Copper pyrovanadate-based reinforcement for reducing thermal expansion coefficient of composite materials and preparation method thereof

Abstract

The present invention discloses a copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of a composite material and a preparation method thereof, and relates to a copper pyrovanadate-based reinforcement and a preparation method thereof. In order to solve the problem that the existing copper pyrovanadate-based reinforcement β-Cu2V2O7 has poor negative thermal expansion performance and does not have zero expansion. The copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of a composite material of the present invention is β-Cu 2‑x Ba x V2O7, 0<x≤0.2; β-Cu 2‑x Ba x V2O7 is a zero expansion ceramic. Another copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material of the present invention is β-Cu 2‑x Mn x V2O7, 0<x<2; β-Cu 2‑x Mn x V2O7 is a negative thermal expansion material. The present invention can prepare β-Cu by solid phase sintering. 2‑x Ba x V2O7 solid solution has a simple preparation process, can achieve a large number of products in a single sintering, and no harmful gas release. In order to successfully achieve β-Cu through solid phase sintering combined with rapid cooling 2‑ x Ba x The preparation of V2O7 solid solution provides a simpler and more efficient technical means for its batch synthesis. The prepared samples have significantly improved mechanical properties compared to β-Cu2V2O7 and have the potential to be used independently as structural components.

Description

Technical Field

[0001] The invention relates to a copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of a composite material and a preparation method thereof. Background Art

[0002] In recent years, the rapid development of aerospace, precision instruments, electronic communications, and other fields has placed higher demands on the stability, reliability, and service life of many functional structures and components. In particular, when faced with large temperature fluctuations during service, the mismatch in the thermal expansion coefficients of different components inevitably leads to thermal stress. Under the influence of long-term mechanical fatigue and creep, this can even lead to structural failure of the material, significantly reducing its service life. Therefore, developing material systems with tunable thermal expansion coefficients to avoid or reduce thermal mismatch between materials has become a non-negligible issue in engineering applications.

[0003] The discovery of negative thermal expansion materials provides a way to solve the above problems. A large number of studies have shown that the thermal expansion properties of manganese nitrogen compounds and oxides can be changed through chemical regulation. From the perspective of stability and practical application, the oxide system has greater development potential. In recent years, Cu2V2O7 has come into people's attention. It has three crystal structures, namely orthorhombic α phase, monoclinic β phase and triclinic γ phase. The α phase has almost no negative thermal expansion effect, and the γ phase is a metastable phase and difficult to exist stably. The negative thermal expansion range of pure phase β-Cu2V2O7 is 153-573K, and the thermal expansion coefficient α v -2.7×10 -6 ~10.7×10 -6 K -1 (323-573K), so only the β phase has the development potential for performance control, but during its preparation process, impurities such as the α phase are often present when the cooling rate is low. In addition, from the perspective of material performance requirements, people hope to directly obtain materials with zero expansion effect, or prepare materials with large negative thermal expansion effect, and prepare zero expansion composite materials by compounding with metals. As for pure phase β-Cu2V2O7, its negative thermal expansion performance is not ideal. Its thermal expansion coefficient is only -2.7×10- -6 K -1 , there is a certain gap between it and zero expansion, and it is much higher than the thermal expansion coefficient of ZrW2O8 (-21.9×10 -6 K -1 ), making it difficult to prepare zero-expansion composites. Consequently, β-Cu2V2O7 exhibits poor negative thermal expansion and lacks zero expansion, limiting its application. If the material's thermal expansion properties could be manipulated by introducing other elemental ions, this would offer significant research potential and potential for future applications. Summary of the Invention

[0004] In order to solve the problem that the existing copper pyrovanadate-based reinforcement β-Cu2V2O7 has poor negative thermal expansion performance and does not have zero expansion, the present invention proposes a copper pyrovanadate-based reinforcement with reduced thermal expansion coefficient of composite materials and a preparation method thereof.

[0005] The copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material is β-Cu 2-x Ba x V2O7, 0<x≤0.2; β-Cu 2-x Ba x V2O7 is a zero expansion ceramic.

[0006] The invention discloses a copper pyrovanadate-based reinforcement β-Cu for reducing the thermal expansion coefficient of a composite material. 2-x Ba x The preparation method of V2O7 is carried out according to the following steps:

[0007] 1. Weighing ingredients:

[0008] According to β-Cu 2-x Ba x The molar ratio of elements in V2O7 is as follows: Cu raw material, V raw material and Ba raw material are weighed as raw materials; wherein, 0<x≤0.2

[0009] The Cu raw material is CuO or a decomposable copper-containing compound, and the decomposable copper-containing compound is CuCO3, Cu(OH)2 or Cu2(OH)2CO3;

[0010] The Ba raw material is barium oxide or a Ba compound, and the Ba compound is barium hydroxide or barium carbonate;

[0011] The V raw material is V2O5 or a decomposable vanadium-containing compound, and the decomposable vanadium-containing compound is VO2(C2O4)·2H2O or NH4VO3;

[0012] 2. Powder mixing:

[0013] The raw materials weighed in step 1 are mixed and added into anhydrous ethanol, wet-mixed and ball-milled using anhydrous ethanol as a medium, and then dried to obtain a mixed powder;

[0014] 3. Powder sintering:

[0015] The dried mixed powder is sintered at high temperature and then rapidly cooled to complete the process;

[0016] The high-temperature sintering process is as follows: sintering temperature is 600-900°C; heating rate is 3-50°C / min; holding time is 180-1200min; sintering atmosphere is vacuum, air, argon, nitrogen or helium; cooling method is quenching;

[0017] The present invention has the following beneficial effects:

[0018] 1. The present invention adopts solid phase sintering to prepare β-Cu 2-x Ba x V2O7 (0<x≤0.2) solid solution is a zero expansion ceramic. 1.9 Ba 0.1 V2O7 exhibits a zero expansion effect in the temperature range of 173-473K. Adding this reinforcement during the preparation of composite materials can reduce the thermal expansion coefficient of the composite materials.

[0019] 2. The present invention can prepare β-Cu by solid phase sintering 2-x Ba x V2O7 solid solution has a simple preparation process, can achieve a large number of products sintered in a single time, and no harmful gas is released. 2-x Ba x The V2O7 solid solution is regarded as part of the Cu in Cu2V2O7 2+ Ba 2+ The compound formed by replacing 2+ The ionic radius of Ba is about 73 pm, while 2+ The ionic radius of the ions is about 135pm, and the radius of the latter is nearly twice that of the former. From the perspective of stability, the greater the difference in radius between the replacing ions and the replaced ions, the greater the degree of lattice distortion of the formed compound, the relatively more unstable the system, and the greater the difficulty in material preparation. When the difference in the radius of the two ions is too large, traditional methods usually adopt the following methods: the sol-gel method has the problems of complex preparation process and impurities in the product; the combustion synthesis method has the problems of difficult control of the preparation process and the generation of harmful gases; the co-deposition doping has the problems of high equipment requirements, complex process and low yield. The present invention successfully achieves β-Cu through solid-phase sintering combined with rapid cooling. 2-x Ba x The preparation of V2O7 solid solution provides a simpler and more efficient technical means for its batch synthesis.

[0020] 3. The present invention solves the problem of the presence of α phase and other impurities in the sample when the cooling rate is low by quenching and rapid cooling, and prepares pure single-phase β-Cu 2-x Ba x V2O7 solid solution, and the sample crystal structure remains C2 / c monoclinic structure.

[0021] 4. The existing β-Cu2V2O7 is difficult to sinter. Even after high temperature treatment, it is difficult for the ceramic particles to form an effective bond. The sintered sample still exists in the form of powder. 2-x Bax V2O7 ceramics greatly improve the sintering properties of the base ceramics, and the mechanical properties of the prepared samples are greatly improved compared with β-Cu2V2O7. For example, β-Cu 1.9 Ba 0.1 The hardness of V2O7 reaches 404.5±3.6HV, and it has the potential to be used independently as a structural component.

[0022] Another copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material of the present invention is β-Cu 2-x Mn x V2O7, 0<x<2; β-Cu 2-x Mn x V2O7 is a negative thermal expansion material.

[0023] The β-Cu 2-x Mn x The preparation method of V2O7 is carried out according to the following steps:

[0024] 1. Weighing ingredients:

[0025] According to β-Cu 2-x Mn x The molar ratio of elements in V2O7 is as follows: Cu raw material, V raw material and Mn raw material are weighed as raw materials; wherein 0<x<2;

[0026] The Cu raw material is CuO or a decomposable copper-containing compound, and the decomposable copper-containing compound is CuCO3, Cu(OH)2 or Cu2(OH)2CO3;

[0027] The Mn raw material is MnO or a Mn compound, and the Mn compound is manganese hydroxide or manganese carbonate;

[0028] The V raw material is V2O5 or a decomposable vanadium-containing compound, and the decomposable vanadium-containing compound is VO2(C2O4)·2H2O or NH4VO3;

[0029] 2. Powder mixing:

[0030] The raw materials weighed in step 1 are mixed and added into anhydrous ethanol, wet-mixed and ball-milled using anhydrous ethanol as a medium, and then dried to obtain a mixed powder;

[0031] 3. Powder sintering:

[0032] The dried mixed powder is sintered at high temperature and then rapidly cooled to complete the process;

[0033] The high-temperature sintering process is as follows: sintering temperature is 600-900°C; heating rate is 1-50°C / min; holding time is 180-1200min; sintering atmosphere is vacuum, air, argon, nitrogen or helium; cooling method is quenching;

[0034] The present invention has the following beneficial effects:

[0035] 1. The present invention prepares β-Cu by solid phase sintering 2-x Mn x V2O7 solid solution has a simple preparation process, large synthesis volume, and no harmful gas is released during the process. 1.8 Mn 0.2 The thermal expansion coefficient of V2O7 remains unchanged at low temperatures. The thermal expansion coefficient of the sample in the range of 573-773K is α v -20.5×10 -6 K -1 , and β-Cu2V2O7(α v =-10.7×10 -6 K -1 ), the negative thermal expansion effect is significantly improved. Adding this reinforcement during the preparation of the composite material can reduce the thermal expansion coefficient of the composite material.

[0036] 2. The present invention solves the problem of the presence of α phase and other impurities in the sample when the cooling rate is low by quenching and rapid cooling, and prepares single-phase β-Cu 2-x Mn x V2O7 solid solution, and the sample crystal structure remains C2 / c monoclinic structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 β-Cu prepared in Example 1 1.9 Ba 0.1 XRD patterns of V2O7 at different temperatures;

[0038] Figure 2 β-Cu prepared in Example 1 1.9 Ba 0.1 The curve of the unit cell volume of V2O7 changing with temperature;

[0039] Figure 3 β-Cu prepared in Example 2 1.8 Mn 0.2 XRD patterns of V2O7 at different temperatures;

[0040] Figure 4 β-Cu prepared in Example 2 1.8 Mn 0.2 Curve of the unit cell volume of V2O7 changing with temperature. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is not limited to the specific implementation methods listed below, but also includes any reasonable combination of the specific implementation methods.

[0042] Specific embodiment 1: In this embodiment, the copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material is β-Cu 2-x Ba x V2O7, 0<x≤0.2; β-Cu 2-x Ba x V2O7 is a zero expansion ceramic.

[0043] In this embodiment, β-Cu 2-x Ba x V2O7 (0<x≤0.2) solid solution is a zero expansion ceramic. 1.9 Ba 0.1 V2O7 shows zero expansion effect in the temperature range of 173-473K. 2-x Ba x V2O7 ceramics greatly improve the sintering properties of the base ceramics, and the mechanical properties of the prepared samples are greatly improved compared with β-Cu2V2O7. For example, β-Cu 1.9 Ba 0.1 The hardness of V2O7 reaches 404.5±3.6HV, and it has the potential to be used independently as a structural component.

[0044] Specific embodiment 2: This embodiment reduces the thermal expansion coefficient of the composite material by using the copper pyrovanadate-based reinforcement β-Cu 2-x Ba x The preparation method of V2O7 is carried out according to the following steps:

[0045] 1. Weighing ingredients:

[0046] According to β-Cu 2-x Ba x The molar ratio of elements in V2O7 is as follows: Cu raw material, V raw material and Ba raw material are weighed as raw materials; wherein, 0<x≤0.2

[0047] The Cu raw material is CuO or a decomposable copper-containing compound, and the decomposable copper-containing compound is CuCO3, Cu(OH)2 or Cu2(OH)2CO3;

[0048] The Ba raw material is barium oxide or a Ba compound, and the Ba compound is barium hydroxide or barium carbonate;

[0049] The V raw material is V2O5 or a decomposable vanadium-containing compound, and the decomposable vanadium-containing compound is VO2(C2O4)·2H2O or NH4VO3;

[0050] 2. Powder mixing:

[0051] The raw materials weighed in step 1 are mixed and added into anhydrous ethanol, wet-mixed and ball-milled using anhydrous ethanol as a medium, and then dried to obtain a mixed powder;

[0052] 3. Powder sintering:

[0053] The dried mixed powder is sintered at high temperature and then rapidly cooled to complete the process;

[0054] The high-temperature sintering process is as follows: sintering temperature is 600-900°C; heating rate is 3-50°C / min; holding time is 180-1200min; sintering atmosphere is vacuum, air, argon, nitrogen or helium; cooling method is quenching.

[0055] 1. This embodiment adopts solid phase sintering to prepare β-Cu 2-x Ba x V2O7 (0<x≤0.2) solid solution is a zero expansion ceramic. 1.9 Ba 0.1 V2O7 exhibits a zero expansion effect in the temperature range of 173-473K. Adding this reinforcement during the preparation of composite materials can reduce the thermal expansion coefficient of the composite materials.

[0056] 2. This embodiment can prepare β-Cu by solid phase sintering 2-x Ba x V2O7 solid solution has a simple preparation process, can achieve a large number of products sintered in a single time, and no harmful gas is released. 2-x Ba x The V2O7 solid solution is regarded as part of the Cu in Cu2V2O7 2+ Ba 2+ The compound formed by replacing 2+ The ionic radius of Ba is about 73 pm, while 2+ The ionic radius of the ions is about 135pm, and the radius of the latter is nearly twice that of the former. From the perspective of stability, the greater the difference in radius between the replacing ions and the replaced ions, the greater the degree of lattice distortion of the formed compound, the relatively more unstable the system, and the greater the difficulty in material preparation. When the difference in the radius of the two ions is too large, traditional methods usually adopt the following methods: the sol-gel method has the problems of complex preparation process and impurities in the product; the combustion synthesis method has the problems of difficult control of the preparation process and the generation of harmful gases; the co-deposition doping has the problems of high equipment requirements, complex process and low yield. This embodiment successfully realizes β-Cu through solid-phase sintering combined with rapid cooling. 2-x Ba xThe preparation of V2O7 solid solution provides a simpler and more efficient technical means for its batch synthesis.

[0057] 3. This embodiment solves the problem of the presence of α phase and other impurities in the sample when the cooling rate is low by quenching and rapid cooling, and prepares pure single-phase β-Cu 2-x Ba x V2O7 solid solution, and the sample crystal structure remains C2 / c monoclinic structure.

[0058] 4. The existing β-Cu2V2O7 is difficult to sinter. Even after high temperature treatment, it is difficult for the ceramic particles to form an effective bond. The sintered sample still exists in the form of powder. 2-x Ba x V2O7 ceramics greatly improve the sintering properties of the base ceramics, and the mechanical properties of the prepared samples are greatly improved compared with β-Cu2V2O7. For example, β-Cu 1.9 Ba 0.1 The hardness of V2O7 reaches 404.5±3.6HV, and it has the potential to be used independently as a structural component.

[0059] Specific embodiment three: This embodiment differs from specific embodiment two in that: in step one, the purity of the Cu raw material, the V raw material and the Ba raw material is 98-99.99%, and the average particle size is 0.1-500 μm.

[0060] Specific embodiment 4: This embodiment differs from specific embodiment 2 in that the mass of the anhydrous ethanol in step 2 is 0.2-3 times the mass of the raw material.

[0061] Specific embodiment 5: This embodiment differs from specific embodiment 2 in that: the wet mixing ball milling process in step 2 is: the ball-to-material ratio is (1-20):1, the rotation speed is 20-100 rpm, and the time is 4-72h.

[0062] Specific embodiment six: In this embodiment, the copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material is β-Cu 2-x Mn x V2O7, 0<x<2; β-Cu 2-x Mn x V2O7 is a negative thermal expansion material.

[0063] The β-Cu prepared by solid phase sintering in this embodiment 2-x Mn x V2O7 solid solution is a negative thermal expansion material, in which β-Cu 1.8 Mn 0.2 The thermal expansion coefficient of V2O7 remains unchanged at low temperatures. The thermal expansion coefficient of the sample in the range of 573-773K is αv -20.5×10 -6 K -1 , and β-Cu2V2O7(α v =-10.7×10 -6 K -1 ), the negative thermal expansion effect is significantly improved.

[0064] Specific embodiment seven: β-Cu 2-x Mn x The preparation method of V2O7 is carried out according to the following steps:

[0065] 1. Weighing ingredients:

[0066] According to β-Cu 2-x Mn x The molar ratio of elements in V2O7 is as follows: Cu raw material, V raw material and Mn raw material are weighed as raw materials; wherein 0<x<2;

[0067] The Cu raw material is CuO or a decomposable copper-containing compound, and the decomposable copper-containing compound is CuCO3, Cu(OH)2 or Cu2(OH)2CO3;

[0068] The Mn raw material is MnO or a Mn compound, and the Mn compound is manganese hydroxide or manganese carbonate;

[0069] The V raw material is V2O5 or a decomposable vanadium-containing compound, and the decomposable vanadium-containing compound is VO2(C2O4)·2H2O or NH4VO3;

[0070] 2. Powder mixing:

[0071] The raw materials weighed in step 1 are mixed and added into anhydrous ethanol, wet-mixed and ball-milled using anhydrous ethanol as a medium, and then dried to obtain a mixed powder;

[0072] 3. Powder sintering:

[0073] The dried mixed powder is sintered at high temperature and then rapidly cooled to complete the process;

[0074] The high-temperature sintering process is as follows: sintering temperature is 600-900°C; heating rate is 1-50°C / min; holding time is 180-1200min; sintering atmosphere is vacuum, air, argon, nitrogen or helium; cooling method is quenching.

[0075] 1. This embodiment prepares β-Cu by solid phase sintering 2-x Mn x V2O7 solid solution has a simple preparation process, large synthesis volume, and no harmful gas is released during the process. 1.8 Mn0.2 The thermal expansion coefficient of V2O7 remains unchanged at low temperatures. The thermal expansion coefficient of the sample in the range of 573-773K is α v -20.5×10 -6 K -1 , and β-Cu2V2O7(α v =-10.7×10 -6 K -1 ), the negative thermal expansion effect is significantly improved. Adding this reinforcement during the preparation of the composite material can reduce the thermal expansion coefficient of the composite material.

[0076] 2. This embodiment solves the problem of the presence of α phase and other impurities in the sample when the cooling rate is low by quenching and rapid cooling, and prepares single-phase β-Cu 2-x Mn x V2O7 solid solution, and the sample crystal structure remains C2 / c monoclinic structure.

[0077] Specific embodiment eight: This embodiment differs from specific embodiment seven in that: in step one, the purity of the Cu raw material, the V raw material and the Mn raw material is 98-99.99%, and the average particle size is 0.1-500 μm.

[0078] Specific embodiment 9: This embodiment differs from specific embodiment 7 in that the mass of anhydrous ethanol in step 2 is 0.2-3 times the mass of the raw material. The wet mixing ball milling process in step 2 is as follows: the ball-to-material ratio is (1-20):1, the rotation speed is 20-100 rpm, and the time is 4-72 hours.

[0079] Specific embodiment ten: This embodiment differs from specific embodiment seven in that: the wet mixing ball milling process in step two is: the ball-to-material ratio is (1-20):1, the rotation speed is 20-100 rpm, and the time is 4-72h.

[0080] Example 1:

[0081] The copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material is β-Cu 1.9 Ba 0.1 V2O7; β-Cu 1.9 Ba 0.1 V2O7 is a zero expansion ceramic.

[0082] The invention discloses a copper pyrovanadate-based reinforcement β-Cu for reducing the thermal expansion coefficient of a composite material. 1.9 Ba 0.1 The preparation method of V2O7 is carried out according to the following steps:

[0083] 1. Weighing ingredients:

[0084] According to β-Cu 1.9 Ba0.1 The molar ratio of each element in V2O7 was used to weigh CuO, V2O5 and BaCO3 as raw materials;

[0085] The purity of the CuO, V2O5 and BaCO3 is 99.99%, and the particle size of CuO is D 50 10μm; the particle size D of V2O5 50 1 μm; BaCO3 particle size D 50 10μm;

[0086] 2. Powder mixing:

[0087] The raw materials weighed in step 1 are mixed and added into anhydrous ethanol, wet-mixed and ball-milled using anhydrous ethanol as a medium, and then dried to obtain a mixed powder;

[0088] The mass of the anhydrous ethanol is 0.5 times the mass of the raw material;

[0089] The wet mixing ball milling process is as follows: the ball-to-material ratio is 2:1, the rotation speed is 80 rpm, and the time is 24 hours;

[0090] 3. Powder sintering:

[0091] The dried mixed powder is sintered at high temperature and then rapidly cooled to complete the process;

[0092] The high-temperature sintering process is as follows: sintering temperature is 750°C; heating rate is 5°C / min; holding time is 240min; sintering atmosphere is air atmosphere; cooling method is quenching;

[0093] from Figure 1 It can be seen that within the test temperature range, the diffraction peaks of the samples are in good agreement with those of β-Cu2V2O7. This proves that high-purity β-Cu2V2O7 was successfully prepared by solid-phase sintering and rapid cooling in this embodiment. 1.9 Ba 0.1 V2O7 single-phase solid solution, on the other hand, proves that the crystal structure of the sample does not change within the test temperature range. In other words, although Ba 2+ The introduction of β-Cu leads to a large degree of lattice distortion, but 1.9 Ba 0.1 V2O7 can still exist stably within the test temperature range. According to the lattice constant and crystal face angle, the change of unit cell volume with temperature is calculated as follows: Figure 2 As shown in the figure, it can be seen that in the range of 173-373K, the volume of the sample unit cell does not change much. According to calculations, the average thermal expansion coefficient α of the sample in this temperature range is v About 0.44×10 -6 K -1In other words, the sample exhibits a zero expansion effect in the temperature range of 173-473K, and the decrease in the thermal expansion coefficient of the sample at high temperature is also consistent with the change law of the lattice constant.

[0094] Example 2:

[0095] The copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material in this embodiment is β-Cu 1.8 Mn 0.2 V2O7, β-Cu 1.8 Mn 0.2 V2O7 is a negative thermal expansion material.

[0096] The β-Cu 1.8 Mn 0.2 The preparation method of V2O7 is carried out according to the following steps:

[0097] 1. Weighing ingredients:

[0098] According to β-Cu 1.8 Mn 0.2 The molar ratio of each element in V2O7 was used to weigh CuO, MnO and V2O5 as raw materials;

[0099] The purity of the CuO, MnO and V2O5 is 99.99%, and the particle size of CuO is D 50 10μm; the particle size D of V2O5 50 1 μm; the particle size of MnO D 50 5μm;

[0100] 2. Powder mixing:

[0101] The raw materials weighed in step 1 are mixed and added into anhydrous ethanol, wet-mixed and ball-milled using anhydrous ethanol as a medium, and then dried to obtain a mixed powder;

[0102] The mass of the anhydrous ethanol is 0.5 times the mass of the raw material;

[0103] The wet mixing ball milling process is as follows: the ball-to-material ratio is 2:1, the rotation speed is 80 rpm, and the time is 24 hours;

[0104] 3. Powder sintering:

[0105] The dried mixed powder is sintered at high temperature and then rapidly cooled to complete the process;

[0106] The high-temperature sintering process is as follows: sintering temperature is 730°C; heating rate is 5°C / min; holding time is 240min; sintering atmosphere is air atmosphere; cooling method is quenching;

[0107] Example 2 Preparation of β-Cu 1.8 Mn 0.2V2O7 ceramics can be synthesized in large quantities through solid phase sintering, and the preparation process is simple. Combined with rapid cooling, a single-phase solid solution can be obtained, and the solid solution crystal can maintain a good C2 / c monoclinic structure. 2+ The introduction of β-Cu can significantly improve and reduce the thermal expansion coefficient of the material at high temperature. 1.8 Mn 0.2 V2O7 can make the thermal expansion coefficient of the sample α in the range of 573-773K without affecting the thermal expansion coefficient at low temperature. v -20.5×10 -6 K -1 , and β-Cu2V2O7(α v =-10.7×10 -6 K -1 ), the negative thermal expansion effect is significantly improved.

[0108] from Figure 3 It can be seen that within the test temperature range, the diffraction peaks of the samples are in good agreement with those of β-Cu2V2O7. This proves that the present invention has successfully produced high-purity β-Cu2V2O7 by solid-phase sintering and rapid cooling. 1.8 Mn 0.2 V2O7 single-phase solid solution, on the other hand, proves that the crystal structure of the sample does not change within the test temperature range. According to the lattice constant and crystal plane angle, the change law of unit cell volume with temperature is calculated as follows Figure 4 As shown in the figure, it can be seen that in the range of 573-773K, the unit cell volume of the sample decreases rapidly. According to calculations, the average thermal expansion coefficient α of the sample in this temperature range is v About -20.5×10 -6 K -1 , and β-Cu2V2O7(α v =-10.7×10 -6 K -1 ), the negative thermal expansion effect is significantly improved.

Claims

1. A copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of a composite material, characterized by: The copper pyrovanadate-based reinforcement for reducing the thermal expansion coefficient of the composite material is β-Cu 2-x Ba x V2O7, 0<x≤0.2; β-Cu 2-x Ba x V2O7 is a zero expansion ceramic, the β-Cu 1.9 Ba 0.1 V2O7 exhibits zero expansion effect in the temperature range of 173-473K.

2. The copper pyrovanadate-based reinforcement β-Cu for reducing the thermal expansion coefficient of the composite material according to claim 1 2-x Ba x The preparation method of V2O7 is characterized by: Copper pyrovanadate-based reinforcement β-Cu for reducing thermal expansion coefficient of composite materials 2-x Ba x The preparation method of V2O7 is carried out according to the following steps:

1. Weighing ingredients: According to β-Cu 2-x Ba x The molar ratio of elements in V2O7 is as follows: Cu raw material, V raw material and Ba raw material are weighed as raw materials; wherein, 0<x≤0.2 The Cu raw material is CuO or a decomposable copper-containing compound, and the decomposable copper-containing compound is CuCO3, Cu(OH)2 or Cu2(OH)2CO3; The Ba raw material is barium oxide or a Ba compound, and the Ba compound is barium hydroxide or barium carbonate; The V raw material is V2O5 or a decomposable vanadium-containing compound, and the decomposable vanadium-containing compound is VO2(C2O4)·2H2O or NH4VO3; 2. Powder mixing: The raw materials weighed in step 1 are mixed and added into anhydrous ethanol, wet-mixed and ball-milled using anhydrous ethanol as a medium, and then dried to obtain a mixed powder; 3. Powder sintering: The dried mixed powder is sintered at high temperature and then rapidly cooled to complete the process; The high-temperature sintering process is as follows: sintering temperature is 600-900°C; heating rate is 3-50°C / min; holding time is 180-1200min; sintering atmosphere is vacuum, air, argon, nitrogen or helium; cooling method is quenching.

3. The copper pyrovanadate-based reinforcement β-Cu for reducing the thermal expansion coefficient of the composite material according to claim 2 2-x Ba x The preparation method of V2O7 is characterized by: The purity of the Cu raw material, the V raw material and the Ba raw material in step 1 is 98-99.99%, and the average particle size is 0.1-500 μm.

4. The copper pyrovanadate-based reinforcement β-Cu for reducing the thermal expansion coefficient of the composite material according to claim 2 2-x Ba x The preparation method of V2O7 is characterized by: The mass of the anhydrous ethanol in step 2 is 0.2-3 times the mass of the raw material.

5. The copper pyrovanadate-based reinforcement β-Cu for reducing the thermal expansion coefficient of the composite material according to claim 2 2-x Ba x The preparation method of V2O7 is characterized by: The wet mixing ball milling process in step 2 is as follows: the ball-to-material ratio is (1-20):1, the rotation speed is 20-100 rpm, and the time is 4-72 hours.

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