Enhanced wetting of dual-phase metallic solids by liquid metals: A new effect of interfacial reaction

The wetting of Cu–Fe two-phase composites by molten Sn is studied by the sessile drop technique under high vacuum at 400 °C. In this system Sn reacts with both solid components, forming intermetallic compounds. It is found that the curve of contact angle vs. the surface fraction of components passes through a minimum, behaviour that cannot be interpreted by existing models describing wetting of heterogeneous surfaces and/or reactive wetting. It is shown that the observed enhanced wetting can be explained by the dissolution contrast of Cu and Fe phases, leading to interfacial microroughness, thus providing an additional driving force for wetting. In order to take into account this new effect of interfacial reactions on wettability, an equation similar to Wenzel’s equation is established. It is shown that this equation can explain the change in wettability of composites when Sn is replaced by SnPb eutectic presenting a lower reactivity than pure Sn, as well as the effect on wettability observed when the scale of composite microstructure is changed with the surface fraction of components remaining constant.     

Al-Mg合金对2D石墨纤维网的润湿性及铺展速率分析

本文使用静滴法研究了不同Mg含量(3.2, 4.5, 6.5, 8.5, 10, 13, 17 wt.% Mg)的Al-Mg合金在M40石墨纤维网上的润湿行为,重点讨论了Mg元素含量对润湿性及铺展速率的影响。 随着Al-Mg合金中的Mg含量从3.2 wt.%增加至17 wt.%,初始润湿角从115o降低到88.5o,而最终润湿角则由 96.7o降低到71o。由于M40石墨纤维的表面组织性质与普通石墨有较大的区别,因此与高密度碳平板相比,Al-Mg合金在石墨纤维网上的初始润湿角更小。而润湿角随Mg含量的增加而减小主要是源于Mg含量的增加可以显著降低Al-Mg合金的表面张力。基于Dezellus方程,进一步计算了Al-Mg合金在石墨纤维网上的铺展速率,计算结果与实验结果基本吻合。基于Miedema模型计算得到的铺展速率系数k也与实验结果基本吻合,此结果证明了Miedema模型在铺展速率计算方面应用的合理性。计算与实验结果均表明Mg元素含量的增加虽然可以显著降低润湿角,但对铺展速率影响不大。     

The role of intermetallics in wetting in metallic systems

Formation of intermetallic seems to improve strongly wetting of a solid metal by a liquid one. The aim of this study is to identify the reasons of this improvement. For this purpose, wetting of Fe is determined at the same experimental conditions for two liquid metals, one reactive (Sn), the other non-reactive (Pb).     

Wettability of molten Zr55Cu30Al10Ni5 on alumina and zirconia

The wetting behavior of molten Zr55Cu30Al10Ni5 on Al2O3 and ZrO2 was studied using the sessile drop method. The results show that the nonwetting-to-wetting transition for the Zr55Cu30Al10Ni5/ZrO2 wetting system takes place at 1193 K. The wetting of molten Zr55Cu30Al10Ni5 on Al2O3 is a non-reactive wetting. Owing to the formation of diffusion band at the front of the wetting tip in the Zr55Cu30Al10Ni5/Al2O3 system, the wettability of Al2O3 is better than that of ZrO2.     

Ce及Mg对SiCp/Al复合材料界面润湿性的影响

采用液态搅拌法制备了SiCp/ZL105复合材料,并对其界面行为进行了研究.试验结果表明,表面活性元素Mg的加入能降低铝合金熔体的表面张力,进而改善SiC颗粒与铝基体间的界面润湿性,增强SiC颗粒与基体间的浸润复合;而加入富铈混合稀土后没有收到明显的效果.分析认为,Mg对铝液表面张力及其在颗粒表面润湿性的改善是通过在颗粒与熔体间引发了化学反应达到的,并非仅物理作用.在本试验条件下,Mg的加入引发了MgAl2O4在颗粒表面的生成,达到了改善界面润湿性的效果;而富铈稀土加入后,未在SiC颗粒与铝熔体间引发界面反应.     

化学刻蚀制备亲水性铝及润湿性变化规律

目的通过化学刻蚀的方法制备具有亲水性的纯铝与高纯铝表面,在室温下进行时效,分析润湿性随时效时间的变化规律。方法实验以2 mol/L浓度的盐酸进行刻蚀,将试样分别刻蚀4、8、12、16、20 min,吹干制备好的试样。利用OCA15EC接触角测量仪测定润湿角,将试样放置在室温下进行时效,并记录时效后的润湿角,分析润湿角变化的规律;采用场发射扫描电子显微镜观察试样表面的微观形貌,结合Wenzel理论与Cassie理论分析润湿角变化的原因;对试样进行EDS分析,分析时效后试样所含元素含量的变化情况,阐述润湿性变化的机理。结果不同刻蚀时间制备的样品润湿角存在差异,经过室温时效,润湿角呈现增大的趋势。结论纯铝在刻蚀时间16 min时能够获得超亲水的表面,在室温下时效5天能维持润湿角在20°以下。高纯铝在刻蚀时间为12 min时能够获得超亲水表面,经过5天的室温时效,12 min刻蚀的样品润湿性保持得较为稳定,润湿角维持在12°以下,其他刻蚀时间的样品亲水性及稳定性略差。     

Effect of Trace O Element on High-temperature Wettability Between Ni_3Al Melt and Y_2O_3 Ceramic

Effect of trace O element on the high-temperature wettability between Ni_3Al scrap melt and Y_2O_3 ceramic at 1873 K is investigated. With the increase in O content in Ni_3Al scrap melt from 6 to 21 ppm, the equilibrium contact angle decreases from 93.3° to 88.9°. The initial surface tension and adhesive work of molten Ni_3Al scrap drop from 3153.5 to 807.4 mN m~(-1) and from 2974.6 to 882.2 mN m~(-1), respectively. The average spreading rate increases from 0.03° s~(-1) to 0.17° s~(-1). The whole wetting processes are divided into four periods. The main driving force for spreading in period(1) is the adsorption and diffusion of active atoms around the interface. Trace O content in Ni_3Al scrap has a significant impact on interfacial reactions which mostly take place in the second stage, and can accelerate the spreading process on Y_2O_3 substrate. The reaction products during wetting process are Y_3Al_5O_(12), YAlO_3 and Al_2O_3.     

ZnO-Al_2O_3-B_2O_3-SiO_2系微晶玻璃与可伐合金的润湿性能

研制了一种新型的与可伐熔封的ZnO-Al_2O_3-B_2O_3-SiO_2系微晶玻璃,研究了不同工艺条件下微晶玻璃与可伐合金间的润湿角大小,结果表明,熔封气氛和熔封温度对润湿性能影响很大,熔封时间影响最小.采用最佳的工艺条件,其润湿性能与现有的其它玻璃润湿性能相似.同时发现玻璃与可伐合金间的润湿角保持在10°～30°之间能得到质量良好的熔封产品.在基本不改变传统工艺制度的条件下,可完成锌铝硼硅系微晶玻璃与可伐合金的熔封,即利用排蜡过程同时完成微晶玻璃的形核,熔封后在稍低温度保温或减慢冷却速度可以完成微晶玻璃的结晶过程.锌铝硼硅系微晶玻璃与预氧化可伐合金的封接依靠玻璃中的SiO_2与FeO或Fe_3O4发生界面反应形成牢固的结合.     

Wetting, adhesion and diffusion in Cu–Al/SiO2 system at 1473 K

Sessile-drop wetting experiments and interfacial microstructure examinations show that at high temperature, Cu alloyed with Al mildly promotes the wettability, yet fails to enhance the adhesion and impede the thermal diffusion between Cu and SiO₂, in contrast to the behavior observed in low-temperature annealing studies.     

冷金属过渡下熔融铝合金在钢板上润湿铺展的数值模拟

采用Fluent软件对冷金属过渡条件下第一个周期内熔融铝合金在Q235钢板上润湿及凝固进行了分析和研究,得出温度场对金属凝固的影响和两者对熔滴润湿铺展能力的影响,以及不同初始参数对熔融铝合金在Q235钢板表面润湿行为的影响.结果表明,熔融铝合金首先在三相线处开始凝固,这与温度场的分布相一致;已凝固的金属对熔融铝合金的铺展起到一定的阻碍作用;随着初始温度的增加湘线附近局部凝固的固柏体减小,熔融铝合金在Q235钢板上表现出好的润湿性.