Space applicable DOE photovoltaic technology: An update

Photovoltaic development projects applicable to space power are identified. When appropriate, the type of NASA support that would be necessary to implement these technologies for space use is indicated. It is conducted that the relatively small market and divergent operational requirements for space power are mainly responsible for the limited transfer of terrestrial technology to space applications. Information on the factors which control the cost and type of technology is provided. Terrestrial modules using semiconductor materials are investigated

Structure and Properties of the Multicomponent and Nanostructural Coatings on the Sintered Tool Materials

This chapter presents a general characteristic of sintered tool materials, in particular sintered sialons, nitride ceramics, injection-moulded ceramic-metallic tool materials and cemented carbides and a general characteristic of their surface treatment technology and especially chemical vapour deposition (CVD) and physical vapour deposition (PVD) techniques. The results of our investigations in technology foresight methods concerning the development prospects of surface engineering of sintered tool materials are presented. In the next subsection, we discuss the outcomes of multifaceted research carried out with advanced materials engineering methods, including high-resolution transmission electron microscopy, into the structure and properties of multicomponent, graded and multilayer coatings on the investigated tool materials, including the newly developed injection moulded ceramic-metallic tool materials. Special attention was drawn to a one-dimensional structure of the studied PVD and CVD coatings and its impact on the properties of coatings

Investigations on micro-mechanical properties of polycrystalline Ti(C,N) and Zr(C,N) coatings

Micro-mechanical properties of Ti(C,N) and Zr(C,N) coatings deposited by chemical vapor deposition on a WC-Co cemented carbide substrate were examined by micro-compression testing using a nanoindenter equipped with a flat punch. Scanning Electron Microscopy, Focused Ion Beam, Electron Backscattered Diffraction and Finite Element Modeling were combined to analyze the deformation mechanisms of the carbonitride layers at room temperature. The results revealed that Ti(C,N) undergoes a pure intergranular crack propagation and grain decohesion under uniaxial compression; whereas the fracture mode of Zr(C,N) was observed to be inter/transgranular failure with unexpected plastic deformation at room temperature.Peer ReviewedPostprint (author's final draft

Study of CVD Coatings Used for Cutting Tools

Import 26/06/2013Čížek, L. Studium CVD povlaků používaných v oblasti řezných nástrojů ze slinutého karbidu, jejich vlastnosti a aplikační oblasti: VSB – Technická univerzita Ostrava, Fakulta strojní, katedra mechanické technologie, 2013 Bakalářská práce, vedoucí: Doc. Ing. Jitka Podjuklová, CSc. Ve své bakalářské práci se zabývám jedním z typů tenkých povlaků, a to CVD povlaky (Chemical Vapor Deposition), v oblasti řezných nástrojů. Tyto nástroje jsou ve většině případů vyměnitelné břitové destičky ze slinutého karbidu, používané při soustružení a frézování. V úvodu se seznámíme s historií povlakování, dále pak se slinutým karbidem a poté se zaměříme na princip této metody, typy a popis jednotlivých povlaků, jejich vlastnosti a aplikační oblasti. V praktické části jsem porovnával vlastnosti tří vzorků destiček s CVD povlakem, bylo analyzováno složení, tloušťka jednotlivých vrstev, ad-heze povlaku a měřena jeho tvrdost. Na konec byly destičky podrobeny testu trvanlivos-ti při frézování. Nejlépe vyšel vzorek č. 3. Výsledky jsou uvedeny v závěru této práce.Cizek, L. Study of CVD coatings used for cutting tools carbide, properties and application areas: VSB – Technical University of Ostrava, Faculty of Mechanical, Department of Mechanical Technology, Thesis, leader: Doc. Ing. Jitka Podjuklova, CSc. In my thesis I focus on one type of thin coatings, CVD (Chemical Vapor Deposition), in the area of cutting tools. These tools are in most cases inserts from sintere carbide used in turning and milling. In the introduction, we get familiar with history of coating and sintered carbide, then we focus on principle of this method and description of coatings types, their properties and application areas. In the practical part, I compared properties of three samples with CVD. Composition and thickness of each layer, adhesion re-sistance of coating to thermal crakcs were analysed and its hardness was measured. At the end inserts were subjected to the durability test in milling. Description, documenta-tion and results are listed at the end of this work.345 - Katedra mechanické technologievelmi dobř

Method of Fabricating Schottky Barrier solar cell

On a thin substrate of low cost material with at least the top surface of the substrate being electrically conductive is deposited a thin layer of heavily doped n-type polycrystalline germanium, with crystalline sizes in the submicron range. A passivation layer may be deposited on the substrate to prevent migration of impurities into the polycrystalline germanium. The polycrystalline germanium is recrystallized to increase the crystal sizes in the germanium layer to not less than 5 micros to serve as a base layer on which a thin layer of gallium arsenide is vapor epitaxially grown to a selected thickness. A thermally-grown oxide layer of a thickness of several tens of angstroms is formed on the gallium arsenide layer. A metal layer, of not more about 100 angstroms thick, is deposited on the oxide layer, and a grid electrode is deposited to be in electrical contact with the top surface of the metal layer. An antireflection coating may be deposited on the exposed top surface of the metal layer

Solvent free method for intense vaporization of solid molecular and inorganic compounds

New tools have been developed for vaporization of solid precursors to meet the demands of high feed rate for CVD, ALD and other deposition processes

Towards an understanding of nanometric dielectrics

Dielectric studies are described aimed at providing an understanding of the charge storage and transport of an epoxy resin containing TiO2 nanoparticles. Comparative results for conventionally filled composites are given, and the results discussed in terms of the underlying physics. It is shown that nanometric fillers mitigate the interfacial polarization characteristic of conventional materials with a reduction in the internal field accumulations

Design of Comb Crack Resistant Milling Inserts: A Comparison of Stresses, Crack Propagation, and Deformation Behavior between Ti(C,N)/α-Al2O3 and Zr(C,N)/α-Al2O3 CVD Coatings

Investigations on comb crack resistance of milling inserts coated with chemical vapor deposition (CVD) Ti(C,N)/α-Al2O3 and Zr(C,N)/α-Al2O3 showed a distinct wear evolution in both systems. Wear studies revealed that the appearance of comb cracks is connected to the initial CVD cooling crack network. Micropillar compression tests indicated a brittle intergranular fracture mechanism for the Ti(C,N) layer and a transgranular fracture accompanied with signs of plastic deformation for the Zr(C,N) coating. Additionally, for the Zr(C,N) based system, a compressive stress condition in the temperature range of interest (200–600 ◦C) was determined by in-situ synchrotron X-ray diffraction. The set of residual compressive stresses together with the ability of the Zr(C,N) layer to deform plastically are key features that explain the enhanced resistance to comb crack wear of the Zr(C,N) based system in milling of cast iron