CB Sites--
Check out the following for LiAlH4 decomposition:
http://rspa.royalsocietypublishing.org/content/royprsa/211/1106/335.full.pdf
Mark Jurich provided a nice reference list on the properties of LiAlH4
yesterday, Saturday, January 03, 2015 11:56 AM nere on Vortex-l. The one cited
above is from his list.
Bob
----- Original Message -----
From: CB Sites
To: vortex-l
Sent: Saturday, January 03, 2015 10:04 PM
Subject: Re: [Vo]:Ceramic-to-metal hermetic bonding
You know Axil, maybe they are based on the internal pressure estimates I've
read here. When the MFMP finally had the pressure transducer stabilized they
had 100psi which decreased linearly to 0 after power off. A redo of that
experiment would be worth doing just to get the kinks out of the pressure
gauge. Then you might see the disassociation of LiAlH4 to Li and H in the
pressure change. As another vortexian mentioned, I don't think that has ever
been published. So knowing PV=nRT the value 'n' can be deduced or the expected
value of P can be deduced with temp as some have already done. Given a
temperature goal, and perhaps knowing the strength of the contain these can be
designed into the experiment. So instead of worrying about seals, just design
a tube that can contain hydrogen gas at 1400C and be loaded with fuel under a
vacuum to maintain purity of the reactants.
On Sat, Jan 3, 2015 at 11:29 PM, Axil Axil <janap...@gmail.com> wrote:
I think that MFMP is concerned about melting or exploding the core.
On Sat, Jan 3, 2015 at 11:07 PM, CB Sites <cbsit...@gmail.com> wrote:
I agree with you Bob. Getting a good seal will be the challenge of this
experiment. I've seen a few electron micrographs of hydrogen is Si and other
metals and it is amazing how deep H will migrate into a lattice. Jones Benne
points to the S-bond.com. It will take something more than that to seal this
structure at the high temps, high pressure and embrittlement from hydrogen gas
in this experiment. Knowing the pressure and core temp is a noble cause, but
until replication is done, do we know enough about the phenomena to pursue
those experiments?
On Sat, Jan 3, 2015 at 6:40 PM, Bob Cook <frobertc...@hotmail.com> wrote:
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.
