The Corrosion Resistance Of Ni-Cr Alloy, Ni-Cr Alloy With Titanium And Alloys After Surface Treatment

Objective: 1.To study the effect of surface treatment such as titanium nitrogen(TiN) coating and gold-plating on corrosion resistant of Ni-Cr alloy and Ni-Cr Alloy With Titanium. 2. to evaluate the difference in corrosion resistance between Ni-Cr Alloy and Ni-Cr Alloy with Titanium(commercial named Titan alloy) .Methods: in order to evaluate the variation in corrosion resistance of different dental casting alloy, including Ni-Cr and Ni-Cr/TiN and Ni-Cr/gold, Titan and Titan/TiN, the electrochemical corrosion test, metal ion releasing test and scanning electron microscope (SEM) were used. Polarization curves was drawed and current density of corrosion(Icorr)was tested. The type and concentration of metal ions released from alloy was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES),then the data were converted to ug/cm2 .The surface morphology of smooth group was observed by SEM before test, after the electrochemical test and after immerse test.Results: 1. the electrochemical test showed that⑴Icorr decreased obviously after coated with TiN and gold compared with that of uncoated(P<0.05). As for Ni-Cr alloy, Icorr of TiN coating group was significantly lower than that of gold-plating group(P<0.05).⑵Icorr of smooth group was significantly lower than that of rough group(P<0.05).⑶Icorr of Titan alloy was significantly lower than that of Ni-Cr alloy(P<0.05). In addition, Polarization curves of TiN coating group and Titan alloy group uncoated appear obvious passivation, and TiN coating group were obviously wider. 2. metal ion release test showed that:⑴The amount of ion release decreased obviously after coated with TiN and gold compared with that of uncoated(P<0.05). For Ni-Cr alloy, The amount after TiN coating was significantly lower than that of gold-plating in smooth group(P<0.05), but higher in rough group(P<0.05).⑵The amount of ion released of uncoated group had no significant difference between smooth group and rough group(P>0.05), but The amount of coated groups in smooth group were significantly lower than in rough group(P<0.05).⑶The amount of ion release of Titan alloy were significantly lower than that of Ni-Cr alloy(P<0.05). 3. SEM showed that pore increased obviously after test compared with pre-test in uncoated group and it was inter-crystal corrosion; but it significantly decreased after coated with TiN and gold.Conclusion: 1. TiN coating and gold-plating could significantly/dramaticly improve the corrosion resistance of Ni-Cr alloy and Ni-Cr alloy with titanium. 2. The corrosion resistance of...