WEAR RESISTANT COATINGS DEPOSITED BY PSII AND PIIP FOR USE AS A BARRIER TO MARINE CORROSION

摘要

Plasma source ion implantation (PSII) and Plasma immersion ion processing (PIIP) are non-line-of-sight processes for implanting and coating complex shaped targets without the need for complex fixturing. Previous PSII and PIIP investigations have focused on implanting and coating from inert and hydrocarbon base gases. With the recent development of low melting point organometallics, it is now possible to produce metal base coatings. One such organometallic that has potential for both wear and corrosion resistance is chrome-carbonyl (Cr(CO)_6). The composition of a PIIP deposited coating from Cr(CO)_6 was characterized by x-ray photoelectron spectroscopy. Results indicated that the outer layers of the coating were high in carbon and oxygen content while the inner layers were enriched in Cr with respect to the organometallic stoichiometry. In addition, the coating was adherent and had a high hardness, on the order of 2000 kg/mm~2. The results from corrosion studies on the PIIP Cr-base coating on carbon steel are compared to results from PSII DLC coatings on the same substrate. The breakdown of both coatings was attributed to small pinholes formed during the deposition process. In comparison, implantation (from PSII) was found to produce a uniform surface with increased resistance to corrosion.