High-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness and preparation method thereof

Abstract

The application discloses a high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness and a preparation method thereof, and belongs to the technical field of thermal barrier coatings. 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7. The high-entropy rare earth strontium aluminate thermal barrier coating material is synthesized by a solid phase method. According to the high-entropy design of the rare earth strontium aluminate, five different rare earth elements are doped in the rare earth position, the dislocation resistance of the ceramic is increased by using the serious lattice distortion effect, and the mechanical properties are improved. Through nanoindentation test, the fracture toughness reaches 2.15MPa.m 0.5 , so that the high-entropy rare earth strontium aluminate thermal barrier coating can better prevent the growth and extension of cracks.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of thermal barrier coatings, in particular to a high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness and a preparation method thereof. BACKGROUND

[0002] Thermal barrier coatings are applied to extreme temperature and oxidation corrosion environment, and its main role is to protect the aero-engine turbine blades from being used for a long time at high temperature. With the continuous increase of turbine inlet temperature in recent years, the traditional thermal barrier coating cannot meet the requirements of the existing engine, so it is urgent to study a new generation of thermal barrier coating. The requirement of thermal barrier coating is extremely harsh, which requires low thermal conductivity, high thermal expansion coefficient, high fracture toughness and hardness, low elastic modulus, and good corrosion resistance.

[0003] At present, among all ceramic materials, yttria-stabilized zirconia (YSZ) is the most widely used thermal barrier coating material, but it has the disadvantage of high temperature phase transition, so people have to find new materials to make up for its shortcomings. Researchers found that rare earth strontium aluminate has high thermal expansion performance and comparable thermal conductivity to YSZ, but its mechanical properties have not been studied. SUMMARY

[0004] The purpose of the present application is to provide a high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness and a preparation method thereof.

[0005] The high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness of the present application has a chemical composition formula of (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7.

[0006] A preparation method of the high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness as described above, according to the chemical formula, the La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powders are mixed and then wet ball-milled to obtain a mixed precursor, the mixed precursor is dried, preheated and calcined to obtain the high-entropy rare earth strontium aluminate thermal barrier coating material.

[0007] Further, the preheating temperature is 800-1200℃, and the time is 2-10h.

[0008] Further, the calcination temperature in the muffle furnace is 1350-1550℃, and the time is 2-100h.

[0009] Further, the sintering temperature of the discharge plasma calcination is 1350-1550 DEG C, and the time is at least 5 min.

[0010] Further, the drying temperature is 80 DEG C, and the time is 12-24 h.

[0011] Further, the purity of the La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powder is all greater than or equal to 99.9%.

[0012] Further, the Al2O3 is gamma type nano Al2O3.

[0013] Further, the liquid of the wet ball milling is ethanol or isopropyl alcohol.

[0014] Further, the mass ratio of the raw material powder to the large ball milling beads and the small ball milling beads is 1:1.5:1.5, the diameter of the large ball milling beads is 5 mm, the diameter of the small ball milling beads is 2 mm, the ball milling rotating speed is 450 rpm, and the time is 12 h.

[0015] The beneficial effects of the present application are as follows:

[0016] The present application is high-entropy design of rare earth strontium aluminate, five different rare earth elements are doped in the rare earth position, the dislocation resistance of the ceramic is increased by using the serious lattice distortion effect, and the mechanical properties are improved. 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 The fracture toughness of (La 0.5 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 synthesized by the solid phase synthesis method is 2.15 MPa·m , it has high thermal expansion performance, good high-temperature phase stability, good sintering resistance and high hardness, can resist the impact and erosion wear of external particles, so that the high-entropy rare earth strontium aluminate thermal barrier coating can better prevent the growth and extension of cracks, and has more excellent effect when coping with the damage of external force to the coating.

[0017] The high-entropy rare earth strontium aluminate salt thermal barrier coating material of the present application has simple synthesis process and low cost, and is an ideal thermal barrier coating material. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 of example 1, and the X-ray diffraction pattern is obtained by sintering at 1550 DEG C for 10 h.

[0019] Figure 2 is high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 sintered at 1550℃ for 50h to obtain an X-ray diffraction pattern;

[0020] Figure 3 is high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 sintered at 1550℃ for 50h to obtain an X-ray diffraction pattern;

[0021] Figure 4 is high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 sintered at 1550℃ for 50h to obtain an X-ray diffraction pattern;

[0022] Figure 5 is high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 sintered at 1550℃ for 50h to obtain an X-ray diffraction pattern; DETAILED DESCRIPTION

[0023] The present application will be described in detail below with some drawings and specific examples, but in no way limits the present application. The described examples do not include all the examples, and any changes or substitutions described based on the present application are within the scope of protection.

[0024] Example 1:

[0025] A method for preparing a high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness has the following steps:

[0026] (1) Calculate the amount of oxide according to the molar ratio of elements required to prepare high-entropy rare earth strontium aluminate ceramic, weigh the corresponding amount of La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powder, and add isopropanol as a ball milling medium to fully dissolve the mixed powder;

[0027] (2) Calculate the amount of ball milling beads according to the total amount of powder in step (1), and the mass ratio of large ball milling beads to small ball milling beads is 1:1.5:1.5 according to the powder mass ratio;

[0028] (3) Put the ball milling jar into the planetary ball mill and adjust the rotation speed to 450 rpm for 12 h, so as to obtain a mixed and uniform slurry. Dry the obtained mixed slurry in an oven at 80°C for 12 h, and then pretreat it in a muffle furnace at 950°C for 10 h;

[0029] (4) Grind the powder obtained in step (3), sieve it through a 200-mesh sieve, PVA granulate it, and then press it into a shape, and then sinter it in a muffle furnace at 1550°C for 10 h to obtain a pure-phase high-entropy rare earth strontium aluminate salt thermal barrier coating material.

[0030] Figure 1 is a high-entropy rare earth strontium aluminate salt (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 sintered at 1550°C for 10 h. It can be seen that a pure-phase high-entropy rare earth strontium aluminate salt thermal barrier coating material is obtained.

[0031] Example 2:

[0032] A high-entropy rare earth strontium aluminate salt thermal barrier coating material with high fracture toughness, which has a chemical composition of (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7. The material synthesis steps are as follows:

[0033] (1) Calculate the amount of oxides according to the molar ratio of elements required to prepare the high-entropy rare earth strontium aluminate salt ceramic, and weigh the corresponding amount of La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powders. Add isopropanol as a ball milling medium to make the mixed powder fully dissolved;

[0034] (2) Calculate the amount of ball milling beads according to the total amount of powder in step (1), and the mass ratio of large ball milling beads to small ball milling beads is 1:1.5:1.5 according to the powder mass ratio;

[0035] (3) Put the ball milling jar into the planetary ball mill and adjust the rotation speed to 450 rpm for 12 h, so as to obtain a mixed and uniform slurry. Dry the obtained mixed slurry in an oven at 80°C for 12 h, and then pretreat it in a muffle furnace at 950°C for 10 h;

[0036] (4) The powder obtained in step (3) is ground, sieved through a 200 mesh sieve, PVA granulated, and then compression molded, and then sintered in a muffle furnace at 1550°C for 50h to obtain a pure phase high-entropy rare earth strontium aluminate salt thermal barrier coating material.

[0037] Figure 2 is a high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 of Example 2 sintered at 1550°C for 50h to obtain an X-ray diffraction pattern; it can be seen that the present application obtains a pure phase high-entropy rare earth strontium aluminate salt thermal barrier coating material.

[0038] Example 3:

[0039] A high-entropy rare earth strontium aluminate salt thermal barrier coating material with high fracture toughness, the chemical composition of which is (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7. The material synthesis steps are as follows:

[0040] (1) Calculate the required content of each element according to the amount of high-entropy rare earth strontium aluminate salt required, weigh the corresponding amount of La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powder, and add isopropanol as a ball milling medium to make the mixed powder fully dissolved;

[0041] (2) Calculate the amount of ball milling beads required according to the total amount of powder weighed in step (1), and the mass ratio of large ball milling beads to small ball milling beads is 1:1.5:1.5;

[0042] (3) Put the ball milling jar into the planetary ball mill and adjust the speed to 450 rpm for 12h, thereby obtaining a uniformly mixed slurry, dry the obtained mixed slurry in an oven at 80°C for 12h, and then pretreat in a muffle furnace at 950°C for 10h;

[0043] (4) The powder obtained in step (3) is ground, sieved through a 200 mesh sieve, and then the obtained high-entropy rare earth strontium aluminate salt powder is sintered by spark plasma sintering at a heating rate of 100°C / min, 20MPa, and 1550°C for 5min, and then the surface is polished and tested for fracture toughness.

[0044] Figure 3 is a high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2Eu 0.2 Gd 0.2 )2SrAl2O7, the fracture toughness of the high-entropy rare earth strontium aluminate thermal barrier coating material is 2.15 MPa·m 0.5 , and the hardness is 14.47 GPa.

[0045] Example 4:

[0046] A preparation method of a high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness has the following steps:

[0047] (1) The amount of oxide is calculated according to the molar ratio of elements required to prepare the high-entropy rare earth strontium aluminate salt ceramic, the corresponding amount of La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powder is weighed, and the seven kinds of powder are poured into the ball mill jar in turn, and isopropanol is added as the ball milling medium to make the mixed powder fully dissolved;

[0048] (2) The amount of ball milling beads required is calculated according to the total amount of powder weighed in step (1), and the mass ratio of large ball milling beads to small ball milling beads is 1:1.5:1.5 according to the mass ratio of powder;

[0049] (3) The ball mill jar is placed in a planetary ball mill and adjusted to a rotation speed of 450 rpm for 12 hours, thereby obtaining a uniformly mixed slurry, and the obtained mixed slurry is dried in an oven at 80°C for 12 hours, and then pretreated in a muffle furnace at 1200°C for 5 hours;

[0050] (4) The powder obtained in step (3) is ground, sieved through a 200 mesh sieve, PVA granulated, and then pressed into shape, and then sintered in a muffle furnace at 1550°C for 10 hours to obtain a pure phase high-entropy rare earth strontium aluminate salt thermal barrier coating material.

[0051] The thermal expansion is measured by a high-temperature thermal dilatometer to be 12.48×10 -6 K -1 (room temperature-1500°C).

[0052] Example 5:

[0053] A preparation method of a high-entropy rare earth strontium aluminate thermal barrier coating material with high fracture toughness has the following steps:

[0054] (1) The amount of oxide is calculated according to the molar ratio of elements required to prepare the high-entropy rare earth strontium aluminate salt ceramic, the corresponding amount of La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powder is weighed, and the seven kinds of powder are poured into the ball mill jar in turn, and isopropanol is added as the ball milling medium to make the mixed powder fully dissolved;

[0055] (2) according to the total amount of powder called in step (1) to calculate the required amount of ball mill beads, according to the powder mass ratio, the mass ratio of large ball mill beads to small ball mill beads is equal to 1:1.5:1.5;

[0056] (3) Put the ball mill jar into the planetary ball mill and adjust the rotation speed to 450 rpm for 12 h, so as to obtain a uniformly mixed slurry. Dry the obtained mixed slurry in an oven at 80℃ for 24 h, and then pretreat in a muffle furnace at 1200℃ for 4 h;

[0057] (4) Grind the powder obtained in step (3), pass through a 200 mesh sieve, PVA granulation, and then press into shape. Sinter at 1550℃ in a muffle furnace for 50 h to obtain a high-entropy rare earth strontium aluminate salt thermal barrier coating material.

[0058] Then observe the micro-morphology by scanning electron microscopy.

[0059] Figure 4 is the high-entropy rare earth strontium aluminate salt (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7 in Example 5 at 1550℃ for 10 h and 50 h.

[0060] As can be seen from the figure, the grain growth rate is slow from 10 h to 50 h, so the high-entropy rare earth strontium aluminate salt prepared in the present application has good high-temperature phase stability.

[0061] Comparative Example 1:

[0062] According to the rare earth aluminate of the formula Gd2SrAl2O7, the synthesis steps are as follows: calculate the amount of oxide according to the molar ratio of elements required to prepare the strontium gadolinium aluminate ceramic, take the corresponding amount of Gd2O3, SrCO3 and Al2O3 powder, and add isopropanol as a ball milling medium to make the mixed powder fully dissolved;

[0063] (2) according to the total amount of powder called in step (1) to calculate the required amount of ball mill beads, according to the powder mass ratio, the mass ratio of large ball mill beads to small ball mill beads is equal to 1:1.5:1.5;

[0064] (3) Put the ball mill jar into the planetary ball mill and adjust the rotation speed to 450 rpm for 12 h, so as to obtain a uniformly mixed slurry. Dry the obtained mixed slurry in an oven at 80℃ for 24 h, and then pretreat in a muffle furnace at 1200℃ for 4 h;

[0065] (4) Grind the powder obtained in step (3), pass through a 200 mesh sieve, PVA granulation, and then press into shape. Sinter at 1550℃ in a muffle furnace for 50 h to obtain a high-entropy rare earth strontium aluminate salt thermal barrier coating material.

[0066] The thermal expansion performance is measured as 11.89*10 -6 K -1 (ambient temperature-1500℃).

[0067] Figure 5 is the high-entropy rare earth strontium aluminate (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 The comparison of the thermal expansion performance of Sr2SrAl2O7 and Gd2SrAl2O7 shows that the thermal expansion performance of the high-entropy rare earth strontium aluminate thermal barrier coating material prepared in the present application is obviously higher than that of the rare earth strontium aluminate gadolinium thermal barrier coating material prepared in Comparative Example 1.

[0068] The above not involved, applicable to the prior art.

[0069] Although some specific embodiments of the present application have been described in detail by way of examples, it should be understood that the above examples are only for illustration and are not intended to limit the scope of the present application, and those skilled in the art can make various modifications or supplements to the described specific embodiments or replace them with similar ways without departing from the direction of the present application or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modification, equivalent replacement, improvement, etc. made to the above embodiments according to the technical essence of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing high fracture toughness high-entropy rare earth strontium aluminate thermal barrier coating material, characterized in that: The thermal barrier coating material has a chemical composition formula of (La 0.2 Nd 0.2 Sm 0.2 Eu 0.2 Gd 0.2 )2SrAl2O7; The preparation method is as follows: mixing La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powders according to the chemical formula, wet ball milling to obtain a mixed precursor, drying the mixed precursor, preheating, calcining to obtain the high-entropy rare earth strontium aluminate salt thermal barrier coating material; The preheating temperature is 800-1200℃, and the time is 2-10h; The calcining process is as follows: in a muffle furnace, the calcining temperature is 1350-1550℃, and the time is 2-100h; or in a discharge plasma, the sintering temperature is 1350-1550℃, and the time is at least 5min; The Al2O3 is γ-type nano Al2O3.

2. The production method according to claim 1, wherein The drying temperature is 80℃, and the time is 12-24h.

3. The production method according to claim 1, wherein The purity of the La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, SrCO3 and Al2O3 powders is ≥99.9%.

4. The production method according to claim 1, wherein The liquid for wet ball milling is ethanol or isopropyl alcohol.

5. The production method according to claim 1, wherein The mass ratio of the raw material powders to large ball milling beads and small ball milling beads is 1:1.5:1.5; the diameter of the large ball milling beads is 5mm, and the diameter of the small ball milling beads is 2mm; the ball milling rotation speed is 450rpm, and the time is 12h.

6. A high-entropy rare earth strontium aluminate salt thermal barrier coating material with high fracture toughness, which is prepared by the preparation method in any one of claims 1-5.

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