Influence of Si on the target oxide poisoning during reactive arc evaporation of (Al,Cr)2O3 coatings

Cathodic arc-evaporation is a standard deposition technique to synthesize high quality coatings. However, this technique indicates to be very sensitive when preparing oxide films. It has been shown that the synthesis of (Al0.7Cr0.3)2O3 coatings utilizing Al–Cr composite targets was accompanied by the formation of Al-rich oxide islands formed at the target surface. In order to study a possible influence of dopants on the island formation, powder metallurgically prepared Al0.7Cr0.25Si0.05 targets were investigated on their arcing behaviour in oxygen atmosphere as well as on their suitability to prepare Al–Cr–O coatings. Our investigations show that the addition of small amounts of Si reduces the formation of unfavourable oxide islands, and allows for depositing (Al0.7Cr0.3)2O3 with increased density and preferred crystallographic orientations. The Si content of the synthesized oxide coatings is below the detection limit of elastic recoil detection analysis used resulting in compositions comparable to those synthesized from Si-free Al0.7Cr0.3 targets.