The structural and bio-corrosion barrier performance of Mg-substituted fluorapatite coating on 316L stainless steel human body implant

• Published in: Applied surface science Vol. 288; pp. 331 - 340
• Main Authors: SHARIFNABI, A, FATHI, M. H, EFTEKHARI YEKTA, B, HOSSAINALIPOUR, M
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 2014
• Subjects: Austenitic stainless steels; Biocompatibility; Coating; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fluorapatite; Heat resistant steels; Human body; Infrared spectroscopy; Physics; Scanning electron microscopy; Stainless steels; Sol―gel; Ion release; Corrosion; Mg-substituted fluorapatite; Dip coating; 316L stainless steel; Sol-gel process; Corrosion behavior; Stainless steels; Film growth
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.10.029

In this study, Mg-substituted fluorapatite coatings were deposited on medical grade AISI 316L stainless steel via sol-gel dip coating method. Phase composition, crystallite size and degree of crystallinity of the obtained coatings were evaluated by X-ray diffraction (XRD) analysis. Fourier transform infrared (FTIR) spectroscopy was also used to evaluate functional groups of the obtained coatings. The surface morphology and cross-section of the final coatings were studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectroscopy was used to determine elemental chemical composition of the obtained coatings. In order to determine and compare the corrosion behavior of uncoated and Mg-substituted fluorapatite coated 316L stainless steel, electrochemical potentiodynamic polarization tests were performed in physiological solutions at 37 plus or minus 1 degree C. Moreover, the released metallic ions from uncoated and coated substrates were measured by inductively coupled plasma-optical emission spectrometry (ICP-OES) within 2 months of immersing in Ringer's solution at 36.5 plus or minus 1 degree C as an indication of biocompatibility. The results showed that fluoride and magnesium were successfully incorporated into apatite lattice structure and the prepared coatings were nanostructured with crystallinity of about 70%. Obtained coatings were totally crack-free and uniform and led to decrease in corrosion current densities of 316L stainless steel in physiological solutions. In addition, coated sample released much less ions such as Fe, Cr and Ni in physiological media. Therefore, it was concluded that Mg-substituted fluorapatite coatings could improve the corrosion resistance and biocompatibility of 316L stainless steel human body implants.