Containing Chlorides

Modestov A D, Zhou G-D, Ge FI-FI and Loo B FI 1995 A study by voltammetry and the photocurrent response method of copper electrode behavior in acidic and alkaline solutions containing chloride ions J. Electroanal. Chem. 380 63-8... 

The carrier stream consists of an acidic solution of Hg(SCN)2 and Fe +. When a sample containing chloride is injected into the carrier stream, the chloride displaces the thiocyanate from Hg(SCN)2. The displaced thiocyanate then reacts with Fe + to form the reddish colored Fe(SCN) + complex, the absorbance of which is monitored at a wavelength of 480 nm. Sampling rates of approximately 120 samples/h have been achieved with this system. 

There is often a period before corrosion starts in a crevice in passivating metals. This so-called incubation period corresponds to the time necessary to establish a crevice environment aggressive enough to dissolve the passive oxide layer. The incubation period is well known in stainless steels exposed to waters containing chloride. After a time period in which crevice corrosion is negligible, attack begins, and the rate of metal loss increases (Fig. 2.8). 

In some reports Gallionella have been associated with manganese and iron deposits that also contain chloride. It has been postulated that deep undercut pits on stainless steels (especially at welds) containing such deposits are indirectly caused by these bacteria, since the iron-manganese deposition can be accelerated by Gallionella. In spite of numerous literature citings, however, evidence for stainless steel... 

Aluminum triethyl (triethyl aluminum) [97-93-8] M 114.2, b 69°/1.5mm, 76°/2.5mm, 129-131°/55mm, d 0.695, n 1.394. Purified by fractionation in an inert atmosphere under vacuum in a 50cm column containing a heated nichrome spiral, taking the fraction 112-114°/27mm. It is very sensitive to H2O and should be stored under N2. It should not contain chloride which can be shown by hydrolysis and testing with AgN03. [J Am Chem Soc 75 4828 51937953 NMR J Am Chem Soc 81 3826 7959.]... 

A high-nickel alloy is used for increased strength at elevated temperature, and a chromium content in excess of 20% is desired for corrosion resistance. An optimum composition to satisfy the interaction of stress, temperature, and corrosion has not been developed. The rate of corrosion is directly related to alloy composition, stress level, and environment. The corrosive atmosphere contains chloride salts, vanadium, sulfides, and particulate matter. Other combustion products, such as NO, CO, CO2, also contribute to the corrosion mechanism. The atmosphere changes with the type of fuel used. Fuels, such as natural gas, diesel 2, naphtha, butane, propane, methane, and fossil fuels, will produce different combustion products that affect the corrosion mechanism in different ways. 

When reviewing the materials of construction consider external corrosion concerns. Chloride stress cracking of stainless steel can be initiated by insulation capturing chlorides or insulation that contains chlorides (stainless steel should be primed). A weather barrier is needed. The principle here is to understand the potential hazards and their mechanisms. 

Potassium chloride is crystallized from sea bitterns containing chlorides of potassium, sodium and calcium by ammoniation (Jagadesh etai, 1992). This process is less energy intensive and more efficient than by fractional crystallization by evaporation, as the ammonia used is recovered by distillation. Crystallization produces a better quality product in terms of both size and purity than by other methods. 

Chlorid, n. chloride (esp., an -ic chloride, as contrasted with Chloriir). -chlor, n. chlorine in the form of chloride. chLoridhaltlg, a. containing chloride(s). Chloridlauge, /. chloride solution, chlorierbar, a. capable of chlorination, chlorieren, c.f. chlorinate Bleaching) chemick ... 

Boiler salts can contain chloride ions. When carried over into the steam (e.g. during priming) this can result in chloride stress corrosion cracking of austenitic stainless steel expansion bellows. In steam systems where freedom from chloride cannot be guaranteed, bellows... 

Tingley, I. L, Corrosion Resistance of Type 329 Stainless Steel in HNO3 containing Chloride Ion , Corrosion, 19, 408t (1963)... 

Frazer, M. J. and Langstaff, R. D., Influence of Cupric Ions on the Behaviour of Surface-active Agents Towards Aluminium , Bril. Corrosion J., 2, II (1%7) Szklarska-Smialowska, Z. and Janik-Czachor, H., Pitting Corrosion of 13Cr-Fe Alloy in Na2S04 Solutions Containing Chloride Ions , Corros. Sci., 7, 65 (1967)... 

Fig. 3.15 Idealised form of a potentiostatic anodic polarisation curve for stainless steels as determined in a neutral solution containing chloride...

Textile applications Much use has been made of non-molybdenum Cr-Ni steels in dyeing. On the other hand, many dyeing solutions contain chlorides or other corrosive substances such as formic acid, and here it is often wiser to use the 316 group. 

In practice, pitting of nickel and nickel alloys may be encountered if the corrosive environment contains chloride or other aggressive ions and is more liable to develop in acidic than in neutral or alkaline solutions. In acidic solutions containing high concentrations of chloride, however, passivity is likely to break down completely and corrosion to proceed more or less uniformly over the surface. For this reason nickel and those nickel alloys which rely on passivity for their corrosion resistance are not resistant to HCl. 

The deliberate growth of tin oxide or mixed oxide films in both acid and alkaline solutions has been reviewed recently . The effect of additions to alkaline solutions on their attack on tin has been considered as has the tendency for pitting corrosion to occur in solutions containing chloride ions" . In connection with this, potential pH diagrams for Sn-H O-Cl systems have been published . 

Turning now to the acidic situation, a report on the electrochemical behaviour of platinum exposed to 0-1m sodium bicarbonate containing oxygen up to 3970 kPa and at temperatures of 162 and 238°C is available. Anodic and cathodic polarisation curves and Tafel slopes are presented whilst limiting current densities, exchange current densities and reversible electrode potentials are tabulated. In weak acid and neutral solutions containing chloride ions, the passivity of platinum is always associated with the presence of adsorbed oxygen or oxide layer on the surface In concentrated hydrochloric acid solutions, the possible retardation of dissolution is more likely because of an adsorbed layer of atomic chlorine ... 

The fracture mode of stress-corrosion cracks in austenitic stainless steels can be transgranular, intergranular or a mixture of both. One of the earliest environments found to cause problems was solutions containing chlorides or other halides and the data due to Copson (Fig. 8.30) is very informative. The test solution for that data was magnesium chloride at 154°C the alloys contained 18-20alloy with a composition of approximately 18Cr-8Ni has the least resistance to cracking in this environment. 

In general it is wise to avoid as far as possible, the use of incompatible metallic joints in marine and offshore practice, since these are often in contact with seawater or water that contains chlorides which are effective corrosive electrolytes. It is prudent to take very considerable precautions to prevent corrosion at the design and installational stages. However, the widely diverse properties required of the materials used in such installations make it impracticable to avoid all such joints. 

The chloride ion is the most frequent cause of contact corrosion, since chlorine is present in the many chlorinated plastics, and is also frequently retained in residual amounts from reactive intermediates used in manufacture. Thus epoxides usually contain chloride derived from the epichlor-hydin used as the precursor of the epoxide. In addition to the contaminants referred to in Table 18.18, various metal and ammonium cations, inorganic anions and long-chain fatty acids (present as stabilisers, release agents or derived from plasticisers) may corrode metals on contact. 

For instance, nanoparticles of silver chloride have been synthesized by mixing two mi-croemnlsions, one containing silver ions and the other containing chloride ions. It was shown that the average particle size, the polydispersity and the number of particles formed depend on the intermicellar exchange rate and/or the rigidity of the surfactant shell [228],... 

A galvanic cell can be constructed from a silver-silver chloride electrode in contact with a solution containing chloride anions and an iron electrode in contact with a solution containing iron(IIt) cations. 

Anodic oxygen evolution (also anodic chlorine evolution, in solutions containing chlorides)... 

In discovery the most common base salt is the HCl salt. It is common in biology to use buffers containing chloride and the chloride content of the gastric contents is about 0.15 M. It often happens that the common ion effect of chloride suppresses the solubility of an HCl salt. This is a 100% solvable problem in pharmaceutical sciences. 

Copolymers of mainly acrylic acid and 2% to 20% by weight of itaconic acid are described as fluid loss additives for aqueous drilling fluids [138]. The polymers have an average molecular weight between 100,000 and 500,000 Dalton and are water dispersible. The polymers are advantageous when used with muds containing soluble calcium and muds containing chloride ions, such as seawater muds. 

---