The prevention of corrosion in packaging. III. Vapour‐phase inhibitors

Abstract

Of many compounds examined in vapour form in moisture‐laden air, a number will, in varying degrees, confer protection upon ferrous and some non‐ferrous metals when contained in the same enclosed space. Certain esters (e.g. n‐ and iso‐propyl benzoates, n‐butyl benzoates and methyl cinnamate) afford good protection to steel. Complete inhibition of the corrosion of steel and cast iron may be effected in moist air, even when heavily contaminated with sulphur dioxide, by certain amine carbonates, e.g. cyclohexylamine carbonate. These compounds also possess, in marked degree, the property of arresting the further corrosion of iron and steel surfaces that have already become rusted by exposure to moist polluted air.

Volatile corrosion inhibitors: a review

“…A weighed amount of inhibitor is heated at a constant temperature in a slow stream of oxygen-free nitrogen gas and the weight loss is measured. The volatilisation rate of the compound at various temperatures is obtained using the expression (Stroud and Vernon, 1952a):…”

Volatile inhibitors of atmospheric corrosion. III. Principles and methods of efficiency estimation

“…Gas-phase tests can be carried out at room temperature [10], but it occurs more frequently that the corresponding techniques involve either permanent or intermittent heating that accelerates corrosion, 2 and/or cooling of the cell or its parts that ensures vapor condensation [2,7,22]. The temperature variations are usually comparable with the possible daily variations and rarely exceed 35-40°C.…”

“…One of the first techniques for VCI efficiency estimation under vapor condensation conditions was suggested by Vernon [22]. According to this technique, the lower part of a cell with an aqueous VCI solution on the bottom is placed in a thermostat where a temperature of 35°C is maintained.…”

“…For example, a version of the same Vernon's method involves immersing cells with VCI solutions and metal specimens in a thermostat for only 8 hours a day [2,22]. In the case of VCIs that are not capable of metal protection by the azeotropic mechanism, the test results will reflect the "gross" volatility of inhibitors and the protective post-effect of the surface solutions that are formed on the metal when the specimens are kept in the cell before creating a temperature gradient in it.…”

Evaluation and Selection of Corrosion Inhibitors

“…Various accelerated procedures have been developed to simulate different conditions (e.g., tropical, marine, and industrial [11].) [26][27][28][29]. Observations are made after a predetermined time or number of cycles (for wet-dry tests).…”