锡基合金及高温熔体的润湿特性与界面行为研究

Research on the wettability and interfacial behavior of tin-based alloy and high-temperature melt under microgravity is carried out aimed at the growth field of space melt materials in the SJ10–Recoverable Scientific Experiment Satellite, which reveals the microstructure of tin-based alloy and the law of the wettability for high temperature melt. Based on the space experimental samples and the ground-based simulation experiment, the interfacial phenomena in the process of solid - liquid phase transition and tin-based alloy melting under microgravity, the relationship between the temperature and the wettability of tin- based alloy melt, copper and quartz are investigated. And the interfacial phenomena and the law of microstructure formation during solidification are also studied. Compared with the results of the ground experiment, the microscopic mechanism of the whisker growth for the solid metal surface is re-recognized. Therefore, the effective technical measures must be taken to suppress the spontaneous growth of tin whiskers, which provide basis for the protection of electronic products, especially the electronic products used in spacecraft for ensuring the reliability of long-term preservation and use. The effects of microgravity on wetting behavior and liquid / solid interface interaction between titanium-based alloy and Al2O3 were studied. Through the comparative experiment of the space and the ground, the wetting phenomenon, microscopic mechanism and the internal relationship between structure, composition and performance of tin-based alloy and high temperature melt are revealed. As a result, the theory of material science has been enriched and developed, which provides the theoretical application basis and key technical parameters for material preparation technology of the ground.

针对实践十号卫星返回式科学实验卫星的空间熔体材料生长领域，开展微重力条件下锡基合金及高温熔体的润湿特性与界面行为研究，揭示锡基合金微观结构及高温熔体的润湿规律。采用空间实验样品的测试研究与地基模拟实验相结合的技术路线，进行微重力锡基合金熔融过程中和发生固液相变时的界面现象、锡基合金熔体与铜、石英等材料的润湿性与温度关系、凝固过程的界面现象与组织形成规律及分布的研究；与地面实验结果对比基础上，重新认识固态金属表面晶须生长的微观机制，提出抑制锡晶须自发生长的有效技术措施，为保障电子产品，尤其是应用于空间飞行器的电子产品在长期保存和使用的可靠性提供依据；研究微重力对钛基合金与Al2O3之间的润湿行为、液/固界面交互作用的影响。通过天地对比研究，揭示锡基合金和高温熔体的润湿现象、微观机理和组分、结构与性能之间的内在关联，丰富和发展材料科学理论，为地面的材料制备技术提供理论应用基础和关键技术参数。

返回式科学实验卫星的空间微重力条件下，开展了微重力条件下锡基合金及高温熔体的润湿特性与界面行为研究，揭示锡基合金微观结构及高温熔体的润湿性规律。采用空间实验样品的测试研究与地基模拟实验相结合，进行了微重力锡基合金熔融过程中和发生固液相变时的界面现象、锡基合金熔体与铜、石英等材料的润湿性与温度关系、凝固过程的界面现象与组织形成规律及分布的研究；在与地面实验结果对比基础上，重新认识固态金属表面晶体生长的微观机制，提出抑制锡晶体自发生长的有效技术措施，还进行了微重力对钛基合金与Al2O3之间的润湿行为、液/固界面交互作用影响的研究。重要结果为：空间微重力下环状铜上凝固锡基合金中的气孔和元素分布以及熔体中的表面张力梯度，并对比了在微重力和正常重力条件下凝固后合金的微观结构之间的差异。Bi浓度差异引起的表面张力梯度导致在微重力条件下从熔体的右侧向左侧形成Marangoni对流。在熔体的左侧（Bi含量低），Cu浓度差异引起了从外向内的Marangoni对流。在气泡搅拌对流作用的驱动下，Cu主要从基底迁移到熔体的右侧，树突状的CuxSny沿梯度方向分布。重力引起的对流使Bi和Cu的分布均匀，减小了接触角并降低了表面张力，从而促进了合金的形核，因此，大数量密度的细小树枝状CuxSny在熔体中均匀分布。钛基合金小球放在固相Al2O3基片上加热熔化的润湿行为。将1123K下30mg的样品界面处进行线扫描，发现在界面层处Ti元素增多，而Zr元素含量呈下降趋势。液滴中的Ti元素向基片方向扩散，而同样活泼性强的Zr元素在界面处的浓度较低，浓度分布曲线具有良好的对称性。通过天地对比研究，揭示锡基合金和高温熔体的润湿现象、微观机理和组分、结构与性能之间的内在关联，丰富和发展材料科学理论，为地面的材料制备技术提供理论应用基础和关键技术参数。