Corrosion Policy Decision Making. Группа авторов

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Figure 2.16 Some weakness of the surface preparation. Paint application on rusted surface (left). Unsuitable abrasives and reuse of them several times (right). Weak surface preparation on weld lines (down).

Table 2.1 Adhesion of a common zinc phosphate epoxy primer on the steel surfaces prepared with several methods.

      In other research, the effect of different types of abrasives on steel preparation was investigated. Physical and chemical properties of tested abrasives are discussed in [17–19].

Properties of some abrasives are determined according to Table 2.2. In a series of tests, the author examined and compared the adhesion of a zinc phosphate epoxy primer with the same thickness on steel sheets that were prepared with these different abrasives. Results are summarized in Table 2.3.

      Often, the functional performance of abrasives, such as the effect on primer adhesion is very important. It affects the mechanical stability of the film, as well as its chemical resistance, especially when the film is exposed to humid and saline environments during service time. The author investigated the effect of a number of abrasives on cured film performance by doing several tests. For that, some samples were blasted by different abrasives. They were coated with the same paint, having nearly dry film thickness. Then they were tested in a humidity chamber according to ASTM D2247, and in a salt spray chamber according to ASTM B117 [20, 21].

      In these experiments, silica sand compared with different abrasives used for blasting surface. A noteworthy point about carbon steel samples prepared with copper slags was that their particles trapped in all samples. Slag particles were observed which could not washed out even by using air pressure (five bar pressure) and washing with solvent. However, for samples prepared with silica sand, leaving excess particles from the surface with compressed air were easily and completely removed from the surface. All samples were coated with the same paint layer with a similar dry film thickness.

Table 2.2 Properties of tested abrasives in blasting.

Table 2.3 Effect of abrasives on adhesion of primer at humid and salty environments.