Effect Of Chloride Contamination Research Articles

Chloride contamination of electrochemically grown zinc oxide thick films

Electrochemically grown zinc oxide thin films have applications in photovoltaics, optoelectronics, and piezoelectrics. Potentiostatic electrodeposition using zinc nitrate typically includes the use of an Ag/AgCl electrode to measure solution potential, which can leak silver chloride into the growth solution. The effects of chloride contamination in the growth solution on the properties of potentiostatically and galvanostatically grown zinc oxide films were investigated. The incorporation of the chloride was particularly notable for galvanostatically grown films deposited for longer than 2 h. The effects of the chloride on the electronic and crystallographic properties of the film were examined with scanning electron microscopy, X-ray diffraction, energy-dispersive spectroscopy, and resistance measurements. Using an Ag/AgCl electrode during the long-term growth of zinc oxide films contaminated the films with chloride, resulting in poor crystallinity, reduced chemical purity, inconsistent electrical conductivity, poor transparency, and a rough film surface.

Printed Circuit Board Surface Finish and Effects of Chloride Contamination, Electric Field, and Humidity on Corrosion Reliability

Corrosion reliability is a serious issue today for electronic devices, components, and printed circuit boards (PCBs) due to factors such as miniaturization, globalized manufacturing practices which can lead to process-related residues, and global usage effects such as bias voltage and unpredictable user environments. The investigation reported in this paper focuses on understanding the synergistic effect of such parameters, namely contamination, humidity, PCB surface finish, pitch distance, and potential bias on leakage current under different humidity levels, and electrochemical migration probability under condensing conditions. Leakage currents were measured on interdigitated comb test patterns with three different types of surface finish typically used in the electronics industry, namely gold, copper, and tin. Susceptibility to electrochemical migration was studied under droplet conditions. The level of base leakage current (BLC) was similar for the different surface finishes and NaCl contamination levels up to relative humidity (RH) of 65%. A significant increase in leakage current was found for comb patterns contaminated with NaCl above 70% to 75% RH, close to the deliquescent RH of NaCl. Droplet tests on Cu comb patterns with varying pitch size showed that the initial BLC before dendrite formation increased with increasing NaCl contamination level, whereas electrochemical migration and the frequency of dendrite formation increased with bias voltage. The effect of different surface finishes on leakage current under humid conditions was not very prominent.

Effects of Chloride Contamination on PEFCs

The performance and durability of PEFCs were investigated by introducing HCl and five different chloride salts into the air stream of an operating fuel cell. Under the same operating conditions and at a constant 28.5 mM chloride (Cl-) concentration, cell performance degradation can be ranked as HCl> AlCl3 > FeCl3 > CrCl3 > NiCl2, MgCl2. Water evaporation in the flow field surface was found to be causing precipitation of chloride salts. At lower RH, water content decreased and salt deposits completely blocked some of flow channels and caused death of the fuel cell. Moreover, contaminants crossed the GDL, reached the CCM surface, and caused significant performance drop.

Impacts of operating conditions on the effects of chloride contamination on PEM fuel cell performance and durability

Chloride contaminated fuel and/or air streams in an operating proton exchange membrane fuel cell can cause significant adverse effects on fuel cell performance and durability. This paper reports investigations of chloride contamination effects on PEM fuel cell performance and durability under a wide range of operating conditions, using various in-situ diagnostic measurements. Increases in current density and Cl− concentration as well as decreases in fuel cell RH were found to enlarge the severity of the chloride contamination effect. Temperature was also found to have a significant influence on the contamination effect.Electrochemical impedance spectroscopy was used as a diagnostic tool during the contamination tests to explore changes in cell component resistances. The results indicated that chloride contamination causes predominantly an increase in charge transfer resistance as well as an increase in mass transfer resistance. The membrane resistance was not found to be impacted by chloride contamination. As measured by cyclic voltammetry, the presence of chloride in the air stream significantly reduced the cathode electrochemical surface area, and this reduction is believed to be due to the adsorption of chloride on the Pt surface causing active site blockage and accelerated Pt dissolution and agglomeration via the formation of Pt–Cl complexes.

Evaluation of Protective Jackets Used on Reinforced Concrete Piles: Case Study of Hampton Roads Bridge and Tunnel

Corrosion of reinforced concrete piles located in a marine environment is of great concern, as it can reduce the load capacity of the piles and shorten their effective life. The Hampton Roads bridge and tunnel, located where the James River discharges into the Chesapeake Bay, was constructed with precast prestressed concrete piles, which have been exposed to a marine environment for 53 years. In the early 1980s, the Virginia Department of Transportation installed protective jackets on the piles to address the effects of chloride contamination and corrosion damage of the piles. The jackets were constructed by placing reinforcing mesh and a fiberglass stay-in-place form around an existing pile, and grouting the annular space with a mortar fill. The objective of these jackets was to prevent or mitigate corrosion activity by blocking water, oxygen, and chlorides from reaching the pile reinforcement. A study was undertaken to evaluate the effectiveness of the protective jackets through the use of visual evalua...