A portable device and method for measuring the contact angle of molten metal droplets with adjustable temperature

Abstract

A portable, temperature-adjustable molten metal droplet contact angle measurement device and method are disclosed. The device includes a heating stage, a temperature-adjustable pipette for absorbing and releasing molten metal droplets, a supplementary light source, an industrial CCD camera for capturing images, an image processing computer for analyzing data, and a support for adjusting the positions of the supplementary light and the camera. The measurement method includes: placing the solid sample to be tested on the heating stage and heating it to a set temperature to completely melt the molten metal; absorbing the droplet using the temperature-adjustable pipette and transferring it to the sample surface; adjusting the relative positions of the supplementary light and the industrial CCD camera; acquiring real-time images of the droplet wetting morphology and inputting them into the computer; processing the images through an image analysis module to obtain the contact angle of the droplet on the sample surface. This invention is compact, portable, and easy to operate. It can be placed entirely in a vacuum glove box and is particularly suitable for measuring the contact angle of lithium metal in an inert atmosphere. The measurement is safe, reliable, and highly adaptable.

Description

Technical Field

[0001] This invention relates to the field of molten metal droplet contact angle measurement, and in particular to a portable adjustable temperature molten metal droplet contact angle measurement device and method, which is suitable for measuring the contact angle between conventional solids and molten metals, and can also be applied to the wettability assessment of solid electrolytes protected by inert gas and lithium metal. Background Technology

[0002] The contact angle of molten metal droplets is a crucial physical parameter for evaluating the wettability of molten metal on a solid surface. It holds significant reference value for material interface optimization design, welding process optimization, and the development of novel electrode interface micro / nano structures, and has been widely applied in various technical fields such as metal smelting, aerospace, and new energy battery materials. In particular, the study of the wettability of molten lithium metal on solid electrolyte surfaces is critical in the development of high-energy-density solid-state battery technology. Good wettability not only helps reduce interfacial resistance and improve ion transport efficiency but also effectively suppresses dendrite growth at the interface, ensuring the safe and stable operation of high-capacity solid-state batteries.

[0003] However, measuring the contact angle of molten metal droplets requires stringent experimental conditions. It typically necessitates simultaneous and precise temperature control of the sample stage and the metal droplet. Furthermore, for some reactive metals (such as lithium), operation must be performed within an inert atmosphere or a sealed glove box to prevent oxidation or other side reactions. Existing measurement methods largely rely on large heating devices combined with vacuum chambers, resulting in high costs, bulky size, and complex operation. For example, patent CN110274850 A discloses a contact angle testing device and method, and patent CN110631966 B discloses a high-temperature liquid droplet contact angle measurement device and method. These methods lack portability and cannot operate within the limited space of a vacuum glove box, failing to meet the demands for rapid and flexible measurement of molten metal droplet contact angles in various scenarios. Therefore, there is an urgent need to develop a compact, temperature-adjustable, vacuum-operable, and portable molten metal droplet contact angle measurement device to overcome the shortcomings of existing technologies. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a portable adjustable temperature molten metal droplet contact angle measuring device and method, which solves the problems of existing contact angle measuring devices being bulky, complex to operate, and difficult to use flexibly in closed or restricted environments. It meets the requirements of high efficiency, accuracy, and safety in measuring the wettability of molten metal droplets on sample surfaces in multiple scenarios, and is particularly suitable for high temperature contact angle testing of lithium metal.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A portable, temperature-adjustable molten metal droplet contact angle measuring device, housed in a vacuum glove box, includes a heating stage 3 for uniformly heating a solid sample, a temperature-adjustable pipette 6 for picking up and transferring molten metal droplets, a supplementary light 1 for providing supplementary illumination, an industrial CCD camera 7 for acquiring images, and an image processing computer 9 for image processing and contact angle analysis; wherein the heating stage 3, temperature-adjustable pipette 6, supplementary light 1, and industrial CCD camera 7 are all housed in the vacuum glove box, and the industrial CCD camera 7 communicates with the image processing computer 9 via wired or wireless means; The adjustable temperature pipette 6 includes a high-temperature resistant alumina tube 12, with a rubber cap 10 at the top. The high-temperature resistant alumina tube 12 is equipped with a heat-insulating handle sleeve 11 and a thermocouple probe 14 on the outside. A rewound mica heating core 13 is provided at the lower end of the high-temperature resistant alumina tube 12. The rewound mica heating core 13, the thermocouple probe 14 and the micro temperature controller 15 are connected to form a closed-loop temperature control system.

[0006] When testing lithium metal samples, the lower half of the high-temperature resistant corundum tube 12 that is in contact with lithium metal needs to be replaced with a stainless steel tube, which is connected to the upper half of the corundum tube by threads.

[0007] The supplementary light 1 is mounted on the supplementary light tripod 2, and the industrial CCD camera 7 is mounted on the camera tripod 8. Both the tripod 2 and the camera tripod 8 are adjustable in height and relative position to ensure that the sample to be tested is located at the central optical axis and focusing position of the supplementary light 1 and the industrial CCD camera 7.

[0008] The heating stage 3 integrates a heating device and a temperature control system, which can uniformly heat the sample within the required temperature range, so that the molten metal sample 5 to be tested melts and the solid sample 4 to be tested remains solid.

[0009] The temperature control system of the adjustable temperature pipette 6 is set to the same target operating temperature as the temperature control system of the heating stage 3, which enables isothermal matching control of the upper and lower temperature zones.

[0010] The solid sample 4 to be tested is a garnet-type solid electrolyte; The molten metal sample 5 to be tested includes molten lithium, copper, gold, nickel, cobalt, platinum, tin, and zinc.

[0011] A method for measuring the contact angle of a portable, temperature-adjustable molten metal droplet includes the following steps: S1: Adjust the height and relative position of the tripod of the supplementary light 1 and the industrial CCD camera 7, and place the contact point of the solid sample 4 and the molten metal sample 5 to be tested at the focal point of clear imaging. S2: The heating stage 3 and the adjustable temperature pipette 6 start heating synchronously until the molten metal sample 5 to be tested is completely melted to obtain metal droplets; S3: Transfer the molten metal sample 5 to be tested onto the surface of the solid sample 4 using the temperature-adjustable pipette 6; S4: The industrial CCD camera 7 captures the contact process between the metal droplet and the surface of the solid sample 4 in real time, transmits the image to the computer, and uses the image processing module to calculate the droplet contact angle value.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The adjustable temperature pipette independently designed in this invention has a compact structure that integrates heating and temperature control. It can independently and precisely regulate the temperature of molten metal droplets. Furthermore, by setting the temperature control module of the adjustable temperature pipette and the temperature control system of the heating stage to the same target operating temperature, isothermal matching control of the upper and lower temperature zones is achieved. This design effectively eliminates the interfacial temperature gradient generated when high-temperature droplets fall onto the surface of a solid sample, which can effectively ensure the temperature consistency between the sample and the molten metal droplets, thereby significantly improving the reliability and accuracy of contact angle testing.

[0013] 2. The entire device is small in size and light in weight, and can be flexibly arranged and operated in confined spaces such as vacuum glove boxes, which greatly improves the adaptability and portability of the measuring device.

[0014] 3. The core module adopts a low-cost and easy-to-operate mica heating core, K-type thermocouple, and mature optical acquisition and analysis system to replace traditional large-scale high-temperature contact angle testing equipment. This not only reduces the overall equipment cost but also simplifies the operation process, making it convenient for widespread use in multiple scenarios.

[0015] In summary, this invention is small in size and light in weight, and can be placed in an inert gas protective glove box for operation according to different measurement needs, preventing molten metal droplets from reacting adversely with moisture, oxygen, etc., and ensuring the safety of the experimental process and the validity of the measurement results. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0017] Figure 2 This is a schematic diagram of an adjustable temperature pipette.

[0018] Figure 3 This is a diagram showing the effect of measuring the contact angle of molten lithium metal on the surface of a solid electrolyte after surface polishing.

[0019] In the diagram: 1-Supplemental light; 2-Supplemental light tripod; 3-Heating stage; 4-Solid sample to be tested; 5-Molten metal sample to be tested; 6-Temperature adjustable pipette; 7-Industrial CCD camera; 8-Camera tripod; 9-Computer; 10-Rubber cap; 11-Insulated handle sleeve; 12-High-temperature resistant corundum tube; 13-Rewound mica heating element; 14-Thermocouple probe; 15-Miniature temperature controller. Detailed Implementation

[0020] To more clearly demonstrate the features and advantages of this patent, the portable adjustable temperature molten metal droplet contact angle measuring device proposed in this invention will be further described below with reference to the accompanying drawings.

[0021] Reference Figure 1 A portable, temperature-adjustable molten metal droplet contact angle measuring device is provided. It is placed in a vacuum glove box and operated within the vacuum glove box to avoid the molten metal droplets reacting with air or moisture, thereby effectively preventing oxidation or other side reactions and preventing the sample from reacting with the external environment. This device is particularly suitable for studying the wettability of lithium metal under high-temperature conditions, ensuring the safety of the testing process and the reliability of the data.

[0022] The present invention includes a heating stage 3 for uniformly heating a solid sample, a temperature-adjustable pipette 6 for picking up and transferring molten metal droplets, a supplementary light 1 for providing supplementary lighting, an industrial CCD camera 7 for acquiring images, and an image processing computer 9 for image processing and contact angle analysis.

[0023] The supplementary light 1 and the industrial CCD camera 7 are both arranged on both sides of the heating stage 3 and fixed by the supplementary light tripod 2 and the camera tripod 8. The tripod 2 and the camera tripod 8 are both adjustable in height and relative position to ensure that the sample to be tested is located at the central optical axis and focusing position of the supplementary light 1 and the industrial CCD camera 7.

[0024] Reference Figure 2 The adjustable temperature pipette 6 includes a high-temperature resistant corundum tube 12, with a rubber cap 10 at the top. An insulated handle sleeve 11 and a thermocouple probe 14 are installed on the outside of the tube. A rewound mica heating element 13 is located at the lower end of the tube. The rewound mica heating element 13, the thermocouple probe 14, and a micro-temperature controller 15 are connected to form a closed-loop temperature control system for real-time monitoring and precise adjustment of the pipette temperature. When the rubber cap 10 is squeezed, it creates a pressure difference between the inside and outside of the pipette, facilitating the aspiration and transfer of molten metal droplets. The rewound mica heating element heats the outer wall of the corundum tube, and the thermocouple measures the temperature in real time. Both are adjusted in a closed loop by the micro-temperature controller to achieve stable temperature control of the pipette, preventing sudden temperature changes during the transfer and release of the molten metal droplets from affecting the measurement results.

[0025] During operation, the operator draws molten metal droplets by squeezing the rubber cap 10 and applies them to the surface of the sample to be tested. To prevent the metal droplets from solidifying during transfer, a mica heating core 13 wrapped around the corundum tube 12 provides continuous heating, a thermocouple probe 14 monitors the droplet temperature in real time, and a micro temperature controller 15 adjusts the power of the heating core to ensure stable pipette temperature.

[0026] When testing lithium metal samples, the lower half of the high-temperature resistant corundum tube 12 that comes into contact with the lithium metal needs to be replaced with a stainless steel tube. The stainless steel tube is connected to the upper half of the corundum tube by threads, which can effectively prevent the high-temperature molten lithium metal from reacting with the corundum tube.

[0027] The heating stage 3 integrates a heating device and a temperature control system, enabling uniform heating of the sample within the required temperature range. This prevents sample breakage or test data deviation caused by localized temperature differences, ensuring the repeatability and reliability of contact angle measurements. The temperature control system of the adjustable temperature pipette is set to the same target operating temperature as the heating stage's temperature control system, achieving isothermal matching control of the upper and lower temperature zones.

[0028] Specifically, the heating stage 3 is a commercially available product, a fully integrated heating stage with a wrapped edge, model V-1515. It includes a thermally conductive substrate, a heating tube embedded inside the thermally conductive substrate, and a temperature sensor, preferably a K-type thermocouple, positioned near the surface of the thermally conductive substrate. The temperature sensor is communicatively connected to an external temperature control module to collect the temperature signal above the thermally conductive substrate in real time and feed it back to the temperature control module. The temperature control module dynamically adjusts the output power of the heating tube based on a PID control algorithm, forming a closed-loop temperature control system. Through the above structural combination, a uniform thermal field can be provided for the solid electrolyte sample and the metal block to be melted, which are placed flat on the thermally conductive substrate. This avoids uneven heating rates that could cause thermal stress inside the ceramic sample, leading to microcracks or rupture, thereby ensuring the stability of the interface of the molten metal droplets at the set temperature and ensuring the repeatability and reliability of the measurement data.

[0029] The solid sample 4 to be tested is a garnet-type solid electrolyte, exhibiting hard and brittle ceramic properties; The molten metal sample 5 to be tested is mainly molten lithium, but it can also be extended to other molten metal samples, such as molten copper (Cu), gold (Au), nickel (Ni), cobalt (Co), platinum (Pt), tin (Sn), and zinc (Zn). Molten lithium has extremely high chemical reactivity and is prone to side reactions during testing, requiring a stringent experimental environment, generally placed in a vacuum glove box. The measurement method using the aforementioned portable adjustable-temperature molten metal droplet contact angle measuring device mainly includes the following steps: S1: Adjust the height and relative position of the tripod of the supplementary light 1 and the industrial CCD camera 7, and place the contact point of the solid sample 4 and the molten metal sample 5 to be tested at the focal point of clear imaging. S2: The heating stage 3 and the adjustable temperature pipette 6 start heating synchronously until the molten metal sample 5 to be tested is completely melted to obtain metal droplets; S3: Transfer the molten metal sample 5 to be tested onto the surface of the solid sample 4 using the temperature-adjustable pipette 6; S4: The industrial CCD camera 7 acquires side images of the contact process between the metal droplet and the surface of the solid sample 4 in real time, and transmits the images to the computer; The image processing module in the computer first performs grayscale and binarization on the acquired side image to enhance the contrast of the droplet edge. Then, it uses an edge detection algorithm (Canny edge detection operator) to extract the coordinates of the droplet's contour edge points and determine the solid-liquid contact baseline between the metal droplet and the solid sample surface. Based on the extracted contour coordinate points, a curve fitting algorithm (B-spline curve fitting) is used to reconstruct the droplet's shape curve. By calculating the tangent of the fitted curve at the solid-liquid three-phase intersection point, the angle between the tangent and the solid-liquid contact baseline is obtained, which is the contact angle value. This enables automated extraction of measurement data and improves the accuracy and efficiency of the measurement.

[0030] Reference Figure 3 This paper presents the actual measurement results of the contact angle of molten lithium on the surface of a garnet-type solid electrolyte. The measurement results show that the molten lithium surface is smooth and free of obvious impurities. During the measurement process, the device can acquire real-time side images of the droplet on the sample surface and process the images using analysis software to automatically calculate the contact angle value and related wettability parameters, thereby effectively improving the efficiency and accuracy of the measurement.

Claims

1. A portable adjustable temperature molten metal droplet contact angle measuring device, characterized by, The system includes a heating stage (3) for uniformly heating the solid sample (4) and the molten metal sample (5) to be tested; a temperature-adjustable pipette (6) for aspirating and transferring molten metal droplets onto the surface of the solid sample (4); a supplementary light (1) for providing supplementary light; an industrial CCD camera (7) for acquiring images; and an image processing computer (9) for image processing and contact angle analysis. The heating stage (3), temperature-adjustable pipette (6), supplementary light (1), and industrial CCD camera (7) are all placed in a vacuum glove box. The industrial CCD camera (7) communicates with the image processing computer (9) via wired or wireless means. The adjustable temperature pipette (6) includes a high-temperature resistant alumina tube (12), the top of which is a rubber cap (10). The high-temperature resistant alumina tube (12) is provided with a heat-insulating handle sleeve (11) and a thermocouple probe (14) on the outside. A rewound mica heating core (13) is provided at the lower end of the high-temperature resistant alumina tube (12). The rewound mica heating core (13), the thermocouple probe (14) and the micro temperature controller (15) are connected to form a closed-loop temperature control system.

2. The portable adjustable temperature molten metal droplet contact angle measuring device according to claim 1, characterized in that, When testing lithium metal samples, the lower half of the high-temperature resistant corundum tube (12) that is in contact with lithium metal is replaced by a stainless steel tube and connected to the upper half of the corundum tube by a thread.

3. The portable adjustable temperature molten metal droplet contact angle measuring device according to claim 1, characterized in that, The supplementary light (1) is set on the supplementary light tripod (2) and the industrial CCD camera (7) is set on the camera tripod (8). Both the tripod (2) and the camera tripod (8) are adjustable in height and relative position, ensuring that the contact position between the solid sample (4) to be tested and the molten metal droplet is located at the central optical axis and focusing position of the supplementary light (1) and the industrial CCD camera (7).

4. The portable adjustable temperature molten metal droplet contact angle measuring device according to claim 1, characterized in that, The heating stage (3) integrates a heating device and a temperature control system, which can uniformly heat the sample within the required temperature range, so that the molten metal sample (5) to be tested melts and the solid sample (4) to be tested remains solid.

5. A portable adjustable temperature molten metal droplet contact angle measuring device according to claim 4, characterized in that, The temperature control system of the adjustable temperature pipette (6) and the temperature control system of the heating stage (3) are set to the same target working temperature, which can realize isothermal matching control of the upper and lower temperature zones.

6. The measurement method of the portable adjustable temperature molten metal droplet contact angle measuring device according to claim 1, characterized in that, The solid sample to be tested (4) is a garnet-type solid electrolyte.

7. The measurement method of the portable adjustable temperature molten metal droplet contact angle measuring device according to claim 1, characterized in that, The molten metal sample to be tested (5) includes molten metals lithium, copper, gold, nickel, cobalt, platinum, tin, and zinc.

8. The measurement method of the portable adjustable temperature molten metal droplet contact angle measuring device according to claim 1, characterized in that, It includes the following steps: S1: Adjust the height and relative position of the tripod of the supplementary light (1) and the industrial CCD camera (7) to place the contact point between the solid sample (4) to be tested and the molten metal droplet at a focal point with clear imaging. S2: The heating stage (3) and the adjustable temperature pipette (6) start to heat synchronously until the molten metal sample (5) to be tested is completely melted to obtain molten metal droplets; S3: The molten metal droplets are transferred to the surface of the solid sample (4) to be tested using a temperature-adjustable pipette (6); S4: The industrial CCD camera (7) collects the contact process between the metal droplet and the surface of the solid sample (4) in real time, transmits the image to the computer, and uses the image processing module to calculate the droplet contact angle value.

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