I think the failure was caused by a brittle fracture of the alumina tube due to thermal stresses, internal micro stresses caused by micro bubble formation and resulting embrittlement.
Bob Sent from Windows Mail From: Bob Higgins Sent: Friday, February 6, 2015 1:00 PM To: [email protected] Ryan Hunt reports that the failure mode was NOT the compression fitting giving way under pressure - the fitting remained intact. This experiment was of the "easier Parkhomov" design, posted previously where the seal was made with a compression fitting, in this case with the use of a soft aluminum ferrule at the suggestion of Alan Goldwater. Alan's tests suggested the compression fitting would hold and it did! Using the compression fitting is a real win because it completely avoids the problematic sealing of the ends with cement while providing an opportunity to instrument the reaction vessel. When this failure occurred, it appeared to be a raw ceramic body failure. This could easily have come from too much pressure coming from a too large charge of LiAlH4 for the vacant volume inside the apparatus. MFMP will extract that volume information and relate it to the weight of LiAlH4 that was added, as being a benchmark for too much LiAlH4. The tube used was 1/4" OD, but at the moment, I am not sure if it was a 4mm ID tube or a 1/8" ID tube. The Parkhomov tube had an ID of half of its OD. Bob Higgins On Fri, Feb 6, 2015 at 11:39 AM, MarkI-ZeroPoint <[email protected]> wrote: At 2:29/2:30 into the short segment posted by Craig, it looks like the right-side end-plug, or whatever is sticking out that end, blows out. And I use that term specifically since one also sees some hint of a pressure release. Whether that release is at an appropriate level is apparently debatable... -mark iverson
