Protective SixOyCz coatings on steel prepared by plasma activated chemical vapour deposition

Abstract

The aim of this paper is to analyze the protective character of SixOyCz coatings deposited on steel. Coatings were deposited by r.f. plasma assisted chemical vapour deposition using methyltrimethoxy-silane (MTMOS) as precursor in a gaseous mixture of O2. The process is developed in two stages, first with the substrate at 500°C and in the second stage with the substrate at room temperature. The first stage is made with the mixture of O2 and MTMOS, in the second stage a potential of BIAS in the substrate without varying the mixture of gases is added shrouds of the plasma. Surface chemical and morphological characterization of coatings was carried out by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and corrosion test measurements.The corrosion protective behaviour of the film was determined by potentiodynamics polarization curves with coated probes and without coating, in 5% H2SO4 and NaCl 0.1N solution in nitrogen atmosphere, at room temperature.The new process was successful in producing coatings with good adhesion and the properties are compatible with good corrosion resistance. The deposition process and the film properties are discussed.