Growth Hydroxyapatite Onto Ti-6Al-4V alloys and 316L Stainless Steel Substrates by Chemical Method

• Main Authors: Shih-Hsun Lin, 林士勛
• Other Authors: Yao-Shan Hsu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/60701743327152041026

碩士 === 大同大學 === 材料工程研究所 === 89 === To coat hydroxyapatite layer onto biomedical metals surface by plasma–sprayed method could enhance the bioactivity and enable bio-histogenesis. But caused by the post-heat-treatment and since there are not chemical bondings between metal/ceramic interfaces, so that degradation of the coated hydroxyapatite layer is inevitable. This project try to use simply chemical method to replace the plasma-sprayed technique to coat hydroxyapatite on Ti-6Al-4V alloy or 316L stainless steel substrates. In the present study, a sample chemical method was established for inducing bioactivity of Ti-6Al-4V and 316L stainless steel substrates. When these substrates were treated with 10M NaOH aqueous solution and subsequently heat treated at 600℃ and 700℃ a thin sodium titanate or sodium iron layer was formed on their surfaces. Thus, treated substrates formed a dense and uniform bonelike hydroxyapatite layer on their surfaces in simulated body fluid (SBF) or increasing Calcium and phosphate concentration of simulated body blood (CP-SBF) for 37℃ and 80℃ respectively . The study will produce chemical-bonding hydroxyapatite coating on metal substrate then to investigate the metal/ceramic interface and coating mechanisms. The process is mainly assumed to occur in some stages: The hydroxyapatite formation on the surfaces of metal substrates was assumed induced by a hydrated titania or ferric oxide which was formed by an ion exchange of the alkali ion in the alkali titanate and ferrous ion layer and the hydronium ion in SBF or CP-SBF. The resultant surface structure changed gradually from the outermost apatite layer to the inner metals through a hydrated titania or ferrous oxide and titanium oxide or ferric oxide layer. This provides not only the strong bonding of the hydroxyapatite layer to the substrates but also a uniform gradient of stress transfer from bone to the implants. The present chemical surface modification is therefore expected to allow the use the bioactive metals as artificial bones even under load-bearing conditions. Since we find that increasing ion concentration and temperature in the solution can accelerate coating rate. Further, we obtain optimal reactive condition as Ti-6Al-4v substrate subjected to 10M NaOH treatment at 60℃ for 24 h and heat treatment at 600℃ for 1h, and subsequently soaked in CP-SBF for 1-4 weeks and 316L substrate subjected to 10M NaOH treatment at 60℃ for 24 h and heat treatment at 600℃ for 1h, and subsequently soaked in SBF for 1-4 weeks.