| Owing to the good mechanical properties,excellent corrosion resistance and biocompatibility,titanium and titanium-based alloys are widely used as biomedical implant materials.However,due to the high elastic modulus and low wear resistance of titanium-based alloys,they are still facing with some problems in clinical application,for instance,the risk of"stress shielding effect"caused by elastic modulus mismatch and the problem of"particle disease"resulted from corrosive wear.Because of the unique amorphous structure,Ti-based metallic glasses exhibit relatively-low elastic modulus and high wear resistance,which can alleviate the existing problems of traditional titanium-based alloys to some extent and thus show a good prospect in the application of biomedical implant materials.In this study,the mechanical properties,corrosion,wear and tribocorrosion behaviors of the Ti Zr Cu Pd BMG?Ti-based BMG?were systematically investigated.The interaction mechanism of the wear and corrosion of the Ti-based BMG in simulated human fluid was also discussed.Based on these results,the corrosive wear resistance of the Ti-based BMG was further improved by oxidation heat treatment.Firstly,the mechanical properties and dry wear behaviors of the Ti-based BMG were studied.The Ti-based BMG demonstrates a yield strength approaching 2.3 GPa,a Young's modulus of about 95 GPa,and a hardness of over 7.2 GPa.It is seen that the Ti-based BMG displays a lower Young's modulus and a higher strength than those of the Ti-6Al-4V alloy.The wear rate of the Ti-based BMG under dry friction condition(6.1×10-8mm3/mm·N)is lower than that of the Ti-6Al-4V alloy(3.5×10-7mm3/mm·N),which verifies a higher wear resistance of the Ti-based BMG.The dry wear mechanism of the Ti-based BMG is abrasive wear and oxidation wear.The high wear resistance is attributed to the high hardness and fracture toughness of the Ti-based BMG.Secondly,the wear behaviors of the Ti-based BMG in the simulated human body solution were studied,and the interaction mechanism between the wear and corrosion was illustrated.The wear rate of the Ti-based BMG under wet friction condition is 8.0×10-8mm3/mm·N,which is lower than that of the Ti-6Al-4V alloy.The wear mechanism under wet friction condition is abrasive wear and corrosion wear.The electrochemical experimental results show that the Ti-based BMG displays a corrosion potential and low corrosion current density in the phosphate buffer saline?PBS?solution,indicating its good corrosion resistance.The high corrosion resistance of the Ti-based BMG is ascribed to the formation of highly protective Ti O2and Zr O2passivation film on the alloy surface.The tribocorrosion results show that the Ti-based BMG exhibit a low passivation current density,indicating the high stability of the passivation film which can reduce the accelerated effect of corrosion on wear.Finally,the electrochemical and corrosive wear behaviors of the Ti-based BMG after heat-treated by the surface oxidation at 300??T-300?and 400??T-400?were investigated.After heat treatment at 300?,particle-shape oxides were generated on the surface of the Ti-based BMG.With the increase in heating temperature,the oxide particles on the surface increased and the oxygen content on the surface of the alloy increased significantly.The experimental results of friction and wear showed that the wear resistance of the T-300 alloy and T-400 alloy was enhanced as compared with that of the as-cast Ti-based BMG.The wear resistance of the T-300 alloy was the best under the dry friction condition with a lowwear rate of 4.1×10-8mm3/mm·N.Under wet friction in the PBS solution,the wear resistance of the T-400 alloy was the best among the three samples with a low wear rate of 2.2×10-8mm3/mm·N.The electrochemical results showed that with the increase in heating temperature,the corrosion potential of the Ti-based BMG increases,and the corrosion current density of the Ti-based BMG decreases,indicating an increase in thecorrosion resistance increases.The tribocorrosion behaviors show that the T-300 and T-400 alloys exhibit a low passivation current density under the sliding.Moreover,no pitting corrosion was found on the surface of the T-300 and T-400 alloys during the tribocorrosion.With the increase in the heating temperature,the pitting resistance of the alloys increases,which is the main reason for the high corrosion resistance of the oxidized Ti-based BMG.In summary,the Ti-based BMG exhibits good mechanical properties,high corrosion and corrosive wear resistance.Oxidation heat treatment can effectively improve the wear and corrosive wear resistance of the Ti-based BMG,which can promote its application in the field of biomedical implant materials. |
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