Corrosion and erosion-corrosion of electrodeposited Ni-P/B4C composites

The present paper reports on electrodeposition, characterisation, corrosion, and erosion corrosion of Ni-P and Ni-P/B-4 C layers on a brass substrate. Alloys with 5%P and 8 vol.-% micrometric B4C were prepared from a lactate bath at pH 4 containing H3PO3. The following deposit properties were measured and related to corrosion behaviour: composition (EDS, XPS), crystalline structure (XRD), morphology; (inplane and cross-sectional SEM). and mechanical properties. The immersion and anodic behaviour of pure matrix and composite samples was studied in slightly acidic. aerated chloride solutions. The presence of B4C particles is correlated with higher crystallinity of the matrix at a given P content. Anodic linear sweep voltammograms show more noble breakdown potentials and lower plateau current densities for the composites. The pit-arresting effect qr particle addition was assessed. More noble corrosion potentials and muck lower mass losses, pitting, and crevice formation were observed under erosion-corrosion conditions with normal impact of a sand containing slurry.