Re: [Vo]:melted alumina tube

```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, <torulf.gr...@bredband.net> 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 <janap...@gmail.com> wrote:
>
>  Steady accumulation of energy 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 <olb...@gmail.com>
> 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 <janap...@gmail.com> 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 <vortex-h...@e2ke.com>
>>> 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]
>>>> *Sent:* Tuesday, March 17, 2015 1:08 PM
>>>> *To:* vortex-l@eskimo.com
>>>>
>>>> *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 <frobertc...@hotmail.com>
>>>> 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 <jcol...@gmail.com>
>>>>
>>>> *To:* vortex-l@eskimo.com
>>>>
>>>> *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 <jcol...@gmail.com> 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).
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> 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
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>
>>
>>  ------------------------------
>>    <http://www.avast.com/>
>>
>> This email has been checked for viruses by Avast antivirus software.
>> www.avast.com
>>
>
```