Seed layer stimulated growth of crystalline high Al containing (Al,Cr)2O3 coatings deposited by cathodic arc evaporation

Single layer and dual layer (AlxCr1 − x)2O3 coatings were synthesised by cathodic arc evaporation with different Al contents to study their growth characteristics. It was demonstrated that variations in the Al content, the energy of incident particles and the coating thickness control the crystallinity and the coating texture. Analysis by X-ray diffraction revealed a distinct (110) out of plane orientation after transition from a fine grained nucleation zone to a columnar growth mode. Furthermore, the impact of (AlxCr1 − x)2O3 seed layers with x = 0.25 and 0.5 on the growth of (AlxCr1 − x)2O3 top layers with x = 0.7 and 0.85 was evaluated in detail. According to X-ray diffraction and transmission electron microscopy, the development of the corundum-type crystal structure of the top layer was promoted by local epitaxy if the low Al containing seed layer exhibited a pronounced columnar structure. In this way, crystalline corundum-type coatings with an Al content up to x = 0.85 were obtained.