The authors gratefully acknowledge funding support from the Ministry of Science and Technology, MOST (project numbers: MOST 104-2218-E-002 -004, MOST 105-2218-E-002-019, MOST 105-2221-E-002 -107 -MY3, MOST 102-2221-E-002 -133 -MY3, and MOST 102-2221-E-002 -088 -MY3).

1. إعداد السطوح التعديل <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> يدويا تلميع قطعة اختبار (جوفاء اسطوانة نحاسية بطول 40 ملم (ل)، يبلغ قطره الخارجي 25 ملم (د س)، ويبلغ قطرها الداخلي 18 ملم (د ط)) لمدة 15 دقيقة باستخدام الصنفرة # 2000 الورق. تنظيف سطح مصقول من قبل الشطف مع الأسيتون يليه الماء DI. </li><li style=";text-align:right;direction:rtl"> ضع قطعة اختبار مصقول في الفرن لمدة 2 ساعة في درجة حرارة ثابتة من 120 ° C. </li><li style=";text-align:right;direction:rtl"> إعداد superhydrophilic شافي 2 جسيمات متناهية الصغر حل باستخدام الخطوات التالية. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> يعد حل A عن طريق خلط 1: 4 نسب الرحى من سيلاني tetraethoxy والمياه DI. إضافة 2 قطرات من 37٪ حمض الهيدروكلوريك المركز إلى حل ألف ويحرك المزيج لمدة 2 ساعة. </li><li style=";text-align:right;direction:rtl"> جعل حل B عن طريق خلط نسبة 1: 3 الرحى من الايثانول والماء DI. </li><li style=";text-align:right;direction:rtl"> خلط 1 مل من محلول ألف إلى 80 مل من محلول B ويقلب لمدة 2 ساعة. </li><li style=";text-align:right;direction:rtl"> إضافة 32 غرام من شافي 2 النانوية (قطرها 40 نانومتر) إلى المحاليل استعدادنشوئها ويقلب لمدة 1 ساعة. </li></ol></li><li style=";text-align:right;direction:rtl"> تزج قطعة اختبار في حل استعداد باستخدام جهاز تراجع طلاء على سرعة 5 مم / دقيقة. الحفاظ على قطعة اختبار المغلفة في الفرن على 120 درجة مئوية لمدة 1 ساعة. </li><li style=";text-align:right;direction:rtl"> إعداد 2 و 4 و 8 أنماط هجينة interlined مع توجهات مختلفة على طول الاتجاه المحوري (كما هو موضح في الشكل رقم 1) باستخدام الخطوات التالية. <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> قناع المنطقة المراد غير المصقول باستخدام الشريط العازل وفقا لعدد المطلوب من interlines مع التوجه السليم (لسطح 2-وتنسيقها في اتجاه 0 درجة، وضبط interlines في المركز والمنطقة superhydrophilic (المنطقة لتكون مغلفة) على الجانب العلوي. من ناحية أخرى، لتوجيه 90 درجة، وضبط الناقلات واحد في الأعلى وآخر في الأسفل ولتوجيه 180 درجة، وضبط منطقة superhydrophilic في الأسفل وinterlines في المركز. وبالمثل، وضبط موقف 4 و 8 أسطح interlined مع مختلف سrientation كما هو مبين في الشكل 1). </li><li style=";text-align:right;direction:rtl"> تزج قطعة اختبار ملثمين في حل استعداد باستخدام جهاز تراجع طلاء، وتراجع في سرعة غمس عالية وارتفاع في سرعة بطيئة من 5 مم / دقيقة. الحفاظ على قطعة اختبار المغلفة في الفرن على 120 درجة مئوية لمدة 1 ساعة. </li><li style=";text-align:right;direction:rtl"> إزالة الشريط العازل من منطقة ملثمين الحصول على العدد المطلوب من interlines مع التوجه السليم. </li></ol></li></ol><img alt="شكل 1" src="/files/ftp_upload/55387/55387fig1.jpg" /> الشكل 1. اختيار الأسطح المختلفة من خلال Interlined. (أ) تخطيطي الأسطح المختلفة من خلال interlined مع توجهات مختلفة. نسبة مساحة سطح النحاس العادي وسطح superhydrophilic هي 1: 1 في جميع الظروف. معايير الاختيار (ب) التوجه. (ج) عرض متساوي القياس من 2 الناقلات سطح الموجهة 0 درجة زاوية. تحديد اتجاه كما الزاوية بين خط الأساس وطلاءخط الوسط من أول نمط ماء من الجانب العلوي، ويتم قياسها في اتجاه عقارب الساعة. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig1large.jpg" target="_blank">الرجاء انقر هنا لمشاهدة نسخة أكبر من هذا الرقم.</a> 2. إجراء التجريبية <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> استخدام الشريط العازل، وإصلاح أنبوب زجاجي واحد في كل قاعدة دائرية من قطعة الاختبار المغلفة. </li><li style=";text-align:right;direction:rtl"> إصلاح أفقيا هذه الجمعية إلى غرفة 140- 140- س × 160 ملم (كما هو موضح في الشكل 2) باستخدام معجون السيليكون وفقا للموقف المطلوب من interlines. </li><li style=";text-align:right;direction:rtl"> ضع-W 550، قطرها 18 مم، و 40 مم طويلة سخان خرطوشة مع طبقة رقيقة من معجون الحراري على المنطقة الدائرية في حفرة من قطعة الاختبار. </li><li style=";text-align:right;direction:rtl"> ربط سخان خرطوشة إلى تيار مباشر (DC) وحدة امدادات الطاقة. </li><li style=";text-align:right;direction:rtl"> مكان T-نوع المزدوجات الحرارية في 8 متباعدة بالتساوي ثقوب 1 ملم، مع أعماق بديلة من 5 ملم و 7 ملم كما هو مبين في الشكل3 ربطها مسجل بيانات. </li><li style=";text-align:right;direction:rtl"> إدراج وإصلاح أجهزة الكشف عن درجة الحرارة المقاومة (RTD)، مكثف ارتداد، وسخان مساعدة في المساحات المتوفرة على الغطاء العلوي. اصلاحها على الحجرة المغلي. </li><li style=";text-align:right;direction:rtl"> ملء 1400 مل من الماء DI في غرفة الغليان بركة. </li><li style=";text-align:right;direction:rtl"> ربط المكثف الراجع إلى غرفة التبريد التي يتم الاحتفاظ في 5 ° C. </li><li style=";text-align:right;direction:rtl"> قبل التجربة، وتغلي بقوة الماء DI في غرفة الغليان تجمع لمدة 30 دقيقة باستخدام سخان مساعدة. </li><li style=";text-align:right;direction:rtl"> الحفاظ على المياه DI في حالة غليان المشبعة باستخدام سخان مساعدة. وفي وقت لاحق، والتبديل على إمدادات الطاقة وتعطي تيار الأولي من 0.1 A. </li><li style=";text-align:right;direction:rtl"> الانتظار لمدة 2 دقيقة من أجل الوصول إلى حالة مستقرة. ثم، زيادة التيار الكهربائي مع الزيادات من 0.3 A. </li><li style=";text-align:right;direction:rtl"> سجل درجة الحرارة في كل مدخلات الطاقة باستخدام مسجل بيانات. تستمر التجربة حتى يتم التوصل إلى تيار أقصى من 4 A. وفي الوقت نفسه، سجل ديناميات فقاعة و<html> أو كل مدخلات الطاقة باستخدام كاميرا CCD وضعت أمام غرفة الغليان المجمع، الذي يركز على قطعة الاختبار. </li></ol><img alt="الشكل 2" src="/files/ftp_upload/55387/55387fig2.jpg" /> الشكل 2. تخطيطي للغرفة بركة الغليان. ترتبط أنابيب الزجاج لكلا الجانبين من اسطوانة النحاس جوفاء مع معجون السيليكون. تم إصلاح هذه إلى غرفة الغليان تجمع مع معجون السيليكون. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig2large.jpg" target="_blank">الرجاء انقر هنا لمشاهدة نسخة أكبر من هذا الرقم.</a> <img alt="الشكل (3)" src="/files/ftp_upload/55387/55387fig3.jpg" /> الرقم 3. الحرارية لتحديد المواقع. توضع 8 المزدوجات الحرارية داخل الثقوب مم 1 محيطي في قطعة الاختبار مكان في قطر 20 مم. يتم إصلاح أعماق بديلة ثقوب قطرها 1MM في 5 ملم و 7 ملم على التوالي./files/ftp_upload/55387/55387fig3large.jpg &quot;الهدف =&quot; _ فارغة &quot;&gt; الرجاء انقر هنا لمشاهدة نسخة أكبر من هذا الرقم. 3. الحد من البيانات <ol style=";text-align:right;direction:rtl"><li style=";text-align:right;direction:rtl"> حساب المدخلات الحرارة (Q) باستخدام المعادلة التالية 19 Q = I V (1) ملاحظة: أنا وV هي المدخلات الحالية في أمبير والجهد في فولت على التوالي. </li><li style=";text-align:right;direction:rtl"> تقدير فقدان الحرارة (خسارة Q) من السطوح الجانبين باستخدام صيغة 19: <img alt="المعادلة 2" src="/files/ftp_upload/55387/55387eq2.jpg" /> (2) ملاحظة: ك هو التوصيل الحراري للنحاس. T 7 ملم وT 5 مم هي متوسط قيم درجة الحرارة في أعماق 7 ملم و 5 ملم، على التوالي؛ Δx (2 ملم) هو الفرق بين أعماق. و <img alt="المعادلة 2B" src="/files/ftp_upload/55387/55387eq2b.jpg" /> هي مساحة المقطع العرضي للاختبار ص<html> IECE. </li><li style=";text-align:right;direction:rtl"> تحديد التدفق الحراري (ف &#39;&#39;) باستخدام الصيغة التالية 19: <img alt="المعادلة 3" src="/files/ftp_upload/55387/55387eq3.jpg" /> (3) ملاحظة: A = π د س ل هو المجال كفافي من قطعة الاختبار. </li><li style=";text-align:right;direction:rtl"> حساب حمى الجدار (باستخدام المعادلة التالية 19: <img alt="المعادلة 4" src="/files/ftp_upload/55387/55387eq4.jpg" /> (4) ملاحظة: T م هو متوسط T 7 ملم وT 5 ملم، وطول قطعة الاختبار، س ص (12.5 مم) دائرة نصف قطرها الخارجي للقطعة الاختبار، دائرة نصف قطرها من قطعة الاختبار ص م (10 ملم) في قياس الثقوب، وT جلس هو على درجة حرارة تشبع المياه DI كما هو مبين في الشكل (4). </li><li style=";text-align:right;direction:rtl"> حساب HTC (α) باستخدام الصيغة التالية 19: pload / 55387 / 55387eq5.jpg &quot;/&gt; (5) </li></ol><img alt="الشكل (4)" src="/files/ftp_upload/55387/55387fig4.jpg" /> الشكل 4. رسم تخطيطي للتحليل درجة الحرارة ستريت. يتم احتساب درجة حرارة الجدار باستخدام متوسط ​​درجة الحرارة المقاسة والمقاومة الحرارية أسطواني المعروفة. <a href="http://ecsource.jove.com/files/ftp_upload/55387/55387fig4large.jpg" target="_blank">الرجاء انقر هنا لمشاهدة نسخة أكبر من هذا الرقم.</a>

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The authors declare that they have no competing financial interests.

The main goal of this investigation was to develop a pool-boiling heat sink for high heat dissipation applications, such as nuclear reactors, boilers, and heat pipes, by introducing the hybrid wettable surface, as described in the protocol section. These surfaces can produce better pool-boiling performances than homogeneous wettable surfaces (hydrophilic and hydrophobic). The improvement in the boiling heat-transfer performance is due to an increase in active nucleation sites and the easy detachment of the formed bubbles...

نظام مكتفية تدفق الحرارة عالية وتوفير التبريد في حدود 10-10 مايو W / سم 2 مطلوب في المجالات الناشئة من الأجهزة الإلكترونية، والدفاع، وإلكترونيات الطيران، وتطوير جهاز النووية. التبريد التقليدية مع الهواء غير كافية لهذه التطبيقات نظرا لمعامل نقل الحرارة المنخفضة (HTC) لكل الظروف free- والقسري الحراري. تقنيات التبريد القائم على مرحلة تغيير، مثل الغليان تجمع وتدفق المغلي، هي جيدة بما فيه الكفاية لإزالة تدفقات ارتفاع الحرارة في حدود 10 - 1000 W / سم 2 1. وبما أن عملية نقل الحرارة على مرحلتين هو متساوي الحرارة، ودرجة حرارة جهاز تبريد ثابتة تقريبا على سطحه. نظرا لاختلاف يذكر في درجات الحرارة على طول السطح، والصدمة الحرارية من الجهاز يمكن القضاء عليها. ومع ذلك، فإن المعلمة الحد الرئيسية في الغليان نقل الحرارة هي الحرارة تدفق النقدي (CHF)، الذي يسبب ارتفاع غير طبيعي في درجة حرارة 2 </sup&gt;. في العقود القليلة الماضية، وقد تم تنفيذ بحوث واسعة لتحسين CHF باستخدام تعديل السطح، nanofluids، وسطح الطلاء 3، 4، 5، 6، 7، 8، 9، 10، 11. ومن بين أساليب مختلفة، تم العثور على مواد الطلاء ليكون أفضل طريقة لتحسين CHF بسبب الزيادة الكبيرة في مساحة السطح. مواد الطلاء بصورة عامة على زيادة نقل الحرارة عن طريق عمل الزعانف، والآثار المسامية، وبلل سطح 12. بلل سطح يلعب دورا هاما في الغليان نقل الحرارة. وتشير دراسات سابقة أنه في ظروف الحرارة تدفق أقل، والسطح مسعور يظهر HTC أفضل نظرا لالتنوي في وقت مبكر. ومع ذلك، فيارتفاع تدفق الحرارة، ومفرزة من الفقاعات تشكلت بطيئة نظرا لتقارب منخفضة من المياه نحو السطح. وهذا يؤدي إلى التحام فقاعة ويؤدي إلى انخفاض CHF 3. من ناحية أخرى، على سطح ماء ينتج CHF أعلى، بسبب انفصال سريع من الفقاعات تشكلت، لكنه يعطي HTC أقل في تدفقات درجة حرارة منخفضة، وذلك بسبب التأخير في فقاعة التنوي 13. تظهر هياكل هجينة تعزيز ملحوظا في الغليان نقل الحرارة لجميع تدفقات الحرارة بسبب التأثير المشترك لللا مائية وhydrophilicity 14 و 15 و 16. هسو وآخرون. أنتج سطح قابل للبلل غير متجانسة بواسطة طلاء superhydrophilic سي النانوية على سطح النحاس ملثمين. حققوا نسب بلل مختلفة من خلال تغيير الوقت الطلاء. بداية الغليان وقع في وقت سابق على أسطح غير متجانسة بالمقارنة مع حسطح omogeneous، مما ادى الى تراجع كبير في جدار حمى 17. جو وآخرون. أجريت nucleate المغلي الدراسات نقل الحرارة على الأسطح ترطيب ماء، مسعور، وغير متجانسة. وتألفت لسطح التبول غير متجانسة من النقاط منقوشة مسعور على سطح ماء. لأنهم وصلوا HTCs أعلى ونفس CHF لسطح متجانسة بالمقارنة مع سطح ماء. تحسن في الغليان نقل الحرارة يعتمد بشكل مباشر على عدد من النقاط على السطح وعلى الظروف الغليان 18. في هذه الدراسة، تم إنتاج المحوري أنماط القابلة للبلل الهجينة على سطح النحاس اسطوانية باستخدام تقنية تراجع الطلاء. أجريت السباحة المغلي الدراسات نقل الحرارة لتحديد الآثار المترتبة على عدد من interlines وتوجه نمط قابل للبلل الهجين. وقد تم تحليل الغليان تدفق الحرارة، HTC، وديناميات فقاعة لركائز كل المغلفة، ونحنإعادة مقارنة مع الركيزة النحاس.

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pool-boiling heat-transfer enhancement on cylindrical surfaces with hybrid wettable patterns

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the hybrid wettable pattern. Hybrid wettable patterns were produced by coating superhydrophilic SiO2 on a masked, hydrophobic, cylindrical copper surface. Using de-ionized (DI) water as the working fluid, pool-boiling heat-transfer studies were conducted on the different surface-treated copper cylinders of a 25-mm diameter and a 40-mm length. The experimental results showed that the number of interlines and the orientation of the hybrid wettable pattern influenced the wall superheat and the HTC. By increasing the number of interlines, the HTC was enhanced when compared to the plain surface. Images obtained from the charge-coupled device (CCD) camera indicated that more bubbles formed on the interlines as compared to other parts. The hybrid wettable pattern with the lowermost section being hydrophobic gave the best heat-transfer coefficient (HTC). The experimental results indicated that the bubble dynamics of the surface is an important factor that determines the nucleate boiling.

وأجريت التجارب نقل الحرارة الغليان تجمع على سطح أسطواني قابل للبلل الهجين باستخدام الإعداد التجريبية التي هو مبين في الشكل (5) التخطيطي. وأوضح الإجراء التجريبي الغليان تجمع في الخطوة 2 من قسم البروتوكول ونفذت بنجاح أثناء التحقيق في تأثير ع?...

Watch this Scientific Journal Video about Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns at JoVE.com

Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

أجريت تجارب نقل الحرارة الغليان تجمع خارج لمراقبة آثار أنماط القابلة للبلل الهجينة على معامل نقل الحرارة (HTC). المعلمات التحقيق هي عدد interlines والتوجه نمط من سطح قابل للبلل تعديلها.

تعزيز بركة الغليان نقل الحرارة على أسطواني السطوح مع أنماط قابل للبلل الهجين

In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the ...

pool-boiling-heat-transfer-enhancement-on-cylindrical-surfaces-with

Research

JoVE Journal

Engineering

8.9K Views.  National Taiwan University.  أجريت تجارب نقل الحرارة الغليان تجمع خارج لمراقبة آثار أنماط القابلة للبلل الهجينة على معامل نقل الحرارة (HTC). المعلمات التحقيق هي عدد interlines والتوجه نمط من سطح قابل للبلل تعديلها. 

Video: Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns

Micropunching Lithography for Generating Micro- and Submicron-patterns on Polymer Substrates

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of low weight, easy tailoring of properties and a wide spectrum of applications2,3. Due to sensitivity of conducting polymers to environmental conditions (e.g., air, oxygen, moisture, high temperature and chemical solutions), lithographic techniques present significant technical challenges when working with these materials4. For example, current photolithographic methods, such as ultra-violet (UV), are unsuitable for patterning the conducting polymers due to the involvement of wet and/or dry etching processes in these methods. In addition, current micro/nanosystems mainly have a planar form5,6. One layer of structures is built on the top surfaces of another layer of fabricated features. Multiple layers of these structures are stacked together to form numerous devices on a common substrate. The sidewall surfaces of the microstructures have not been used in constructing devices. On the other hand, sidewall patterns could be used, for example, to build 3-D circuits, modify fluidic channels and direct horizontal growth of nanowires and nanotubes.
A macropunching method has been applied in the manufacturing industry to create macropatterns in a sheet metal for over a hundred years. Motivated by this approach, we have developed a micropunching lithography method (MPL) to overcome the obstacles of patterning conducting polymers and generating sidewall patterns. Like the macropunching method, the MPL also includes two operations (Fig. 1): (i) cutting; and (ii) drawing. The "cutting" operation was applied to pattern three conducting polymers4, polypyrrole (PPy), Poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT) and polyaniline (PANI). It was also employed to create Al microstructures7. The fabricated microstructures of conducting polymers have been used as humidity8, chemical8, and glucose sensors9. Combined microstructures of Al and conducting polymers have been employed to fabricate capacitors and various heterojunctions9,10,11. The "cutting" operation was also applied to generate submicron-patterns, such as 100- and 500-nm-wide PPy lines as well as 100-nm-wide Au wires. The "drawing" operation was employed for two applications: (i) produce Au sidewall patterns on high density polyethylene (HDPE) channels which could be used for building 3D microsystems12,13,14, and (ii) fabricate polydimethylsiloxane (PDMS) micropillars on HDPE substrates to increase the contact angle of the channel15.

A micropunching lithography approach is developed to generate micro- and submicron-patterns on top, sidewall and bottom surfaces of polymer substrates. It overcomes the obstacles of patterning conducting polymers and generating sidewall patterns. This method allows rapid fabrication of multiple features and is free of aggressive chemistry.

Micropunching الطباعة الحجرية لتوليد الصغرى، وأنماط Submicron، على ركائز بوليمر

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 19771. They offer the advantages of ...

Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM, other properties such as local electronic states, ion diffusion coefficient and surface potential can also be investigated17-22. In this work, electrochemical measurements, Raman spectroscopy, and SPM were used in conjunction with a novel test electrode platform that consists of a Ni mesh electrode embedded in an yttria-stabilized zirconia (YSZ) electrolyte. Cell performance testing and impedance spectroscopy under fuel containing H2S was characterized, and Raman mapping was used to further elucidate the nature of sulfur poisoning. In situ Raman monitoring was used to investigate coking behavior. Finally, atomic force microscopy (AFM) and electrostatic force microscopy (EFM) were used to further visualize carbon deposition on the nanoscale. From this research, we desire to produce a more complete picture of the SOFC anode.

We present a unique platform for characterizing electrode surfaces in solid oxide fuel cells (SOFCs) that allows simultaneous performance of multiple characterization techniques (e.g. in situ Raman spectroscopy and scanning probe microscopy alongside electrochemical measurements). Complementary information from these analyses may help to advance toward a more profound understanding of electrode reaction and degradation mechanisms, providing insights into rational design of better materials for SOFCs.

التحقيق ورسم الخرائط أسطح الكهربائي في خلايا الوقود الصلبة أكسيد

Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen ...

Fabrication of Nano-engineered Transparent Conducting Oxides by Pulsed Laser Deposition

Nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas allows the deposition of metal oxides with tunable morphology, structure, density and stoichiometry by a proper control of the plasma plume expansion dynamics. Such versatility can be exploited to produce nanostructured films from compact and dense to nanoporous characterized by a hierarchical assembly of nano-sized clusters. In particular we describe the detailed methodology to fabricate two types of Al-doped ZnO (AZO) films as transparent electrodes in photovoltaic devices: 1) at low O2 pressure, compact films with electrical conductivity and optical transparency close to the state of the art transparent conducting oxides (TCO) can be deposited at room temperature, to be compatible with thermally sensitive materials such as polymers used in organic photovoltaics (OPVs); 2) highly light scattering hierarchical structures resembling a forest of nano-trees are produced at higher pressures. Such structures show high Haze factor (&gt;80%) and may be exploited to enhance the light trapping capability. The method here described for AZO films can be applied to other metal oxides relevant for technological applications such as TiO2, Al2O3, WO3 and Ag4O4.

We describe the experimental method to deposit nanostructured oxide thin films by nanosecond Pulsed Laser Deposition (PLD) in the presence of a background gas. By using this method Al-doped ZnO (AZO) films, from compact to hierarchically structured as nano-tree forests, can be deposited.

تلفيق نانو هندسيا إجراء أكاسيد شفافة من ترسب الليزر النبضي

Nanosecond Pulsed  Laser Deposition (PLD) in the presence of a background gas allows the deposition  of metal oxides with tunable morphology, structure, ...

High-speed Particle Image Velocimetry Near Surfaces

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The complex nature of these flows may be studied using particle image velocimetry (PIV), a laser-based imaging technique for optically accessible flows. Though many forms of PIV exist that extend the technique beyond the original planar two-component velocity measurement capabilities, the basic PIV system consists of a light source (laser), a camera, tracer particles, and analysis algorithms. The imaging and recording parameters, the light source, and the algorithms are adjusted to optimize the recording for the flow of interest and obtain valid velocity data. 
Common PIV investigations measure two-component velocities in a plane at a few frames per second. However, recent developments in instrumentation have facilitated high-frame rate (&gt; 1 kHz) measurements capable of resolving transient flows with high temporal resolution. Therefore, high-frame rate measurements have enabled investigations on the evolution of the structure and dynamics of highly transient flows. These investigations play a critical role in understanding the fundamental physics of complex flows.
A detailed description for performing high-resolution, high-speed planar PIV to study a transient flow near the surface of a flat plate is presented here. Details for adjusting the parameter constraints such as image and recording properties, the laser sheet properties, and processing algorithms to adapt PIV for any flow of interest are included.

A procedure for studying transient flows near boundaries using high-resolution, high-speed particle image velocimetry (PIV) is described here. PIV is a non-intrusive measurement technique applicable to any optically accessible flow by optimizing several parameter constraints such as the image and recording properties, the laser sheet properties, and analysis algorithms.

عالي السرعة الجسيمات Velocimetry صورة قرب السطوح

Multi-dimensional and transient flows play a key role in many areas of science, engineering, and health sciences but are often not well understood. The ...

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms.
In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station.

A detailed procedure for surface doping of Silicon interfaces is provided. The ultra-shallow surface doping is demonstrated by using phosphorus containing monolayers and rapid annealing process. The method can be used for doping of macroscopic area surfaces as well as nanostructures.

الاتصال أحادي الطبقة المنشطات من السيليكون السطوح والأسلاك المتناهية الصغر عن طريق المركبات الفوسفورية العضوية

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra ...

Evanescent Field Based Photoacoustics: Optical Property Evaluation at Surfaces

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. Optical property evaluation of thin films and the surfaces of bulk materials is an important step in understanding new optical material systems and their applications. The method presented can estimate thickness, refractive index, and use absorptive properties of materials for detection. This metrology system uses evanescent field-based photoacoustics (EFPA), a field of research based upon the interaction of an evanescent field with the photoacoustic effect. This interaction and its resulting family of techniques allow the technique to probe optical properties within a few hundred nanometers of the sample surface. This optical near field allows for the highly accurate estimation of material properties on the same scale as the field itself such as refractive index and film thickness. With the use of EFPA and its sub techniques such as total internal reflection photoacoustic spectroscopy (TIRPAS) and optical tunneling photoacoustic spectroscopy (OTPAS), it is possible to evaluate a material at the nanoscale in a consolidated instrument without the need for many instruments and experiments that may be cost prohibitive.

Here we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. This technique evanescent field-based photoacoustics can be used to create a photoacoustic metrology system to estimate materials&#39; thicknesses, bulk and thin film refractive indices, and explore their optical properties.

زائل الميدان Photoacoustics استنادا: تقييم العقارات للبصريات على السطوح

Here, we present a protocol to estimate material and surface optical properties using the photoacoustic effect combined with total internal reflection. ...

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO&#903;, -H2C&#903;, -O&#903;, -CO&#903; radicals. During the degradation process, CO and CO2 were also produced.

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.

تطور السيليكا طلاءات الجسيمات النانوية البوليستر على السطوح المعرضة لأشعة الشمس

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, ...

Measurements of Local Instantaneous Convective Heat Transfer in a Pipe - Single and Two-phase Flow

This manuscript provides step by step description of the manufacturing process of a test section designed to measure the local instantaneous heat transfer coefficient as a function of the liquid flow rate in a transparent pipe. With certain amendments, the approach is extended to gas-liquid flows, with a particular emphasis on the effect of a single elongated (Taylor) air bubble on heat transfer enhancement. A non-invasive thermography technique is applied to measure the instantaneous temperature of a thin metal foil heated electrically. The foil is glued to cover a narrow slot cut in the pipe. The thermal inertia of the foil is small enough to detect the variation in the instantaneous foil temperature. The test section can be moved along the pipe and is long enough to cover a considerable part of the growing thermal boundary layer.
At the beginning of each experimental run, a steady state with a constant water flow rate and heat flux to the foil is attained and serves as the reference. The Taylor bubble is then injected into the pipe. The heat transfer coefficient variations due to the passage of a Taylor bubble propagating in a vertical pipe is measured as function of the distance of the measuring point from the bottom of the moving Taylor bubble. Thus, the results represent the local heat transfer coefficients. Multiple independent runs preformed under identical conditions allow accumulating sufficient data to calculate reliable ensemble-averaged results on the transient convective heat transfer. In order to perform this in a frame of reference moving with the bubble, the location of the bubble along the pipe has to be known at all times. Detailed description of measurements of the length and of the translational velocity of the Taylor bubbles by optical probes is presented.

This manuscript describes methods aimed at measuring the local instantaneous convective heat transfer coefficients in a single or two-phase pipe flow. A simple optical method to determine the length and the propagation velocity of an elongated (Taylor) air bubble moving at a constant velocity is also presented.

قياسات لنقل الحرارة الحمل الحراري لحظية المحلية في أنبوب--تدفق واحد ومرحلتين

This manuscript provides step by step description of the manufacturing process of a test section designed to measure the local instantaneous heat transfer ...

Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl dimethyl azlactone) (PGMA-b-PVDMA), are presented. Due to the high reactivity of azlactone groups towards amine, thiol, and hydroxyl groups, PGMA-b-PVDMA surfaces can be modified with secondary molecules to create chemically or biologically functionalized interfaces for a variety of applications. Previous reports of patterned PGMA-b-PVDMA interfaces have used traditional top-down patterning techniques that generate non-uniform films and poorly controlled background chemistries. Here, we describe customized patterning techniques that enable precise deposition of highly uniform PGMA-b-PVDMA films in backgrounds that are chemically inert or that have biomolecule-repellent properties. Importantly, these methods are designed to deposit PGMA-b-PVDMA films in a manner that completely preserves azlactone functionality through each processing step. Patterned films show well-controlled thicknesses that correspond to polymer brushes (~90 nm) or to highly crosslinked structures (~1-10 &#956;m). Brush patterns are generated using either the parylene lift-off or interface directed assembly methods described and are useful for precise modulation of overall chemical surface reactivity by adjusting either the PGMA-b-PVDMA pattern density or the length of the VDMA block. In contrast, the thick, crosslinked PGMA-b-PVDMA patterns are obtained using a customized micro-contact printing technique and offer the benefit of higher loading or capture of secondary material due to higher surface area to volume ratios. Detailed experimental steps, critical film characterizations, and trouble-shooting guides for each fabrication method are discussed.

Surface fabrication methods for patterned deposition of nanometer thick brushes or micron thick, crosslinked films of an azlactone block co-polymer are reported. Critical experimental steps, representative results, and limitations of each method are discussed. These methods are useful for creating functional interfaces with tailored physical features and tunable surface reactivity.

اختﻻق السطوح المتفاعلة مع مثل الفرشاة وأفلام كروسلينكيد فونكتيوناليزيد أزلاكتوني كتلة المشارك البوليمرات

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl ...

Uncoupling Coriolis Force and Rotating Buoyancy Effects on Full-Field Heat Transfer Properties of a Rotating Channel

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that characterize the transport phenomena in a rotating channel are identified via the parametric analysis of the momentum and energy equations referring to a rotating frame of reference. Based on these dimensionless flow equations, an experimental strategy that links the design of the test module, the experimental program and the data analysis is formulated with the attempt to reveal the isolated Coriolis-force and buoyancy effects on heat transfer performances. The effects of Coriolis force and rotating buoyancy are illustrated using the selective results measured from rotating channels with various geometries. While the Coriolis-force and rotating-buoyancy impacts share several common features among the various rotating channels, the unique heat transfer signatures are found in association with the flow direction, the channel shape and the arrangement of heat transfer enhancement devices. Regardless of the flow configurations of the rotating channels, the presented experimental method enables the development of physically consistent heat transfer correlations that permit the evaluation of isolated and interdependent Coriolis-force and rotating-buoyancy effects on the heat transfer properties of rotating channels.

Here, we present an experimental method for decoupling the interdependent Coriolis-force and rotating-buoyancy effects on full-field heat transfer distributions of a rotating channel.

قوة كوريوليس يفصل وآثار الطفو الدورية على الحرارة كامل-ميدان نقل خصائص قناة الدورية

An experimental method for exploring the heat transfer characteristics of an axially rotating channel is proposed. The governing flow parameters that ...