Miscibility gap alloy, and preparation method therefor and use thereof

Abstract

The present invention belongs to the technical field of thermal energy storage, and particularly relates to a miscibility gap alloy, and a preparation method therefor and the use thereof. In the present invention, graphite and sodium silicate are used as a mixed matrix, a silica sol is introduced, and mixing is performed to form a first component; a metal powder is used as a second component; with the first component serving as a framework and the second component serving as a carrier, the two components are mixed and then pressed to obtain a first alloy billet; the silica sol, a graphite powder and water are mixed to form a slurry, namely, a third component; the third component serves as a protective layer and is sprayed onto a surface of the first alloy billet to prepare a second alloy billet; and the second alloy billet is pressed at room temperature and then sintered to obtain the miscible interstitial alloy. The miscibility gap alloy prepared in the present invention has a heat conductivity coefficient of 61.7 W / mK to 69.3 W / mK, and has good heat-conducting properties and a good compressive strength; and compared with the prior art, the production period for the billet of the miscibility gap alloy prepared in the present invention is shortened by 86%.

Description

A miscible interstitial alloy and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of thermal energy storage, and in particular relates to a miscible interstitial alloy and a preparation method and application thereof. Background Art

[0002] Miscible interstitial alloys are a low-cost, low-pollution, high-heat storage energy storage material developed by the University of Newcastle, Australia. This material can store large amounts of renewable energy as heat for a long time, and has broad application prospects, especially in the fields of peak-shaving energy storage and thermal energy transfer.

[0003] International Patent No. WO 2014 / 063191 A1 defines a miscible interstitial alloy as a novel heat storage material comprising a first component and a second component, wherein the first component is a dense, continuous, heat-conducting matrix, and the second component is an assembly of particles dispersed throughout the matrix of the first component. The first and second components are completely or partially immiscible, and the melting temperature of the first component is significantly higher than that of the second component. The miscible interstitial alloy is contacted with a heat source to provide a material containing a large amount of heat. This international patent provides a broad definition of miscible interstitial alloys but does not specifically address their production process.

[0004] In the prior art, engineering development and heat storage field tests have been carried out on miscible interstitial alloys. The currently disclosed production process for miscible interstitial alloys is: mixing the first component and the second component to obtain a billet; pressing the billet at room temperature and sintering it at high temperature to obtain a miscible interstitial alloy. Among them, the first component is composed of graphite powder and a binder, and the binder is generally a saturated sodium silicate aqueous solution or a saturated sodium metaaluminate solution. The initial state of the first component is a solid-liquid mixed clay state, so the processing of the first component requires drying and a series of subsequent complex processing processes, and finally it is prepared into a powder with a particle size of ≤40μm. However, in the prior art, drying alone requires 24h to 36h, which makes the billet processing process time-consuming, resulting in a complex and time-consuming preparation process for miscible interstitial alloys. Summary of the Invention

[0005] In order to solve the problem of complex and time-consuming preparation process of miscible interstitial alloys in the above-mentioned preparation process, the present invention provides a miscible interstitial alloy and a preparation method and application thereof.

[0006] The miscible interstitial alloy of the present invention comprises a first component as a skeleton, a second component as a carrier, and a third component as a protective layer. The first and second components are mixed and then pressed to obtain a first alloy billet; the third component is sprayed on the surface of the first alloy billet to form a protective layer to obtain a second alloy billet; and the second alloy billet is pressed and sintered at room temperature to obtain the miscible interstitial alloy. The first component comprises a mixed matrix of graphite and sodium silicate, into which silica sol is introduced. By introducing silica sol, which has superior structural properties and is non-hygroscopic, into the first component, and directly mixing graphite powder with sodium silicate powder and silica sol, the first component is prepared. This reduces the effect of sodium silicate, which has poor thermal conductivity, on the thermal conductivity of the first component. Furthermore, the non-hygroscopic nature of silica sol is utilized to mitigate the effect of sodium silicate's susceptibility to moisture absorption in air, thereby preventing any impact on the structural properties of the miscible interstitial alloy skeleton. More importantly, by optimizing the mixing method of the first component, the complex and time-consuming billet preparation process is further resolved.

[0007] Furthermore, in the prior art, the mass fraction of sodium silicate in the first component is 38.5 wt%. The large amount of sodium silicate added reduces the thermal conductivity of the miscible interstitial alloy. Furthermore, sodium silicate absorbs moisture significantly in the air, rapidly degrading its structural properties. This increases the storage cost of the miscible interstitial alloy and reduces its service life. More importantly, during the high-temperature sintering process, since the sintering temperature is 50°C to 80°C higher than the melting point of the second component, the surface of the miscible interstitial alloy experiences severe sweating of the second component, leading to cracking and moisture absorption, reducing its service life.

[0008] The present invention introduces silica sol with better structural properties and no moisture absorption into the first component, and utilizes the non-hygroscopic property of silica sol to weaken the effect of sodium silicate's easy moisture absorption in the air, thereby avoiding the impact on the structural properties of the miscible interstitial alloy skeleton. At the same time, on the basis of the first component and the second component, a thinner third component layer is introduced on the surface of the miscible interstitial alloy, and the third component is composed of graphite powder, silica sol and water. The sintered product of silica sol has the advantages of high structural strength and no moisture absorption, so that the single-component layer has the advantages of preventing the second component from sweating, high density, structural strength and no surface cracking; and after the third component is introduced, it will not affect the original excellent thermal conductivity and energy storage capacity of the miscible interstitial alloy. The first purpose of the present invention is to provide a method for preparing a miscible interstitial alloy, comprising the following steps:

[0009] S1. Graphite and sodium silicate are used as a mixed matrix, and silica sol is introduced and mixed to form a first component.

[0010] Metal powder is used as the second component.

[0011] The first component is used as a skeleton and the second component is used as a carrier, and they are mixed to prepare a blank.

[0012] It should be noted that the first component, serving as the dense, continuous, thermally conductive matrix of the miscible interstitial alloy and also the skeleton of the miscible interstitial alloy, requires good thermal conductivity and high structural strength. The first component in the prior art consists of graphite powder and a binder, with sodium silicate serving as the binder. However, sodium silicate has a low thermal conductivity of approximately 1 W / (m·K). This low thermal conductivity results in poor thermal conductivity of the resulting miscible interstitial alloy, thereby affecting the alloy's energy storage performance. Furthermore, sodium silicate absorbs moisture very strongly in the air, which rapidly degrades the structural properties of the miscible interstitial alloy, leading to poor mechanical properties and a reduced service life. Therefore, the unique feature of the present invention is that, by introducing silica sol, which has extremely weak moisture absorption after sintering, into the first component, on the one hand, the addition of silica sol reduces the content of sodium silicate in the first component, thereby reducing the influence of sodium silicate with poor thermal conductivity on the thermal conductivity of the first component, thereby affecting the thermal conductivity of the miscible interstitial alloy; on the other hand, the extremely weak moisture absorption property of silica sol after sintering is utilized to reduce the influence of sodium silicate's easy moisture absorption in the air, thereby avoiding the influence on the skeletal structural properties of the miscible interstitial alloy, thereby reducing the storage cost of the miscible interstitial alloy and improving the service life of the miscible interstitial alloy.

[0013] Furthermore, by optimizing the mixing method of the first component, graphite powder, sodium silicate powder, and silica sol are directly mixed to obtain the first component. This mixing method of the first component of the present invention avoids the conventional process of mixing graphite powder with a saturated aqueous sodium silicate solution to obtain a mixed clay, which then requires a series of complex processing steps such as drying, thus resolving the problem of a complex and time-consuming blank preparation process.

[0014] By controlling the mass fractions of sodium silicate and silica sol in the first component to be significantly lower than the 38.5 wt% mass fraction of sodium silicate in a saturated aqueous sodium silicate solution used in the prior art, the present invention prevents the addition of large amounts of sodium silicate from affecting the thermal conductivity of the miscible interstitial alloy, which in turn can lead to a decrease in the structural properties of the miscible interstitial alloy. Therefore, the present invention preferably includes a mass fraction of sodium silicate of 2 wt% to 6 wt% in the first component, and a mass fraction of silica sol of 0.5 wt% to 2.5 wt%. Furthermore, to ensure uniform mixing of the first component, the present invention preferably employs mechanical stirring for 15 to 30 minutes.

[0015] It should be noted that the second component, as the primary carrier of phase change energy storage, is dispersed as particles throughout the continuous thermally conductive matrix of the first component. The second component exhibits high latent heat of fusion, high energy storage, high thermal conductivity, and no supercooling. The preferred second component of the present invention is a metal powder selected from the group consisting of Al, Cu, Zn, Sn, and Al-Si alloy powders, with a particle size of 100 to 500 μm.

[0016] Preferably, the mass fraction of graphite powder in the first component is 48 wt% to 51 wt%.

[0017] Preferably, the mass fraction of the first component in the blank is 50 wt%.

[0018] S2. Pressing the blank at room temperature to form a first alloy blank.

[0019] The uniformly mixed billet powder is placed in a first mold and pressed at room temperature to form a first alloy billet. Preferably, in the present invention, the pressing pressure is 5 MPa to 8 MPa, and the holding time is 5 min to 10 min.

[0020] S3. Mixing silica sol, graphite powder and water to form a slurry, i.e., the third component.

[0021] The third component is used as a protective layer and sprayed on the surface of the first alloy billet to form a second alloy billet.

[0022] It should be noted that the present invention introduces a thin single-component layer of a third component onto the surface of the first alloy billet to form a second alloy billet. Because the sintering temperature is higher than the melting point of the second component, if the first alloy billet, which is a mixture of the first and second components, is directly sintered at high temperature without uniformly wrapping the third component around the outer layer of the first alloy billet as a protective layer, the second component on the surface of the miscible interstitial alloy formed from the first and second components will heat up and expand during the sintering process, melting and cracking the thin layer of the first component on the surface and forming flow marks on the surface. After a single sintering, the miscible interstitial alloy loses 4% to 8% of its weight, and the melted second component forms hollow channels near the surface of the miscible interstitial alloy. This causes the second component near the surface to continue to sweat and flow out during subsequent sintering and service, reducing the thermal conductivity and energy storage capacity of the miscible interstitial alloy.

[0023] The preferred third component of the present invention is a slurry formed by mixing silica sol, graphite and solvent, and the mass fraction of silica sol in the preferred third component is 15wt% to 20wt%. Since the sintered product of silica sol has the advantages of high structural strength and non-hygroscopicity, and the single-component layer formed by the third component is used as a protective layer for the first alloy billet, the phenomenon of cracking and overall expansion of the surface of the miscible interstitial alloy due to the melting of the second component during the high-temperature sintering process of the miscible interstitial alloy is avoided. In addition, the present invention preferably controls the viscosity of the third component to be 30mPa·s to 38m·Pas. The preferred spraying thickness of the third component of the present invention is 0.7mm to 1mm ， Ensure that a dense layer of a certain thickness is formed on the surface of the first alloy billet to hinder the melting of the second component.

[0024] S4. Pressing the second alloy billet at room temperature to form a final billet, and sintering the final billet to obtain a miscible interstitial alloy.

[0025] The second alloy billet is placed in a second mold and further pressed at room temperature to form a final billet. The preferred pressing pressure of the present invention is 8 MPa to 12 MPa, and the holding time is 5 to 10 minutes. By setting the pressure of the second alloy billet higher than that of the first alloy billet, cracking and collapse of the final billet during storage, drying, and sintering at room temperature are avoided. The diameter, length, or width of the second mold is 1.5 mm to 2 mm larger than that of the first mold.

[0026] It should be noted that the present invention places the final blank into a drying furnace for drying before high-temperature sintering. The drying temperature adopted by the present invention is 120℃~160℃, and the drying time is 300min~600min; the corresponding drying time is determined according to the size of the final blank, thereby promoting the complete volatilization of the free moisture in the final blank, and ensuring that there is no sudden increase in vapor pressure during the sintering process to cause the final blank to crack. The specific sintering process of the present invention is as follows: the dried final blank is placed in a sintering furnace, and sintered by setting a segmented sintering process. The dried final blank is first heated to an intermediate temperature at a heating rate of 3℃ / min~5℃ / min and kept warm for 40min~60min, then heated to the target temperature at a heating rate of 1℃ / min~2℃ / min and kept warm, and finally cooled to room temperature at a cooling rate of 5℃ / min~10℃ / min.

[0027] It should also be noted that during the sintering process, the intermediate sintering temperature is [0.5T m -(0~50)]℃; the target sintering temperature is [T m +(50~80)]℃, where T mis the melting point of the second component. Since graphite will oxidize and lose in air above 450°C, the sintering atmosphere is determined as follows: If the second component is a low-melting-point metal, such as Zn and Sn, it can be sintered directly in air; if the second component is a medium-to-high-melting-point metal with a melting point ≥500°C, sintering should be carried out in a vacuum, nitrogen, or inert gas atmosphere. The holding time at the target temperature varies with the shape and size of the block, and the calculation formula is shown in Formula (1): t = εH / 10 Formula (1);

[0028] In formula (1), t is the holding time for sintering at the target temperature, in hours; H is the final billet thickness, in millimeters; ε is the final billet width, B, in millimeters; and ε is a correction factor for time t. If B ≥ 2H, ε is 1.1 to 1.3. The larger the block, the longer the holding time. Furthermore, no mechanical pressure is applied during the sintering process.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] In the process of preparing a miscible interstitial alloy, the present invention uses graphite and sodium silicate as a mixed matrix, introduces silica sol, and mixes to form a first component. A metal powder is used as the second component. The first component serves as a framework, and the second component serves as a carrier, and these components are mixed to produce a blank. By optimizing the mixing method of the first component by directly mixing graphite, sodium silicate, and silica sol, the present invention avoids the conventional process of preparing the first component in a solid-liquid clay state, which requires a series of complex drying steps. This solves the problem of complex and time-consuming preparation processes for miscible interstitial alloys, and the present invention enables the preparation of miscible interstitial alloys.

[0031] In the process of preparing a miscible interstitial alloy, the present invention uses graphite and sodium silicate as a mixed matrix, and introduces silica sol to form a first component. Based on the mixed matrix, the present invention introduces silica sol, which has superior structural properties and extremely low moisture absorption after sintering, as the raw material for the first component. The addition of silica sol reduces the content of sodium silicate in the first component, thereby controlling the mass fractions of sodium silicate and silica sol in the first component and preventing the addition of large amounts of sodium silicate from affecting the thermal conductivity of the miscible interstitial alloy. Furthermore, the extremely low moisture absorption of silica sol after sintering reduces the effect of sodium silicate's susceptibility to moisture absorption in the air, preventing any impact on the skeletal structural properties of the miscible interstitial alloy. This reduces the storage cost of the miscible interstitial alloy and increases its service life.

[0032] In the process of preparing the miscible interstitial alloy, silica sol, graphite powder and water are mixed on the basis of a first alloy blank made of the first component and the second component to form a slurry, i.e., a third component. By introducing the third component, a thin layer of the third component is evenly wrapped around the outer surface of the first alloy blank as a protective layer. The sintered product of the silica sol in the third component has the advantages of high structural strength and extremely low moisture absorption after sintering. Since the sintering temperature is higher than the melting point T of the second component, the sintering temperature is 100°C. m This prevents the second component on the surface of the final billet from heating up and expanding during sintering, melting and cracking the thin layer of the first component on the surface and forming flow marks on the surface. After a single sintering cycle, the miscible interstitial alloy loses 4% to 8% of its weight. The melted second component forms hollow channels near the surface of the miscible interstitial alloy, causing the second component near the surface to continue sweating out during subsequent sintering and service, further reducing the alloy's thermal conductivity and energy storage capacity. At the same time, the introduction of the third component does not affect the excellent thermal conductivity and energy storage capacity of the miscible interstitial alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG1 is a diagram of a miscible interstitial alloy prepared in Example 1 of the present invention.

[0034] Figure 2 is a diagram of the miscible interstitial alloy made in Comparative Example 7 of the present invention; wherein, (a) is an appearance diagram of moisture absorption cracking after drying, (b) is a cross-sectional morphology diagram, (c) is an appearance diagram of the second component melted out after sintering, and (d) is an appearance diagram of the second component melted out after sintering. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings.

[0036] It should be noted that the sources of the materials of the present invention are as follows:

[0037] The graphite powder of the present invention is purchased from Shenzhen Jinda Power Technology Co., Ltd., and has a particle size of 40 μm to 60 μm.

[0038] The sodium silicate powder of the present invention is purchased from Gongyi Borun Refractory Materials Co., Ltd., with a particle size of 40 μm to 80 μm and a modulus of 3.0 to 3.4.

[0039] The silica sol of the present invention was purchased from Shandong Guohua Co., Ltd. The silica sol is a slightly milky white solution with a density of 1.28 g / cm 3 ~1.3g / cm 3 , viscosity ≤28mPas (20℃).

[0040] The metal powder of the present invention is purchased from Qinghe County Aoshuo Metal Materials Co., Ltd., and the particle size of the metal powder is 100 μm to 500 μm.

[0041] Example 1

[0042] This embodiment provides a method for preparing a miscible interstitial alloy.

[0043] S1. Graphite and sodium silicate are used as a mixed matrix, and silica sol is introduced and mixed to form a first component.

[0044] Metal powder is used as the second component.

[0045] The first component is used as a skeleton and the second component is used as a carrier, and they are mixed to prepare a blank.

[0046] 1.1) 6% sodium silicate, 1.5% silica sol, 42.5% water, and 50% graphite powder were placed in a sealed container, wherein the volume of the mixed slurry was less than 35% of the volume of the sealed container. The sealed container was placed in a three-dimensional oscillating mixer at a rotation speed of 20 rpm for 30 minutes to obtain a first component.

[0047] 1.2) 500 g of the first component and 500 g of Al metal powder were thoroughly mixed in a three-dimensional oscillating mixer at a rotation speed of 20 r / min for 300 min to obtain a blank.

[0048] S2. Place the blank into a first mold and perform pressing at room temperature with a pressing pressure of 8 MPa and a holding time of 10 min to produce a first alloy blank.

[0049] S3. Mixing silica sol, graphite powder and water to form a slurry, i.e., the third component.

[0050] The third component is used as a protective layer and sprayed on the surface of the first alloy billet to form a second alloy billet.

[0051] 3.1) Saturated silica sol and water were mixed, stirred thoroughly, and then prepared to obtain an 18 wt% silica sol aqueous solution.

[0052] 3.2) 500 g of the silica sol aqueous solution and 500 g of graphite powder were mixed uniformly, and then sufficient water was added to form a slurry. The viscosity of the slurry was controlled to be 35.0 mPas to obtain a third component.

[0053] 3.3) The third component was evenly sprayed onto the surface of the first alloy billet using a spraying machine to a thickness of 0.78 mm to produce a second alloy billet.

[0054] S4. Pressing the second alloy billet at room temperature to form a final billet, and sintering the final billet to obtain a miscible interstitial alloy.

[0055] 4.1) The second alloy billet was placed in a second mold and continued to be pressed at room temperature at a pressure of 12 MPa for 10 min to form a final billet. The diameter / length / width and height of the second mold were all 1.2 mm larger than those of the first mold.

[0056] 4.2) The final ingot was placed in a drying furnace for drying at 120°C for 300 min. The dried final ingot was then heated to 400°C at a heating rate of 3°C / min and held at that temperature for 40 min. The temperature was then increased at a heating rate of 1°C / min to a target temperature of 700°C. After holding at that temperature for 2 h, the temperature was cooled to room temperature at a cooling rate of 5°C / min to obtain a miscible interstitial alloy.

[0057] Example 2

[0058] This embodiment provides a method for preparing a miscible interstitial alloy.

[0059] S1. Graphite and sodium silicate are used as a mixed matrix, and silica sol is introduced and mixed to form a first component.

[0060] Metal powder is used as the second component.

[0061] The first component is used as a skeleton and the second component is used as a carrier, and they are mixed to prepare a blank.

[0062] 1.1) 4% sodium silicate, 1% silica sol, 44% water, and 51% graphite powder were placed in a sealed container, wherein the volume of the mixed slurry was less than 35% of the volume of the sealed container. The sealed container was placed in a three-dimensional oscillating mixer at a rotation speed of 20 rpm for 30 minutes to obtain a first component.

[0063] 1.2) 500 g of the first component and 500 g of Al metal powder were thoroughly mixed in a three-dimensional oscillating mixer at a rotation speed of 20 r / min for 300 min to obtain a blank.

[0064] S2. Place the blank into a first mold and perform pressing at room temperature with a pressing pressure of 5 MPa and a holding time of 5 min to produce a first alloy blank.

[0065] S3. Mixing silica sol, graphite powder and water to form a slurry, i.e., the third component.

[0066] The third component is used as a protective layer and sprayed on the surface of the first alloy billet to form a second alloy billet.

[0067] 3.1) Saturated silica sol and water were mixed to obtain a 15 wt% silica sol aqueous solution.

[0068] 3.2) 500 g of the silica sol aqueous solution and 500 g of graphite powder were mixed uniformly, and then sufficient water was added to form a slurry. The viscosity of the slurry was controlled to be 35.0 mPas to obtain a third component.

[0069] 3.3) The third component was evenly sprayed onto the surface of the first alloy billet using a spraying machine to a thickness of 0.78 mm to produce a second alloy billet.

[0070] S4. Pressing the second alloy billet at room temperature to form a final billet, and sintering the final billet to obtain a miscible interstitial alloy.

[0071] 4.1) The second alloy billet was placed in a second mold and continued to be pressed at room temperature at a pressure of 8 MPa and a holding time of 5 min to form a final billet. The diameter / length / width and height of the second mold were all 1.2 mm larger than those of the first mold.

[0072] 4.2) The final ingot was placed in a drying furnace for drying at 120°C for 300 min. The dried final ingot was then heated to 400°C at a heating rate of 5°C / min and held for 60 min. The temperature was then increased at a heating rate of 2°C / min to a target temperature of 700°C. After holding for 2 h, the temperature was cooled to room temperature at a cooling rate of 5°C / min to obtain a miscible interstitial alloy.

[0073] The difference between this embodiment and embodiment 1 is:

[0074] In the first component of this embodiment, sodium silicate accounts for 4% of the total mass of the first component, and silica sol accounts for 1% of the total mass of the first component.

[0075] Example 3

[0076] This embodiment provides a method for preparing a miscible interstitial alloy.

[0077] S1. Graphite and sodium silicate are used as a mixed matrix, and silica sol is introduced and mixed to form a first component.

[0078] Metal powder is used as the second component.

[0079] The first component is used as a skeleton and the second component is used as a carrier, and they are mixed to prepare a blank.

[0080] 1.1) 2% sodium silicate, 0.5% silica sol, 49.5% water, and 48% graphite powder were placed in a sealed container, wherein the volume of the mixed slurry was less than 35% of the volume of the sealed container. The sealed container was placed in a three-dimensional oscillating mixer at a rotation speed of 20 rpm for 30 minutes to obtain a first component.

[0081] 1.2) 500 g of the first component and 500 g of Al metal powder were thoroughly mixed in a three-dimensional oscillating mixer at a rotation speed of 20 r / min for 300 min to obtain a blank.

[0082] S2. Place the blank into a first mold and perform pressing at room temperature with a pressing pressure of 7 MPa and a holding time of 8 min to produce a first alloy blank.

[0083] S3. Mixing silica sol, graphite powder and water to form a slurry, i.e., the third component.

[0084] The third component is used as a protective layer and sprayed on the surface of the first alloy billet to form a second alloy billet.

[0085] 3.1) Saturated silica sol and water are mixed to obtain a 20 wt % silica sol aqueous solution.

[0086] 3.2) 500 g of the silica sol aqueous solution and 500 g of graphite powder were mixed uniformly, and then sufficient water was added to form a slurry. The viscosity of the slurry was controlled to be 35.0 mPas to obtain a third component.

[0087] 3.3) The third component was evenly sprayed onto the surface of the first alloy billet using a spraying machine to a thickness of 0.78 mm to produce a second alloy billet.

[0088] S4. Pressing the second alloy billet at room temperature to form a final billet, and sintering the final billet to obtain a miscible interstitial alloy.

[0089] 4.1) The second alloy billet was placed in a second mold and continued to be pressed at room temperature at a pressure of 8 MPa for 10 minutes to form a final billet. The diameter, length, width, and height of the second mold were all 1 mm larger than those of the first mold.

[0090] 4.2) The final ingot was placed in a drying furnace for drying at 120°C for 300 min. The dried final ingot was then heated to 400°C at a heating rate of 4°C / min and held for 50 min. The temperature was then increased at a heating rate of 1°C / min to a target temperature of 700°C. After holding for 2 h, the temperature was cooled to room temperature at a cooling rate of 5°C / min to obtain a miscible interstitial alloy.

[0091] The difference between this embodiment and embodiment 1 is:

[0092] In the first component of this embodiment, sodium silicate accounts for 2% of the total mass of the first component, and silica sol accounts for 0.5% of the total mass of the first component.

[0093] Comparative Example 1

[0094] This comparative example provides a method for preparing a miscible interstitial alloy.

[0095] 1.1) 1% sodium silicate, 49% water, and 50% graphite powder were placed in a sealed container, wherein the volume of the mixed slurry was less than 35% of the volume of the sealed container. The sealed container was placed in a three-dimensional oscillating mixer at a rotation speed of 20 rpm for 30 minutes to obtain a first component.

[0096] 1.2) 500 g of the first component and 500 g of Al metal powder were thoroughly mixed in a three-dimensional oscillating mixer at a rotation speed of 20 r / min for 300 min to obtain a blank.

[0097] 1.3) The blank was placed in a first mold and pressed at room temperature at a pressure of 8 MPa for 10 min to produce a first alloy blank.

[0098] 1.4) The first alloy billet was placed in a drying furnace and dried at 120°C for 300 min. The dried first alloy billet was then heated to 400°C at a heating rate of 3°C / min and held for 40 min. The temperature was then increased at a heating rate of 1°C / min to a target temperature of 700°C. After a holding time of 2 h, the temperature was cooled to room temperature at a cooling rate of 5°C / min to obtain a miscible interstitial alloy.

[0099] The difference between this comparative example and Example 1 is:

[0100] No third component was added in this comparative example.

[0101] Comparative Example 2

[0102] This comparative example provides a method for preparing a miscible interstitial alloy.

[0103] The difference between this comparative example and Example 1 is:

[0104] In this comparative example, no silica sol was added to the first component and the mass fraction of sodium silicate in the first component was 2.5%.

[0105] Comparative Example 3

[0106] This comparative example provides a method for preparing a miscible interstitial alloy.

[0107] The difference between this comparative example and Example 1 is:

[0108] In this comparative example, no silica sol was added to the first component and the mass fraction of sodium silicate in the first component was 5%.

[0109] Comparative Example 4

[0110] This comparative example provides a method for preparing a miscible interstitial alloy.

[0111] The difference between this comparative example and Example 1 is:

[0112] In this comparative example, no silica sol was added to the first component and the mass fraction of sodium silicate in the first component was 7.5%.

[0113] Comparative Example 5

[0114] This comparative example provides a method for preparing a miscible interstitial alloy.

[0115] The difference between this comparative example and Example 1 is:

[0116] In this comparative example, no silica sol was added to the first component and the mass fraction of sodium silicate in the first component was 10%.

[0117] Comparative Example 6

[0118] This comparative example provides a method for preparing a miscible interstitial alloy.

[0119] The difference between this comparative example and Example 1 is:

[0120] In this comparative example, no silica sol is added to the first component and the sodium silicate in the first component is saturated sodium silicate.

[0121] Comparative Example 7

[0122] This comparative example provides a method for preparing a miscible interstitial alloy.

[0123] This comparative example was prepared according to the experimental method of the prior art https: / / doi.org / 10.1016 / j.solener.2018.11.048, and the specific preparation process is as follows:

[0124] 1.1) Sodium silicate was dissolved in water to prepare a saturated sodium silicate solution with a mass fraction of 38.5%. 500 g of the saturated sodium silicate solution and 500 g of graphite powder were placed in a slurry mixer and stirred for 30 minutes to obtain a first component slurry.

[0125] 1.2) The first component slurry was manually divided into multiple slurry blocks of 10-20 mm × 10-20 mm, placed on a stainless steel mesh, air-dried for 2 h, and then placed in a high-temperature drying oven with the drying temperature set at 250°C and the drying time set at 2160 min to obtain concrete slurry blocks.

[0126] 1.3) Place the concrete slurry block into a grinding mill and grind it for 10 minutes. Then take it out and use a powder sieve to sieve out 40μm to 60μm graphite / sodium silicate concrete powder, which is the first component.

[0127] 1.4) Weigh 500 g of the first component, 50 g of water, and 500 g of the second component, place them in a three-dimensional oscillating mixer and mix them thoroughly for 30 min at a rotation speed of 20 rpm to produce a blank.

[0128] 1.5) Place the blank into the first mold and press at room temperature with a pressing pressure of 8 MPa and a holding time of 10 min to produce a final blank.

[0129] 1.6) The final ingot was placed in a drying furnace for drying at 120°C for 300 min. The dried final ingot was then heated to 400°C at a heating rate of 3°C / min and held for 40 min. The temperature was then increased at a heating rate of 1°C / min to a target temperature of 700°C. After holding for 2 h, the temperature was cooled to room temperature at a cooling rate of 5°C / min to obtain a miscible interstitial alloy.

[0130] Experimental testing

[0131] 1. Appearance analysis

[0132] The miscible interstitial alloys prepared in Examples 1 to 3 and Comparative Examples 1 to 6 were placed for 30 days and then subjected to appearance analysis. The results are shown in Table 1. The miscible interstitial alloy prepared in Example 1 was placed for 180 days and then subjected to appearance analysis. The results are shown in Figure 1.

[0133] Table 1 Appearance of the miscible interstitial alloys prepared in Examples 1 to 3 and Comparative Examples 1 to 6 after being placed for 30 days

[0134] Table 1 shows the appearance of the miscible interstitial alloys prepared in Examples 1-3 and Comparative Examples 1-6 after 30 days of storage. As can be seen from Table 1, Comparative Example 1 failed to form a miscible interstitial alloy through cold pressing; the miscible interstitial alloys prepared in Comparative Examples 2-6 all showed moisture absorption and cracking after 30 days of storage; whereas the miscible interstitial alloys prepared in Examples 1-3 showed no cracking after 30 days of storage. This indicates that the present invention, by adding silica sol to the first component and utilizing its extremely low moisture absorption after sintering, mitigates the effect of the sodium silicate in the first component's high moisture absorption in air, thereby preventing cracking in the prepared miscible interstitial alloy.

[0135] Figure 1 is the appearance of the miscible interstitial alloy prepared in Example 1 after being placed for 180 days. As can be seen from Figure 1, the miscible interstitial alloy prepared in Example 1 has no obvious moisture absorption cracking phenomenon after being placed for 180 days, and there is no leakage of the second component and surface cracking after multiple sintering. Figure 2 is the appearance of the miscible interstitial alloy prepared in Comparative Example 7; wherein, (a) is the appearance of moisture absorption cracking after drying, (b) is the cross-sectional morphology, (c) is the appearance of the second component melting after sintering, and (d) is the appearance of the second component melting out after sintering. It can be seen from Figure 2 that the miscible interstitial alloy prepared by Comparative Example 7 has obvious moisture absorption cracking, and there is melting of the second component after sintering. Compared with Comparative Example 7, that is, the miscible interstitial alloy prepared by the prior art, the miscible interstitial alloy prepared by the present invention has no obvious moisture absorption cracking phenomenon after being placed for 180 days, and there is no melting of the second component after sintering.

[0136] 2. Mechanical properties test

[0137] The present invention conducted compression tests on the miscible interstitial alloys prepared in Examples 1 to 3 and Comparative Examples 1 to 6. The compression test was conducted in accordance with the GB / T 1964-2023 standard and was measured using a 50 kN universal mechanical testing machine. The diameter of the miscible interstitial alloy was 30 mm, the height was 50 mm, and the compression rate was 1.0 mm / min. The results are shown in Table 2.

[0138] Table 2 Compressive strength of miscible interstitial alloys in Examples 1 to 3 and Comparative Examples 1 to 6

[0139] As can be seen from Table 1, except for the miscible interstitial alloy prepared in Comparative Example 1 which collapsed and could not be cold-formed, the miscible interstitial alloys prepared in Examples 1 to 3 and Comparative Examples 2 to 6 all had certain compressive strength.

[0140] 3. Thermal conductivity test

[0141] The present invention adopts the international standard ISO 22007-2 to conduct thermal conductivity tests on the miscible interstitial alloys prepared in Example 1 and Comparative Example 7. The parallel experimental tests are repeated 5 times to obtain the corresponding thermal conductivity coefficient test range, wherein the diameter of the miscible interstitial alloy is 30 mm and the thickness is 20 mm to 25 mm.

[0142] The thermal conductivity of the miscible interstitial alloy in Comparative Example 7 is 56 W / mK, and the thermal conductivity of the miscible interstitial alloy prepared in Example 1 is 61.7 W / mK to 69.3 W / mK. Compared with the miscible interstitial alloy in Comparative Example 7, the thermal conductivity of the miscible interstitial alloy prepared in the present invention is improved by 10.7% to 24.2%.

[0143] 4. Hardness test

[0144] The present invention uses a Vickers microhardness tester to measure the microhardness of the miscible interstitial alloys prepared in Example 1 and Comparative Example 7. The loading force is 0.2 kgf to 0.5 kgf. The pressure is maintained for 15 seconds after loading. The average value of 5 points is measured.

[0145] The surface hardness values ​​of the miscible interstitial alloys prepared in Example 1 and Comparative Example 7 are 4.52 HV and 2.47 HV, respectively. Compared with Comparative Example 7, the surface structural strength of the miscible interstitial alloy prepared in the present invention is greatly improved.

[0146] 5. Production cycle analysis

[0147] The present invention calculates the production cycle of the billet in the process of preparing the miscible interstitial alloy for Example 1 and Comparative Example 7, respectively. The production cycle of the billet in Comparative Example 7 is 2350 minutes; the production cycle of the billet in Example 1 is 330 minutes. Compared with Comparative Example 7, the production cycle of the billet in Example 1 is shortened by 86%. The subsequent pressing process and sintering process are the same. This shows that the production cycle used in the process of preparing the billet using the preparation method of the present invention is very short. At the same time, it avoids the complex process of preparing the first component in the prior art, solving the problem of the complex and time-consuming preparation process of the miscible interstitial alloy.

[0148] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. If these modifications and variations of the present invention fall within the scope of equivalent technology of the present invention, the present invention is also intended to include these modifications and variations.

Claims

1. A method for preparing a miscible interstitial alloy, characterized in that: The following steps are involved: Graphite and sodium silicate are used as a mixed matrix, and silica sol is introduced and mixed to form a first component; Using metal powder as the second component; The first component is used as a skeleton and the second component is used as a carrier, and the mixture is mixed to prepare a blank; pressing the billet at room temperature to form a first alloy billet; Mixing silica sol, graphite powder and water to form a slurry, i.e. the third component; The third component is used as a protective layer and sprayed on the surface of the first alloy billet to form a second alloy billet; The second alloy billet is pressed at room temperature to form a final billet, and the final billet is sintered to obtain a miscible interstitial alloy.

2. The method for preparing a miscible interstitial alloy according to claim 1, wherein: The mass fraction of sodium silicate in the first component is 2 wt % to 6 wt %.

3. The method for preparing a miscible interstitial alloy according to claim 1, wherein: The mass fraction of the silica sol in the first component is 0.5 wt% to 2.5 wt%.

4. The method for preparing a miscible interstitial alloy according to claim 1, wherein: The mass fraction of the graphite powder in the first component is 48 wt% to 51 wt%.

5. The method for preparing a miscible interstitial alloy according to claim 1, wherein: The spraying thickness of the third component is 0.7 mm to 1 mm.

6. The method for preparing a miscible interstitial alloy according to claim 1, wherein: The mass fraction of the silica sol in the third component is 15 wt% to 20 wt%, and the viscosity of the third component is controlled to be 30 mPa·s to 38 mPa·s.

7. The method for preparing a miscible interstitial alloy according to claim 1, wherein: The metal powder is one of Al, Cu, Zn, Sn and Al-Si alloy powder, and the particle size of the metal powder is 100 μm to 500 μm.

8. A miscible interstitial alloy prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the miscible interstitial alloy according to claim 8 in staggered energy storage and thermal energy transfer.

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