Low Energy Materials Research Articles

Rotatable magnetron sputtering: downscaling for better understanding

<title/>In coating applications, magnetron sputtering is frequently the technology of choice. In industrial continuous in-line sputtering processes, such as web coating and glass coating, rotatable magnetrons have, to a large extent, supplanted the more classic rectangular sputter magnetrons and constitute the heart of many coating systems with target lengths up to 4 m. However, for many people in the coating business, rotatable magnetrons are quite unknown. When comparing the two types, it looks as if rotatable magnetrons offer significant advantages over planars, as long as the required cylindrical targets are available. Rotabable magnetrons are still a relatively new technology, and have not been fully investigated on a lab scale due to the lack of availability of small systems. Experiments with an in house developed downscaled rotatable magnetron have allowed some of their typical characteristics to be identified. Especially in reactive sputtering, rotatable magnetrons exhibit unusual properties. In this article, it is shown that this peculiar behaviour can be understood as the result of redeposition of previously sputtered material back on the target outside the current discharge plasma zone. This redeposition is, to a large extend, also responsible for the poisoning characteristics as a function of rotation speed of the cathode cylinder. It is also shown that in reactive sputtering, rotatable magnetrons generate two beams of high energy and negatively charged particles which seriously influence the morphology of the growing layer. In between both beams, there is a zone of silence where only sputtered low energy material is deposited and in which fragile materials, such as perovskites can be grown.

Preparation of Cu-Coated Stainless Steel Surfaces for Surperhydrophobic Investigation

Cu-coated stainless steel surfaces containing micro- and nanoscale binary structures having different surface roughness were successfully fabricated by means of a facile one-step electroless plating technology, and the resulting surfaces were modified by the low free energy material HFTHTMS (HFTHTMS = (heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane). The experimental results of wettability exhibit that such unmodified surfaces have a strong adhesive force to water droplets, and their contact angles increase with increasing surface roughness, whereas the modified surfaces by HFTHTMS show the superhydrophobic characteristic with contact angles higher than 150° and sliding angles lower than 5°.

Preparation of Cu-Coated Stainless Steel Surfaces for Superhydrophobic Investigation

Cu-coated stainless steel surfaces containing micro- and nanoscale binary structures with different surface roughness were successfully fabricated by means of a facile one-step electroless plating technology. The resulting surfaces were modified by the low free energy material HFTHTMS (HFTHTMS = (heptadecafluoro-1,1,2,2-tetrahydrodecyl) trimethoxysilane). The experimental results of wettability exhibit that such unmodified surfaces have a strong adhesive force to water droplets, and their contact angles increase with increasing surface roughness, whereas the modified surfaces by HFTHTMS show the superhydrophobic characteristic with contact angles higher than 150° and sliding angles lower than 5°.

Design of psyllium–PVA–acrylic acid based novel hydrogels for use in antibiotic drug delivery

In order to exploit the potential of gel forming medicinally important polysaccharide, we have developed psyllium based hydrogels through graft copolymerization. The optimum conditions for the synthesis of psyllium-poly(vinyl alcohol) (PVA)-poly(acrylic acid) blended hydrogels have been evaluated and their characterization has been carried out by SEMs, FTIR and swelling studies. The optimum conditions for the synthesis of hydrogels have been obtained as 1% (v/v) acrylic acid, 2% (w/v) PVA and 1g of psyllium. The use of very small amount of these petroleum products has developed the low energy, cost effective, biodegradable and biocompatible material for potential biomedical applications. It is the novelty of the present finding. The release of model antibiotic drug tetracycline HCl from the hydrogels has been observed more in pH 2.2 buffer hence these hydrogels are suitable for peptic ulcer caused by Helicobacter pylori. At the same time psyllium has also been reported to cure the ulcerative colitis. Hence, the present drug delivery system will have double potential to cure ulcer. The values of the diffusion exponent for the release of drug have been obtained as (0.774, 0.576 and 0.858) and gel characteristic constant have been (8.884x10(-3), 24.149x10(-3) and 3.989x10(-3)) respectively in pH 2.2 buffer, 7.4 buffer and distilled water. The release of the drug from the hydrogels occurred through non-Fickian diffusion mechanism.

Ultrasound-assisted production of biodiesel fuel from vegetable oils in a small scale circulation process

Biodiesel production from canola oil with methanol was performed in the presence of a base-catalyst by a circulation process at room temperature. In this process, the transesterification was accelerated by ultrasonic irradiation of low frequency (20 kHz) with an input capacity of 1 kW. The influences of various parameters on the transesterification reaction, including the amount of catalyst, the molar ratio of methanol to oil and the reaction time, were investigated. The objective of this work was to produce biodiesel satisfying the biodiesel-fuel standards of low energy consumption and material savings. The optimal conditions were: methanol/oil molar ratio of 5:1 and 0.7 wt.% catalyst in oil. Under these conditions, the conversion of triglycerides to fatty acid methyl esters was greater than 99% within the reaction time of 50 min. Crude biodiesel was purified by washing with tap water and drying at 70 degrees C under reduced pressure.

Direct Growth of Hydroxy Cupric Phosphate Heptahydrate Monocrystal with Honeycomb-Like Porous Structures on Copper Surface Mimicking Lotus Leaf

Superhydrophobic surfaces were prepared on copper foils via a facile assistant surface oxidation technology and subsequent chemical modification with low free energy materials. The three-dimensional (3D) honeycomb-like porous structures made up of nanoslices of hydroxy cupric phosphate heptahydrate (Cu8(PO3OH)2(PO4)4·7H2O) single crystals were constructed by immersing copper foil in an aqueous solution of phosphoric acid and hydrogen peroxide. The pore size of the 3D structure ranges from hundreds of nanometers to two micrometers, and the thickness of the two-dimensional (2D) nanoslices is about 50−100 nm. The wettability of the porous surfaces was transformed from superhydrophilic to superhydrophobic by chemical modification with octadecanethiol (ODT) or 1H,1H,2H,2H-perfluorodecyltriethoxysilane (PDES). It was found that the 3D porous structures of the surfaces helped to amplify the wettability. The resulting static contact angles (CAs) for water were larger than 160° on both of the modified surfaces. Co...

Preparation of a 2024Al-Based Super-Hydrophobic Surface

A super-hydrophobic 2024Al surface with micro- and nano-scale hierarchical crater-like structure has been prepared by constructing the surface and modifying the textured surface with low energy material of HFTHTMS (HFTHTMS = (heptadecafluoro-1,1,2,2-tetrahydrodecyl)trime thoxysilane). The textured surface was characterized by scan electron microscope (SEM) and x-ray photoelectron spectrum (XPS). The SEM image shows the crater-like surface with micro- and nano-scale hierarchical microstructures. The textured surface modified with HFTHTMS has super-hydrophobicity with a contact angle of 162° and the sliding angle of 3°.

Flue gas desulfurization gypsum: Study of basic mechanical, hydric and thermal properties

Abstract Flue gas desulfurization (FGD) gypsum is a waste material produced in desulfurization of flue gases in power stations and heating plants in high amounts. However, the industrial use of FGD gypsum is insufficient considering the amount of its production. Nowadays, it is mostly used for the production of gypsum plasterboards only, and the rest is deposited at waste disposal sites. Calcined gypsum as a low-energy material can be produced with advantage from the waste FGD gypsum by its dehydration at the temperatures of 110–150 °C. The solid structure of calcined gypsum can then be created by reverse hydration. Due to the very low price and large availability of FGD gypsum, the material has a good potential for applications in building structures, possibly also as a material of load-bearing structures. One of the reasons for the neglect of the material by building industry is the almost complete lack of knowledge of its properties. In this paper, the measurements of basic mechanical, thermal and hydric parameters, namely compressive strength, bending strength, thermal resistance, frost resistance, moisture diffusivity, water vapor diffusion coefficient, sorption isotherms, water retention curve, thermal conductivity, volumetric heat capacity, and linear thermal expansion coefficient, of hardened flue gas desulfurization gypsum are presented.

The possibility of recycling flue dust of the ferrochromium productions in Kazakhstan

PurposeThis paper aims to describe a solution for cyclonic flue dust recycling based on the example of ferrochromium producers in Kazakhstan. It includes environmental improvement, which can be assessed in detail based on LCA after the development of a feasibility study of such a proposal.Design/methodology/approachThree pyrometallurgical recycling approaches should be achieved. The first approach is reduction smelting of fine waste in a direct current arc furnace without preliminary agglomeration. The second is reduction smelting of agglomerated waste in a submerged arc furnace, and the third is processing of agglomerated waste with liquid cast iron. The last approach facilitates the reactions of metal oxide reduction by carbon and silicon from the iron with a corresponding decrease in energy and auxiliary material consumption.FindingsValuable material can be produced from ferrochromium dust waste using environmentally friendly technology, including electric furnaces that can operate in SAF regimes and a simple plasma high‐power DC reactor operating under a neutral or reducing atmosphere. Finally, the investigation of waste recycling has developed a novel approach that facilitates metal oxide reduction and provides low energy and auxiliary materials consumption.Practical implicationsResearch into the treatment of flue dust generated in the ferrochromium industry is needed to solve environmental problems not only in Kazakhstan but also in all ferrochromium plants in the world.Originality/valueThe three proposed pyrometallurgical recycling approaches should be achieved on a large scale.

レーザープラズマ粒子加速器開発の最近の進展 1.歴史と今後の展開

Plasma is an attractive medium for the advanced accelerator. When combined with the ultra-intense lasers, it makes the acceleration field one thousand times the field of the current microwave accelerators or the size one thousandth the size. The fields, which require now the particle accelerator, are not only the high energy physics, but also the medical, industrial and low energy material fields. In these 10 years, the laser accelerator research has advanced the electron gain of from 22 MeV to 200 MeV. Recently, it has produced 200 MeV electrons from a 2 mm-long plasma. This corresponds to 100 GV/m. On the other hand, a glass capillary has this year succeeded in making the plasma length, the acceleration length, from 2 mm to 10 mm. Mono-energetic peaks were also found. These will be the breakthrough to the second generation of the advanced accelerator development.This review introduces these topics as well as the development of the ion acceleration studies.

Multifunctional nanocomposite transparent UV-blocking films sythesized by sol-gel process for optical, automotive and aeronautic applications

AbstractDevelopment of UV blocking thin films with effective cut-off features with steep edges and high transmission in the visible and IR region have been developed. The unique optical, mechanical and chemical properties of silica and ceria nanocomposites with surface functional groups making them most promising candidate for applications in opto-electronic, automotive, and aeronautic industries. On the other hand, highly hydro and oleophobic films are being actively considered in optical, automotive and aeronautic industries to increase adhesion and scratch, abrasion resistance properties. In order to fill the gap, and fulfill the requirements to meet both ends, it could be proved that morphological changes in the nanometer range influences the water contact angles and their hystersis of low energy materials. Nanocomposite films of SiO2 and CeO2 with surface functionalisation with decafluorooctly-triethoxy silane itself forms nano-hemispheres (similar to lotus leaf) at and above 100°C favoring an increase in water contact angle from 122° (25°C) to 145°(400°C). The structural, optical, and hydrophobic properties have been examined by employing X-ray diffraction, UV-visible spectroscopy, contact angle techniques, respectively. The cut-off behavior of the deposited and annealed nanocomposite thin films have been tuned by varying different amounts of CeO2 in SiO2.

Surface diagnostics for scale analysis

Stainless steel, polymethylmethacrylate and polytetrafluoroethylene coupons were analysed for surface topographical and adhesion force characteristics using tapping mode atomic force microscopy and force-distance microscopy techniques. The two polymer materials were surface modified by polishing with silicon carbide papers of known grade. The struvite scaling rate was determined for each coupon and related to the data gained from the surface analysis. The scaling rate correlated well with adhesion force measurements indicating that lower energy materials scale at a lower rate. The techniques outlined in the paper provide a method for the rapid screening of materials in potential scaling applications.

Laser Particle Accelerator

Plasma is an attractive medium for the advanced accelerator. When combined with an ultra-intense laser, it makes an acceleration field one thousand times greater than that produced by current microwave accelerators. The major fields, which now require the particle accelerator, are not high energy physics, but the medical, industrial and low energy material fields. Over the last ten years, laser accelerator research has advanced the electron gain from 22 MeV to 200 MeV. Recently, use of a glass capillary has succeeded in increasing the plasma length, the acceleration length, from 2 mm to 10 mm. This will be a breakthrough in the development of the second generation advanced accelerator.

Study on the flotation behaviour of low energy materials at low surface tensions

Surface tension is one of the most important factors in a flotation process, normally being understood to mean surface tension at the pulp surface. In most cases this is enough, but when we try to process materials which have low surface energies, we also have to take into account the surface tension between the air bubbles and the liquid (water) in the flotation cell. This paper reports preliminary study results on this subject.

Microwave ignited combustion synthesis of aluminium nitride

Aluminum nitride, AlN, is a ceramic that has many attractive properties for electronics and refractory applications [1]. These include its high thermal conductivity, typically > 200 W m−1 K−1, low thermal expansion coefficient and high electrical resistivity combined with its ability to be pressureless sintered using additives to theoretical density. AlN powders have also been used as fillers for polymer and glass compounds to enhance the heat transfer characteristics for electronicpackaging applications [1]. Recently, the use of AlN whiskers in high-density substrates and functional films has also attracted interest [2]. AlN can be synthesized using a variety of methods [3], however two main processes have been in industrial operation for some time, the carbothermal reduction of aluminum oxide and the direct nitridation of aluminum. The former consists of heating a mix of alumina and carbon powders to above 1100 ◦C in nitrogen. Unreacted carbon is removed by controlled oxidation at ∼650 ◦C in dry air while a second heat treatment at ≥1400 ◦C in vacuum reduces oxygen pickup and stabilizes the powder. Although this method has the advantages of readily available raw materials and the production of powders that are homogeneously sized and suffer low levels of agglomeration, avoiding carbon and oxygen impurities is difficult [1]. The second process also allows large quantities of powders to be produced with relatively low energy and raw materials’ costs. Being highly exothermic, once the reaction starts it is able to proceed without any additional supply of external heat. However, it is difficult to produce fine, fully nitrided powders because during the reaction the Al powder can form large aggregates due to its melting point (660 ◦C) being lower than the nitridation temperature (≥800 ◦C) [4]. In addition, AlN formation occurs first on the surface of the Al particles inhibiting the diffusion of the nitrogen to the unreacted metal. Extended reaction times are therefore required to allow adequate diffusion while intermittent grinding steps are generally necessary to break the agglomerates and expose fresh surfaces of unreacted Al [5]. Microwaves are electromagnetic radiation in the approximate frequency range 0.3 to 300 GHz. It is now well known that they usually generate an inverse

Energy Tax and Choice of House Construction Techniques in India

Energy conservation is an important issue in building design. Therefore, it is logical to apply the principle of energy costing to building projects and to look for ways to minimize the total energy consumed during the lifetime of a building. Even though the total quantity of energy consumed during the lifetime of a building may be many times more than that consumed during its construction, there are a number of reasons why the energy use in the construction process and, in particular, in the building materials used should be treated as a matter of importance. This paper compares the energy costs in a building constructed using alternative construction techniques. We evaluate energy consumption and resource requirements to construct a representative room of size 3.5 m x 3.5 m x 3.14 m by alternative techniques of construction using an optimization framework. It is generally observed that despite the availability of low energy technologies of construction, they are not adopted. The present paper develops an energy tax system that would induce the use of low-energy building materials and techniques. Finally, the paper concludes with policy recommendations that are essential if energy consumption in building construction is to be minimized.

New technology and innovation at Greenwich Millennium Village

Greenwich Millennium Village next to the Millennium Dome in London is a showcase for innovations in sustainable and efficient construction. The £250 million development of nearly 1400 homes and commercial units features its own web site, a combined heat and power plant, modular bathrooms and plant rooms, water saving devices and low embodied energy materials. It is being procured over a five-year programme through sophisticated partnering arrangements and the first residents move in later this year. This paper describes the technical aspects of the innovations introduced on the project.

Energy deposition calculations in dose measurements of 0.2–3.0 MeV electrons

Abstract In this paper emphasis is laid upon the energy deposition calculations of 0.3–0.6 MeV low-energy electrons in multilayer media. In addition the energy depositions of 0.2–3.0 MeV electrons in some materials have been calculated by the bipartition model of electron transport. The calculation results are in agreement with some experimental data. The energy deposition values of 0.3–0.6 MeV electrons have been fitted into an approximate calculation formula which can be used for dose measurements and calculations of low-energy electron beam radiation curing and film material radiation processing.

Influence of the interfacial free energy crystal/heat transfer surface on the induction period during fouling

The accumulation of unwanted crystalline deposits (fouling) reduces the efficiency of heat exchangers. In order to adjust the operating conditions with respect to fouling mitigation a model for the description of the entire fouling process has to be established. The main disadvantage of known models is the lack of a description of the induction period which is influenced by the nucleation rate and the adhesive strength between crystals and heat transfer surfaces. The deposition and removal process depends on the interfacial free energy crystal/heat transfer surface. For many industrial applications the only possibility to influence the interfacial free energy is to modify the surface energy characteristics of the heat transfer surface, i.e. its surface free energy. Based on the experimental investigation of the surface energy of several metallic and low energy materials their fouling performance when exposed to a liquid flow of a calcium sulphate solution was evaluated. The deployment of new surface materials such as DLC (diamond like carbon) coatings proved to be a strategy to increase the induction period. Influence de l'énergie libre interfaciale cristal / surface de transfert thermique sur la période d'induction de l'encrassement. La formation de couches cristallines (encrassement) diminue l'efficacité des échangeurs. Afin de fonctionner dans de conditions telles que la formation de couches cristallines soit réduite, il est tout d'abord nécessaire de développer un modèle de calcul de toutes les étapes du processus d'encrassement. L'inconvénient des modèles de calcul connus réside dans le fait qu'ils ne prennent pas en considération la phase d'induction. Cette phase importante dépend de la fréquence de formation des germes et des forces d'adhésion entre la couche cristalline et la surface de l'échangeur. Les deux mécanismes de dépôt et d'érosion dépendent de l'énergie interfaciale entre la couche cristalline et la surface de l'échangeur. Dans de nombreuses applications industrielles, la seule possibilité pour agir sur cette énergie interfaciale consiste à modifier les caractéristiques énergétiques de la surface de l'échangeur, c'est-à-dire son énergie de surface. En nous appuyant sur des études expérimentales concernant l'énergie de surface, nous avons analysé le comportement de la surface de l'échangeur lors d'une expérience d'encrassement avec une solution aqueuse de CaSO 4 . L'utilisation de nouveaux matériaux de surface, tels que le DLC ( diamond-like carbon ), permet de prolonger la phase d'induction.

Mechanism of twinning-induced grain boundary engineering in low stacking-fault energy materials

Abstract The current status of “grain boundary engineering” is overviewed, i.e. the deliberate manipulation of grain boundary crystallography in polycrystals in order to produce a material containing grain boundaries which have superior properties compared to average boundaries. A particular focus of attention is annealing twinning in low stacking-fault energy (SFE) materials as a means to achieve this aim, since the role of such twinning in improving the grain boundary network has not hitherto been satisfactorily explained. The twinning is discussed from the viewpoint of strain retention, imposition of crystallographic constraints at grain junctions, “relative specialness” rather than “absolute specialness” and proposal of a new “Σ3 regeneration model” to explain how twins can enhance the Σ3 boundary fraction in the network.