The electrochemical behaviour of Ti‐13Nb‐13Zr alloy in various solutions

Abstract

The electrochemical behaviour of a near-b Ti-13Nb-13Zr alloy for the application as implants was investigated in various solutions. The electrolytes used were 0.9 wt% NaCl solution, Hanks' solution and a culture medium known as minimum essential medium (MEM) composed of salts, vitamins and amino acids, all at 37 8C. The electrochemical behaviour was investigated by the following electrochemical techniques: open circuit potential measurements as a function of time, electrochemical impedance spectroscopy (EIS) and determination of polarisation curves. The obtained results showed that the Ti alloy was passive in all electrolytes. The EIS results were analysed using an equivalent electrical circuit representing a duplex structure oxide layer, composed of an inner barrier layer, mainly responsible for the alloy corrosion resistance, and an outer and porous layer that has been associated to osteointegration ability. The properties of both layers were dependent on the electrolyte used. The results suggested that the thickest porous layer is formed in the MEM solution whereas the impedance of the barrier layer formed in this solution was the lowest among the electrolytes used. The polarisation curves showed a current increase at potentials around 1300 mV versus saturated calomel electrode (SCE), and this increase was also dependent on the electrolyte used. The highest increase in current density was also associated to the MEM solution suggesting that this is the most aggressive electrolyte to the Ti alloy among the three tested solutions.

Electrochemical corrosion response of a low carbon heat treated steel in a NaCl solution

“…3) can be used to provide quantitative impedance parameters in order to complement the qualitative analysis. In the last decade, such technique and particularly the proposed equivalent circuit have been intensively utilized by a number of researchers [11,15,19,[22][23][24][25][26][27][28][29][30][31].…”

“…The parameter Z CPE generally denotes the impedance of a phase element as Z CPE ¼ [C(jv) n ] À1 (where v is frequency and À1 n 1) and corresponds to the capacitance (1 Hz < f < 1 kHz) [15][16][17][18][19][22][23][24][25][26][27][28]. The n parameter seems to be associated with the non-uniform distribution of current as a result of roughness and surface defects [28,31,32]. By comparing the capacitances Z CPE(1) and Z CPE(2) of all heat treated steel samples it is possible to observe very similar values, i.e., all samples exhibit a same order of magnitude (of about 250 and 100 mF/cm 2 for Z CPE(1) and Z CPE(2) , respectively).…”

Enhanced Surface Precipitates on Ultrafine-Grained Titanium in Physiological Solution

“…Several authors [22][23][24] concerned porous layer formation during corrosion tests on titanium and titanium alloys. The feature of porous in this work can be demonstrated by the EIS result of insignificance of Warburg impedance for ECAPed specimens and easy diffusion behavior of corrosion product through the layer.…”

Corrosion behaviour of a new Ti‐6Al‐2Nb‐1Ta alloy in various solutions

“…Saline neutral media based on NaCl solutions of different concentration such as 240 g/L [4], 0.15 M [5], 0.5 M [6] and 0.9% (physiological serum) [7][8][9] were used as corrosive electrolytes for the study of the behaviour of the various alloys.…”

“…[5][6][7][8][9][10]; sulphate ions have a reduced corrosivity but the resistance of only a reduced number of alloys was studied.…”