An analysis of the DSC data in the Herrit-Jones paper, page 1

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Topic started on 4-12-2010 @ 01:05 PM by pteridine

A bit of background is in order for those not familiar with the techniques under discussion. There are various configuration and electronic options for DSC instruments. Jones uses a NETZSCH 404C [for details, see www.netzsch-thermal-analysis.com...]. The way DSC works is that a covered sample pan with the sample and an empty sample pan and lid are placed in a temperature controlled furnace. Both are heated at some rate, in this case 10 C/ minute, and heat flow is measured as the temperature changes. Processes that release heat are called exothermic and processes that require heat are called endothermic. There are different ways to view the trace; some traces have exotherms show as peaks and endotherms show as valleys. Jones claims such. With the electronics in this configuration, any heat generated, such as combustion, will appear as a peak. Any heat used, such as that for melting a material or evaporating water, will appear as a valley. Careful calibration of the instrument allows for the heat flows to be measured. If the weight of the sample is known, the energy per unit mass can be calculated. What the instrument does not do is measure the temperature of the reaction. The temperature shown on the x-axis is the furnace temperature, not the sample temperature, so there is no way of directly measuring flame temperature. Jones does not state if he used pans with lids or open pans [a peer review would have noted this and had him be specific]. He does run the DSC in air rather than under argon so he can’t determine if any heat generated was from a reaction or combustion. In retrospect, he realizes that he erred when he did this and adds weasel words on page 27 of his paper; “As this test was done in air it is possible that some of the enhancement of energy output may have come from air oxidation of the organic component.” The phrase “air oxidation of the organic component” is Jones-Speak for combustion. This means that it could have burned to make the heat and there is no way to tell how much heat was made by combustion [“air oxidation of the organic component”] and how much was made by a reaction of some sort.
The thermite reaction is more complex than most imagine. For the purposes of this discussion we will allow that it is simply the reduction of a metal oxide, in this case iron oxide, with elemental aluminum. We will also use Jones statement of the theoretical maximum of 3.9 kJ/g [page 27]. This theoretical maximum applies to all thermite reactions, regardless of particle size. Not all thermite reactions may give this value; thermites with larger particles are claimed to produce a few percent less energy, but the thermite reaction has 3.9 kJ/g as its upper limit regardless of particle size. What does change with particle size is the rate of reaction. The smaller the particles are, the faster they react and the faster the energy comes out. This has to do with relative surface areas and diffusion and is the basis for the advantages of nano-particulate thermite.
Now for the energetics shown in Fig 30 on page 27. We will be concerned with the blue bars; energy per unit mass in kilojoules per gram [kJ/g]. In this figure, the energies of various nitrogenous explosives HMX, TNT, and TATB are compared with thermite and the four chips analyzed by the DSC.
Based on this figure, we may approximate the following theoretical and measured energies:

Not measured in this experiment:
HMX = 5.5 kJ/g
TNT = 4.5 kJ/g
TATB = 4.1kJ/g
Thermite = 3.9 kJ/g
Measured in this experiment:
Chip #1 = 1.5 kJ/g
Chip #2 = 2.5 kJ/g
Chip #3 = 7.5 kJ/g
Chip #4 = 5.9 kJ/g

The first thing we notice is the wide disparity of values for the “highly engineered” material. This should raise doubts as to sample collection and preparation and even if the materials are the same thing. By other analyses, they appear similar.
Now we note that two of the chips, #3 and #4 have far more energy than if they were 100% thermite. They also have more energy than any of the high explosives or any combination of thermite and any high explosive as a composite. Arithmetically, if we have a 50:50 mix of thermite and HMX we should have an energy of about 4.7 kJ/g -- below that of chips #3 and #4. How can this be?
To explain this, we must understand what is being measured and how. The explosives and thermite have, internal to them, their own oxidants. We include their oxygen in the weight we measured. If we measure heat from a burning hydrocarbon, for example, we DON’T include the weight of the oxygen in the air we use to burn it. Candle wax burning in air has about 10 times the energy/gram of thermite using this convention. What does this mean? It means that some, if not all, of the energy from the red chips is due to burning of the carbonaceous paint matrix in air.
Jones is vague about this problem and says on p27. “We suggest that the organic material in evidence in the red/gray chips is also highly energetic, most likely producing gas to provide explosive pressure.” What might that energetic material be? Jones has no clue. His team lacks the chemical knowledge to postulate a reasonable composition. It has no nitrogen, so it is not one of the explosives shown. It is energetic when burning in air. So is candle wax. Volatilized, it will produce gas but it does not seem to be otherwise energetic. How can this problem be resolved? What experiment must be done to show the possibility of thermite or some composite?
As I have stated above, thermite and explosives have their own oxidants built in. burning hydrocarbons do not. How can Jones discriminate between explosives, thermite and plain old burning paint?
He can re-run the DSC under an argon atmosphere. What a simple and elegant solution. Under argon, all the energy coming out will be from the thermite and its energetic additives. If there is no energy coming out, there is no thermite and all those contortions and obfuscations are for naught. Why wouldn’t Jones do this obvious experiment? Maybe he did and didn’t like the results.

reply posted on 4-12-2010 @ 01:35 PM by jprophet420

He can re-run the DSC under an argon atmosphere. What a simple and elegant solution.

What an elegant idea for *anybody* who is interested in the truth.

Maybe debunkers ran the experiment as you suggested and they just didn't like the results *they* got.

reply posted on 4-12-2010 @ 01:58 PM by turbofan

reply to post by pteridine

Is this your complete submission?

I notice you didn't show your work for specific energy release of the elements found which is what your entire
argument is based upon.

IE: You must show that combustion of certain elements created a significant amount of heat above and
beyond such mixtures as basic conventional thermite, etc.

Do you plan to include any sort of support, links, science for your claims, or shall we work with your initial
post?

Let me know and I'll begin the reply.

edit on 4-12-2010 by turbofan because: (no reason given)

reply posted on 4-12-2010 @ 02:05 PM by NIcon

The first thing we notice is the wide disparity of values for the “highly engineered” material. This should raise doubts as to sample collection and preparation and even if the materials are the same thing. By other analyses, they appear similar.

The first thing I noticed was a not careful reading of the paper:

"Proceeding from the smallest to largest peaks, the yields are estimated to be approximately 1.5, 3, 6 and 7.5 kJ/g respectively. Variations in peak height as well as yield estimates are not surprising, since the mass used to determine the scale of the signal,shown in the DSC traces, included the mass of the gray layer. The gray layer was found to consist mostly of iron oxide so that it probably does not contribute to the exotherm,and yet this layer varies greatly in mass from chip to chip."

So the grams of the gray layers was included in the calculations, the gray layers aren't affected and the gray layers (grams) varied greatly between the samples. Thus the variations in the numbers. No surprise there.

it is simply the reduction of a metal oxide, in this case iron oxide, with elemental aluminum.

Secondly, I notice you make the case for them quite well, as their conclusion is based upon iron oxide they found in the red layer was reduced to iron. Or as they put in their paper:

"A conventional quantitative analysis routine was used to estimate the elemental contents. In the case of this iron-rich spheroid, the iron content exceeds the oxygen content by approximately a factor of two, so substantial elemental iron must be present. This result was repeated in other iron-rich spheroids in the post-DSC sample as well as in spots in the residue which did not form into spheres. Spheroids were observed with Fe:O ratios up to approximately 4:1. Other iron-rich spheres were found in the post-DSC residue which contained iron along with aluminum and oxygen."

I fail to see how a 4 to 1 or a 2 to 1 ratio can somehow be mistaken for a 2 to 3 ratio of your typical iron oxide. There should be equal or greater amounts of oxygen as compared to amounts of iron if there is no elemental iron present. Unless someone can show me a formula for an iron oxide that has more iron atoms than oxygen atoms.

So what I'm looking for is proof they did not find elemental aluminum and they did not find elemental iron because it really is "simply" that.

edit on 4-12-2010 by NIcon because: (no reason given)

reply posted on 4-12-2010 @ 03:06 PM by pteridine

Originally posted by turbofan
reply to post by pteridine

Is this your complete submission?

I notice you didn't show your work for specific energy release of the elements found which is what your entire
argument is based upon.

IE: You must show that combustion of certain elements created a significant amount of heat above and
beyond such mixtures as basic conventional thermite, etc.

Do you plan to include any sort of support, links, science for your claims, or shall we work with your initial
post?

Let me know and I'll begin the reply.
edit on 4-12-2010 by turbofan because: (no reason given)

As I said, I don't have a lot of time right now. The above is 20 minutes worth of review; see what you can do with it. Jones measured the energy releases. He measured more than is possible in any combination of thermite and high explosive without combustion in air occurring. This is based on Jones' data as presented in his paper, so that can be your reference. What else do you need a reference for?

edit on 12/4/2010 by pteridine because: (no reason given)

reply posted on 4-12-2010 @ 03:26 PM by pteridine

Originally posted by NIcon
The first thing I noticed was a not careful reading of the paper:

"Proceeding from the smallest to largest peaks, the yields are estimated to be approximately 1.5, 3, 6 and 7.5 kJ/g respectively. Variations in peak height as well as yield estimates are not surprising, since the mass used to determine the scale of the signal,shown in the DSC traces, included the mass of the gray layer. The gray layer was found to consist mostly of iron oxide so that it probably does not contribute to the exotherm,and yet this layer varies greatly in mass from chip to chip."

I'm happy that you pointed this out. What this means is that the more gray layer there is, the lower the heating values will be. If any gray layer is present, the values will be low. You must conclude that all the energy values are then low, since all contain some gray layer. This makes the disparities even larger and indicates that there must be energy due to combustion. Further, as materials recovered from the DSC were incompletely reacted due to self-extinguishing nanothermite, the values are lower still. Given this, significant combustion must have occured to provide the energy.
Thermite will react in the absence of air but the matrix will not burn without air. What key experiment should be done to show the possible presence of thermite?

reply posted on 4-12-2010 @ 04:07 PM by NIcon

reply to post by pteridine

Yes, the numbers would be higher if we were to remove the gray layers and they completely combusted. However, we know all ready they put more than the elements of thermite into the DSC, and we know that some of it combusted when they say "In the post-DSC residue, charred-porous material and numerous microspheres and spheroids were observed." I take charring as equal to combustion.

Also as I pointed out to you before, that guy from France said his whole sample combusted but still did not create elemental iron. I would think that if the reduce iron was formed from simple combustion it would have occurred with him too, especially since all of his sample combusted.

There must be an explanation of how the iron oxide got reduced.

So, what I'm missing in all of this is a simple combustion formula that would explain how the iron got reduced. Can you help me with that? Do you have any explanation for it?

Edited to add: Please don't reply as from now on I'll stand back and just watch the debate between you and Turbo.

edit on 4-12-2010 by NIcon because: (no reason given)

reply posted on 4-12-2010 @ 04:11 PM by turbofan

This is somewhat misleading. As I will explain below, the amount of heat transferred back into the DSC machine
can be determined using the exotherm trace.

Jones does not state if he used pans with lids or open pans [a peer review would have noted this and had him be specific].

I will explain how the use of lids is irrelevant to the experiment and the conclusions drawn.
The diagrams used in this thread are drawn by me and may be used as a reference when quoting my text within this summary.

The image below is a basic block diagram of what you might see in the typical DSC machine:
- A platen
- Some sort of heating element
- Sensitive temperature monitor

As you will see, there are two plates; one is empty and one holds the object to be tested. The empty chamber on the top left is used as the control plate. You can monitor the amount of heat sourced to the plate; the amount of heat stored in the plate; the amount of heat leaving the plate.

This is possible because you have a known temperature for the heating source as well as the ambient temperatures. Since heat cannot be created out of thin air, we can conclude that any heat leaving the control platen is released into the atmosphere.

In essence, you can subtract the platen temperature from the sourced heat and determine the rate at which the ambient air is cooling the platen, and also the degree of change (delta) between the two.
This is a typical function of Thermal Vacuum Chambers (TVAC) and Hotplates which I use daily in my lab at work. I’ll be happy to show pictures for those that would like to see one in action.

On the top right you see the exact same configuration, but this is where you place your sample to be tested. Normally, you start testing with a sample that is at room temperature along with the platen. Therefore there is very little heat transfer occurring at the beginning of the test.

As you heat up the platen, some heat will escape into the atmosphere, or inside of the chamber in the case with the DSC. If the lid is missing, or installed it wont matter because both sides will lose the same amount of heat at equal rates. This is why we don’t concern ourselves with this minor attribute. If it becomes a concern, I can e-mail Dr. Jones and ask whether he used the lids, or not. My estimate is that he setup the machine exactly as LLNL to produce the most accurate results.

Moving forward, I will now explain how the exotherm trace is produced and how we can interpret the basic dips and peaks.

On the bottom right, we have a platen which is heating up along with the device under test (D.U.T.). Just as with the control side, heat is leaving the plate into the atmosphere but it is also transferring into the D.U.T. Since the control side does not have a mass sitting on top, there will be no heat lost to a mass. This is where the “Differential” comes into play. The trace is drawn based on the differences between the control platen and the test platen.

If we were to pick up the DUT from the test side of the platen, it would feel warm (or hot) because the heat from the plate has transferred to the DUT. Since we know the rate of heating, and the amount of heat lost to the ambient environment, we can conclude that any dip in the trace is heat stored in the DUT , or additional heat radiated by surface area.

The TVAC and plates that I use at work can sense temperature stability and delta down to 0.00001 of a degree Celsius. This is extremely precise; about the resolution to measure the change in temperature of a pool if you were to spit in it. The DSC machines are probably more accurate, I would have to look up the specifications to know for sure.

Now we know how a dip in the trace is produced. So how about the peaks? Since heat cannot be created out of thin air, the peak shown in Jones’ graph must have been additional heat from the chip which began ignition around the 420’C point on the x-axis.

Pteridine contradicts himself when he says you can calculate the amount of energy per unit mass, but there is no way to tell how much temperature is created from the reaction. Really?
So if we know the rate of heating (10’C), and we know the specifications of the platen, and we know the control temperatures, can we not deduce the amount of heat put back into the plate by the energy release by the reaction of the chip?

Pteridine, are you stating for the record that the height of the peak, and the width of peak cannot display the amount of energy used to raise the temperature of the platen?

The temperature shown on the x-axis is the furnace temperature, not the sample temperature, so there is no way of directly measuring flame temperature.

So, “Pteridine” if the x-axis is just the furnace temperature and not the sample temperature where did all of that extra heat come from in the exotherm trace? Watts/gram remains close to zero until 420'C; can you not convert
Watts/gram into heat?

We know the rate of heating was 10’C per minute. Please clarify this point so we can move forward, or concede that the reaction temperature indeed does show up in the trace.

edit on 4-12-2010 by turbofan because: Clarify exotherm question

reply posted on 4-12-2010 @ 06:11 PM by bsbray11

I didn't even have to open this thread to find an error. Niels Harrit's name is misspelled in the thread title, despite it being bantered about this forum for well over a year. Maybe that sounds trivial but it is an honest indication of the amount of attention being paid to detail. It just makes me ask myself, what other inaccuracies is this person perpetuating after so many months of already arguing about it? Spelling is nothing compared to chemistry or the mechanics of military-grade energetic materials.

Originally posted by turbofan
Is this your complete submission?

I notice you didn't show your work for specific energy release of the elements found which is what your entire
argument is based upon.

The "20 minutes worth of review" is not even worth reading, and wasting other peoples' time, since it's nothing but one person's unverified opinion of a technical issue. What is the point in social commentary on technical issues, when you could just do the technical work and make your commentary something that can be verified? Then you don't even need to state your opinion.

edit on 4-12-2010 by bsbray11 because: (no reason given)

reply posted on 4-12-2010 @ 06:16 PM by turbofan

ha, yes...I'm not sure how he's going to prove his point without showing his work.

This shuold be a quick debate, and I'm looking forward to discussing heat and reaction temps. once
Pteridine clarifies my question about the trace.

P.S. I made an oversight in my reply. The rate of heating is 10'C/minute, not 10'C. My editing period has
expired unfortunately!

reply posted on 4-12-2010 @ 08:23 PM by pteridine

Your configuration is over simplified. For details, check the link I provided to the instrument maker. Both platens have sample boats. One has the sample and one doesn't. They are in an insulated chamber. Sometimes, granular alumina diluent is used in both boats; sample is in only one boat. This provides some thermal inertia which is useful in some analyses. Use of a lid does make a difference. The lid prevents energetic sample from leaving the sample boat, which will cause a sharp baseline shift or other electronic noise and ruin the experiment. When running in air, the presence or absence of a lid changes the rate of combustion. Heat flow is what is measured. The x-axis is the temperature of the platen/furnace that is being ramped up at 10C/minute while the y axis shows the heat flow in or out of the sample. The instrument can display the heat flow as watts. If the weight of the sample is known, it can be displayed as watts per unit mass. When calibrated, integration under a peak will provide total energy flux for that event. This is what Harrit did. I have no argument that the instrument measured the integrated energy flux for the fraction that actually reacted.

The exotherm came from chemical reaction, some or all of which was combustion, given the energetics. Because the experiment was run in air, we cannot discriminate between combustion and other reactions.

There is no direct measure of the sample temperature during, for example, a chemical reaction. If there was, Jones could say that the reaction reached "x" degrees. All he can do is say that the reaction started at a certain temperature and was complete at another temperature but not how hot the reaction was.

All Jones need do is to repeat the experiment under argon. Thermite will react and binder will not combust. Until he does, he cannot legitimately claim the possibility of thermite.

reply posted on 4-12-2010 @ 08:58 PM by turbofan

Originally posted by pteridine Heat flow is what is measured. The x-axis is the temperature of the platen/furnace that is being ramped up at 10C/minute while the y axis shows the heat flow in or out of the sample. The instrument can display the heat flow as watts. If the weight of the sample is known, it can be displayed as watts per unit mass. When calibrated, integration under a peak will provide total energy flux for that event. This is what Harrit did. I have no argument that the instrument measured the integrated energy flux for the fraction that actually reacted.

So you agree that the trace can exhibit the amount of heat transferred back into the platen based on your
reply?

IE: The height of the peak; the slew of the trace; the duration between Temp 2 -Temp 1 indicate the amount
of energy released.

Afterall, the trace is based on the difference in temperature between the control platen and test platen.

The exotherm came from chemical reaction, some or all of which was combustion, given the energetics. Because the experiment was run in air, we cannot discriminate between combustion and other reactions.

You do realize that the LLNL experiment was performed in air, correct? You do know that Tillotson claimed
an energetic reaction even though he ran the experiment in air, correct?

I will link and source the LLNL data once you answer the above question regarding heat transfer back into the
test platen. At that point we can discuss your other claims.

edit on 4-12-2010 by turbofan because: (no reason given)

reply posted on 5-12-2010 @ 07:28 AM by -PLB-

Seems to me the issue put forward by pteridine is pretty straight forward and shows that the DSC experiment is inconclusive. Simply put, the measured kJ/g is greater than a thermite or explosive reaction could possibly produce, so there has to be another reaction that produces at least the additional heat energy. In order to rule out combustion, the experiment has to be repeated in an argon atmosphere.

Basically all the experiment tells us that an exothermic reaction has happened, of which at least part is not a thermite reaction. Whether any thermite reaction has happened at all is in no way established.

reply posted on 5-12-2010 @ 08:02 AM by turbofan

reply to post by -PLB-

And when you and Pteridine learn the temperatures required to produce spheres which contain elemental
Iron from Iron Oxide you will understand that combustion is just a small portion of the total heat.

This will be covered as soon as we get a clarification on whether Pteridine believes heat can be transferred
back into the DSC platen during a reaction. Hopefully both of you know the difference between temperature
and heat?

Do yourself a favour and study the Tillotson LLNL data before making such ignorant claims. Tillotson used
the presence of oxygen in his experiment, and Jones did the same do duplicate the environment.

That is how science works. You don't alter a known procedure and expect to compare similar data.

edit on 5-12-2010 by turbofan because: (no reason given)

reply posted on 5-12-2010 @ 08:56 AM by -PLB-

Originally posted by turbofan
reply to post by -PLB-

And when you and Pteridine learn the temperatures required to produce spheres which contain elemental
Iron from Iron Oxide you will understand that combustion is just a small portion of the total heat.

So where does the rest of the heat come from? We can tell for certain that in one experiment about half did not come from a thermite or explosive reaction. So the other half came from other reactions. If just a small fraction was combustion, what reaction exactly produced the heat of that other half.

Do yourself a favour and study the Tillotson LLNL data before making such ignorant claims. Tillotson used
the presence of oxygen in his experiment, and Jones did the same do duplicate the environment.

That is how science works. You don't alter a known procedure and expect to compare similar data.
edit on 5-12-2010 by turbofan because: (no reason given)

It seems to me the significant difference between those experiments is that in the one by Tillotson the exact composition of the materials was known. So it was known no combustion could take place, and an inert environment would not make a difference. In case of the experiment by Harrit, the substance was unknown, so no prediction about what reaction would take place could be made.

reply posted on 5-12-2010 @ 09:30 AM by turbofan

Originally posted by -PLB-So where does the rest of the heat come from? We can tell for certain that in one experiment about half did not come from a thermite or explosive reaction.

Show your source and quote the data please.

It seems to me the significant difference between those experiments is that in the one by Tillotson the exact composition of the materials was known. So it was known no combustion could take place, and an inert environment would not make a difference. In case of the experiment by Harrit, the substance was unknown, so no prediction about what reaction would take place could be made.

THis makes absolutely no scientific sense at all. Are you stating that a DSC machine cannot distinguish
between combustion and a rapid aluminothermic reaction?!

Please link the Tillotson document you are referring to. Note the composition of the material you are describing and then try to apply your theory about combustion.

edit on 5-12-2010 by turbofan because: clarify question

reply posted on 5-12-2010 @ 09:36 AM by pteridine

reply to post by turbofan

As has been correctly stated, Tillotson, et al., knew what they had made. There was no mystery as to the composition and they weren't concerned about combustion. The Jones team had a lapse of judgement and erroneously ran a DSC in air of a material that contained carbon. That they did so shows either lack of analytical chemistry skills or a predetermined conclusion that they had thermite. In either case, their conclusions are invalid. What they should have done was to rerun it under Argon as soon as the data showed significant amounts of combustion were occurring. They didn't and now cannot make claims that a thermite reaction had occurred.
The steps that they should now take are:
1. Run the DSC under Argon or nitrogen. No reaction means "paint."
2. If there is a reaction, then they must determine what the reaction is.
3. Once they have done this, they must then show that the purpose of the material was for demolition. As we have seen in many threads, paint-on thermite is more of a beam warmer than a demolition material. Remember that Jones estimated that 10 tons of this material was in the dust.

As I have stated previously, this crew began their experiments with their conclusion in mind.

reply posted on 5-12-2010 @ 09:37 AM by -PLB-

Originally posted by turbofan
Show your source and quote the data please.

Its in the Harrit paper. Energy denisty of 7.5 kJ/g was reported, as stated by pteridine in the OP.

THis makes absolutely no scientific sense at all. Please link the Tillotson document you are referring to.
Note the composition of the material you are describing and then try to apply your theory about combustion.

Why doesn't it make any sense? I read just a summary of the study by Tillotson in FY1999 (linked by you somewhere), and it says:

We synthesized a prototype nanocomposite by crystallizing ammonium perchlorate (AP) within the pores of an organic gel in FY1998. In this composite, the AP acts as an oxidizer with the hydrocarbon gel skeleton serving as the fuel.

So they knew the composition of the material, unlike Harrit with his experiment.

edit on 5-12-2010 by -PLB- because: (no reason given)

reply posted on 5-12-2010 @ 09:43 AM by turbofan

reply to post by pteridine

Pteridine, please stay focussed. You have failed to answer the question twice. Here it is again:

Do you agree that heat can be transferred back into the test platen during a reaction of the material.

Yes, or no?

reply posted on 5-12-2010 @ 09:55 AM by pteridine

Originally posted by turbofan
reply to post by pteridine

Pteridine, please stay focussed. You have failed to answer the question twice. Here it is again:

Do you agree that heat can be transferred back into the test platen during a reaction of the material.

Yes, or no?

Turbofan, please stay focussed. We are discussing Jones' data, not the operation of the DSC. Heat flux is determined by relative temperatures. What is the point of your question?

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