A high-oxidation-resistance high-entropy metal diboride composite phase material, a preparation method and application thereof

Abstract

The application relates to a high-oxidation-resistance high-entropy metal diboride composite phase material, and belongs to the technical field of ultrahigh-temperature ceramic materials. The high-oxidation-resistance high-entropy metal diboride composite phase material has a chemical formula of (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4. The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powder and block prepared by the application contain (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 and TmB4 two phase structures. The obtained material is subjected to static oxidation test, the oxides generated by Tm and other metal elements form a continuous oxidation layer, fill the gaps, and a high-density oxidation layer is obtained, which can effectively prevent oxygen from entering and reduce the oxidation rate. Therefore, the high-entropy metal diboride composite phase material prepared by the application has excellent oxidation resistance.

Description

[0001] The present application is a divisional application of a patent application with the application date of August 23, 2022, the application number of CN202211011048.3, and the invention name of "High-oxidation-resistance high-entropy metal diboride composite phase material and preparation method thereof". TECHNICAL FIELD

[0002] The present application relates to a high-oxidation-resistance high-entropy metal diboride composite phase material and a preparation method and application thereof, and belongs to the technical field of ultra-high-temperature ceramic materials. BACKGROUND

[0003] Transition metal diborides, as a main member of ultra-high-temperature ceramics, have high melting point, high electrical conductivity, high thermal conductivity, excellent mechanical properties and good chemical stability, and have broad application prospects in hypersonic aircraft and scramjet engines. The high-temperature oxidation resistance of transition metal diborides is extremely important when used at ultra-high temperatures. Most previous studies show that the addition of silicon carbide in transition metal diborides can form borosilicate glass phases in situ, which exhibit better oxidation resistance. However, due to the active oxidation of silicon carbide and the evaporation of silicon dioxide, the dense protective layer will be rapidly destroyed above 1600℃. Therefore, it is urgent to improve the high-temperature oxidation resistance of transition metal diborides. According to the literature reports, the addition of Tm2O3 elements in transition metal diborides has the following effects: (1) improving the stability of the oxidation product liquid phase by reducing the evaporation and increasing the viscosity of the glass phase; (2) improving the density of the porous / without protective oxidation layer and inhibiting the phase transition of the oxidation layer. However, the excessive addition of Tm2O3 has an adverse effect on the high-temperature performance of transition metal diborides. Therefore, it is necessary to design and construct a new structure to overcome this difficulty, which is beneficial to improve the oxidation resistance of metal diborides and promote their application in the field of ultra-high temperature. SUMMARY

[0004] Therefore, the present application designs and prepares a high-oxidation-resistance high-entropy metal diboride composite phase material and a preparation method and application thereof. First, a rare earth metal thulium diboride (TmB2) is introduced into TMB2 through the concept of high entropy. The content of TmB4 is increased by controlling the content of boron carbide in the boron-carbon thermal reduction reaction. The new material is composed of Hf, Zr, Ta, Nb, Tm and B elements, which not only can control the phase structure of the material, but also has very excellent oxidation resistance.

[0005] The purpose of the present application is achieved by the following technical solutions.

[0006] A high-oxidation-resistance high-entropy metal diboride composite phase material, the chemical formula of the high-oxidation-resistance high-entropy metal diboride composite phase material is (Hf 0.2 Zr 0.2 Ta 0.2Nb 0.2 Tm 0.2 )B2 / TmB4; the phase structure contains (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 and TmB4.

[0007] The application further provides a preparation method of the high-oxidation-resistance high-entropy metal diboride composite phase material.

[0008] HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders are mixed according to the stoichiometric ratio of the chemical formula, and are uniformly mixed to obtain mixed powders; the mixed powders are dried in an oven, and then are kept at 1850 DEG C for 1-3 hours to obtain (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powders; the actual addition amount of the B4C powders is 120-135% of the mass of the B4C powders calculated according to the stoichiometric ratio;

[0009] The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powders are loaded into a graphite mold, and are sintered by using discharge-induced plasma sintering under vacuum or inert gas protection atmosphere to obtain the high-oxidation-resistance high-entropy metal diboride composite phase material; the sintering temperature is 1900-2200 DEG C, the pressure is 30-50 MPa, and the holding time is 15-35 min.

[0010] Preferably, the mixing is ball-milling mixing of the HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders in a ball-milling tank; the ball-to-material ratio of the ball-milling mixing is 3-7:1, the rotating speed is 300-500 rpm, and the time is 1-5 h.

[0011] Preferably, the heating rate for heating to 1850 DEG C is 5-10 DEG C / min.

[0012] Preferably, the particle sizes of the HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders are all 0.5-3 μm.

[0013] The application further provides application of the high-oxidation-resistance high-entropy metal diboride composite phase material in the ultra-high-temperature ceramic material

[0014] Beneficial effects:

[0015] (1) The application first designs and prepares a high-oxidation-resistance high-entropy metal diboride composite phase material, (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4, which has excellent phase structure adjustability, and different phase structures can be obtained by controlling the content of boron carbide.

[0016] (2) The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 material has excellent oxidation resistance, the generated Tm2O3 in the oxidation process can reduce the evaporation of the boron glass phase (B2O3) and increase the viscosity of the boron glass phase, thereby improving the hindering effect of the liquid phase product in the oxidation structure on oxygen. Secondly, Tm2O3 can generate low-melting-point oxides with HfO2, ZrO2, Nb2O5 and other transition group oxides, can improve the density of the porous / unsaturated oxidation layer and inhibit the phase change of the oxidation layer, improve the density of the oxidation layer and stabilize the oxidation layer without breaking, thereby improving the oxidation resistance. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0018] Figure 1 X-ray diffraction (XRD) spectrum of the (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powder prepared for Example 1;

[0019] Figure 2 X-ray diffraction (XRD) spectrum of the (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2X-ray diffraction (XRD) pattern of B2 / TmB4;

[0020] Figure 3 (Hf) prepared in Example 1 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 Elemental analysis spectrum of B2 / TmB4;

[0021] Figure 4 (Hf) prepared in Example 1 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 Static oxidation weight gain curve of B2 / TmB4;

[0022] Figure 5 (Hf) prepared in Example 1 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 Scanning electron microscope image of B2 / TmB4 after static oxidation. Detailed Implementation

[0023] The present invention will be further described below with reference to specific embodiments. Unless otherwise specified, the methods described are conventional methods, and the raw materials described are obtainable from publicly available commercial sources.

[0024] In the following embodiments:

[0025] The particle sizes of HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3, and B4C powders are all 0.5–3 μm; Example 1

[0026] (1) Add HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders to a ball mill jar made of nylon according to the chemical formula ratio and ethanol. The ball-to-powder ratio is 6:1. The mixture is ball-milled at 350 rpm for 5 hours to obtain a uniformly mixed powder.

[0027] (2) After drying the mixed powder in an oven at 100℃, it was placed under vacuum and heated to 1850℃ at a heating rate of 10℃ / min and held for 3h to obtain quaternary high-entropy metal diboride powder with the chemical formula (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4;

[0028] (3) The prepared (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powder was loaded into a graphite mold, and bulk sintering was performed in a vacuum atmosphere by spark plasma sintering, with a sintering temperature of 2000°C, a sintering pressure of 40 MPa, and a sintering time of 30 min, to obtain a (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 bulk body.

[0029] The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powder obtained in step (2) was subjected to XRD characterization, and it can be seen from Figure 1 that the diffraction peaks of the (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powder are of two types of hexagonal AlB2 structure and TmB4 structure, wherein the hexagonal AlB2 structure is (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2, and the TmB4 structure is a TmB4 phase, and no diffraction peaks of other phase structures are detected, indicating that the synthesized material is a (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 composite structure material.

[0030] The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 bulk body obtained in step (3) was subjected to XRD characterization, and it can be seen from Figure 2 that the diffraction peaks of the (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2The diffraction peaks of the B2 / TmB4 bulk show an increase in hexagonal AlB2-type structures and a decrease in TmB4-type structures, indicating that some TmB4 phase is incorporated into (Hf). 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 In B2, but the overall structure is still (Hf) 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The composite of B2 / TmB4 phases was determined. Elemental analysis was performed using the EDS function of a scanning electron microscope, based on... Figure 3 The analysis results show that the four metallic elements Hf, Ta, Zr, and Sc are uniformly distributed, and no agglomeration or segregation was detected, indicating that (Hf... 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The B2 block has a uniform quaternary high-entropy structure.

[0031] For the (Hf) prepared in step (3) 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 Elemental analysis of the B2 / TmB4 bulk sample was performed using the EDS function of a scanning electron microscope, based on... Figure 3 The detection and analysis results show that the four metal elements Hf, Ta, Zr and Nb are evenly distributed, and no agglomeration or segregation was detected. Tm element segregation occurred in some areas, which proves that the presence of TmB4 phase caused Tm element segregation.

[0032] For the (Hf) prepared in step (3) 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 Static oxidation tests were performed on the B2 / TmB4 bulk material. Figure 4 The results show that (Hf) 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The oxidation weight gain rate of B2 / TmB4 is significantly lower than that of traditional metal boride materials, indicating that its oxidation resistance is significantly improved.

[0033] For the (Hf) prepared in step (3) 0.2 Zr 0.2 Ta 0.2 Nb0.2 Tm 0.2 After static oxidation testing, the B2 / TmB4 bulk material was characterized by scanning electron microscopy. The results are as follows: Figure 5 As shown. From Figure 5 The results show that (Hf) 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The oxide layer formed after the oxidation of B2 / TmB4 is very dense, and no pores were found in the observation area. This indicates that the oxide formed by Tm element and other metal elements forms a continuous oxide layer, which seals the gaps and can significantly prevent oxygen from entering.

[0034] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A high-oxidation-resistant high-entropy metal diboride composite phase material, characterized in that, The high-oxidation-resistance high-entropy metal diboride composite phase material has a chemical formula of (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4, and contains (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 and TmB4 two phases in a phase structure. The preparation method of the high-oxidation-resistance high-entropy metal diboride composite phase material comprises the following steps: HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders are proportioned according to the stoichiometric ratio of the chemical formula, mixed uniformly to obtain a mixed powder; after the mixed powder is dried in an oven, it is kept at 1850 DEG C for 1-3 hours to obtain (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powder; the actual addition amount of the B4C powder is 135% of the mass of the B4C powder calculated according to the stoichiometric ratio. The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 2. The method for preparing the high-oxidation-resistant, high-entropy metal diboride composite phase material according to claim 1, characterized in that, Comprise the following steps: HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders are proportioned according to the stoichiometric ratio of the chemical formula, mixed uniformly to obtain a mixed powder; after the mixed powder is dried in an oven, it is kept at 1850 DEG C for 1-3 hours to obtain (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 )B2 / TmB4 powder; the actual addition amount of the B4C powder is 120-135% of the mass of the B4C powder calculated according to the stoichiometric ratio. The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 The (Hf 0.2 Zr 0.2 Ta 0.2 Nb 0.2 Tm 0.2 3. The production method according to claim 2, characterized by, The mixing is ball milling mixing of HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders in a ball milling jar; the ball-to-material ratio of the ball milling mixing is 3-7:1, the rotating speed is 300-500 rpm, and the time is 1-5 h.

4. The production method according to claim 2, characterized by, The temperature increasing rate to 1850 DEG C is 5-10 DEG C / min.

5. The preparation method according to claim 2, characterized in that, The particle size of the HfO2, ZrO2, Ta2O5, Nb2O5, Tm2O3 and B4C powders is 0.5-3 mu m.

6. The application of the high-oxidation-resistance high-entropy metal diboride composite phase material in claim 1 in ultra-high-temperature ceramic materials.

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