材料表面润湿性的影响因素及预测模型

目的预测不同材料表面和液体之间的润湿性能。方法选取9种不同板材以及14种实验液体,采用60—1200目砂纸打磨所有平板,得到具有不同粗糙度和表面能的实验材料。利用控制变量法,分别研究了液体表面张力、固体粗糙度和固体表面能对接触角的影响。然后进行了三因素十水平的均匀设计实验,并应用SPSS软件对实验结果进行了线性分析。结果在不同液体的作用下,随着表面张力的增加,接触角不断增大,其中蒸馏水的表面张力最大,为70.13 m N/m,其在三种材料中的接触角也最大。在具有相同粗糙度的材料表面,随着表面能的增加,接触角减小,固体表面能最大(67.72 m J/m2)时,接触角达到最小值,为25.1°。在具有相同表面能的材料表面,随着粗糙度的增加,接触角呈现两种相反的趋势:当θ90°时,随着粗糙度的增加,接触角不断增大;θ90°时,随着粗糙度的增加,接触角不断减小。通过均匀设计得到了接触角的预测模型,发现液体表面张力对接触角影响的权重最大,固体表面能次之,粗糙度最小。结论通过SPSS软件拟合得到了真实材料表面接触角与其影响因素的定量关系式,针对现场管材和液体的选型进行了理论指导,从而有效降低了输送过程中的阻力损失。     

Effect of the Soldering Atmosphere on the Wettability Between Sn4.0Ag0.5Cu (in wt.%) Lead-Free Solder Paste and Various Substrates

The “degree of wetting,” which is related to the contact angle (θ) between the molten solder and the substrate, is a useful parameter on the solderability process control. The contact angle, however, is strongly dependent on the type of substrate surface finish and used atmosphere (inert or non-inert). Furthermore, the surface tension, being an important parameter on the solderability process and performance, can also be achieved if the contact angle is known. In this study, the SAC405 [Sn4.0Ag0.5Cu (in wt.%)] solder paste contact angle was measured, by the “sessile drop” method, as a function of the temperature, surface pad finish and used atmosphere. The results are discussed, and the contact angles obtained for the different conditions are compared and discussed. Then, the surface tension (experimental) was obtained from the measured contact angle and compared with the obtained by using computation models (theoretical). The experiments performed in high vacuum conditions, i.e., low oxygen content, over a temperature range, allowed the evaluation and understanding of the surface oxides layers role on the solder wettability. The present study shows that in the soldering process, even in an inert atmosphere, usually used in industry, occurs the formation of superficial oxides, over the liquid solder and/or at the pad surfaces, that strongly affects the solder paste wettability, specially with Sn and OSP (organic solderability preservative) finishing. Differences in contact angle of ≥?10° were determined between the two types of used atmospheres. The experimental surface tension and theoretical surface tension obtained, for the NiAu substrate type, present good correlation. The lower contact angle values were obtained for the NiAu and OSP finish types, independently of the atmosphere type.     

Sb对锌液与X80钢表面润湿性影响的研究

目的通过添加不同量的Sb元素降低锌液表面张力,提升X80管线钢热浸镀锌可镀性及镀层质量。方法采用改良座滴法在450℃下进行润湿实验,利用轴对称液滴分析软件(ADSA),计算不同Zn-Sb合金熔体在X80钢基板上的接触角,得到450℃时Zn-Sb合金熔体表面张力。通过能谱仪和扫描电子显微镜对镀层表面及截面的微观形貌和组织结构进行分析。结果当Sb添加量为1.0%时,450℃下Zn-Sb合金表面张力约为0.63 N/m,随Sb含量的增加,表面张力逐渐减小,当Sb含量增加到4.0%时,表面张力达到0.46 N/m,远低于纯锌液的0.79N/m。同时,Zn-Sb合金熔体与X80钢的接触角也从最初的57°逐渐减小到43°。锌合金熔体与X80钢界面处形成铁锌化合物组成的连续反应层,且在反应三相线外存在前驱膜,前驱膜的形成使随后的合金液在其上铺展,促进了润湿。结论Sb的添加能有效降低锌液表面张力,减小Zn-Sb合金熔体与X80钢间的接触角。Sb的表面张力较小,倾向于在锌合金表面富集,其作为表面活性元素降低锌液表面张力,从而提高润湿性。     

Measurement of surface crystallinity of PAA and PAANa coatings and its effect on hydrophilicity of coatings

1　INTRODUCTIONAsanimportantwater solublemacromoleculecompound,poly (acrylicacid) (PAA)anditssaltshavebeenwidelyused[1] .Utilizingitsfinefilm form ingcapacityandhydrophilicity ,Okoroaforetal[2 ] ,andPanetal[3] developedanewhydrophilicpaintforaluminiumfin[2 ,3] .Hydrophilic paintforheat ex changerofairconditioningdemandslittlesurfacecon tactangle ,sothatcontinuoushomogeneouswaterfilmcanformeasily ,andcandrainoffcondensedwa teronthesurfaceoffintimely[4 6 ] .Hydrophilicityofcoatingsisaffec…     

Bi对锌液与X80钢表面润湿性的影响

通过改良静滴法研究Zn-xBi(x=0.5,1.0,1.5,2.0)合金熔体在450℃下与不同基板的润湿行为,对润湿反应之后的表面张力进行计算,并使用扫描电镜能谱仪(SEM-EDS)分析润湿试验后的试样表面及截面的微观形貌和组织结构。结果表明,在450℃下,Zn-Bi合金表面张力随Bi含量增加呈现先减小再增大的规律。Zn-1.0Bi合金熔体与X80钢的接触角最小,表明添加1.0%Bi(质量分数)后的锌液润湿性最好。Zn-Bi合金熔体中Bi的含量对界面反应强度和界面结构产生影响,进而减小表面张力和接触角。润湿初期Bi元素的快速吸附降低锌液表面张力,使接触角减小。中期由界面反应强度控制,此时形成前驱膜且其促进锌合金熔体在钢基板的流动,从而改善润湿性。     

On the size dependence of a contact angle

A small drop on a flat solid surface is considered in this paper. In the framework of a unified approach (Gibbs dividing surface method), expressions for the interfacial tension at the liquid-vapor interface and for the contact angle were found. It is shown that introduction of the size dependence of the interfacial tension at a curved liquid-vapor interface is equivalent to using the concept of line tension on the three-phase solid-liquid-vapor boundary. It is noted that the calculations are in agreement with experimental data obtained using an atomic force microscope.     

Effect of Nd and La on surface tension and wettability of Sn-8Zn-3Bi solders

Maximum bubble pressure measurement was employed to evaluate surface tension of Sn-8Zn-3Bi- （0-0.15）Nd and Sn-8Zn-3Bi-（0 -0. 15）La solder melts. Wetting balance method was used to measure wetting force and wetting time on Cu substrate of the two group solders. The experimental results show that minute amount of Nd or La addition to Sn-8Zn-3Bi solder causes significant decrease of the surface tension of the solder melts at 200 - 240 ℃ and Nd addition is more effective on reduction of surface tension than that of La. Nd or La addition has the effect on enhancing the wetting force of the solder melts on Cu substrate, which results from the de- crease of interracial tension between the solder melt and Cu substrate. The wetting force reaches the maximum when 0.1% Nd is added to the base alloy. The contact angle between Sn-8Zn-3Bi base solders and Cu substrate decreases with the addition of Nd or La and the minimum of the contact angle is obtained from the solder with 0.1% Nd addition.     

SURFACE TENSION OF MOLTEN IF STEEL CONTAINING Ti AND ITS INTERFACIAL PROPERTIES WITH SOLID ALUMINA

Surface tension of molten IF steel containing Ti and contact angle between the liquid steel and solid alumina were measured with sessile droplet method under Ar gas atmosphere at 1500, 1575 and 1600℃. The results show that titanium decreases the surface tension of themolten IF steel and the contact angle. The interfacial tension between the molten IF steel containing Ti and solid alumina decreases with increase in titanium content. The work of adhesion between molten IF steel containing Ti and solid alumina decreases slightly at1550~C, but increases at 1600℃ with increasing titanium content. It can be deduced that fine bubbles and fine alumina inclusions are easily entrapped in solidifying interface for IF steel containing Ti.     

毛细管法测量液体表面张力的误差分析与特性研究

通过Bashforth—Adams方程获得了真实接触角,在此基础上分析了毛细管法测量液体表面张力的误差来源,解决了这一领域存在的一些争议性问题,并进一步揭示和探讨了毛细管法测量液体表面张力的特性。     

Ge–Al and Sn–Al alloys capillary properties in contact with aluminum nitride

Experimental isotherms are presented for (1) wettability of AlN ceramics by Ge–Al and Sn–Al alloys, (2) surface tension and density of Ge–Al and Sn–Al alloys in the whole concentration range. Complex consideration of capillary characteristics of the melts under study is performed taking into account data available on thermodynamic activities of the melt components. The contact angle isotherms pass the minimum point for both systems. The contact angle value drops with Al addition more sharply for the Sn–Al system than for the Ge–Al alloys. This is in qualitative agreement with the higher thermodynamic activity of the components of the Sn–Al alloys. Sn decreases Al surface tension more than Ge. The reason for this is not only lower surface tension of Sn as compared to Ge, but also the higher thermodynamic activity of Sn in the Al melt.     

TiNi及Co合金生物医用材料的腐蚀行为及血液相容性

采用线性极化技术测量了生物医用材料TiNi形状记忆合金, CoCrNiMo和CoCrNiW的腐蚀速率, 并用动态电位扫描法考察了其阳极极化行为. 结果表明, 3种合金钝化电位区宽, 维钝电流密度小, 显示出优异的耐全面腐蚀性能. 电位扫描曲线滞后环面积及腐蚀后扫描电镜观察显示, 两种钴合金具有良好的耐孔蚀性能, 而TiNi的孔蚀倾向较大, 这是因为在TiNi合金表面夹杂的Ti2Ni易受活性阴离子的浸蚀, 而钴合金中的Co, Cr, Mo和W均易在表面形成钝性氧化膜, 抑制孔蚀的发生. 接触角、动态凝血时间和溶血率的测定表明TiNi具有更优的血液相容性, 这可能与其表面的TiO2膜具有较小的表面张力有关.     

Roughness-dependent wetting and surface tension of molten lead on alumina

Surface roughness is an important factor that affects the wetting of molten metal on ceramics. The effect of surface roughness of the alumina substrate on the contact angle, contact diameter, drop height and surface tension of molten lead was investigated in the temperature range of 923–1123 K. The microstructure of the lead/substrate interface was observed by SEM. The surface free energy of alumina substrates was calculated by the geometrical average method. When the surface roughness of the substrate increased from 0.092 to 2.23 μm, the surface free energy increased gradually, ranging from 13.356 to 39.998 mJ/m². The contact diameter of lead droplets decreased from 9.111 to 7.19 mm. The lead drop height increased from 3.41 to 3.85 mm. The contact angle increased from 113.05° to 137.15°. Moreover, the surface depression of the alumina substrate was filled with lead, and no obvious change was observed. The results demonstrated that the wetting of lead drop on alumina substrates was consistent with the Wenzel state.     

On the application of modelling to study the surface and interfacial phenomena in liquid alloy–ceramic substrate systems

The wetting phenomena of molten alloy/ceramic substrate depend on the bonding characteristics of liquid alloys and ceramics as well as on the magnitude of interactive forces at the interface. According to this, the first step of this investigation is to determine the surface properties of Ag–Cu, Ag–Ti and Cu–Ti liquid alloys. The energetics of mixing in liquid alloys has been analysed through the study of surface properties (surface tension and surface composition) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the frame of statistical mechanical theory in conjunction with the quasi-lattice theory (QLT). The results obtained for these binary systems have been extended to the ternary Ag–Cu–Ti system. Combining the Young and the Dupré equations, the computed results of surface tension together with contact angle data have been used to calculate the work of adhesion and, in the case of non-reactive wetting, the interfacial tension between the solid substrate and the liquid alloys over the whole concentration range. The evaluation of the interfacial tension values is determined from calculated and measured data using solid surface tension data from literature. These results provide more information on the characteristics of metal–ceramic systems, and are therefore useful in guiding experiments, or in predicting the surface properties of metallic systems with similar characteristics as well as their wetting behaviour in contact with ceramic materials.     

Pb-Free solders: Part 1. Wettability testing of Sn−Ag−Cu alloys with Bi additions

Maximum bubble pressure, dilatometric, and meniscographic methods were used in the investigations of the surface tension, density, wetting time, wetting force, contact angle, and interfacial tension of liquid alloys of Sn−Ag−Cu eutectic composition with various additions of Bi. Density and surface tension measurements were conducted in the temperature range 250–900 °C. Surface tensions at 250 °C measured under a protective atmosphere of Ar−H₂ were combined with data from meniscographic studies done under air or with a protective flux. The meniscographic data with a nonwetted teflon substrate provided data on interfacial tension (solder-flux), surface tension in air, and meniscographic data with a Cu substrate allowed determinations of wetting time, wetting force, and calculation of contact angle. The calculated wetting angles from meniscographic studies for binary Sn−Ag eutectic and two ternary Sn−Ag−Cu alloys were verified by separate measurements by the sessile drop method under a protective atmosphere with a Cu substrate. Additions of Bi to both ternary alloys improve the wettability and move the parameters somewhat closer to those of traditional Sn−Pb solders.     

A study of the initiation of the tombstoning effect on leadless chips

The surface tension of molten solder is considered to be the source of the force causing the initiation of the tombstoning effect. The contact angle, which varies with the length of the printed circuit board solder land, has a significant effect on the value of the surface tension acting as a force pulling upward on the component. An analytical method is established for the calculation of the conditions of tombstone initiation. The formula derived from the analysis shows that initiation of tombstoning is due to the combined effects of the surface tension; the weight of the component; the dimensions of the component; the length of the solder underneath the component; and the length of the solder protruding from the end of the component. Selected components are used as examples for predicting the conditions of initiation, and these conditions are further substantiated by a series of experiments.     

减压式先导阀手柄操纵角与触头位移关系计算及压盘结构优化

提出减压式先导阀手柄操纵角与触头位移关系的精确算法,与目前用线性计算公式近似计算触头下降位移的方法进行比较,发现在小角度范围内,触头实际位移与线性计算结果基本相等,但角度变大后,两者误差越来越大。利用SolidWorks建立先导阀三维模型,模拟验证了精确算法的正确性。以提高减压式先导阀微调操控性能为目标,对先导阀压盘进行结构优化,从而补偿了手柄操纵角变大带来的误差,增大了手柄操纵角的线性使用范围。     

硅橡胶在积污过程中的润湿行为

利用静态接触角法、接触角滞后和HC喷水分级法对自然积污过程中的硅橡胶进行了表面润湿性研究,用粗糙度仪和扫描电镜对样片进行表征分析,研究发现:随着硅橡胶不断的积污,表面粗糙度越大,静态接触角随之也增大,接触角滞后变小,滞后由小到大的顺序是:S3(中污)S4(板结)S1(清洁)S2(轻污)。另外,积污后的硅橡胶表面的润湿特点跟润湿方式有关,如当静态水珠润湿其表面时,表现很好的憎水性,接触角可高达130°以上,当以强烈水流冲击其表面润湿时,表现憎水性较差,憎水分级多数为HC5-HC6。     

Zn元素含量对AgCuZn钎料在TiC金属陶瓷表面润湿性的影响

在AgCu共晶钎料中添加不同量的Zn元素熔炼成AgCuZn钎料,并在陶瓷表面进行润湿试验.结果表明,当Zn元素含量为25%(质量分数)时,钎料在陶瓷表面润湿角最小,为23.5°;从近钎料外表面到钎料/陶瓷界面,组织依次为(Cu,Ni)+Ag(s.s)+Cu(s.s)/Ag(s.s)+Cu(s.s)/(Cu,Ni)/Ag(s.s)+Cu(s.s)+TiC金属陶瓷/TiC金属陶瓷.随着钎料中Zn元素含量增加,钎料/TiC金属陶瓷界面处(Cu,Ni)固溶体形态由块状弥散分布变为层状分布;Zn元素在真空中挥发能促进界面元素的溶解和扩散,从而使固液界面张力减小、钎料表面张力增大,最终导致润湿角随着钎料中Zn元素含量增加而出现最小值.     

棉纤维束与金属摩擦行为研究

目的 基于接触力学模型对棉纤维与不锈钢303摩擦辊摩擦行为进行研究。方法 采用自制绞盘式摩擦试验装置,从预加张力、粗糙度、摩擦速率和棉纤维束包角4个方面探究了棉纤维束与金属摩擦辊表面的摩擦行为,并建立棉纤维与粗糙峰接触模型对试验结果加以验证。结果 预加张力与摩擦力呈正相关,与摩擦因数呈负相关。摩擦力与摩擦因数随所选粗糙度的增大而减小。摩擦速率只对摩擦系统达到稳定的周期数有影响,对摩擦行为的影响较小,摩擦速率较小时,系统达到稳定所需周期更长。包络角度增大,摩擦力增大,摩擦因数变化较小,包络角度越小震荡越明显。结论 与摩擦速率及包络角度相比,粗糙度和预加张力对棉纤维束与金属表面摩擦磨损行为影响更大。     

激光织构化不同材料表面对润湿性能的影响

采用激光微织构加工技术分别在SAF2507双相不锈钢和碳纤维增强聚醚醚酮(CF/PEEK)表面制备不同形状、面积占有率的微织构凹坑，通过润湿性试验分析时间、液滴体积、微织构形状与面积占有率、液滴种类对润湿性的影响。结果表明：液滴润湿材料表面过程中，固液接触角先随时间迅速减小，后保持在一个较为稳定的值；使用体积较大的液滴测量接触角时，液滴铺展的速度减缓，接触角的测量值变小；CF/PEEK表面的接触角随微织构面积占有率的增大而减小，SAF2507表面的接触角随微织构面积占有率的增大而增大；微织构面积占有率相同的表面，方柱形微织构表面的接触角小于圆柱形微织构表面，润湿效果更好；天然海水在光滑和织构表面的接触角均小于蒸馏水。