Production and Use of Sustainable C2-C4 Alcohols – An Industrial Perspective

In the recent past, society has become increasingly aware of the environmental impact of political and corporate action. Hence, several industrial sectors are currently undergoing a transition to more sustainable products and processes. Sustainable production processes for C2-C4 alcohols can help to decrease the environmental impacts of large downstream markets such as fuels and polymers. However, a reliable and consistent framework is needed for companies to further develop and commercialize these processes. Furthermore, standardized procedures for determining the sustainability of a process are essential in evaluating the environmental benefits.     

Structural,mechanical and electrical-contact properties of nanocrystalline-NbC/amorphous-C coatings deposited by magnetron sputtering

Niobium-carbide nanocomposite coatings with a carbon content varying from 43 to 64 at.% were deposited by dual DC magnetron sputtering. X-ray diffraction, x-ray photoelectron spectroscopy and electron microscopy showed that all coatings consisted of nanometer sized NbC grains embedded in a matrix of amorphous carbon. Mechanical properties and electrical resistivity showed a strong dependency on the amount of amorphous carbon (a-C) and NbC grain size in the coating. The highest hardness (23 GPa), elastic modulus (295 GPa) and the lowest resistivity (260 μΩ cm) were measured for the coating with about 15% of a-C phase. Contact resistance measurements using a crossed cylinder set-up showed lowest contact resistance for the coating containing 33% a-C (140 μΩ at a contact force of 100 N), which is comparable to a Ag reference (45 μΩ at a contact force of 100 N). Comparison with TiC-based nanocomposites studied under similar conditions showed that the NbC system has less tendency to form a-C and that lowest contact resistance is obtained at comparable amounts of a-C phase in both material systems (33% for NbC compared to 35% for TiC). With these good electrical contact properties, the NbC nanocomposites can be considered as a potential material for electrical contact applications.     

Mechanisms and Kinetics of Liquid Silicon Oxidation During Industrial Refining

During oxidative ladle refining (OLR) of silicon, the metal surface is partly oxidized, resulting in the formation of a condensed silica fume (SiO₂). This fugitive emission of silica represents a potential health hazard to the workers in the silicon and ferrosilicon industry. In the current work, industrial measurement campaigns aimed at recording the fume generation during OLR were performed at the Elkem Salten plant in Norway. The measured amounts of silica produced were 2.5–5.1?kg/h, depending on the gas flow rate in the refining process. The rate of silica production correlates with the total flow rate and amount of air in the purge gas, and increases as the flow rate increases. The results of this work suggest that fume generation during OLR primarily results from oxidation of the exposed metal surface, with oxygen transport from the surrounding atmosphere to the metal surface being the limiting factor. Other identified mechanisms of SiO₂ formation were splashing of the metal and/or oxidation of SiO gas carried with the refining purge gas.     

德国中小城镇在国土开发中扮演的重要角色

与大多数欧洲城市相比,德国的城镇体系属于均衡发展的典范。地区的高度自治、联邦体制以及强有力的州政府使德国在两千多年的城市发展历程中,逐渐形成了大中小城市遍布全国的空间形态。这些城市都具有相似的生活质量、便捷的交通和便利的服务。基于对中小城镇的概括定义,本文将首先简要介绍城市均衡发展的历史渊源及小城镇在德国的重要作用,并举例分析一些进行中的都市化过程,随后将选取纽伦堡城市区域作为中小城镇的成功案例重点介绍,最后简要说明支持城镇发展的联邦政策规划。     

Polycrystalline silicon films on glass grown by amorphous-liquid-crystalline transition at temperatures below 330 °C

An approach to deposit polycrystalline silicon layers on amorphous substrates is presented. It is shown that metastable amorphous silicon can be transformed into its more stable microcrystalline structure at a temperature below 330 °C via an intermediate liquid solution stage. In particular, the interaction of liquid indium nanodroplets in contact with amorphous silicon is shown to lead to the formation of circular polycrystalline domains. Crystallinity of these domains is analyzed by micro-Raman spectroscopy. The droplet size necessary for the onset of crystallization is related to the temperature of the film. Full coverage of the substrate with microcrystalline silicon has been obtained at 320 °C within less than one hour. These films might act as seeding layers for further enlargement by steady-state liquid phase epitaxy.