Evaluation of corrosion and tarnish on titanium alloy by electrochemical quartz crystal analyzer

虽然钛和钛合金以其优异的耐腐蚀性而闻名，但它们对过氧化氢和氟化物引起的变色的抵抗力并不强。本文研究了几种含过氧化物或含氟化物溶液对钛合金造成的变色和溶解。我们得出了以下结论。从晶体相、表面组成、释放的钛浓度、ph值等方面对含氟白蛋白溶液中钛的反应进行了验证。在样品的钝化膜上形成吸附的白蛋白膜，既保护了样品不受氟化物的攻击，又抑制了钛的释放。PGA和S12在碘中的耐蚀性降低，TI在氟中的耐蚀性降低。Ti-Cr合金中铬的含量增加了表面氧化膜中氧化铬的比例。我们认为，氧化铬含量高的氧化膜具有更强的抗氟腐蚀能力。高达3.5质量%的Cu与Ti-6Al-4V的合金化没有改变腐蚀行为。表面经过研磨或喷砂处理的样品优于表面为铸态的样品。两种溶液的色差和溶出率不同。在双氧水溶液中，Ti-55Ni和Ti-6Al-4V合金的颜色差异最大。Ti、Ti-0.15 pd、Ti- 7nb - 6al、Ti- 6al - 4v和Ti- 10cu合金在含氟溶液中表现出明显的颜色差异和溶出度。Ti-20Cr合金在两种溶液中的色差和溶出度最小。电化学石英晶体分析仪未发现色差与溶出度有显著相关性。

Although well known for their superior corrosion resistance, titanium and titanium alloys are not strongly resistant to discoloration caused by peroxide and fluoride. This study investigates the tarnish and dissolution of several titanium alloys caused by peroxide or fluoride containing solutions. We found following conclusions. The reactions on titanium in a solution containing fluoride and albumin are demonstrated based on crystal phase, surface composition, released titanium concentration, and pH. The formation of an adsorbed albumin films on the passive film of specimen not only protected the specimen from attack by the fluoride but also suppressed release of titanium. The corrosion resistance of PGA and S12 decreased in iodine, and that of TI decreased in fluoride. Chromium content in Ti-Cr alloys increases the ratio of chromium oxide in surface oxide films. We suggest that oxide films which have rich chromium oxide content have greater corrosion resistance to fluoride. Alloying up to 3.5 mass % Cu to Ti-6Al-4V did not change the corrosion behavior. Specimens with ground or sandblasted surfaces were superior to specimens with as-cast surfaces. The color difference and dissolution rates were different with the two solutions. In the hydrogen peroxide containing solution, the color difference was higher for the Ti-55Ni and the Ti-6Al-4V alloys than any other alloys. Ti,Ti-0.15Pd,Ti-7Nb-6Al,Ti-6Al-4V and Ti-10Cu alloys showed remarkable color differences and dissolution in the fluoride containing solution. Ti-20Cr alloy showed the least color difference and dissolution in both solutions. We could not find significant correlation between color difference and dissolution by electrochemical quartz crystal analyzer.