Metal corrosion is a ubiquitous problem and generally costs an industrialized country several percent of its gross domestic product (GDP). For protection of aerospace aluminum alloys, chromate conversion has been most effective, but its deposition process uses Cr6+, which is a proven human carcinogen. Thus a chromium-free coating has long been desired. We were the first to propose, study, and demonstrate that zeolite coatings are extremely corrosion resistant in acids, bases, and pitting aggressive media, and could potentially serve as a chromium-free alternative.