Basic Study on the Superplastic forming of Dental Prostesis

在850℃的超塑温度下，Ti-6Al-4V合金可以在很小的应力下产生较大的变形。这个温度大约是铸件熔化温度的一半。应用于钛铸造义齿的替代材料的制备。研究了Ti-6Al-4V合金的超塑性成形性能、力学性能和耐蚀性。采用超塑性成形技术制备Ti-6Al-4V合金义齿基托。超塑性成形模的生产采用了与牙科铸造几乎相同的工艺。超塑成型基托的配合性优于铸造Co-Cr合金基托。抗拉强度和屈服强度均高于钴铬合金铸件。采用氩气压力胀形试验，明确了超塑性成形性能与成形条件的关系。结果表明，在950℃，8kg/cm^2的温度下，60分钟的成形性足以制作出义齿基托。在义齿基托超塑性成形过程中，研究了纯钛钛合金和Co-Cr合金与Ti-6Al-4V合金的扩散结合。采用金、钯、银钯金合金焊料和金合金焊料等插入金属，成功地连接了纯钛和钛合金。扩散键合超塑性义齿基托具有良好的耐腐蚀性能。

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.