Moulage en sable

Le moulage en sable utilise un matériau réfractaire et qui se présente sous la forme de petits grains ; on peut donc lui donner la forme que l'on veut, et figer cette forme avec un additif. Cela en fait un matériau de choix pour la conception de moules ; cependant, c'est un moule à usage unique, mais que l'on peut fabriquer facilement de manière répétée. Le modèle Généralités Différents types de modèles

Un modèle nature est un modèle en bois ou en résine dont la forme est celle de la pièce. Il peut être coupé en deux ou livré sur plan de joint, si ce "plan" de joint n'est pas plan au sens géométrique du terme ; dans ce cas, le modeleur livre avec son modèle un support matérialisant le plan de joint, dans lequel le modèle ira se loger.
Un modèle en bois, résine, ou alliages métalliques monté sur plaques-modèle est coupé en deux et chaque partie est fixée sur une plaque comportant des dispositifs de positionnement. Ce type de modèle s'utilise

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Nanosized Optoelectronic Devices Based on Photoactivated Proteins

Sandro Carrara, Giovanni De Micheli, Danilo Demarchi, Gianluca Piccinini

Molecular nanoelectronics is attracting much attention, because of the possibility to add functionalities to silicon-based electronics by means of intrinsically nanoscale biological or organic materials. The contact point between active molecules and electrodes must present, besides nanoscale size, a very low resistance. To realize Metal-Molecule-Metal junctions it is, thus, mandatory to be able to control the formation of useful nanometric contacts. The distance between the electrodes has to be of the same size of the molecule being put in between. Nanogaps technology is a perfect fit to fulfill this requirement. In this work, nanogaps between gold electrodes have been used to develop optoelectronic devices based on photoactive proteins. Reaction Centers (RC) and Bacteriorhodopsin (BR) have been inserted in nanogaps by drop casting. Electrical characterizations of the obtained structures were performed. It has been demonstrated that these nanodevices working principle is based on charge separation and photovoltage response. The former is induced by the application of a proper voltage on the RC, while the latter comes from the activation of BR by light of appropriate wavelengths.

Amer Chemical Soc2012

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Towards tailored cement-based materials with ground calcium carbonates

Emmanuel Denarié, Lionel Sofia

Proportioning the dosage of Ground Calcium Carbonates (GCC) in cementitious materials, beyond current normative levels, is one of the most promising ways towards sustainability of mortar and concrete technology. Performance parameters such as the water/binder ratio do not represent the very significant benefits in terms of mechanical performances, of clinker replacement by GCC in mixes with water/cement ratios in the range of that for normal concretes used in construction (0.4 to 0.6). Alternative parameters such as the water/fines ratio proved to be reliable indicator of performances for Ultra High-Performance Fiber Reinforced Concretes. This concept needs to be further extended to normal concretes, on a scientific basis. With this aim in view, mortar mixes with a similar water/cement ratio of 0.5 and progressive replacement of sand by GCC with water/fines ratios as low as 0.2 were studied. The packing density of the cement and GCC was determined by means of wet packing measurements using the mixing power method. The Compressible Interaction Packing Model from Fennis was generalized to multiple polydisperse components and used to predict the packing density of the mixes. The rheology at fresh state of the mixes was put into perspective with the packing density, water film thickness and sand packing factor to define reliable indicators of performances at fresh states. Finally, the compressive strength of the mixes at 1 and 28 days was related to the efficiency coefficient of the GCC used.

2021

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Low-temperature, solution-deposited metal chalcogenide films as highly efficient counter electrodes for sensitized solar cells

Michael Graetzel, Linhua Hu, Feng Liu, Mohammad Khaja Nazeeruddin, Bing Zhang

Transition metal chalcogenide crystalline films FeSe2, Cu1.8S, and CuSe have been deposited from solution by drop casting their dissolved inks onto a conductive substrate, followed by a mild thermal treatment. We demonstrate that the resulting chalcogenide films exhibit an excellent catalytic activity and function as highly efficient counter electrodes (CEs) for dye-and quantum dot-sensitized solar cells (DSCs and QDSCs). In particular, the FeSe2 and CuSe films produced herein with novel morphologies show better catalytic activity than that of the conventional Pt coated CE used in DSCs and Cu2S in QDSCs, respectively. Ensuing devices present an improved photovoltaic performance with maximum values of 9.10% for DSCs and 4.94% for QDSCs, comparable to those based on Pt and Cu2S CEs. The efficient CE materials developed here from such a facile and scalable route offer strong potential for a broader solar cell application that requires low-cost and large-scale production.

Royal Soc Chemistry2015

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Fonderie

La fonderie est l'un des procédés de formage des métaux qui consiste à couler un métal ou un alliage liquide dans un moule pour reproduire, après refroidissement, une pièce donnée (forme intérieure

Sable

thumbnail|right|Dunes de la vallée de la Mort en Californie. vignette|Les charroyeurs de sable Stanislao Pointeau 1861. vignette|La Seine à Port-Marly, tas de sable par Alfred Sisley (1875), Chi

Métallurgie

vignette|Métallurgiste travaillant près des hauts-fourneaux. vignette|Ouvriers de la métallurgie dans les années 1920. La métallurgie est la science des matériaux qui étudie les métaux, leurs élabora

MICRO-301: Manufacturing technologies

This course gives an introduction to production methods and manufacturing technologies used in microengineering. The focus is given on the understanding of physical phenomena underlying the processes, the relation between materials, manufacturing processes and design, as well as economical aspects.

ME-212: Industrial production processes

Application des principales catégories de procédés de production. Modèles physiques élémentaires décrivant le comportement des principaux procédés de production. Compréhension de base des aspects économiques des procédés de production. Méthodologie de sélection des procédés à un niveau agrégé.

ME-413: Introduction to additive manufacturing

The state of the art in the domain of additive production processes (the part is built by material addition without use of a shape tool) will be presented. The main application/benefits/shortcomings of the common additive processes as well as technological and economical issues will be discussed.