Merged "Iron-rich spheres" - scienctific explanation?

After some googling, I found a paper showing that iron-rich microspheres can be formed (basically from the rust) even at room temperature, here after the immersion of samples in a sea water.

First, the steel was painted with the stuff called Dacromet, containing fine zinc and aluminium powders, and then immersed in sea water for 50 days. Here are micrographs of some area.

Authors' comment to Fig. 3a: "As can be seen from Fig. 3a, some loose spherical rust particles form around the cracks". XEDS spectrum in Fig. 3b basically corresponds to iron oxide.

I'm not saying that this is an explanation of iron-richer round objects in Bentham red-gray chips heated in DSC, but it is again a clue that such iron oxide spheres can be formed in various not really expected ways:cool:
 
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Ivan Kminek said:
After some googling, I found a paper showing that iron-rich microspheres can be formed (basically from the rust) even at room temperature, here after the immersion of samples in a sea water.

First, the steel was painted with the stuff called Dacromet, containing fine zinc and aluminium powders, and then immersed in sea water for 50 days. Here are micrographs of some area.

Authors' comment to Fig. 3a: "As can be seen from Fig. 3a, some loose spherical rust particles form around the cracks". XEDS spectrum in Fig. 3b basically corresponds to iron oxide.

I'm not saying that this is an explanation of iron-richer round objects in Bentham red-gray chips heated in DSC, but it is again a clue that such iron oxide spheres can be formed in various not really expected ways:cool:
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Good find, mate!
 
Btw, as I have discussed in the thread WTC Dust Study Feb 29, 2012 by Dr. James Millette (posts 889 - 893), even the highly crosslinked polymer binder in the anticorrosive primers must allow some diffusion of air and water into/through the paint layer; otherwise, the sparingly soluble anticorrosive chromates pigments which are present can't dissolve and can't form a very thin passivation layer on the steel.

Therefore, perhaps such long-time corrosion with water vapors can lead to the slow formation of iron oxide "spheres" on WTC primered steel, which could explain "round shiny objects" found in some red-gray chips without any heating (which are regarded as "partially reacted nanothermite" by truthers). (Just a guess, nothing more:cool:)
 
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alienentity said:
Has it been documented?

btw you guys are total geeks. I mean that in a nice way ;)
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Thanks:cool: You mean these „partially reacted nanothermite chips“? I have seen them, but I just don’t remember where. They are not so important, since they could be anyway paint chips accidentally exposed to high temperatures during the disaster.

Considering Sunstealer’s idea that „microspheres“ seen in the Bentham chips after heating in DSC device up to 700 degrees C were formed basically from gray layers (highly probable), it is good to do some further literature search using phrases like “steel high temperature corrosion”.

E.g., I have found this fine paper dealing with the formation of oxides on stainless steel at 750-800 degrees C.

Some round iron oxide-based objects are clearly formed (they are called “nodules” here) at 800 degrees C, see this picture:

Interestingly, very fine oxide fibers called whiskers are growing on the surfaces of these nodules, see this picture.

Well, this paper is not really relevant as for the behavior of carbon steels used for WTC floor trusses, perimeter panels etc, but it again shows how immensely naïve are truthers “hypotheses” that no iron-rich spheres can be formed well-below the tabulated melting points of iron or iron oxides:cool:
 
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Ivan Kminek said:
Btw, as I have discussed in the thread WTC Dust Study Feb 29, 2012 by Dr. James Millette (posts 889 - 893), even the highly crosslinked polymer binder in the anticorrosive primers must allow some diffusion of air and water into/through the paint layer; otherwise, the sparingly soluble anticorrosive chromates pigments which are present can't dissolve and can't form a very thin passivation layer on the steel.
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Not quite - I think you have it backwards. My understanding is thus:

When structural steel stays dry, its surface oxidizes, but doesn't rust - the structural difference being that rust comes with a serious change in volume, and flakes off. This increases the surface, and decreases material thickness, and in the long run, after so and so many circles of rinse and repeat, your steel wears thin. It is incorporation of H2O into the oxide layer that makes steel rust (and also greatly increases the rate at which the surface wears.)

"Dry" oxidation mainly leads to protective, smooth oxide layers, in contrast to hydroxide phases.

The main aim of a protecting coat is thus to keep away water - it HAS to be water proof. It is no problem if it is also airtight, because the steel surface is already oxidized (but rust-free) before painting. Howeber, oxigene does slowly diffuse through the coating and over a long time, the oxide layer forms more fully.

Protective pigments like chromates probably come into play where the coating is not water-proof - due to imperfect application or mechanical stress perhaps: IF water can seep through to the steel surface, it ALSO gets to the chromate which can then and thus do its "healing" work.

Ivan Kminek said:
Therefore, perhaps such long-time corrosion with water vapors can lead to the slow formation of iron oxide "spheres" on WTC primered steel, which could explain "round shiny objects" found in some red-gray chips without any heating (which are regarded as "partially reacted nanothermite" by truthers). (Just a guess, nothing more:cool:)
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Perhaps, but not typical, and anyway the SEM-images of the gray layers (pre-heating *)) do not reveal in any way the presence of spheres or anything coming close. Also, Harrit e.al. swear that no such spheres were found in any chips before heating, but were plentiful after heating. In the absence of good evidence to the contrary, I'd prefer to take their word on this.



*) Note my deliberate choice of the word "heating", as opposed to "burning" or "reaction" - I am beginning to lean toward the conclusion that no significant amount of iron compound reacted chemically in any way when they formed spheroid and other roundish particles. In Mark Basile's experiment, for example, I suspect that the stainless steel strip that he placed his probes on may have reached a very high temperature and have affected the morphology of the gray layer significantly.
 
Ivan Kminek said:
...it again shows how immensely naïve are truthers “hypotheses” that no iron-rich spheres can be formed well-below the tabulated melting points of iron or iron oxides:cool:
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This point can't be stressed enough. Dave Thomas makes it by burning steel wool - a process easily reproducible in one's own home, that requires no greater source of energy than a cigarette lighter. Truthers pf course fail to get the relevance: That this is only an example for how iron microspheres can form at usual fire temperatures and outside the heat conditions of a furnace.


It is application of simple logic: A claim of the form
All X have property Y​
can be proven FALSE by presenting one X that does not have property Y.

Examples:
All Germans are Nazis​
can be disproven by presenting me - I am German, but I am not a Nazi.

All days in London are foggy​
can be disproven by showing, from the meteorological record, that there was no fog in London yesterday

All self-identifying 9/11 truthers dismiss all evidence and facts that don't support inside-jobby-job​
can be disproven by pointing out that BCR self-identifies as a 9/11 truther and has presented lots of evidence and fatcs not in line with inside-jobby-job

All iron microspheres form at ambient temperatures above the melting points of iron and iron oxide​
can be disproven by showing that some such sphere form at lower temperatures when steel wool is burned, iron oxide is submerged in salt water in the presence of aluminium and zinc, etc.


All these refutations, showing that the general claim is false by presenting one contrary example, open up the possibility that some, many, most, even all other X's likewise do not have property Y.


However, this doesn't mean that truthers have to fully retract the claim. One possible option is to refine the claim: Either by defining X and Y more specifically (all X, that are also V and W, are Y), or (and this is where they ought to go if they are smart, because, again, the more specific but still absolute claim runs the risk of being disproven by one single example to the contrary) by replacing the absolute claim "all ... are" with something that includes probabilities ("more than z% of all X are Y"). Or actually a combination of both (under conditions W and V, more than z% of all X are Y). The problem is of course to justify such a claim, especially the estimation of the probability. That problem is however theirs - we don't have to refute a claim that they haven't even made and justified yet.
 
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Oystein: during this morning, I have attempted to be more "amateur metallurgist" than polymer chemist (which I actually am:o), but OK, let me again consider crosslinked polymers, namely epoxy resins, for the moment.

Epoxy resins are cross-linked polymers with moderate polarity (they contain a lot of organic polar groups like e.g. hydroxyls) and we can expect that they absorb some water.

A quote from this paper:, titled Water Sorption and Diffusion Studies in an Epoxy Resin System:

"Epoxy resins are widely used... However, it is well known that these properties are strongly affected by moisture absorption, which causes plasticization... etc. So the transport of moisture in epoxy resin systems is of great importance, and the kinetics of absorption and distribution of water in the polymeric matrix is still under investigation."

After the quick look into the paper, it seems that just these epoxy resins (classical DGEBA-based, cured with TETA) can absorb ca 2 % of water, which can diffuse through the matrix.

You are probably right that the anticorrosive action of chromates is more important for the imperfect/damaged epoxy films, but even for perfect films, some water can be present in them (namely at high humidity) and can dissolve some chromates (although very, very slowly).

Simply: no usual crosslinked polymer binders (epoxies, polyurethanes, polyesters, alkyds, melamine resins) are perfectly "water proof", since all of them have moderate polarity and absorb some water. Molecules of water are anyway small and can "fit" to the voids/"free volume" of the crosslinked resin. Only in films of non-polar polymers like polyolefines, teflon or e.g. polystyrene, the absorption/diffusion of water is negligible.
 
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Ivan,

I don't doubt that is correct. My further understanding is that one main reason to put iron oxide pigments in the epoxy, rather than just coat them with pure epoxy (or epoxy with some chromate), is because it helps to stop or slow water diffusion through the paint. I read things to that effect in a couple of papers, but am too lazy now to search for them. Iron oxide pigments have no chemical properties that would make it protective; it's this physical property of stopping water that makes it useful.
 
Oystein: Hehe, I'm not saying that I understand the anticorrosive primers, I've only pointed out that pure epoxy resin (and similar binders) absorbs water, which can diffuse in it.
Here is some table with water absorption data for various polymers, just epoxy is missing.

What is the actual purpose/action of iron oxide in such primers is indeed interesting question...

Anyway, we are completely off-topic now, in the microsphere thread.
 
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Oystein: last remarks as for iron oxides, since it is on topic here.
As you said, iron oxide pigments seem to be basically "inert" in anticorrosion primers, and they are used owing to some good properties like low price, good absorption of light, compatibility with paint binders, proper sorption of water etc. As any other primer pigment, iron oxide slows down the diffusion of water through the paint polymer matrix (among others), simply because its particles act as obstacles for water.

In any case, the microspheres with a metallic luster in Fig. 20 (Bentham paper) seem to be formed not from the iron oxides in red paint layers, but from gray rust layers instead (as Sunstealer suggested):cool:
 
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Which begs the question: why did the gray layers sometimes turn roundish at their edges?
 
Oystein: Yesterday, I have found some papers which show that during "hot corrosion" of steel, "nodular" kind of rust (round particles of iron oxides) can be formed from the steel, probably even below 700 degrees C.

But in heated Bentham chips, microspheres are very probably formed not directly from the unoxidized steel (if any present in the spalled gray layers), but mostly from the already formed iron oxide layers (mostly wustite and magnetite at temperatures higher than ca 600 degrees C).
Iron oxide phases are/can be separated in such a rust before (and during) heating, like I see e.g. here, and can form domains of rounded shapes. Therefore, some round edges of gray layers may be formed by the separation of these phases during cracking of the paint layer. (Just an amateur guess, nothing more:cool:). And, perhaps such phase separation may somehow contribute to the formation of microspheres at high temperatures.

Btw, there is an interesting "animation" in the link above, which shows how iron oxide nodule ("half-microsphere") looks in detail/crossections (in the stainless steel).
 
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Ivan, these "nodules" you link to grow out of stainless steel, and the author suggests that they "form at protective chromium oxide break-down sites at phase/grain boundaries in the substrate". Stainless steel is rich in chromium (>10%), so this is probably not the kind of process we are looking for.

I find the images of the different phases in oxide scale more interesting. I speculate that some change of particle shape may be due to changes in the microstructure, when partially oxidized iron (magnetite, wüstite) oxidizes even further, or perhaps gets partially reduced in the presence of CO from charring epoxy, or perhaps water is released, or FeO and Fe3O4 split to Fe and Fe2O3, etc.
I probably make the metallurgists around here cringe :D



A couple of cautionary reminders:
  1. There is no need to accept the truther premise that microspheres of any kind mean something sinister, or that they mean something sinister by default if we can't show they are normal. Burden of proof rests with them: They have to exclude the possibility that non-sinistet processes are available, OR show that their proposed process (e.g. thermite) was available (i.e. in fact present; I believe this is why Jones coerced some colleagues into writing this crappy Bentham paper: He realized that his thermite theory wouldn't fly if he didn't have any actual thermite to show; just as he previously invented the thermite theory to start with because he realized that conventional explosive demolition won't convince any sane person in the absence of evidence for actual explosions and explosives).
  2. Iron spheres don't have to come from iron/steel. As Myriad already explained in post #28 of this thread, you can find "shiny ferromagnetic spherical particles by dragging a cleaned magnet through wood ash". We know for a fact that wood burned at the WTC, so there is one source for such spheres that truthers won't be able to exclude, unless they study spheres from wood ash and show them to be significantly different from WTC spheres
  3. For "us", this debate of microspheres is mostly "interesting", because we are geeks, and not because we have an interest in proving anything. For "them", it's really all they have, because all the other supposed "evidence" for CD is not in fact evidence
  4. Even if the debate ends with a conclusion that thermite is the best explanation for such spheres, the buildings are still not proven to have been demolished. There is no evidence for that. If the remains of 100 midgets with 100 metal saws had been found in the WTC rubble, that wouldn't prove that these midgets destroyed the towers. Pointing out that midgets surely COULD probably saw through structural steel somehow doesn't suffice to make that case. It would merely be a strange quirk. You'd also have to show that it was in fact sawing that caused the steel to fail, and you'd have to propose a method by which the midgets could have done it that is consistent with observation (and that addresses the logistical problems of "how long does it take" and "how do you avoid detection" etc.)
 
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Oystein: I don’t cary very much about microspheres in WTC dust, at least now. I’m interested mostly in these rather strange iron oxide-based microspheres with metallic luster formed in the red-gray chips during heating to 700 degrees C in the DSC device.

Looking e.g. to the fluffy appearance of the microsphere depicted in Fig. 21, these objects are not necessarily compact, as they look in Fig. 20 at low magnification, and can be basically formed by the sintering. This term was mentioned several times here in JREF, for now I will add some details and also some tentative explanation as for microspheres in Bentham paper.

Sintering is the process during which particles of something aggregate/agglomerate at temperatures well-below the melting point of this stuff, forming larger particles. Wiki explains: “The atoms (or molecules, I.K.) in the powder particles diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece.” Suitable sintering temperatures seem to be usually about 30 % lower than melting temperatures.

I will consider that red-gray chips in Fig. 20 are mostly Laclede primer chips (or chips of some similar primer). Gray layers should be basically “mill scale” composed of mostly black iron oxides. Notably, such a mill scale is an important by-product of steel manufacture in rolling mills and it is massively recycled in the large facilities called sinter plants (see Wiki). Here, temperatures for sintering are usually between 900 and 1250 degrees C. OK, well-below the melting points of iron oxides or iron, but still higher than 700 degrees achieved in DSC machine. Sinter plants use air as a gas, but powdered coke acts as reducing agent, leading to partial reduction of iron oxides.

Of course, WTC red-gray chips are not pure mill scale. As for red paint layers, we can reasonably expect that epoxy paint binder (or similar binder) is first degraded in air, leading to the formation of some dark polymer char at ca 450-500 degrees C. Such charred, imperfectly burned WTC paint chip was shown by Mark Basile in his presentation, at the time 43:04 here. At even higher temperatures, char is further oxidized/burned under air, but before the burning is complete, it can perhaps act as a reducing agent for iron oxides (as we have discussed many times). Anyway, above ca 650 degrees C, red layers should contain basically only kaolinite and hematite particles (therefore they are no more dark, but again red, see Fig. 20).

And back to the gray-layers of mill scale. If they were basically compact/continuous before heating (which we do not know), the formation of separated microspheres by sintering can be probably explained only if there are some processes which disintegrates mill scale during heating to some smaller pieces. I think that such processes are possible: e.g., (as Oystein noted), iron oxides are further oxidized/transformed with the increase/change of volume, phases of various iron oxides can be separated, etc, simply gray layer can be somehow “ destroyed”. Such disintegration can be be "pushed" by the significant changes in attached red layers.
Still, it is fully possible (and perhaps more probable) that microspheres were created from the separated pieces of gray layers which were originally present in the unheated chips.

At sufficiently high temperature, such pieces of mill scales can start to sinter. E.g. here is the reference that magnetite can be sintered already at ca 500 degrees C (unfortunately, the whole text is not available for me). Kaolinite (and nanosized iron oxide) in the red layer can probably “co-sinter” during such process, which can explain the presence of Si and Al peaks in the XEDS spectrum of one microsphere (Fig. 25).

I am not saying that the word “sintering” explains everything (and I admit that I haven’t written anything basically new, probably Sunstealer had explained the things better in the prehistory of this long debate). Namely, it is not really easy to explain solely by sintering why all remnants of gray layers are purely spherical after heating. Here, some other processes can be also responsible, which I do not know.

Anyway, sintering of mill scales/gray layers at comparatively low temperatures is possible and has been routinely used in the steel industry for decades – which was perhaps my main point here:o)
 
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Ivan,

I have come across mentions of sintering here and there when reading various abstracts dealing with ash formation. McCrone's Particle Atlas Vol. III shows plenty of glassy spheres (silica, silicates) and magnetite spheres, often commenting that these indicate high temperatures and relatively complete combustion, and when sintering is mentiones ("sintered ash"), it is an additional observation. I can't connect any mention of sintered material to any spheres shown in the corresponding images. Hmm...

The Wiki article descibes a mechanism of grain growth during sintering which tends to fill up concave regions (cavities) and make surfaces more smooth:
http://en.wikipedia.org/wiki/Sintering#Grain_growth
I think this would tend to make particles more spherical, but I don't think it would be as efficient as, and wouldn't produce quite the same quality of sphericity, as surface tension on a cooling liquid.
 
Oystein: OK, according to wiki, so-called Ostwaldt ripening (sounds good:cool:) is an important process during sintering of any powder (larger particles "eat" smaller ones and become rounder at temperatures above ca 70 % of melting point of the stuff), but microspheres in Fig. 20 seem to be still "suspiciously" spherical for such low-temperature experiments.

Probably only Ostwaldt ripening in a typical two-phase system we have here (paint/rust bilayer) can explain the formation of distinct microspheres (one phase "does not like" other one, leading to the minimizing/rounding of its surface, etc)... it is perhaps a matter of several weeks of study - and a theme for some PhD thesis, but who would pay for it?

Since (among others) the whole concept of thermitic CD of WTC is a very clear idiocy and no metallic aluminium components of thermite were found by Jim Millette, there is no need to prove that such microspheres can be formed in the WTC primer paints heated to 700 degrees C without thermitic reaction, as you/we have noted maybe fifty times (?). They were simply formed in paint chips attached to oxidized steel (together e.g with some translucent microspheres created probably from silicate or other non-metallic stuffs). Period (so far):o)
 
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