(Ti, Zr, Hf, Ta, Nb) B2High-entropy ceramic powder and preparation method thereof
Technical Field
The invention belongs to the technical field of preparation of high-entropy compounds, and particularly relates to (Ti, Zr, Hf, Ta, Nb) B2High-entropy ceramic powder and a preparation method thereof.
Background
The high-entropy ceramic is a novel ceramic material which appears recently, and the appearance of the ceramic material enriches the system of the existing ceramic material. The concept of high entropy material was proposed by professor yu shi of the Qinghua university of Taiwan in the end of the 90 s of the 20 th century and was defined as element types of 5 or more. At present, research on high-entropy materials is mainly focused on the field of alloys, the specific strength of the high-entropy alloys is superior to that of the traditional alloys, and the fracture resistance, tensile strength, corrosion resistance and oxidation resistance of the high-entropy alloys are superior to those of the traditional alloys. Recently, high-entropy ceramics have received much attention as a new ceramic material. Compared with the traditional ceramics, the high-entropy ceramics has higher hardness and melting point, better corrosion resistance, biocompatibility, electrochemical performance and the like, and has greater development potential in the fields of ultrahigh temperature, biomedicine, energy and the like. The synthesis of the high-entropy ceramic powder is very important for the preparation and the application of the high-entropy ceramic. However, few reports are reported on the synthesis method of the high-entropy ceramic powder at home and abroad at present.
The literature: "Feng L, Fahrenholtz W G, Hilmas G E, et al, Synthesis of single-phase high-entropy carbide powders, Scripta materials, 2019, 162: 90-93" introduces a method for preparing high-entropy carbide ceramic powder. The method comprises two steps: firstly, HfO is added2、ZrO2、TiO2、Nb2O5And Ta2O5Uniformly mixing the five oxide powders with the C powder, and reacting at 1600 ℃ to obtain carbide powder; then the carbide powder is subjected to heat treatment at 2000 ℃ to prepare the (Hf, Zr, Ti, Nb, Ta) C high-entropy ceramic powder. The method has the defects of high preparation temperature (2000 ℃), complex process, larger grain size (average grain size of 500 nm) and uneven components of the prepared high-entropy ceramic powder, and the popularization and the application of the method are seriously limited.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide (Ti, Zr, Hf, Ta, Nb) B2High-entropy ceramic powder and preparation method thereof, wherein ZrO is used in the method2Powder, TiO2Powder, HfO2Powder and Nb2O5Powder, Ta2O5The powder and the B powder are taken as raw materials, and the (Ti, Zr, Hf, Ta, Nb) B with uniform components and fine grains is directly and successfully prepared by boron thermal reduction reaction at lower temperature2High entropy ceramic powder. The method has simple process and low synthesis temperature, and the prepared (Ti, Zr, Hf, Ta, Nb) B 2The high-entropy ceramic powder has uniform components and fine grains (the average grain size is 200-300 nm).
The purpose of the invention is realized by the following technical scheme.
(Ti, Zr, Hf, Ta, Nb) B2The preparation method of the high-entropy ceramic powder comprises the following steps:
(1) weighing TiO2Powder, ZrO2Powder, HfO2Powder and Nb2O5Powder, Ta2O5Mixing the powder and B (boron) powder as raw materials, and grinding to obtain mixed powder;
(2) sintering the mixed powder obtained in the step (1), introducing Ar gas for protection in the sintering process, and cooling after sintering to finally obtain the (Ti, Zr, Hf, Ta, Nb) B2High entropy ceramic powder.
In step (1), the molar ratio of Ti, Zr, Hf, Nb and Ta is 1:1:1:1:1, and the molar ratio of the total amount of the five oxides to the B powder is 1:4.5 to 1: 5.
Further, in the step (1), TiO2Powder, ZrO2Powder, HfO2Powder and Nb2O5Powder and Ta2O5The purity of the powder is more than or equal to 99 percent, and the purity of the powder is TiO2The particle size of the powder is 50-200 nm; ZrO (ZrO)2Powder, HfO2Powder and Nb2O5Powder and Ta2O5The particle size of the powder is 1-3 mu m; the purity of the B powder is more than or equal to 99.9%, and the particle size is 0.7-0.9 μm.
Further, the grinding in the step (1) is to put the raw materials into a polytetrafluoroethylene ball mill pot of a ball mill and add ZrO 2The ball-milled beads were ground into a mixed powder.
Further, in the step (1), the mass ratio of the ball milling beads used in the grinding to the raw materials is 5: 1-20: 1; the rotating speed of the ball mill is 300-500 r/min; the ball milling time is 5-20 h.
Further, in the step (2), the temperature rise rate is 5-10 ℃/min in the sintering process, the sintering temperature is 1650-1750 ℃, and the temperature is kept for 1-3 h after the sintering temperature is reached.
The invention is prepared by TiO2、ZrO2、HfO2、Ta2O5And Nb2O5Performing boron thermal reduction reaction with B to directly synthesize (Ti, Zr, Hf, Ta, Nb) B2High entropy ceramic powder.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the preparation method has the advantages of simple process, low preparation temperature and high efficiency, and is beneficial to large-scale industrial production;
(2) the high-entropy ceramic powder synthesized by the preparation method disclosed by the invention is fine (200-300 nm) in crystal grain and uniform in component, so that the method has the potential of being developed into large-scale industrial production.
Drawings
FIG. 1 shows (Ti, Zr, Hf, Ta, Nb) B synthesized in example 12XRD pattern of the high entropy ceramic powder;
FIG. 2 shows (Ti, Zr, Hf, Ta, Nb) B synthesized in example 12SEM picture and EDS energy spectrum element distribution diagram of high entropy ceramic powder.
Detailed Description
The technical solutions of the present invention are further described in detail below with reference to specific examples and drawings, but the scope and implementation of the present invention are not limited thereto.
TiO used in examples 1 to 3 of the present invention2The purity of the powder is more than or equal to 99%, and the particle size is 50-200 nm; ZrO (ZrO)2The purity of the powder is more than or equal to 99%, and the particle size is 50-200 nm; HfO2The purity of the powder is more than or equal to 99%, and the particle size is 1-3 mu m; nb2O5The purity of the powder is more than or equal to 99%, and the particle size is 1-3 mu m; ta2O5The purity of the powder is more than or equal to 99%, and the particle size is 1-3 mu m; the purity of the B powder is more than or equal to 99.9%, and the particle size is 0.7-0.9 μm.
Example 1
(Ti, Zr, Hf, Ta, Nb) B2The preparation of the high-entropy ceramic powder comprises the following steps:
(1) 0.48 g of TiO was weighed out separately2Powder, 0.74 g of ZrO2Powder, 1.26 g HfO2Powder, 1.32 g Ta2O5Powder, 0.80 g Nb2O5The powder and 1.23 g B powder were placed in a 50 ml Teflon ball mill jar and 76.00 g ZrO was added2And (4) grinding the balls. Placing the ball milling tank in a ball mill to perform ball milling for 13 hours at the rotating speed of 400 r/min to obtain mixed powder;
(2) putting the mixed powder obtained in the step (1) into a graphite crucible with a cover, tightly covering, and putting the mixed powder into the graphite crucible with the coverThe graphite crucible is put into a vacuum atmosphere furnace and the atmosphere furnace is vacuumized, and after the vacuum is vacuumized for 10 min, the vacuum index value reaches 10 -2Introducing Ar gas to normal pressure under MPa, then heating the furnace temperature from room temperature to 1700 ℃ at the heating rate of 8 ℃/min, and preserving the temperature for 2 h; then, turning off the power supply, naturally cooling to room temperature, and introducing Ar gas for protection in the whole process;
FIG. 1 shows (Ti) prepared in this example0.2Zr0.2Hf0.2Ta0.2Nb0.2)B2XRD pattern of high-entropy ceramic powder, which shows that (Ti) is prepared0.2Zr0.2Hf0.2Ta0.2Nb0.2)B2The high-entropy ceramic powder is pure phase and does not contain other impurity phases. FIG. 2 shows the preparation of this example (Ti)0.2Zr0.2Hf0.2Ta0.2Nb0.2)B2SEM image and element distribution diagram of high-entropy ceramic powder, as shown by a in FIG. 2, (Ti) synthesized under the above conditions0.2Zr0.2Hf0.2Ta0.2Nb0.2)B2The high-entropy ceramic powder has small grain size, the average grain size is 200-300 nm, and five constituent elements of Hf, Ta, Ti, Nb and Zr are uniformly distributed according to b-f in figure 2.
Example 2
(Ti, Zr, Hf, Ta, Nb) B2The preparation of the high-entropy ceramic powder comprises the following steps:
0.48 g of TiO was weighed out separately2Powder, 0.74 g of ZrO2Powder, 1.26 g HfO2Powder, 1.32 g Ta2O5Powder, 0.80 g Nb2O5The powder and 1.17 g B powder were placed in a 50 ml Teflon ball mill jar and 28.85 g ZrO was added2And (4) grinding the balls. Placing the ball milling tank in a ball mill to ball mill for 5 hours at the rotating speed of 300 r/min to obtain mixed powder;
putting the mixed powder obtained in the step (1) into a graphite crucible with a cover, tightly covering, putting the graphite crucible into a vacuum atmosphere furnace, vacuumizing the atmosphere furnace for 10 min to enable the vacuum index value to reach 10 -2Introducing Ar gas to normal pressure under MPa, and then introducing 5Raising the temperature of the furnace from room temperature to 1650 ℃ at a temperature raising rate of min/min, and keeping the temperature for 1 h; then the power supply is turned off to naturally cool to the room temperature, the whole process is protected by Ar gas, and the (Ti, Zr, Hf, Ta, Nb) B synthesized under the condition is2The high-entropy ceramic powder is a pure phase with an average grain size of about 200 nm, as shown in fig. 1 and 2 of example 1.
Example 3
(Ti, Zr, Hf, Ta, Nb) B2The preparation of the high-entropy ceramic powder comprises the following steps:
(1) 0.48 g of TiO was weighed out separately2Powder, 0.74 g of ZrO2Powder, 1.26 g HfO2Powder, 1.32 g Ta2O5Powder, 0.80 g Nb2O5The powder and 1.30 g B powder were placed in a Teflon ball mill jar with a capacity of 50 ml and 118.00 g ZrO was added2And (4) grinding the balls. Placing the ball milling tank in a ball mill to ball mill for 20 hours at the rotating speed of 500 r/min to obtain mixed powder;
putting the mixed powder obtained in the step (1) into a graphite crucible with a cover, tightly covering, putting the graphite crucible into a vacuum atmosphere furnace, vacuumizing the atmosphere furnace for 10 min to enable the vacuum index value to reach 10-2Introducing Ar gas to normal pressure under MPa, then heating the furnace temperature to 1750 ℃ from room temperature at the heating rate of 10 ℃/min, and preserving the temperature for 3 h; then the power supply is turned off to naturally cool to the room temperature, the whole process is protected by Ar gas, and the (Ti, Zr, Hf, Ta, Nb) B synthesized under the condition is 2The high-entropy ceramic powder is pure phase with an average grain size of about 400 nm, as shown in fig. 1 and 2 of example 1.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.