Evaluation of Localized Corrosion of Zirconium in Acidic Chloride Solutions

Istrate

et al. 2015

Materials & Corrosion

Electrochemical behaviour of Zr5Ti, Zr25Ti and Zr45Ti, with and without surface modification were investigated for dental applications. All untreated and thermal oxidized alloys in Na2CO3 at 890 °C were tested by electrochemical impedance spectroscopy (EIS) performed in 10% carbamide peroxide solution. In addition, scanning electron microscopy (SEM) was employed to observe the surface morphology before and after 8 hours immersion time in carbamide peroxide solution. The electrochemical corrosion parameters obtained from the EIS indicated a typical passive behaviour for untreated and thermal oxidized ZrTi alloys. Higher impedance values were observed for thermal oxidized ZrTi alloys compared to untreated materials. The thermal oxidized Zr45Ti alloy appears to possess superior corrosion resistance than the thermal oxidized Zr25Ti and Zr5Ti alloys in carbamide peroxide solution.

Section: Introductionmentioning

confidence: 99%

Effect of thermal oxidation on electrochemical corrosion behaviour of ZrTi alloys for dental applications

Mareci

Istrate

et al. 2015

Materials & Corrosion

“…Both metals usually have their surfaces covered by passivating thin oxide films that are spontaneously formed in air or in electrolytes at open circuit [23,24]. Though Zr offers superior corrosion resistance over most other metals in different electrolytes [25], this metal is susceptible to localized corrosion induced by Clions [26,27]. In terms of biomaterial applications, the most inconvenient characteristics are related to degradation, which occurs due interaction of the material with body or physiological fluids that typically present concentrations of ca.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical characterization of ZrTi alloys for biomedical applications

Izquierdo

Santana

et al. 2013

Electrochimica Acta

The electrochemical behaviour of three ZrTi alloys (Zr5Ti, Zr25Ti and Zr45Ti) in Ringer's solution has been investigated. Their resistance against localized corrosion has been determined from cyclic potentiodynamic polarization (CCP) and electrochemical impedance spectroscopy (EIS) measurements, whereas scanning electrochemical microscopy (SECM) was applied to investigate the local reactivity of the passive films developed on the materials, and scanning electron microscopy (SEM) was employed to characterize the surface morphology of the alloys subjected to anodic polarization. An increased reactivity could be detected with SECM when the metal samples were polarized at +0.50 VSHE, though the extent of this feature greatly depended on the nature of the metallic material. At 37 0 C, the Zr5Ti alloy was susceptible to localized corrosion. Though Zr25Ti alloy presented rather low pitting potential, the spontaneous corrosion potential of the material was sufficiently negative to require overpotentials around 600 mV for breakdown to occur. Finally, the Zr45Ti alloy exhibited a larger passive range in the polarization curve, and it was resistant to localized corrosion.

“…Unfortunately, zirconium is susceptible to localized corrosion induced by chloride ions too [20,21]. In contrast, the addition of titanium to zirconium reduces the susceptibility of the later towards localized corrosion, and the passive films developed by the ZrTi alloys provided a more insulating barrier towards electron transfer at the surface of the alloys compared to Ti when the oxide layers were spontaneously formed at their corresponding OCP values during immersion in Ringer's physiological solution [1].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical characterization of ZrTi alloys for biomedical applications. Part 2: The effect of thermal oxidation

Izquierdo

Mareci

et al. 2013

Electrochimica Acta

Oxidation in air of ZrTi alloys at 500 ºC for 2 h produces oxide-covered materials with a very high corrosion resistance in Ringer's solution at 37 ºC. The oxide layers present a double-layer structure, comprised by a thin and very compact inner layer of ca. 5 nm thickness, and a less compact, more porous and thicker outer layer. The thickness of the outer layer greatly varies with the composition of the base ZrTi alloy, but has very little influence in the overall electrochemical behaviour of the material. The nature of the oxide layer is a mixture of ZrO2 and TiO2, and no evidence of higher oxidation states of the metal could be found using XRD data. Anodic dissolution through the passive layers formed on the oxidized alloys is greatly diminished compared to those measured from the untreated materials, allowing all the alloying ratios between Zr and Ti to be potentially considered for implant application. The combination of alloying with titanium and oxidation in air at 500 ºC resulted in the materials that do not exhibit the characteristic susceptibility of zirconium towards the initiation of localized corrosion processes in aqueous chloride-containing electrolytes even for anodic polarizations up to +1.00 VSCE, a value well above the highest polarization experienced in the human body. Though all the oxidized alloys exhibited remarkable corrosion resistances, the best behaviour was found for oxidized Zr45Ti.