齿科微晶玻璃的腐蚀机理及溶胶-凝胶防腐蚀涂层研究

利用体外试验方法以及SEM／EDAX、ICP、FTIR等分析技术，对氟硅碱钙石(fluorcanasite,K2Na4Ca5Si12O30F4)齿科微晶玻璃的腐蚀机理，以及溶胶-凝胶Al2O3，、TiO2及ZrO2涂层改善微晶玻璃抗侵蚀的效果进行了比较分析．研究表明，口腔溶液对该齿科微晶玻璃的侵蚀源于溶液中的H3O 离子与微晶玻璃表面的Na 及K 发生迅速的离子交换，从而形成结构疏松的表面富SiO2层，其Si-O网络进而被H2O分子所断开，使SiO2以可溶性硅胶形式溶解于溶液中．此反应导致大量的表面结构缺陷，从而降低了材料的强度和使用寿命。浸泡25天后微晶玻璃表面最终的反应产物是一层低结晶度的颗粒状碳酸羟基磷灰石Cal0(PO4)6(2OH-，CO3^2-)．溶胶-凝胶A12O3涂层具有显著的改善齿科微晶玻璃抗唾液腐蚀的作用。

Corrosion Mechanism of a Dental Glass-Ceramic in Artificial Saliva and Sol-Gel Derived Corrosion-Resistant Coatings

The corrosion mechanism of a dental glass-ceramic: fluorcanasite by oral fluid and the corrosion-resistant ability of different sol-gel derived coatings on the glass-ceramic were investigated in vitro using SEM/EDAX, ICP and FTIR techniques. The results obtained show that the corrosion of the glass-ceramic by the oral fluid comes of a rapid ion exchange between HsO+ in the solution and Na+ (K+) in the surface layer of the glass-ceramic, which results in a loose Si02-rich layer on the glass-ceramic. Part of SiO2 component dissolves into the solution in the form of Si(OH)4 because Si-O-Si network of SiO2-rich layer is broken by attack of H2O. A lot of surface defects are formed on the surface due to the corrosion of water, which decrease the strength and service life of the glass-ceramic in an oral environment. The final reaction product on surface of the glass-ceramic is hydroxyl-carbonate apatite (HCA). Sol-gel derived Al2O3 coating has a significant ability to enhance the chemical durability of the dental glass-ceramic.