Ceramics, including aluminas, that are proton conductors are intentionally doped in the grains with metals designed to provide a chemical transport of hydrogen ions through the body, primarily at the grain boundaries (as I understand it). The CoorsTek AD-998 alumina is not designed for proton transport, but there may be some small residual rate. A leak through pores would be a gross leak for hydrogen, particularly if the pressure really turns out to approach 100 bar.
He leak testing is a standard way for evaluation of hermeticity, but the test apparatus is usually fairly specific to the package being tested. In this case, the reaction tube is fairly large and may need a custom system designed to do He leak testing. Bob On Thu, Jan 1, 2015 at 7:27 PM, Bob Cook <frobertc...@hotmail.com> wrote: > I would say the surrounding alumina is the seal that is important, and I > do not think it is an hermetic seal. Its porosity allows some leakage, > particularly at the temperatures of 1000 degrees C. Thermal stresses in > non-ductile materials are bad when it comes to hermetic sealing. Glass > which flows is somewhat better. If one wants real hermetic sealing, he > should test it at temperature with He for leakage. > > Bob >
