| Popis: |
History of valve failure resulting from exudation of phosphate impregnations is reviewed, and the physical mechanisms leading to those failures are explained. A solution to exudation and abrasive crystal formation, developed through modification of phosphate polytypes, is introduced. Test data comparing un-altered and modified phosphate demonstrate that the newly developed material delays the onset of exudation by more than 50% under worst- case conditions. Weight gain vs. time data indicate that the new impregnation absorbs moisture more slowly, leading to the observed performance improvement. Additional improvement opportunities, to be tested in 2010, are discussed. Oxidation of Bushing Materials: Application of materials in the jet engine environment requires consideration of the long-term effects of mechanical, thermal, and chemical exposure on system reliability. Systems requiring mechanical translation or rotation combined with pressure isolation must utilize buffering materials that minimize wear to large components while also maximizing structural integrity through the lifetime of the system. The study of tribology focuses on the wear over time of material couples exposed to varying environments. |
