Solid-phase sintering preparation method of lanthanum-samarium-niobium-based high-temperature-sintering-resistant high-entropy thermal barrier coating

Abstract

The invention relates to the technical field of thermal barrier coating materials, in particular to a solid-phase sintering preparation method of a lanthanum-samarium-niobium-based high-temperature-sintering-resistant high-entropy thermal barrier coating, which comprises the following steps: chemical element substitution is carried out on an A site of an A2B2O7 type oxide, the high-entropy thermal barrier coating material is (La0. 2Sm0. 2Nb0. 2A0. 2B0. 2) 2Zr2O7, and A and B are different rare earth elements except La, Sm and Nb. High-entropy design is adopted, so that the thermal barrier coating material can stabilize the phase structure of the material at a high temperature, segregation is not prone to being generated, the anti-sintering performance of the material is remarkably improved, the application requirement of an aero-engine at the temperature of 1,300 DEG C or above is met, the high-entropy thermal barrier coating does not generate phase change after long-term heat treatment at the high temperature, and the thermal barrier coating material has the good thermal barrier performance. High phase stability is maintained, and the service life of the coating can be prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of thermal barrier coating materials, and in particular to a solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating that is resistant to high-temperature sintering. Background Art

[0002] Thermal barrier coatings (TBCs) are a kind of protective ceramic material coated on turbine blades. This material has the characteristics of low thermal conductivity, high melting point, high temperature phase structure and stable chemistry. It is the core technology of aircraft engine manufacturing.

[0003] Yttria partially stabilized zirconia (6%~8% YSZ) coating is currently the most widely used thermal barrier coating material. YSZ coating has the advantages of good thermal cycling, high melting point, low thermal conductivity, etc. However, when YSZ is above 1200℃, YSZ coating is prone to problems such as tetragonal phase to monoclinic phase transformation and sintering, which lead to coating shedding and failure. It cannot meet the engineering application requirements of the new generation of aircraft engines at temperatures of 1300℃ and above, and fails to solve the problem of premature peeling and failure of YSZ-based thermal barrier coatings during thermal cycling.

[0004] On the other hand, although A2B2O7 oxides have excellent properties such as high melting point, low thermal conductivity, low oxygen permeability, sintering resistance and radiation resistance, they are important candidate materials for thermal barrier coatings and nuclear waste treatment. However, A2B2O7 oxide ceramics have low thermal expansion coefficient, fracture toughness and thermal cycle life, which seriously limits their practical application in the field of thermal barrier coatings. Summary of the invention

[0005] The purpose of the present invention is to provide a solid phase sintering preparation method for a lanthanum-samarium-niobium based high-entropy thermal barrier coating resistant to high temperature sintering, so as to solve:

[0006] 1. The problem that yttria partially stabilized zirconia is difficult to meet the application requirements of the new generation of aircraft engines at temperatures of 1300°C and above;

[0007] 2. The low thermal expansion coefficient, fracture toughness and thermal cycle life of A2B2O7 type oxides greatly limit their widespread application in the field of thermal barrier coatings.

[0008] To achieve the above object, the present invention provides the following technical solution: a lanthanum-samarium-niobium-based high-entropy thermal barrier coating resistant to high-temperature sintering, comprising chemical element substitution at the A site of an A2B2O7-type oxide, wherein the high-entropy thermal barrier coating material is (La 0.2 Sm 0.2 Nb 0.2 A 0.2 B 0.2)2Zr2O7, wherein A and B are different rare earth elements other than La, Sm and Nb.

[0009] Preferably, A and B include but are not limited to Eu, Gd, Y and Yb.

[0010] The present invention also provides a solid phase sintering preparation method of a lanthanum-samarium-niobium based high-entropy thermal barrier coating resistant to high temperature sintering, comprising the following steps:

[0011] S1. Material preparation: prepare raw materials La2O3, Sm2O3, Nb2O3, A2O3, B2O3 and ZrO2, and the purity of each raw material is ≥99%;

[0012] S2, mixing ratio: weigh and mix the raw materials La2O3, Sm2O3, Nb2O3, A2O3, B2O3 and ZrO2 prepared in step S1 according to the molar ratio;

[0013] S3, first ball milling: the raw materials prepared in step S2 are placed in a polyurethane ball milling tank, and anhydrous ethanol is added, and then the mixture is placed in a planetary ball mill for the first ball milling to obtain a uniform powder;

[0014] S4, powder drying: drying the powder mixed in step S3 in an oven;

[0015] S5, secondary ball milling: pre-sintering the powder dried in step S4, crushing and sieving the pre-sintered powder, and then putting it into a polyurethane ball mill, adding anhydrous ethanol, and then performing secondary ball milling on the powder in the polyurethane ball mill by a planetary ball mill, and then putting the secondary ball milled powder into an oven for drying, and then crushing and sieving to obtain a uniform and fine high entropy powder;

[0016] S6. Obtaining bulk high-entropy ceramics: drying the high-entropy powder obtained in step S5, and then pressing the powder into tablets on a tablet press to obtain bulk high-entropy ceramics, and then placing the powder in a high-temperature box furnace for high-temperature sintering to finally obtain a lanthanum-gadolinium-samarium-based high-entropy thermal barrier coating.

[0017] Preferably, the grinding bodies in the planetary ball mill in step S3 are zirconium oxide balls, and the ball-to-powder ratio is 10:1.

[0018] Preferably, the mass ratio of powder to anhydrous ethanol in step S3 and step S5 is 1:1.5, the rotation speed of the planetary ball mill in step S3 is 350-450 r / min, and the ball milling is performed for 8-12 h, and the rotation speed of the planetary ball mill in step S5 is 400-550 r / min, and the ball milling is performed for 8-14 h.

[0019] Preferably, in step S4, the oven temperature is 80° C. and the drying time is 12 h.

[0020] Preferably, in step S5, the pre-sintering temperature is 1350° C. to 1450° C., and the holding time is 2 to 4 hours.

[0021] Preferably, in step S6, the tablet press pressure is 15-25 MPa, the holding time is 5-15 min, and the sintering temperature in step S6 is 1550° C.-1650° C., the sintering time is 4 h, and the sintering holding time is 2-6 h.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention adopts a high entropy design, so that the thermal barrier coating material of the present invention can stabilize the phase structure of the material at high temperature, is not easy to produce segregation, significantly improves the material's anti-sintering performance, and meets the application requirements of aircraft engines at temperatures of 1300°C and above. The high entropy thermal barrier coating will not undergo phase change after long-term heat treatment at high temperature, and maintains a high phase stability, which helps to extend the service life of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention provides a solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 (a) Surface morphology SEM of 2Zr2O7 high entropy ceramic block Figure 1 ;

[0025] Figure 2 The present invention provides a solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 (a) Surface morphology SEM of 2Zr2O7 high entropy ceramic block Figure 2 ;

[0026] Figure 3 This is the EDS mapping diagram corresponding to the Zr element in the solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering of the present invention;

[0027] Figure 4 This is an EDS mapping diagram corresponding to the Nb element in a solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to the present invention;

[0028] Figure 5 This is the EDS mapping diagram corresponding to the Y element of the solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering of the present invention;

[0029] Figure 6 This is the EDS mapping diagram corresponding to the Eu element in the solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering of the present invention;

[0030] Figure 7 This is the EDS mapping diagram corresponding to the Sm element in the solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering of the present invention;

[0031] Figure 8 This is the EDS mapping diagram corresponding to the La element in the solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to the present invention;

[0032] Fig. 9 The present invention provides a solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 )EDS spectrum of 2Zr2O7 high entropy oxide sample;

[0033] Fig.10 The present invention provides a solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 ) XRD patterns of 2Zr2O7 high entropy oxide bulk samples and single component samples;

[0034] Fig.11 The present invention provides a solid phase sintering preparation method of a lanthanum, samarium, and niobium based high-entropy thermal barrier coating resistant to high temperature sintering (La 0.2 Sm 0.2 Nb 0.2 G 0.2 Yb 0.2 )XRD patterns of 2Zr2O7 high entropy oxide bulk sample and single component sample. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Embodiment 1

[0037] See also Figures 1 to 9The present invention provides a technical solution: a lanthanum-samarium-niobium-based high-entropy thermal barrier coating resistant to high-temperature sintering, comprising chemical element substitution on the A site of the A2B2O7 type oxide, wherein the high-entropy thermal barrier coating material is (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 )2Zr2O7.

[0038] The present invention also provides a solid phase sintering preparation method of a lanthanum-samarium-niobium based high-entropy thermal barrier coating resistant to high temperature sintering, comprising the following steps:

[0039] S1. Material preparation: prepare raw materials La2O3, Sm2O3, Nb2O3, Eu2O3, Y2O3 and ZrO2, and the purity of each raw material is ≥99%;

[0040] S2, mixing ratio: 14.38g La2O3, 15.39g Sm2O3, 11.73g Nb2O3, 9.97g Y2O3, 15.54g Eu2O3 and 54.39g ZrO 2， The powders were weighed and mixed using an analytical balance, and the error of each powder was no more than 0.02g.

[0041] S3, first ball milling: In order to prevent the mixed powder from getting damp due to absorbing moisture in the air, the raw materials after the proportioning in step S2 are quickly placed in a polyurethane ball mill, zirconium oxide balls are used as grinding bodies, and the ball-to-powder ratio is 10:1, and anhydrous ethanol is used as a medium to stir evenly, wherein the mass ratio of powder to anhydrous ethanol is 1:1.5, and the mixture is placed in a planetary ball mill after the lid is tightly sealed, and the bolts for fixing the position are tightened, and the speed of the planetary ball mill is set to 350-450r / min, and the ball mill is milled for 8-12h, and the first ball milling is performed to obtain a uniform powder;

[0042] S4, powder drying: after taking out the ball mill from the ball mill in step S3, heat-treating the mixed powder, opening the cover of the ball mill, placing the entire ball mill in an oven, and keeping it warm at 80° C. for 12 hours to remove the adsorbed moisture;

[0043] S5, secondary ball milling: crush the block material dried in step S4 into powder with a medicine spoon, pour it into a 100-mesh sieve, press the fine particles through the sieve with a medicine spoon to obtain fine ceramic powder, put the ceramic powder into an Al2O3 crucible, mark it, put it into a high-temperature box furnace for pre-sintering, sinter it at 1350℃~1450℃ for 4h, and then keep it warm for 2~4h, finally sinter it into blocks, wait until the block powder cools down, and then put it into a polyurethane ball mill with zirconium oxide balls as The grinding body is subjected to secondary ball milling, and anhydrous ethanol with a ball-to-powder ratio of 10:1 is poured into the grinding body, wherein the ball milling step is consistent with the ball milling step in step S3, the rotation speed of the planetary ball mill is 400-550r / min, and the ball milling is performed for 8-14h, and then the ball mill is placed in a drying oven and kept at 80°C for 12h to remove moisture, and finally the dried block material is crushed into powder with a medicine spoon, poured into a 200-mesh sieve, and the particles are crushed with a medicine spoon, pressed through a sieve, and the desired uniform and fine high entropy powder is obtained;

[0044] S6. Obtaining block-shaped high-entropy ceramics: Take out an appropriate amount of the high-entropy powder obtained in step S5 and place it in a circular mold. Press it tightly and use a tablet press to press it into a circular sheet at 15-25 MPa. The pressure is maintained for 5-15 minutes. Five discs are pressed out of the powder for subsequent performance testing. Finally, all the discs and a small amount of powder are placed in a high-temperature box furnace, marked and classified, and sintered at 1550°C-1650°C for 4 hours. The heat is maintained for 2-6 hours, and the sheet-shaped and granular high-entropy ceramics are obtained after cooling.

[0045] Figure 1 and 2 for (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 (a) Surface morphology SEM image of 2Zr2O7 high entropy ceramic block, Figure 3 is the EDS mapping corresponding to the Zr element, Figure 4 is the EDS mapping corresponding to the Nb element, Figure 5 is the EDS mapping corresponding to the Y element, Figure 6 is the EDS mapping corresponding to the Eu element, Figure 7 is the EDS mapping corresponding to the Sm element, Figure 8 This is the EDS mapping corresponding to the La element. The average grain size is about 3 microns, and the grain boundaries are clear. In addition, there are a small number of pores in the SEM image. The EDS mapping shows Figure 1 As shown, all constituent elements are spatially uniform with no element enrichment.

[0046] in Fig. 9 for (La 0.2 Sm 0.2 Nb 0.2 Eu0.2 Y 0.2 )2Zr2O7 high entropy oxide sample EDS spectrum, the elemental composition and molar ratio of different elements high entropy (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 The chemistry and stoichiometry of the 2Zr2O7 sample are consistent with its own, indicating that no element loss occurs during the powder preparation and high-temperature sintering process.

[0047] Embodiment 2

[0048] Different from the first embodiment, the high entropy thermal barrier coating material is (La 0.2 Sm 0.2 Nb 0.2 G 0.2 Yb 0.2 )2Zr2O7;

[0049] S1. Material preparation: prepare raw materials La2O3, Sm2O3, Nb2O3, Gd2O3, Yb2O3 and ZrO2, and the purity of each raw material is ≥99%;

[0050] S2, mixing ratio: 13.5g La2O3 with purity ≥99%, 11.01gg Sm2O3, 14.44g Nb2O3, 15.01g Yb2O3, 16.32g Gd2O3 and 51.04g ZrO 2， The powders were weighed and mixed separately using an analytical balance, and the error of each powder was no more than 0.02g.

[0051] in Fig.10 for (La 0.2 Sm 0.2 Nb 0.2 Eu 0.2 Y 0.2 )XRD patterns of 2Zr2O7 high entropy oxide bulk sample and single component sample, and Fig.11 for (La 0.2 Sm 0.2 Nb 0.2 G 0.2 Yb 0.2 ) XRD patterns of 2Zr2O7 high entropy oxide bulk samples and single component samples;

[0052] Depend on Fig.10 and Fig.11 It can be seen that the high entropy oxide sample of the present invention is different from the standard XRD of a single component. Figure 1It shows that for deep exploration of structure formation, all corresponding peaks of the high entropy oxide material synthesized in the present invention deviate seriously from the higher angle region compared with the single component, which indicates that the size difference of the five rare earth ions leads to serious lattice distortion, especially with the increase of 2θ, the peak shift increases. The occurrence of this peak displacement is largely due to the shrinkage of cells in the lattice structure. Lattice distortion means that the crystal structure of the material is no longer perfect. In the present invention, this distortion enhances the overall structural stability of the material to a certain extent, because the occupation of rare earth ions of different sizes in the lattice will lead to changes in lattice parameters. This change will make the lattice structure more complex and stable, thereby resisting phase change and sintering at high temperatures.

[0053] The distortion caused by the size difference of different rare earth ions in the lattice not only enhances the structural stability of the material, making it more resistant to phase change and sintering at high temperatures, but also improves the phase stability, ensuring that the material maintains the stability of structure and performance in a high temperature environment. In addition, lattice distortion may optimize the thermal properties of the material by increasing phonon scattering, reducing thermal conductivity, reducing heat transfer, and improving thermal efficiency. At the same time, this distortion also enhances the high-temperature mechanical properties of the material, allowing it to maintain excellent performance under extreme conditions. In summary, lattice distortion is one of the key factors in improving the performance of the material of the present invention.

[0054] The present invention adopts a high entropy design, so that the thermal barrier coating material of the present invention can stabilize the phase structure of the material at high temperature, is not easy to produce segregation, significantly improves the material's anti-sintering performance, and meets the application requirements of aircraft engines at temperatures of 1300°C and above. The high entropy thermal barrier coating will not undergo phase change after long-term heat treatment at high temperature, and maintains a very high phase stability, which helps to extend the service life of the coating.

[0055] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A lanthanum, samarium, niobium-based high-entropy thermal barrier coating resistant to high-temperature sintering, characterized in that: The high entropy thermal barrier coating material comprises (La 0.2 Sm 0.2 Nb 0.2 A 0.2 B 0.2 )2Zr2O7, wherein A and B are different rare earth elements other than La, Sm and Nb.

2. The solid phase sintering preparation method of a lanthanum, samarium, niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to claim 1, characterized in that: The A and B include but are not limited to Eu, Gd, Y and Yb.

3. A solid phase sintering preparation method of the lanthanum, samarium, niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to claim 1, characterized in that: The following steps are involved: S1. Material preparation: prepare raw materials La2O3, Sm2O3, Nb2O3, A2O3, B2O3 and ZrO2, and the purity of each raw material is ≥99%; S2, mixing ratio: weigh and mix the raw materials La2O3, Sm2O3, Nb2O3, A2O3, B2O3 and ZrO2 prepared in step S1 according to the molar ratio; S3, first ball milling: the raw materials prepared in step S2 are placed in a polyurethane ball milling tank, and anhydrous ethanol is added, and then the mixture is placed in a planetary ball mill for the first ball milling to obtain a uniform powder; S4, powder drying: drying the powder mixed in step S3 in an oven; S5, secondary ball milling: pre-sintering the powder dried in step S4, crushing and sieving the pre-sintered powder, and then putting it into a polyurethane ball mill, adding anhydrous ethanol, and then performing secondary ball milling on the powder in the polyurethane ball mill by a planetary ball mill, and then putting the secondary ball milled powder into an oven for drying, and then crushing and sieving to obtain a uniform and fine high entropy powder; S6. Obtaining bulk high-entropy ceramics: drying the high-entropy powder obtained in step S5, and then pressing the powder into tablets on a tablet press to obtain bulk high-entropy ceramics, and then placing the powder in a high-temperature box furnace for high-temperature sintering to finally obtain a lanthanum-gadolinium-samarium-based high-entropy thermal barrier coating.

4. The solid phase sintering preparation method of a lanthanum-samarium-niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to claim 3 is characterized in that: The grinding bodies in the planetary ball mill in step S3 are zirconium oxide balls, and the ball-to-powder ratio is 10:

1.

5. The solid phase sintering preparation method of a lanthanum, samarium, niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to claim 3, characterized in that: The mass ratio of powder to anhydrous ethanol in step S3 and step S5 is 1:1.5, the rotation speed of the planetary ball mill in step S3 is 350-450 r / min, and the ball milling is 8-12 h, and the rotation speed of the planetary ball mill in step S5 is 400-550 r / min, and the ball milling is 8-14 h.

6. The solid phase sintering preparation method of a lanthanum, samarium, niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to claim 3, characterized in that: In the steps S4 and S5, the oven temperature is 80° C. and the drying time is 12 hours.

7. The solid phase sintering preparation method of a lanthanum, samarium, niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to claim 3, characterized in that: In the step S5, the pre-sintering temperature is 1350° C. to 1450° C., the sintering time is 4 hours, and the holding time is 2 to 4 hours.

8. The solid phase sintering preparation method of a lanthanum, samarium, niobium based high-entropy thermal barrier coating resistant to high temperature sintering according to claim 3, characterized in that: In the step S6, the tablet press pressure is 15-25 MPa, the pressure holding time is 5-15 min, and the sintering temperature in the step S6 is 1550° C.-1650° C., the sintering time is 4 h, and the sintering holding time is 2-6 h.

Images