Aluminum containers corrosion

Aluminum containers are recommended for many appHcations because of the very hard, corrosion-resistant oxide coating. They are deficient in only one respect once the protective skin has been penetrated, aluminum corrosion accelerates. 

Fruit and vegetable juices packed with 21-26 in. of vacuum and stored in uncoated aluminum cans caused severe corrosion as shown in Table III. The corrosion rate brought about by the juices depends more on the nature of the organic acid present and the buffering capacity of the juice than on the total titratable acidity (11). The use of coated aluminum containers considerably minimized corrosion problems. Product control under extended storage conditions may be achieved by using specific chemical additives. However, more work is needed in this area before final conclusions can be reached. 

Foods such as meat, fish, and some vegetables contain sulfur-bearing amino acids that form volatile sulfur compounds during processing and storage. When these compounds react with iron, a black precipitate forms on the container and in most instances darkens the food. A small piece of aluminum welded to the tinplate can has been used to prevent container corrosion and sulfide staining in commercially canned hams. In this case, the aluminum acts as a sacrificial anode and stops the reaction with tin and iron that otherwise could occur at the small exposed tinplate areas (14). 

Corrosion has been encountered infrequently to date and has been a surface type, as opposed to pitting corrosion that can result in perforations. Entrapped air in the beverage or in the cans headspace increases the corrosive action of the product according to Koehler et at (21). As with beer and other canned foods, aluminum ends provide electrochemical protection when combined with tinplate or tin-free-steel can bodies. The level of iron pickup is reduced while the amount of aluminum dissolved in soft drinks increases without detrimental effect. Aluminum containers with vinyl epoxy and vinyl organosol coatings are compatible with carbonated soft drinks. 

Frozen Foods. Corrosion caused by the reaction of foods with aluminum containers is unusual if the products are handled and stored at 0°F or lower. However, the inevitable bad handling of frozen foods during commercial distribution causes undesirable thawing. In this condition, not only does the food deteriorate, but it can also attack the container. Such unwanted reactions can be effectively controlled by using coated aluminum containers. Since aluminum is highly compatible with frozen fruits and citrus juices, it has been used extensively as a liner for fiberboard composite cans, as complete aluminum cans, or as ends in combination with steel can bodies in the frozen food industry. 

Stable in steel or aluminum containers. Rapidly corrosive to brass at 65°C will corrode steel at 0.001 in./month at 65°C. 

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... 

Friedel-Crafts reactions are highly corrosive, and the aluminum-containing residues are difficult to dispose. 

Copper alloys C44300, C44500, C61300, C68700, C70600 and C71500 series are more corrosion resistant than copper in natural waters. In general these alloys contain corrosion-resistant metals such as nickel or metals such as iron and aluminum, which... 

The corrosion resistance of stainless steels and nickel-based alloys in aqueous solutions can often be increased by addition of chromium or aluminum. " Chromium protects the base metal from corrosion by forming an oxide layer at the surface. Chromium is also considered to be an important alloying metal for steels in MCFC applications. Chromium containing stainless steel, however, leads to the induced loss of electrolyte. Previous studies done to characterize the corrosion behavior of chromium in MCFC conditions have shown the formation of several lithium chromium oxides by reaction with the electrolyte. This corrosion process also results in increased ohmic loss because of the formation of scales on the steel. Aluminum additions similarly have a positive effect on corrosion resistance. " However, corrosion scales formed in aluminum containing alloys show low conductivity leading to a significant ohmic polarization loss. 

The best performance for all IL media tested was observed with stainless steel type 304 which proved to be resistant in all water-free and water-diluted systems. The Ni-based alloy C22 generally also proved to have a high resistance to most IL-containing media. For carbon steel and aluminum the corrosiveness of IL media depends strongly on the chemical structure of the cationic moiety and the nature of the anion in the ionic liquid. In water-free quality (water-content below 1%)... 

Corrosion of Aluminum by Halogenated Solvents. Both liquid and vapor-phase halogenated solvents used for the production of ICs and PCs corrode aluminum-containing components. Water contamination of the solvent increases the time to corrosion on the one hand and increases the corrosion rate on the other hand. Dilution of the stabilized solvents with alcohol results in the breakdown of halogenated solvents and the decomposition product, chloride ion corrodes aluminum, and aluminum-copper alloys. 

Add 2 mL of 6 M sodium hydroxide, NaOH, solution to the fifth small test tube containing aluminum. CAUTION This concentration of NaOH solution is caustic and corrosive toward vour skin and clothing. If anv spills or spatters occur onto vour skin or clothing, immediately rinse the affected area thoroughly with water. Describe what you observe in TABLE 36.lA. Potassium hydroxide reacts with aluminum in a similar way. A1(0H)4" is the aluminum-containing product. This simple tetrahedral anion is favored at pH > 13, but more complex aluminate anions involving polymers with octahedral... 

Typically, titanium alloys have been the materials of choice for medical implants. The Ti-6A1-4V alloy is generally considered chemically inert, compatible with human tissue, and resistant to corrosion by human body fluids. However, the small percentages of vanadium and aluminum contained in the alloy are potentially toxic. Pure titanium is chemically and biologically more compatible with human fluids and tissue, but it is too weak for prostheses that must bear heavy loads, such as leg or hipbone implants. 

Fig. 19.26 Effect of novel functional electrolyte containing NI as an additive designed to suppress the aluminum substrate corrosion...

Bronzes are copper-tin alloys which upon prolonged contact with the atmosphere form a dark patina that is much appreciated in the art world. In presence of certain pollutants such as chloride the dark patinas eventually turn to green. Aluminum-containing bronze forms surface films containing AI2O3 which improves the resistance to erosion corrosion compared to copper or brass. 

In principle, the aluminum-containing alloys of magnesium should all be capable of providing corrosion peiform-ance competitive with that established for high-purity alloys AZ91D and AZ91E in die cast and sand cast applications (i.e., <0.25 mm/yr (10 mpy) in ASTM B 117 salt spray), if the critical contaminants are controlled at appropriate levels [9,17]. 

Aluminum is suited for containment and production of many chemicals and foods. References 8-10 should be consulted to determine compatibility with specific chemicals. Caution is advised concerning compatibility with a specific chemical that has become contaminated. For liquid chemicals, especially with the use of closed aluminum containers, the resistance of the aluminum container can differ in the liquid and vapor phases and at the Uquid-vapor interface. If the corrosion performance is unknown, all three conditions should be investigated. 

The fluorocarbons are generally compatible with most of the common metals except at high temperatures. At elevated temperatures, the following metals resist fluorocarbon corrosion (and are named in decreasing order of their corrosive resistance) Inconel, stainless steel, nickel, steel, and bronze. Water or water vapor in fluorocarbon systems will corrode magnesium alloys or aluminum containing over 2 percent magnesium. These metals are not recommended for use with fluorocarbon systems in which water may be present. 

Figure 3-5. Schematic representation of the corrosion of aluminum containing iron in dilute and concentrated NaCl solution.

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