Corrosion of aluminum

Acetic acid, fp 16.635°C ((1), bp 117.87°C at 101.3 kPa (2), is a clear, colorless Hquid. Water is the chief impurity in acetic acid although other materials such as acetaldehyde, acetic anhydride, formic acid, biacetyl, methyl acetate, ethyl acetoacetate, iron, and mercury are also sometimes found. Water significantly lowers the freezing point of glacial acetic acid as do acetic anhydride and methyl acetate (3). The presence of acetaldehyde [75-07-0] or formic acid [64-18-6] is commonly revealed by permanganate tests biacetyl [431-03-8] and iron are indicated by color. Ethyl acetoacetate [141-97-9] may cause slight color in acetic acid and is often mistaken for formic acid because it reduces mercuric chloride to calomel. Traces of mercury provoke catastrophic corrosion of aluminum metal, often employed in shipping the acid. 

Many stabilizer systems have been tailored to a particular industry need or for particular areas where dilution water quaUty is poor. These grades are heavily stabilized and may contain organic sequestering agents, ie, staimate, phosphates, and nitrate ions, so that the weak solutions produced by dilution from hard water retain acceptable stabihty. The nitrate is not a stabilizer, but it inhibits corrosion of aluminum storage tanks by chloride ion. 

The addition of stabilizers to tetrachloroethylene inhibits corrosion of aluminum, iron, and zinc which otherwise occurs in the presence of water (12). Where water in excess of the solubiUty limit is present, forming separate layers, hydrolysis and corrosion rates increase. System design and constmction materials should consider these effects. 

Stable in pure form after 3 months, caused extensive corrosion of aluminum, anodized aluminum, and stainless steel will corrode iron, bronze, and brass when moist. Titanium 71°C, 6 months, appeared good. Stainless Steel 43°C,... 

Davis, J. R., Corrosion of Aluminum and Aluminum Alloys. 1999, Materials Park, OH ASM International. 

There are many corrosion mechanisms which can take place in today s engines. The complexity has increased with the use of aluminum alloys in the head and block. Aluminum used in areas such as the head, where large quantities of heat are liberated to the coolant, is subject to a unique heat rejection corrosion. To protect against the heat rejection corrosion of aluminum, a coolant having special corrosion inhibitor systems must be used. 

Most engine coolants formulated to provide protection against the heat corrosion of aluminum contain elevated levels of silicate. Silicates are very sensitive to gelling or dropping out... 

Inorganic acids, bases, and salts with pH values <4 and >9 are not compatible with aluminum. Pitting corrosion of aluminum can occur when it comes in contact with salt water and copper halide salts. 

Inhibiting the corrosion of aluminum alloys by adding 1-5% of transition metals is a dramatic case of corrosion protection because of the small amounts of additives that are successful in reducing the corrosion rate by 1-2 orders of magnitude. It turns out that the alloying materials shift the pzc toward the positive side on the potential scale. Thus, in many practical situations, the alloys of the transition metals are in a... 

LiN(S02CF3)2 Electrochemically stable with a wide window and high conductivity solutions, but causes corrosion of aluminum in high voltage cathodes, which has limited use in hthium ion cells. 

H. Kaesche. Pitting Corrosion of Aluminum and Intergranular Corrosion of A1 Alloys, in Localized Corrosion. 1971. Williamsburg, VA NACE, Houston, TX. 

CLIMAT (classification of Industrial and Marine Atmospheres,21 gives data on uniform or galvanic corrosion of aluminum wire wound around threaded bolts made of steel or copper in an atmosphere of interest)... 

The dissolved oxygen in acid solution causes corrosion of aluminum the hydrogen, nitrogen, carbon dioxide and hydrogen sulfide have no effect. Hydrogen chloride is... 

Dealuminification. Recent investigations have shown the importance of the dealloying of S-phase (Al2CuMg) particles on the corrosion of aluminum aircraft alloys, specifically aluminum alloy 2024-T3. In 2024-T3, the S-phase particles represent approximately 60% of the particle population. These particles are of the order of 1 pm diameter, with a separation of the order of 5 pm representing an surface area fraction of 3%.56 The selective removal of aluminum and magnesium from these particles leaves behind a porous copper particle that becomes the preferential site for oxygen reduction.57, (Corcoran)5... 

Chemically, the film is a hydrated form of aluminum oxide. The corrosion resistance of aluminum depends upon this protective oxide film, which is stable in aqueous media when the pH is between about 4.0 and 8.5. The oxide film is naturally self-renewing and accidental abrasion or other mechanical damage of the surface film is rapidly repaired. The conditions that promote corrosion of aluminum and its alloys, therefore, must be those that continuously abrade the film mechanically or promote conditions that locally degrade the protective oxide film and minimize the availability of oxygen to rebuild it. The acidity or alkalinity of the environment significantly affects the corrosion behavior of aluminum alloys. At lower and higher pH, aluminum is more likely to corrode. 

Corrosion of Aluminum Components in the Glass Curtain Wall of a Building... 

Corrosion of aluminum by red fuming nitric acid is reduced by adding 4 percent by weight of hydrogen fluoride. Decomposition of concentrated acid is reduced by such substances as quaternary ammonium compounds, oiganic sulfones, inorganic persulfates, and organic sulfonium compounds.102... 

The corrosion of aluminum in water is normally prevented by the tightly adhering oxide layer that forms on the aluminum. If this layer were absent, as when aluminum is amalgamated with mercury in an anaerobic atmosphere, the following reaction occurs. 

---