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.