SEM, EDS and XPS studies of AC & DC PEO coatings obtained on titanium substrate

Abstract

Abstract The porous coatings may be fabricated on titanium substrate by Plasma Electrolytic Oxidation (PEO), known also as Micro Arc Oxidation (MAO), under AC or DC regimes. The obtained surfaces were characterized by Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), and X-ray Photoelectron Spectroscopy (XPS). This work has discussed the influence of electrolyte composition and of PEO type (AC-PEO or DC-PEO) on chemical composition of fabricated porous coatings as well as on their surface stereometry. The recorded results show clearly that the external porosity and roughness of obtained surfaces as well as metal-to-phosphorus ratios are different for different solutions and PEO processes, but for all PEO surfaces the bindings energies of titanium (Ti 2p), oxygen (O 1s), phosphorus (P 2p) may suggest that all the top nano-layers consist of Ti4+ and groups PO4 3–, and/or HPO4 2–, and/or H2PO4 –, and/or P2O7 2–.