Structure–property relations of arc-evaporated Al–Cr–Si–N coatings

✍ Scribed by J. Soldán; J. Neidhardt; B. Sartory; R. Kaindl; R. Čerstvý; P.H. Mayrhofer; R. Tessadri; P. Polcik; M. Lechthaler; C. Mitterer

• Book ID: 104094217
• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 841 KB
• Volume: 202
• Category: Article
• ISSN: 0257-8972
• DOI: 10.1016/j.surfcoat.2007.12.041

✦ Synopsis

The addition of silicon to the widely used aluminum-containing transition metal nitrides is promising for the synthesis of hard and thermally stable films with good oxidation resistance. For that reason, Al-Cr-Si-N coatings were deposited by reactive cathodic arc-evaporation under industrial conditions from Al 70 Cr 30 -x Si x (x = 0, 1, 2, 5 at.%) targets at substrate bias voltages ranging from -40 V to -150 V. The structure of the well adherent coatings was investigated by X-ray diffraction and Raman spectroscopy, which indicated at higher Al/Cr ratio N 1.9 an increased tendency of the metastable face-centered cubic solid solution of AlN in CrN to separate into a cubic-hexagonal phase mixture. At higher bias voltages, this effect is gradually inverted and the single cubic phase can be retained. X-ray photoelectron spectroscopy revealed dominant Si-N bonds suggesting either a substitutional solid solution or a separate Si-N phase. Mechanical properties, i.e. hardness and elastic modulus, measured by indentation together with stress evolution demonstrate the beneficial effect of the conservation of the metastable cubic phase.