sulphide (1 ppm) and ammonia (10 ppm), as sea water pollutants, on the corrosion of A. A. HASAN 70Cu-30Ni alloy owing to sulphate reducing bacteria (SRB). Potential-time and linear F. AL-SABTI polarisation measurements revealed that the presence of SRB makes the corrosion potential more active by ~250 mV and increases the corrosion rate by a factor of ~6•5. T he addition of inorganic sulphide to sea water inoculated with SRB caused a significant ennoblement of the corrosion potential which was associated with a decrease in the corrosion rate, while the addition of ammonia did not aVect the corrosion potential although it caused a significant increase in the corrosion rate. Sulphate reducing bacteria had a pronounced eVect on the potentiodynamic polarisation through shifting the corrosion potential to a more active value and eliminating the active-passive transition. However, the active-passive transition peak was retained when sulphide was added to sea water inoculated with the bacteria. In the presence of ammonia, the hysteresis loop was retained in the absence of a well defined active-passive transition. W ith increase in the exposure time to sea water inoculated with SRB, the impedance and phase angle peak decreased. In the presence of sulphide, the impedance increased in the high frequency region and the frequency dependence of the phase angle showed two time constants. In the presence of ammonia, the impedance behaviour experienced significant changes in terms of a decrease in impedance and a shift in the phase angle peak towards lower f requencies. Scanning electron microscopy (SEM) examinations revealed the formation of a patchy layer of bacterial biofilm and corrosion products during exposure to SRB containing sea water. T he formation of this layer was associated with depletion of nickel from the alloy. In the presence of inorganic sulphide, micropits and intergranular attack were seen within crevices in an adherent corrosion product layer. In the presence of ammonia, the alloy initially suVered from shallow localised attack which gradually spread to cover the whole metal surface, revealing grain boundaries, twin boundaries, and slip steps.

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In response to environmental concerns associated with the buildup of arsenic sludge used in A. AL-HASHEM the monoethanolamine (MEA) CO 2 removal unit at a refinery in Kuwait, two organic based J. A. CAREW inhibitors have been evaluated as potential replacements for the inorganic sodium arsenate A. HASAN used earlier. T he inhibitors were evaluated for UNS N0400 (Monel 400) in f resh MEA solution saturated with an 85H 2 -15CO 2 gas mixture at 40°C using electrochemical impedance spectroscopy, potentiodynamic polarisation, and weight loss techniques. Interfacial impedance data obtained at low frequencies were marginally higher when the two organic inhibitors were added. T he percentage eYciency obtained by the potentiodynamic method was 66% for an amide based inhibitor and 15% for an amine based inhibitor. Weight loss data also indicated that the corrosion rate of N0400 in the MEA solution with the amide based inhibitor was lower than that with the amine based inhibitor.T he authors are in the

The electrochemical behaviour and stress corrosion cracking (SCC) susceptibility of 70 : 30 Cu-Ni alloy were investigated in 18% monoethanolamine (MEA) solutions at 60 and 90uC. The MEA solutions were used under the deaerated, aerated and H 2 S saturated conditions. Potentiodynamic polarisation experiments showed that the alloy exhibits an active-passive transition in both the deaerated and aerated solutions at pH 9. On the other hand, it underwent active anodic dissolution in the absence of passivity in the same solutions when the pH was increased to 12, and also in the H 2 S saturated solution. Open circuit potential measurements showed that the corrosion potentials reached steady state values relatively quickly and that the alloy remained active under all conditions of test. Linear polarisation measurements revealed that the corrosion rates were generally higher in the aerated solutions than in the deaerated ones and tended to be higher in solutions of pH 12 than at pH 9. The corrosion rates were significantly higher in the H 2 S saturated solution than in the other two solutions. The 70 : 30 Cu-Ni alloy was found to be susceptible to transgranular SCC in the 90uC aerated MEA solution of pH 9 at applied potentials in both the active-passive transition and the transpassive regions. The mechanism of cracking was attributed to stress assisted dissolution of copper from the alloy matrix.

A.C electrical conductivity and dielectric properties for poly(vinyl alcohol) (PVA) /poly (ethylene oxide) (PEO) blends undopedand doped with multi-walled carbon nanotube (MWCNTs) withdifferent concentrations (1, and 3 wt %) in the frequency range(25x103 - 5x106 Hz) were investigated. Samples of (PVA/PEO)blends undoped and doped with MWCNTs were prepared usingcasting technique. The electrical conductivity measurements showedthat σA.C is frequency dependent and obey the relation σA.C =Aωs forundoped and doped blends with 1% MWCNTs, while it is frequencyindependent with increases of MWCNTs content to 3%. Theexponent s showed proceeding increase with the increase of PEOratio (≥50%) for undoped blends samples, while s value for dopedblends exhibits to change in different manner, i.e. s increases andreach maximum value at 50/50 PVA/PEO, then decreases forresidual doped blends samples with 1% MWCNTs on the other handthe exponent s decrease and reach minimum value at 50/50PVA/PEO for samples doped with 3% MWCNTs, then return toincrease. The results explained in different terms.