| As a biomaterial, titanium is widely used in dentistry due to their high strength toweight ratio, good fatigue properties, excellent corrosion resistance and biocompatibility.But there are still several problems as a dental material, such as low wearresistance, inelegant color and poor corrosion resistance in fluoride environment.etal.Plasma nitriding and TiN-coated treated casting titanium in order to improvethe surface properties. In our previous study, the microhardness and tribologicalproperties, biosafety and clinical application of pure titanium after duplex treatment havebeen investigated. In the present study, we investigated it,s effect on corrosion resistanceof titanium in fluoride-containing environment by potentiodynamic polarization techniqueand ion release experiment.Part1. Compound nitriding pure casted titanium and the electrochemical corrosionof the coatingTreated and untreated casted pure titanium specimens after random sampling wereimmersed in the solution. After specimens being immersed in the solution for0.5h,polarization curve depicted and the current density of corrosion (Icorr) and the electric potential of corrosion (Ecorr) were measured. After electrochemical experiment，themicrostructure was observed by SEM, the element of the surface was analyzed by EDS.Results showed that the Icorrs of casted titanium in the artificial saliva of differentfluoride concentrations were1530.23±340.12,2290.36±320.10, and4130.52±230.17nA,and the Ecorrs were-0.93±0.10,-0.89±0.21and-0.57±0.09V. The Icorrs of castedtitanium by compound treatments were2.62±0.64,7.37±3.59and10.76±6.05nA. TheEcorrs were-0.21±0.04,-0.17±0.03and-0.22±0.03V, respectively. The SEM confirmedthe microstructure in the casted titanium was much severely than in casted titanium bycompound treatments, the microstructure in the casted titanium and casted titanium bycompound treatments corroded more and more heavily with increasing of fluorideconcentrations. But there were no fluoride detected in titanium surface by EDS. All theseshowed that the increase of fluoride concentrations influence the corrosion resistance ofboth treated and untreated casted titanium negatively, but plasma nitriding and TiN-coatedduplex treatments can significantly increase the corrosion resistance of casted titanium.Part2. The ion release of pure casted titanium by duplex treatmentAfter short-term and long-term immersion, we determined the titanium ions releasedfrom titanium specimens and analyzed the datas. The results of short-term immersionshowed that the amount of titanium ions released from the untreated and treated titaniumin non-fluoride saliva was too small to be detected after being immersed. But after beingimmersed in fluoride saliva, there were2.02μg/cm2,5.80μg/cm2titanium ions releasedfrom untreated titanium and0.36μg/cm2,0.97μg/cm2from treated titanium at the first5minutes and the third5minutes. The results of long-term immersion showed that theamount of titanium ions released in F-0mg/L from the untreated and treated titanium were2.36±0.10、3.17±0.43μg/cm2and1.24±0.02、1.81±0.12μg/cm2at274h and456hrespectively, and the amount of titanium ions released in F-2000mg/L from the untreatedand treated titanium were20.75±1.13、27.57±2.31μg/cm2and4.58±0.42、5.45±0.33μg/cm2at274h and456h respectively. All these showed that, in fluoride artificial saliva,the amount of titanium ions released was increased than non-fluoride artificial saliva, butduplex treatment slowed down the speed of ions release and improve the corrosion resistance of titanium.The two parts experiments metioned above investigated the effect of duplextreatment on corrosion resistance of titanium in by Potentiodynamic polarization techniqueand ion release. The results showed that duplex treatment can improve the corrosionresistance of titanium significantly. |
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