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Mon Dec 01 17:43:41 1997 Corrected notes
(1) Aluminum burns hot. (The probable source of excess heat observed
is likely from oxidation of Al.) Its heat of combustion is 399,000
cal/g mole, or 7200,00 BTU/lb mole. With atomic weight of 26.98154
the energy is 14,800 cal/g. A 709.5 cm^2 sheet of Al foil used for
electrode material weighs 2.91 g. That is 4.10x10^-2 g/cm^2 or about
607 cal/cm^2 consumed. It was not unusual in an hour for about 1/2 of
the foil to be consumed on each of two electrodes, each about 2 cm^2
in area, so the heat generated would be about 1200 Cal. - enough Al
consumption to account for your 2% ou reading? (Why the heck is a
"hydrogen economy" such a big deal - we should got to the "Al
economy". Besides great availability and compactness, it burns
without air pollution!) Some electrolytes produced a white granular
powder at the bottom of the cell which needs to be explored further.
Might have been blown off the surface by cavitation shock. Some
electrolytes, those not so alkiline, like baking soda, appear to
dissolve the foil.
(2) The Al2O3 layer conducts electrically, so the insulator is
something else, or it is an Al2O3 layer that is thicker due to
conditioning. To test I simply measured the resistance of the Al
elecrtodes. There was no noticeable resistance, even though the
current has to go through the Al2O3 layer twice to get through the
electrode.
(3) The fact plain H2O alone doesn't create the insulating layer
suggests Al2O3 is not the insulating layer. Some electrolyte appears
necessary. Alum didn't work. Baking soda didn't work.
(4) The insulating layer acts as a diode (with a bypass resistor in
parallel).
(5) The two opposing layers conditioned on opposing electrodes by AC
make the cell act as a capacitor.
(6) The insulating layer in some cases works to over 1000 V peak.
(7) There is a phase shift that builds as the electrode is
conditioned. This phase shift is due to the induced capacitance due
to the opposing diode effect. The phase shift is critical to measure
when determining power input because the true power input is not as
large as otherwise measured unless a true integral of I*V is determined.
(8) Successful electrolytes tested on Al electrodes contained either
Li or Na salts and were alkaline.
(9) Na salts can condition the Zr electrode. No Li test yet made on
the Zr electrode (by me anyway).
(10) Al conditioned with sodium metasilacate (N2SiO3) has a very good
insulating coating, and few active spots, and they tend to be in the
center of the electrode - indicating the edges are quickly
conditioned. The active spots turned in to holes of active spots
eating away the outer rim. Very interesting possibilities. This was
one of the combinations that produced white granular material at the
bottom of the cell.
(11) Zr appeared ou during initial conditioning.
(12) Upon mesuring the resistance of the films on various Al and Zr
electrodes it was noted that the Zr electrodes had a very strong
insulator (infinite) not easily poked through with the probes as the
Al insulator was.
(13) Upon looking at the Al electrodes under a microscope, it
appeared the active spots were shiney crystals on the rim of, or on
raised areas in, holes in the surface insulating layer about 20 to 60
microns wide, and about 5 microns deep. The crystals were from 1 to
20 microns across and often in close groups of 3 or 4. The normal
unconditioned foil was shiney and had 1 micron grooves with 1 micron
elevated ridges. There were roughly 1 micron bright spots atop the
ridges in the unconditioned foil. The conditioned foil looked white
to the eye but dark and cratered under the microscope, with no ridges
visible. The diameter of the visible area under the microscope was
1.1 mm.
(14) A strong magnetic field (but under .5 T) appeared to cause
active spots to form on the back side of the electrodes. This will
have to be examined more carefully to see if (a) the effect is real
and (b) if the spots simply bored through the foil from the other
side (faster.) The effect was not darmatic but seemed very reliably
consitant the few times it was tried.
(15) During the conditioning process the eventually successful
electrodes glow a blue or blue green.
(16) Electrodes made of solder did not glow or form underwater sparks
or a non-conductive coating but produced a lot of bubbles and heat.
The heat probably due to the high conductivity of the electrodes, but
should be looked at again carefully.
(17) When a fullwave bridge was inserted in a circuit containing
glowing electrodes, the glow went with the anode. This indicates the
glow is probably related to oxidation of the Al. Conjecture follows:
More carefull experimentation on this needs to be done with respect
to sparks. It could be that both phases are required in building a
good insulator, i.e. both the anions and cations are involved in
building the surface insulator. Once built, both cycles may be
necessary to sustain the insulating surface as well, even though
sparks may work briefly in a DC environment.
(18) As the sparks begin the glow subsides. A sign that the
conditioning is complete and only a few holes remain in the surface
for conductivity. This is an indication that bubble formation and
closeoff probably limits the conduction time for an active spot. This
jives with the fact that there are bright crystals (probably
conductive) visible on the surface. Need to test conductivity of
bright spots with fine needle. Would be useful to do SIMS on the
spots to see if they are AL or an alloy or what.
(19) Alum, K2Al2(SO4)4*34(H2O), molecular weight of 808.57, (the new
element K replaces Li or Na) did not work well as an electrolyte.
Need to try lower concentrations. Too conductive. Should get some K
in the electolyte somehow. KNO3 not so hot in some tests but nothing
conclusive there either. KOH with LiOH is the obvious thing to try.
(20) Some candidates for the surface film resulting from Li based
"conditioning" of Al electrodes are spodumene (LiAlSi2O6) or petalite
(LiAlSi4O10). I think spodumene is the likely candidate for
formation from a Na2SiO3 electrolyte, which seemed to create the most
effective insulator.
(21) Once conditioning is complete and the cell is sparking, ramming
the voltage up to over 1000 V rms creates more spots which remain
when the voltage is dropped back to the more normal 400-500 V rms
range. It is a form of superconditioning.
(22) Red Devil household lye, NaOH, mol wt 40.01, 0.26 g/l along
with Al foil works great, but takes a while to condition. This is a
good formula for amateurs, but the voltages are a bit high!
(23) Dishwasing detergent, a few granules to 500 ml also works fine,
and permits (requires) use of much higher voltages.
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Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
