Evaluation of the protective properties of organic coatings by using tape and blistering tests

摘要

Bare stell panels coated with two alkyd paints were exposed to continuous immersion in a 3% NaCl solution. One- and two-layer systems with various dry film thickness were tested. Numerical values of delaminated area versus exposure time determined by blistering and tape tests were recorded. The results were compared with blistering kinetics determined for polyurethane (applied by spraying), and epoxide and alkyd electrocoats. It is assumed that the type test reveals the adhesion less caused by the accumulation of continuous water multilayers and by cathodic reactions at the metal/coating interface. Blistering is characterized by the initial and the undercutting induction times as well as initial and final blistering rates. These parameters allow to estimate partially the contributions of barrier, adhesive and inhibitive properties in the lifetime of the coating. Some recommendations to facilitate the evaluation of coatings by using tape and blistering tests are given.