Titanium electrode impedance measurement

Impedance diagram technique. The polarization cell consisted in a transparent plastic tube that was adhered to the paint surface by means of a silicone sealer. The tube contained distilled water and a 25 cm platinized titanium sheet, which was used as auxiliary electrode. Measurements were made with... 

The assessment of the reported model for experimental passivation systems of say magnesium/magnesium perchlorate " and titanium/or titanium dioxide/sulphuric acid" has been made from the view-point of ffactality of the electrode surface and a good agreement between the model calculated complex plane impedance (Fig. 8 being a typical simulated plot) and the measured Nyquist-plots is obtained. 

Fig. 5. Analysis of the experimental steady-state current—potential and impedance-potential data from E = — 650 mV to E = —150 mV for a titanium rotating-disc electrode (45 Hz) in a solution of 3.0 M sulphuric acid at 65°C. (a) Steady state current-potential curve. The potentials are the measured potentials, (b) High-frequency double layer capacity-potential curve. The potentials are the measured potentials.

However, the active dissolution of titanium depends markedly on temperature in acid solution. At lower temperatures, the picture is not so clear. It is necessary to have a quantitative measure of the rate of the hydrogen reaction and the titanium dissolution reaction. The complete set of current-potential and impedance-potential data has been tested against the theory given above. The best strategy seems to be to fit to a single electrode reaction and then to look for deviations from the expected behaviour for a perfect redox reaction. A convenient way of doing this is to represent the electrochemical data as a standard rate constant-potential curve in conjunction with a double layer capacity-potential curve [21]. 

Fig. 6. Analysis of the experimental steady-state current-potential and impedance-potential data from E = -1300 mV to E = -600 mV for a titanium rotating-disc electrode (45 Hz) in a solution of 2 M perchloric acid, (a) Standard rate constant-potential curve calculated for the hydrogen evolution reaction on titanium assuming that DA = 7.5 x 10-5cm s and E° = —246 mV. The Tafel slope bc = 120 mV and the measured ohmic resistance was 0.3 ohm cm2. The potentials are the "true potentials, (b) Standard rate constant-potential curve calculated for the hydrogen evolution reaction on titanium assuming that DA = 7.5 x 10-5 cms-1 and E° = — 246mV. The Tafel slope bc = 211 mV and the measured ohmic resistance was 0.3 ohm cm2. The potentials are the "true potentials, (c) High-frequency double layer capacity-potential curve obtained from the impedance data. The potentials are the measured potentials.

Titanium Nitride (TiN) and Titanium (Ti) are the metals that are investigated as possible candidates for electrode arrays with Aluminium (Al) been used in our experiments for comparison purposes. Al which is being widely used in microelectronic industry as an interconnect, shows lower resistivity when combined with TiN. All of the measurements performed in the experimental setup are done on the same type of test die. There are four batches of this die, all of them are processed with different metals Al, TiN, Ti and one has aluminium covered with titanium nitride (Al-TiN). Following sections will provide you details about the experiments performed with the experimental setup on these materials and the results thereafter. Section 5.1 goes into detail about this test die. The test die was subjected to several tests and measurements the impedance of the different materials, the self-heating characteristics, the temperature coefficient of resistance (TCR), electromigration and endurance in a saline solution have all been measured out of which Electromigration, TCR and Impedance will be explained in detail in the later sections. 

McKubre and Syrett (1983, 1988) were the first to adapt the method of harmonic analysis for the control of the corrosion rate of cathodically polarized systems. They presented a theoretical description of the problem and developed the measuring technique by making measurements over a wide range of frequencies from 1 Hz to 10 kHz. The method applied by them is known in the literature as harmonic impedance spectroscopy (HIS). It is based on the measurement of the zero, first, second, and third harmonics of the current response of an electrode perturbed by a voltage sinusoid signal. The elaborate mathematical treatment of results theoretically gives the possibility of obtaining admittance data independent of the frequency. The numerical solution of a system of three equations with three unknowns allows the determination of required AE, b, and values, and finally the corrosion current. The authors of the HIS method carried out attempts to determine the corrosion rate of copper-nickel alloys, steel, and titanium under cathodic protec-... 

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