Rheological property and heat-conducting property combined measurement method and equipment

Abstract

The invention relates to the technical field of material performance testing, and provides a rheological property and heat-conducting property combined measurement method and equipment, and the method comprises the following steps: placing a sample to be tested on a first surface of a tray; adjusting the position of the rotor unit to enable the rotating head to be close to the first surface of the tray and to be in contact with the surface of the to-be-tested sample; the heating element and the refrigerating element are started, so that the heating surface of the heating element transmits heat to the rotating head through the rotating rod and transmits the heat to the to-be-tested sample through the rotating head, and the refrigerating surface of the refrigerating element transmits cold energy to the to-be-tested sample through the tray, and the to-be-tested sample is cooled under the combined action of the heating element and the refrigerating element. The temperature of the to-be-tested sample is maintained in a preset temperature range; the rotor unit is started, so that the rotating rod drives the rotating head to rotate, and the rotating head shears and stirs the to-be-tested sample according to a preset shearing rate; and maintaining the preset shear rate, and measuring the rheological property and heat-conducting property of the sample to be measured to obtain rheological property parameters and heat-conducting property parameters.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material performance testing, in particular to a method and device for jointly measuring rheological properties and thermal conductivity. BACKGROUND

[0002] In material research and application, rheological properties and thermal conductivity are core indicators for evaluating material performance. From electronic device thermal management to polymer material processing, and to composite material preparation, the synergistic effect of rheological properties and thermal conductivity directly affects product performance. Therefore, there is an urgent practical need to jointly measure the rheological and thermal conductivity properties of materials.

[0003] However, in the related art, rheological and thermal conductivity property measurements are separate. Traditional rheological test equipment collects rheological parameters such as torque by applying shear disturbance, and it is difficult to synchronously obtain thermal conductivity data. Specifically, it is not possible to obtain real-time rheological and thermal conductivity comprehensive data of materials under the same working conditions, and it is difficult to deeply study the internal coupling relationship between the rheological behavior and thermal conductivity of materials in actual application scenarios. For example, in the processing of polymer materials, the flow state (rheological properties) of the material will affect its internal microstructure, and thus may change its thermal conduction path and thermal conduction efficiency, but the related art cannot synchronously capture these changes. Secondly, separate testing requires the preparation of multiple samples, which consumes a large amount of time, materials and labor costs. Moreover, the sample state may differ under different test conditions, which also introduces additional errors, reducing the accuracy and reliability of the test results. For thermal conductivity testing, due to the temperature and stress state of low thermal resistance liquid metal composites, the sample may stick, remain, or even solidify or bond during testing, resulting in loss or contamination during transfer, especially for high-viscosity and easily-deformed composites. Even some materials may solidify or bond during testing, making it difficult to remove the sample, and some low thermal resistance liquid metal composites are difficult to remove from the thermal resistance meter test interface due to their strong adhesion, which may damage the test surface after being forcibly removed. The traditional thermal resistance meter cannot replace the contact interface between the hot end and the cold end, so it may affect the accuracy and precision of subsequent test results. SUMMARY

[0004] In view of the above problems, the present application provides a method and device for jointly measuring rheological properties and thermal conductivity.

[0005] The application provides a method for jointly measuring rheological properties and thermal conductivity properties, comprising: placing a sample to be measured on a first surface of a tray; adjusting the position of a rotor unit so that a rotor head is close to the first surface of the tray and in contact with the surface of the sample to be measured; turning on a heating element and a refrigeration element, so that the heating surface of the heating element transmits heat to the rotor head through a rotating rod and to the sample to be measured through the rotor head, and the refrigeration surface of the refrigeration element transmits cold to the sample to be measured through the tray, so that the temperature of the sample to be measured is maintained within a predetermined temperature range under the joint action of the heating element and the refrigeration element; starting the rotor unit so that the rotating rod drives the rotor head to rotate, so that the rotor head shears and stirs the sample to be measured at a preset shear rate; maintaining the preset shear rate, measuring the rheological properties and thermal conductivity properties of the sample to be measured, and obtaining rheological property parameters and thermal conductivity property parameters.

[0006] According to an embodiment of the application, the method further comprises: based on the rheological property parameters and the thermal conductivity property parameters, performing correlation calculation according to a target model to determine the correlation of the sample to be measured at the preset shear rate; and generating a performance control scheme for the sample to be measured according to the correlation, the performance control scheme including a target shear rate, a target temperature difference or a target ratio that need to be reached for the sample to be measured to meet the preset performance requirements.

[0007] According to an embodiment of the application, the target ratio includes the mass ratio, the volume ratio or the particle size distribution ratio of a base material to a functional filler in the sample to be measured, and the functional filler is an additive that affects the rheological properties or the thermal conductivity properties of the sample to be measured.

[0008] According to an embodiment of the application, the target model is obtained according to the following steps: obtaining a plurality of historical samples; collecting a plurality of groups of historical rheological property parameters and historical thermal conductivity property parameters corresponding to the plurality of historical samples under a preset shear rate; and substituting the historical rheological property parameters and the historical thermal conductivity property parameters into an initial model to iteratively optimize the empirical constants and the power-law exponents in the initial model, thereby obtaining the target model.

[0009] According to an embodiment of the application, the initial model includes a first model and a second model, the first model includes a yield stress, a pressure and a shear modulus, and is used to represent the change rule of the rheological properties of the sample to be measured with an external load, and the second model includes a thermal conductivity coefficient and a contact thickness, and is used to represent the change rule of the thermal conductivity properties of the sample to be measured with an interface state, and the initial model is:

[0010]

[0011] wherein BLT is used to represent the contact thickness actually participating in heat conduction of the sample to be measured under the action of shear and pressure; is the thermal conductivity coefficient of the sample to be measured; is the total thermal resistance; 、 is an empirical constant; thermal conductivity of the base material; is a yield stress; P is a pressure; G is a shear modulus; m, n are power law exponents; is a surface roughness of the sample to be measured.

[0012] According to the embodiment of the present application, the rheological property parameter at least includes the thickness of the sample to be measured, the thermal conductivity property parameter at least includes the heat flux flowing through the sample to be measured and the thermal conductivity, thermal resistance of the sample to be measured, the rheological property and the thermal conductivity property of the sample to be measured are measured to obtain the rheological property parameter and the thermal conductivity property parameter, comprising: obtaining the torque data, the angular velocity, the pressure data and the plurality of temperature data fed back by the sample to be measured; calculating the thickness of the sample to be measured according to the preset shear rate, the torque data and the pressure data; calculating the heat flux flowing through the sample to be measured according to the plurality of temperature data and the preset temperature difference, wherein the preset temperature difference is the temperature difference between the heating element and the refrigeration element; and calculating the thermal conductivity of the sample to be measured according to the heat flux flowing through the sample to be measured and the preset temperature difference.

[0013] According to the embodiment of the present application, the thickness of the sample to be measured is calculated according to the preset shear rate, the torque data and the pressure data, comprising: calculating the viscosity of the sample to be measured according to the preset shear rate and the torque data; calculating the yield stress of the sample to be measured according to the viscosity and the preset shear rate; and calculating the thickness of the sample to be measured according to the yield stress and the pressure data.

[0014] According to the embodiment of the present application, the plurality of temperature data includes: a first temperature value of the rotor and a second temperature value of the tray; the heat flux flowing through the sample to be measured is calculated according to the plurality of temperature data and the preset temperature difference, comprising: calculating a first temperature difference according to the first temperature value and the preset temperature value of the heating element; calculating a second temperature difference according to the second temperature value and the preset temperature value of the refrigeration element; and calculating the heat flux flowing through the sample to be measured according to the first temperature difference, the second temperature difference and the heat transfer area.

[0015] The present application provides a system for jointly measuring rheological property and thermal conductivity property, comprising: a tray, comprising a first surface and a second surface, the first surface is used for containing a sample to be measured; a rotor unit, comprising a rotating rod and a rotor, the rotating rod comprises a first end and a second end, the first end is connected with the rotor, wherein, when the rotor unit is in a working state, the rotor is in a rotating state to shear and stir the sample to be measured in the tray; a heating element, comprising a heating surface; a refrigeration element, comprising a refrigeration surface; wherein, the first end of the rotating rod is connected with the heating surface in a surface contact manner, so that the heat of the heating surface is transmitted to the rotor through the rotating rod, and then transmitted to the sample to be measured through the rotor; the second surface of the tray is connected with the refrigeration surface in a surface contact manner, so that the cold of the refrigeration surface is transmitted to the sample to be measured through the tray.

[0016] According to an embodiment of the present invention, the combined measuring device further includes: a torque sensor disposed between the rotor unit and the heating element for detecting torque data fed back by the sample to be tested; a true displacement sensor disposed on the upper part of the rotor unit for measuring the thickness of the sample to be tested; a plurality of thermocouples, wherein a first set of thermocouples is disposed on the rotor head; a second set of thermocouples is disposed on the tray; and a pressure sensor disposed between the tray and the cooling element for detecting pressure data fed back by the sample to be tested.

[0017] According to embodiments of the present invention, by performing in-situ synchronous measurements of the rheological and thermal conductivity properties of the sample under test, errors arising from traditional separate measurement methods can be minimized. Throughout the measurement process, the sample under test remains in a completely consistent physical environment. Specifically, the sample under test is always placed on the same tray, within the same temperature field constructed by the heating and cooling elements, and subjected to the same shearing state applied by the rotor unit. On the one hand, this avoids potential changes in the physical state of the sample under test during transfer, such as temperature fluctuations, accidental damage to the microstructure, or losses and contamination caused by sample adhesion. On the other hand, it avoids the critical drawback of traditional separate measurements where rheological and thermal conductivity parameters originate from different test conditions, ensuring that the acquired rheological and thermal conductivity parameters correspond to the actual state of the sample under test at the same moment. This provides a data basis for the correlation analysis of the two properties and guarantees the authenticity and accuracy of the test data. Attached Figure Description

[0018] Figure 1 A schematic diagram of the structure of the combined measuring device according to an embodiment of the present invention is shown.

[0019] Figure 2 A schematic diagram of the structure of a combined measuring device according to another embodiment of the present invention is shown.

[0020] Figure 3 A flowchart illustrating a method for jointly measuring rheological and thermal conductivity properties according to an embodiment of the present invention is shown.

[0021] Figure 4 A flowchart illustrating a method for jointly measuring rheological and thermal conductivity properties according to another embodiment of the present invention is shown.

[0022] The meanings of the reference numerals in the above figures are as follows:

[0023] 10. Pallet

[0024] 20. Rotor Unit

[0025] 210. Rotating rod; 220. Rotating head

[0026] 30. Heating element

[0027] 310. Heating surface

[0028] 40. Refrigeration components

[0029] 410. Refrigeration surface

[0030] 50. Sample to be tested

[0031] 60. Torque sensor

[0032] 70. First set of thermocouples

[0033] 80. The second group of thermocouples

[0034] 90. Pressure sensor Detailed Implementation

[0035] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the invention for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. Terms such as include, comprise, etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

[0037] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0038] In related technologies, single-performance measurement modes have shortcomings. From the perspective of physical environment and operating conditions, rheological property measurements usually need to be carried out under specific shear rates and pressure conditions, while thermal conductivity measurements rely on a stable temperature gradient and heat flow environment. The equipment parameters and environmental control requirements for the two tests differ significantly, resulting in completely different physical states of the same material in different tests. The measured data is difficult to reflect the coupling effect of the two properties in practical applications. On the other hand, when measuring separately, the sample to be measured must first undergo shear and other rheological tests in a rheometer before being transferred to a thermal resistance meter for thermal conductivity measurements, or first undergo thermal conductivity and thermal resistance tests in a thermal resistance meter before being transferred to a rheometer for rheological property measurements. The above process not only changes the temperature and stress state of the sample due to equipment conversion, but may also cause loss or contamination during transfer due to sample adhesion and residue during rheological testing. In some cases, the sample may be too viscous to be removed from the thermal resistance meter test interface, affecting both test accuracy and test efficiency, especially for high-viscosity and easily deformable composite materials. Furthermore, some materials may solidify or bond during testing. Traditional thermal resistance meters cannot handle frequent changes to the hot and cold end contact interfaces, leading to sample removal issues or damage to the test surface if forcibly removed, affecting the results and accuracy of subsequent tests. In contrast, the tray or rotor on the combined measuring device in this application is detachable and replaceable. For samples that may solidify or bond, only the tray or rotor needs to be replaced, allowing for repeated long-term testing without damaging the equipment.

[0039] Based on this, embodiments of the present invention provide a measuring device capable of jointly measuring the rheological properties and thermal conductivity of a sample.

[0040] Figure 1 A schematic diagram of the structure of the combined measuring device according to an embodiment of the present invention is shown.

[0041] like Figure 1 As shown, the combined measuring device 100 includes: a tray 10, including a first surface and a second surface, the first surface being used to hold the sample 50 to be tested; a rotor unit 20, including a rotating rod 210 and a rotating head 220, the rotating rod 210 including a first end and a second end, the first end being connected to the rotating head 220, wherein when the rotor unit 20 is in the working state, the rotating head 220 is in the rotating state to shear and stir the sample 50 to be tested in the tray 10; a heating element 30, including a heating surface 310; and a cooling element 40, including a cooling surface 410; wherein the first end of the rotating rod 210 is connected to the heating surface 310 by surface contact, so that the heat of the heating surface 310 is transferred to the rotating head 220 through the rotating rod 210, and then transferred to the sample 50 to be tested through the rotating head 220; the second surface of the tray 10 is connected to the cooling surface 410 by surface contact, so that the cold energy of the cooling surface 410 is transferred to the sample 50 to be tested through the tray 10.

[0042] According to an embodiment of the present invention, the tray can be made of copper with a thickness of 5-8 mm and a bearing area of ​​a circular region with a diameter of 10-50 mm; the rotating rod can be made of copper with a high thermal conductivity and a diameter of 8 mm; the rotating head can be made of copper with a diameter of 5-50 mm and a thickness of 5-8 mm, and the surface roughness in contact with the low thermal resistance liquid metal composite material is... ≤0.8 The diameter of the rotating head is the same as the diameter of the tray. The first end of the rotating rod needs to apply a contact pressure of 5-10N to the surface of the heating surface, and the contact flatness should be within 0.01mm / m; the second surface of the tray should also meet the above contact pressure and flatness requirements when contacting the surface of the cooling surface.

[0043] According to embodiments of the present invention, this combined measurement device, through the coordinated design of heating elements, cooling elements, rotor units, and a tray, enables the sample under test to simultaneously withstand shear forces and temperature gradients within the same test space. This avoids the traditional separate measurement operation of "transferring the sample to a thermal conductivity testing device after rheological testing." Furthermore, compared to the limitations of single-performance testing, which can only simulate local conditions, this device simultaneously measures rheological and thermal conductivity properties in situ under the same conditions. The measured data more closely reflects real-world usage scenarios, ensuring that the measurements of rheological and thermal conductivity properties are based on identical sample conditions and measurement conditions. This avoids the problem of poor data correlation caused by environmental changes during separate measurements, making the analysis of the coupling relationship between the two properties more accurate. On the other hand, it also avoids problems such as residue, adhesion, and structural damage caused by sample transfer. Simultaneously, the contact-type heat transfer design between the rotor and the tray reduces heat transfer loss, ensures temperature control accuracy, and further improves test repeatability and reliability.

[0044] Figure 2 A schematic diagram of the structure of a combined measuring device according to another embodiment of the present invention is shown.

[0045] like Figure 2 As shown, the measuring device 200 also includes: a torque sensor 60, configured between the rotor unit 20 and the heating element 30, used to detect torque data fed back by the low thermal resistance liquid metal composite material 50; the torque sensor 60 has a measurement range of 0-10 N·m and an accuracy of ±0.5%; the pressure sensor has a measurement range of 0-50 N and an accuracy of ±1%. Multiple sets of thermocouples are included, wherein the first set of thermocouples 70 is configured on the rotor head 220, and may contain four thermocouples. The installation method can be a side-mounted type, with three thermocouples located at 120°C positions on the outer periphery of the rotor head. The thermocouple surfaces are on the same plane as the lower surface of the rotor head, and the measured temperature is... The average value is The fourth installation method is recessed installation, located at the center of the rotating head, with a depth of 1mm; the second group of thermocouples 80 is configured on the tray 10, containing a total of 4, and can be installed by side-mounting, with 3 of them located at 120°C positions around the outer edge of the tray, the thermocouple surfaces being on the same plane as the upper surface of the tray, and the measured temperature being... The average value is The fourth installation method is embedded installation, located at the center of the tray, with a depth of 1mm; the pressure sensor 90 is configured between the tray 10 and the cooling element 40 to detect the pressure data fed back by the low thermal resistance liquid metal composite material 50.

[0046] According to an embodiment of the present invention, the measuring device may further include a real displacement sensor, which is configured on the upper part of the rotor unit for measuring the thickness of the low thermal resistance liquid metal composite material.

[0047] According to an embodiment of the present invention, the tray and rotor unit are surrounded by a cylindrical sealed cavity tightly fitted to their outer periphery. This cavity can be made of a high-temperature resistant, low-thermal-conductivity polyetheretherketone (PEEK) material to reduce interference from the external environment on the test. The rotor unit can rotate normally.

[0048] According to embodiments of the present invention, various sensors are used for simultaneous multi-parameter acquisition, providing data support for the performance correlation analysis of the sample under test. The synergistic effect of these sensors allows the device to simultaneously acquire multi-dimensional data related to rheology and thermal conductivity within the same test cycle, avoiding correlation errors caused by "asynchronous parameter acquisition" in traditional separate measurements. Since all sensors are integrated into the same measurement system and are in the same physical environment as the sample, the dynamic changes in sample performance during the testing process can be tracked in real time. For samples with high viscosity, easy adhesion, and sensitive structures, the transfer operation during traditional separate measurements can easily damage the sample structure, leading to distorted test data. However, this device achieves "in-situ synchronous testing" through integrated sensors, completing multi-parameter acquisition without sample transfer. It effectively preserves the original structural state of the sample under shear and temperature effects, making it particularly suitable for studying the performance coupling laws of complex samples under composite conditions. For example, it can accurately analyze the dynamic correlation between the filler distribution state and thermal conductivity of filler-type composite materials during shear dispersion, providing a more reliable test basis for material formulation optimization.

[0049] Many materials need to simultaneously meet requirements for mechanical stability and thermal conductivity / insulation. The quantitative relationship between these two factors allows for targeted research and development. For example, in thermal insulation materials, it's crucial to determine the external force (corresponding to yield stress) under which the material structure will not break down while maintaining acceptable thermal resistance, thus preventing the development of products with poor mechanical properties or inadequate insulation. Similarly, electronic packaging materials need to balance resistance to deformation (yield stress) with heat dissipation efficiency (thermal resistance) to prevent chip overheating due to excessively high thermal resistance or packaging deformation due to insufficient yield stress.

[0050] In production processes involving high temperatures and high pressures, this relationship helps determine safe and efficient process parameters. For example, in polymer injection molding, this relationship can be used to determine whether the material's thermal resistance at a specific temperature will lead to localized overheating, thereby reducing the yield stress and causing product cracking, thus allowing for adjustments to the injection temperature and pressure. Similarly, in food processing, for sauces and gels, it's necessary to determine whether the thermal resistance is sufficient to prevent spoilage under external forces during transportation and storage (not exceeding the yield stress), guiding formula adjustments during production.

[0051] For equipment subjected to long-term temperature changes and external forces, the relationship between these factors is crucial for assessing its service life and safety limits. For example, in pipe insulation, it's necessary to calculate whether external forces such as pipe vibration and external compression approach the yield stress of the insulation material, and whether the thermal resistance will increase due to slight material deformation, leading to heat loss or condensation corrosion, thus enabling the development of a maintenance plan in advance. Similarly, for building exterior wall insulation systems, it's essential to determine whether the thermal resistance can meet building energy efficiency standards long-term, assuming the insulation layer does not yield under external forces such as wind pressure and earthquakes, to avoid safety hazards and excessive energy consumption.

[0052] Figure 3 A flowchart illustrating a method for jointly measuring rheological and thermal conductivity properties according to an embodiment of the present invention is shown schematically. The following is in conjunction with... Figure 1 , Figure 2 and Figure 3 The measurement method will be explained in detail.

[0053] like Figure 3 As shown, the method for jointly measuring rheological properties and thermal conductivity includes steps S310 to S350.

[0054] Step S310: Place the sample 50 to be tested on the first surface of the tray.

[0055] According to embodiments of the present invention, the sample to be tested can be a core-reinforced liquid metal material, which is used to manufacture flexible electronic materials, such as conductive circuits for wearable devices; thermal management, such as high-efficiency heat dissipation materials; flexible robot drive components, etc., which utilize the flexibility and functionality of liquid metal, and adapt to more complex mechanical environments through core reinforcement.

[0056] According to embodiments of the present invention, such as Figure 1 As shown, the sample to be tested 50 is first placed on the first surface of the tray 10, and the sample to be tested is evenly distributed. The first surface is the bearing surface of the sample to be tested 50.

[0057] Step S320: Adjust the position of the rotor unit 20 so that the rotor head 220 approaches the first surface of the tray 10 and contacts the surface of the sample 50 to be tested.

[0058] According to an embodiment of the present invention, the position of the rotor unit 20 is adjusted so that the rotor head 220 descends to contact the surface of the sample 50 to be tested. By controlling the initial contact state between the rotor head 220 and the sample 50, the repeatability of the test is ensured, such as avoiding unstable shear force transmission due to excessively loose contact, or excessively tight contact leading to excessive initial compression deformation of the sample. Specifically, when adjusting the position of the rotor unit 20, the contact pressure needs to be controlled within 2-3 N, with an adjustment accuracy of ±0.01 mm.

[0059] In step S330, the heating element 30 and the cooling element 40 are turned on so that the heating surface 310 of the heating element transfers heat to the rotating head 220 through the rotating rod 210, and then to the sample 50 to be tested through the rotating head 220. The cooling surface 410 of the cooling element transfers cold energy to the sample 50 to be tested through the tray 10. This ensures that the temperature of the sample 50 to be tested is maintained within a predetermined temperature range under the combined action of the heating element 30 and the cooling element 40. The predetermined temperature range is a temperature range set according to the application scenario of the sample to be tested.

[0060] According to embodiments of the present invention, the heating element 30 and the cooling element 40 can be Peltier elements or other elements capable of providing heat and cold energy. Driven by a DC power supply, the Peltier element can achieve rapid and precise temperature regulation within a range of -20°C to 200°C, with an accuracy controlled within ±0.1°C. The heating element 30 and the cooling element 40 work together through a temperature control system to maintain a predetermined temperature difference across the sample under test.

[0061] According to an embodiment of the present invention, after the heating element 30 and the cooling element 40 are turned on, as... Figure 1As shown, two temperature transmission paths are formed: one provides heat to the sample 50 under test via the heating surface 310, rotating rod 210, and rotating head 220; the other provides cooling to the tray 10 via the cooling surface 410. In the first transmission path, heat is transferred from the rotating head 220 to the upper surface of the sample 50 under test; in the second transmission path, cooling is transferred from the tray 10 to the lower surface of the sample 50 under test. This creates a stable temperature gradient within the sample 50 under test. By adjusting the temperatures of the heating element 30 and the cooling element 40, this temperature field is maintained, ensuring that the sample 50 under test is within a preset temperature range, thus ensuring that the thermal conductivity measurement is performed under the target temperature conditions. The preset temperature range can simulate the temperature environment during the operation of electronic devices and can be set based on historical experience.

[0062] Step S340: Turn on the rotor unit 20 so that the rotating rod 210 drives the rotating head 220 to rotate, so that the rotating head 220 can shear and stir the sample 50 to be tested according to the preset shear rate.

[0063] According to an embodiment of the present invention, the rotor unit 20 drives the rotor head 220 to rotate at a preset shear rate, applying continuous shear perturbation to the sample 50 to be tested. The preset shear rate refers to a shear rate value pre-set according to the type of sample to be tested, and its range is [range missing]. .

[0064] In step S350, while maintaining the preset shear rate, the rheological properties and thermal conductivity of the sample 50 are measured to obtain the rheological property parameters and thermal conductivity parameters.

[0065] According to an embodiment of the present invention, the reaction torque of the sample on the rotor 220 is detected by a torque sensor, and the viscosity, yield stress, etc. are calculated in combination with the shear rate and rotor size; the pressure data of the sample is obtained by a pressure sensor 90, and the thickness change of the sample under test is estimated. The temperature of the upper and lower interfaces of the sample is measured by thermocouples on the rotor 220 and the tray 10, and the thermal conductivity, thermal resistance, etc. are calculated in combination with the heat flux.

[0066] According to embodiments of the present invention, by performing in-situ synchronous measurements of the rheological and thermal conductivity properties of the sample under test, errors generated by traditional separate measurement methods can be minimized. Throughout the entire measurement process, the sample under test remains in a completely consistent physical environment. Specifically, the sample under test is always placed on the same tray, within the same temperature field constructed by the heating and cooling elements, and is always subjected to the same shear state applied by the rotor unit. On the one hand, this avoids potential changes in the physical state of the sample under test during transfer, such as temperature fluctuations, accidental damage to the microstructure, or losses and contamination caused by sample adhesion. On the other hand, it avoids the critical drawback of traditional separate measurements where rheological and thermal conductivity parameters originate from different test conditions, ensuring that the acquired rheological and thermal conductivity parameters correspond to the actual state of the sample at the same moment. This provides a data basis for the correlation analysis of the two properties and guarantees the authenticity and accuracy of the test data.

[0067] According to an embodiment of the present invention, the rheological performance parameters include at least the thickness of the sample to be tested, and the thermal conductivity parameters include at least the heat flux flowing through the sample to be tested and the thermal conductivity of the sample to be tested.

[0068] Figure 4 A flowchart illustrating a method for jointly measuring rheological and thermal conductivity properties according to another embodiment of the present invention is shown.

[0069] like Figure 4 As shown, the rheological properties and thermal conductivity of the sample to be tested are measured to obtain the rheological property parameters and thermal conductivity parameters, including steps S410 to S440.

[0070] Step 410: Obtain torque data, pressure data, and multiple temperature data from the sample under test.

[0071] According to an embodiment of the present invention, torque data is detected by torque sensor 60 and is used to characterize the resistance of the sample under test to the rotation of the rotor; pressure data is detected by pressure sensor 90 and is used to characterize the reaction force of the sample under test on the tray under shear and temperature action; multiple temperature data are collected by thermocouples, including the temperature of the interface between the rotor and the sample under test and the temperature of the interface between the tray and the sample under test.

[0072] Step 420: Calculate the thickness of the sample to be tested based on the preset shear rate, torque data, and pressure data. This includes three calculation steps.

[0073] First, the viscosity of the sample to be tested is calculated based on the preset shear rate and torque data.

[0074] Second, the yield stress of the sample to be tested is calculated based on the viscosity and the preset shear rate.

[0075] Third, the thickness of the sample to be tested is calculated based on the yield stress and pressure data.

[0076] According to an embodiment of the present invention, in a shear rheological test, when the rotor shears the sample under test at a preset shear rate, the sample under test will generate resistance to the rotor. The torque data reflects this resistance, while viscosity, as the sample's ability to resist shear deformation, can be derived from the relationship between shear stress and shear rate, wherein the shear stress can be calculated from the torque data.

[0077] The yield stress of the sample under test can be obtained by measuring the stress-strain curve or the storage modulus-loss modulus curve using a rheometer. .

[0078] According to an embodiment of the present invention, the thickness of the sample to be tested is calculated based on the yield stress and pressure data, specifically referring to formula (1).

[0079] Formula (1)

[0080] in, The thickness of the sample to be tested. This is an empirical constant, with a value range of 10. -5 -1; P represents pressure data, and m represents the power law exponent, ranging from 0.01 to 1. The thickness of the sample is measured using a real displacement sensor in the rheometer, and C1 and m are obtained through fitting.

[0081] Step 430: Calculate the heat flux flowing through the sample under test based on multiple temperature data and a preset temperature difference. The preset temperature difference is the temperature difference between the heating element and the cooling element. The preset temperature difference is set according to the actual application conditions of the sample under test and ranges from 0.01 to 150℃.

[0082] According to embodiments of the present invention, such as Figure 2 As shown, multiple temperature data include: the first temperature value of the rotor obtained by the first set of thermocouples. The second temperature value of the tray was obtained by measuring the second set of thermocouples. .

[0083] The heat flux flowing through the sample is calculated based on multiple temperature data and a preset temperature difference, including three calculation steps.

[0084] Fourth, calculate the first temperature difference based on the first temperature value and the preset temperature value of the heating element.

[0085] Fifth, calculate the second temperature difference based on the second temperature value and the preset temperature value of the refrigeration element.

[0086] Sixth, the heat flux flowing through the sample to be tested is calculated based on the first temperature difference, the second temperature difference, and the heat transfer area.

[0087] According to an embodiment of the present invention, heat flux refers to the amount of heat passing through a unit area per unit time, and its unit is W / m², used to characterize the intensity of heat transfer. When there is a stable temperature difference (i.e., a preset temperature difference) between the two sides of the sample under test, heat will flow from the high-temperature side (heating element) to the low-temperature side (cooling element) through the sample under test. By measuring the temperature difference between the two sides and related parameters, the heat flux can be deduced.

[0088] Among them, the temperature of the heating element is set to The temperature of the refrigeration element is Then the preset temperature difference It can be calculated using formula (2).

[0089] Formula (2)

[0090] According to an embodiment of the present invention, a set of thermocouples can also be installed on the heating element and the cooling element respectively to measure the temperature at a depth of 1 mm on the surface of the heating element. , Temperature at the surface and 1mm depth inside the cooling element , Alternatively, the set temperatures of the heating and cooling elements can be used to replace the actual temperatures. That is, by default, the heating and cooling elements have reached their preset temperatures within a certain period of time.

[0091] Taking the set temperature of the heating element and the temperature of the cooling element as an example instead of the actual temperature, the calculation methods of the heat flux at the hot end and the heat flux at the cold end are respectively referred to formula (3) and formula (4).

[0092] Formula (3)

[0093] Formula (4)

[0094] in, The heat flux of the heating element. K represents the heat flux of the refrigeration element. s Let A be the thermal conductivity of the copper material, and A be the heat transfer area. The first temperature difference, This is the second temperature difference. The thickness of the heat transfer path from the center point of the heating element to the fourth thermocouple in the first group of thermocouples. The thickness of the heat transfer path from the fourth thermocouple in the second group to the center point of the cooling element is given. The heat transfer area A is calculated based on the actual contact area between the rotor and the low thermal resistance liquid metal composite material, and is obtained by correcting the rotor diameter and contact pressure.

[0095] After calculating the heat flux at the hot end and the heat flux at the cold end, the average value is taken as the heat flux through the low thermal resistance liquid metal composite material. That is, formula (5).

[0096] Formula (5)

[0097] Step 640: According to Fourier's law of thermal conductivity, the heat flux flowing through the low thermal resistance liquid metal composite material... Based on the temperature difference and temperature gradient, the thermal conductivity and thermal resistance of the low thermal resistance liquid metal composite material are calculated using reference formulas (6) and (7).

[0098] Formula (6)

[0099] Formula (7)

[0100] Where q is the heat flux density and k is the thermal conductivity. This represents the temperature gradient along the sample thickness.

[0101] According to embodiments of the present invention, the method for measuring rheological properties and thermal conductivity may further include the following steps.

[0102] First, based on rheological and thermal conductivity parameters, correlation calculations are performed according to the target model to determine the correlation relationship of low thermal resistance liquid metal composite materials at a preset shear rate.

[0103] The thermal conduction process of thermal interface materials (TIMs) involves a coupling of fluid properties and thermal conductivity. TIMs are used to fill the tiny gaps between the interfaces of solid materials, reducing contact thermal resistance and thus improving heat transfer efficiency. Common TIMs include thermal grease, thermal pads, and phase change materials. However, traditional thermal resistance models only focus on the intrinsic thermal resistance of the material and cannot effectively describe the effect of mechanical loads on the interfacial contact thermal resistance. From a physical perspective, the total thermal resistance is determined by the intrinsic thermal resistance of the thermal interface material layer. Thermal resistance at the interface It is formed by connecting and stacking in series.

[0104] In practical applications, total thermal resistance It consists of two parts, the intrinsic thermal resistance of TIM material and contact thermal resistance That is, formula (8).

[0105] Formula (8)

[0106] Intrinsic thermal resistance The result is obtained by referring to formula (9).

[0107] Formula (9)

[0108] in, Both m and are empirical constants, obtained by fitting the material system and test conditions; The intrinsic thermal conductivity of TIM material is calculated using formula (10).

[0109] Formula (10)

[0110] in, Thermal conductivity of the matrix material For fill volume, It is an empirical constant. d represents the microscopic interfacial contact thermal resistance, and d represents the filler size.

[0111] According to an embodiment of the present invention, when pressure P is applied to TIM, if P is greater than the yield stress... When a material undergoes plastic deformation, changes in its internal structure affect its thermal conductivity. Formula (9) is obtained through... It can quantify the effect of "rheological-mechanical load" on intrinsic thermal resistance. For example, the greater the pressure and the smaller the yield stress, the more significant the material deformation, and the intrinsic thermal resistance may change due to structural changes.

[0112] Contact thermal resistance The result is obtained by referring to formula (11).

[0113] Formula (11)

[0114] in, Both and n are empirical constants, obtained by fitting the material system and test conditions; G is the shear modulus; The surface roughness of the low thermal resistance liquid metal composite material is given by equation (11). Equation (11) can quantify the effect of this "interface-mechanical" coupling on the contact thermal resistance.

[0115] Furthermore, based on Fourier's law of thermal conduction, the total thermal resistance The thickness of the low thermal resistance liquid metal composite material is related to its thermal conductivity, which is given by formula (12).

[0116] Formula (12)

[0117] Therefore, through total thermal resistance The first model used to characterize the rheological performance parameters and the second model used to characterize the thermal conductivity parameters are linked to obtain the initial model, i.e., formula (13).

[0118] Formula (13)

[0119] According to embodiments of the present invention, the first model (Formulas 9 and 11) includes yield stress, pressure, and shear modulus, used to characterize the variation of the rheological properties of the low thermal resistance liquid metal composite material with applied load. The second model (Formula 12) includes thermal conductivity and contact thickness, used to characterize the variation of the thermal conductivity of the low thermal resistance liquid metal composite material with interface state. Specifically, BLT is used to characterize the actual contact thickness involved in heat conduction of the low thermal resistance liquid metal composite material under shear and pressure. The thermal conductivity of the low thermal resistance liquid metal composite material; Total thermal resistance; , These are empirical constants; Thermal conductivity of the matrix material; ρ is the yield stress; P is the compressive force; G is the shear modulus; m and n are the power law exponents. The surface roughness of a low thermal resistance liquid metal composite material.

[0120] According to an embodiment of the present invention, after obtaining the initial model, the target model is obtained according to the following steps: acquiring multiple historical samples; under a preset shear rate condition, collecting multiple sets of historical rheological performance parameters and historical thermal conductivity parameters corresponding to the multiple historical samples; substituting the historical rheological performance parameters and historical thermal conductivity parameters into the initial model, iteratively optimizing the empirical constants and power law exponents in the initial model, and obtaining the target model.

[0121] Based on multiple historical samples of the same type or system as low thermal resistance liquid metal composite materials, the rheological properties and thermal conductivity of each historical sample were measured at a preset shear rate and recorded. The collected historical parameters were substituted into the initial model to obtain empirical constants and power law exponents, so as to obtain the target model.

[0122] Second, based on the correlation, a performance control scheme for low thermal resistance liquid metal composite materials is generated. The performance control scheme includes the target shear rate, target temperature difference, or target ratio that need to be achieved to make the low thermal resistance liquid metal composite materials meet the preset performance requirements.

[0123] According to an embodiment of the present invention, after completing the correlation calculation of the rheological properties and thermal conductivity parameters of the low thermal resistance liquid metal composite material and clarifying the intrinsic relationship between the two at a preset shear rate, the properties of the material can be adjusted based on this correlation.

[0124] According to an embodiment of the present invention, the target ratio is the optimal mixing ratio of each component of the low thermal resistance liquid metal composite material, including the mass ratio, volume ratio or particle size distribution ratio of the base material and the functional filler in the low thermal resistance liquid metal composite material, wherein the functional filler is an additive that affects the rheological properties or thermal conductivity of the low thermal resistance liquid metal composite material.

[0125] Since different application scenarios have different performance requirements for samples (such as specific thermal conductivity, rheological adaptability, etc.), preset performance requirements are to clarify the specific performance indicators that the sample needs to achieve in actual use. For example, electronic packaging materials need to meet the requirements of thermal conductivity and rheological properties under specific temperature differences and shear conditions.

[0126] Based on the established correlations, and through reverse derivation, starting from the preset performance requirements, the key parameters that need to be controlled during the processing or use of the sample to achieve these requirements are calculated. Specifically, if it is necessary to improve thermal conductivity while ensuring good rheological processability, the adjustment range of the shear rate needs to be determined according to the correlations, and this range is defined as the target shear rate. Additionally, the target temperature difference between the heating and cooling elements is set. Through the synergistic effect of these parameters, the sample ultimately meets the preset performance standards, thereby optimizing the rheological and thermal conductivity properties of this low thermal resistance liquid metal composite material.

[0127] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for jointly measuring rheological properties and thermal conductivity, characterized in that, The method includes: Place the sample to be tested on the first surface of the tray; Adjust the position of the rotor unit so that the rotor head approaches the first surface of the tray and contacts the surface of the sample to be tested; The heating element and the cooling element are turned on so that the heating surface of the heating element transfers heat to the rotating head through the rotating rod, and then to the sample to be tested through the rotating head; and the cooling surface of the cooling element transfers cold energy to the sample to be tested through the tray, so that the temperature of the sample to be tested is maintained within a predetermined temperature range under the combined action of the heating element and the cooling element. The rotor unit is turned on so that the rotating rod drives the rotor head to rotate, so that the rotor head can shear and stir the sample to be tested at a preset shear rate; Maintaining the preset shear rate, the rheological properties and thermal conductivity of the sample under test are measured to obtain rheological property parameters and thermal conductivity parameters.

2. The method according to claim 1, characterized in that, The method further includes: Based on the rheological and thermal conductivity parameters, correlation calculations are performed according to the target model to determine the correlation relationship of the test sample at the preset shear rate. Based on the correlation, a performance control scheme for the test sample is generated. The performance control scheme includes the target shear rate, target temperature difference, or target ratio that needs to be achieved to make the test sample meet the preset performance requirements.

3. The method according to claim 2, characterized in that, The target ratio includes the mass ratio, volume ratio, or particle size distribution ratio of the base material and the functional filler in the sample to be tested, wherein the functional filler is an additive that affects the rheological properties or thermal conductivity of the sample to be tested.

4. The method according to claim 2, characterized in that, The target model is obtained according to the following steps; Obtain multiple historical samples; Under the preset shear rate conditions, multiple sets of historical rheological performance parameters and historical thermal conductivity parameters corresponding to the multiple historical samples are collected. Substitute the historical rheological performance parameters and the historical thermal conductivity parameters into the initial model, and iteratively optimize the empirical constants and power-law exponents in the initial model to obtain the target model.

5. The method according to claim 4, characterized in that, The initial model includes a first model and a second model. The first model includes yield stress, pressure, and shear modulus, used to characterize the variation of the rheological properties of the sample under test with applied load. The second model includes thermal conductivity and contact thickness, used to characterize the variation of the thermal conductivity of the sample under test with interface state. The initial model is as follows: BLT is used to characterize the contact thickness of the sample under test that actually participates in heat conduction under shear and pressure. The thermal conductivity of the sample under test; Total thermal resistance; , These are empirical constants; Thermal conductivity of the matrix material; ρ is the yield stress; P is the compressive force; G is the shear modulus; m and n are the power law exponents. The surface roughness of the sample to be tested.

6. The method according to claim 1, characterized in that, The rheological performance parameters include at least the thickness of the sample under test, and the thermal conductivity parameters include at least the heat flux flowing through the sample under test and the thermal conductivity and thermal resistance of the sample under test. The rheological and thermal conductivity properties of the sample under test are measured to obtain rheological and thermal conductivity parameters, including: Acquire torque data, angular velocity, pressure data, and multiple temperature data fed back by the sample under test; The thickness of the sample to be tested is calculated based on the preset shear rate, the torque data, and the pressure data. Based on the multiple temperature data and the preset temperature difference, the heat flux flowing through the sample to be tested is calculated, wherein the preset temperature difference is the temperature difference between the heating element and the cooling element; The thermal conductivity of the sample is calculated based on the heat flux flowing through it and the preset temperature difference.

7. The method according to claim 6, characterized in that, The thickness of the sample to be tested is calculated based on the preset shear rate, the torque data, and the pressure data, including: The viscosity of the sample to be tested is calculated based on the preset shear rate and the torque data. The yield stress of the sample under test is calculated based on the viscosity and the preset shear rate. The thickness of the sample to be tested is calculated based on the yield stress and the pressure data.

8. The method according to claim 6, characterized in that, The multiple temperature data include: a first temperature value of the rotating head and a second temperature value of the tray; Based on the multiple temperature data and the preset temperature difference, the heat flux flowing through the sample to be tested is calculated, including: Calculate the first temperature difference based on the first temperature value and the preset temperature value of the heating element; The second temperature difference is calculated based on the second temperature value and the preset temperature value of the refrigeration element; The heat flux flowing through the sample under test is calculated based on the first temperature difference, the second temperature difference, and the heat transfer area.

9. A device for jointly measuring rheological properties and thermal conductivity, characterized in that, include: The tray includes a first surface and a second surface, wherein the first surface is used to hold the sample to be tested. The rotor unit includes a rotating rod and a rotating head. The rotating rod includes a first end and a second end. The first end is connected to the rotating head. When the rotor unit is in operation, the rotating head is in a rotating state to shear and stir the sample to be tested in the tray. Heating element, including heating surface; Refrigeration components, including cooling surfaces; The first end of the rotating rod is connected to the heating surface through surface contact, so that the heat from the heating surface is transferred to the rotating head through the rotating rod, and then to the sample to be tested through the rotating head. The second surface of the tray is connected to the cooling surface through surface contact, so that the cooling energy of the cooling surface is transferred to the sample to be tested through the tray.

10. The combined measuring device according to claim 9, characterized in that, The combined measuring equipment also includes: A torque sensor is configured between the rotor unit and the heating element to detect the torque data fed back by the sample under test; A true displacement sensor is configured on the upper part of the rotor unit for measuring the thickness of the sample to be tested; Multiple thermocouples, wherein a first set of thermocouples is disposed on the rotor; and a second set of thermocouples is disposed on the tray; A pressure sensor is configured between the tray and the cooling element to detect the pressure data fed back by the sample under test.

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