TiAlN based wear resistant coatings modified by molybdenum addition

TiAlN based coatings have been deposited by reactive vacuum arc evaporation combined with co-deposition of molybdenum from planar magnetron source. Obtained quasi-multilayer TiAlN/(TiAl)1−xMoxN structure was affected by the specific deposition system geometry. An average molybdenum content was up to 8 at.%. The molybdenum addition resulted in a significant improvement of tribological properties manifesting itself in lowering of friction coefficient vs steel from 0.8 down to 0.5 and wear rate below 10−15 m3/Nm. Other mechanical properties like hardness and adhesion remained unaffected or slightly improved. Observed change of tribological response for studied coatings was interpreted as being caused by beneficial contribution of lubricating molybdenum oxides generated in the tribo-contact during friction process. Molybdenum addition also affected corrosion resistance. It resulted in an improved resistance to pitting corrosion accompanied by increase of corrosion potential for coatings tested by the potentiodynamic method in 0.5 M NaCl solution.