Preparation of Bioactive and Porous Titanium Coating by Vacuum Plasma Spraying and Chemical Treatment

Abstract

Abstract This article describes a method of preparing bioactive and porous titanium coatings on titanium-based substrate using vacuum plasma spraying and chemical treatment in alkali solution. The porous titanium coating was fabricated in two-layer structure. The bond strength, average porosity and roughness (Ra) of the porous titanium coating are 55MPa, 30% and 21µm, respectively. The chemical treatment of as-sprayed titanium coatings was carried out in 5.0M NaOH solutions at 40 °C for 24h. The surface morphology and structure of the porous titanium coating before and after chemical treatment were examined by SEM and laser Raman spectroscopy. The treated titanium coating was immersed into SBF to evaluate its bioactivity by examining apatite formation on its surfaces. It was observed by SEM and TF-XRD that apatite was formed on the surface of the treated titanium coating after immersion in SBF. The spherical aggregates gradually grew large by consuming calcium and phosphate ions in SBF and covered the surface with increase in soaking time. Incorporation of CO32- ions into apatite crystal lattice was revealed by FT-IR. The results obtained indicated that net-like sodium titanate formed due to NaOH attack was responsible for apatite nucleation and growth. It is concluded that vacuum plasma spraying and subsequent chemical treatment is an effective way to produce bioactive and porous titanium coatings.