Plasma polymerization using a constricted anode plasma source

This paper investigates plasma polymerization of hexamethyl disiloxane (HMDSO) using a constricted anode plasma source (CAPS). The CAPS uses a new electrode configuration i.e. a small anode surrounded by a large cathode, which allows a plasma to be sustained at low pressure of 1×10−3 mbar. Using CAPS, polymerization of HMDSO in the presence of oxygen was carried out, which resulted in the formation of pinhole free glass-like coating on aluminum substrates. The coating was analysed using X-ray photoelectron spectroscopy, which confirmed the presence of the SiOC and the SiOx. Near the coating surface more oxygen was obtained than in the bulk of the coating. With the increase in the deposition temperature, the carbon content in the coating decreased. The corrosion resistance also increased with the increase in deposition temperature. The results establish that the new electrode configuration used in the present investigation can produce good quality coatings by polymerization of a precursor.