Basic Study on the Superplastic forming of Dental Prostesis

Ti-6Al-4V合金在850 ℃的超塑性温度下，在较小的应力作用下，可以发生较大的变形，该温度约为铸造用合金熔化温度的一半。并将其应用于口腔修复体的制作，作为钛铸造修复体的替代品。研究了Ti-6Al-4V合金的超塑成形性能、力学性能和耐蚀性能。采用超塑成形技术制备Ti-6Al-4V合金义齿基托。超塑成形模的制造过程与牙科铸件的制造过程几乎相同。超塑成形义齿基托的适合性优于铸造钴铬合金义齿基托。抗拉强度和屈服强度均高于钴铬合金铸件。采用氩气加压胀形试验研究了超塑成形性与成形条件的关系。结果表明，在950 ℃、8 kg/cm ~ 2的超塑成形条件下，60 min的成形时间就足以制作义齿基托。采用金、钯、Ag-Pd-Au合金钎料和金合金钎料等插入金属成功地连接了纯钛和钛合金。扩散粘结超塑基托具有上级耐腐蚀性能。

Ti-6Al-4V alloy can be deformed easily and enormously by small stress at superplastic temperature of 850ﾟC.This temperature is about half of the melting temperature of for casting. It was applied for fabricating a dental prosthesis as substitute for titanium casting prosthesis. The superplastic formability, mechanical properties and corrosion resistance of Ti-6Al-4V alloy was investigated. Ti-6Al-4V alloy denture base was fabricated by superplastic forming. Almost the same procedure as for dental casting was employed in producing the superplastic forming die. The fits of superplastic forming denture base was better than that of casting Co-Cr alloy denture casting. The tensile strength and yield strength were higher than those of Co-Cr alloy castings. Argon gas pressure bulgde test was employed to make clear the relations between the superplastic formability and the forming conditions. The results showed that the formability of 60 minute at 950 ﾟC, 8kg/cm^2 might be enough to fabricate a denture base.During the superplastic forming of denture base, diffusion bonding of pure titanium Titanium alloys and Co-Cr alloy to Ti-6Al-4V alloy was investigated. Pure titanium and Titanuim alloys were successfully bonded by using insert metals such as gold, palladium, Ag-Pd-Au alloy solder and gold alloy solder. The diffusion bonding superplastic denture base showed superior corrosion resistance.