The electrical resistance method has been employed to evaluate corrosion and corrosion inhibition in ethylene glycol-water solutions. Corrosion decreases the cross section of a metallic specimen with a subsequent increase in resistance. The extent of corrosion can then be determined from the change in resistance. The corrosion of iron, aluminum and cuprous metals is reported under varying test conditions of temperature, glycol concentrations and synthetic waters. The effect of some corrosion inhibitors upon these metals is illustrated.
Reasonably good correlation has been observed of the extent of corrosion measured by both resistance changes and by actual specimen weight loss. Pitting type of attack has been observed on many of the specimens; however, this attack has been uniformly distributed over the entire length of the specimen in practically all instances and has not prevented accurate determinations of corrosion rates. The concept of the use of precorroded metal surfaces in evaluating corrosion inhibitors has been enlarged upon. It has been observed that few corrosion inhibitors can stop effectively corrosion of a severely corroded metal specimen, whereas many corrosion inhibitors can maintain effectively the condition of an air-oxidized clean metal surface. 2.3.5
