Abstract: This article introduced the major molding processes of polytetrafluoroethylene (PTFE) sealing rings used for the one-way valve of oxygen systems in the space engine. The reasons for the occurrence of cracks in the PTFE seal ring were analyzed in terms of the macroscopic aspect and microscopic morphology. The results indicated that the internal gaps within PTFE seal rings could be effectively eliminated when being prepared by use of sieved PTFE powder under an exhaust condition during the cold-pressing per-molding. The tensile properties of PTFE seal rings were improved significantly as a result of this modification, and hence the reliability of PTFE seal rings was enhanced to meet the requirement of aerospace areas for the one-way valve of oxygen systems.

Key words: oxygen system, one-way valve, polytetrafluoroethylene, sealing ring, cracks