Jones-- Unless the thermal expansion of the alumina body is matched to the expansion of the Stainless Steel sleeve, it will be very hard to maintain a seal. The thermal stresses will become very high at the interface of the two materials. I think that the pressure changes seen in the recent MFMP test were due to thermal expansion acoustic emissions upon each increase in temperature. This emission caused the pressure sensor to spike. A sonic acoustic emission monitor would be valuable to deduce where the strain is and its intensity as a function of heating, if good sealing of the connection is necessary. I am not sure the objectives of the test required such sealing and pressure containment.
(Acoustic emission monitoring is an old technique to look for micro cracking in fission reactor equipment that happens during thermal transients. Its quite sensitive and has/had been resisted by reactor vessel manufacturers, because it was so good for identifying defects in their forgings that other wise might not be discovered.) Bob ----- Original Message ----- From: Jones Beene To: vortex-l@eskimo.com Sent: Saturday, January 03, 2015 1:49 PM Subject: [Vo]:Ceramic-to-metal hermetic bonding It is possible to bond alumina, such as a modified dogbone reactor directly to stainless tubing, using the proprietary S-bond alloy : http://www.s-bond.com/blog/2011/04/04/ceramic-metal-bonding-part-one/ The advantage would be allowing a permanent fill port for hydrogen, along with a pressure gauge, and other feed-thru accommodations which are more easily ported into metal then into ceramic. The design problem would be in keeping this metal part of the reactor cooler than the rest of the reactor - and the simple solution for that is to add a long ceramic extension tube to the dogbone, which extension is not powered and it can be as long as the reactor itself with a decreasing temperature gradient, then to add the stainless plumbing to the far end of the ceramic extension tube using S-bond. This keeps the heated segment spatially removed from the stainless. There would be a hot-end and a cold-end, and the entire unit would be much longer. For any dogbone device to move towards commercialization, far more control must be implemented, including fuel availability and pressure - and this means adding hydrogen from a tank at a controlled pressure. A ceramic to metal bond is one way to do that. I am assuming that hydrogen is the only consumable, at least until testing from Parkhomov shows otherwise.
