Improved Accelerated Life Testing

The Navy continues to incur very high costs and lost service time due to unanticipated maintenance and repair or replacement of unreliable outboard sonar and other hardware on submarines, surface ships, minehunting systems and towed arrays. TRI/Austin will develop innovative new primer and potting compound materials to reduce water permeation, mitigate cathodic delamination failures, and to eliminate many hazardous materials. In addition to the development of these new second generation encapsulants for underwater connectors, improved and highly predictive ALT (accelerated life testing) procedures are required to certify long-term durability. Current PRO 20 approved products for the priming and potting of underwater electrical connectors and other components were developed many years ago. The original encapsulant materials were developed under specification (MIL-M-24041) which was written in 1971. Many of the originally developed primers contain hexavalent chromium (strontium chromate or zinc chromate) moreover; they also contain volatile organic compounds (VOCs) and hazardous air pollutants (HAPS). In addition, some of these polyurethane potting compounds contain ingredients, such as toluene diisocyanate (TDI) or 4,4'-methylene-bis (2-chloroaniline) (MOCA), which are potential carcinogens. Recently a new promising ALT procedure was developed at NUWC and its verification will be the subject of a round-robin study in the proposed effort.