高性能反重力热管变截面复合吸液芯优化设计与烧结成形机理研究

With the increasing heat flux and limited cooling space of highly integrated chip in the field of microelectronics and photoelectron, the problem of thermal control is very severe. It is difficult to satisfy the radiating demand due to low capillary in grooved heat pipe and high resistance of liquid reflux in sintered heat pipe. In this project, A kind of composite wick with variable cross-section, which was sintered by ordered copper fiber with rough structure on surface and copper powder with different mesh, was used in the inner wall of heat pipe to achieve excellent heat transfer performance under the anti-gravity conditions. Based on the digital characterization to multi-scale and micro-pore structure of copper fiber and powder sintered, theoretical model of capillary pressure and reflow resistance of composite wick with variable cross-section in heat pipe was set up. Surface parameters of composite wick were designed with the goal of heat transfer performance. Cutting process parameters were studied to obtain the rough surface structure according to demand. The bonding mechanism of copper fiber and powder in heat pipe and the affect on core features of composite wick with variable cross-section structure by multi-parameter matching of the sintering process were revealed. According to the law of heat transfer under the effect of micro-scale structures, parameters of wick in heat pipe under the anti-gravity conditions were optimized by experimental method to receive the better heat transfer performance. This project will not only provide the independent intellectual property rights in the manufacturing technology of thermal control elements under the anti-gravity conditions, but also improve the theory research level of phase change heat transfer components.

随着微/光电子领域高集成度芯片热流密度不断增加和散热空间条件的局限，其热控制问题愈加严峻。针对沟槽式毛细压力低和烧结式液体回流阻力大已难以满足反重力条件传热需求的现状，本项目提出将表面具有粗糙结构的铜纤维有序排列与铜粉烧结变截面复合吸液芯应用于热管内壁实现反重力条件下优良的传热性能。在对烧结形成的多尺度微孔隙结构表征的基础上，建立热管变截面复合吸液芯毛细压力与回流阻力理论模型，以传热性能为目标设计吸液芯气液界面曲面参数；研究铜纤维粗糙表面按需协同生成的切削工艺参数，揭示铜纤维和铜粉在热管内壁黏合成形机理及烧结工艺多参数匹配对吸液芯核心特征的影响机制；探索变截面复合吸液芯微尺度结构作用下的传热规律，通过实验对反重力热管吸液芯参数进行对比优化获得最佳传热性能。本项目的研究对建立拥有自主知识产权的反重力热控制元件设计制造理论体系以及对提高我国高性能相变传热器件的理论研究水平具有重要意义。

随着微/光电子领域高集成度芯片热流密度不断增加和散热空间条件的局限，其热控制问题愈加严峻。针对沟槽式毛细压力低和烧结式液体回流阻力大已难以满足反重力条件传热需求的现状，本项目提出将表面具有粗糙结构的铜纤维有序排列与铜粉烧结变截面复合吸液芯应用于热管内壁实现反重力条件下优良的传热性能。通过SEM观察确定了铜纤维多孔结构的合适烧结温度为1100℃-1200℃，烧结时间为60分钟。采用液滴法研究纤维－粉末复合吸液芯结构的润湿性能。在纤维基体上烧结不同粒径的粉末，粒径为75-106μm的复合多孔结构润湿性能较好。通过实验测试得到了复合吸液芯的最佳制造参数为烧结粒径为75-106μm的粉末，烧结温度为1200℃，烧结时间为60min。通过加工过程分析，发现在利用多齿刀具进行有效分纤的条件下，在0.08mm-0.18mm的背吃刀量、5.25m/min-14.71m/min范围的切削速度、0.1mm/r-0.2mm/r进给速度的条件下，纤维表面容易形成一系列的微翅结构。制作了具有均匀截面吸液芯、钝圆锥吸液芯以及尖圆锥吸液芯的热管并通过实验研究其在正常工作位置及反重力放置条件下的传热性能。发现钝圆锥空腔热管在反重力测试条件下传热能力最好，且钝圆锥空腔热管的加热块温度在反重力测试条件与正常测试条件下的温度几乎一致，表明钝圆锥空腔热管的传热能力十分稳定，不受冷热源的相对位置影响，可适用于冷热源相对位置频繁切换的场合。本项目的研究对建立拥有自主知识产权的反重力热控制元件设计制造理论体系以及对提高我国高性能相变传热器件的理论研究水平具有重要意义。