均匀金属微滴打印大高径比金属针肋及其形貌预测

Slender Needle Rib Printing with Uniform Metal Droplets and the Morphology Prediction

散热器是航天器热控系统的核心部件,采用金属微针肋阵列结构的散热器具有优良性能,能够极大提升散热效率。但微小金属针肋结构有大长径比、弱刚度的特点,切削或铸造等传统成形方法存在切削受力变形、难以填充型腔或脱模等不利因素,使得微针肋阵列高径比受到制约。本文提出均匀金属微滴3D打印直接成形大高径比金属微针肋方法,研究了基板温度、液滴沉积温度与液滴最终形貌的关系,建立了沉积液滴形貌以及微针肋轮廓预测模型,实现了针肋形貌的预测。在相应参数下以锡铅合金为材料进行了微滴打印试验,打印出直径为394μm、高径比超过100的金属微针肋,为将来航天器用高效微针肋散热器的3D打印新途径奠定了基础。

Radiator is the core component in spacecraft thermal control system.The radiator with the array structure of micro metal needle ribs have excellent performance,and can greatly improve the efficiency of heat dissipation.However,the micro metal needle ribs in radiators have the structures with the characteristics of large aspect ratio and weak stiffness,which make them hard to be manufactured by conventional forming methods such as cutting and casting because of the restriction on the aspect ratio of micro needle rib array due to the disadvantageous factors in the conventional forming methods such as cutting force deformation and difficulty in filling the cavity or demoulding.In the present paper,a 3D printing method with uniform metal droplets is proposed to directly print metal needle ribs with large aspect ratio.The relationships among the substrate temperature,the droplet deposition temperature,and the final droplet morphology are studied,a theoretical model for predicting the morphology of deposited droplets and micro needle ribs is established,and the prediction of needle rib morphology is realized.The experimental results agree well with the predicted ones,which confirms the feasibility of the prediction method.With proper experiment parameters,slender needle ribs with a diameter of 394μm and an aspect ratio over 100 are successfully printed by Sn-Pb alloy droplets.The research will lay a foundation for the development of novel 3D printing technology of manufacturing high efficiency micro needle rib radiators in future aerospace applications.