PORCELAIN BONDING OF TITANIUM ALLOYS

钛因其优异的耐腐蚀性、良好的生物相容性和重量轻而非常适合用于牙科修复体的应用。然而，纯钛的瓷粘接存在一些问题。本研究的目的是利用β钛合金和低膨胀陶瓷开发瓷结合钛合金体系。首先，研究了纯钛与瓷的结合强度和反应。分别在低压空气、低真空+氩气和高真空+氩气条件下烧制纯钛上的两种商品瓷。在任何烧成条件下，纯钛的瓷结合强度都远低于镍铬合金。由于钛表面氧化层容易剥落，钛的膨胀率可能低于陶瓷。选用膨胀率低、氧化层薄的β -钛牙科铸造合金Ti-2OCr-0.2Si和Ti-25Pd-5Cr作为瓷结合金属。拔出试验表明，β钛合金与瓷的结合强度明显高于纯钛。其中Ti- 25Pd-5Cr合金的结合强度最高。但如果瓷器是在这些钛板上烧制的，它就会被小的弯曲应力破坏。然后通过掺加可浇注陶瓷来减少瓷的膨胀。这种低膨胀的瓷器与钛合金牢固地结合在一起。

Titanium appears to be highly suitable for dental prosthetic applications because of its excellent corrosional resistance, good biocompatibility and light weight. However, there are problems in porcelain bonding of pure titanium. The object of this study was to develop the porcelain bonding titanium alloy system using beta titanium alloys and low expansion ceramics.First, the bonding strength and reactions between pure titanium and porcelain were investigated. Two kinds of commercial porcelains on pure titanium were fired in low pressure air, low vacuum + argon gas or high vacuum + argon gas. In any firing conditions, porcelain bonding strength of pure titanium was much lower than those of Ni-Cr alloys. Be cause the titanium surface oxide layer spalled easily and the expansion of titanium might be lower than that of porcelain.Then, beta-titanium dental casting alloys, Ti-2OCr-0.2Si and Ti-25Pd-5Cr, were selected as porcelain bonding metals because of those lower expansion and thinner oxide layer. The bonding strength between the beta titanium alloys and porcelain by pull-out test were much higher than that of pure titanium. Especially the bonding strength of Ti- 25Pd-5Cr alloy showed the highest value. But if the porcelain was fired on these beta titanium plate, it was fractured and split by small bending stress. Then the porcelain expansion was reduced by mixing castable ceramics. This low expansion porcelain bonded firmly with the beta-titanium alloys.