Preparation and characterization of Cr-O films grown by low-temperature chemical vapor deposition

摘要

The preparation of chromium oxide films was investigated using the chemical vapor deposition (CVD) process in order to improve the corrosion resistance of 304 stainless steel in a chloride environment. The compounds Cr(CO){sub}6 and Cr(C{sub}7H{sub}5O{sub}2){sub}3 were used as precursors which have low decomposition temperature (below 473 K). The deposition temperatures explored for Cr(CO){sub}6 precursor were from 496 to 753 K and the total pressure were controlled from 0.1 to 1.0 torr. The deposition temperatures for the Cr(C{sub}7H{sub}5O{sub}2){sub}3 precursor were from 673 to 933 K and the pressures were from 50 to 585 torr. Ultra high pure oxygen gas was added into the deposition chamber to help the formation of a specific Cr{sub}xO{sub}y film. Morphological characterization of the films was performed by X-ray diffraction (XRD), scanning (SEM) and transmission (TEM) electron microscopies. SEM and TEM results showed that most of the films have a columnar structure with small agglomerated particles (below 100 nm) on the surface. The films thickness varied from 2 to 8 μm. The XRD results made evident that the films prepared from Cr(C{sub}7H{sub}5O{sub}2){sub}3 precursor consist of CrO and Cr{sub}2O{sub}5, in contrast, the films prepared using Cr(CO){sub}6 precursor consists of Cr{sub}2O{sub}3. The corrosion resistance study of the chromium oxide films is still in progress.