Sökning: "Transition metal nitrides"

Visar resultat 1 - 5 av 39 avhandlingar innehållade orden Transition metal nitrides.

1. 1. Transition Metal Nitrides : Alloy Design and Surface Transport Properties using Ab-initio and Classical Computational Methods

   Författare :Davide G. Sangiovanni; Valeriu Chirita; Lars Hultman; Paul Mayrhofer; Linköpings universitet; []
   Nyckelord :;

   Sammanfattning : Enhanced toughness in brittle ceramic materials, such as transition metal nitrides (TMN), is achieved by optimizing the occupancy of shear-sensitive metallic electronic-states. This is the major result of my theoretical research, aimed to solve an inherent long-standing problem for hard ceramic protective coatings: brittleness. LÄS MER

3. 2. Toughness enhancement in transition metal nitrides

   Författare :Davide Giuseppe Sangiovanni; Valeriu Chirita; Lars Hultman; Sergey Simak; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; cubic; transition metal nitrides; mechanical properties; ab initio; dft; toughness; ductility; electronic structure; Condensed matter physics; Kondenserade materiens fysik;

   Sammanfattning : Toughness enhancements can be induced in cubic-B1 transition metal nitride alloys by an increased occupation of the d-t2g metallic states. In this Licentiate Thesis I use density functional theory to investigate the mechanical properties of TiN and VN and of the ternaries obtained by replacing 50% of Ti and V atoms with M (M = V, Nb, Ta, Mo, and W) to form ordered structures with minimum number of inter-metallic bonds. LÄS MER

4. 3. Atomistic simulation and experimental studies of transition metal systems involving carbon and nitrogen

   Författare :Jiaying Xie; Seshadri Seetharaman; Oleg Ostrovski; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transition metal carbides; Transition metal nitrides; Transition metal carbo-nitrides; Lattice inversion method; Interatomic potential; Atomistic simulation; Metallurgical process engineering; Metallurgisk processteknik;

   Sammanfattning : The present work was initiated to investigate the stability, structural and thermodynamic properties of transition metal carbides, nitrides and carbo-nitrides by atomistic simulations and experimentations. The interatomic pair potentials of Cr-Cr, Mn-Mn, Fe-Fe, C-C, Cr-C, Mn-C, Fe-C, Cr-Fe, Cr-N and Mn-N were inverted by the lattice inversion method and ab initio cohesive energies, and then employed to investigate the properties of Cr-, Mn- and Fe-carbides by atomistic simulations in this work. LÄS MER

5. 4. Reactivity of Transition-Metal Compounds from Electronic Structure

   Författare :Aleksandra Vojvodic; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; magnetic edge states; electronic structure; density-functional theory; growth; surface states and resonances; nitrides; density of states; hydrodesulphurisation; sulphides; steam reforming; transition-metal carbides; Bronsted-Evans Polanyi relation; scaling relations; adsorption; descriptor; reactivity; catalysis;

   Sammanfattning : Transition-metal carbides (TMC's), nitrides, and sulfides belong to the class of materials known as transition-metal compounds (TMX's). Besides having intriguing properties, these materials are relevant for, e.g., growth and catalysis. LÄS MER

7. 5. Thermodynamic investigations of transition metal systems containing coabon and nitrogen

   Författare :Lidong Teng; Seshadri Seetharaman; Tooru Matsumiya; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materials science; thermodynamic activity; galvanic cell technique; transition metal carbides; transition metal nitrides; phase equilibrium; Materialvetenskap; Materials science; Teknisk materialvetenskap;

   Sammanfattning : In view of the important applications of carbides and carbo-nitrides of transition metals in the heat-resistant and hard materials industries, the thermodynamic activities of Cr and Mn in the Cr-C, Fe-Cr-C, Mn-Ni-C and Mn-Ni-C-N systems have been studied in the present work by the use of the galvanic cell technique. CaF2single crystals were used as the solid electrolyte. LÄS MER