| Titanium and titanium alloys have been widely used in the manufacture of implants and other dental prostheses due to their good mechanical properties,corrosion resistance,and biocompatibility.Ti-6Al-4V alloy,which was first used in the dental field,has physiological toxicity due to the release of aluminum ions and vanadium ions in service,which can cause adverse reactions such as inflammation and pain.Nb as aβstable element,has solid solution strengthening effect to titanium alloy,which can not only improve the strength of titanium alloy,but also improve the corrosion resistance and biocompatibility of titanium alloy.As a commonly used neutral element,Sn is often added together with other elements to play a complementary role.The selection of alloy elements Nb and Sn to design a new dental alloy is expected to improve the corrosion and wear resistance of the alloy.In this study,the Ti-Nb-Sn dental material was prepared by mechanical alloying combined with mold sintering,and the Ti-6Al-4V alloy was used as the contrast material.Firstly,the effects of high-energy ball milling process on the properties of Ti-13Nb-5Sn powder mixture,microstructure,corrosion resistance and wear resistance of Ti-13Nb-5Sn alloy were studied.Then,the influence rules and mechanisms of Nb content on the microstructure,corrosion resistance,wear resistance and biocompatibility of the materials were studied under the optimal milling time.As the ball milling time increased from 3 h to 48 h,the mixed Ti-13Nb-5Sn powder was uniformly distributed,Nb diffused into the Ti lattice to form Ti（Nb）displacement solid solution,Sn fully diffused into the Ti and Nb lattice to produce Ti（Nb Sn）solid solution.The relative density of Ti-13Nb-5Sn alloys increased gradually,and the equiaural structure gradually changed into widmanstatten structure.After grinding for 48 h,the alloy showed higher corrosion potential(Ecorr),lower corrosion current density(Icorr),larger polarization resistance（Rp）,and wider passivating interval（ΔE）in artificial saliva,showing better corrosion resistance.The alloy had higher hardness,lower friction coefficient,smaller wear depth and wear rate,showing better wear resistance.The microstructure study showed that the Ti-Nb-Sn alloys were composed ofαphase andβphase.With the increase of Nb content from 13 wt.%to 25 wt.%,the main peak changed fromα-Ti toβ-Ti,and the widmanstatten structure gradually changed into needle-like structure and the pureβzone appeared.Electrochemical tests showed that Ti-Nb-Sn alloys exhibited similar electrochemical behaviors in artificial saliva and acidic artificial saliva solutions,indicating that acid environment had little effect on the alloys.The polarization curves showed that the addition of Nb was beneficial to enhance the corrosion resistance of the alloys,and the Mott-Schottky curves showed that Nb could improve the stability of the alloy passivation film.The AC impedance spectrum showed that the more Nb content,the more obvious the near-capacitance response characteristics of the alloys.X-ray photoelectron spectroscopy showed that Ti O2,Nb2O5 and Sn O2 passivation films were formed on the alloy surface.With the increase of Nb content,the Ti-Nb-Sn alloys changed from hydrophilic to hydrophobic,which further verified that the increase of Nb content was beneficial to improve the corrosion resistance of the alloys.With the increase of Nb content,the grain boundary of Ti-Nb-Sn alloys gradually changed from rod-like to stripαphase,the grain area gradually increased,and the relative density and hardness of the alloys showed a decreasing trend.The friction and wear tests showed that the friction coefficient of the alloys increased in both air and artificial saliva medium,but the average value of wet friction coefficient was lower,which indicated that artificial saliva had good lubrication effect.The morphology of wear marks showed that the wear mechanisms of the alloys were mainly abrasive wear and adhesive wear,but the wet friction wear degree was light and the wear rate was low.The cells adhered and spread on the surface of Ti-25Nb-5Sn alloy,and the cell viability of Ti-13Nb-5Sn and Ti-25Nb-5Sn alloys were higher than that of the control group,indicating that Ti-Nb-Sn alloys were conducive to cell proliferation and growth,and had good cell compatibility in vitro. |
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