Corrosion inhibitors surface preparation

An amide-type corrosion inhibitor is prepared as follows Methylmethacrylate is converted with tallow triamine or tallow tetramine at 80° to 90° C into the corresponding amides. After completion, the temperature is raised to initiate the polymerization reaction [1350]. The polymerization reaction is performed at temperatures up to 200° C. The polymer controls the corrosion of metal surfaces in contact with a corrosive hydrocarbon-containing medium. 

Lower aliphatic amines are widely used as intermediates for the synthesis of herbicides, insecticides and drugs or can be applied as rubber accelerators, corrosion inhibitors, surface active agents etc. [l]. The most widespread method for the preparation of lower aliphatic amines involves the reaction of ammonia with an alcohol or a carbonyl compound in the presence of hydrogen. The most common catalysts used for reductive amination of alcohols, aldehydes and ketones contain nickel, platinum, palladium or copper as active component [ I — 3 ]. One of the most important issues in the reductive amination is the selectivity control as the product distribution, i.e. the ratio of primary to secondary or tertiary amines, is strongly affected by thermodynamics. 

Nature of the metal surface Clean, smooth, metal surfaces usually require a lower concentration of inhibitor for protection than do rough or dirty surfaces. Relative figures for minimum concentrations of benzoate, chromate and nitrite necessary to inhibit the corrosion of mild steel with various types of surface finish have been given in a recent laboratory studyThese results show that benzoate effectiveness is particularly susceptible to surface preparation. It is unwise, therefore, to apply results obtained in laboratory studies with one type of metal surface preparation to other surfaces in practical conditions. The presence of oil, grease or corrosion products on metal surfaces will also affect the concentration of inhibitor required with the... 

The preparation of a corrosion inhibitor in the solid form allows the development of a new technique of continuous intensive anticorrosive protection for gas and oil pipelines, as well as for acidizing operations of oil wells [746]. The controlled dissolution of the solid inhibitor creates a thin protective layer on the metallic surface that prevents or minimizes the undesirable corrosion reactions. 

We can define pretreatment as the initial conditioning period whereby a corrosion inhibitor is applied to the metal surfaces of the cooling system. Pretreatment conditions must be conducive to the rapid formation of the protective barrier. The conditioning procedure should involve (1) the cleaning and preparation of metal surfaces, and (2) the actual application of higher than normal inhibitor concentrations. 

OTHER COMMENTS used as a solvent for casein, albumin, shellac, and sulfur used in the manufacture of surfactants, emulsifying agents, wetting agents, dispersants, corrosion inhibitors, detergents, and textile surface treatments used in preparation of dyes, synthetic waxes, resins, insecticides, and asphalt wetting agents also used as an inhibitor in antifreeze solutions has been used as a pharmaceutical aid. 

Reductive alkylation of nitrile by secondary amines having the same or different alkyl chains is another alternative for tertiary amine preparation. Many other special cationics, N-alkyl monoaza crown ethers [53], for example, can be classified as tertiary amines. The surface-active tertiary amine compounds are used as such (as corrosion inhibitors, dopes, antistatics, reagents in mineral processing) or as semifinished products. Alkyldimethylamines and dialkylmethylamines were run on a commercial level, e.g., by Albemarle (former Ethyl Corp.) as ADMA Tertiary Amines and DAMA Tertiary Amines , respectively. 

The amidoamines possess reactive amine sites that allow for the cross-finking of epoxy resins in coatings, adhesives, and other applications. They are also used in asphalt to improve performance in road surfacing. Amidoamines and substituted imidazolines, prepared by the reaction of DETA or TETA with TOFA or crude tall oil, find use as corrosion inhibitors in petroleum production operations. Amidoamines have also been used in the processing of minerals. In the mining industry, the reaction product of tall oil fatty acids and DETA can be used to separate silica firom phosphate ore by flotation... 

Any specimen preparation procedure leaves the surface in some state of roughness. It has been observed that the corrosion on poUshed specimens tends to increase in the first stages of a test, while on rough surfaces the rate decreases. Eventually, both specimens will reach a similar steady state. However, a large real surface area requires more inhibitor for inhibition than a polished one. Thus, surface preparation will affect the determination of the effective inhibitor concentration, particularly in constant inventory tests with a small liquid volume to surface area ratio. 

PHOSPHORIC ACID. H. P04- In laboratory tests, aqueous solutions of phosphoric acid (5-85%) were corrosive to 1100 alloy and the corrosion increased with concentration at ambient temperature. The rate attack was - 100 mpy at 5% and - 1200 mpy at 85% concentration. The action of pho horic acid can be reduced by the addition of inhibitors. Aqueous solutions containing phosphoric acid and chromium trioxide have been used as cleaning solutions and as surface preparation for painting of aluminum alloys. See also Ref (Dp. 139, (2)p. 566, (3)p, 132, (4) pp. 21. 29, 30. 74. 86. 138.139. (7) p. 143. 

Results from exposure corrosion testing show that aluminum surfaces prepared with a chromate conversion coating and a chromate-free primer perform much better than a chromate-free sol-gel type of conversion coating with the same chromate-free primer, " leading to the necessity for enriching the sol-gel coating with efficient inhibitors. 

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