Abstract:

The gas tightness of the three-dimensional (3-D) braided preform as sealing material was studied. By cimbining actual situations, the braided sealing rings of three structures with fiber volume fraction of 50% were prepared from quartz fiber, which had 3-D 4-directional structure, 3-D 5-directional structure and 2-D core-spun structure. The gas leaking experiment was carried out to measure the gas tightness thereof to obtain the gas volume flows of the three kinds of braided fabrics on different pressure and at different compression ratio, and the gas permeability of the three kinds of braided fabrics at each stage was calculated, The Results show that all the three braided sealing rings reach the sealing requirements, and the gas permeability gradually increases with the increase of the pressure difference, but decreases with the increase of compression ratio. Moreover, the gas permeability of the 3-D braided sealing rings is much better than that of the 2-D core fabric, and the average gas permeability is 35.5% of the 2-D core-spun fabric. The 3-D 4-directional braided annular thermal seal ring shows the lowest gas permeability and exhibit the base gas tightness.

Key words: sialing ring, 3-D braided structure, gas permeability, gas tightness