Anti-corrosion application of parylene C film for stainless steel fasteners in electroplating industry

Parylene C film was investigated for extending the service life of fasteners used in electroplating. A 10-μm-thick parylene C coating was applied to a 304 stainless steel surface through chemical vapor deposition, and an accelerated lifetime aging test was conducted by immersing the test pieces in a 60 °C copper sulfate solution. Electrochemical analysis was performed to evaluate the penetration of the film by the solution. Based on the experimental data, it was determined that the solution penetrated the metal surface between days 66 and 73, with a conservative estimate of 66 days as the benchmark for film failure. Following the 10° rule in ASTM F1980, this is equivalent to a film life of 2.04 years at room temperature (25 °C). Hence, a parylene C coating can effectively protect a substrate from corrosion in a copper sulfate solution and could extend the lifetime of fasteners used in electroplating.