论文部分内容阅读
The salt spray laboratory corrosion test was introduced as an ASTM standard more than 100 years ago,and even today it is the most commonly performed method.The people who developed the standard recognized that the test did not accurately replicate real world corrosion in most cases,but they considered the test critical because it enabled repeatable and reproducible results.This made it a critical quality control test in the automotive and other industries.The method was also adaptable for a variety of metallic substrates by acidifying the salt solution.Wet and dry cyclic tests were developed for better replication of real world corrosion.This innovation allowed more accurate differentiation of relative performance levels among materials and protective coatings,but these tests did not supplant the traditional salt spray test in popularity.The likely reason is that the wet and dry cyclic tests were not repeatable or reproducible,so they were not reliable for use in a quality control environment.During the last 25 years,the automotive industry has developed wet and dry cyclic tests with modernized requirements that allow them to accurately replicate real world corrosion mechanisms and appearance.Better test chamber technology and test performance requirements have also significantly improved the reproducibility of these tests,so they can be used for material development and in quality control applications.This presentation will review these developments and provide some data to illustrate the importance of these new test performance requirements.