非均匀基底上的锡钎料反应润湿

IMR OpenIR

	非均匀基底上的锡钎料反应润湿
	赖庆全
学位类型	硕士
导师	尚建库 ; 张磊
	2011
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	材料学
关键词	反应润湿非均匀基底复相合金多孔材料锡钎料 Reactive Wetting Heterogeneous Substrates Dual-phase Alloy Porous Materials Sn-based Solder
摘要	"高温环境下液态金属对固体表面的润湿，尤其是反应润湿，是粉末冶金、金属基复合材料和陶瓷连接等工业技术的基础。对反应润湿的认识已积累了大量的成果，并发展出被广泛接受的反应产物控制（reaction product control, RPC）模型。然而，已有的认识主要针对简单的均相基底。本论文通过研究两类非均匀基底，包括复相合金以及表面多孔层上的锡钎料反应润湿，探求在非均匀基底上的反应润湿机理。研究发现，锡钎料对复相铜铁和铜钴合金的润湿性优异，可以分别优于均相纯组元基底的润湿性。在复相合金上的润湿性不随Cassie公式所描述的各相润湿性的配分机械加和变化，接触角随面积分数变化曲线显现“V”形特点，即润湿性最优的情况出现于合适分数的两相复合。锡铅共晶钎料在纯铁和纯铜上的接触角均小于纯锡，但锡铅共晶钎料在铜铁双相合金上的接触角大于纯锡。在复相组织上，钎料的接触角与相界密度之间存在反向变化关系。于润湿前沿观察到液体沿着相界优先迁移和Cu/Fe相界沟槽的结构特征。锡钎料在复相合金上的优异润湿性，来源于界面冶金反应时两相在液态金属中的溶解速率差，由此造成接触线处相界沟槽并增加了润湿驱动力。复相合金上钎料的润湿前沿也表现出不均匀的特征。在Sn/CuFe体系的润湿前沿，富铜相网络上覆盖着冶金反应生成的化合物，而富铁相表面也已通过反应生成一层薄化合物。锡主要分布在富铜相网络上，但润湿前沿的形貌表明液态锡同时润湿富铜相和富铁相，而不是优先沿铜网络润湿。作为对润湿前沿形貌形成的模拟，薄镀锡层回流后发生退润湿，其形貌与润湿前沿相似。Sn/Cu和Sn/Fe体系反应活性的差别会造成液体薄膜退润湿，这是润湿前沿形貌的重要形成原因。在反应润湿体系中，多孔表面上的润湿受界面冶金反应和渗透的控制。液态纯锡在铜微孔层上的润湿性取决于温度、孔径和孔隙率。在一定的温度和多孔体结构参数中，冶金反应产物会导致通孔闭合并阻碍渗透的进行，从而影响润湿。"
其他摘要	"Wetting, especially reactive wetting by liquid metals, of solids at high temperatures, is important to many technologies, such as powder metallurgy, metal-matrix composites and ceramics connecting. Interpretation of reactive wetting has been built on a lot of works, and a widely-accepted reaction product control (RPC) model has been developed. However, the previous understanding mainly involved homogeneous substrates. This thesis investigated reactive wetting of heterogeneous substrates, including dual-phase and porous substrates, by Sn-based solders, to clarify the wetting mechanism of these systems. It is found that, the wettability of dual-phase CuFe and CuCo alloys is excellent and better than that of each component. Reactive wetting on dual-phase alloys doesn’t follow the law described by Cassie equation that wettability on dual-phase surface depends on the weight average of wettability of each phase. Instead, the contact angle vs. area fraction of Cu showed a “V”-shape variation. While the contact angles of SnPb eutectic solder on Cu and Fe were smaller than Sn, they were larger on CuFe alloys. On the dual-phase microstructure, there was an inverse relationship between the contact angle and the phase boundary density. From the observations of wetting along phase boundaries and phase boundary grooving at the wetting front, it was shown that the excellent wettability of dual-phase alloys resulted from the sharp difference in the dissolution rate between the two phases, which promotes phase boundary grooving at the triple junction and enhances wetting. Wetting front of the liquid solder on dual-phase alloys was heterogeneous. At the wetting front of Sn/CuFe systems, the Cu network was covered by reaction product, so was the Fe-rich phase. Although Sn was distributed mainly on Cu-rich phase, liquid Sn wetted both Cu-rich and Fe-rich phases, not selectively along Cu network. As a simulation of the morphology evolution of wetting front, a thin Sn film was electroplated on the alloy substrate; upon dewetting after reflow, the morphology of the dewetting film resembled that of the wetting front. It was suggested that the difference in the reactivity between Sn/Cu and Sn/Fe systems was responsible for the dewetting of liquid film and for the morphology of the wetting front. In reactive systems, wetting on porous surface is controlled by interfacial metallurgical reaction and infiltration. Wettability of microporous Cu layer was found to depend on temperature, pore size and porosity. For some porous structures at a suitable temperature, reaction product may close the pores and block the infiltration, limiting wetting."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64385
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	赖庆全. 非均匀基底上的锡钎料反应润湿[D]. 北京. 中国科学院金属研究所,2011.