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The effect of some pyrazoline derivatives as inhibitors on the dissolution of A1 in 2 mol.L−1 HC1 has been studied by weight‐loss, galvanostatic polarization, polarographic and scanning electron microscopy methods. Additions of Cu2+ Co2+ or Ni2+ ions increases the efficiency of the inhibitors.

Cations such as Cu2+, Co2+, Ni2+, Zn2+ or Ba2+ increases the corrosion rate of aluminium in 2 mol.L−1 HCI. This corrosion rate could be decreased by the addition of inhibitors which may form complexes with the cation used. Measurements of the corrosion rate of aluminium in 2 mol.L−1 HCI with and without addition of aliphatic substituted P‐hydroxy acetophenone hydrazone derivatives (10−4 — 10−5 mol.L−1) has been studied by weight loss and galvanostatic polarization methods. The same inhibition efficiency of the compounds has been found using either of the methods. In general, the efficiency of the inhibitors increases with an increase in aliphatic chain length. Activation energies in the presence and in the absence of inhibitors has been evaluated. Galvanostatic polarization data indicate that all these compounds are predominantly cathodic inhibitors. The rate of corrosion increases with increase in temperature together with a decrease in protection efficiency indicating that inhibition occurs through adsorption of the additives.

The inhibition of aluminium corrosion in solutions of hydrochloric acid or sodium hydroxide has been studied using weight‐loss and hydrogen evolution methods. Benzoic acid and its derivatives inhibit acidic and alkaline corrosion effectively. The efficiency of inhibitors increases in the order: benzamide < benzaldehyde < acetophenone < benzoic acid < benzophenone (100%). The inhibition efficiency of acid anhydrides follows the sequence: pyromellitic > naphthalic > trimellitic. Inhibition takes place through adsorption by a one‐step process with greater efficiency in alkaline than in acidic methanolic solutions.

Inhibition of carboxylic acids of aluminium corrosion in hydrochloric acid and sodium hydroxide solutions has been studied using weight‐loss and hydrogen evolution methods. The order of inhibition action of aromatic acids depends on the number and position of the carboxylic groups and the other substituents in the benzene ring. Increase of the chain length increases the inhibiting power of aliphatic acids. The inhibition efficiency in NaOH is higher than that in HCI solutions. The action of inhibition was discussed in terms of the chemical structure of the inhibitors.

The efficiency of some 2‐heterocarboxaldehyde‐2′‐pyridyl‐hydrazones as inhibitors for the acid dissolution of Al was studied by mass loss, hydrogen evolution and polarization measurement techniques. The corrosion rate was measured in 2M HCI at different temperature and concentrations; maximum percentage protection (85%) was obtained at 103M for the compound containing oxygen atom. The activation energies were calculated for all the additives used. The rate constant decreases as the inhibition efficiency increases. The results show that the studied materials influencing both the cathodic and anodic process. The mechanism of inhibition was proposed on the basis of the formation of a protective monolayer by the inhibitors molecules on the metal surface according to Langmuir isotherm.

Corrosion inhibitors are widely used in industry, although in many cases their surface chemistry is not well understood. Several nitrogen‐containing organic compounds have been used as corrosion inhibitors. Corrosion inhibition is a surface process which involves the specific adsorption of inhibitors on the metal surface. The extent of inhibition of metallic corrosion may depend on the nature of the metal surface and extent of adsorption of the inhibitor. The type of interaction of the inhibitor on the metal surface during corrosion has been deduced from its adsorption characteristics.

To investigate the inhibiting effect of the cationic surfactant cetyl trimethylammonium chloride (CTAC) on aluminum (Al).

Pure aluminum rods were immersed in hydrochloric acid (HCl) and sodium hydroxide (NaOH) solutions for weight‐loss tests and potentiostatic polarization measurements.

The inhibition action depends on the concentration of the inhibitor, the concentration of the corrosive media, and the temperature. The inhibition efficiency in NaOH was higher than that in HCl solutions. In both acidic and basic media, the increase in temperature resulted in a decrease of the inhibition efficiency and a decrease in the degree of surface coverage. The results were indicative of increased aluminum dissolution with increasing temperature. It was found that adsorption of CTAC on the aluminum surface follows Temkin's isotherm in HCl and Langmuir's isotherm in NaOH.

Clarifies the effects of concentration and temperature on the inhibition efficiency of a cationic surfactant on aluminum.