The authors would like to thank to Heraeus Precious Metals GmbH &amp; Co. KG for their support and supply of commercial silver pastes, especially M. K&#246;nig for fruitful discussions. Special thanks go to M. Schmalz for experimental support. C. Y&#252;ce gratefully acknowledges financial support by the 100 prozent erneuerbar stiftung. Finally, we acknowledge financial support from the Federal Ministry for Economic Affairs and Energy (Grant no. 0325775G).

注意:使用前请咨询所有相关材料安全数据表（MSDS）。几个用于银膏制剂中的组分是剧毒的，致癌的和水危害的物质。用银浆处理时，请使用所有适当安全的做法（个人防护装备 - 安全防护眼镜，手套，实验室外套，全长长裤，不露脚趾的鞋子）。还与流变仪要求工作认真细致的工作。从在几何移动到测量位置被截留保护手。 1.旋转剪切测量 - 测量报告<ol><li>表观粘度测定 - 剪切速率控制测量<ol><li>进行使用流变仪阿具有平行板几何形状（板粗糙度R Q = 2 - 4微米，板直径d = 25mm）的旋转剪切实验。所需的糊体积为0.49毫升。 <ol><li>调整测量粘度确定的设置。开展逐步受控的剪切速率模式测量<img alt="方程" src="/files/ftp_upload/55377/55377eq1.jpg" /> = 0.01 -1 - 1000秒-1在40步。测量时间是1200秒。 </li><li>放置设备，用于记录在位置测量间隙:相机三脚架与连接的内窥镜摄像机，LED聚光灯，并且外部计算机以保存记录。调整曝光场的内窥镜摄像机的设置， 例如对比度和亮度。 </li><li>只是填满流变仪间隙之前，所以浆料均匀地混合在贮存混合样本。 </li><li>填补了与混合银浆样品的流变仪的差距。 注意:用于h = 结束 1毫米的测量间隙的高度，首先去一个间隙位置h 1 = 1.05毫米从流变仪几何形状的边缘除去过量的样品。 ℃之后性学习的了过量的样品，改变从h 1至h 端实际间隙高度位置。 </li><li>为了显现在测量间隙的膏流中，标记与煤烟颗粒的膏剂中的垂直线。 </li><li>开始测量之前，等待约5分钟，直到在间隙法向力已经衰退。 </li><li>开始测量。开始在同一时间测量装置和录像遵循的差距粘贴和正确地测量相关设置，流变结果，和录像。 </li><li>重复测量步骤1.1.1.3 - 1.1.1.7至少三次。 </li><li>画出表观粘度η 应用与表观剪切速率<img alt="方程" src="/files/ftp_upload/55377/55377eq1.jpg" /> 应用对数。评估录像检查支配墙滑，贴变形的部分，和样品溢出的部分的部分。的参数设置，其具有均匀的sh耳外形形成能够容易地检测基于视频记录（ 图1）。 注意:在板的边缘处的剪切应力从由流变仪和在所述板的在稳定状态下边缘处的表观剪切速率施加的记录的扭矩来计算。表观剪切速率称为板的角速度，并在最大半径板的间隙高度h。 </li></ol></li></ol></li><li>屈服应力的测定 - 用不同的板粗糙度和叶片几何剪应力受控的测量的比较<ol><li>屈服应力测量与R Q = 1.15微米的一个板粗糙度。 <ol><li>对于其中R Q测量= 1.15微米，与D = 20mm的板直径使用流变仪B中。所需的糊体积为0.31毫升。 </li><li>调整屈服应力测量的测量设置。开展逐步受控的剪切应力米测量颂。变化1帕之间，以3000帕35个步骤与1050秒的总的测量时间上的剪切应力。 </li><li>组装与连接的内窥镜摄像头，LED射灯，外部计算机与软件相机三脚架来保存录像。调整内窥镜摄像机的设置， 例如曝光场的对比度和亮度。 </li><li>填充银膏中的测量间隙之前，在其贮存混合样品以确保其均匀地混合。使用高速混合机（30秒以1,000rpm）。混合后，填补了糊的差距。 </li><li>采取混合糊的量小，其应用到平行板流变仪的底板，并把上板到测量位置。 注:对于具有间隙高度h 端 = 1毫米的测量，首先转到间隙位置h 1 = 1.05毫米，从流变仪几何形状的边缘除去过量的样品。清理多余的SAM后PLE，更改从h 1至h 端实际间隙高度位置。 </li><li>标志着在垂直线上的烟灰粒子的测量间隙的糊状物。这使得膏变形和流动在该间隙中以及壁滑动的可视化。 </li><li>开始测量之前，等待约5分钟，直到在上板的法向力也消失了。 </li><li>现在开始测量。开始在同一时间测量装置和录像遵循的差距粘贴和正确的测量设置属性来录像。 </li><li>继续测量，直到糊洒出的差距。 </li><li>重复总共测量三次。对于每次测量，清洗用乙醇，测量间隙并重复步骤1.2.1.4 - 1.2.1.9。 </li><li>当测量完成时，绘制变形γ对剪切应力τ对数，并使用唐恩确定介质的屈服应力吨交点方法33。 </li></ol></li><li> 4微米-在R Q = 2的板粗糙度屈服应力测量值。 <ol><li>对于具有R Q = 2的测量- 4微米，使用流变仪A和的D = 25mm的板直径。所需的糊体积为0.49毫升。 </li><li>重复步骤1.2.1.2 - 1.2.1.11用于与板粗糙度R Q = 2的屈服应力测量值- 4微米。 </li></ol></li><li>在R Q = 9微米的板粗糙度屈服应力测量值。 <ol><li>对于具有R Q = 9微米，其中d = 20mm，并且需要膏体积0.31毫升的板直径使用流变仪乙测量。使用双面粘合带砂纸件附着到匹配它们的直径的板。 </li><li>重复步骤1.2.1.2 - 1.2.1.11用于与板粗糙度R Q = 9微米的屈服应力测量值。 </li></ol></li><li>产量stress测量与叶片的几何形状。 <ol><li>用于与所述叶片几何屈服应力测量值，使用流变仪C. </li><li>调整屈服应力测量的测量设置。开展像平行板测量逐步受控的剪切应力模式的测量1.2.1，1.2.2或1.2.3。的参数值τ= 1 - 3000帕35个步骤和1050秒的总的测量时间。 </li><li>与样品填充所述圆柱形量杯之前，在其贮存混合样品，以保证样品均匀地混合。混合填充用10mL银膏圆柱形量杯后。 </li><li>移动叶片几何到测量位置，等待5分钟。 </li><li>现在开始测量。 </li><li>对于可靠的结果，重复测量至少三次。 </li><li>当测量完成时，绘制变形γ对剪切应力τ对数，并使用确定的屈服应力切线交点的方法如上所述。 </li></ol></li></ol></li><li>墙滑观察<ol><li>使用流变仪乙有板直径d = 20mm的板粗糙度R Q = 1.15微米执行壁滑移观测。 <ol><li>调整为壁滑移判定测量设置。进行在受控的剪切应力模式测量为400 Pa和1300帕和300的总的测量时间之间选择的剪切应力。 </li><li>放置设备的位置在测量间隙的录音:相机三脚架与连接的内窥镜摄像机，LED聚光灯和外部计算机以保存记录。调整曝光场的内窥镜摄像机的设置， 例如对比度和亮度。 </li><li>填充银膏中的测量间隙之前，在其贮存混合样品以确保其均匀地混合。 </li><li>填充有混合银膏样品流变仪间隙。 </li><li>标记在用于流动行为观察的垂直线与煤烟颗粒的测量间隙的糊状物。 </li><li>开始测量之前等待约5分钟，直到在间隙法向力已经衰退。 </li><li>开始测量。开始在同一时间测量装置和录像遵循的差距粘贴和正确地测量相关设置，流变结果和录像。 </li><li>重复步骤1.3.1.3 - 1.3.1.7三次，每次选择的剪切应力。 </li><li>积壁滑移速度v 滑移对剪切应力τ，以显示壁滑移性能（ 图9）。 </li></ol></li></ol></li><li>旋转剪切测量样品中调查漏油事件<ol><li>执行与流变仪A（板直径d = 25毫米，所需的糊体积0.49毫升）样品溢出调查。 <ol><li>为了确定样品溢出的发生的上间隙高度h依赖在不同的差距高度1.1.1.8 - 运行步骤1.1.1.1。 注:对于测量 H的终端 =0.2毫米先去间隙位置h 1 = 0.21毫米，除去多余的样品 从流变仪几何形状的边缘 H的终端 =0.5毫米→H 1 =0.51毫米 H的终端 =1.0毫米→H 1 =1.05毫米 H的终端 =1.5毫米→H 1 =1.55毫米 H的终端 =2.0毫米→H 1 =2.05毫米</li><li>本发明的结果作为表观粘度η 应用与表观剪切速率的曲线图<img alt="方程" src="/files/ftp_upload/55377/55377eq1.jpg" /> 应用程式不同的间隙高度（ 图10）。确定在该曲线的扭结和相应的临界转速n 爆击和绘制这与该间隙的高度h（ 图11）。 </li></ol></li></ol></li><li>流变表征吨高剪切速率与毛细管流变仪进行<ol><li>执行使用具有圆形横截面的喷嘴毛细管流变仪测量。使用具有直径d = 0.5毫米，长度L =此处40mm的喷嘴。进料储存器的直径为d的进料 = 20毫米。 <ol><li>调节测量设置（之间0.001毫米小号活塞速度-1和20mm -1）。开展逐步受控的剪切速率测量时，5秒为每个测量点。 </li><li>混合样品，以保证浆料均匀地混合，并填充进储存器与78.5毫升银膏。 </li><li>带来测量位置的活塞，然后开始测量。 </li><li>从样品室和毛细管出口之间的压力差来计算剪切应力。确定使用500巴的压力换能器本压降。记录至少5为每个选定的活塞速度的压力值。 </li><li>继续测量，直到饲料资源ervoir是空的。 </li><li>重复测量（步骤1.5.1.2 - 1.5.1.5）的三倍。 </li><li>计算从使用进料储存器的活塞速度和直径的体积流率的表观剪切速率和执行魏森伯格-Rabinowitsch校正。计算壁剪切应力τW从测量的压力差34。表观粘度然后作为应用 η=τW /给出<img alt="方程" src="/files/ftp_upload/55377/55377eq1.jpg" /> 应用程序 。最后，绘制表观粘度对表观剪切速率在高剪切速率（ 图12），以完成流变学表征。 </li></ol></li></ol></li></ol> 2.振荡剪切测量<ol><li>振幅扫描<ol><li>用流变仪进行振幅扫描测量的使用的D = 25mm的板直径和粗糙度R Q = 2 - 4微米。该requirED膏体积为0.49毫升。 <ol><li>调整振幅扫描测量的测量设置。执行在受控变形幅度测量<img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> = 0.01 - 100％和f = 1赫兹的在35层的步骤的恒定的频率。 </li><li>重复步骤1.2.1.3 - 1.2.1.8完成振幅扫三次。清洁每次测量前用乙醇测量间隙。 </li><li>绘制模量G"和G‘’与变形振幅<img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" />对数（ 图13）。变形幅度范围，其中，G"&gt; G‘’和模量都运行变形振幅的独立平行<img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> ，是线性粘弹性体制（LVE）。对于结构恢复测试选择一个变形振幅从该区域为步骤I和工序III<html> 。对于随后的三级结构恢复试验的步骤II中选择变形振幅高于10％ <img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> 交叉在其中G" = G‘’，以确保结构击穿的结构恢复测试之间。 </li></ol></li></ol></li><li>三级结构恢复测试<ol><li>执行与流变仪的结构恢复测试使用直径为d = 25毫米，粗糙度R Q = 2的板配备- 4微米。使用在幅度扫描试验（2.1）确定的设置。所需的糊体积为0.49毫升。 <ol><li>执行与在恒定频率（f = 1赫兹）不同的振荡幅度的三阶段振荡测试。 注意: 阶段I:在LVE内小振荡幅度被施加一段300秒，以获得初始状态的剪切模量。对于糊B文件/ ftp_upload / 55377 / 55377eq2.jpg" /&gt; I = 0.025％。 阶段II:大应变振幅（ <img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> II = 80％）在步骤2.1确定在振荡剪切模式时间依赖性调查施加吨II = 50秒，150秒或600秒。对于变形的依赖性的研究之间的应变振幅<img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> II = 0.025％和<img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> II = 100％施加每个恒定时间（t II = 150秒）。 阶段III:相同的小振幅等在施加I期为1200 s到跟随在一段较长的时间的恢复。 </li><li>重复步骤1.2.1.3 - 1.2.1.8完成三个阶段的振荡测试三次。清洁测量gFAP与每个测量之前乙醇。 </li><li>积在半对数图的模量G"和G‘’相对于时间（参见图14和图 15 的（a））。 </li></ol></li></ol></li></ol> 3.拉伸性能的测定 - 一个快断模拟<ol><li>拉伸行为的测量与毛细管破裂拉伸流变仪<ol><li>执行与毛细管破裂拉伸流变仪拉伸实验。使用两个圆筒形的活塞直径为d = 6毫米。在从最初的间隙高度h =1毫米直到长丝断裂变化速度拉伸糊剂。 注:请注意，这不是由表面张力控制的典型长丝细化实验。该试验也可与附接有乳剂侧在上活塞和底部的晶片衬底上的筛网进行。这娃单晶和多的金属化时产生ÿ印刷工艺在工业上预处理的硅晶片被模仿。 <ol><li>调整拉伸实验测量设置。改变拉伸速度（ 例如 :7.5毫米-1，11毫米-1和110毫米-1），以查看在灯丝变形和破裂行为的变化。 </li><li>开启高速摄像机来记录丝形状的变化。设置帧速率，以最小250个FPS和打开背光跟踪灯丝变形。也调整高速相机设置，特别是图像的清晰度，对比度和曝光场的亮度。 </li><li>填充银膏中的测量间隙之前，在其贮存混合样品，以保证浆料均匀地混合。混合后，填充用浆糊测量缺口。 </li><li>采取混合膏少量（28.3μL）应用它在底活塞。带上UPPER活塞与所述测量位置（测量间隙高度h = 1毫米），清理从几何的边缘多余的样本。 </li><li>启动该测量装置和灯丝变形的同时录音。 </li><li>重复测量三次。对于每次测量，清洗用乙醇，测量间隙并重复步骤3.1.1.3 - 3.1.1.5。 </li><li>选择第一画面表示灯丝断裂来评价活塞位置x 断裂在其中灯丝断裂。计算临界拉伸比率（x BR - X 0）/ X 0 =ΔXBR / X 0。确定该数量对于不同的拉伸速度（ 图16）。 </li></ol></li></ol></li><li>拉伸力测量与拉伸试验机<ol><li>对于拉伸试验机实验用的活塞直径为d = 5毫米。记录所得10在拉伸过程中西莱力。 <ol><li>调整拉伸实验测量设置。改变拉伸速度， 例如 V =10毫米-1为20mm -1为30mm -1，和40mm -1和测量与50N的测力传感器的拉伸力的变化。设置初始间隙高度h为h = 1毫米，端部位置为h 端 = 12毫米。 </li><li>填充银膏中的测量间隙之前，在其贮存混合样品，以保证浆料均匀地混合。 </li><li>应用粘贴到拉伸试验机的底板。使上板与所述测量位置和从几何的边缘清理过量的样品。 </li><li>启动测量装置和长丝伸长同时录音。 </li><li>重复测量三次。对于每次测量清洁测量间隙并重复步骤3.2.1.2 - 3.2.1.4。 </li><li>从F对[6; 如图17×数据的最大的力F 最大延伸期间检测和断裂ΔXBR / X 0的拉伸比是（a）得到。情节ΔXBR / X 0对比的不同的拉伸速度（ 图17的（a））。积F 最大与拉伸速度（ 图17的（b））。 </li></ol></li></ol></li></ol>

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The authors have nothing to disclose.

高度浓缩的悬浮液或浆料的全面流变学表征是强制性的有针对性的产品开发会议处理和这种复杂流体的应用过程中的歧管的要求。此调查包括屈服应力，粘度，壁滑移速度，结构恢复的大变形和断裂伸长率以及灯丝期间拉伸力拉伸后的判定。所有的摘要应用的方法，所获得的信息，和粘贴特性总结在表1中 。 视频记录的高填充混悬剂表示壁滑移，剪切带和样品溢出在平行板流变测定法旋转流变量的可靠确定的重要性被证明。录像使真变形轮廓的在使用合适的标记是样品轮缘测定和流场。这是necessARY分析的流变实验结果之前研究这个变形行为。因此测量的参数设置和板的粗糙度值可以被识别为其中粘度测量是可能的。该糊屈服应力可以使用具有适当的粗糙度的叶片几何或板 - 板几何形状来确定任一。 粘度测定是使用可能的板 - 板几何形状仅与取决于样品组合物仔细选择板粗糙度。较高的粗糙度并不必然导致下壁滑。其中粘度测定是可以做到的剪切速率或剪切应力范围由屈服应力和样品溢出的发生的限制。 此外，滑移速度可以直接测量，并在其中活塞流，剪切带或样品溢出发生测定条件可以清楚地被识别。对于壁滑动测量光滑表面被用作上面的剪切PLATE和一个粗糙的底板，以允许仅在上板滑动。此滑动速度可以直接从上板的角速度来计算。对于这两种糊剂打滑发生在应力水平远低于表观屈服应力。类似的观察已经报道了的玻璃珠25，粘土悬浮液27，软微凝胶糊剂以及用于乳液28，29，30的悬浮液。这里v 滑移与τ 应用的线性增加被发现。这与咸海等人的观察结果一致。 25谁也使用流场的可视化在所研究的玻璃珠悬浮液的边缘，确定V 滑移 。 Seth 等人。已经表明，与外加应力滑动速度的缩放由软partic之间的相互作用来控制LES他们在学习和墙壁使用。对于其中有颗粒与壁的没有具体的粘附的情况下，他们也发现v 滑移和应力，但二次缩放被发现对于弱粘附于壁28，29，30中的粒子之间的线性关系。软粒子糊剂研究还在屈服应力揭示的特性滑动速度V *和一个弹模型被呈现29允许从可被独立地确定物理流体和粒子参数计算V *:V *〜γY 2（G 0 R /ηS）（G P / G 0）1/3。这种特性滑移速度取决于糊剂屈服应变γy和弹性模量G 0，溶剂的粘度ηS，以及particlÈ半径R和模量G P上 。值从这个简单的估计得到的（V A * = 375微米-1和V B * = 118微米-1）吻合很好与实验结果（ 图9）不仅相对于大小，而且顺序关于糊A和B之间的区别样品溢出在每个糊的临界转速特性这里观察。溢出不会在纯粹的车辆发生。这种现象限制了浆料的流变学特性，也可能是相关的某些处理或涂层的操作，但它的物理根源仍未解决。 录像进一步表明壁滑动，活塞流和样品溢出可以在振荡剪切试验中排除。因此，在剪切模量的降低和增加期间用SmaI三级振荡剪切测试中观察到在阶段I和III升振幅以及大变形振幅<img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> &gt; <img alt="方程" src="/files/ftp_upload/55377/55377eq2.jpg" /> C可直接归因于结构性打破和恢复。它可以表明，在对应于G的振幅扫描测试交叉"和G‘’变形达到期间在阶段II随着变形振幅振荡剪切增加直到饱和不可逆的结构变化的程度，但不可逆的损伤是独立的高振幅剪切的持续时间在阶段II。因为等待超过10 4秒次后在模量，因此样本结构由于在阶段II大的剪切变形的变化称为不可逆这里，储能模量远远大于它的初始值的情况下（未示出数据）。在图15所示的数据被限制到等待为清楚起见，1500个s&#39;的次数。然而，应该指出的是，印刷工艺的时间尺度是秒或甚至低于量级。这不是在这个研究中使用的传统的旋转流变仪设置访问。 在此研究中使用的间隙的高度也比在现代印刷电子的丝网印刷典型网眼大得多。使用板 - 板几何结构流变学测量不能在如此小的间隙的开口来完成，由于为典型地在流变学测量中使用大板机械调节的限制。此外，大的间隙分离在这里已经选择了在轮辋缓解样品变形的可视化。 使用毛细管破裂拉伸流变仪和拉伸试验机拉伸长丝的测试可以被用于表征在拉伸流动高度填充的糊的变形和破裂行为。在断裂和第m伸长伸长期间aximum力是由这些试验所获得的参数和丝网印刷过程中可能与刮板卡扣关闭。 最后，在以上在本研究调查的两个商业银浆描述的所有实验中观察到显著的差异。对于自己的表现流变糊化特性的相关性的进一步讨论将在基于数据的各种各样不同的糊和车辆的后续文件来解决。

硅太阳能电池的前侧金属化是使用传统的丝网印刷通常实现。此外模板印刷，喷墨印刷和柔版印刷1，丝网印刷已自20世纪70年代的许多印刷应用2中。它是一种通用的技术和在太阳能电池生产，它确保以低打印成本简单和快速的金属化。然而，丝网印刷浆料的流动特性，必须小心地调整以确保无干扰，无缺陷处理。这是在太阳能电池的金属化特别具有挑战性的，因为窄的均匀的线图案必须被实现。此外，膏配方必须仔细调整，以避免高密度的银粒子，相分离和颗粒聚集的沉降。 用于太阳能电池的正面金属化的高度浓缩的导电丝网印刷膏成为内地ÿ由三个部分3，4，5，6的:导电材料，一般微米尺寸的银颗粒提供良好的导电性7,8;连续相，即所谓的车辆，有机粘合剂，溶剂和添加剂促进粒子的润湿性，成膜性和粘附性，其中还包括添加剂，以调节流动行为，特别是使糊剂中的基板的混合物通过狭窄的筛网容易;和无机粘合剂（玻璃粉末）作为粘合促进剂和在较低温度下激活烧结过程。 印刷细纹具有高纵横比要求表现出高的屈服应力和显着的剪切变稀行为9银膏。高屈服应力，保证良好的十八当浆料流经窄网孔，其中，所述糊状物被暴露于估计为超过10 3秒的高剪切速率Ë精度和高的纵横比，而强烈剪切稀化和相应低的粘度在高剪切速率是必要-1 10。 在印刷过程中，膏状物暴露于非常不同的变形率和应力。首先，贴贴在屏幕上;然后刮板行为和浆料穿过筛孔到衬底上。在硅晶片上，结构和粘度的糊状物施加后必须迅速恢复到禁止糊在基板上扩散。这将降低太阳能电池的性能由于较高的阴影损失10，11，12，13，14，15。中断，即所谓的meshmarks，在印刷指线可以在取决于膏的流变网线的交叉点发生。用于拉平meshmarks的时间应该是，只要有必要，但也足够短，以保持手指线蔓延尽可能低16。 流经网眼到衬底上具有所需的糊刮板压力被仔细调整，以必要的，以提供良好的形状精度3，6，9，17，18中的高的屈服应力。粒子密集，强烈的相互作用，形成复杂的结构。因此，除了屈服应力，剪切稀化和触变，可能发生在这样的悬浮液19的各种其它复杂的流动现象等剪切带或雪崩，20 &lt;/ SUP&gt;，21。壁面滑移也是至关重要的浓度的悬浮液22，23，24，25。薄层的较低粘度的液体， 即耗尽层或不含颗粒的毗邻壁25，26，27，28，29，30，31形成，并且可以通过窄的间隙或通道控制流动。 因此，丝网印花糊料的综合流变特性是为了改善加工性能和产品功能是必不可少的。在这项研究中，两个商业银浆的特点。这些浆料表现出显着不同的打印性能。流变字符这种材料的acterization是非常苛刻的。即使使用旋转流变仪的稳态剪切粘度的简单判定是一个重大的挑战，由于壁滑动，活塞流，剪切带和糊溢出。因此，以前的研究集中在振荡剪切测量10，17，21或低浓银膏的特性，所谓的油墨3，6，15，为此，上述现象不太可能发生。 浓银浆料的流动行为的一个强大的和有意义的表征协议可以与录像的帮助下定义。与平行板夹具样品的旋转剪切流变仪用于该研究，清楚地表明，活塞式流动，壁滑移和剪切带取决于板粗糙岬以非平凡的方式。 在以前的工作中，在浓缩悬浮液的稳定的扭转流动壁滑动的时间依赖性发展检验了不同的板粗糙度。在聚合物粘合剂溶液中的固体玻璃球的高度浓缩的悬浮液的流量可视化和增加的板或内筒的粗糙度防止壁滑移。然而，增加板粗糙度导致样品22，25的断裂。断裂发生在较小的表观剪切速率时的壁的粗糙度增加。粗糙化表面的凹凸的尖端可能会在剪切应力τ比屈服应力τý25在较小的板面作为应力集中点作用，引发断裂。 壁面滑移被认为是高度浓缩浆的丝网印刷性能非常重要。过去<html> e到网格更容易在较高的壁滑动滑轨和其在基板上沉积物显著32增加。随着录像的帮助下，壁面滑移，可直接用于不同的实验观察到的协议。滑移速度可以直接从使用平滑板具有低粗糙度的旋转板的角速度来确定。但在银膏的流动行为确定是固有的限制。所述悬浮液是不透明的，所以光流场的观察只能在样品边缘完成。以前的研究曾试图同时确定样品中壁面滑移和变形。他们观察到的屈服应力以下滑移，发现滑动速度对剪切应力的二次依赖性。透明的粘土悬浮液的流动行为是由Pignon酒店27注入到块体材料的染料颜料线的变形以下研究。 Persello 等。外部参照"&gt; 26已经调查浓缩的含水二氧化硅悬浮液。他们发现，增加板粗糙度抑制壁滑移不会导致均匀的样品变形而引起散装断裂。在软微粒凝胶颗粒并浓缩乳剂的糊剂滑和样品变形已被广泛在一系列论文中28，29，30，31中 。使用荧光示踪粒子，以确定在一个锥板几何这些透明样品内的流场的讨论。他们发现的特性滑动速度V *在相应的屈服应力材料和用于与下面τý剪切应力τ滑动速度的增加幂定律。一个的指数被发现的非粘附颗粒和两个在颗粒和壁之间的弱的吸引力的情况下。 在这项研究中提出了她Ë变形的发展和控制应力和受控剪切速率的条件下流动进行监控。与在参考25报告的结果，增加了板的粗糙度不导致断裂的两个研究糊剂。此外，壁滑移和塞流不能仅仅通过板粗糙度增加抑制。这些现象似乎是由颗粒尺寸和板粗糙度的比例来控制。在特征转速样品溢出集推测是通过作用于和摩擦在流变仪板离心力之间的平衡来确定。然而，在其中所述的粘度确定是可能的剪切速率范围可被确定，并且同时壁滑移可以量化。此外，毛细管流变仪被用来确定在相关的印刷过程中较高的剪切速率粘度。 尽管与稳态剪切流变测定，定义良好的振荡剪切变形c中的困难一个能够容易地实现。三阶段振荡测试（恒定频率，不同的振荡振幅）模拟丝网印刷工艺10，并允许研究浆料的结构恢复: 在第一个"预打印"步骤中，一个小的变形应用于静止确定弹性和粘性特性。第二"打印"步骤模拟刮刀涂布和通过施加足够高的变形振幅打破糊结构经过筛网的糊状物。在最后的"后打印"步骤中，一个小的形变被施加到检测该膏的结构恢复。初始模量值应迅速达到以免糊蔓延，但不能太快，以免meshmarks。这里介绍的调查证实，如以前周21日报道的结构性复苏是不完整的。周能表明结构变化引起通过使用悬浮在乙基纤维素溶液中的银颗粒解耦填料基质的填料簇的破裂。视频记录在该研究表明，所观察到的不可逆的结构变化是不相关的壁滑动，剪切带，活塞流或样品溢出的发生的伪影。另外，可以发现，结构破坏的程度强烈地依赖于在第二阶段所施加的变形幅度，但几乎没有取决于所施加的应变的时间间隔。这方面并没有在周的实验察觉。关于结构击穿和恢复的糊组合物的影响将在随后的纸进行讨论。 最后，模拟屏卡断期间的粘贴行为一个方法。毛细管破裂拉伸流变仪和市售拉伸试验机被用于确定拉伸比在该糊剂打破和最大轴向力拉伸作为功能期间的伸长速度。 视频记录已经被证明是用于查找必要使用平行板流变测定法旋转银膏的有意义的流变学表征合适的测量协议不可缺少的。视频数据启用剪切速率，并且其中物理地定义良好的屈服应力和粘度值可确定剪切应力制度的测定。板粗糙度和板分离参数的适当选择还基于这些视频记录。壁滑动，纯塞流，剪切带或样品溢出发生针对实验设置可以被明确地识别。这里所研究的糊剂被用于太阳能电池的前侧金属化。然而，仔细视频支持，流变学特性也是其他各种浓度的悬浮液，包括高密度，微米大小的颗粒很重要的。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>endoscopy</td>
			<td>Visitool</td>
			<td>TVS80.280.BF6.AD10.2</td>
			<td>full name: TV-Endoskop, C-Mount, Variookular 2X, &#216; 8mm x ca. 280mm, 0&#176;, BF:6mm, AD 10mm</td>
		</tr>
		<tr>
			<td>commercial silver paste&#160;</td>
			<td>Heraeus Deutschland GmbH &#38; Co. KG 
			Global Business Unit Heraeus Photovoltaics</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>rheometer A</td>
			<td>Anton Paar</td>
			<td>Physica MCR 501</td>
			<td>Rq = 2 - 4 &#181;m</td>
		</tr>
		<tr>
			<td>rheometer B</td>
			<td>Thermo Scientific</td>
			<td>Haake Mars II</td>
			<td>Rq = 1.15 &#181;m 
			Rq = 9 &#181;m</td>
		</tr>
		<tr>
			<td>rheometer C</td>
			<td>Thermo Scientific (formerly Haake GmbH)</td>
			<td>Rheostress 150</td>
			<td>vane geometry</td>
		</tr>
		<tr>
			<td>sandpaper</td>
			<td>Jean Wirtz D&#252;sseldorf Metallographie</td>
			<td>P320 C</td>
			<td>Rq = 9 &#181;m 
			grain size = 46.2 &#177; 1.5</td>
		</tr>
		<tr>
			<td>recording software</td>
			<td>Debut Video Capture</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>LED Spotlight</td>
			<td>Kaleep&#160;</td>
			<td>48W Led Work Lights 
			Offroads Lights 
			Lamp Spotlight Floodlight&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>capillary breakup elongational rheometer</td>
			<td>Thermo Scientific (Haake)</td>
			<td>HAAKE CaBER1</td>
			<td></td>
		</tr>
		<tr>
			<td>tensile tester</td>
			<td>Stable Micro Systems, Godalming, UK</td>
			<td>TA.XT plus 
			Texture Analyzer&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>50 N load cell</td>
			<td>Stable Micro Systems, Godalming, UK</td>
			<td>Serialnumber: 10256249</td>
			<td></td>
		</tr>
		<tr>
			<td>a modified capillary rheometer</td>
			<td>G&#246;ttfert Rheograph 2000 (G&#246;ttfert Werkstoff-Pr&#252;fmaschinen GmbH, Buchen Germany)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>500 bar pressure transducer</td>
			<td>Gefran, Selingenstadt, Germany</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

challenges in rheological characterization of highly concentrated suspensions &#8212; a case study for screen-printing silver pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

Watch this Scientific Journal Video about Challenges in Rheological Characterization of Highly Concentrated Suspensions Ã¢â‚¬â€ A Case Study for Screen-printing Silver Pastes at JoVE.com

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

挑战流变特性高度集中悬架 - 为例进行丝网印刷银浆

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

challenges-rheological-characterization-highly-concentrated

Nanyang Technological University

Research

JoVE Journal

Engineering

19.8K 次观看.  Karlsruhe Institute of Technology. A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems. 

视频: Challenges in Rheological Characterization of Highly Concentrated Suspensions — A Case Study for Screen-printing Silver Pastes

A Method to Fabricate Disconnected Silver Nanostructures in 3D

The standard nanofabrication toolkit includes techniques primarily aimed at creating 2D patterns in dielectric media. Creating metal patterns on a submicron scale requires a combination of nanofabrication tools and several material processing steps. For example, steps to create planar metal structures using ultraviolet photolithography and electron-beam lithography can include sample exposure, sample development, metal deposition, and metal liftoff. To create 3D metal structures, the sequence is repeated multiple times. The complexity and difficulty of stacking and aligning multiple layers limits practical implementations of 3D metal structuring using standard nanofabrication tools. Femtosecond-laser direct-writing has emerged as a pre-eminent technique for 3D nanofabrication.1,2 Femtosecond lasers are frequently used to create 3D patterns in polymers and glasses.3-7 However, 3D metal direct-writing remains a challenge. Here, we describe a method to fabricate silver nanostructures embedded inside a polymer matrix using a femtosecond laser centered at 800 nm. The method enables the fabrication of patterns not feasible using other techniques, such as 3D arrays of disconnected silver voxels.8 Disconnected 3D metal patterns are useful for metamaterials where unit cells are not in contact with each other,9 such as coupled metal dot10,11or coupled metal rod12,13 resonators. Potential applications include negative index metamaterials, invisibility cloaks, and perfect lenses.
In femtosecond-laser direct-writing, the laser wavelength is chosen such that photons are not linearly absorbed in the target medium. When the laser pulse duration is compressed to the femtosecond time scale and the radiation is tightly focused inside the target, the extremely high intensity induces nonlinear absorption. Multiple photons are absorbed simultaneously to cause electronic transitions that lead to material modification within the focused region. Using this approach, one can form structures in the bulk of a material rather than on its surface.
Most work on 3D direct metal writing has focused on creating self-supported metal structures.14-16 The method described here yields sub-micrometer silver structures that do not need to be self-supported because they are embedded inside a matrix. A doped polymer matrix is prepared using a mixture of silver nitrate (AgNO3), polyvinylpyrrolidone (PVP) and water (H2O). Samples are then patterned by irradiation with an 11-MHz femtosecond laser producing 50-fs pulses. During irradiation, photoreduction of silver ions is induced through nonlinear absorption, creating an aggregate of silver nanoparticles in the focal region. Using this approach we create silver patterns embedded in a doped PVP matrix. Adding 3D translation of the sample extends the patterning to three dimensions.

Femtosecond-laser direct-writing is frequently used to create three-dimensional (3D) patterns in polymers and glasses. However, patterning metals in 3D remains a challenge. We describe a method for fabricating silver nanostructures embedded inside a polymer matrix using a femtosecond laser centered at 800 nm.

一个断开连接的银纳米结构的方法来制作的3D

The standard nanofabrication toolkit includes  techniques primarily aimed at creating 2D patterns in dielectric media. Creating  metal patterns on a ...

科研

工程学

Evaluating Plasmonic Transport in Current-carrying Silver Nanowires

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information support1,2,3. In this context, metal nanowires are especially desirable for realizing dense routing networks4. A prerequisite to operate such shared nanowire-based platform relies on our ability to electrically contact individual metal nanowires and efficiently excite surface plasmon polaritons5 in this information support. In this article, we describe a protocol to bring electrical terminals to chemically-synthesized silver nanowires6 randomly distributed on a glass substrate7. The positions of the nanowire ends with respect to predefined landmarks are precisely located using standard optical transmission microscopy before encapsulation in an electron-sensitive resist. Trenches representing the electrode layout are subsequently designed by electron-beam lithography. Metal electrodes are then fabricated by thermally evaporating a Cr/Au layer followed by a chemical lift-off. The contacted silver nanowires are finally transferred to a leakage radiation microscope for surface plasmon excitation and characterization8,9. Surface plasmons are launched in the nanowires by focusing a near infrared laser beam on a diffraction-limited spot overlapping one nanowire extremity5,9. For sufficiently large nanowires, the surface plasmon mode leaks into the glass substrate9,10. This leakage radiation is readily detected, imaged, and analyzed in the different conjugate planes in leakage radiation microscopy9,11. The electrical terminals do not affect the plasmon propagation. However, a current-induced morphological deterioration of the nanowire drastically degrades the flow of surface plasmons. The combination of surface plasmon leakage radiation microscopy with a simultaneous analysis of the nanowire electrical transport characteristics reveals the intrinsic limitations of such plasmonic circuitry.

Silver nanowires can simultaneously transport electrons and optical information in the form of surface plasmons. A procedure is described here to realize such a shared circuitry and the limitations at propagating both information carriers are evaluated.

Plasmonics is an emerging technology capable of simultaneously transporting a plasmonic signal and an electronic signal on the same information ...

Fabrication of High Contrast Gratings for the Spectrum Splitting Dispersive Element in a Concentrated Photovoltaic System

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve the solar conversion efficiency of a concentrated photovoltaic system. The proposed system will also lower the solar cell cost in the concentrated photovoltaic system by replacing the expensive tandem solar cells with the cost-effective single junction solar cells. The structures and the parameters of high contrast gratings for the dispersive elements were numerically optimized. The large-area fabrication of high contrast gratings was experimentally demonstrated using nanoimprint lithography and dry etching. The quality of grating material and the performance of the fabricated device were both experimentally characterized. By analyzing the measurement results, the possible side effects from the fabrication processes are discussed and several methods that have the potential to improve the fabrication processes are proposed, which can help to increase the optical efficiency of the fabricated devices.

The fabrication of high contrast gratings as the parallel spectrum splitting dispersive element in a concentrated photovoltaic system is demonstrated. Fabrication processes including nanoimprint lithography, TiO2 sputtering and reactive ion etching are described. Reflectance measurement results are used to characterize the optical performance.

制造高对比度光栅的频谱分割色散元件的聚光光伏系统

High contrast gratings are designed and fabricated and its application is proposed in a parallel spectrum splitting dispersive element that can improve ...

Integration of Light Trapping Silver Nanostructures in Hydrogenated Microcrystalline Silicon Solar Cells by Transfer Printing

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly known as plasmonic effects, play an important role. Research in this field has, however, been impeded owing to the difficulty of fabricating devices containing the desired functional metal nanostructures. In order to provide a viable strategy to this issue, we herein show a transfer printing-based approach that allows the quick and low-cost integration of designed metal nanostructures with a variety of device architectures, including solar cells. Nanopillar poly(dimethylsiloxane) (PDMS) stamps were fabricated from a commercially available nanohole plastic film as a master mold. On this nanopatterned PDMS stamps, Ag films were deposited, which were then transfer-printed onto block copolymer (binding layer)-coated hydrogenated microcrystalline Si (&#181;c-Si:H) surface to afford ordered Ag nanodisk structures. It was confirmed that the resulting Ag nanodisk-incorporated &#181;c-Si:H solar cells show higher performances compared to a cell without the transfer-printed Ag nanodisks, thanks to plasmonic light trapping effect derived from the Ag nanodisks. Because of the simplicity and versatility, further device application would also be feasible thorough this approach.

A viable transfer printing-based methodology to introduce plasmonic metal nanostructures in solar cells is described. Using nanopillar poly(dimethylsiloxane) stamps, an Ag-based ordered nanodisk array was integrated with standard hydrogenated microcrystalline Si solar cells, which led to improved device performances due to plasmonic light trapping.

灯光诱杀银纳米结构通过转移印花在氢化微晶硅太阳能电池集成

One of the potential applications of metal nanostructures is light trapping in solar cells, where unique optical properties of nanosized metals, commonly ...

A Fabrication Method for Highly Stretchable Conductors with Silver Nanowires

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of stretchable electronic devices is the preparation of stretchable conductors with great mechanical stability. In this study, we developed a simple fabrication method to chemically solder the contact points between silver nanowire (AgNW) networks. AgNW nanomesh was first deposited on a glass slide via spray coating method. A reactive ink composed of silver nanoparticle (AgNPs) precursors was applied over the spray coated AgNW thin films. After heating for 40 min, AgNPs were preferentially generated over the nanowire junctions to solder the AgNW nanomesh, and reinforced the conducting network. The chemically modified AgNW thin film was then transferred to polyurethane (PU) substrates by casting method. The soldered AgNW thin films on PU exhibited no obvious change in electrical conductivity under stretching or rolling process with elongation strains up to 120%.

A simple synthesis method is used to chemically solder silver nanowire thin film to fabricate highly stretchable and conductive metal conductors.

对于高伸缩的导线与银纳米线制作方法

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of ...

Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic recording of image sequences. The basic components, features, constraints and optimization tips of a 3D-PTV topology consisting of a high-speed camera with a four-view splitter are described and discussed in this article. The technique is applied to the intermediate flow field (5 &#60;x/d &#60;25) of a circular jet at Re &#8776; 7,000. Lagrangian flow features and turbulence quantities in an Eulerian frame are estimated around ten diameters downstream of the jet origin and at various radial distances from the jet core. Lagrangian properties include trajectory, velocity and acceleration of selected particles as well as curvature of the flow path, which are obtained from the Frenet-Serret equation. Estimation of the 3D velocity and turbulence fields around the jet core axis at a cross-plane located at ten diameters downstream of the jet is compared with literature, and the power spectrum of the large-scale streamwise velocity motions is obtained at various radial distances from the jet core.

A three-dimensional particle tracking velocimetry (3D-PTV) system based on a high-speed camera with a four-view splitter is described here. The technique is applied to a jet flow from a circular pipe in the vicinity of ten diameters downstream at Reynolds number Re &#8776; 7,000.

湍流应用三维粒子跟踪测速:一喷流病例

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic ...

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and forging. Adoption of this technique is proceeding despite disagreement concerning the underlying mechanism responsible for EAD. The experimental procedure described herein enables a more explicit study compared to previous EAD research by removing thermal effects, which are responsible for disagreement in interpreting previous EAD results. Furthermore, as the procedure described here enables EAD observation in situ and in real time in a transmission electron microscope (TEM), it is superior to existing post-mortem methods that observe EAD effects post-test. Test samples consist of a single crystal copper (SCC) foil having a free-standing tensile test section of nanoscale thickness, fabricated using a combination of laser and ion beam milling. The SCC is mounted to an etched silicon base that provides mechanical support and electrical isolation while serving as a heat sink. Using this geometry, even at high current density (~3,500 A/mm2), the test section experiences a negligible temperature increase (&#60;0.02 &#176;C), thus eliminating Joule heating effects. Monitoring material deformation and identifying the corresponding changes to microstructures, e.g. dislocations, are accomplished by acquiring and analyzing a series of TEM images. Our sample preparation and in situ experiment procedures are robust and versatile as they can be readily utilized to test materials with different microstructures, e.g., single and polycrystalline copper.

A Novel Method for In Situ Electromechanical Characterization of Nanoscale Specimens

Isolating electrical and thermal effects on electrically assisted deformation (EAD) is very difficult using macroscopic samples. Metallic sample micro- and nanostructures together with a custom test procedure have been developed to evaluate the impact of applied current on the formation without joule heating and evolution of dislocations on these samples.

一种新的方法<em&gt;原位</em&gt;纳米级样品的机电表征

Electrically assisted deformation (EAD) is increasingly being used to improve the formability of metals during processes such as sheet metal rolling and ...

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for Cu(In,Ga)Se2 Solar Cells

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction of degradation mechanisms and prevention of module field failure can consequently decrease investment risks as well as increase the electricity yield. An improved knowledge level can for these reasons significantly decrease the total costs of PV electricity. 
In order to better understand and minimize the degradation of PV modules, the occurring degradation mechanisms and conditions should be identified. This should preferably happen under combined stresses, since modules in the field are also simultaneously exposed to multiple stress factors. Therefore, two 'Combined Stress test with in situ measurement' setups have been designed and constructed. These setups allow the simultaneous use of humidity, temperature, illumination, and electrical biases as independently controlled stress factors on solar cells and minimodules. The setups also allow real-time monitoring of the electrical properties of these samples. This protocol presents these setups and describes the experimental possibilities. Moreover, results obtained with these setups are also presented: various examples about the influence of both deposition and degradation conditions on the stability of thin film Cu(In,Ga)Se2 (CIGS) as well as Cu2ZnSnSe4 (CZTS) solar cells are described. Results on the temperature dependency of CIGS solar cells are also presented.

In Situ Monitoring of the Accelerated Performance Degradation of Solar Cells and Modules: A Case Study for CuIn,GaSe2 Solar Cells

Two &#39;Combined Stress test with in situ measurement&#39; setups, which allow real-time monitoring of accelerated degradation of solar cells and modules, were designed and constructed. These setups allow the simultaneous use of humidity, temperature, electrical biases, and illumination as independently controlled stress factors. The setups and various experiments executed are presented.

就地太阳能电池和模块加速性能退化的监测: 铜 (in, Ga) Se2太阳能电池的实例研究

The levelized cost of electricity (LCOE) of photovoltaic (PV) systems is determined by, among other factors, the PV module reliability. Better prediction ...

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

用斜角沉积法制备高吸收介质的超薄彩色薄膜

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

Conducting Elevated Temperature Normal and Combined Pressure-Shear Plate Impact Experiments Via a Breech-end Sabot Heater System

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The method enables elevated temperature plate-impact experiments aimed towards probing dynamic behavior of materials under thermomechanical extremes, while mitigating several special experimental challenges faced while performing similar experiments using the conventional plate impact approach. Custom adaptations are made to the breech-end of a single-stage gas-gun at Case Western Reserve University; these adaptations include a precision-machined extension piece made from SAE 4340 steel, which is strategically designed to mate the existing gun-barrel while providing a high tolerance match to the bore and keyway. The extension piece contains a vertical cylindrical heater-well, which houses a heater assembly. A resistive coil heater-head, capable of reaching temperatures of up 1200 &#176;C, is attached to a vertical stem with axial/rotational degrees of freedoms; this enables thin metal specimens held at the front-end of a heat-resistant sabot to be heated uniformly across the diameter to the desired test temperatures. By heating the flyer plate (in this case, the sample) at the breech-end of the gun-barrel instead of at the target-end, several critical experimental challenges can be averted. These include: 1) severe changes in the alignment of the target plate during heating due to the thermal expansion of the several constituents of the target holder assembly; 2) challenges that arise due to the diagnostics elements, (i.e., polymer holographic gratings, and optical probes) being too close to the heated target assembly; 3) challenges that arise for target plates with an optical window, where crucial tolerances between the sample, bond layer, and window become increasingly difficult to maintain at high temperatures; 4) in the case of combined compression-shear plate impact experiments, the need for high-temperature resistant diffraction gratings for the measurement of transverse particle velocity at the free surface of the target; and 5) limitations imposed on the impact velocity necessary for unambiguous interpretation of the measured free surface velocity versus time profile due to thermal softening and possibly yielding of the bounding target plates.By utilizing the adaptations mentioned above, we present results from a series of reverse geometry normal plate impact experiments on commercial purity aluminum at a range of sample temperatures. These experiments show decreasing particle velocities in the impacted state, which are indicative of material softening (decrease in post-yield flow stress) with increasing sample temperatures.

Here, we present a detailed protocol of a new approach for conducting elevated temperature reverse normal plate impact, and combined pressure-and-shear plate impact. The approach involves the use of a breech-end resistive coil heater to heat a sample held at the front-end of a heat-resistant sabot to the desired temperature.

采用臀端穿甲弹加热系统进行高温常压联合压力-剪切板冲击试验

A novel approach for conducting normal and/or combined pressure-shear plate impact experiments at test temperatures up to 1000 &#176;C is presented. The ...