ELIMINATION, REDUCTION OF HEXAVALENT CHROMIUM COMPOUNDS FROM AIRCRAFT ADHESIVE BONDING PROCESSES

摘要

Bond primers are applied in critical structural areas of aircraft to maximize adhesive performance at the bond-line. Additionally, the current class of DoD-approved primers contains hexavalent chromium (Cr~(+6)) to prevent substrate corrosion and subsequent bond failure; however, hexavalent chromium is a human carcinogen and a hazardous air pollutant (HAP) with strict EPA [1,2,3] and OSHA [4] regulations. In addition to the regulations, hexavalent chromium-containing materials pose significant hazardous waste disposal costs and necessitate costly controls to prevent human exposure during application and removal.rnAt least two bond primers containing no hexavalent chromium (3M's EW 5000AS and Cytec's BR 6700-1) are commercially available. Neither of the primers has been thoroughly characterized for high risk aircraft applications. Through the Navy's Aircraft Equipment Reliability and Maintainability Improvement Program (AERMIP), NAVAIR tested these non-hexavalent chromated bond primers against a hexavalent chromium control (Cytec's BR 6747-1). Specifically, the primers were evaluated in floating roller peel, single lap shear and wedged crack extension testing. These screening tests were completed at three Navy installations (North Island, Jacksonville and Patuxent River). Comparable performance of the non-hexavalent chromium bond primers to the hexavalent chromium primer would lead to a more thorough laboratory evaluation and subsequent demonstration/validation on Naval aircraft platforms.