Research Progress and Prospect of Gallium-Based Liquid Metals in Electrical-Thermal-Mechanics Field
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摘要:
液态金属兼顾液体和金属的特性,其研究与应用在工学各领域兴起. 镓基液态金属常温下呈液态,具有高沸点、高电导率、高热导率、安全无毒等优良特性,在电学、热学、力学和生物医疗等诸多领域取得了广泛的应用. 目前,镓基液态金属已成为前沿研究热点. 通过综合对比国内外研究现状,介绍镓基液态金属的制备方法及其性能改善的措施,分析几种典型镓基液态金属的理化性质,总结镓基液态金属在电力设备、柔性电子、电源储能、散热冷却、载流摩擦、极压润滑等应用领域的功能原理与研究进展,并提出其未来研究重点. 基于镓基液态金属合金的特性,对其在材料改性、新型电子器件、太阳能电池、轨道交通、电磁弹射等领域具有的应用潜力进行分析和展望.
Abstract:Liquid metal takes into account the characteristics of both liquid and metal, and it is increasingly studied and applied in various fields of engineering. Gallium-based liquid metal is liquid at room temperature, with a high boiling point, high electrical conductivity, high thermal conductivity, safety, non-toxicity, and other excellent characteristics, and it has been widely used in many fields such as electricity, heat, mechanics, and biomedicine. At present, gallium-based liquid metals have become a frontier research hotspot. By comprehensively comparing the research status in China and abroad, the preparation methods and performance improvement measures of gallium-based liquid metals were introduced, and the physical and chemical properties of several typical gallium-based liquid metals were analyzed. The functional principles and research progress of gallium-based liquid metals in the fields of power equipment, flexible electronics, power storage, heat dissipation cooling, current-carrying friction, and extreme pressure lubrication were summarized, and its future research focus was put forward. Based on the characteristics of gallium-based liquid metals, their potential applications in material modification, new electronic devices, solar cells, rail transit, electromagnetic ejection, and other fields were analyzed and prospected.
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[1] SONG H, KIM T, KANG S, et al. Ga-based liquid metal micro/nanoparticles: recent advances and applications[J]. Small, 2020, 16(12): 1903391.1-1903391.21. [2] 王曦宇,李科,王源升,等. 聚合物/镓基液态金属复合材料的研究及应用进展[J]. 高分子材料科学与工程,2021,37(1): 327-334.WANG Xiyu, LI Ke, WANG Yuansheng, et al. Progress of polymer/gallium-based liquid metal composites[J]. Polymer Materials Science & Engineering, 2021, 37(1): 327-334. [3] BO G Y, REN L, XU X, et al. Recent progress on liquid metals and their applications[J]. Advances in Physics: X, 2018, 3(1): 1446359.1-1446359.32. [4] DING Y R, ZENG M Q, FU L. Surface chemistry of gallium-based liquid metals[J]. Matter, 2020, 3(5): 1477-1506. doi: 10.1016/j.matt.2020.08.012 [5] 邓中山. 蓬勃发展的液态金属新工业[J]. 科学,2022,74(2): 31-34.DENG Zhongshan. The booming new liquid metal industry[J]. Science, 2022, 74(2): 31-34. [6] 刘辰,曹召勋,王雅仙,等. 液态金属镓铟锡合金材料制备及导热性能研究[J]. 兵器材料科学与工程,2021,44(6): 99-103.LIU Chen, CAO Zhaoxun, WANG Yaxian, et al. Preparation and thermal conductivity of liquid metal GaInSn alloys[J]. Ordnance Material Science and Engineering, 2021, 44(6): 99-103. [7] 耿继业,李思佳,蓝嘉昕,等. 基于镓基液态金属玻璃倾斜开关的制备及研究[J]. 材料科学与工艺,2021,29(4): 74-80. doi: 10.11951/j.issn.1005-0299.20200158GENG Jiye, LI Sijia, LAN Jiaxin, et al. Research on preparation and wettability of gallium based liquid metal glass tilt switch[J]. Materials Science and Technology, 2021, 29(4): 74-80. doi: 10.11951/j.issn.1005-0299.20200158 [8] 乔竹辉, 于源, 刘维民, 等. 一种高导电、强润滑镓基液态金属润滑剂的制备方法: CN114634835B[P]. 2023-03-24. [9] 张配同,刘宜伟,郭强,等. 超声法制备均匀分布的亚微米级镓铟锡合金液态金属微球[J]. 理化检验(物理分册),2017,53(10): 701-706.ZHANG Peitong, LIU Yiwei, GUO Qiang, et al. Uniformly distributed sub-microsized galinstan liquid metal microspheres prepared by ultrasoic method[J]. Physical Testing and Chemical Analysis (Part A: Physical Testing), 2017, 53(10): 701-706. [10] YU F, XU J L, LI H Q, et al. Ga-In liquid metal nanoparticles prepared by physical vapor deposition[J]. Progress in Natural Science: Materials International, 2018, 28(1): 28-33. doi: 10.1016/j.pnsc.2017.12.004 [11] DUAN L F, ZHANG Y M, ZHAO J H, et al. Unique surface fluorescence induced from the core-shell structure of gallium-based liquid metals prepared by thermal oxidation processing[J]. ACS Applied Materials & Interfaces, 2022, 14(34): 39654-39664. [12] BAI P P, LI S W, TAO D S, et al. Tribological properties of liquid-metal galinstan as novel additive in lithium grease[J]. Tribology International, 2018, 128: 181-189. doi: 10.1016/j.triboint.2018.07.036 [13] YANG J, CHENG W L, KALANTAR-ZADEH K. Electronic skins based on liquid metals[J]. Proceedings of the IEEE, 2019, 107(10): 2168-2184. doi: 10.1109/JPROC.2019.2908433 [14] REN L, XU X, DU Y, et al. Liquid metals and their hybrids as stimulus-responsive smart materials[J]. Materials Today, 2020, 34: 92-114. doi: 10.1016/j.mattod.2019.10.007 [15] CHENG J, YU Y, GUO J, et al. Ga-based liquid metal with good self-lubricity and high load-carrying capacity[J]. Tribology International, 2019, 129: 1-4. doi: 10.1016/j.triboint.2018.08.003 [16] HAYASHI Y, SANEIE N, YIP G, et al. Metallic nanoemulsion with galinstan for high heat-flux thermal management[J]. International Journal of Heat and Mass Transfer, 2016, 101: 1204-1216. doi: 10.1016/j.ijheatmasstransfer.2016.05.139 [17] LIU T Y, SEN P, KIM C J. Characterization of nontoxic liquid-metal alloy galinstan for applications in microdevices[J]. Journal of Microelectromechanical Systems, 2012, 21(2): 443-450. doi: 10.1109/JMEMS.2011.2174421 [18] KIM D, LEE Y, LEE D W, et al. Hydrochloric acid-impregnated paper for gallium-based liquid metal microfluidics[J]. Sensors and Actuators B: Chemical, 2015, 207: 199-205. doi: 10.1016/j.snb.2014.09.108 [19] 徐明宇,陈渭. 液态金属用作润滑剂的研究现状与展望[J]. 机械工程学报,2020,56(9): 137-146. doi: 10.3901/JME.2020.09.137XU Mingyu, CHEN Wei. Research progress and prospect of liquid metals used as lubricants[J]. Journal of Mechanical Engineering, 2020, 56(9): 137-146. doi: 10.3901/JME.2020.09.137 [20] 孙振权,刘炜,吕思雨,等. 镓铟锡液态金属磁收缩机理研究[J]. 高压电器,2018,54(12): 12-17,23.SUN Zhenquan, LIU Wei, LYU Siyu, et al. Research on the magnetic pinch mechanism of GaInSn liquid metal[J]. High Voltage Apparatus, 2018, 54(12): 12-17,23. [21] 陈德桂. 两种新的限流技术[J]. 低压电器,2005(4): 3-4,37.CHEN Degui. Two kinds of limiting technologies[J]. Low Voltage Apparatus, 2005(4): 3-4,37. [22] NIAYESH K, TEPPER J, KONIG F. A novel current limitation principle basedon application of liquid metals[J]. IEEE Transactions on Components and Packaging Technologies, 2006, 29(2): 303-309. doi: 10.1109/TCAPT.2006.875880 [23] SHEN T, ZHANG D X, HUANG L, et al. An automatic-recovery inertial switch based on a gallium-indium metal droplet[J]. Journal of Micromechanics and Microengineering, 2016, 26(11): 115016.1-115016.8. [24] 刘瑞. 镓铟锡微流体惯性开关的液体精密操控研究[D]. 无锡: 江南大学, 2021. [25] 杨文振, 刘禹, 刘瑞, 等. 刻蚀-相分离法表面疏液处理提升液态金属基微流体惯性开关阈值性能[J/OL]. 机械工程学报. (2022-05-30)[2022-06-26]. http://kns.cnki.net/kcms/detail/11.2187.TH.20220526.1849.120. html. [26] JEON J, LEE J B, CHUNG S K, et al. Magnetic liquid metal marble: wireless manipulation of liquid metal droplet for electrical switching applications[C]//The 18th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS). Anchorage: IEEE, 2015: 1834- 1837. [27] DICKEY M D. Stretchable and soft electronics using liquid metals[J]. Advanced Materials, 2017, 29(27): 1606425.1-1606425-19. [28] DICKEY M D, CHIECHI R C, LARSEN R J, et al. Eutectic gallium-indium (EGaIn): a liquid metal alloy for the formation of stable structures in microchannels at room temperature[J]. Advanced Functional Materials, 2008, 18(7): 1097-1104. doi: 10.1002/adfm.200701216 [29] 陈济桁. 美国空军实验室研发新型液态金属导体[J]. 国际航空,2020(1): 70-72.CHEN Jiheng. AFRL develops new liquid metal conductor[J]. International Aviation, 2020(1): 70-72. [30] 耿继业,蓝嘉昕,刘通,等. 3D 打印聚氨酯微流道封装镓基液态金属柔性导线及其性能[J]. 材料导报,2021,35(20): 20040-20044. doi: 10.11896/cldb.20080168GENG Jiye, LAN Jiaxin, LIU Tong, et al. Fabrication and properties of flexible gallium-based liquid metal wires encapsulated in 3D printed polyurethane microchannel[J]. Materials Reports, 2021, 35(20): 20040-20044. doi: 10.11896/cldb.20080168 [31] NEUMANN T V, DICKEY M D. Liquid metal direct write and 3D printing: a review[J]. Advanced Materials Technologies, 2020, 5(9): 2000070.1-2000070.16. [32] COOK A, PAREKH D P, LADD C, et al. Shear-driven direct-write printing of room-temperature gallium-based liquid metal alloys[J]. Advanced Engineering Materials, 2019, 21(11): 1900400.1-1900400.10. [33] YIN J Z, SANTOS V J, POSNER J D. Bioinspired flexible microfluidic shear force sensor skin[J]. Sensors and Actuators A: Physical, 2017, 264: 289-297. doi: 10.1016/j.sna.2017.08.001 [34] MENGÜÇ Y, PARK Y L, PEI H, et al. Wearable soft sensing suit for human gait measurement[J]. The International Journal of Robotics Research, 2014, 33(14): 1748-1764. doi: 10.1177/0278364914543793 [35] 秦琴,刘宜伟,王永刚,等. 基于液态金属的柔性导线的制备方法研究进展[J]. 电子元件与材料,2017,36(4): 1-8.QIN Qin, LIU Yiwei, WANG Yonggang, et al. Recent progress of methods for fabricating flexible conductive wires based on liquid metals[J]. Electronic Components and Materials, 2017, 36(4): 1-8. [36] 周酉林,刘宜伟,郭智勇,等. 基于液态金属的可拉伸导线制备与性能研究[J]. 功能材料,2018,49(3): 3152-3155,3159.ZHOU Youlin, LIU Yiwei, GUO Zhiyong, et al. Preparation and properties of stretchable conductive wires based on liquid metal[J]. Journal of Functional Materials, 2018, 49(3): 3152-3155,3159. [37] 刘岚, 巫运辉, 郑荣敏, 等. 一种基于液态金属的可拉伸柔性功能导体及其制备方法: CN108447592A[P]. 2018-08-24. [38] ZHU S, SO J H, MAYS R, et al. Ultrastretchable fibers with metallic conductivity using a liquid metal alloy core[J]. Advanced Functional Materials, 2013, 23(18): 2308-2314. doi: 10.1002/adfm.201202405 [39] 李海燕,刘静. 基于液态金属墨水的直写式可拉伸变阻器[J]. 电子机械工程,2014,30(1): 29-33. doi: 10.3969/j.issn.1008-5300.2014.01.008LI Haiyan, LIU Jing. Directly-printable stretchable variable resistor based on liquid metal ink[J]. Electro-Mechanical Engineering, 2014, 30(1): 29-33. doi: 10.3969/j.issn.1008-5300.2014.01.008 [40] BOLEY J W, WHITE E L, KRAMER R K. Mechanically sintered gallium-indium nanoparticles[J]. Advanced Materials, 2015, 27(14): 2355-2360. doi: 10.1002/adma.201404790 [41] LIN Y L, COOPER C, WANG M, et al. Handwritten, soft circuit boards and antennas using liquid metal nanoparticles[J]. Small, 2015, 11(48): 6397-6403. doi: 10.1002/smll.201502692 [42] 陈玉,夏鑫. 可充电电池的镓基液态金属负极材料研究进展[J]. 电源技术,2021,45(1): 132-135. doi: 10.3969/j.issn.1002-087X.2021.01.032CHEN Yu, XIA Xin. Research progress of gallium-based liquid metal anode materials for rechargeable batteries[J]. Chinese Journal of Power Sources, 2021, 45(1): 132-135. doi: 10.3969/j.issn.1002-087X.2021.01.032 [43] DESHPANDE R D, LI J C, CHENG Y T, et al. Liquid metal alloys as self-healing negative electrodes for lithium ion batteries[J]. Journal of the Electrochemical Society, 2011, 158(8): A845.1-A845.5. doi: 10.1149/1.3591094 [44] 陈玉,夏鑫. 锂离子电池液态GaSn自修复负极材料的制备及其电化学性能[J]. 纺织学报,2021,42(6): 57-62.CHEN Yu, XIA Xin. Preparation and electrochemical properties of liquid GaSn self-repairing anode materials for lithium-ion batteries[J]. Journal of Textile Research, 2021, 42(6): 57-62. [45] XING Z R, FU J H, CHEN S, et al. Perspective on gallium-based room temperature liquid metal batteries[J]. Frontiers in Energy, 2022, 16(1): 23-48. doi: 10.1007/s11708-022-0815-y [46] LIU D Y, SU L S, LIAO J H, et al. Rechargeable soft-matter EGaIn-MnO2 battery for stretchable electronics[J]. Advanced Energy Materials, 2019, 9(46): 1902798.1-1902798.12. [47] WANG Y S, WANG X S, XUE M Q, et al. All-in-one ENERGISER design: smart liquid metal-air battery[J]. Chemical Engineering Journal, 2021, 409: 128160.1-128160.12. [48] HUANG C H, ZONG J J, WANG X D, et al. Production of uniformly sized gallium-based liquid alloy nanodroplets via ultrasonic method and their Li-ion storage[J]. Materials, 2021, 14(7): 1759.1-1759.11. [49] DING Y, GUO X L, QIAN Y M, et al. Room-temperature all-liquid-metal batteries based on fusible alloys with regulated interfacial chemistry and wetting[J]. Advanced Materials, 2020, 32(30): 2002577.1-2002577.8. [50] WANG D L, LIN Z H, ZHOU C, et al. Liquid metal gallium micromachines speed up in confining channels[J]. Advanced Intelligent Systems, 2019, 1(7): 1900064.1-1900064.6. [51] TANG S Y, LIN Y L, JOSHIPURA I D, et al. Steering liquid metal flow in microchannels using low voltages[J]. Lab on a Chip, 2015, 15(19): 3905-3911. doi: 10.1039/C5LC00742A [52] XIE J E, LI F X, KUANG S L, et al. Modeling and motion control of a liquid metal droplet in a fluidic channel[J]. ASME Transactions on Mechatronics, 2020, 25(2): 942-950. doi: 10.1109/TMECH.2020.2964387 [53] LIU M, WANG Y X, KUAI Y B, et al. Magnetically powered shape-transformable liquid metal micromotors[J]. Small, 2019, 15(52): 1905446.1-1905446.7. [54] 王二龙. 受限液态金属电驱动器研究[D]. 合肥: 中国科学技术大学, 2021. [55] 易仁义. 液态金属磁流体发电机数值模拟与特性分析[D]. 济南: 山东大学, 2021. [56] COSOROABA E, CAICEDO C, MAHARJAN L, et al. 3D multiphysics simulation and analysis of a low temperature liquid metal magnetohydrodynamic power generator prototype[J]. Sustainable Energy Technologies and Assessments, 2019, 35: 180-188. doi: 10.1016/j.seta.2019.05.012 [57] YAMAGUCHI H, NIU X D, ZHANG X R. Investigation on a low-melting-point gallium alloy MHD power generator[J]. International Journal of Energy Research, 2011, 35(3): 209-220. doi: 10.1002/er.1685 [58] NIU X D, YAMAGUCHI H, YE X J, et al. Characteristics of a MHD power generator using a low-melting-point Gallium alloy[J]. Electrical Engineering, 2014, 96(1): 37-43. doi: 10.1007/s00202-012-0275-1 [59] 刘艳娇, 彭燕, 赵凌志. 往复式液态金属磁流体发电机中磁流体流动的三维数值模拟[C]//第四届中国海洋可再生能源发展年会暨论坛论文集. 北京: 海洋出版社, 2015: 329-342. [60] GAO Y X, LIU J. Gallium-based thermal interface material with high compliance and wettability[J]. Applied Physics A: Materials Science and Processing, 2012, 107(3): 701-708. doi: 10.1007/s00339-012-6887-5 [61] LIU H, LIU H Q, LIN Z Y, et al. AlN/Ga-based liquid metal/PDMS ternary thermal grease for heat dissipation in electronic devices[J]. Rare Metal Materials and Engineering, 2018, 47(9): 2668-2674. doi: 10.1016/S1875-5372(18)30207-8 [62] JI Y L, YAN H L, XIAO X, et al. Excellent thermal performance of gallium-based liquid metal alloy as thermal interface material between aluminum substrates[J]. Applied Thermal Engineering, 2020, 166: 114649.1-114649.8. [63] 牛波. 基于液态金属的各向异性导热薄膜的研究与应用[D]. 北京: 中国科学院大学, 2015. [64] MA C F, SHEN J, TAN L M, et al. Study on thermal reliability of Ga-based liquid metal as thermal interface material encapsulated with fluororubber[J]. Journal of Electronic Materials, 2022, 51(12): 6975-6985. doi: 10.1007/s11664-022-09927-7 [65] LIN Z Y, LIU H Q, LI Q G, et al. High thermal conductivity liquid metal pad for heat dissipation in electronic devices[J]. Applied Physics A, 2018, 124(5): 368.1-368.6. [66] WEI S, YU Z F, ZHOU L J, et al. Investigation on enhancing the thermal conductance of gallium-based thermal interface materials using chromium-coated diamond particles[J]. Journal of Materials Science: Materials in Electronics, 2019, 30(7): 7194-7202. doi: 10.1007/s10854-019-01038-0 [67] ZENG C Z, MA C F, SHEN J. High thermal conductivity in diamond induced carbon fiber-liquid metal mixtures[J]. Composites Part B: Engineering, 2022, 238: 109902.1-109902.12. [68] XING W K, WANG H, CHEN S, et al. Gallium-based liquid metal composites with enhanced thermal and electrical performance enabled by structural engineering of filler[J]. Advanced Engineering Materials, 2022, 24(9): 2101678.1-2101678.8. [69] KI S, SHIM J, OH S, et al. Gallium-based liquid metal alloy incorporating oxide-free copper nanoparticle clusters for high-performance thermal interface materials[J]. International Journal of Heat and Mass Transfer, 2021, 170: 121012.1-121012.11. [70] KHAN Y, SAROWAR M T, MOBARRAT M, et al. Performance comparison of a microchannel heat sink using different nano-liquid metal fluid coolant: a numerical study[J]. Journal of Thermal Science and Engineering Applications, 2022, 14(9): 091014.1-091014.13. [71] KONG W, WANG Z Y, WANG M, et al. Oxide-mediated formation of chemically stable tungsten–liquid metal mixtures for enhanced thermal interfaces[J]. Advanced Materials, 2019, 31(44): 1904309.1-1904309.8. [72] TAWK M, AVENAS Y, KEDOUS-LEBOUC A, et al. Numerical and experimental investigations of the thermal management of power electronics with liquid metal mini-channel coolers[J]. IEEE Transactions on Industry Applications, 2013, 49(3): 1421-1429. doi: 10.1109/TIA.2013.2252132 [73] 李思琪,韩秋漪,荆忠,等. 高功率密度紫外LED光源模块的液态金属散热系统[J]. 中国照明电器,2019(4): 1-9.LI Siqi, HAN Qiuyi, JING Zhong, et al. A liquid metal cooling system for high power density UV-LED module[J]. China Light & Lighting, 2019(4): 1-9. [74] 王德辉. 应用液态金属的换流阀散热技术研究[D]. 北京: 华北电力大学, 2017. [75] 李振明,刘伟,赵勇青,等. 基于液态金属的高热流密度电力设备冷却实验研究[J]. 电工电能新技术,2017,36(4): 66-70.LI Zhenming, LIU Wei, ZHAO Yongqing, et al. Experimental study on cooling electric equipment with high heat flux based on liquid metal[J]. Advanced Technology of Electrical Engineering and Energy, 2017, 36(4): 66-70. [76] 李骜,徐太栋. 镓基液态金属Ga80In20在雷达冷板散热中的数值模拟研究[J]. 雷达与对抗,2021,41(3): 46-49.LI Ao, XU Taidong. Numerical simulation of Gallium-based liquid metal Ga80In20 in heat dissipation of radar cold plate[J]. Radar & ECM, 2021, 41(3): 46-49. [77] DOBOSZ A, BERENT K, BIGOS A, et al. Interfacial phenomena between liquid alloy and Ni substrate covered by Ni-W layer[J]. Materials Letters, 2020, 277: 128299.1-128299.4. [78] 程勇,郭延龙,何志祝,等. 相变散热技术在小型高效半导体抽运激光器中的应用研究[J]. 中国激光,2016,43(1): 39-45.CHENG Yong, GUO Yanlong, HE Zhizhu, et al. Application research of phase change material heat removal technology for compact high efficiency diode pumped laser[J]. Chinese Journal of Lasers, 2016, 43(1): 39-45. [79] GE H S, LIU J. Keeping smartphones cool with gallium phase change material[J]. Journal of Heat Transfer, 2013, 135(5): 054503.1-054503.5. [80] ZHENG J S, LI X X, XING W K, et al. Paste-like recyclable Ga liquid metal phase change composites loaded with miscible Ga2O3 particles for transient cooling of portable electronics[J]. Applied Thermal Engineering, 2022, 213: 118766.1-118766.10. [81] GUO J, CHENG J, TAN H, et al. Ga-based liquid metal: a novel current-carrying lubricant[J]. Tribology International, 2019, 135: 457-462. doi: 10.1016/j.triboint.2019.03.039 [82] BURTON R G, BURTON R A. Gallium alloy as lubricant for high current density brushes[J]. IEEE Transactions on Components, Hybrids, and Manufacturing Technology, 1988, 11(1): 112-115. doi: 10.1109/33.2973 [83] BAI P P, LI S W, JIA W P, et al. Environmental atmosphere effect on lubrication performance of gallium-based liquid metal[J]. Tribology International, 2020, 141: 105904.1-105904.7. [84] BUCKLEY D H, JOHNSON R L. Gallium-rich films as boundary lubricants in air and in vacuum to 10−9 mm Hg[J]. A S L E Transactions, 1963, 6(1): 1-11. doi: 10.1080/05698196308971993 [85] 程军,于源,朱圣宇,等. 多功能室温液态金属在不同摩擦副条件下的润滑性能研究[J]. 摩擦学学报,2017,37(4): 435-441.CHENG Jun, YU Yuan, ZHU Shengyu, et al. Lubrication characteristics of multifunctional liquid-state metal materials under different sliding-pairs[J]. Tribology, 2017, 37(4): 435-441. [86] 于源,乔竹辉,徐铁伟,等. 镓基液态金属用作润滑剂的研究现状[J]. 铸造技术,2022,43(6): 401-409. doi: 10.16410/j.issn1000-8365.2022.06.002YU Yuan, QIAO Zhuhui, XU Tiewei, et al. Research progress of gallium-based liquid metals as lubricant[J]. Foundry Technology, 2022, 43(6): 401-409. doi: 10.16410/j.issn1000-8365.2022.06.002 [87] LI H J, TIAN P Y, LU H Y, et al. State-of-the-art of extreme pressure lubrication realized with the high thermal diffusivity of liquid metal[J]. ACS Applied Materials & Interfaces, 2017, 9(6): 5638-5644. [88] YANG D S, CHEN W Y, CHEN J, et al. Ga-based liquid metal as an extreme pressure lubricant for steel-ceramic pairs[J]. Science China Technological Sciences, 2022, 65(5): 1107-1115. doi: 10.1007/s11431-021-2015-x [89] HE B L, LIU S, ZHAO X Y, et al. Dialkyl dithiophosphate-functionalized gallium-based liquid-metal nanodroplets as lubricant additives for antiwear and friction reduction[J]. ACS Applied Nano Materials, 2020, 3(10): 10115-10122. doi: 10.1021/acsanm.0c02092 [90] LI X, YAN C, LIU Q, et al. An in situ fabrication of CuGa2 film on copper surface with improved tribological properties[J]. Journal of Tribology, 2021, 143(7): 071404.1-071404.7. [91] LI X, WANG Z K, DONG G N. Preparation of nanoscale liquid metal droplet wrapped with chitosan and its tribological properties as water-based lubricant additive[J]. Tribology International, 2020, 148: 106349.1-106349.9. [92] HE B L, WANG P, LU Q, et al. Zwitterionic microgel-functionalized gallium-based liquid-metal nanodroplets as aqueous lubricant additives[J]. Tribology International, 2023, 177: 107952.1-107952.9. [93] LI X, QI P H, LIU Q, et al. Improving tribological behaviors of gallium-based liquid metal by h-BN nano-additive[J]. Wear, 2021, 484/485: 203852.1-203852.7. [94] MA J Q, LIU C, CHEN W Y, et al. Improving the lubricating performance of Ga-based liquid metal doped by silver[J]. Tribology International, 2022, 171: 107520.1-107520.11. [95] LI X, LI Y H, TONG Z, et al. Enhanced lubrication effect of gallium-based liquid metal with laser textured surface[J]. Tribology International, 2019, 129: 407-415. doi: 10.1016/j.triboint.2018.08.037