Corrosion behavior and mechanical properties of bioactive sol-gel coatings on titanium implants

• Published in: Materials Science & Engineering C Vol. 43; pp. 375 - 382
• Main Authors: Catauro, M., Bollino, F., Papale, F., Giovanardi, R., Veronesi, P.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.10.2014
• Subjects: Coated Materials, Biocompatible; Coatings; Corrosion; Corrosion process; Gels; Materials Testing; Mechanical properties; Microscopy, Electron, Scanning; Nanostructure; Organic–inorganic hybrid; Polarization tests; Prostheses and Implants; Protective coatings; Scratch and nano-indentation tests; Sol gel process; Spectroscopy, Fourier Transform Infrared; Surgical implants; Titanium; Wear resistance; Organic–inorganic hybrid; Polarization tests; Sol-gel process; Corrosion process; Scratch and nano-indentation tests
• ISSN: 0928-4931; 1873-0191
• DOI: 10.1016/j.msec.2014.07.044

Organic–inorganic hybrid coatings based on zirconia and poly (ε-caprolactone) (PCL) were prepared by means of sol-gel dip-coating technique and used to coat titanium grade 4 implants (Ti-4) in order to improve their wear and corrosion resistance. The coating chemical composition has been analysed by ATR-FTIR. The influence of the PCL amount has been investigated on the microstructure, mechanical properties of the coatings and their ability to inhibit the corrosion of titanium. SEM analysis has shown that all coatings have a nanostructured nature and that the films with high PCL content are crack-free. Mechanical properties of the coatings have been studied using scratch and nano-indentation tests. The results have shown that the Young's modulus of the coatings decreases in presence of large amounts of the organic phase, and that PCL content affects also the adhesion of the coatings to the underlying Ti-4 substrate. However, the presence of cracks on the PCL-free coatings affects severely the mechanical response of the samples at high loads. The electrochemical behavior and corrosion resistance of the coated and uncoated substrate has been investigated by polarization tests. The results have shown that both the coatings with or without PCL don't affect significantly the already excellent passivation properties of titanium. •ZrO2/PCL amorphous class I organic–inorganic hybrid coatings synthesis via sol-gel dip coating.•The presence of cracks on coatings and Young's modulus decreases for high PCL content.•PCL-rich coating are softer but recover a slightly higher amount of deformation work.•Coating adhesion proved satisfactory.•The coatings don't affect significantly the passivation properties of CP Ti grade 4.