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 <[email protected]> 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 <[email protected]> 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 >> >
