I cannot claim to be a ceramic cement expert. Some cements are multiphase - they include a chemical bond to start, a glass phase that melts and bonds at higher temperature, and a ceramic forming phase that kicks in at at higher temperature still. Most are not intended to form a hermetic seal - they are meant to be primarily mechanical. It is the glass phase that is most useful in hermetic bonding. It may be that the R-919 was not properly cured or had an inadequate glass phase. I believe that Ryan just let it air dry for a few hours and then started heating. It could have blown through before the seal was heated to the glass vitreous phase. It should have been cured to the vitreous phase at least before heating the whole thing.
The next try will probably be with a Schott glass frit paste - all glass, designed for hermetic sealing. The glass will be melted in place at the seal before heating the whole reactor with the fuel. On Thu, Jan 1, 2015 at 6:33 PM, Jack Cole <jcol...@gmail.com> wrote: > According to the specs, it requires 24 hours to cure at room temperature. > Do you think it is not hermetic because it's not capable of that, or > because it wasn't cured? > > On Thu, Jan 1, 2015 at 2:23 PM, Bob Higgins <rj.bob.higg...@gmail.com> > wrote: > >> The first attempt did use a Cotronics Resbond 919, I think. These >> alumina cements are not hermetic. That's why glass frit seals are being >> examined - they are hermetic. >> >>
