This study produced and analyzed shaped tungsten wire tips formed through electrochemical etching. Specifically, the cone length and the radius of curvature of the tip were analyzed. Having the tips move dynamically through an electrolytic solution, such as potassium hydroxide, and tuning the initial starting depth of the tungsten wire along with the dynamic speed of the tungsten wire as it passed throughout the solution allowed various types of tip profiles to be produced. The tip's radius of curvature was able to be reproduced with an accuracy between 88 - 92 %. The method provided would be applicable for the production of various styles of liquid-metal ion source (LMIS) probes and scanning probe microscope (SPM) tips.

Dans la galvanisation à chaud, les aciers sont protégés contre la corrosion par une mince couche de zinc obtenue par immersion dans un bain d’alliage de zinc. Avant ce processus, les tôles d'acier subissent un recuit de recristallisation afin d'éliminer l’écrouissage après laminage à froid. Les conditions de recuit utilisées réduisent le film d'oxyde de fer natif, ce qui favorise la mouillabilité de la surface de l'acier par le zinc liquide. Cependant, les nouveaux aciers à haute résistance contiennent des quantités importantes d'éléments d’addition, tels que le silicium et le manganèse. Ces élements diffusent à la surface de l'acier pendant le recuit de recristallisation et forment des particules ou des films d'oxyde par oxydation sélective externe. Si le fer pur est bien mouillé par le zinc liquide, ces oxydes ne le sont pas et leur présence à la surface peut entraîner des défauts dans le revêtement final.Pour étudier l'influence de la taille et de la distribution des oxydes sur le mouillage par le métal liquide, nous avons étudié un mouillage non réactif du plomb liquide sur une surface hétérogène texturée Fe / silice en utilisant la technique de chute de goutte.Ces surfaces ont été conçues par dépôt chimique en phase vapeur assisté par plasma, suivi d'un procédé photolithographique.Après l'impact, la goutte s'étend jusqu'à son diamètre d'étalement maximal. S’ensuit une phase de recule de la goutte. Pendant son recul, la goutte est plus ou moins retenue, en fonction du taux de couverture de silice, sur le fer pur: phénomène d’accrochage-glissement. Sur les surfaces à faible teneur en silice, ce phénomène entraîne une déformation de la forme de la goutte qui est plus allongée dans un sens et quelquefois à la division de la goutte.Il a été démontré que le mouillage est affecté principalement par la fraction de surface de la silice.Enfin, nous avons modélisé les différentes phases de l'étalement de la goutte sur ces surfaces hétérogènes. Des modèles de littérature ont été revus et adaptés et nous avons proposé des modèles macroscopiques de l'oscillation de la goutte pendant son étalement. / In hot-dip galvanizing, steel sheets are protected against corrosion by a thin layer of zinc obtained by immersion in a zinc alloy bath. Before this process, the steel sheets undergo recrystallization annealing to eliminate stresses after cold-rolling. The annealing conditions used reduce the native iron oxide film, which promotes the wettability of the steel surface with liquid zinc. However, new high-strength steels contain significant quantities of addition elements, such as silicon and manganese. These elements diffuse on the surface of the steel sheets during recrystallization annealing and form oxide particles or films by selective external oxidation. If pure iron is well wet with liquid zinc, these oxides are not and their presence on the surface can lead to defects in the final coating.To study the influence of oxide size and their distribution on liquid metal wetting, we studied a non-reactive wetting of liquid lead on a heterogeneous Fe / silica textured surface using the dispensed technique.These surfaces were designed by plasma-assisted chemical vapour deposition followed by a photolithographic process.After impact, the drop extends to its maximum spreading diameter. This is followed by a phase of drop receding. During this, the drop is more or less retained, depending on the silica coverage rate, on the pure iron: stick-slip motion. On surfaces with low silica content, this phenomenon causes a deformation of the drop shape which is more elongated in one direction and sometimes at the division of the drop.We showed that wetting is mainly affected by the surface fraction of silica.Finally, we modelled the different phases of drop spreading on these heterogeneous surfaces. Literature models were reviewed and adapted and macroscopic models of the oscillation of the drop during its spreading were proposed.

Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 289-295. / by Bahman Atefi. / Sc.D.

Thesis. 1978. M.S.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / M.S.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第18609号 / エネ博第305号 / 新制||エネ||62(附属図書館) / 31509 / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)教授 小西 哲之, 教授 星出 敏彦, 教授 岸本 泰明 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21764号 / 工博第4581号 / 新制||工||1714(附属図書館) / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 功刀 資彰, 教授 横峯 健彦, 教授 村上 定義 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

In this work the susceptibility of Fe-10Cr-4Al steel to liquid metal embitterment (LME)in low oxygen environment was investigated. slow strain rate testing (SSRT) wereconducted on 10-4 FeCrAl steel in a stagnant lead from 340-480◦C, lead-bismutheutectic (LBE) from 140-450◦C and lead-bismuth mixture at 375◦C with increasingbismuth content from 0.1wt%-40wt%. The results showed that in the stagnant leadenvironment the FeCrAl steel showed no sign of LME with all samples being subjectedto around 25% strain before final break. In LBE the samples were affected by LMEespecially at 350-400◦C. The total elongation to failure reduced in LBE from 25%to 13.1% and a ductility trough from 190-400◦C was observed. In the lead-bismuthmixture there was a reduction in ductility at 5wt% going from 25% to 20% totalelongation, at 15wt% going from 20% to 16% total elongation and at 30wt% going from16% to 13% total elongation. / I det här arbetet har stålet Fe-10Cr-4Al känslighet till liquidmetal embrittlemnt(LME)i låga syre miljöer av flytande bly, mellan 340-480 °C, och Bly/Vismut eutektisk (LBE),mellan 140-450 °C, undersökts. En stegvis ökning av Vismut halten i flytande blygenfördes också från 0.1 wt% Bi till 40 wt% Bi med en fast temperatur på 375 °C.Resultaten från dessa experiment visade att i ren bly miljö så visade stålet Fe-10Cr-4Al inga tecken på LME, alla prover gick till brott runt 25% strain. I LBE blev ståletsvårt på verkat av LME, framför allt inom temperaturer intervallet 350-400 °C. Dentotala förlängningen av proverna blev här reducerat från 25% ner till 13.1% och en klarduktilitets tråg mellan 190-400 °C kunde observeras. I experimenten med gradvisökande Vismut halt observerades markanta nedgångar i stålets duktilitet vid 5 wt%Bi då den droppar från 25% till 20% förlängning, nästa dropp observerades vid 15 wt%Bi, 20%-16% och vid 30 wt% Bi med ett reduktion från 16% till 13%.

Multi-component soft materials offer innovative solutions for traditional and emerging technologies by possessing unique combinations of tunable functionality and adaptive mechanical response. These materials often incorporate functional inclusions such as metals or ceramics in elastomers to create deformable composite structures with high thermal or electrical conductivities, magnetic material response, or stimuli-responsive shape and rigidity tuning. In recent years, these materials have become enabling for wearable electronics and soft machines which has led to the development of new material architectures that provide advanced functionalities while maintaining a low mechanical modulus and high extensibility. In this work, we develop methods for the fabrication and utilization of advanced material architectures which integrate room temperature liquid metals (LM), low melting point alloys (LMPA), and magnetic powders and fluids with soft elastomers to introduce multifunctionality to electronic and machine systems. LM-elastomer composites which have high thermal and electrical conductivities are enabling for heat transfer applications and soft, extensible wiring for wearable electronics and soft robots. These materials have been utilized to create emerging devices such as electronics that are capable of improving human health and efficiency, as well as robots capable of adapting their functions based on environmental need. One possible area where LM composites could be applied is in marine environments, where wearable electronics can improve safety for divers, and soft machines could be utilized for underwater exploration. In Chapter 2, we provide the first study to quantify the effects of underwater aging in freshwater and saltwater environments on the important mechanical and functional properties of LM composites for long-term underwater use. It is found that LM composites are largely resistant to changes in their mechanical properties, as well as both thermal and electrical functionality due to long-term underwater aging. In Chapter 3, we introduce a new chemical approach for the tough bonding of LM composites to diverse substrates, which increases adhesion by up to 100x, improving the integration of these materials with rigid electronics. It is shown that the fracture energy and thermal conductivity of these materials can be tuned by controlling the size and volume loading of the LM inclusions. The utility of this method is then shown through the permanent bonding of LM composites to rigid electronics for use as thermal interface materials. \\ Chapter 4 introduces a multi-component shape morphing material that leverages an LMPA endoskeleton and soft LM resistive heaters to produce rapid (< 0.1 s) and reversible shape change. The morphing material utilizes a unique 'reversible plasticity' mechanism enabled by patterned kirigami cuts that allows for instantaneous shape fixing into load bearing shapes without the need for sustained power. The material properties are enabling for the creation of shape morphing robots, which we show through by integration of on board power and control to create a multi-modal morphing drone capable of land and air transport as well as through an underwater machine that can be reversibly deployed to obtain cargo. For magnetic elastomers, the magneto-mechanical properties of state-of-the-art magnetorheological elastomers (MREs) with diverse structures are studied. These materials have long been studied for their ability to rapidly tune stiffness in the presence of a magnetic field. Chapter 5 introduces a new form of hybrid MRE material architecture which utilizes a combination of magnetic powders and fluids to achieve high magnetic permeability and low stiffness for wearable electronic applications. The zero-field magneto-mechanical properties of MREs with rigid particles, magnetic fluids, and a combination of the two are studied. The inclusions are modeled through an Eshelby analysis which demonstrates magnetic fluids can be utilized to increase magnetic response while decreasing the stiffness of the composite material. The stiffness tuning capabilities of these material architectures are then explored in Chapter 6, where we introduce a predictive model that captures the stiffness tuning response of MREs across diverse microstructures and compositions. This model guides the creation of materials with rapid (~ 20 ms) and extreme stiffness tuning (70x) which we utilize to create a soft adaptive gripper capable of handling objects of diverse geometries. / Doctor of Philosophy / Multi-component soft materials offer innovative solutions for traditional and emerging technologies by possessing unique combinations of tunable functionality and adaptive mechanical properties. These materials often incorporate functional inclusions such as metals or ceramics in elastomers in order to create deformable composite structures with high thermal or electrical conductivities, magnetic material response, or user-controlled shape morphing and stiffness change. In recent years, these materials have become enabling for wearable electronics and soft machines which has led to the development of new materials that provide advanced functionalities while maintaining a low stiffness and high extensibility. In this work, we develop methods for the fabrication and utilization of advanced materials that integrate room temperature liquid metals (LM), low melting point alloys (LMPA), and magnetic powders and fluids with soft elastomers to introduce multifunctionality to electronic and machine systems. LM-elastomer composites which have high thermal and electrical conductivities are enabling for heat transfer and stretchable electronic applications for wearable electronics and soft robots. These materials have been utilized to create emerging devices such as electronics that are capable of improving human health and efficiency, as well as robots capable of adapting their functions based on environmental need. One possible area where LM composites could be applied is in marine environments, where wearable electronics can improve safety for divers, and soft robots could be utilized for underwater exploration. In Chapter 2, we provide the first study to quantify the effects of underwater aging in freshwater and saltwater environments on the important mechanical and functional properties of LM composites for long-term underwater use. It is found that LM composites are largely resistant to changes in their mechanical properties, as well as both thermal and electrical functionality due to long-term underwater aging. In Chapter 3, we introduce a new chemical approach for the tough bonding of LM composites to diverse substrates, which increases adhesion by up to 100x, improving the integration of these materials with rigid electronics. It is shown that the adhesion and thermal conductivity of these materials can be tuned by controlling the size and volume loading of the LM inclusions. The utility of this method is then shown through the permanent bonding of LM composites to rigid electronics for use as thermal interface materials. Chapter 4 introduces a multi-component shape morphing material that leverages an LMPA endoskeleton and soft LM resistive heaters to produce rapid (< 0.1 s) and reversible shape change. The morphing material utilizes a unique 'reversible plasticity' mechanism enabled by patterned kirigami cuts that allows for instantaneous shape fixing into load bearing shapes without the need for sustained power. The material properties are enabling for the creation of shape morphing robots, which we show through by integration of on board power and control to create a multi-modal morphing drone capable of land and air transport as well as through an underwater machine that can be reversibly deployed to obtain cargo. For magnetic elastomers, the magnetic and mechanical properties of state-of-the-art magnetorheological elastomers (MREs) with diverse structures are studied. These materials have long been studied for their ability to rapidly change stiffness in the presence of a magnetic field. Chapter 5 introduces a new form of hybrid MRE material architecture which utilizes a combination of magnetic powders and fluids to achieve exceptional magnetic properties and low stiffness for wearable electronic applications. The mechanical properties of MREs with rigid particles, magnetic fluids, and a combination of the two are studied. The inclusions are modeled through a mechanical analysis which demonstrates magnetic fluids can be utilized to increase magnetic character while decreasing the stiffness of the composite material. The stiffness tuning capabilities of these material architectures are then explored in Chapter 6, where we introduce a predictive model that captures the stiffness tuning response of MREs across diverse microstructures and compositions. This model guides the creation of materials with rapid (~ 20 ms) and extreme stiffness tuning (70x) which we utilize to create a soft adaptive gripper capable of handling objects of diverse geometries.

No description available.