"(1) Due to decreased particle size and therefore increased surface area, there is more aluminum oxide to be 'overcome' during a thermitic reaction than with normal thermite."

Well, I think the main point in terms of a DSC test, where you are concerned about energy density (energy / mass), is that the mass contribution of the Al-Oxide does not contribute, in any way, to the energy released by the thermite reaction. In terms of "overcoming" the energy barrier involved in cracking the Al-Oxide shell, while that is critical (at least, according to melt-dispersion theory) in determining overall reaction rate, I don't think it effects the overall heat energy measured during a DSC, at all.

"(2) Due to decreased particle size, and therefore increased surface area, the reaction will occur faster and more violent. The ignition temperature will be lower"

The r0, r1 values I use imply exactly the same particle width (through the narrowest dimension) as the spherical nanoparticles. It is the other 2 dimensions that get extended, in the planar case. I have argued that the more easily cracked planar morphology of Al-Oxide will lead to a lower ignitioin temperature, but a lower reaction rate. This is the guess of a mildl educated layman, so don't put too much stock in it. But it follows, I believe, straightforwardly from the discussion of the melt-dispersion mechanism (discussed in Andrew Francis' thesis MODELING THE MELT DISPERSION MECHANISM FOR NANOPARTICLE COMBUSTION

"(3) The shape of the aluminum platelets serves to maximize the packing density, therefore allowing more aluminum to be available for reaction"

They absolutely maximize packing density by volume of constituents. Note that I have done my calculations by assuming that the total Al + Al-Ox volume is the same in both planar and spherical case is the same. This is the significant density in terms of a DSC test, because the density of Al and Al-Oxide are roughly equal, so this basically amounts to getting twice as much elemental Al in your powder, for a given weight of that powder.

Density by net volume of your powder, that is not so clear, and probably impossible to calculate, exactly. That is because in a real-life powder, your platelets do not extend infinitely in two dimension, nor do they line up parallel to each other. So, think of a box of 'flat' cheese nips compared to filling that box with smallish peas, where the diameter of the peas is the same as the width of the cheese nips, through their smallest dimension (and assume that your peas and cheese nips are the same densities in their outer shells, and their inner cores.) I assume that there is more 'air' in the box of cheese nips than the smallish peas. I.e., I expect that the pea will fill the boxes volume moreso than the cheese nips. Whether there is enough to outweigth the fact that the volume 'Al interior' of a cheese nip is close to twice as large, proportionately, as the 'Al interior' of a small pea, I'm not sure.

What this means is that the energy density by weight (which is what a DSC measures) of a platelet nanopowder would be more than a spherical nanopowder, but the packing density could be less. Just eyeballing the pictures in the Harrit paper, my guess is that the aluminothermic constituents are not packed particularly closely, so that if you did swap out platelets in favor of spheres, you would lose packing density of Al. If we postulate that the chips really are some sort of aluminothermics nanopowders, for military use, then if we further assume that the material is intended for a limited receptacle (like a bullet nose), then the actual packing density become important. So, it's reasonable to question a military origin of the chips is they are not essentially composites, and don't pack Al as efficiently (by volume) as normal spherical Al nanopowders.

"(4) The density fluctuations Dr. Greening talks about are almost irrelevant because they occur after the ignition temperature and near the end of the exothermic peak"

"Fluctuations" was an unfortunate use of terms,by me. Bascially, the main point that I was getting at was that 1) AFAIK, nobody measure DSC's in terms of weights or densities that pertain after the DSC run begins and 2) the density alteration that Dr. Greening speaks about happens near the ignition temperature, and the exotherm is basically narrow (well, to this layman, it is.) From memory, it only pertains to a fraction of the time that the DSC is run, anyway.

In light of 1) , 2) is probably irrelevant.....

I note that I haven't read Dr. Greening's references, but I hope that if there is any significant correction to be made to my argument from geometry, that he post more details so as to suitably tempt me. Nobody is paying me to spend great gobs of my time on this stuff, it has involved a real sacrifice on my part, so I don't feel guilty about not pursuing every reference, when insufficient motivation is provided.

"In other words, the nano-thermite chips Jones/Harrit et al. found are designed so that they overcome the aluminum oxide 'obstacle' in the best way possible. However, so far this discussion is theoretical, and not confirmed by any published experiments."

Yes, my arguments are theoretical. I am a layman, and so even my "theoretical" arguments should be taken with a grain of salt. However, I like to believe that I wasn't born yesterday, so when somebody makes a statement that strikes me as BS, and I can clearly articulate reasons consistent with the physics and math that I do know as to why they are BS, and all they can do is repeat their debunked 'arguments' and talk down to me - well, let's just say that I'm not impressed.

"Furthermore, I don't understand this repeated reference to an 'inert gas' environment. If Tillotson didn't conduct his experiment this way (he doesn't say so anywhere in his paper), and if the chips are designed to ignite in air, possibly using gas expansion from the igniting carbon molecules inside the chips for some purpose, then why is this 'inert gas' argument still used?"

Here, the debunkers certainly have a point. The burden of proof that the thermitic material is just that is on the Harrit team. Since aluminothermics worthy of the name don't need air to react, then why, indeed, would the Harrit team not have done DSC's in a vacuum? Tillotson's material is clearly not identical to the the Harrit material, so comparisons will be problematic, anyway.

It's possible, I suppose (again, I'm a layman) that the organic binder (which, IIRC, is assumed to be combustible) is actually a key constituent - either as a heat source, or as a source of gas, or both - but that it also designed to be combusted in air, and when you do DSC's in a vacuum, the organic binder hinders the alumino-thermic constituent. In a sense, I'm suggesting that the chips are composites that are too 'fuel-rich' such that their aluminothermic constituents can behave as pure aluminothermic, in a vacuum. This is very speculative on my part - just the sort of question that you would ask an expert.

So, the debunkers have put their finger on a good question, but in their usual, arrogant and dismissive way, allowed their abortive thought process to prevent them from honestly seeking alternatives, and asking the sorts of questions that might help elucidate the matter (either for or against any form of nanothermite, I might add). The simple alternative I suggest - not PURE nanothermite, but a 'fuel rich' composite which cannot produce a DSC consistent with pure nano-thermite, is not the sort of question that they will trouble their minds with. Why should they, since they have convinced themselves that the Harrit chips are paint, even if they still haven't produced any burnable chips that yield microspheres in a DSC?

"So far, Mackey's assertions seem to be not only incorrect, but in the broader picture they are also completely irrelevant."

You have to be a little careful, here. Mackey has asserted some valid facts and observations. It's the conclusions that he draws from his observations and, in particular, the framing he is giving them that give him away not as a dispassionate scientist who has a genuine interest in figuring out what the Harrit chips are, but rather an extremely biassed individual who is unwilling to part even with patently bad arguments. That is not the same as saying that everything he says is wrong. Also, we still don't know whether or not some of the debunker arguments are irrelevant, or not.

"Who freaking cares if the energy yield of explosive A is less then incendiary B? The military investigates A because it thinks it's the future of high explosives and/or igniters. A shouldn't be in the WTC dust in the first place should it?"

Beats me. I'm not committed to any view. It strikes me as completely possible that the materical is "thermitic", but not by design, only incidentally. Couldn't the chips be fragments of some electronic material? A coating, say?

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