Corrosion Behavior Of Casting Ti-24Nb-4Zr-7.9Sn Alloy

Titanium and titanium alloys are widely used in Clinical Medicine such as dental restoration, planting, orthodontics for their good mechanical properties, biocompatibility and processability. At present, domestic and international researchers pay close attention to the third-generationβ-type titanium alloy for its advantages of low elastic modulus, high strength, high toughness. A new titanium alloy, Ti-Nb-Zr-Sn alloy〔Ti-24Nb-4Zr-7.9Sn (wt%), TNZS〕which developed by Institute of Metal Research, Chinese Academy of Sciences has been proved to have excellent mechanical performance and biocompatibility, so it has a very good prospect of being produced as dental prosthesis and implant. However, the corrosion resistance of Ti-Nb-Zr-Sn alloy has not been reported yet till now. In this study, Ti-Nb-Zr-Sn alloy specimens produced by conventional lost-wax casting were evaluated and analyzed through the static immersion test, electrochemical corrosion test and stress corrosion test.Objective:In this study, Ti-Nb-Zr-Sn alloy was measured by the static immersion test, electrochemical corrosion test and stress corrosion test to evaluate and analyze its corrosion resistance in accordance with the oral use of metal corrosion resistance experimental standard, for providing laboratory basis for further clinical application. Commercial pure titanium was applied as the control group.Methods:1. After immersing in various solutions for a week, the metal surface morphology was observed by SEM, the composition of corrosion products were analyzed by XRD, and the elemental release was measured by ICP-MS.2. The self-corrosion potential, anodic polarization curves and electrochemical impedance spectroscopy were measured by Parstat2273 Electrochemical workstation and Faraday box.3. After immersing in acidic fluoride solution under stress conditions for a month, the metal surface morphology was observed by SEM, the composition of corrosion products were analyzed by XRD, and the weight changes before and after corrosion were measured by Electronic Analytical Balance.Results:1. Static immersion test results showed that the total elemental release from Ti-Nb-Zr-Sn alloy was lower than pure titanium in the same kind of soaking solution. To the same metal, the total elemental release in acidic fluoride solution was the highest, followed by neutral fluoride solution, again for lactic acid solution, and in artificial saliva was the lowest. The pictures of corrosive plane given by SEM showed that Ti-Nb-Zr-Sn alloy had a better signs of corrosion resistance compared with pure titanium in the same kind of soaking solution. And the mainly corrosion products on Ti-Nb-Zr-Sn alloy were Na3TiF6,Na2NbF6,Na2ZrF6,Na2SnF6, while the mainly corrosion products on pure titanium were Na3TiF6,Na2TiF6 and Na3TiOF5. 2. Electrochemical corrosion test results showed that Ti-Nb-Zr-Sn alloy had a higher self-corrosion potential, membrane resistance, transfer resistance and lower corrosion current density than pure Ti. And to the same metal, it had a highest corrosion resistance in artificial saliva, followed by lactic acid solution, again for neutral fluoride solution, and in acidic fluoride solution was the lowest.3. Stress corrosion test results showed that in acidic fluoride solution under stress conditions Ti-Nb-Zr-Sn alloy had a smaller weight changes than pure Ti. The pictures of corrosive plane given by SEM showed that Ti-Nb-Zr-Sn alloy had a better signs of corrosion resistance compared with pure titanium in acidic fluoride solution under stress conditions. And the mainly corrosion products on Ti-Nb-Zr-Sn alloy were Na3TiF6,Na2NbF6,Na2ZrF6,Na2SnF6, while the mainly corrosion products on pure titanium were Na3TiF6.Conclusion:Cast Ti-Nb-Zr-Sn alloy exhibited excellent corrosion resistance in static immersion test, electrochemical corrosion test and stress corrosion test. It can meet the request of dental material and has an excellent foundation for further promoting.