Sökning: "carbide cluster"

Visar resultat 1 - 5 av 15 avhandlingar innehållade orden carbide cluster.

1. 1. Atomic scale modeling of ordering phenomena

   Författare :Mattias Ångqvist; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; tungsten carbide; alloys; ordering phenomena; zeolites; inorganic clathrates; Cluster expansion; Monte Carlo;

   Sammanfattning : Ordering phenomena in materials often have a crucial impact on materials properties. They are governed by the competition between entropy and energy. Accordingly simulating these aspects requires the construction of models that enable a computationally efficient exploration of the relevant configuration space. LÄS MER

3. 2. Influence of microstructure on fatigue and ductility properties of tool steels

   Författare :Mats Randelius; Rolf Sandström; Jens Bergström; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Tool steels; fatigue; ductility; carbides; carbide cluster; inclusion; size distribution; modelling; FEM; Metallurgical process engineering; Metallurgisk processteknik;

   Sammanfattning : Fatigue and ductility properties in various tool steels, produced by powder metallurgy, spray forming or conventionally ingot casting, have been analysed experimentally and successfully compared to developed models. The models are able to predict the fatigue limit and cause for fatigue fracture, and strain- and stress-development until fracture during the ductile fracture process respectively. LÄS MER

4. 3. Silicon-Carbide-Based High-Voltage Submodules for HVDC Voltage-Source Converters

   Författare :Keijo Jacobs; Hans-Peter Nee; Staffan Norrga; Marc Hiller; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Silicon carbide; HVDC converters; voltage source converters; modular multilevel converters; submodule topologies; metal-oxide-semiconductor field-effect transistor MOSFET ; insulated-gate bipolar-transistor IGBT ; power semiconductor devices; high-voltage; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : In order to transition to renewable energy sources and simultaneously meet the increasing demand for electrical energy, highly flexible and efficient grids are required. High-voltage direct-current (HVDC) transmission and grids are foreseen to be a vital part of the future electricity grid. LÄS MER

5. 4. Contacts on Silicon Carbide by Use of Nickel and Tantalum ---Preparation and Characterisation

   Författare :Yu Cao; Chalmers tekniska högskola; []
   Nyckelord :Keywords: Silicon Carbide; Metal Contact; Thin Films; Preferential Etching; Interfacial Reaction; effect; Nickel; Tantalum; #955; Depth Profile; I-V Characteristics.;

   Sammanfattning : Silicon carbide (SiC) is one of the attractive semiconductors due to its good electrical, thermal and mechanical properties. It is a promising material for high temperature, high power and high frequency application. Reliable electrodes are always necessary to utilise SiC for electronic devices. LÄS MER

7. 5. Disordered Icosahedral Boron-Rich Solids : A Theoretical Study of Thermodynamic Stability and Properties

   Författare :Annop Ektarawong; Björn Alling; Michael Widom; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Icosahedral boron-rich solids; Boron carbide; Configurational disorder; First-principles calculations; Thermodynamic stability; Superatom-special quasirandom structure;

   Sammanfattning : This thesis is a theoretical study of configurational disorder in icosahedral boron-rich solids, in particular boron carbide, including also the development of a methodological framework for treating configurational disorder in such materials, namely superatom-special quasirandom structure (SA-SQS). In terms of its practical implementations, the SA-SQS method is demonstrated to be capable of efficiently modeling configurational disorder in icosahedral boron-rich solids, whiles the thermodynamic stability as well as the properties of the configurationally disordered icosahedral boron-rich solids, modeled from the SA-SQS method, can be directly investigated, using the density functional theory (DFT). LÄS MER