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MM: Fachverband Metall- und Materialphysik

MM 46: Interfaces

MM 46.6: Vortrag

Donnerstag, 28. Februar 2008, 17:45–18:00, H 0111

Ab-initio investigation of chromium carbide - diamond interfaces — Andreas Böhner, •Rebecca Janisch, and Alexander Hartmaier — Friedrich-Alexander-University Erlangen-Nürnberg, Department of Materials Science and Engineering, Institute of General Materials Properties

Superhard carbon coatings, e.g. diamond like carbon on ductile tool steels, promise to feature exceptional resistance to frictional wear and corrosion. Therefore, the development of such carbon coatings is an active field of materials research. A crucial task is to optimize the adhesion between the carbon coating and the subjacent alloy.

To this end we perform a case study of the interface between diamond and chromium carbides of different stoichiometry. We use ab - initio density functional calculations employing plane waves and pseudopotentials. The first step is to study bulk properties - such as equilibrium lattice constant, bulk modulus, and details of the chemical bonding - of different chromium carbides. We then select certain phases for constructing supercells to model the CrC_x diamond interface. After relaxing macroscopic and microscopic degrees of freedom, these interfaces are characterized by calculations of the work of separation and investigation of the electronic structure at the boundary. The influence of superimposed stresses and strain on the results is discussed. The results show a systematic dependence of the characteristic quantities on the C concentration in the carbide and can explain different experimental observations.