Fundamental study of corrosion-preventive compounds: Part III—soft films

Abstract

Soft film corrosion-preventive compounds (CPC) were studied using ASTM B117 accelerated corrosion testing method and a special test specimen. The tested CPCs included a commercial product and homemade CPCs with a generic formulation containing paraffin wax, petrolatum, corrosion inhibitors and surfactants. Carbon steel substrates coated with CPCs containing corrosion inhibitors and surfactants showed little corrosion after 21 days of exposure in an ASTM B117 chamber. However, the carbon steel substrates coated with CPCs containing no inhibitors or surfactants showed severe corrosion after 7 days of exposure. The effect of CPCs on galvanic corrosion prevention was studied using a special test specimen configuration consisting of a primer-coated AA7075-T6 panel coupled with SS316 fasteners. The galvanic currents between the panel and fastener were measured using a zero-resistance ammeter during exposure of the test specimen in the ASTM B117 chamber. The galvanic attack of the panels coated with different CPCs was evaluated.