New compounds of corrosion inhibitors namely amino-N’-(3-(hydroxyimino)butan-2-ylidene)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbohydrazide (1), amino-N’-(thiophen-2-ylmethylene)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbohydrazide (2) and amino-N’-(1-(pyridin-2-yl)ethylidene)-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbohydrazide (3) were synthesized and its inhibiting action on the corrosion of carbon steel in 1 M hydrochloric acid at 25ºC was investigated by various corrosion monitoring techniques. A Potentiodynamic polarization, AC impedance and electrochemical frequency modulation methods have been used. Potentiodynamic polarization studies showed that these derivatives were mixed type inhibitors. The effect of temperature on the corrosion behavior of carbon steel in 1 M HCl with the addition of these compounds were studied in the temperatures 25 and 45ºC. The adsorption of these inhibitors on carbon steel surface from hydrochloric acid obeyed the Langmuir adsorption isotherm. Quantum chemical method is used to explore the relationship between the inhibitors molecular properties and their inhibition efficiency.
SF EXPO — The most professional and highly recognized surface finishing industry pageant came to a satisfactory ending on May 13th at Guangzhou Poly World Trade Center. The 3-day exhibition attracted 13,749 visitors and 289 exhibitors from 38 countries and regions. The number of visitors renews the record again. Although SF EXPO 2015 comes to a successful ending, the negotiation and cooperation between visitors and exhibitors has just started. Continue reading…
The development of a low temperature liquid metal battery based on ionic liquids namely, sodium-bis(trifluoromethylsulfonyl)imide (Na[TFSI]) in tetraethylammonium-bis(trifluoromethylsulfonyl) imide ([TEA][TFSI]) will be discussed. Such a battery should be easily accessible for fluid flow measurements which is still a challenge with the conventional high temperature systems. Cells comprising a Na negative electrode, 20 mole% Na[TFSI] in [TEA][TFSI] ionic liquid electrolyte and a Pb-Bi eutectic positive electrode were constructed and operated at 160 °C. Galvanostatic cycling experiments were conducted at low C rates (C/26) for 13 h corresponding to 50% depth of discharge. A discharge capacity of 565 mAh/g was found. Furthermore electrochemical impedance spectroscopy was used to characterize the aging of the cells.
In this paper, we attempt to present a new approach and analytical relation between perimeter-to-area ratio (P/A) and the plated thickness using Variable Area Window (VAW) test mask for improved thickness estimation. Although, the approach is illustrated using selective plating of gold films by varying two dimensional patterned windows on metallised silicon surface as an example, yet the method can be applied to other cases also. The method includes selective electroplating of gold in rectangular and circular windows wherein P/A of patterned shapes (squares, rectangles and circles) has been varied from 0.001 cm-1 to 0.4 cm-1 i.e. a factor of 400, a range normally used for practical modern MEMS devices. Experiments show that in general the thickness increases with increasing P/A because of current crowding. However, in contrast to using current density for control of this current crowding as reported in literature, we report that by careful design of mask pattern and improved material parameters, one can control and even achieve a slope reversal in the plot of thickness vs. P/A. The increase in thickness as measured by slope of linear fit is about 3 µm/(P/A in µm-1) for sharp edges compared to about 0.8 µm/(P/A in µm-1) for curved edges within the experimental errors. The general applicability of these relations to practical cases is confirmed by analysing the previously reported trends of data from the literature on Ni films using similar patterned shapes.
The use of allium sativum (garlic) as a green inhibitor for the corrosion of low carbon steel in 1M HCl has been studied using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) techniques and weight loss measurements. Allium sativum has been proved to be good inhibitor. This reduction in the corrosion rate was due to the formation of an external layer formed by S-containing film present in the extract which was adsorbed physically on the metal surface. Allium sativum acted as a mixed type of inhibitor. The inhibition efficiency increases with increasing the inhibitor concentration, but decreases with raising the temperature. The adsorption of allium sativum on the metal surface follows Temkin’s adsorption isotherm. From EFM the causality factors are very close to theoretical values which indicate that the measured data are of good quality. Nyquist plots show a single capacitive loop in uninhibited and inhibited solutions.