Improved mechanical properties in oxidation resistant AlCrN coatings through Ti addition
(English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Quaternary cubic (c)-(TixCryAl~0.60)1N1 coatings with different x to y ratios have been grown using reactive cathodic arc evaporation. Results show that by adding Ti the high temperature mechanical properties are drastically improved with a retained hardness up to 1100 ºC. The coatings show an age hardening process caused by the formation of hexagonal (h)-AlN and cubic (c)-TiCrN precipitates surrounded by a TiCrAlN host matrix. The improved properties are discussed in terms of kinetics where the addition of Ti delays and suppresses the growth the h-AlN phase. The Ti atoms also generate incoherent crystallites within the h-AlN domains disrupting the hexagonal lattice during the coarsening process. Altogether the result is that the detrimental effects that are normally associated with the hexagonal phase are shifted to higher temperatures.
The oxidation resistance is also investigated with different amount of Ti addition. The addition of Ti promotes the formation of a TiO2 oxide layer over Al2O3 resulting in a lower oxidation resistance. However, by tuning the composition it is possible to generate coatings having both high oxidation resistance and excellent high temperature mechanical properties.
IdentifiersURN: urn:nbn:se:liu:diva-80181OAI: oai:DiVA.org:liu-80181DiVA: diva2:546053