Cerium-containing hexamethyldisiloxane coatings for corrosion protection of a laser-based powder bed fusion fabricated AlSi10Mg0.3 alloy

This study investigates the formation and mechanism of action of advanced cerium-containing hexamethyldisiloxane (HMDSO) coatings to improve the corrosion resistance of AlSi10Mg0.3 alloy, fabricated by laser-based powder bed fusion (L-PBF). HMDSO coatings were deposited using an aerosol-assisted atmospheric pressure plasma deposition (APPD) process to protect the metal surface. This study investigated the effect of different cerium concentrations in the aerosol solution on the deposition process. The coatings were characterised using profilometry to determine coating thickness, while light optical microscopy was used for morphology analyses. Fourier transform infrared spectroscopy and transmission electron microscopy provided detailed information about coating formation and microstructure, while corrosion behaviour was assessed through potentiodynamic polarisation (PDP) measurements in 0.1 M NaCl solution and six-weeks salt-spray tests (ASTM B117–23). Results showed that aerosol-assisted APPD enables the deposition of approximately 800 nm thick HMDSO coatings with incorporated CeO2 nanoparticles. Corrosion measurements revealed reduced corrosion current density, indicating improved corrosion resistance. The presence of cerium in the coatings further enhanced this resistance, as the formed CeO₂ nanoparticles acted as diffusion barriers against the corrosive medium. Corrosion testing confirmed that the coating with 10 wt% cerium in the aerosol solution provided the most durable protection. Cerium-containing HMDSO coatings have demonstrated beneficial corrosion protection for L-PBF-fabricated AlSi10Mg0.3 with further possible improvements in studying active protection.