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.
On Thu, Jan 1, 2015 at 1:15 PM, Jack Cole <jcol...@gmail.com> wrote: > Hi Bob, > > I wonder about this Thermeez Ceramic putty. > > http://www.cotronics.com/catalog/51%20%20%207020%20%20901.pdf > > It cures at room temperature, so that removes the issue of hydrogen off > gassing during curing. What I don't know is if it will be effective > against holding in the hydrogen. I emailed the company and hopefully they > can provide some guidance. > > > On Thu, Jan 1, 2015 at 1:41 PM, Bob Higgins <rj.bob.higg...@gmail.com> > wrote: > >> Parkhomov starts with a 10mm OD alumina tube with a 5mm ID bore (so the >> wall of the tube is 2.5mm thick). He plugs both ends with an alumina rod >> and "cement" with the fuel inside. He hasn't said what "cement" he uses to >> hermetically seal the plugs in the tubing, but he does say that it is a >> hard 3-day process. After the hermetic plugged tube assembly is made he >> winds this tube directly with a nichrome wire coil and paints it all over >> with a thick alumina cement. MFMP has asked Parkhomov what he used for >> cement and what his hermetic sealing process was and he has not yet >> responded. >> >> In the mean time MFMP is discussing using a high temperature glass frit >> seal for the plug. One end is already molded and fired closed - the tube >> was purchased that way. So the fuel will be added, then an alumina wool >> plug near the seal end, then the alumina plug painted with a glass frit >> paste having a resulting thermal expansion matched to alumina. Then the >> fuel end will be cooled while the seal end is heated with a torch to melt >> the seal glass and form a hermetic seal. This is the MFMP "reaction tube", >> about 0.25" OD. >> >> The dogbone heater coil is wrapped around another alumina tube into which >> the reaction tube can be inserted (slightly larger than 0.25" ID). This >> allows the reaction tube to be replaced without having to wind a new heater >> coil and overmold it for every experiment. In MFMP testing, the previously >> fueled and sealed reactor tube is inserted into a dogbone heater tube that >> has the coil wrapped and enclosed in molded alumina cement. Power is >> applied to the dogbone heater coil which heats the reactor tube that was >> slipped inside. >> >> Bob >> >> On Thu, Jan 1, 2015 at 12:24 PM, Bob Cook <frobertc...@hotmail.com> >> wrote: >> >>> Bob-- >>> >>> How does Parkhomov get a uniform thickness of alumina cement, whatever >>> that is, between the 2.5mm alumina tube (reactor tube in previous >>> correspondence) and the alumina dogbone with the electrical heater wires? >>> It may be that I do not understand the physical arrangement of the various >>> alumina components of the Parkhomov experiment. >>> >>> Bob >>> >> >
