Analysis of the structure and characteristics of bioglass–iron oxide composite layers on Ti-6Al-4V alloy via electrophoretic deposition

Abstract

This study investigates the structural and functional properties of bioglass–iron oxide (Fe₃O₄) composite layers deposited on Ti-6Al-4V substrates via electrophoretic deposition (EPD). Suspensions with varying Fe₃O₄ contents (10, 15, 25, and 50 wt %) were prepared to identify the optimal composition. SEM and elemental mapping revealed that the B90-F10 sample (90 % bioglass, 10 % Fe₃O₄) produced a more uniform and denser coating compared to other compositions, while minimizing porosity and crack formation. The Vickers microhardness of the B90-F10 coating reached 321.3 ± 3.4 HV, higher than that of the pure bioglass coating B100-F0 (295.1 ± 2.3 HV). Surface roughness measurements showed that B90-F10 had a lower average roughness (0.82 ± 0.41 µm) than B100-F0 (2.10 ± 0.46 µm), indicating a smoother, more compact surface. The mean coating thickness for B90-F10 was 148.32 ± 0.02 µm, slightly greater than B100-F0 (140.01 ± 0.01 µm). Contact angle tests confirmed improved hydrophilicity, with B90-F10 showing a reduced contact angle (22.56°) compared to the uncoated substrate (55.16°). Electrochemical tests revealed that although coatings slightly reduced corrosion resistance compared to bare alloy due to residual porosity, the addition of Fe₃O₄ significantly increased charge transfer resistance, indicating better barrier performance than pure bioglass coatings. In vitro bioactivity tests confirmed enhanced formation of hydroxyapatite layers, critical for osseointegration. These findings highlight the coatings’ capacity to augment implant performance by improving mechanical durability, surface characteristics, and bioactivity, thus offering a valuable functional enhancement beyond the untreated substrate.