve the use temperature of a substrate, and has the advantages of high melting point, low thermal expansion coefficient and low thermal conductivity.

Description

Technical Field

[0001] This invention belongs to the technical field of thermal protective coating materials, specifically relating to a hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material with low thermal expansion and low thermal conductivity, its preparation method, thermal barrier / environmental barrier coating, and engine. Background Technology

[0002] With the increasing service temperatures of aero-engines, ceramic matrix composites (CMCs) have become important substrate materials for hot-end components. CMCs possess advantages such as low density, higher temperature resistance, and superior high-temperature mechanical properties, which can significantly increase the turbine inlet gas temperature, improve gas efficiency and thrust-to-weight ratio, making them an important development direction for future aero-engines. The mainstream CMC is silicon carbide-silicon carbide microceramic matrix material (SiC / SiC). f -CMCs), during the service of aero engines, the high-temperature combustion gases containing water vapor cause SiC to undergo an oxidation reaction to generate SiO2. The surface SiO2 further reacts with water vapor to generate Si(OH)4, which escapes, resulting in SiC / SiC... f -CMCs components are corroded and damaged. Therefore, SiC / SiC f - A coating resistant to high-temperature water vapor corrosion, i.e., a thermal barrier / environmental barrier coating, needs to be prepared on the surface of CMCs to ensure that the CMC materials are not directly exposed to high-temperature water vapor / oxygen environments and are protected from the corrosive effects of high-temperature water vapor. Typical thermal barrier / environmental barrier coating materials are rare earth silicate ceramic materials, which are widely studied and applied due to their excellent thermal properties and resistance to water vapor corrosion.

[0003] Rare earth silicate ceramics have low melting points and are prone to failure when operating at higher temperatures, such as 1500℃. With the further increase in turbine inlet temperature, in order to meet the requirements of 1500℃~1600℃... o The application requirements of SiC-CMCs in C environment require that the outer coating protect against both water vapor corrosion and high temperature erosion. The performance of a single material is difficult to meet these requirements simultaneously. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one objective of this invention is to provide a hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material with low thermal expansion and low thermal conductivity, its preparation method, a thermal barrier / environmental barrier coating, and an engine. The hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material provided by this invention can improve the operating temperature of the substrate and also has advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0005] In a first aspect, the present invention provides a hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material with low thermal expansion and low thermal conductivity, the hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material comprising: x vol% HfO2• (1-x)vol% La2Hf2O7, wherein 0 < x < 100.

[0006] The hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material according to the above embodiments of the present invention is based on HfO2 and La2Hf2O7. By adjusting the relative volume fractions of HfO2 and La2Hf2O7, the composite hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material simultaneously possesses a monoclinic phase and a cubic phase. A reasonable HfO2 ratio results in a low coefficient of thermal expansion for the composite material, and a reasonable La2Hf2O7 ratio results in a low thermal conductivity for the composite material. The two-phase material refines the grains and gives the material a good microstructure, which can improve the operating temperature of the substrate. It also has advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0007] In addition, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material according to the above embodiments of the present invention may also have the following additional technical features: In some embodiments of the present invention, x = 25~75. Therefore, this hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0008] In some embodiments of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material comprises a monoclinic phase structure HfO2. Therefore, this hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0009] In some embodiments of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material comprises a cubic phase structure La2Hf2O7. Therefore, this hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0010] In some embodiments of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has a coefficient of thermal expansion α ≤ 8.8 × 10⁻⁶ at 1300 °C. -6 / K. Therefore, this hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has advantages such as high melting point, low coefficient of thermal expansion and low thermal conductivity.

[0011] In some embodiments of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has a thermal conductivity κ ≤ 2.5 W·m at 1200℃. -1 ·K -1 Therefore, this hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material with low thermal expansion and low thermal conductivity has advantages such as high melting point, low coefficient of thermal expansion and low thermal conductivity.

[0012] In a second aspect of the present invention, a method for preparing the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material as described in the first aspect is proposed, comprising: mixing HfO2 and La2Hf2O7 in a volume ratio to obtain a precursor mixture; ball milling the precursor mixture with a solvent to obtain a mixed slurry; performing solid-liquid separation on the mixed slurry to obtain a block material; sieving the block material and pre-pressing it; and calcining it at 1450℃-1700℃ for 5h-10h to obtain the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material.

[0013] Therefore, the preparation method of hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material proposed in this invention produces a structurally stable hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material with excellent thermodynamic properties.

[0014] In a third aspect, the present invention provides a thermal barrier / environmental barrier coating comprising the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material described in the first aspect of this application. Thus, this thermal barrier / environmental barrier coating simultaneously possesses the advantages of high melting point, low coefficient of thermal expansion, low thermal conductivity, and high fracture toughness, and can be matched with ceramic matrix composite substrates with low coefficients of thermal expansion.

[0015] In a fourth aspect, the present invention provides an engine comprising the thermal barrier / environmental barrier coating described in the third aspect of the invention. Consequently, the engine has a longer service life.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 The XRD patterns of the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating materials prepared in Examples 1-2 of the present invention are shown.

[0018] Figure 2 Backscattered SEM images of the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating materials prepared in Examples 1-2 of the present invention are shown. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] In a first aspect, the present invention proposes a hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material comprising: x vol% HfO2• (1-x)vol% La2Hf2O7, wherein 0 < x < 100.

[0021] As an example, the value of x can be 0.1, 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 99, or any value between the two. According to other embodiments of the invention, x = 25 to 75.

[0022] The hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material according to the above embodiments of the present invention is based on HfO2 and La2Hf2O7. By adjusting the relative volume fractions of HfO2 and La2Hf2O7, the composite hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material simultaneously possesses both monoclinic and cubic phases. A reasonable HfO2 ratio results in a low coefficient of thermal expansion for the composite material, and a reasonable La2Hf2O7 ratio results in a low thermal conductivity for the composite material. The two-phase material refines the grains and gives the material a good microstructure, which can improve the operating temperature of the substrate. Thus, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material simultaneously possesses advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0023] It can be understood that x refers to the volume percentage of HfO2 in the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material.

[0024] According to an embodiment of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has a coefficient of thermal expansion α ≤ 8.8 × 10⁻⁶ at 1300 °C. -6 / K, for example, could be 8.8 × 10 -6 / K, 8×10 -6 / K, 7×10 -6 / K, 6×10 -6 / K, 5×10 -6 / K, 4×10 -6 / K, 3×10 -6 / K, 2×10 -6 / K, 1×10 -6 / K, 10 -7 The coefficient of thermal expansion of the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material at 1300℃ is controlled within the above range, or any numerical range between / K and the two. This hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has a low coefficient of thermal expansion, which can be well matched with the ceramic matrix composite substrate and effectively protect the ceramic matrix composite substrate.

[0025] The coefficient of thermal expansion α of hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating materials at 1300℃ can be determined by the following method: According to the national standard GB / T 16535-2008-Test Method for Linear Thermal Expansion Coefficient of Fine Ceramics - Push Rod Method, the thermal expansion coefficient of the sample was tested using the push rod method, wherein the sample size was 25mm×5mm×5mm.

[0026] According to an embodiment of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material comprises a monoclinic phase structure HfO2. This refines the grains, giving the material a favorable microstructure, which can increase the operating temperature of the substrate. The hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material simultaneously possesses advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0027] According to an embodiment of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material comprises a cubic phase structure La2Hf2O7. This refines the grains, giving the material a favorable microstructure, which can increase the operating temperature of the substrate. The hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material simultaneously possesses advantages such as high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0028] According to an embodiment of the present invention, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material has a thermal conductivity κ ≤ 2.5 W·m at 1200℃. -1 ·K -1 As an example, the thermal conductivity κ of a hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material at 1200℃ can be 2.5 W·m. -1 ·K -1 2.2 W·m -1 ·K-1 2W·m -1 ·K -1 1.5 W·m -1 ·K -1 1W·m -1 ·K -1 0.8 W·m -1 ·K -1 0.5 W·m -1 ·K -1 Or any value range between the two. This can further reduce the damage to the substrate caused by high temperatures and extend its lifespan.

[0029] In a second aspect, the present invention provides a method for preparing the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material as described in the first aspect, the method comprising: S1. Mix HfO2 and La2Hf2O7 in a volume ratio to obtain a precursor mixture.

[0030] According to some embodiments of the present invention, before the step of mixing the raw material components to obtain the precursor mixture, the raw material components may be calcined to remove impurities such as water and carbon dioxide adsorbed by the raw material components. For example, the raw material components are calcined at 1100°C for 1-3 hours. The calcination time can be 1 hour, 2 hours, 3 hours, or any value range between the two.

[0031] S2. The precursor mixture and solvent are ball-milled to obtain a mixed slurry.

[0032] According to some embodiments of the present invention, ball milling can be performed using zirconia balls and a precursor mixture. Exemplarily, the mass ratio of the precursor mixture to the zirconia balls is between 1:10 and 1:20, and the ball milling speed is between 200 rpm and 300 rpm. The solvent can be alcohol or deionized water. As an example, the mass ratio can be 1:10, 1:12, 1:15, 1:18, 1:20, or any value range between the two; the ball milling speed can be 200 rpm, 250 rpm, 300 rpm, or any value range between the two.

[0033] S3. After solid-liquid separation of the mixed slurry, block material is obtained. After sieving the block material, it is pre-pressed and then calcined at 1450℃-1700℃ for 5h-10h to obtain hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material.

[0034] As an example, the calcination temperature can be 1450℃, 1500℃, 1550℃, 1600℃, 1700℃ or any range between the two, and the calcination time can be 5h, 6h, 7h, 8h, 9h, 10h or any range between the two.

[0035] High-density thermal barrier-environmental barrier ceramic coating materials can be obtained by calcining at 1450℃-1700℃ for 5-10 hours. These materials can be used as EB-PVD targets (electron beam physical vapor deposition targets) or as high-temperature structural materials.

[0036] According to some embodiments of the present invention, the step of pre-compressing the obtained block material includes: sieving the ball-milled powder, granulating it by spraying, and calcining it at 1350-1500℃ for 1-3 hours (for example, the calcination temperature can be 1350℃, 1400℃, 1450℃, 1500℃ or any range between two), followed by sieving to select particles with a size of 30-110 micrometers (the size can be 30 micrometers, 50 micrometers, 70 micrometers, 90 micrometers, 100 micrometers, 110 micrometers or any range between two), at which point the 30-110 micrometer particles can be used for atmospheric plasma spraying. The pre-compressing can be performed using cold isostatic pressing.

[0037] In summary, the method for preparing hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating materials proposed in this invention uses hafnium oxide-lanthanum hafnium oxide composite materials with excellent thermodynamic properties and high melting points as the target material. By controlling the relative volume fraction of hafnium oxide and lanthanum hafnium oxide, the target material is ensured to have both monoclinic and cubic phases, and the target material is synthesized through a simple solid-state reaction.

[0038] In a third aspect, the present invention provides a thermal barrier / environmental barrier coating comprising the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material described in the first aspect of this application. Thus, this thermal barrier / environmental barrier coating simultaneously possesses the advantages of high melting point, low coefficient of thermal expansion, low thermal conductivity, and high fracture toughness, and can be matched with ceramic matrix composite substrates with low coefficients of thermal expansion.

[0039] According to some embodiments of the present invention, this application provides a thermal barrier / environmental barrier coating, which is formed by granulation and deposition of the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material of the first aspect of the present application.

[0040] Hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coatings with low thermal expansion and low thermal conductivity can be deposited using several techniques. Deposition methods include, but are not limited to, thermal spraying (plasma spraying, flame spraying, and HVOF spraying), sputtering, and electron beam physical vapor deposition (EBPVD).

[0041] In a fourth aspect, the present invention provides an engine comprising the thermal barrier / environmental barrier coating described in the third aspect. Thus, the thermal barrier / environmental barrier coating, applied to the ceramic matrix composite material of the engine, effectively protects the ceramic matrix composite material from corrosion and damage, thereby extending the engine's lifespan.

[0042] According to some embodiments of the present invention, the engine includes an aircraft engine.

[0043] The present disclosure will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0044] Example 1 (a) The raw material components are HfO2 and La2Hf2O7, which are calcined at 1100℃ for 2 hours to remove adsorbed water and carbon dioxide and other impurities; (b) Weigh the dried HfO2 and La2Hf2O7 in a specific ratio, and the contents are shown in Table 1; (c) The weighed powder is ball-milled and mixed, wherein the ball-milling media are zirconium oxide balls and alcohol, and the ball-milling time is 8 hours.

[0045] (d) Separate and dry the slurry after ball milling, and grind and sieve the obtained powder to obtain hafnium oxide-lanthanum hafnium oxide composite powder; (e) The powder after ball milling in step (d) is passed through a 250-mesh sieve, spray granulated, calcined at 1400℃ for 2 hours, and then sieved to select particles with a size of 30-110 micrometers, which can be used for atmospheric plasma spraying. (f) Using a 15mm diameter abrasive, the powder after ball milling in step (e) is pre-pressed into shape with a pressure of 7 kg; the obtained blank is held at 250 MPa for 90 seconds using cold isostatic pressing. (g) Finally, the sample is calcined at 1550 °C for 8 hours to obtain a high-density bulk sample, which can be used as an EB-PVD target material or as a high-temperature structural material.

[0046] Examples 2-7 The preparation process is the same as in Example 1, except that the ratio of HfO2 to La2Hf2O7 is different. The composition of the thermal barrier / environmental barrier ceramic materials in Examples 2-7 is shown in Table 1.

[0047] Comparative Example 1 The preparation process is the same as in Example 1, except that it is not a composite material and the rare earth ions are different. Gd2Hf2O7 raw material powder is used to obtain a typical high melting point and low thermal conductivity rare earth hafnium salt material, but with a high coefficient of thermal expansion. The composition of Comparative Example 1 is shown in Table 1.

[0048] Comparative Examples 2-3 The preparation process is the same as that of Comparative Example 1, except that only HfO2 or La2Hf2O7 is used, see Table 1.

[0049] Table 1

[0050] The XRD patterns of the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating materials prepared in Examples 1-2 are shown below. Figure 1 As shown, embodiments 1-2 of this application contain both a monoclinic phase structure HfO2 and a cubic phase structure La2Hf2O7.

[0051] Backscattered SEM images of the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating materials prepared in Examples 1-2 are shown below. Figure 2 As shown, embodiments 1-2 of this application contain both a monoclinic phase structure HfO2 and a cubic phase structure La2Hf2O7.

[0052] Testing and Analysis 1. GB / T 16535-2008- Test method for linear thermal expansion coefficient of fine ceramics - push rod method. The push rod method is used to test the thermal expansion coefficient of the sample. The sample size is 25mm×5mm×5mm. The test results are shown in Table 2.

[0053] 2. Determination of thermal conductivity: The thermal diffusivity was determined by laser flare method, the specific heat capacity was calculated by Nemann-Kopp theorem, and the sample density was measured by Archimedes method. The thermal conductivity was then calculated from the thermal diffusivity, heat capacity, and density.

[0054] Table 2

[0055] As can be seen from the results in Tables 1-2, the hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material prepared by the embodiments of the present invention has the advantages of high melting point, low coefficient of thermal expansion, and low thermal conductivity.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," "some implementations," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hafnium oxide - lanthanum oxyfluoride based low thermal expansion low thermal conductivity composite thermal and environmental barrier coating material characterized in that, The hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material comprises: x vol% HfO2•(1-x)vol% La2Hf2O7, where 0 < x < 100.

2. The hafnium oxide - lanthanum cerate based low thermal expansion, low thermal conductivity composite thermal and environmental barrier coating material according to claim 1, wherein, x=25~75。 3. The hafnium oxide - lanthanum cerate based low thermal expansion, low thermal conductivity composite thermal and environmental barrier coating material of claim 1, wherein, The hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material includes a monoclinic phase structure HfO2.

4. The hafnium oxide - lanthanum cerate based low thermal expansion, low thermal conductivity composite thermal and environmental barrier coating material of claim 1, wherein, The hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material comprises a cubic phase structure La2Hf2O7.

5. The hafnium oxide - lanthanum cerate based low thermal expansion, low thermal conductivity composite thermal and environmental barrier coating material of claim 1, wherein, The hafnium oxide - lanthanum oxyfluoride based low thermal expansion low thermal conductivity composite thermal and environmental barrier coating material has a thermal expansion coefficient a < 8.8 x 10 -6 / K at 1300 °C.

6. The hafnium oxide - lanthanum cerate based low thermal expansion, low thermal conductivity composite thermal and environmental barrier coating material of claim 1, wherein, The lanthanum fluoride - lanthanum oxyfluoride based low thermal expansion low thermal conductivity composite thermal and environmental barrier coating material has a thermal conductivity K < 2.5 W-m at 1200 °C -1 · K -1 .

7. A method of making the hafnium oxide-lanthanum cerate based low thermal expansion low thermal conductivity composite thermal and environmental barrier coating material of any one of claims 1-6, characterized in that, include: HfO2 and La2Hf2O7 were mixed in a certain volume ratio to obtain a precursor mixture; The precursor mixture was ball-milled with a solvent to obtain a mixed slurry; After solid-liquid separation of the mixed slurry, block material is obtained. The block material is sieved and pre-pressed, and then calcined at 1450℃-1700℃ for 5h-10h to obtain hafnium oxide-lanthanum hafnium oxide-based low thermal expansion and low thermal conductivity composite thermal barrier / environmental barrier coating material.

8. The method of claim 7, wherein, Before the step of mixing HfO2 and La2Hf2O7 in a volume ratio to obtain the precursor mixture, the following steps are also included: HfO2 and La2Hf2O7 were calcined at 1000℃-1200℃ for 1-3 hours.

9. A thermal / environmental barrier coating, characterized by, The thermal barrier / environmental barrier coating comprises the hafnium oxide-lanthanum hafnium oxide-based composite thermal barrier / environmental barrier coating material with low thermal expansion and low thermal conductivity as described in any one of claims 1-6.

10. An engine characterized by, The engine includes the thermal barrier / environmental barrier coating as described in claim 9.

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