Download or read book Etude par spectroscopie m canique et microscopie lectronique en transmission de la stabilit thermique de verres m talliques massifs written by Bertrand Van de Moortèle and published by . This book was released on 2002 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Etude par spectroscopie mécanique et microscopie électronique en transmission de la stabilité autour de la température de transition vitreuse (Tg). Cette propriété permet ainsi de mettre en forme des objets à basse température sans appliquer d'efforts trop importants. Des trempes ultra-rapides depuis l'état liquide sont généralement nécessaires pour obtenir des métaux amorphes de seulement quelques micromètres d'épaisseur. Depuis un peu plus de 10 ans, des compositions particulières d'alliages ont permis d'obtenir des verres métalliques massifs (i.e. quelques dizaines de mm d'épaisseur). Néanmoins, les matériaux obtenus sont fortement 'hors équilibre' auront tendance à rejoindre des états thermodynamiques plus stables lors de leur mise en forme à une température voisine de Tg. Les buts de cette, outre de caractériser et de modéliser les propriétés mécaniques de l'état amorphe, ont été l'observation des différentes étapes menant à cette cristallisation et ceci dans différents verres métalliques massifs en reliant ceci aux modifications des propriétés mécaniques.
Download or read book Stabilit physico chimique et propri t s m caniques d un verre m tallique massif ZrCuAlNi de l ambiante 600 c written by Marie-Laure Vaillant and published by . This book was released on 2003 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: La synthèse de verres métalliques sous forme massive est récente et il est encore parfois difficile d'obtenir des matériaux totalement amorphes. Nous avons pu mettre en évidence dans le verre métallique massif Zr55Cu30Al10Ni5 le rôle déterminant de l'oxygène dans la germination de cristallites dendritiques dont une structure cristallographique a été proposée. La stabilité en température ainsi que la cristallisation (phases formées, cinétique) de la matrice vitreuse ont été étudiées par différentes techniques : DSC, mesure de résistivité ou mesure in situ du module d'Young à chaud. Certaines propriétés mécaniques de ce verre ont été mesurées à température ambiante et à chaud : Dureté, modules d'élasticité (par échographie ultrasonore et spectroscopie mécanique), comportement au rayage, fluage. Les applications des verres métalliques massifs sont encore assez restreintes mais leurs propriétés remarquables permettent d'espérer une utilisation beaucoup plus étendue dans les années à venir.
Download or read book Etude des relations entre caract ristiques structurales et dissipation en vibration dans les verres m talliques massifs written by Cédric Haon and published by . This book was released on 2006 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: L’objectif de ce travail était d’évaluer l’amortissement de l’énergie mécanique des verres métalliques massifs, en utilisant un matériau modèle de composition Pd40Ni10Cu30P20, et d’analyser les mécanismes qui en sont responsables, dans le domaine du kilohertz à température ambiante pour un résonateur mécanique de géométrie simplifiée dont la dimension caractéristique est de l’ordre du millimètre. Dans ces conditions opératoires, la dissipation est liée à la thermoélasticité. Ce phénomène correspond au transport de chaleur résultant de la déformation élastique induite par la vibration. L’évaluation des potentialités de ces alliages métalliques amorphes en tant que résonateurs a nécessité la réalisation d’échantillons tests de forme adaptée ; cette étape préliminaire a été effectuée par coulée à la forme suivie de différentes opérations telles que des traitements thermiques et une étape d’usinage et de polissage. Le facteur de qualité Q, paramètre caractéristique de la dissipation en vibration, a ensuite été déterminé à partir de la mesure du décrément logarithmique de l’amplitude de vibration d’un échantillon de forme disque-tige mis en résonance suite à un choc. Les recuits au voisinage de la température de transition vitreuse ont conduit à augmenter le facteur de qualité de 0,3 million à 0,8 million. Cette amélioration n’est pas directement corrélée à la relaxation structurale du verre, caractérisée par diverses techniques (ATD, dilatométrie, spectroscopie mécanique...), qui se produit au cours du recuit. C’est la relaxation des contraintes résiduelles, formées lors du refroidissement rapide nécessaire à la vitrification, qui est responsable de cette évolution des propriétés vibratoires. Cependant, après vieillissement, la limite théorique thermoélastique n’est toujours pas atteinte et la question du mécanisme dissipatif limitant reste ouverte.
Download or read book Verres m talliques massifs base de titane written by Jinna Mei and published by . This book was released on 2009 with total page 281 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deux verres métalliques massifs base titane, avec la composition nominale Ti40Zr25Ni8Cu9Be18 et Ti41.5Cu37.5Ni7.5Zr2.5Hf5Sn5Sil, qui montrent des variétés structurales différentes (germes/phase amorphe et séparation de phases, respectivement), ont été étudiés. Nos études se concentrent sur les transformations structurales thermiquement induites (relaxation et cristallisation structurales) et leurs effets sur la thermodynamique et la cinétique de la transition vitreuse et la cristallisation aussi bien que la réponse mécanique à la température ambiante. Ainsi que la déformation homogène dans la région du liquide surfondu et les propriétés physiques à basse température. En conséquence, leur enthalpie de relaxation suit les caractéristiques générales admises malgré la nature unique de leurs structures. Le deuxième verre présenté montre une meilleure stabilité thermique bien qu'il présente une plus faible capacité à former la structure vitreuse. Les transformations de phases lors du chauffage ont aussi été étudiées par diffraction de Neutron ainsi que par les modèles JMA et de Starink. Ce dernier a été introduit pour étudier leur cinétique de cristallisation. Les 2 verres montrent de hautes valeurs de résistance à la compression, toutefois avec des contraintes plastiques sensiblement différentes à température ambiante. Leur déformation et comportement uniques à la rupture, dont les changements d'angles de rupture
Download or read book How Glass Changed the World written by Seth C. Rasmussen and published by Springer Science & Business Media. This book was released on 2012-02-23 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glass production is thought to date to ~2500 BC and had found numerous uses by the height of the Roman Empire. Yet the modern view of glass-based chemical apparatus (beakers, flasks, stills, etc.) was quite limited due to a lack of glass durability under rapid temperature changes and chemical attack. This “brief” gives an overview of the history and chemistry of glass technology from its origins in antiquity to its dramatic expansion in the 13th century, concluding with its impact on society in general, particularly its effect on chemical practices.
Download or read book Applied Mineralogy in the Mining Industry written by W. Petruk and published by Elsevier. This book was released on 2000-11-29 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: Techniques of performing applied mineralogy investigations, and applications and capabilities of recently developed instruments for measuring mineral properties are explored in this book intended for practicing applied mineralogists, students in mineralogy and metallurgy, and mineral processing engineers. The benefits of applied mineralogy are presented by using in-depth applied mineralogy studies on base metal ores, gold ores, porphyry copper ores, iron ores and industrial minerals as examples. The chapter on base metal ores includes a discussion on the effects of liberation, particle sizes and surfaces coatings of Pb, Cu, Fe, Ca and So4- on the recoveries of sphalerite, galena and chalcopyrite. The chapter on gold discusses various methods of determining the quantities of gold in different minerals, including 'invisible' gold in pyrite and arsenopyrite, so that a balance of the distribution of gold among the minerals can be calculated. This book also discusses the roles of pyrite, oxygen, moisture and bacterial (thiobacillus ferrooxidans) on reactions that produce acidic drainage from tailings piles, and summarizes currently used and proposed methods of remediation of acidic drainage.
Download or read book Flexoelectricity in Liquid Crystals written by Agnes Buka and published by World Scientific. This book was released on 2013 with total page 299 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book intends to give a state-of-the-art overview of flexoelectricity, a linear physical coupling between mechanical (orientational) deformations and electric polarization, which is specific to systems with orientational order, such as liquid crystals. Chapters written by experts in the field shed light on theoretical as well as experimental aspects of research carried out since the discovery of flexoelectricity. Besides a common macroscopic (continuum) description the microscopic theory of flexoelectricity is also addressed. Electro-optic effects due to or modified by flexoelectricity as well as various (direct and indirect) measurement methods are discussed. Special emphasis is given to the role of flexoelectricity in pattern-forming instabilities. While the main focus of the book lies in flexoelectricity in nematic liquid crystals, peculiarities of other mesophases (bent-core systems, cholesterics, and smectics) are also reviewed. Flexoelectricity has relevance to biological (living) systems and can also offer possibilities for technical applications. The basics of these two interdisciplinary fields are also summarized.
Download or read book Organic Solid State Lasers written by Sébastien Forget and published by Springer. This book was released on 2013-07-03 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic lasers are broadly tunable coherent sources, potentially compact, convenient and manufactured at low-costs. Appeared in the mid 60’s as solid-state alternatives for liquid dye lasers, they recently gained a new dimension after the demonstration of organic semiconductor lasers in the 90's. More recently, new perspectives appeared at the nanoscale, with organic polariton and surface plasmon lasers. After a brief reminder to laser physics, a first chapter exposes what makes organic solid-state organic lasers specific. The laser architectures used in organic lasers are then reviewed, with a state-of-the-art review of the performances of devices with regard to output power, threshold, lifetime, beam quality etc. A survey of the recent trends in the field is given, highlighting the latest developments with a special focus on the challenges remaining for achieving direct electrical pumping of organic semiconductor lasers. A last chapter covers the applications of organic solid-state lasers.
Download or read book ZnO Thin Films written by Paolo Mele and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zinc oxide (ZnO) is an n-type semiconductor with versatile applications such as optical devices in ultraviolet region, piezoelectric transducers, transparent electrode for solar cells and gas sensors. This book "ZnO Thin Films: Properties, Performance and Applications" gives a deep insight in the intriguing science of zinc oxide thin films. It is devoted to cover the most recent advances and reviews the state of the art of ZnO thin films applications involving energy harvesting, microelectronics, magnetic devices, photocatalysis, photovoltaics, optics, thermoelectricity, piezoelectricity, electrochemistry, temperature sensing. It serves as a fundamental information source on the techniques and methodologies involved in zinc oxide thin films growth, characterization, post-deposition plasma treatments and device processing. This book will be invaluable to the experts to consolidate their knowledge and provide insight and inspiration to beginners wishing to learn about zinc oxide thin films.
Download or read book Diffusion in Materials DIMAT 2011 written by Igor Bezverkhyy and published by Trans Tech Publications Ltd. This book was released on 2012-04-12 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: The International Conference on Diffusion in Materials (DIMAT) is the benchmark conference series for diffusion in solids. DIMAT 2011 was organized by the University of Bourgogne in association with CNRS, Dijon (France). The conference showcased new results concerning theoretical tools as well as applied research approaches. Diffusion processes affect all types of materials: nanomaterials, materials for energy, metallurgy, glasses and ceramics, but each requires its own numerical tools. Volume is indexed by Thomson Reuters CPCI-S (WoS). This volume comprises most of the contributions presented at DIMAT 2011: 4 plenary lectures delivered by famous high-level scientists plus 88 contributions in the form of keynote lectures, talks and posters.
Download or read book Laser 50 Years Of Discoveries written by Fabien Bretenaker and published by World Scientific. This book was released on 2014-10-27 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book provides an overview of the principle and applications of lasers enriched with numerous illustrations.Being over fifty years old, lasers continue to amaze us. Their performance characteristics are constantly reaching new limits, and the scope of their applications continues to expand. Yet, it took years of effort by teams of physicists to transform the fundamental notions of Einstein into the first experimental beam of laser light. And history is still going on as fundamental research is now triggered by its remarkable properties.This book addresses every aspects of laser light, from its fundamental principles to its industrial applications, at a level particularly suited for high school teachers, students, and anybody curious about science and technology.
Download or read book Physical Properties of Amorphous Materials written by David Adler and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Institute for Amorphous Studies was founded in 1982 as the international center for the investigation of amorphous mate rials. It has since played an important role in promoting the und er standing of disordered matter in general. An Institute lecture series on "Fundamentals of Amorphous Materials and Devices" was held during 1982-83 with distinguished speakers from universities and industry. These events were free and open to the public ,and were attended by many representatives of the scientific community. The lectures themselves were highly successful inasmuch as they provided not only formal instruction but also an opportunity for vigorous and stimulating debate. That last element could not be captured within the pages of a book I but the lectures concentrated on the latest advances in the field I which is why their essential contents are he re reproduced in collective form. Together they constitute an interdisciplinary status report of the field. The speakers brought many different viewpoints and a variety of back ground experiences io bear on the problems involved I but though language and conventions vary I the essential unity of the concerns is very clear I as indeed are the ultimate benefits of the many-sided approach.
Download or read book Nonlinear Optical Materials written by Jerome V. Moloney and published by Springer Science & Business Media. This book was released on 1998-08-13 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mathematical methods play a significant role in the rapidly growing field of nonlinear optical materials. This volume discusses a number of successful or promising contributions. The overall theme of this volume is twofold: (1) the challenges faced in computing and optimizing nonlinear optical material properties; and (2) the exploitation of these properties in important areas of application. These include the design of optical amplifiers and lasers, as well as novel optical switches. Research topics in this volume include how to exploit the magnetooptic effect, how to work with the nonlinear optical response of materials, how to predict laser-induced breakdown in efficient optical devices, and how to handle electron cloud distortion in femtosecond processes.
Download or read book Food Fray written by Lisa H. WEASEL Ph.D. and published by AMACOM Div American Mgmt Assn. This book was released on 2008-12-10 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: More than ten years ago, the first genetically modified foods took their place on the shelves of American supermarkets. But while American consumers remained blissfully unconcerned with the new products that suddenly filled their kitchens, Europeans were much more wary of these “Frankenfoods.” When famine struck Africa in 2002, several nations refused shipments of genetically modified foods, fueling a controversy that put the issue on the world's political agenda for good. In Food Fray, esteemed molecular biologist Dr. Lisa H. Weasel brings readers into the center of this debate, capturing the real-life experiences of the scientists, farmers, policymakers and grassroots activists on the front lines. Here she combines solid scientific knowledge and a gripping narrative to tell the real story behind the headlines and the hype. Seminal and cutting-edge, Food Fray enlightens and informs and will allow readers to make up their own minds about one of the most important issues facing us today.
Download or read book Modeling Uncertainty in the Earth Sciences written by Jef Caers and published by John Wiley & Sons. This book was released on 2011-05-25 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling Uncertainty in the Earth Sciences highlights the various issues, techniques and practical modeling tools available for modeling the uncertainty of complex Earth systems and the impact that it has on practical situations. The aim of the book is to provide an introductory overview which covers a broad range of tried-and-tested tools. Descriptions of concepts, philosophies, challenges, methodologies and workflows give the reader an understanding of the best way to make decisions under uncertainty for Earth Science problems. The book covers key issues such as: Spatial and time aspect; large complexity and dimensionality; computation power; costs of 'engineering' the Earth; uncertainty in the modeling and decision process. Focusing on reliable and practical methods this book provides an invaluable primer for the complex area of decision making with uncertainty in the Earth Sciences.
Download or read book Clean Energy Nation written by Gerald McNerney and published by AMACOM Div American Mgmt Assn. This book was released on 2012 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: Americans are already feeling the pressures of the current energy situation, and many of us are ready to make a change. Clean Energy Nation is a timely and hopeful look at an issue we can't afford to ignore. --Book Jacket.
