Thermisch gespritzte Quasikristall-Verbundschichten für Anwendungen in der Gleitlagertechnik

Compared to other materials alloyed from the same components quasicrystalline phases offer outstanding properties: High thermal stability in mechanical behaviour combined with special thermal and electrical conductivity as well as excellent tribological performance. High hardness is accompanied by heavy brittleness - an undesired property when looking for possible applications like for example anti-adhesive, friction reduced surfaces. A reduction of brittleness can be achieved by embedding quasicrystalline phases into a more ductile material to form a metal-matrix-composite material keeping some quasicrystalline properties. For thermal spraying blended, agglomerated, chemical encased or attrition-milled powders as well as cored wires were sprayed to form such metal-matrix-composite coatings. The investigations included spray trials using material-input prepared by the methods described. These different inputs have been processed in changing compositions each. Spray trials have been processed by following techniques: Arc-Wire-Spraying, High-Velocity-Oxy-Fuel-Spraying, Atmospheric Plasma-Spraying and Wire-Flame- Spraying. Investigations were focused on structural and metallurgical analysis for proving the existence of quasicrystal contents as well as determining adherence and embedding behaviour of the matrix-phase. By Vickers indentation mechanical property analysis was carried out to verify ductility-improvements due to the composite structure. Friction tests were centred onto the evaluation of the sliding-wear-behaviour in respect of interdependencies to the content of quasicrystalline phases.