Phase change material for aircraft brake disc

Abstract

The present invention discloses a phase change material for aircraft brake discs, belonging to the technical field of aircraft brake discs. The phase change material for aircraft brake discs comprises the following raw materials, by weight percentage: 1-5wt% NaCl, 1-5wt% KCl, 1-5wt% MgCl2, 10-20wt% LiF, 10-20wt% MgF2, 15-30wt% AlSi alloy, 15-30wt% AlMg alloy, 10-30wt% graphite, and 10-20wt% paraffin wax. Furthermore, the phase change material can be formed by mixing and pressing multiple solid powders, or by melting various powders at high temperatures and then casting them into a eutectic shape. The resulting phase change material has good thermal conductivity and high latent heat, making it suitable for use in aircraft brake disc manufacturing.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft brake discs, and more particularly relates to a phase change material for aircraft brake discs. Background Art

[0002] With the development of science and technology, aircraft brake systems are moving towards lightweight and miniaturization, while also meeting stringent requirements such as high load capacity and ultra-short takeoff and landing. Under the condition that the total braking energy of the aircraft remains unchanged, the brake disc is required to absorb more energy. At the same time, the miniaturization of the brake disc will inevitably lead to a reduction in the heat reservoir, causing the brake disc temperature to exceed the effective operating temperature of the anti-oxidation coating. This will increase the oxidation loss and wear rate of the brake disc, thereby reducing the performance and life of the brake disc. Phase change materials have the following characteristics: 1. High latent heat storage capacity. During the phase change process, it can absorb or release a large amount of heat with little temperature change; 2. Temperature stability. During the phase change process, the temperature of the material remains relatively constant until the phase change is complete; 3. Reversibility. The phase change process is usually reversible, and the material can be recycled multiple times. Therefore, applying phase change materials to aircraft brake discs can solve the above problems.

[0003] Phase change materials can be categorized into four types based on their physical form before and after the phase transition: solid-gas, liquid-gas, solid-solid, and solid-liquid. Phase change materials undergo only a change in physical form during the phase transition, without any temperature change. Ideal phase change materials should possess high latent heat, good reversibility, excellent thermal conductivity, rapid phase change rate, minimal volume change, stable performance, low cost, availability, safety, non-toxicity, and non-corrosiveness. Therefore, they are often used in heat storage or release environments, such as solar thermal storage devices.

[0004] Of the four types of phase change materials, the first two undergo significant volume changes during phase transitions, placing extremely stringent requirements on the structure and operating conditions of the heat storage system. Solid-solid phase change materials, on the other hand, suffer from low latent heat of phase transition, severe plasticity, and poor thermal conductivity. Consequently, research and practical application of these three types of materials are limited. Solid-liquid phase change materials, on the other hand, offer high latent heat of phase transition, minimal volume change, and a controllable process, making them the primary target of current research and application. Solid-liquid phase change materials can be broadly categorized into three types: inorganic, organic, and composite eutectics. Organic materials primarily include paraffin waxes, alcohols, and fatty acids, while inorganic materials primarily include crystalline hydrated salts, molten salts, and metals.

[0005] Most domestic records on phase change material brake discs are based on their structural design and do not involve records on the relevant preparation methods of phase change material brake discs. At the same time, existing phase change materials have a series of problems (such as poor thermal conductivity and high cost), which limit their application in the field of aircraft brake disc preparation. In addition, the phase change temperature of commonly used phase change materials is generally below 400°C, and the heat absorption capacity is limited under certain volume ratio conditions. However, the energy consumed during aircraft braking is large, and the maximum brake temperature can reach over 1000°C, which makes existing phase change materials difficult to use in the field of aircraft brakes. Summary of the Invention

[0006] The purpose of the present invention is to provide a phase change material for aircraft brake discs to solve the problems existing in the above-mentioned prior art and to achieve the preparation of high-performance phase change materials for aircraft brake discs.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] One of the technical solutions of the present invention is to provide a phase change material for aircraft brake discs, which comprises the following raw materials by weight:

[0009] NaCl 1-5wt%, KCl 1-5wt%, MgCl2 1-5wt%, LiF 10-20wt%, MgF2 10-20wt%, AlSi alloy 15-30wt%, AlMg alloy 15-30wt%, graphite 10-30wt% and paraffin wax 10-20wt%.

[0010] Preferably, in terms of weight percentage, in the AlSi alloy, Al accounts for 80-95 wt%, and Si accounts for 5-20 wt%; in the AlMg alloy, Al accounts for 90-99 wt%, and Mg accounts for 1-10 wt%.

[0011] The phase change temperature of the phase change material prepared using the above raw materials is 600-800°C, which is significantly higher than the phase change temperature of the existing phase change material below 400°C, so it has better practicality when used in the field of aircraft brakes.

[0012] The second technical solution of the present invention is to provide a method for preparing the phase change material for aircraft brake discs, comprising the following steps:

[0013] The NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are mixed according to the prescribed amounts and then pressed into shape to obtain the phase change material for aircraft brake discs.

[0014] Preferably, the NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are all added in the form of powder; the particle size of the NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin is independently 30 to 75 μm.

[0015] Preferably, the pressing pressure is 200 MPa.

[0016] The third technical solution of the present invention is to provide a method for preparing the phase change material for aircraft brake discs, comprising the following steps:

[0017] The NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are mixed and melted according to the prescribed amount, and then cooled to form a eutectic to obtain the phase change material for the aircraft brake disc.

[0018] Preferably, the NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are all added in the form of powder; the particle size of the NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin is independently 30 to 75 μm.

[0019] Preferably, the mixed melting of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin comprises: first mixing and melting AlSi alloy and AlMg alloy, then adding NaCl, KCl, MgCl2, LiF and MgF2 and mixing and melting, and finally adding graphite and mixing and melting.

[0020] The present invention can ensure uniform dispersion of metal and non-metal by controlling the order of adding each material during the mixing and melting process, which helps to improve the thermal conductivity of the material and give full play to the high thermal conductivity, specific heat and latent heat characteristics of the phase change material.

[0021] Preferably, the temperature of the mixed melt is 850° C.; and the cooling eutectic comprises: placing the molten material in a mold and air-cooling it to room temperature to complete the cooling of the eutectic.

[0022] The fourth technical solution of the present invention is to provide the application of the above-mentioned phase change material for aircraft brake discs in aircraft brake discs.

[0023] Preferably, the phase change material for aircraft brake discs further includes a packaging step before being used in aircraft brake discs; the packaging includes: packaging the phase change material for aircraft brake discs into a shell made of copper foil or paraffin high thermal conductivity metal material, and completing the sealing by precision welding.

[0024] Compared to existing phase change materials that require packaging through porous adsorption methods, microencapsulation methods, etc., the packaging method described in the present invention is simpler and can be achieved by simply encapsulating the phase change material into a shell made of copper foil or paraffin high thermal conductivity metal material through precision welding. The technical principle of the present invention is:

[0025] The present invention utilizes a powder mixture of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite, and paraffin wax to prepare a phase change material for aircraft brake discs. The material comprises organic, inorganic, and eutectic materials, thereby resolving the problems of poor thermal conductivity of existing phase change materials. Specifically, the inorganic eutectic material composed of NaCl, KCl, and MgCl2 can increase the sensible heat and specific heat of the material; the inorganic material composed of LiF and MgF2 can increase the latent heat of the material; the eutectic material composed of AlSi alloy and AlMg alloy can increase the thermal conductivity of the material; graphite, as a high-temperature resistant material, can increase the specific heat and thermal conductivity of the material; and paraffin wax, as an organic material, is an effective dispersant. The present invention utilizes the synergistic effects of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite, and paraffin wax, such as the dispersing effect of the paraffin wax, to uniformly disperse the added raw materials in the phase change material, thereby obtaining a phase change material with stable performance and significantly improving the thermal conductivity of the phase change material. The phase change temperature of the phase change material prepared using the above raw materials is 600-800°C, which is significantly higher than the phase change temperature of the existing phase change material below 400°C, thus having better practicality when used in the field of aircraft brake disc preparation.

[0026] The present invention controls the dosage of NaCl, KCl and MgCl2 to be: NaCl 1-5wt%, KCl 1-5wt%, MgCl2 1-5wt%, under which the best specific heat can be obtained.

[0027] The present invention controls the dosage of LiF and MgF2 to be: LiF 10-20wt%, MgF2 10-20wt%. Under this dosage, the best latent heat can be obtained.

[0028] The present invention controls the usage of AlSi alloy and AlMg alloy to be 15-30 wt% of AlSi alloy and 15-30 wt% of AlMg alloy, under which optimal heat conduction can be achieved.

[0029] The present invention controls the amount of graphite to be 10-30 wt %, which ensures that the graphite is better dispersed in the phase change material, plays an optimal heat conduction role, and reduces the fluidity of the material after phase change to avoid leakage.

[0030] The present invention discloses the following technical effects:

[0031] 1. The phase change material molding process of the present invention is simple and flexible. It can be made by mixing a variety of solid powders and then pressing them, or by melting various powders at high temperature and then casting them into eutectic shape.

[0032] 2. The phase-change material of the present invention differs from existing phase-change materials. It combines organic, inorganic, and eutectic materials, resolving the poor thermal conductivity and other issues inherent in existing phase-change materials. Furthermore, the raw materials used to prepare the phase-change material are readily available and low-cost, effectively reducing production costs.

[0033] 3. The phase change material of the present invention is simple and easy to encapsulate. Existing phase change materials are generally encapsulated through porous adsorption methods, microencapsulation methods, etc.; the present invention achieves phase change material encapsulation by mixing the phase change materials and then pressing them into a mold, or by melting and then casting them into a eutectic shape, and then welding and encapsulating them in a high-thermal-conductivity metal shell. DETAILED DESCRIPTION

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0036] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0037] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0038] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0039] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in this field and are not the focus of the present invention.

[0040] Unless otherwise specified, the raw materials used in the following examples and comparative examples of the present invention are all commercially available products, and the sources of the commercially available products do not affect the technical effects achieved by the present invention.

[0041] The carbon-carbon composite material used in the performance test of the present invention is provided by our company (Beijing Beimo High-Tech Friction Material Co., Ltd.), and the model is GA31687BM.

[0042] In the AlSi alloys involved in the following embodiments and comparative examples of the present invention, Al accounts for 85 wt% and Si accounts for 15 wt%; in the AlMg alloys, Al accounts for 95 wt% and Mg accounts for 5 wt%.

[0043] Unless otherwise specified, the room temperature in the following examples and comparative examples of the present invention is 25±5°C.

[0044] The thermal properties of the phase change materials in the following examples and comparative examples of the present invention were tested according to the following standards: the specific heat and latent heat were measured using a DTG-60H differential thermal / thermogravimetric analyzer in accordance with GB / T 3398.1-2009; and the thermal conductivity of the phase change material was measured using a BT2.15 thermal conductivity calorimeter in accordance with GB / T 10294-2008.

[0045] Example 1

[0046] This embodiment provides a phase change material for aircraft brake discs, specifically as follows:

[0047] The raw materials and their amounts for preparing phase change materials for aircraft brake discs are shown in Table 1.

[0048] Table 1 Raw materials and amounts used in preparing phase change materials for aircraft brake discs in Example 1

[0049]

[0050] The preparation steps are as follows:

[0051] Powders of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin were taken respectively according to the amounts specified in Table 1. The particle sizes of the above powders were 75μm, 75μm, 75μm, 35μm, 35μm, 75μm, 75μm, 30μm and 75μm, respectively. The powders were mixed and placed in a mold. The mold was pressed at a pressure of 200MPa at room temperature to obtain a phase change material for aircraft brake discs.

[0052] The thermal properties of the obtained phase change material for aircraft brake discs are shown in Table 2.

[0053] Table 2 Thermal properties of the phase change material for aircraft brake discs obtained in Example 1

[0054] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 73 780 0.9 2.2

[0055] Example 2

[0056] This embodiment provides a phase change material for aircraft brake discs, specifically as follows:

[0057] The raw materials and their amounts for preparing phase change materials for aircraft brake discs are shown in Table 3.

[0058] Table 3 Raw materials and amounts used in preparing phase change materials for aircraft brake discs in Example 2

[0059]

[0060]

[0061] The preparation steps are as follows:

[0062] Powders of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite, and paraffin were respectively prepared in the amounts specified in Table 3, wherein the particle sizes of the powders were 75 μm, 75 μm, 75 μm, 35 μm, 35 μm, 75 μm, 75 μm, 30 μm, and 75 μm, respectively. The AlSi alloy and AlMg alloy were first melted at 850° C., and then NaCl, KCl, MgCl2, LiF, and MgF2 were added and melted. Finally, graphite was added and stirred evenly. The mixed melt was poured into a mold and air-cooled to room temperature to obtain a phase change material for aircraft brake discs.

[0063] The thermal properties of the obtained phase change material for aircraft brake discs are shown in Table 4.

[0064] Table 4 Thermal properties of the phase change material for aircraft brake discs obtained in Example 2

[0065] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 65 690 1.2 2.0

[0066] Example 3

[0067] This embodiment provides a phase change material for aircraft brake discs, specifically as follows:

[0068] The raw materials and their amounts for preparing phase change materials for aircraft brake discs are shown in Table 5.

[0069] Table 5 Raw materials and amounts used in preparing phase change materials for aircraft brake discs in Example 3

[0070]

[0071] The preparation steps are as follows:

[0072] Powders of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite, and paraffin were respectively prepared in the amounts specified in Table 5, wherein the particle sizes of the powders were 75 μm, 75 μm, 75 μm, 35 μm, 35 μm, 75 μm, 75 μm, 30 μm, and 75 μm, respectively. The AlSi alloy and AlMg alloy were first melted at 850° C., and then NaCl, KCl, MgCl2, LiF, and MgF2 were added and melted. Finally, graphite was added and stirred uniformly. The mixed melt was poured into a mold and air-cooled to room temperature to obtain a phase change material for aircraft brake discs.

[0073] Example 4

[0074] This embodiment provides a phase change material for aircraft brake discs, specifically as follows:

[0075] The raw materials and their amounts for preparing phase change materials for aircraft brake discs are shown in Table 6.

[0076] Table 6 Raw materials and amounts used in preparing phase change materials for aircraft brake discs in Example 4

[0077]

[0078] The preparation steps are as follows:

[0079] Powders of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin were taken respectively in the amounts specified in Table 6. The particle sizes of the above powders were 75μm, 75μm, 75μm, 35μm, 35μm, 75μm, 75μm, 30μm and 75μm, respectively. The powders were mixed and placed in a mold. The mold was pressed at room temperature with a pressure of 200MPa to obtain a phase change material for aircraft brake discs.

[0080] Comparative Example 1

[0081] The difference from Example 1 is that the amount of MgCl2 is adjusted to 10 wt%, and the amount of MgF2 is reduced until the sum of the weight percentages of all raw materials is 100 wt%. The rest is the same as Example 1. The thermal properties of the obtained phase change material are shown in Table 7.

[0082] Table 7 Thermal properties of the phase change material obtained in Comparative Example 1

[0083] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 45 520 0.9 2.0

[0084] Comparing the thermal properties of Example 1 and Comparative Example 1 shows that the phase change material obtained in Example 1 has a greater thermal conductivity and latent heat, indicating superior thermal conductivity. It also demonstrates that adjusting the ratio of the inorganic materials MgCl2 and MgF2 significantly reduces the thermal conductivity of the phase change material.

[0085] Comparative Example 2

[0086] The difference from Example 2 is that the amount of KCl is adjusted to 10 wt %, and the amount of MgF 2 is reduced until the sum of the weight percentages of all raw materials is 100 wt %. The rest is the same as Example 2. The thermal properties of the obtained phase change material are shown in Table 8.

[0087] Table 8 Thermal properties of the phase change material obtained in Comparative Example 2

[0088] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 44 510 1.2 2.0

[0089] Comparing the thermal performance results of Example 2 and Comparative Example 2 shows that the phase change material obtained in Example 2 has a greater thermal conductivity and latent heat, indicating that it has superior thermal conductivity. It also shows that adjusting the ratio of KCl and MgF2 inorganic materials significantly reduces the thermal conductivity of the phase change material.

[0090] Comparative Example 3

[0091] The differences from Example 1 are as follows: the amount of LiF was adjusted to 35 wt %, the amount of KCl was adjusted to 1 wt %, and the amount of AlMg alloy was reduced until the sum of the weight percentages of all raw materials was 100 wt %. The rest of the process was the same as in Example 1. The thermal properties of the resulting phase change material are shown in Table 9.

[0092] Table 9 Thermal properties of the phase change material obtained in Comparative Example 3

[0093] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 22 630 1.0 2.0

[0094] Comparing the thermal performance results of Example 1 and Comparative Example 3 shows that the phase change material obtained in Example 1 has a greater thermal conductivity and latent heat, indicating superior thermal conductivity. It also demonstrates that adjusting the ratio of the LiF and MgF2 inorganic materials and the AlMg alloy eutectic material significantly reduces the thermal conductivity of the phase change material.

[0095] Comparative Example 4

[0096] The differences from Example 2 are as follows: the amount of LiF was adjusted to 35 wt %, the amount of MgCl2 was adjusted to 1 wt %, and the amount of AlMg alloy was reduced until the sum of the weight percentages of all raw materials was 100 wt %. Other conditions were the same as in Example 2. The thermal properties of the resulting phase change material are shown in Table 10.

[0097] Table 10 Thermal properties of the phase change material obtained in Comparative Example 4

[0098]

[0099]

[0100] Comparing the thermal properties of Example 2 and Comparative Example 4 shows that the phase change material obtained in Example 2 has a greater thermal conductivity and latent heat, indicating superior thermal conductivity. It also demonstrates that adjusting the ratio of the LiF and MgCl2 inorganic materials and the AlMg alloy eutectic material significantly reduces the thermal conductivity of the phase change material.

[0101] Comparative Example 5

[0102] The difference from Example 1 is that the amount of AlSi alloy is adjusted to 10 wt %, and the amount of NaCl is increased until the sum of the weight percentages of all raw materials is 100 wt %. The rest is the same as Example 1. The thermal properties of the obtained phase change material are shown in Table 11.

[0103] Table 11 Thermal properties of the phase change material obtained in Comparative Example 5

[0104] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 32 530 1.0 2.1

[0105] Comparing the thermal performance results of Example 1 and Comparative Example 5 shows that the phase change material obtained in Example 1 has a greater thermal conductivity and latent heat, indicating superior thermal conductivity. It also demonstrates that adjusting the ratio of the KCl inorganic material and the AlSi alloy eutectic material significantly reduces the thermal conductivity of the phase change material.

[0106] Comparative Example 6

[0107] The difference from Example 2 is that the amount of AlSi alloy is adjusted to 45 wt %, the amount of AlMg alloy is adjusted to 15 wt %, and the amount of MgF2 is reduced until the sum of the weight percentages of all raw materials is 100 wt %. The rest of the process is the same as in Example 2. The thermal properties of the resulting phase change material are shown in Table 12.

[0108] Table 12 Thermal properties of the phase change material obtained in Comparative Example 6

[0109] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 45 520 0.9 2.0

[0110] Comparing the thermal properties of Example 2 and Comparative Example 6 shows that the phase change material obtained in Example 2 has a greater thermal conductivity and latent heat, indicating superior thermal conductivity. It also demonstrates that adjusting the ratio of the MgF2 inorganic material and the AlSi alloy and AlMg alloy eutectic materials significantly reduces the thermal conductivity of the phase change material.

[0111] Comparative Example 7

[0112] The difference from Example 1 is that the amount of AlSi alloy is adjusted to 10 wt %, and the amount of AlMg alloy is increased until the sum of the weight percentages of all raw materials is 100 wt %. Other conditions are the same as Example 1. The thermal properties of the obtained phase change material are shown in Table 13.

[0113] Table 13 Thermal properties of the phase change material obtained in Comparative Example 7

[0114] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 48 600 1.2 2.0

[0115] Comparing the thermal properties of Example 1 and Comparative Example 7 shows that the phase change material obtained in Example 1 has a greater thermal conductivity and latent heat, indicating superior thermal conductivity. It also demonstrates that adjusting the ratio of the AlSi alloy and AlMg alloy eutectic materials significantly reduces the thermal conductivity of the phase change material.

[0116] Comparative Example 8

[0117] The difference from Example 1 is that the AlSi alloy is replaced by Al in equal amounts, and the rest is the same as Example 1. The thermal properties of the obtained phase change material are shown in Table 14.

[0118] Table 14 Thermal properties of the phase change material obtained in Comparative Example 8

[0119] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 70 510 0.9 2.0

[0120] Comparing the thermal performance results of Example 1 and Comparative Example 8, it can be seen that the latent heat of the phase change material obtained in Example 1 is greater, indicating that eutectic materials play an important role in improving the latent heat of the phase change material.

[0121] Comparative Example 9

[0122] The difference from Example 1 is that the AlMg alloy is replaced by Al in equal amounts, and the rest is the same as Example 1. The thermal properties of the obtained phase change material are shown in Table 15.

[0123] Table 15 Thermal properties of the phase change material obtained in Comparative Example 9

[0124] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 71 520 0.9 2.0

[0125] Comparing the thermal performance results of Example 1 and Comparative Example 9, it can be seen that the latent heat of the phase change material obtained in Example 1 is greater, indicating that eutectic materials play an important role in improving the latent heat of the phase change material.

[0126] Comparative Example 10

[0127] The difference from Example 1 is that equal amounts of NaCl, KCl, and MgCl2 are replaced by MgF2, and the rest are the same as Example 1. The thermal properties of the obtained phase change material are shown in Table 16.

[0128] Table 16 Thermal properties of the phase change material obtained in Comparative Example 10

[0129] Performance indicators Thermal conductivity W / (m·K) Latent heat J / g Specific heat J / (g·K) <![CDATA[Density g / cm 3 > result 60 500 0.7 2.0

[0130] By comparing the thermal performance results of Example 1 and Comparative Example 10, it can be seen that the thermal conductivity and latent heat of the phase change material obtained in Example 1 are greater, indicating that the present invention significantly improves the thermal conductivity of the obtained phase change material by selecting a specific dosage ratio and a specific type of inorganic material.

[0131] Performance testing:

[0132] The performance of the phase change materials for aircraft brake discs prepared in Examples 1 to 2 and Comparative Examples 1 to 10 was tested:

[0133] First, prepare the test specimen:

[0134] Packaging: The aircraft brake discs prepared in Examples 1 to 2 and Comparative Examples 1 to 10 were respectively encapsulated in a housing made of copper foil using a phase change material. The encapsulation volume was 20% of the volume of the inner cavity of the housing, and the housing thickness was 0.15 mm.

[0135] Filling: The encapsulated phase change material is filled into the friction and wear specimen prepared from the carbon-carbon composite material (commercially available).

[0136] Next, perform performance testing:

[0137] (1) The friction and wear performance was tested using MM3000 produced by Xi'an Shuntong Experimental Equipment Manufacturing Co., Ltd.

[0138] (2) Conduct 1:1 test comparison and verification through aircraft brake ground dynamic test bench.

[0139] The results are shown in Tables 17 and 18.

[0140] Table 17 Friction and wear properties tested by MM3000

[0141]

[0142] Table 18 Brake power bench test results

[0143]

[0144] As shown in Tables 17 and 18, the maximum braking temperature of brake discs prepared using the phase change materials described in Examples 1 and 2 is significantly lower than that of existing carbon-carbon composite materials and the phase change materials described in Comparative Examples 1 to 10. This demonstrates that the phase change materials prepared by the present invention have superior thermal conductivity and are more practical for use in the manufacture of aircraft brake discs.

[0145] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0146] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A phase change material for aircraft brake discs, characterized in that: Calculated by weight percentage, the preparation comprises the following raw materials: NaCl 1-5wt%, KCl 1-5wt%, MgCl2 1-5wt%, LiF 10-20wt%, MgF2 10-20wt%, AlSi alloy 15-30wt%, AlMg alloy 15-30wt%, graphite 10-30wt% and paraffin wax 10-20wt%; In terms of weight percentage, in the AlSi alloy, Al accounts for 80-95wt% and Si accounts for 5-20wt%; in the AlMg alloy, Al accounts for 90-99wt% and Mg accounts for 1-10wt%.

2. The method for preparing the phase change material for aircraft brake discs according to claim 1, characterized in that: The steps include: The NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are mixed according to the prescribed amounts and then pressed into shape to obtain the phase change material for aircraft brake discs.

3. The preparation method according to claim 2, characterized in that The NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are all added in the form of powder; the particle size of the NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin is independently 30 to 75 μm.

4. The preparation method according to claim 2, characterized in that The pressure of the compression molding is 200 MPa.

5. The method for preparing the phase change material for aircraft brake discs according to claim 1, characterized in that: The steps include: The NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are mixed and melted according to the prescribed amount, and then cooled to form a eutectic to obtain the phase change material for the aircraft brake disc.

6. The preparation method according to claim 5, characterized in that The NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin are all added in the form of powder; the particle size of the NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin is independently 30 to 75 μm.

7. The preparation method according to claim 5, characterized in that The mixed melting of NaCl, KCl, MgCl2, LiF, MgF2, AlSi alloy, AlMg alloy, graphite and paraffin comprises: firstly mixing and melting AlSi alloy and AlMg alloy, then adding NaCl, KCl, MgCl2, LiF and MgF2 and mixing and melting, and finally adding graphite and mixing and melting.

8. The preparation method according to claim 5, characterized in that The temperature of the mixed melt is 850° C.; and / or, the cooling eutectic comprises: placing the molten material in a mold and air-cooling it to room temperature to complete the cooling eutectic.

9. Use of the phase change material for aircraft brake discs according to claim 1 in aircraft brake discs.

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