Advanced SiC/SiC Composites by NITE Process

Cera-NITE®

Product information

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Gas Tightness (He Permeability)

He gas permeability of Ceramics and their composites

(Fig.5 : He gas permeability of Ceramics and their composites)

The highly dense, well crystallized SiC structure of Cera-NITE with low porosity and few cracks provides not only excellent mechanical properties and high thermal properties but presents outstanding gas tightness.

The He gas permeability test done at Hino laboratory, Hokkaido University provides excellent in He gas permeability as high as 1.0-10m2/s, which was even maintained even after the loading larger than the proportional limit strength.

In this figure, PG#1-#3 indicate the progress of processing during the pilot grade production at Ube Industries showing the improvement in He gas tightness more than 3 orders of magnitude from #1 to #3.

This He tightness was quite stable without significant degradation by minor plastic deformation caused by 10% higher loading than the proportional limit stress.

This is quite encouraging results showing the slow crack growth at the beginning of the elastic deformation and the insensitibity of gas tightness by this level of crack development.