# Re: [Vo]:melted alumina tube

```
I played with termite and stuff like that then I was young. ```
```
I
ignited termite with gunpowder and it melted steel.

On Tue, 17 Mar
2015 21:08:17 -0500, Jack Cole  wrote:
If it actually got hot enough
to ignite the thermite, that might melt the alumina. I was thinking Bob
said some time ago that it takes temps somewhere above 2000C to ignite
thermite. I haven't done the calculations for that yet.

On Tue, Mar
17, 2015 at 8:16 PM,  wrote:

Aluminium powder and Fe2O3 may give lots
of heat in short time a termite reaction.

Have you any calculations
about how much energy this reaction may release?

On Tue, 17 Mar 2015
18:26:24 -0400, Axil Axil  wrote:

followed by its rapid release can result in the delivery of a larger
amount of instantaneous power over a shorter period of time (although
the total energy is the same). Energy is typically stored within a
circuit of the device. What happens is based on the circuit of the
dimmer.

By releasing the stored energy over a very short interval (a
process that is called energy compression), a huge amount of peak power
can be delivered to a load. For example, if one joule of energy is
stored within a capacitor and then evenly released to a load over one
second, the peak power delivered to the load would only be 1 watt.
However, if all of the stored energy were released within one
microsecond, the peak power would be one megawatt, a million times
greater.

If the current rise is fast enough, the wire does not have
enough time to heat up, but the magnetic flux during the rise might be
huge.

On Tue, Mar 17, 2015 at 6:09 PM, David L. Babcock
wrote:

"Very sharp" -just means that the power is applied nearly
instantaneously. Not any more power, just whatever equals E2 /R. However
the temperature gradient would indeed be higher, so the wire would
expand sooner than the matrix around. If the matrix temperature rises
and falls a lot during a small part of a line cycle, stress might get
pretty high. But isn't the wire a near-zero expansion/temperature
material?

Ol' Bab -who was an engineer...

On 3/17/2015 4:02 PM, Axil
Axil wrote:
In these triac light dimmers, the rise/fall times are very
sharp maybe in the nanoseconds. That means that a lot of instantaneous
power is being feed into the heater wire as the power pulse starts when
the leading edge waveform is used.

On Tue, Mar 17, 2015 at 4:56 PM,
Axil Axil  wrote:

According to Jack, the reaction did not happen in the
fuel, but in the insolating layer. The fuel composition does not matter.
IMHP, what matters is the exact nature of the heater current.

On Tue,
Mar 17, 2015 at 4:38 PM, Robert Ellefson  wrote:

Jack,

Fantastic! I'm
really stoked to hear of your progress. I think your powder recipe
sounds very interesting, and I would love to know more about the details
of the reactants. It sounds like you've come up with a mixture which may
contain one or more key ingredients not yet identified as being of
primary significance to the high-gain modes of these systems.

If I
may fire away:

What size Fe2O3 and TiH2 grains were present?

Is
this mixture generally not hygroscopic, and therefore is curing the
reactor's sealant a simple matter as compared to LAH?
Are you tumbling
or milling these reactants, or performing any other notable processing
steps, prior to putting them into the reactors?

Thanks for sharing,
and keep up the great work!

-Bob

FROM: Jack Cole
[mailto:jcol...@gmail.com [6]]
SENT: Tuesday, March 17, 2015 1:08
PM
TO: vortex-l@eskimo.com [7]

SUBJECT: Re: [Vo]:melted alumina tube

Bob,

The input power was ~260W. I don't know what the R value of
the insulation is. I had the cell surrounded by high purity alumina
powder and covered with a thin sheet of ceramic insulation. I used
standard 120V AC 60hz with a triac type dimmer switch (chops the waves
starting at V=0). I'll have to check with the manufacturer to see what
the remaining 5% of the tube is. The heating element was Kanthal A1.
It's strange that the heating element was able to completely melt at
points. In the past, it has always failed before melting.

I was using
INCO type 255 nickel, TiH2, LiOh, KOH, aluminum powder, and Fe2O3. Good
idea on the small amount of fuel which should cause some localized
melting.

The fact that the fuel was a small diameter cylinder seems
to suggest that it was fully expanded in the tube and shrunk down.

Jack

On Tue, Mar 17, 2015 at 2:02 PM, Bob Cook  wrote:

Jack--

It looks like you had a pretty good reaction.

What was the input
power? What is the R value of the insulation on the outside of the
electric coils? What was the nature of the electrical input--frequency
etc? And what is the electrical heating element material? If you have an
acetylene torch, see if you can melt a piece of the tube that melted.

The tube may have had glass fibers incorporated in order to improve
strength. You indicated it was 95% pure. What was the other 5%?

What
was you fuel mixture? You may want to try a small fuel loading and see
if the same intense reaction happens--all else the same.

Try the
test with a iron core instead of a fuel load and determine if there is
an apparent magnetic field which would hold the iron core in position
when direct current is applied to the heating coil. An alternating
current would of course change the magnetic field and may make for null
reaction conditions.

Try 2 or 3 t/c's if you can--one inside and
two outside to get a measure of the temperature gradient along the tube.
Also another easy way to determine temperatures is the use of thermal
sticks on accessible surfaces. Welders use these to determine preheating
temperatures. They may provide a cheap temperature measure for you.

Keep it shielded--good luck.

Bob

----- Original Message -----

FROM: Jack Cole [9]

TO: vortex-l@eskimo.com [10]

SENT:
Tuesday, March 17, 2015 9:39 AM

SUBJECT: Re: [Vo]:melted alumina tube

To add a couple of more details. The agglomerated piece of material
is extremely hard. I tried to break it off with pliers, but it seemed
like it would take more force than to break the entire cell. The
resistance wire is extremely difficult to separate from the cell. I plan
to open the cell with a diamond blade later today to see if more can be
learned about what took place (e.g., evidence of melting on the inside
of tube). I was able to get one piece of the resistance wire pried from
the tube. There were indentations in the cell.

As a follow-up
experiment, I need to run it without the fuel to the same power levels
to see if the same effects occur.

On Tue, Mar 17, 2015 at 9:42 AM,
Jack Cole  wrote:

I had an interesting experiment yesterday. This was
my first time using a triac to regulate input power and sealing the tube
with a compression fitting. Unfortunately, my thermocouple failed.

Take a look at the alumina tube and the evidence for melting. The
furnace sealant which I coated it with completely melted and
agglomerated to the bottom of the cell (also appears to be mixed with
melted alumina).

[12]

The tube was purchased from China and is purportedly 95% pure.
It was supposed to have a continuous operating temperature of 1500C.

Any opinions?

Jack

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