Corrosion behavior of dental titanium restrations and implant in fluorode-containing solution

钛因其优异的化学稳定性而被用作生物相容性材料，如牙科植入物或修复物。然而，钛在预防性含氟环境中的腐蚀成为一个问题。为了明确氟浓度和pH对Ti、Ti- 6a1 - 4v和Ti- 6ai - 7nb腐蚀行为的影响，在不同浓度（0.05% ~ 2.0%）和pH值（2.0 ~ 7.2）的NaF溶液中进行了阳极极化试验和浸泡试验。用电感耦合等离子体质谱法分析了测试溶液中溶解Ti的浓度。结果表明，随着氟浓度的增加，Ti或钛合金在酸性溶液中的耐蚀性明显降低。在氟浓度和pH值的限制下，钛的腐蚀行为由“无腐蚀性”转变为“腐蚀性”。这一关系表明，在已知氟化物浓度和pH值的情况下，钛和钛合金是否会发生腐蚀。Ti在含氟溶液中的腐蚀与氢氟酸（HF）浓度有关。当溶液中的HF浓度高于约30 ppm时，Ti的钝化膜被破坏。在含氟酸性溶液中，Ti和Ti- 6ai - 7nb合金的耐蚀性相似，但Ti- 6ai - 4v合金的耐蚀性较差。在含氟酸性溶液中，Ti-0.2 pd和Ti- 10mo -0.2 pd合金比纯Ti、Ti- 6ai - 4v和Ti- 6ai - 7nb合金具有更高的耐腐蚀性。认为钯的表面富集促进了钛的再还原，从而提高了材料的耐蚀性。

Titanium is used as a metal for biocompatible materials such as the dental implant or restorations because of an excellent chemical stability. However, the corrosion of Ti in prophylactic fluoride-containing environment comes into a problem. To clarify the effect of fluoride concentration and pH on the corrosion behavior of Ti, Ti-6A1-4V and Ti-6AI-7Nb, anodic polarization tests and immersion tests were carried out in NaF solution of various concentrations(0.05%-2.0%) and pH values(2.0-7.2). The concentrations of dissolved Ti in the test solutions were analyzed by inductively coupled plasma mass spectroscopy. The results showed that corrosion resistance of Ti or Ti alloys markedly decreased in the acidic solution as the fluoride concentration increased. There were obvious limits of fluoride concentration and pH value at which the corrosion behavior of titanium changed from "Non- corrosive" to "Corrosive". This relation indicates whether Ti and Ti alloys will corrode or not, if the fluoride concentration and pH value are known in the concerned environment. The corrosion of Ti in the solution containing fluoride depended on the concentration of hydrofluoric acid (HF). When the HF concentration in the solution was higher than about 30 ppm, the passivation film of the Ti was destroyed.In the fluoride-containing acidic solution, corrosion resistance of Ti and Ti-6AI-7Nb alloy were similar but that of Ti-6AI-4V alloy was inferior to them. Ti-0.2Pd and Ti-10Mo-0.2Pd alloys had a higher corrosion resistance than pure Ti, Ti-6AI-4V and Ti-6AI-7Nb alloys in the fluoride-containing acidic solution. It is thought that corrosion resistance is improved because the surface enrichment of Pd promotes a repass ivation of Ti.