Enhancement of the wettability and solder joint reliability at the Sn–9Zn–0.5Ag lead-free solder alloy–Cu interface by Ag precoating

The enhancement of the wettability and solder joint reliability at the Sn–9Zn–0.5Ag solder alloy–Cu interface by Ag precoating has been investigated. The wettability of the Sn–9Zn–0.5Ag solder alloy–Cu interface has been improved by Ag precoating. The adhesion strength of the solder alloy–Ag precoated Cu interface increases from 4.11±0.56 to 6.92±0.85 MPa as dipped at 250 °C for 10 s. When the dipping time is prolonged from 10 to 30 s, the interfacial adhesion strength increases from 6.92±0.85 to 13.62±0.73 MPa. The interfacial adhesion strength is enhanced by the rod-like Cu–Zn intermetallic compound (IMC) formed close to the interface. The diffusion coefficients of Sn and Zn in the IMC layer are determined as 5.76×10⁻¹⁰ and 9.50×10⁻¹¹ cm²/s at the Sn–9Zn–0.5Ag–Cu and Sn–9Zn–0.5Ag–Ag precoated Cu interfaces, respectively.     

金属/陶瓷润湿性(下)

本文综述了金属／陶瓷的润湿性的表征及测定方法，理论研究方法，改善润湿性的技术方法。并系统收集和评价了各种金属／陶瓷体系中润湿性的测试和研究结果。     

动态毛吸法测定纤维浸润性

动态毛吸法测定纤维浸润性还存在着一些问题；如水力常数Ｋ及空隙率ε的选取，接触角θ的求取方法等。研究发现Ｋ＝３．３不是一普适常数。浸润仪测试的实验数据使用Ｗａｓｈｂｕｒｎ方程处理为宜，本文计算了几种液体对玻璃纤维的接触角。同时还提供了一种估算纤维束中等效毛织管半径及分布的方法。     

A New Method of Studying Surface Activity for Liquid Alloys

ＡＮｅｗＭｅｔｈｏｄｏｆＳｔｕｄｙｉｎｇＳｕｒｆａｃｅＡｃｔｉｖｉｔｙｆｏｒＬｉｑｕｉｄＡｌｏｙｓ①②ＹＡＮＧＹｏｎｇｚｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄｐｈｙｓｉｃｓ，ＮｏｒｔｈｗｅｓｔｅｒｎＰｏｌｙｔｅｃｈｎｉｃａｌＵｎｉｖｅｒｓｉ...     

表面活性剂润湿力的测定方法探讨

通过测定原棉布圆片从浸没于一定浓度的表面活性剂溶液开始至沉降所需的时间,以表示该表面活性剂的润湿力,参照采用ISO8022-84,对测试方法进行了探讨和研究,认为这种测定方法对于产品的开发及染整、洗染行业的应用是特别有效的。     

玻璃与氧化膜浸润性研究

通过理论计算和实验研究了浸润性的两个评价指标接触角θ与铺展面积Ｓ之间的关系及其最佳适用范围。在此基础上，研究了封接条件和氧化膜结构对玻璃与氧化膜浸膜性的影响。     

液态金属表面特性研究的新途径

以流体动力学方程和光栅衍射原理为基础，得到了研究液态金属表面特性的理论方程式。在液态金属的表面上，激振出了理想的一维表面张力驻波，交视作为一种反射式光栅；研制成能自动地采集光信息与处理数据的系统，它由电荷耦合器件、驱动电路、模数转换及计算机所需的硬、软件组成，从而提供了测试分析液态金属表面特性的新途径。     

Surface properties of LB monolayers composed of aminimide derivatives having two alkyl chains

Langmuir-Blodgett monolayers were prepared using a series of aminimide derivatives having two alkyl chains. One of the alkyl chains had 19 carbons, while the number of the other alkyl chain was systematically changed from 8 to 20. Molecular organization of the aminimides on the water surface reflected the length of alkyl chains. Inter-chain packing and conformational order of the alkyl chains in the monolayer were affected by the length of the two alkyl chains. Steric and dynamic contact angles of a series of aprotic liquid having low surface tension were measured to investigate surface properties of the films with varying molecular organization of alkyl tail groups. Fluid-like monolayers having molecularly rough surface indicated high wettabilities for both of n-alkanes and naphthalene derivatives. However, contact angle hyteresis on the monolayer was sensitive to the sort of probe liquids owing to the interaction between the uppermost portion of the alkyl chains aligned homeotropically on the fluid-like monolayers. In contrast, the monolayer containing well-ordered, well-packed alkyl chains indicated low wettabilities, small hysteresis and random orientation of liquid crystals.     

Coal petrology characteristics of middlings from Qianjiaying fat coal mine

The objective of this paper is to evaluate the coal petrology characteristics of slack middlings (13–0.5 mm) of dense media separation and flotation middlings from Qianjiaying fat coal preparation plant. Phase composition, macerals distribution, microlithotype and mineral occurrence of the two middlings were studied by XRD analysis and polarized light microscopy observation. Macerals distribution and wettability of the float-and-sink products separated from the middlings after grinding was investigated to determine the liberation degree. Studies show that there are more vitrinite and mineral, but less inertinite in slack middlings than in flotation middlings. Macerals associated with mineral in slack middlings is 69.85%, by volume, which is 17.86% higher than that in flotation middlings. Minerals in slack middlings are dominated by pyrite and clay, which are disseminated with the diameter less than 2 μm. The main mineral in flotation middlings is clay with size range of 2–20 μm. Single macerals in the slack middlings are difficult to liberate due to the fine-grained minerals. After grinding, macerals associated with minerals in the slack middlings decrease to 46.73%, by volume, which is higher than in flotation middlings by 25.89%, by volume. For slack middlings with poor liberation degree, density fractions below 1.8 g/cm³ is hydrophobic with contact angle above 71.5°. For the well liberated flotation middlings, there is significant wettability difference among the float-and-sink products. This research is the theoretical basis to realize re-separation of middlings.     

云母对消失模铸造涂料浸润性的影响

分析了消失模铸造工艺特点，指出泡沫塑料模样液化产物与涂料层间良好的润湿性对其通过涂层排出是有利的。研究了云母对消失模铸造涂料的涂挂性以及涂料层对泡沫塑料模样液化产物浸润性能的影响。结果表明：云母有助于改善涂料的涂挂性能，但对泡沫塑料模液化产物的排除是不利的。