Heat storage alloy material, method for producing the same, and use thereof

Abstract

The application discloses a heat storage alloy material and a preparation method and application thereof. x The chemical composition of the heat storage alloy material is Al7SiRE x wherein RE is at least one selected from La, Ce, Y, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm and Lu; and x is the molar coefficient of RE, 0 The heat storage alloy material has high thermal conductivity, excellent cyclic thermal conductivity and oxidation resistance.

Description

Technical Field

[0001] This invention relates to a thermal storage alloy material, its preparation method, and its applications. Background Technology

[0002] With the massive consumption of non-renewable energy, the development and utilization of new energy sources has become a key research focus. Thermal energy storage systems can address the intermittency of solar energy, avoid fluctuations in power output, and improve the effective utilization rate of solar energy. Currently, aluminum-silicon alloys (Al-Si) are attracting widespread attention among metal-based phase change thermal energy storage materials due to their low price and high latent heat of phase change. The thermal conductivity of Al-Si alloys determines the heat transfer efficiency of the material during the phase change process. The higher the thermal conductivity of Al-Si alloys, the higher the internal energy transfer efficiency of the material, and the lower the risk of problems such as increased flow resistance at the solid-liquid interface and uneven melting. Al-Si alloys with high thermal conductivity can achieve more melting-solidification endothermic and exothermic cycles within the same time frame.

[0003] However, aluminum-silicon phase change thermal energy storage materials also face two problems in practical applications, affecting their efficiency and service life. Firstly, after repeated melting, solidification, and heat absorption / release cycles, the thermal properties of aluminum-silicon phase change thermal energy storage materials degrade. Secondly, the operating temperature of aluminum-silicon phase change thermal energy storage materials is approximately 600℃. This high-temperature environment significantly increases the oxidation rate of the aluminum-silicon alloy, making the oxide layer structure more porous and leading to unstable oxidation with prolonged heating time. These factors will hinder the widespread adoption of aluminum-silicon phase change thermal energy storage materials in engineering applications.

[0004] Studies have found that adding trace amounts of Er to Al-12Si, Al-14Si, and Al-16Si alloys can refine the primary Si phase in these alloys and generate Er2Al3Si2 intermetallic compounds. Adding trace amounts of Y to AlSi... 13 Cu3Ni2Mg 0.5 In the alloy, the eutectic Si phase is refined from coarse lamellar or needle-like structures to a fibrous structure, and the average secondary dendrite spacing of the alloy is reduced by 64.6% compared to the original alloy. The addition of trace amounts of Ce to the eutectic AlSi... 20 In alloys, the primary Si phase can be induced to refine from a polygonal star shape to a fine blocky structure. These studies mainly involve grain refinement of aluminum-silicon alloys with high Si content.

[0005] CN103451489A discloses a rare-earth element samarium-alloyed aluminum-silicon alloy, wherein the weight percentages of each component are: silicon 9.0-9.8%, samarium 0.05-0.4%, and the balance aluminum. After heating the Al-Si alloy in a graphite crucible to melt, samarium or an aluminum-samarium master alloy is added at 770-790°C according to the above weight percentages, and held at this temperature for 5-8 minutes. The resulting alloy melt is subjected to ultrasonic testing at an intensity of 10-38 W / cm².2 Intermittent ultrasonic treatment is performed with a total ultrasonic treatment time of 3–8 minutes, each ultrasonic session lasting 20–30 seconds, and an interval of 20–30 seconds. The alloy melt is then cooled to 720–740°C, held at that temperature for 31–180 minutes, and then solidified at a cooling rate of 40–65°C / min. This aluminum-silicon alloy has a relatively low Si content, and its purpose is to improve the mechanical properties of the resulting alloy. Furthermore, samarium has a high volatility during the smelting process, and this method requires a narrow temperature window and a complex addition procedure to introduce samarium during smelting. The high price of samarium significantly increases production costs.

[0006] CN110358950A discloses a method for modifying hypoeutectic cast aluminum-silicon alloys. The raw material formula is as follows: Si: 6.000–12.600%; Sr: 0.001–0.150%; La or RE: 0.020–0.122%; B: 0.001–0.150%, with the Sr / B mass ratio not exceeding 1.351 and the La / B or RE / B mass ratio between 1 and 5; the balance is Al. The aluminum-silicon alloy is obtained through melting, refining, degassing, feeding, and heat-holding casting processes. The modification grade is 4–6, and the modification duration is 2–3 hours. This method does not involve heat storage issues. The modifier in this method contains the relatively expensive Sr, and the ratio of Sr to B needs to be controlled.

[0007] CN114561562A discloses a method for treating AlSi7 alloy, comprising the following steps: mixing Al powder and Ti powder and pressing into a billet; pressing the billet and pure rare earth La block into molten aluminum and stirring to melt; casting to obtain an Al-Ti-La master alloy; stirring and holding the hypoeutectic AlSi7 alloy with the Al-Ti-La master alloy at a constant temperature; degassing and removing impurities from the melt; cooling the melt and casting to obtain a refined AlSi7 alloy. This method utilizes the Al-Ti-La master alloy as a modifier to treat AlSi7 alloy, thereby improving the strength and elongation of the cast Al-Si alloy and other mechanical properties. The mechanism of action is to promote the transformation of eutectic silicon into fine particles, which is essentially a refining mechanism and does not involve the heat storage problem of Al-Si alloy. Summary of the Invention

[0008] In view of this, one object of the present invention is to provide a thermal storage alloy material with high thermal conductivity, excellent cyclic thermal conductivity, and oxidation resistance. Another object of the present invention is to provide a method for preparing the above-mentioned thermal storage alloy material. A further object of the present invention is to provide the use of the above-mentioned thermal storage alloy material as a thermal storage material.

[0009] The present invention achieves the above objectives using the following technical solutions.

[0010] On the one hand, the present invention provides a heat storage alloy material with the chemical composition Al7SiRE. x ;

[0011] RE is selected from at least one of La, Ce, Y, Pr, Nd, Gd, Tb, Dy, Ho, Er, Tm, and Lu;

[0012] x is the molar coefficient of RE, 0 < x ≤ 0.2.

[0013] In the heat storage alloy material of the present invention, preferably, RE is selected from at least one of La, Ce, Y, Pr, Nd, Tb, and Dy; 0.02≤x≤0.15.

[0014] In the heat storage alloy material according to the present invention, preferably, RE is selected from at least one of La, Ce, Pr, and Nd; 0.05≤x≤0.1.

[0015] On the other hand, the present invention also provides a method for preparing the above-mentioned thermal storage alloy material, comprising the following steps:

[0016] 1) Provide alloy raw materials according to the molar ratio of Al, Si and RE; the alloy raw materials are composed of Al-Si master alloy and Al-RE master alloy, or the alloy raw materials are composed of pure aluminum, Al-Si master alloy and Al-RE master alloy;

[0017] 2) Heat the Al-Si master alloy or pure aluminum and Al-Si master alloy at 650-850℃ for 0.5-3 hours to obtain a molten master alloy; add Al-RE master alloy to the molten master alloy and heat at 600-800℃ for 10-60 minutes to obtain a heat storage alloy material.

[0018] According to the preparation method of the present invention, preferably, the mass fraction of Si in the Al-Si master alloy is 10-40 wt%.

[0019] According to the preparation method of the present invention, preferably, the mass fraction of Si in the Al-Si master alloy is 15-30 wt%.

[0020] According to the preparation method of the present invention, preferably, the mass fraction of RE in the Al-RE master alloy is 5-20 wt%.

[0021] According to the preparation method of the present invention, preferably, the mass fraction of RE in the Al-RE master alloy is 8-18 wt%.

[0022] Furthermore, the present invention also provides the use of the above-mentioned thermal storage alloy material as a phase change thermal storage material.

[0023] According to the application described in this invention, preferably, the average thermal conductivity of the heat storage alloy material at 25°C is at least 158 ​​W·m. -1 ·K -1 The average thermal diffusivity is at least 68 mm. 2 ·s -1 ;

[0024] The maximum weight gain per unit area of ​​the heat storage alloy material under 96 hours of high-temperature oxidation is 3 × 10⁻⁶. -3 g·cm -2 The oxidation rate is at most 2.5 × 10⁻⁶. -5 g·cm -2 ·h -1 .

[0025] The thermal storage alloy material of this invention has a high thermal conductivity and excellent cyclic thermal conductivity and oxidation resistance. Attached Figure Description

[0026] Figure 1 The X-ray diffraction pattern of the heat storage alloy material prepared in Comparative Example 1 of this invention is shown below.

[0027] Figure 2 The X-ray diffraction pattern of the heat storage alloy material prepared in Example 1 of this invention;

[0028] Figure 3 The image shows the X-ray diffraction pattern of the heat storage alloy material prepared in Example 2 of this invention. Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0030] The "thermal conductivity" mentioned in this invention refers to the amount of heat transferred through a 1-square-meter area in 1 second under steady-state heat transfer conditions, with a temperature difference of 1°C between the two surfaces of a 1-meter-thick material. The unit is W·m³. -1 ·K -1 .

[0031] The "thermal diffusivity" described in this invention is a measure of the rate at which a temperature disturbance at one point in an object is transmitted to another point, and its unit is mm. 2 ·s -1 .

[0032] The "isobaric specific heat capacity" mentioned in this invention refers to the amount of heat required to raise the temperature of a unit mass of a substance by 1 K under constant pressure. It is usually denoted as Cp and its unit is J·g. -1 ·K -1 .

[0033] The "latent heat of fusion" mentioned in this invention refers to the heat absorbed or released when a substance is heated to its melting point and changes from a solid state to a liquid state or from a liquid state to a solid state, and the unit is J / g.

[0034] The "oxidation rate" mentioned in this invention refers to the amount of substance oxidized per unit time, with units of g·cm⁻¹. -2 ·h -1 .

[0035] The "flash point count" mentioned in this invention refers to a point formed on the sample surface when a beam of light emitted by the laser source irradiates the sample during the testing process of the laser thermal conductivity meter.

[0036] <Thermal Storage Alloy Materials>

[0037] The thermal storage alloy material of the present invention is an alloy material containing Al and Si. This thermal storage alloy material can be used for phase change thermal storage, or for other applications. The thermal storage alloy material can exist in bulk, granular, or powder form. For thermal storage, bulk alloy is preferred.

[0038] The chemical composition of the thermal storage alloy material of this invention is Al7SiRE. x The subscript indicates the molar coefficient. x is the molar coefficient of RE. The molar ratio of Al to Si is 7:1.

[0039] According to one embodiment of the present invention, RE may be selected from at least one of La (lanthanum), Ce (cerium), Y (yttrium), Pr (praseodymium), Nd (neodymium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), and Lu (lutetium); preferably, RE is selected from at least one of La (lanthanum), Ce (cerium), Pr (praseodymium), and Nd (neodymium); more preferably, RE is selected from at least one of La (lanthanum) and Ce (cerium).

[0040] According to another embodiment of the present invention, the molar coefficient x of RE can be 0 < x ≤ 0.2; preferably 0.02 ≤ x ≤ 0.15; more preferably 0.05 ≤ x ≤ 0.1.

[0041] Controlling the rare earth element ratio within the aforementioned range is beneficial for inducing the formation of high-density short rod-shaped twins in the Al-Si alloy, thereby increasing the thermal conductivity of the heat storage alloy material and improving its heat storage performance and oxidation resistance. The relatively low rare earth element content in this invention forms submicron-level solid solutions of RE(AlSi) compounds within the alloy system, which avoids slag formation and precipitate phase problems during the smelting process, reducing overall process complexity and production costs.

[0042] <Preparation Method>

[0043] The preparation method of the above-mentioned thermal storage alloy material includes a raw material provision step and a heating step. This is described in detail below.

[0044] Providing raw materials steps

[0045] The required alloy raw materials are supplied according to the molar ratio of Al, Si and RE.

[0046] According to one embodiment of the present invention, the alloy raw material may be composed of Al-Si master alloy and Al-RE master alloy, or it may be composed of pure aluminum, Al-Si master alloy and Al-RE master alloy.

[0047] This invention can use any type of Al-Si master alloy and Al-RE alloy. It can use only Al-Si master alloy and Al-RE master alloy, or it can add pure aluminum. Preferably, this invention uses pure aluminum, Al-Si master alloy, and Al-RE master alloy. This is beneficial for improving the thermal storage performance and oxidation resistance of the thermal storage alloy material.

[0048] According to one embodiment of the present invention, the mass fraction of Si in the Al-Si master alloy can be 10-40 wt%, preferably 15-30 wt%, and more preferably 20-25 wt%.

[0049] According to another embodiment of the present invention, the mass fraction of RE in the Al-RE master alloy can be 5 to 20 wt%, preferably 8 to 18 wt%, and more preferably 10 to 15 wt%.

[0050] The pure aluminum, Al-Si master alloy, and Al-RE master alloy used in this invention can be commercially available products or prepared by existing methods, and no particular limitation is made herein. The purity of the pure aluminum, Al-Si master alloy, and Al-RE master alloy of this invention is at least industrially pure (99.9 wt%).

[0051] Heating steps

[0052] The Al-Si master alloy or pure aluminum and Al-Si master alloy are heated for the first time to obtain a molten master alloy; Al-RE master alloy is added to the molten master alloy and heated for the second time to obtain a heat storage alloy material.

[0053] According to one embodiment of the present invention, the temperature of the first heating can be 650-850°C, preferably 660-820°C, and more preferably 690-810°C.

[0054] According to another embodiment of the present invention, the first heating time can be 0.5 to 3 hours, preferably 0.8 to 2.5 hours, and more preferably 1 to 2 hours.

[0055] According to one embodiment of the present invention, the temperature of the second heating can be 600-800°C, preferably 650-720°C, and more preferably 660-700°C.

[0056] According to another embodiment of the present invention, the second heating time can be 10 to 60 minutes, preferably 15 to 50 minutes, and more preferably 20 to 40 minutes.

[0057] In the preparation of thermal storage alloy materials, the present invention involves heating twice to adjust the phase structure, which is more conducive to inducing the formation of high-density short rod-shaped twins in the thermal storage alloy materials.

[0058] This invention can employ medium-frequency casting, high-frequency arc melting, or strip casting, preferably medium-frequency casting or high-frequency arc melting, and more preferably medium-frequency casting. This is beneficial for improving the heat storage performance and oxidation resistance of the thermal storage alloy material.

[0059] During heating, the alloy raw material can be placed in a vessel, and the raw material is heated together with the vessel. The vessel can be any heating vessel known in the art, and is not particularly limited herein. For example, it can be a high-temperature resistant metal mold or crucible; preferably, it is one of a copper mold, graphite crucible, porcelain crucible, or quartz crucible; more preferably, it is one of a copper mold or graphite crucible with a diameter of Φ50mm×50mm.

[0060] A suitable heating temperature, combined with the composition of the alloy raw materials, is more conducive to inducing the formation of high-density short rod-shaped twins in the thermal storage alloy material, thereby increasing the thermal conductivity, thermal storage performance, and oxidation resistance. Simultaneously, it can shorten heating time and save production costs. Too low a temperature will reduce the fluidity of the alloy melt, inhibiting twin formation. Too high a temperature will cause the eutectic silicon size in the alloy melt to decrease, similarly inhibiting twin formation.

[0061] <Application>

[0062] The present invention also provides applications of the above-mentioned thermal storage alloy material.

[0063] In this invention, the thermal storage alloy material can be used as a phase change thermal storage material.

[0064] In this invention, the average thermal conductivity of the heat storage alloy material at 25°C is at least 158 ​​W·m. -1 ·K -1 Preferably at least 160 W·m -1 ·K -1 More preferably, 160–180 W·m -1 ·K -1 .

[0065] In this invention, the average thermal diffusivity of the heat storage alloy material at 25°C is at least 68 mm. 2 ·s -1 Preferably at least 70mm 2 ·s -1 More preferably 70-80mm 2 ·s -1 .

[0066] In this invention, the mass gain per unit area of ​​the thermal storage alloy material under 96 hours of high-temperature oxidation is at most 3 × 10⁻⁶. -3 g·cm -2 The preferred value is at most 2.5 × 10⁻⁶. -3 g·cm -2 More preferably, it is 1.5 to 2.5 × 10⁻⁶. -3 g·cm -2 The oxidation rate of the thermal storage alloy material under 96 hours of high-temperature oxidation conditions is at most 2.5 × 10⁻⁶. -5 g·cm -2 ·h -1 The preferred value is at most 2.4 × 10⁻⁶. -5 g·cm -2 ·h -1 More preferably, it is 2 to 2.4 × 10⁻⁶. -5 g·cm -2 ·h -1 .

[0067] The thermal storage alloy material of the present invention has a high thermal conductivity, excellent cyclic thermal conductivity and oxidation resistance, and is especially suitable as a thermal storage material in the 600°C high-temperature range.

[0068] <Testing Method>

[0069] Thermal cycling test method

[0070] 20g of alloy sample was weighed, and the sample surface was polished with sandpaper. The sample was then placed in an alumina crucible. To prevent oxidation during the experiment, the thermal cycling experiment was conducted in a vacuum tube furnace. According to the binary alloy phase diagram, the solidus temperature of the Al7Si alloy is 577±1℃. To ensure complete melting and solidification of the alloy, this experiment selected an upper limit melting temperature and a lower limit solidification temperature that are 67℃ higher or lower than the solidus temperature, i.e., Al7SiLa... x The thermal cycling temperature range of the alloy is 510–644℃.

[0071] The thermal cycling test procedure was set as follows: The alloy sample was first heated at 700℃ for 0.5 hours to fully melt it, then heated at 510℃ for 0.5 hours to begin the thermal cycling program. The temperature was then increased to 644℃ at a rate of 5℃ / min and heated for 0.5 hours, followed by a decrease to 510℃ at a rate of 5℃ / min and heated for half an hour. One cycle consisted of heating to 644℃ and cooling to 510℃. The thermal cycling test was performed 100 times. After 100 cycles, the alloy sample was removed from the alumina crucible and cut at its center for alloy microstructure and thermal storage performance testing.

[0072] High-temperature antioxidant test method

[0073] Before the experiment, an empty alumina crucible for holding the alloy was placed in a box furnace and heated at 600℃ for 3 hours to remove excess moisture and ensure that the weight of the alumina crucible remained unchanged. The alumina crucible was then cleaned with alcohol, and its weight was recorded after the alcohol had completely evaporated. A 20g alloy sample was weighed, its surface was polished to remove the oxide scale, and then it was weighed, and the total weight of the alloy sample and the alumina crucible was recorded.

[0074] High-temperature oxidation resistance experiments were conducted in a box-type resistance furnace, and the oxide film performance was determined using the weight gain method. An alumina crucible containing the alloy sample was placed inside the furnace. The experimental temperature was set to 700℃. Timing began after the furnace reached the set temperature, and the alloy sample was removed after heating for 24, 48, 72, and 96 hours. The alloy sample was first cooled to 470℃ in the furnace (to ensure alloy solidification and prevent spillage during crucible removal). After cooling, the alloy sample and the alumina crucible were immediately weighed and the weight recorded. Then, an isothermal oxidation kinetic curve was plotted based on the data to detect the increase in the oxide film on the alloy surface.

[0075] The following examples and other test methods in the comparative examples are described below:

[0076] XRD pattern: Detected and prepared using a D / MAX2500V X-ray diffractometer.

[0077] Thermal diffusivity and thermal conductivity: measured using a Netzsch LFA 467 laser thermal conductivity meter.

[0078] Latent heat of fusion: Detected using a STA449 F3 synchronous thermal analyzer from the German Netzsch Group.

[0079] <Ingredient Description>

[0080] Unless otherwise specified, all raw materials used in the following examples are commercially available products.

[0081] Comparative Example 1

[0082] Pure aluminum and Al-Si master alloy (Si is 20wt%) were weighted according to the molar ratio of Al and Si in the chemical composition Al7Si (i.e. Al7SiLa0).

[0083] Pure aluminum and Al-Si master alloy were placed in a graphite crucible, which was then placed in a medium-frequency induction furnace and heated at 750°C for 1 hour to obtain a heat storage alloy material with the chemical composition Al7Si.

[0084] The obtained thermal storage alloy material was subjected to X-ray diffraction analysis, and the XRD results are shown in the figure. Figure 1 .Depend on Figure 1 It can be seen that the Al phase and Si phase composition (XRD-copper target) of the thermal storage alloy material in Comparative Example 1 correspond to standard cards PDF 00-004-0787 and PDF 00-027-1402, respectively.

[0085] The obtained thermal storage alloy material was subjected to thermal cycling test, and the results are shown in Table 1; the thermal diffusivity and thermal conductivity of the thermal storage alloy material were also tested, and the results are shown in Table 2.

[0086] Table 1

[0087]

[0088] Table 2

[0089]

[0090] As shown in Tables 1 and 2, the thermal conductivity of the heat storage alloy material in Comparative Example 1, tested at room temperature (25℃), reached an average of 155.3 W·m. -1 ·K -1 The average thermal diffusivity reaches 65.9 mm. 2 ·s -1 Under 100 thermal cycles at 600℃, its latent heat of fusion decreased from 330.7 J / g to 315.2 J / g, with a loss rate of 4.68%.

[0091] The obtained thermal storage alloy material was subjected to high-temperature oxidation resistance test. The results of the oxidation weight gain per unit area are shown in Table 3, and the results of the oxidation rate are shown in Table 4.

[0092] Table 3

[0093]

[0094] Table 4

[0095]

[0096] As shown in Tables 3 and 4, the thermal storage alloy material of Comparative Example 1, under 96 hours of high-temperature oxidation conditions, exhibits a weight gain of 3.908 × 10⁻⁶ per unit area due to oxidation. -3 g·cm -2 Its oxidation rate is 4.07 × 10⁻⁶. -5 g·cm -2 ·h -1 .

[0097] Example 1

[0098] Pure aluminum, Al-Si master alloy (Si 20 wt%), and Al-La master alloy (La 10 wt%) were mixed according to the chemical composition Al7SiLa. 0.06 The molar ratio of Al, Si, and La in the mixture is used for weighting.

[0099] Pure aluminum and Al-Si master alloy were placed in a graphite crucible, which was then placed in a medium-frequency induction furnace and heated at 750°C for 1 hour to obtain a molten master alloy. An Al-La master alloy was then added to the molten master alloy, and the mixture was heated again at 680°C for 30 minutes to obtain Al7SiLa. 0.06 Thermal storage alloy materials.

[0100] The obtained thermal storage alloy material was subjected to X-ray diffraction analysis. The XRD results are shown in the figure. Figure 2 .Depend on Figure 2 As can be seen, the heat storage alloy material in this embodiment is composed of Al phase, Si phase and La (AlSi) compound phase (XRD-copper target), corresponding to standard cards PDF00-004-0787, PDF 00-027-1402 and PDF 97-060-8329-1402, respectively.

[0101] The obtained thermal storage alloy material was subjected to thermal cycling test, and the results are shown in Table 5; the thermal diffusivity and thermal conductivity of the thermal storage alloy material were also tested, and the results are shown in Table 6.

[0102] Table 5

[0103]

[0104] Table 6

[0105]

[0106]

[0107] As shown in Tables 5 and 6, the average thermal conductivity of the heat storage alloy material obtained in this embodiment, tested at room temperature (25°C), reaches 179.2 W·m.-1 ·K -1 The average thermal diffusivity reaches 70.1 mm. 2 ·s -1 Under 100 cycles of 600℃ thermal cycling, its latent heat of fusion decreased from 312.6 J / g to 304.6 J / g, with a loss rate of only 2.5%. Compared with the data of the thermal storage alloy material in Comparative Example 1, the thermal storage alloy material in this embodiment has a high thermal conductivity and excellent cyclic thermal conductivity and high-temperature thermal cycling stability.

[0108] The obtained thermal storage alloy material was subjected to high-temperature oxidation resistance test. The results of the oxidation weight gain per unit area are shown in Table 7, and the oxidation rate results are shown in Table 8.

[0109] Table 7

[0110]

[0111] Table 8

[0112]

[0113] As shown in Tables 7 and 8, the thermal storage alloy material obtained in this embodiment exhibits a weight gain of 2.285 × 10⁻⁶ per unit area under 96 hours of high-temperature oxidation. -3 g·cm -2 Its oxidation rate is 2.38 × 10⁻⁶. -5 g·cm -2 ·h -1 Compared with the data of the thermal storage alloy material in Comparative Example 1, the thermal storage alloy material in this embodiment has excellent high-temperature oxidation resistance.

[0114] Example 2

[0115] Pure aluminum, Al-Si master alloy (Si 25 wt%), and Al-La master alloy (La 15 wt%) were mixed according to the composition Al7SiLa 0.1 The molar ratio of Al, Si, and La in the mixture is used for weighting.

[0116] Pure aluminum and Al-Si master alloy were placed in a graphite crucible, which was then placed in a medium-frequency induction furnace and heated at 800°C for 2 hours to obtain a molten master alloy. An Al-La master alloy was then added to the molten master alloy, and the mixture was heated again at 700°C for 35 minutes to obtain an Al7SiLa master alloy. 0.1 Thermal storage alloy materials.

[0117] The obtained thermal storage alloy material was subjected to X-ray diffraction analysis. The XRD results are shown in the figure. Figure 3 .Depend on Figure 3As can be seen, the heat storage alloy material in this embodiment is composed of Al phase, Si phase and La (AlSi) compound phase (XRD-copper target), corresponding to standard cards PDF00-004-0787, PDF 00-027-1402 and PDF 97-060-8329-1402, respectively.

[0118] The obtained thermal storage alloy material was subjected to thermal cycling test, and the results are shown in Table 9; the thermal diffusivity and thermal conductivity of the thermal storage alloy material were also tested, and the results are shown in Table 10.

[0119] Table 9

[0120]

[0121] Table 10

[0122]

[0123]

[0124] As shown in Tables 9 and 10, the average thermal conductivity of the heat storage alloy material in this embodiment, tested at room temperature (25°C), reaches 161.6 W·m. -1 ·K -1 The average thermal diffusivity reaches 70.2 mm. 2 ·s -1 Under 100 cycles of 600℃ thermal cycling, its latent heat of fusion decreased from 331.2 J / g to 289.6 J / g, with a loss rate of only 12.5%. Compared with the data of the thermal storage alloy material in Comparative Example 1, the thermal storage alloy material in this embodiment has a high thermal conductivity and excellent cyclic thermal conductivity.

[0125] The obtained thermal storage alloy material was subjected to high-temperature oxidation resistance test. The results of the oxidation weight gain per unit area are shown in Table 11, and the results of the oxidation rate are shown in Table 12.

[0126] Table 11

[0127]

[0128] Table 12

[0129]

[0130] As shown in Tables 11 and 12, the thermal storage alloy material obtained in this embodiment has an oxidation weight gain per unit area of ​​1.931 × 10⁻⁶ under 96 hours of high-temperature oxidation. -3 g·cm -2 Its oxidation rate is 2.011 × 10⁻⁶. -5 g·cm -2 ·h -1Compared with the data of the thermal storage alloy material in Comparative Example 1, the thermal storage alloy material in this embodiment has excellent high-temperature oxidation resistance.

[0131] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A heat storage alloy material, characterized in that, Its chemical composition is Al7SiRE x ; RE is selected from at least one of La, Ce, Pr, and Nd; x is the molar coefficient of RE, 0.05≤x≤0.

1.

2. A method for preparing the heat storage alloy material according to claim 1, comprising the following steps: 1) Provide alloy raw materials according to the molar ratio of Al, Si and RE; wherein the alloy raw materials are composed of Al-Si master alloy and Al-RE master alloy, or the alloy raw materials are composed of pure aluminum, Al-Si master alloy and Al-RE master alloy; 2) Heat the Al-Si master alloy or pure aluminum and Al-Si master alloy at 650-850℃ for 0.5-3 hours to obtain a molten master alloy; add Al-RE master alloy to the molten master alloy and heat at 600-800℃ for 10-60 minutes to obtain a heat storage alloy material.

3. The preparation method according to claim 2, characterized in that, The mass fraction of Si in the Al-Si master alloy is 10 to 40 wt%.

4. The preparation method according to claim 3, characterized in that, The mass fraction of Si in the Al-Si master alloy is 15 to 30 wt%.

5. The preparation method according to claim 2, characterized in that, The mass fraction of RE in the Al-RE master alloy is 5 to 20 wt%.

6. The preparation method according to claim 5, characterized in that, The mass fraction of RE in the Al-RE master alloy is 8 to 18 wt%.

7. The use of the thermal storage alloy material of claim 1 as a phase change thermal storage material.

8. The use according to claim 7, characterized in that, The average thermal conductivity of the heat storage alloy material at 25°C is at least 158 ​​W·m. -1 ·K -1 The average thermal diffusivity is at least 68 mm. 2 ·s -1 ; The maximum weight gain per unit area of ​​the heat storage alloy material under 96 hours of high-temperature oxidation is 3 × 10⁻⁶. - 3 g·cm -2 The oxidation rate is at most 2.5 × 10⁻⁶. -5 g·cm -2 ·h -1 .

Images