预钙化处理后的钛表面磷灰石涂层的形成

Formation of Apatite Coatings on Titanium Subjected to Pre-calcification

本研究采用碱液处理钛样品 ,并进行预钙化处理 ,在模拟体液 (SBF)中浸泡 ,能在较短时间内形成表面致密的磷灰石涂层。碱液处理使钛表面生成了钛酸钠及氧化钛等物质 ,在SBF中浸泡时 ,会发生水解而使表面形成带负电的Ti OH基团。预钙化处理使带负电的钛表面由静电引力而聚集了大量的Ca2 + 离子。Ca2 + 能吸引带负电的HPO2 -4到达表面 ,从而使表面附近能在较短时间内达到钙 磷过饱和。Ca2 + 离子又能使表面附近的pH值增大 ,Ca2 + 离子和HPO2 -4离子的活度积就增大 ,从而刺激了磷灰石晶体的成核与长大 。

Titanium samples treated with 5M NaOH aqueous solution at 60℃ were subjected to pre calcification and soaked in simulated body fluid (SBF). Dense apatite coatings covered the whole surfaces in short time. Sodium titanate and titanium oxide were formed after titanium samples were treated by NaOH aqueous solution and would be hydrolyzed to form negatively charged Ti OH group in SBF. Pre calcification can concentrated Ca 2+ ions on negatively charged titanium surfaces by electrostatic force. Ca 2+ could absorb negative HPO 2- 4 ions in SBF and increased pH value near the surfaces. Consequently, the Ca P supersaturation and the ion activity product of apatite increased and this stimulated the nucleation and growth of the apatite crystals and the formation of apatite coatings.