Abstract
Al2O3 coatings deposited by chemical vapor deposition (CVD) at temperatures T ˃ 1000 °C are commonly used for wear and oxidation protection in manufacturing processes. Physical vapor deposition (PVD) gained also great interest to synthesize crystalline Al2O3 at lower temperatures by modification using Cr. High Speed PVD has the potential to synthesize thick crystalline (Al,Cr)2O3 coatings. However, previous studies showed that increasing adhesion strength is necessary for corresponding applications. This study evaluated various interlayer systems to enhance the adhesion strength between (Al,Cr)2O3 functional layer and steel X40CrMoV5-1. AlCrN interlayers of varying thicknesses were deposited, as well as two graded AlCrNg interlayers at different bias voltages. Afterwards, AlCrN/(Al,Cr)2O3 coatings were produced. Hereby, the functional layer thickness is varied. The AlCrNg/(Al,Cr)2O3 compounds show no spallation at the edge of Rockwell imprints and scratches at higher normal forces. The thermal stability of the coatings was investigated by annealing in vacuum at T = 1000 °C and T = 1200 °C. Moreover, no diffusion processes leading to chemical and structural changes was obtained after annealing. Therefore, thick (Al,Cr)2O3 coatings, s ≈ 30 μm, with a graded AlCrNg interlayer provide high potential for protecting hot-work steel against thermal loads up to T = 1200 °C.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
