Phase change temperature testing method for phase change product

Abstract

The invention provides a method for testing the phase change temperature of a phase change product. The method comprises the following steps: weighing a phase change material with specified mass; clamping the phase change material between two glass plates, horizontally placing the phase change material, and continuously applying constant pressure to the phase change material to obtain a pressurized test body; according to a preset temperature gradient, placing the pressurized test body in a heating device which is set to a target temperature for several times, and carrying out heat preservation for a specified time; or, multiple pressurized test bodies are taken again, the multiple pressurized test bodies are synchronously placed in the heating devices with different target temperatures set according to the preset temperature gradient respectively, and heat preservation is conducted for the designated time; taking out the pressurized test body after keeping the temperature for a specified time, cooling to room temperature, and measuring the diameter of the phase change material to obtain diameter data of the phase change material at different temperatures. The phase change temperature is judged by utilizing the sudden change point of the diameter-temperature curve, a precise instrument is not needed, the cost is low, the operation is simple and convenient, and the problems of expensive equipment, low universality and the like in the prior art are solved.

Description

Technical Field

[0001] This application relates to the field of phase change materials, and in particular to a method for testing the phase change temperature of phase change products. Background Technology

[0002] With the development of technology, the design layout of electronic device components is becoming increasingly complex and the degree of integration is increasing. To ensure the normal operation of the equipment, heat dissipation devices are needed to effectively and promptly transfer the heat generated. Traditional thermal paste is made of silicone composite thermally conductive powder, which can meet the needs of low-power components. However, as the power of components increases, it has gradually become apparent that traditional thermal paste cannot adequately meet the heat dissipation requirements of high-end components.

[0003] Phase change products are solid materials at room temperature. They possess excellent heat transfer properties and can replace thermal paste, overcoming the drawbacks of thermal paste such as oil seepage and drying out during use. Phase change temperature is one of the key performance characteristics of phase change products, and it is currently primarily tested using Differential Scanning Calorimetry (DSC). While this method offers high accuracy, the equipment is expensive and the operation is complex, making it difficult to widely adopt in industrial production. Summary of the Invention

[0004] In view of the aforementioned problems, this application is made in order to provide a method for testing the phase transition temperature of a phase change product that overcomes or at least partially solves the aforementioned problems.

[0005] A method for testing the phase transition temperature of a phase change product includes the following steps:

[0006] Weigh out a specified mass of the phase change material;

[0007] The phase change material is clamped between two glass plates and placed horizontally, and a constant pressure is continuously applied to it to obtain a pressure test body;

[0008] The pressure test body is placed in a heating device set to the target temperature in stages according to a preset temperature gradient, and kept at the temperature for a specified time; or, multiple pressure test bodies are copied and placed in heating devices set to different target temperatures according to a preset temperature gradient, and kept at the temperature for a specified time.

[0009] After the pressure test body is kept at a specified temperature for a specified time, it is removed and cooled to room temperature. The diameter of the phase change material is then measured to obtain diameter data of the phase change material at different temperatures.

[0010] Furthermore, it also includes:

[0011] A diameter-temperature curve is plotted based on the diameter data and the corresponding temperature data, wherein the temperature point on the curve where the diameter changes abruptly is the phase transition temperature of the phase change material.

[0012] Further, the step of clamping the phase change material between two glass plates and placing it horizontally, and continuously applying a constant pressure to it to obtain a pressure test body includes:

[0013] The phase change material is placed in the central area of ​​the lower glass plate, and the upper glass plate is used to cover the phase change material.

[0014] A constant pressure is continuously applied to the top of the upper glass plate to obtain a pressure test body.

[0015] Furthermore, the step of continuously applying constant pressure to the top of the upper glass plate to obtain a pressure test body includes: placing a pressure block of a specified weight on the top of the upper glass plate to obtain a pressure test body.

[0016] Furthermore, the pressure block is a weight of a specified weight.

[0017] Further, the step of placing the pressurized test body into a heating device pre-set to the target temperature in stages according to a preset temperature gradient, and maintaining the temperature for a specified time, includes:

[0018] Based on a temperature gradient of 5℃ / time, the pressurized test body is placed in a heating device that has been heated to the target temperature in several sessions, and each session is kept at that temperature for 10 minutes.

[0019] Further, the step of repeatedly taking multiple pressure test subjects, simultaneously placing each of the multiple pressure test subjects in a heating device with different target temperatures set according to a preset temperature gradient, and maintaining the temperature for a specified time includes:

[0020] Repeat and obtain multiple identical pressure test specimens;

[0021] The temperatures of multiple heating devices are set sequentially in a 5°C temperature gradient.

[0022] Multiple pressurized test subjects are placed in multiple heating devices that have been heated to the target temperature and kept at that temperature for 10 minutes.

[0023] Furthermore, in the repeated extraction of multiple identical pressure test bodies, the identical pressure test bodies are prepared using the same two glass plates and phase change materials with the same mass, initial shape, and area.

[0024] Furthermore, the preset temperature gradient is 1°C.

[0025] This application has the following advantages:

[0026] In the embodiments of this application, a specified mass of phase change material is weighed; the phase change material is clamped between two glass plates and placed horizontally, and a constant pressure is continuously applied to it to obtain a pressure test body; the pressure test body is placed in a heating device set to a target temperature according to a preset temperature gradient in several batches, and kept at that temperature for a specified time; or, multiple pressure test bodies are repeatedly taken, and the multiple pressure test bodies are simultaneously placed in heating devices set to different target temperatures according to a preset temperature gradient, and kept at that temperature for a specified time; after being kept at that temperature for a specified time, the pressure test body is removed, cooled to room temperature, and the diameter of the phase change material is measured to obtain the diameter data of the phase change material at different temperatures. This application utilizes the rheological principle of phase change materials. By applying constant pressure and holding the material at different temperatures for a certain period of time, the mechanical deformation characteristics of the phase change material at different temperatures, i.e., the diameter change, are measured. The phase change temperature is determined by the abrupt change point of the curve. This method does not rely on thermal analysis instruments such as DSC / TG, but determines the phase change temperature based on mechanical deformation. The test results are more intuitive and overcome the technical bias of relying solely on thermal effects. The test method of this application is low-cost and easy to operate, solving the testing problem of large-size, heterogeneous phase change products, and is easy to promote and use. Attached Figure Description

[0027] To more clearly illustrate the technical solution of this application, the drawings used in the description of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart illustrating the steps of a phase change product phase change temperature testing method provided in an embodiment of this application;

[0029] Figure 2 This is a diameter-temperature curve of the test data provided in the embodiments of this application. Detailed Implementation

[0030] To make the objectives, features, and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0031] Reference Figure 1 The image shows an embodiment of this application providing a method for testing the phase transition temperature of a phase change product, comprising the following steps:

[0032] S110. Weigh out the specified mass of phase change material;

[0033] S120. The phase change material is clamped between two glass plates and placed horizontally. A constant pressure is continuously applied to it to obtain a pressure test body.

[0034] S130. According to the preset temperature gradient, the pressure test body is placed in a heating device set to the target temperature in several batches and kept at the temperature for a specified time; or, multiple pressure test bodies are copied and placed in heating devices set to different target temperatures according to the preset temperature gradient, and kept at the temperature for a specified time.

[0035] S140. After heat preservation for a specified time, the pressurized test body is removed and cooled to room temperature. The diameter of the phase change material is then measured to obtain the diameter data of the phase change material at different temperatures.

[0036] In the embodiments of this application, a specified mass of phase change material is weighed and clamped between two glass plates; the two glass plates holding the phase change material are placed horizontally and a constant pressure is continuously applied to them to obtain a pressure test body; the pressure test body is placed in a heating device set to a target temperature according to a preset temperature gradient in several batches and kept at that temperature for a specified time; or, multiple pressure test bodies are repeatedly taken and simultaneously placed in heating devices set to different target temperatures according to a preset temperature gradient and kept at that temperature for a specified time; after keeping at that temperature for a specified time, the pressure test body is removed, cooled to room temperature, and the diameter of the phase change material is measured to obtain the diameter data of the phase change material at different temperatures. This application utilizes the rheological principle of phase change materials. By applying constant pressure and holding the material at different temperatures for a certain period of time, the mechanical deformation characteristics of the phase change material at different temperatures, i.e., the diameter change, are measured. The phase change temperature is determined by the abrupt change point of the curve. This method does not rely on thermal analysis instruments such as DSC / TG, but determines the phase change temperature based on mechanical deformation. The test results are more intuitive and overcome the technical bias of relying solely on thermal effects. The test method of this application is low-cost and easy to operate, solving the testing problem of large-size, heterogeneous phase change products, and is easy to promote and use.

[0037] The following will further describe a method for testing the phase change temperature of a phase change product in this exemplary embodiment.

[0038] In this embodiment, step S110 involves weighing a specified mass of phase change material. Specifically, an electronic scale is used to accurately weigh a certain mass of phase change material. The mass is typically in the g level, directly reflecting the overall performance of sheet-like, block-like, and composite phase change products (such as phase change concrete and energy storage blocks). This overcomes the limitation of DSC, which can only test small samples in the mg level, resulting in insufficient representativeness. For example, this application can directly test thermally conductive phase change gaskets.

[0039] In this embodiment, step S120 involves clamping the phase change material between two glass plates and placing it horizontally, then continuously applying constant pressure to it to obtain a pressure test body.

[0040] Specifically, two clean glass plates are taken, serving as the lower and upper glass plates respectively. The phase change material is placed in the central area of ​​the lower glass plate, and then the upper glass plate is used to cover the phase change material, effectively clamping it between the two glass plates. A constant pressure is then continuously applied to the top of the upper glass plate to obtain a pressure test specimen. By continuously applying a constant pressure, a driving force for forced diffusion of the phase change material in its liquid state is provided, transforming the implicit phase transition state change into an explicit diameter abrupt change. Under constant pressure, the material diffuses uniformly in all directions, forming a clear phase transition characteristic signal that is easy to measure.

[0041] Understandably, the smooth surface of the glass plate ensures that the pressure is evenly distributed on the sample, avoiding localized abnormal deformation caused by uneven pressure application; moreover, the glass plate is chemically inert and does not react with the phase change material, avoiding corrosion and contamination problems that may occur with other pressure application devices.

[0042] As an example, the continuous application of constant pressure can specifically be achieved by placing a pressure block of a specified weight on top of the upper glass plate to obtain a pressure test body. The weight of the pressure block is fixed (e.g., 500g, 1000g), and constant pressure (error < ±2%) can be achieved without the need for complex pressure sensors or hydraulic devices.

[0043] Furthermore, the pressure block is a weight of a specified weight. The weight is a common laboratory consumable (cost of less than 10 yuan per piece), eliminating the need for customized pressure blocks, further reducing equipment investment, and making it suitable for small and medium-sized enterprises and on-site quality inspection scenarios.

[0044] In this embodiment, step S130 involves placing the pressure test body in a heating device set to a target temperature in stages according to a preset temperature gradient, and holding it at that temperature for a specified time; or, reproducing multiple pressure test bodies and simultaneously placing each of the multiple pressure test bodies in heating devices set to different target temperatures according to a preset temperature gradient, and holding them at that temperature for a specified time. It can be understood that the heat treatment of the pressure test body can be performed in stages or simultaneously, specifically including:

[0045] The heat treatment was performed in stages: Following a temperature gradient of 5°C per stage, the pressure test specimen was placed in a heating device preheated to the target temperature, with each stage holding the temperature for 10 minutes. Specifically, the heating device was first heated to the target temperature, and the pressure test specimen was placed inside and held for 10 minutes. Then, the pressure test specimen was removed, and the heating device was heated by 5°C and held. After cooling the pressure test specimen to room temperature for measurement, it was placed back into the heated device and held for 10 minutes. This process was repeated until multiple sets of data were obtained.

[0046] Alternatively, simultaneous heat treatment can be performed: Multiple identical pressure test specimens are copied; multiple heating devices are sequentially set to a temperature gradient of 5°C; the multiple pressure test specimens are placed in the heating devices that have been heated to the target temperature, and held at that temperature for 10 minutes. Specifically, multiple heating devices are simultaneously heated to the target temperature, with a temperature gradient of 5°C between the devices; multiple pressure test specimens are simultaneously placed into the heating devices, held at that temperature for 10 minutes, and then removed. Simultaneous testing can compress the testing time at multiple temperature points to a single holding time (10 minutes) plus cooling time, with a total time of <1.5 hours, improving efficiency by more than 50% compared to separate testing; furthermore, in separate testing, multiple heatings of the same pressure test specimen may affect the results due to thermal history (such as changes in crystallinity caused by repeated melting and solidification), while in simultaneous testing, the initial states of multiple samples are completely consistent, resulting in higher data reliability.

[0047] It should be noted that in reproducing multiple identical pressure test specimens, the identical pressure test specimens are prepared using the same two glass plates and phase change materials of the same mass, initial shape, and area. This ensures that the initial conditions of different test specimens are consistent, avoiding incomparable diameter data due to differences in equipment or samples.

[0048] Understandably, in the above steps, a 5°C temperature gradient can quickly locate the phase transition temperature range in the initial screening. A 10-minute holding time ensures that the internal temperature of the block sample (especially low thermal conductivity materials such as phase change plastics) is consistent with that of the heating device, avoiding false phase transition signals caused by insufficient heating (such as surface melting but the interior remaining solid).

[0049] Furthermore, to obtain a more accurate phase transition temperature, the temperature gradient can be set to 1℃ for multiple or parallel tests.

[0050] Furthermore, the aforementioned heating device can be an oven.

[0051] In this embodiment, after step S140, the pressure test body is removed after holding at a specified temperature for a specified time, and after cooling to room temperature, the diameter of the phase change material is measured to obtain diameter data of the phase change material at different temperatures. Specifically, in the multi-stage heat treatment process, after each heating and holding for 10 minutes, the pressure test body needs to be removed and cooled to room temperature, and its diameter is measured using a ruler or other tools. This process is repeated multiple times to obtain multiple temperature-diameter data relationships. In the simultaneous heat treatment process, multiple pressure test bodies are held at a specified temperature for a specified time, then removed and cooled to room temperature, and the diameters of multiple pressure test bodies are measured to obtain multiple temperature-diameter data relationships.

[0052] In this embodiment, the method further includes step S150: plotting a diameter-temperature curve based on the diameter data and the corresponding temperature data. The temperature point on the curve where the diameter undergoes a sudden change is the phase transition temperature of the phase change material. By plotting the diameter-temperature curve, the temperature point corresponding to the sudden change in the curve can be observed intuitively, thus quickly obtaining the phase transition temperature of the phase change material.

[0053] This application's testing method eliminates the need for expensive equipment such as DSC and TG (reducing costs by over 95%), requiring only a glass plate, a pressurizing device, and a heating device. This solves the problems of high equipment cost and difficulty in field application of existing technologies. By limiting the testing conditions through constant pressure, preset temperature gradients, and specified holding times, it ensures controllable testing conditions, avoids human error, and solves the problem of unstable results caused by the randomness of operation in traditional cooling curve methods. Regardless of whether it is organic (paraffin), inorganic (salt hydrates), or composite materials, it can reflect phase transition behavior through diameter changes, making its applicability far greater than specialized methods such as ultrasonic methods (only applicable to metals) and infrared methods (requiring transparent samples).

[0054] To further verify the technical effects of the present invention, the following description is provided in conjunction with specific embodiments and comparative examples.

[0055] Example

[0056] 1. Preparation before testing

[0057] Equipment calibration: Temperature calibration was performed on multiple ovens with an accuracy of ±1℃ to ensure that the deviation between the displayed temperature and the actual internal temperature of the oven is ≤0.5℃; the electronic scale (accuracy 0.1g) and caliper (accuracy 0.01mm) were calibrated to ensure accurate weighing and measurement data.

[0058] Sample pretreatment: Select the phase change gasket to be tested (solid at room temperature, with an estimated phase change temperature of about 45℃), and cut it into multiple samples with the same initial shape - each sample has a uniform mass of 15g and an initial shape of a circle with a diameter of 20mm (to ensure that all samples have the same initial area and mass).

[0059] Oven temperature setting: Set multiple ovens to the following target temperatures: 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 70℃ (temperature gradient of 5℃, covering a range of 20℃ before and after the estimated phase change temperature to ensure that the phase change point can be captured). After the oven temperature stabilizes (temperature fluctuation ≤ ±0.5℃) and is maintained for 10 minutes, the testing phase begins.

[0060] 2. Testing Process

[0061] Assembly of the pressure test body: Take 9 identical sets of lower glass plates (100mm×100mm×5mm) - phase change sample - upper glass plate (same as lower layer) - 1kg weight assembly; place each phase change sample in the center of the corresponding lower glass plate; cover with the upper glass plate, ensuring that the two glass plates are completely aligned without offset; place the 1kg weight stably in the center of each upper glass plate, ensuring that the weight's gravity is evenly transferred to the phase change sample.

[0062] Synchronous heating and heat preservation: Place the nine assembled pressure test bodies into an oven with a set temperature, and start the timer at the same time to keep them at the same temperature for 10 minutes.

[0063] Cooling and Diameter Measurement: After the heat preservation period, all pressurized test specimens were simultaneously removed and allowed to cool naturally to room temperature (approximately 20 minutes, until the glass plate felt cool to the touch). Then, the weights and the upper glass plate were removed, and the diameter of each phase-change sample was measured in different directions (horizontal, vertical, and two diagonal directions) using calipers. The average of four measurements was taken as the diameter data for the sample at that temperature. Specific measurement results are shown in Table 1 below.

[0064] Oven temperature ℃ 25 30 35 40 45 50 55 60 70 diameter cm 3 3.8 5.1 7.0 10.9 12.8 13.7 14.2 14.8

[0065] Based on the temperature and diameter data, plot a diameter-temperature curve, with the horizontal axis representing temperature in °C and the vertical axis representing diameter in cm. Figure 2 As shown in the curve, in the 35℃-40℃ range, the sample diameter only slowly increases from 5.1cm to 7.0cm, an increase of only 37%, indicating that the sample is still in a solid state at this time, and only undergoes slight thermal expansion due to the increase in temperature; in the 40℃-45℃ range, the sample diameter increases sharply from 7.0cm to 10.9cm, an increase of 56%, indicating that the sample has reached the phase transition temperature, changing from a solid state to a liquid state, with a significant increase in fluidity, and undergoes significant diffusion deformation under a constant pressure of 1kg weight; in the 45℃-50℃ range, the sample diameter slowly increases from 10.9cm to 12.8cm, an increase of only 17%, indicating that the sample has completely changed to a liquid state, and further heating only slightly improves fluidity, with no obvious diffusion space, and the diameter tends to stabilize.

[0066] Based on the abrupt change characteristics of the curve, the phase transition temperature of the phase transition gasket was determined to be 45℃, which is completely consistent with the designed phase transition temperature of the sample, thus verifying the accuracy of this test method.

[0067] This application requires only a glass plate (a common laboratory consumable), weights (cost < 100 RMB), and an oven (general equipment, cost < 5000 RMB). All required equipment is common or inexpensive laboratory equipment, and the total investment is far lower than that of a single DSC device. No professional training is required; operators can master the process in 5 minutes. The process is clear and requires no complex training; ordinary technicians can operate it, making it easy to promote on the production line. The test sample is a g-level product (e.g., 5-50g), directly reflecting the overall phase change behavior of the actual product (e.g., phase change wall panel, energy storage block), solving the problem that small DSC samples (mg level) cannot represent heterogeneous materials. During the phase change, the material changes from solid to liquid, and the diameter abrupt change point is clearly identifiable. No complex data analysis is needed; the phase change temperature is determined by the significant change in physical dimensions. The phenomenon is intuitive, the data repeatability is good, and the results are reliable. By adjusting the temperature gradient (e.g., 1℃), the accuracy can reach ±0.5℃, meeting most industrial needs. It is applicable to organic phase change materials, inorganic phase change materials, composite phase change materials, etc., and is especially suitable for large-size, heterogeneous products.

[0068] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0069] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0070] The above provides a detailed description of a phase change product phase change temperature testing method provided by this application. Specific examples have been used to illustrate the principle and implementation of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this application. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for testing the phase transition temperature of a phase change product, characterized in that, Includes the following steps: Weigh out a specified mass of the phase change material; The phase change material is clamped between two glass plates and placed horizontally, and a constant pressure is continuously applied to it to obtain a pressure test body; The pressure test body is placed in a heating device set to the target temperature in stages according to a preset temperature gradient, and kept at the temperature for a specified time; or, multiple pressure test bodies are copied and placed in heating devices set to different target temperatures according to a preset temperature gradient, and kept at the temperature for a specified time. After the pressure test body is kept at a specified temperature for a specified time, it is removed and cooled to room temperature. The diameter of the phase change material is then measured to obtain diameter data of the phase change material at different temperatures.

2. The method for testing the phase transition temperature of phase change products according to claim 1, characterized in that, Also includes: A diameter-temperature curve is plotted based on the diameter data and the corresponding temperature data, wherein the temperature point on the curve where the diameter changes abruptly is the phase transition temperature of the phase change material.

3. The method for testing the phase transition temperature of phase change products according to claim 2, characterized in that, The step of clamping the phase change material between two glass plates and placing it horizontally, and continuously applying constant pressure to it to obtain a pressure test body includes: The phase change material is placed in the central area of ​​the lower glass plate, and the upper glass plate is used to cover the phase change material. A constant pressure is continuously applied to the top of the upper glass plate to obtain a pressure test body.

4. The method for testing the phase transition temperature of phase change products according to claim 3, characterized in that, The step of continuously applying constant pressure to the top of the upper glass plate to obtain a pressure test body includes: placing a pressure block of a specified weight on the top of the upper glass plate to obtain a pressure test body.

5. The method for testing the phase transition temperature of phase change products according to claim 4, characterized in that, The pressure block is a weight of a specified weight.

6. The method for testing the phase transition temperature of phase change products according to claim 2, characterized in that, The steps of placing the pressurized test body into a heating device pre-set to a target temperature in stages according to a preset temperature gradient, and maintaining the temperature for a specified time, include: Based on a temperature gradient of 5℃ / time, the pressurized test body is placed in a heating device that has been heated to the target temperature in several sessions, and each session is kept at that temperature for 10 minutes.

7. The method for testing the phase transition temperature of phase change products according to claim 2, characterized in that, The step of repeatedly taking multiple pressure test subjects, simultaneously placing each of the multiple pressure test subjects in a heating device with different target temperatures set according to a preset temperature gradient, and holding them at that temperature for a specified time includes: Repeat and obtain multiple identical pressure test specimens; The temperatures of multiple heating devices are set sequentially in a 5°C temperature gradient. Multiple pressurized test subjects are placed in multiple heating devices that have been heated to the target temperature and kept at that temperature for 10 minutes.

8. The method for testing the phase transition temperature of phase change products according to claim 7, characterized in that, The repeated reproduction of multiple identical pressure test bodies is made of two identical glass plates and phase change materials with the same mass, initial shape and area.

9. The method for testing the phase transition temperature of phase change products according to claim 2, characterized in that, The preset temperature gradient is 1℃.

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