Organic coatings, such as paint, are cost-effective barriers to corrosion, retarding the transfer of electrochemical charge from the corrosive solution to the metal beneath the coating. Autodeposition is a waterborne process utilizing a latex emulsion polymer, de-ionized water and proprietary ingredients. The part is immersed in the mildly acidic bath causing the release of iron ions and the deposit of the organic film on the surface of the metal. Powder coatings consist of a dry powder application to the surface of the object that is then heated, creating a smooth, continuous film over the part. A wide range of compounds are used in powder coatings, including acrylic, vinyl, epoxy, nylon, polyester and urethane.
Coatings are critical as the first line of defense against corrosion.
Equally important in corrosion prevention are component design and production processes. The guide exposes engineers to the different forming and joining processes so they can better understand how various factors impact corrosion, and it reviews important design issues including joint design and the openings required for post-fabrication application and draining of coatings. While all of the elements, from coating to design, offer potential solutions, only testing can validate their real-world impact. The guide discusses the critical nature of a good testing regimen in assessing the proper form and protection for individual parts. A proper test sequence begins with the appropriate selection of specimens.