Role of hydration layer on rheology of nano alumina suspensions

Technological implication of reduction in viscosity of nanosize ceramic suspensions with environmentally benign and inexpensive additives is not trivial. This presentation will discuss the flow characteristics of concentrated nano-alumina powder suspensions. Unusually high viscosities observed for suspensions of nanoparticles compared to those of micron size powders cannot be explained by current viscosity models. For a given solids content, as the particle size decreases so does the interparticle distance leading to overlapping interparticle forces. Concomitant with the particle size reduction, increase in surface area of the solids requires higher surfactant concentrations for effective steric stabilization. The rheology of nanosize alumina suspensions and its variation with solids content and with saccharide concentration were explored by rheometry. The mechanism of dramatic viscosity reduction by saccharide addition (primarily fructose) is studied by TGA, DSC, and NMR. The interparticle forces between the nanometric alumina particles in water and in fructose solutions were investigated by AFM. The interactions between the nano-alumina particles in water can be explained by the DLVO theory. However, DLVO theory can not adequately describe the interactions between particles for suspensions containing saccharide. The interaction forces (amplitude and range) between nanometric alumina particles decrease with increasing saccharide concentration. Formation of so-called hydration layer on alumina nanoparticles in water was hypothesized for years, but never observed experimentally. The direct visualization of hydration layer over nanosize alumina particles was realized with the fluid cell transmission electron microscopy in situ. The hydration layer over the particle aggregates was observed and it was shown that these hydrated aggregates constitute new particle assemblies which in turn alter the flow behavior of the suspensions. These nanoclusters alter the effective solids content and the viscosity of nanosize alumina suspensions. Our findings elucidate the source of high viscosity observed for nano particle suspensions and are of direct relevance to many industrial sectors including materials, food, cosmetics, pharmaceutical among others employing colloidal slurries with nanosize particles

Enlargement and Integration Action Activity Workshop on Costs, Benefits and Impact Assessment of Smart Grids for Europe and Beyond

Smart Grids are a key component of the European strategy toward a low-carbon energy future. Growing environmental and energy security concerns represent a major driver for the renovation and improvement of existing energy infrastructure. In this context, Enlargement and Integration countries will have to face substantial investments in the coming years to upgrade and modernise their energy networks towards smart power grids. Wind and solar electricity retain the greatest potential to contribute and increase the shares of renewable electricity production; however, current electricity transmission and distribution systems do not generally appear adequate to reliably cope with large-scale penetration of such variable renewables based generating plants (whether centralised or distributed). Significant investments will need to be mobilized. Most energy investments are long life and capital intensive, therefore investment decisions taken now will have an impact for many years. When planning the electricity system of the future, it is necessary to adopt an integrated approach to assess the interrelated physical, environmental, cyber, social, economic and policy challenges where a fair allocation of short term costs and long term benefits among different players is a precondition for reducing uncertainties and incentivize investments. In this context the workshop will discuss how these developments can provide examples and opportunities for E&I countries to build smart grids and will present and discuss approaches and methodologies for cost – benefit analysis that should include all the costs and benefits that smart grid projects can bring to the energy system at large and to society. The workshop will discuss the impacts of smart grids not only in monetary terms, but also through the identification of externalities and social impacts that can result from the implementation of Smart Grid. The workshop will benefit from the on-going experience in Enlargement and Integration Countries on smart grid developments.JRC.F.3-Energy Security, Systems and Marke

Boron modified molybdenum silicide and products

A boron-modified molybdenum silicide material having the composition comprising about 80 to about 90 weight % Mo, about 10 to about 20 weight % Si, and about 0.1 to about 2 weight % B and a multiphase microstructure including Mo.sub.5 Si.sub.3 phase as at least one microstructural component effective to impart good high temperature creep resistance. The boron-modified molybdenum silicide material is fabricated into such products as electrical components, such as resistors and interconnects, that exhibit oxidation resistance to withstand high temperatures in service in air as a result of electrical power dissipation, electrical resistance heating elements that can withstand high temperatures in service in air and other oxygen-bearing atmospheres and can span greater distances than MoSi.sub.2 heating elements due to improved creep resistance, and high temperature structural members and other fabricated components that can withstand high temperatures in service in air or other oxygen-bearing atmospheres while retaining creep resistance associated with Mo.sub.5 Si.sub.3 for structural integrity

Carbon or boron modified titanium silicide

A titanium silicide material based on Ti.sub.5 Si.sub.3 intermetallic compound exhibits substantially improved oxidative stability at elevated temperatures. In particular, carbon is added to a Ti.sub.5 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.6 weight % C) effective to impart substantially improved oxidative stability at elevated temperatures, such as about 1000 Si.sub.3 base material in an amount (e.g. about 0.3 to about 3.3 weight % B) to this same end