Chlorotrifluoroethylene oligomer based nonflammable hydraulic fluid. 1 Fluid, additive, and elastomer development

A chlorotrifluoroethylene (CTFE) based nonflammable hydraulic fluid for use in the −54 °C to 175 °C temperature range has been developed for use in future aircraft and armoured land vehicles to reduce fire losses and improve survivability. The desired flammability, chemical, and physical properties of a non- flammable hydraulic fluid were defined in the 1970s and extensive screening tests were performed to determine the best candidate nonflammable hydraulic fluid basestock. CTFE was selected because it had the best overall properties of all the candidates investigated. Structurelproperty correlation studies were conducted better to understand the behaviour capabilities and limitations of the CTFE basestock. Extensive research and development have been per- formed to develop soluble, effective antiwear and antirust additives to improve some of the critical properties of CTFE. A successful formulation utilising a stabilised zinc, containing corrosion inhibitor and a sulphonamide antiwear additive, has been developed which meets all temperature, lubricity, compatibility, and thermal stability requirements. Research was concurrently conducted to develop elastomers and seals compatible with the CTFE fluid. Several materials have been developed which are usable in somewhat limited applications and Viton GLT has been found to be successful for wide temperature range applications. This paper also discusses toxicity studies and results, environmental effects, future plans and applications, and the current military specification, MIL-H-53119.