Dynamic PACVD coating of strip metal with silicon oxide, titanium oxide and amorphous carbon films

Abstract

With the Strip Hollow Cathode (SHC) process a new plasma-assisted chemical vapor deposition (PACVD) process was introduced, which was shown to meet the requirements of dynamic steel strip coating with plasma polymer films from several monomers, utilizing the hollow cathode effect. The operating pressure is in the upper fine vacuum range; the SHC process therefore does not require an extensive vacuum environment. Now, this process has been applied to the deposition of silicon oxide, titanium oxide and amorphous carbon films.The films were deposited onto steel and other conducting sheet substrates, even on coil coated steel strip with a polymer film thickness of at least 50 μm. All films show a dense, pinhole-free structure and are highly uniform in film thickness. The hardness of amorphous carbon and silicon oxide polymer films exhibited values of 19 and 3 GPa, respectively, which is well suited for many scratch protection applications. Additionally, measurements of dielectric breakdown strength yield values higher than 10 MV/cm for both 300 nm and 600 nm thick silicon oxide films. Ellipsometric measurements yield a refraction index of 1.47 (550 nm) in the case of silicon oxide. Color and tribological properties such as hardness, Young's modulus, and scratch resistivity have been evaluated.