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Showing 1 to 20 of 48 for “"pitting corrosion"”.
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Local Environment in Pitting Corrosion of Aluminum
The pH and chloride microsensors were used to study propagation and repassivation of pits on pure aluminum in pH 11 NaCl solution. It was concluded that the pH inside a growing pit was around 2.7, and the chloride concentration was higher than the saturation concentration. After current to the pit …
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Pitting corrosion initiation in AISI 316 austenitic stainless steel
The initiation of pitting corrosion on AISI 316 stainless steel has been examined from a phenomenological viewpoint with emphasis on the role of the metal in this complex, interaction. A modified potentiodynamic technique was used to prepare specimens corresponding with a series of different points …
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Initiation, Propagation, and Mitigation of Aluminum and Chlorine Induced Pitting Corrosion
… and 4) try to determine the scope of this pitting problem in other distribution systems and on a national level. The first set of experiments clearly defined the controversial trends from earlier work. At certain pH values, the presence of chlorine and aluminum solids does seem to initiate …
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Experimental and Theoretical Investigation of Pitting Corrosion of Nickel in Chloride Solution
Pitting corrosion of nickel in 0.5M NaCl (pH 6.3) was investigated with use of single corrosion pits under both stagnant and flow conditions. The pit dissolution current was found to vary as a function of the applied potential. The pit surfaces were crystallographic, although the general shape of …
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Experimental and Theoretical Investigations of Electrode Shape Change Taking Place During Pitting Corrosion of Iron
… study included experimental measurements of corrosion pit shapes and theoretical calculations on the effect of pit shape on the mass transport of dissolved metal ions within pits. The system studied was pure iron in 1N H(,2)SO(,4) containing small amounts of chloride ion.
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The Effects of Fluid Flow on The Pitting Corrosion of Pure Iron in Acidic Chloride Media
The fluid flow effects on electrobright pitting of pure iron were investigated. A rectangular channel with minimized wall and entrance effects was used. The electrolytic solution consisted of an aqueous solution of 0.5 M sulfuric acid and 0.003 M sodium chloride. The experiments were carried out …
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Experimental and Numerical Studies of Single Manganese Sulfide Inclusions in Stainless Steel During Initiation of Pitting Corrosion
… acidification occurs after the initiation of pitting rather than trigger initiation. In addition, the model supported the hypothesis that pit initiation occurs due to the accumulation of an aggressive dissolved sulfur species, such as thiosulfate, as a result of inclusion dissolution. Critical …
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Experimental and Modeling Studies of the Stability of Pitting Corrosion on Pure Aluminum in Basic Chloride Solutions
The quasi steady state model was expanded to include homogeneous bulk reactions for hydrolysis and complexation reactions. The model predicted pH values of 2.5 to 3.0, values that agreed well with experimental measurements, only when the first two hydrolysis reactions of aluminum were included in …
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Pitting corrosion of aluminum-alloys at aluminum(3) iron inclusions: The effect of local chemical environment and transport phenomena
… local alkalization results in either ditching or pitting at the interfacial region between the particles and the aluminum matrix. A micro-disk electrode concept was adopted to calculate the oxygen reduction limiting current at intermetallics to explain the mechanism and predict the related …
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Pit initiation on passivated metal surfaces: crystallographic orientation and environmental effects
The susceptibility to pitting corrosion of tin and zinc was found to be dependent on the crystallographic orientation of the surface in chloride solutions. For tin single crystals, the(111) face showed the lowest critical pitting potential among five differently oriented surfaces. The critical …
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Interactions Between Copper and Chlorine Disinfectants: Chlorine Decay, Chloramine Decay and Copper Pitting
… the perspective of disinfectant decay and copper pitting corrosion. Sparingly soluble cupric hydroxide catalyzed the rapid decay of free chlorine, which in turn, led to production of less soluble and more crystalline phases of cupric hydroxide. The catalytic activity of the cupric hydroxide was …
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The influence of water composition on the pitting behaviour of newly developed corrosion resistant steels
… and nitrate ions. In order to minimise the pitting corrosion of piping and stoping machinery a compromise between selecting a suitable corrosion resistant material and treating the mine water to an acceptable level of corrosiveness is being sought.
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Assessment of the corrosion behaviour of alloys 825 and 625 in stagnant seawater-effect of temperature and welding
… wellheads, risers and valves. The outstanding corrosion resistance of alloy 825 against general and localised corrosion attack is attributed to its high Ni, Cr and Mo content. However, corrosion failures of alloy 825 equipment have been observed in offshore environments. Alloy 825 has good …
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Effect of plastic strain on the corrosion of X65 pipeline steel
Corrosion is an important mode of degradation and failure for iron alloys used in oil and gas pipelines. Pitting corrosion is a particular type of corrosion that is not well-understood and can play in important role in material failure. Research has shown that areas of increased plastic strain …
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Influences of Water Chemistry and Flow Conditions on Non-Uniform Corrosion in Copper Tube
… that can perpetuate certain types of non-uniform pitting corrosion in copper tube, specifically in waters with high chlorine and a high pH. These two parameters can further act synergistically to alter pitting propensities in copper pipes subjected to this type of water. A preliminary short-term …
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COLD SPRAYED COATINGS WITH DUAL NANOPARTICLE REINFORCEMENTS FOR WEAR AND CORROSION PROTECTION
… testing parameters is required. Additionally, corrosion testing was performed on cold sprayed samples for 500- and 2,000-hr trials in a salt fog chamber, revealing underlying pitting corrosion and galvanic corrosion vulnerabilities of the coatings. In the right application, the U.S. Navy could …
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Analytical studies of corrosion and wear resistant CrN/NbN superlattice PVD coatings.
… of commercial applications where both wear and corrosion resistance are important factors that are required. CrN/NbN nano-scale multilayered coatings have been successfully deposited at temperatures as low as 250°C on 304 stainless steel substrates. This has been achieved by the combined …
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In-vitro characterization of boronized titanium alloy by means of corrosion and electrochemical impedance spectroscopy methods in simulated body fluids
… titanium's wear resistance and also improves corrosion resistance. The target of this research was to characterize the corrosion characteristics of both unboronized and boronized titanium using both electrochemical corrosion methods and Electrochemical Impedance Spectroscopy (ELS) in simulated …
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The influence of tempering on the corrosion resistance of newly developed steels
… the effect of heat treatment on the localized corrosion resistance of the low carbon, chromium containing steels, designated 825, 102A and 122 which recently have been developed. The potentiodynamic polarization technique has been employed to determine the corrosion characteristics of the three …
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