Pulsed Thermal Spray (PTS) Aluminum Coatings as Cadmium Replacement for Corrosion Protection of High-Strength Steels

A novel Pulsed Thermal Spray (PTS) system has been developed for depositing aluminum coatings on high-strength steel substrates as a cadmium replacement for corrosion protection. The microstructure of the coatings was investigated by scanning electron microscope, which shows that the coatings are dense with grain size of 100-200 nm. The open-circuit potential of the PTS Al coating is lower than high-strength steel and can provide cathodic sacrificial protection of the steel substrates. The PTS Al coatings have excellent bonding strength (2570 psi) with the steel substrates. Using ASTM B117 and ASTM G 85 cyclic SO₂ salt spray tests, we demonstrated that PTS pure aluminum coatings have superior corrosion resistance when compared with Cd for protecting high -strength steel substrates and satisfies other requirements as a Cd replacement. When combined with epoxy primer top coatings, PTS aluminum coatings show excellent corrosion and scribe resistance. The PTS process is also capable of coating external and internal surfaces as well as non-line-of-sight surfaces.

Keywords: Pulsed Thermal Spray, PTS, cadmium replacement, corrosion protection, high-strength steel, inner diameter coating