Nanothermite vs. Thermite/Thermate for Cutting Thick Steel

[Cantonear1968]

A question for people more educated than I: does Thermate lower the melting temperature of iron?

The full quote that I am dealing with:

"Sulfur generates a eutectic system when molten thermate interacts with iron or steel lowering the melting point of iron. Wikipedia"

Looking up the wikipedia page on thermate here.... https://en.wikipedia.org/wiki/Thermate ...I do not find that sentence. And I have searched but found nothing to corroborate his statement. My belief is that he is confusing "ignition temperature" with "melting temperature". Or does not understand the difference between "melting temperature" and "intergranular melting".

This is of course in connection with the FEMA Appendix C paper. I'm waiting for clarification from the poster but thought I would post the question here.

 

[deirdre]

I do not find that sentence.

it might be in reference to this?
from "journalof911studies.com"

The observations of Barnett, Biederman, and Sisson (BB&S) (See Footnote 2) describe sulfidation of some structural steel from WTC 7. They say:"Rapid deterioration of the steel was a result of heating with oxidation in combination with intergranular melting due to the presence of sulfur. The formation of the eutectic mixture of iron oxide and iron sulfide lowers the temperature at which liquid can form in this steel. This strongly suggests that the temperatures in this region of the steel beam approached ~1000 C, forming the eutectic liquid by a process similar to making a "blacksmith's weld" in a hand forge."
9 And they conclude:"The severe corrosion and subsequent erosion of Samples 1 and 2 10 are a very unusual event. No clear explanation for the source of the sulfur has been identified. The rate of corrosion is also unknown. It is possible that this is the result of long-term heating in the ground following the collapse of the buildings. It is also possible that the phenomenon started prior to collapse and accelerated the weakening of the steel structure."

this book lists the reference paper as

'An Initial Microstructural Analysis of A36 Steel from WTC Building 7' by ER. Barnet, RR Biederman and RD Sission, jr-which was published in the December 2001 issue of the Journal of the Minerals, Metals and Materials Society

and here is a thread (I haven't read) that seems to be discussing Sisson/sulpher https://www.metabunk.org/sulfur-at-wtc7-how-could-it-come-from-gypsum-as-the-bbc-claimed.t3383/

 

[Cantonear1968]

it might be in reference to this?
from "journalof911studies.com"

The observations of Barnett, Biederman, and Sisson (BB&S) (See Footnote 2) describe sulfidation of some structural steel from WTC 7. They say:"Rapid deterioration of the steel was a result of heating with oxidation in combination with intergranular melting due to the presence of sulfur. The formation of the eutectic mixture of iron oxide and iron sulfide lowers the temperature at which liquid can form in this steel. This strongly suggests that the temperatures in this region of the steel beam approached ~1000 C, forming the eutectic liquid by a process similar to making a "blacksmith's weld" in a hand forge."
9 And they conclude:"The severe corrosion and subsequent erosion of Samples 1 and 2 10 are a very unusual event. No clear explanation for the source of the sulfur has been identified. The rate of corrosion is also unknown. It is possible that this is the result of long-term heating in the ground following the collapse of the buildings. It is also possible that the phenomenon started prior to collapse and accelerated the weakening of the steel structure."

this book lists the reference paper as

'An Initial Microstructural Analysis of A36 Steel from WTC Building 7' by ER. Barnet, RR Biederman and RD Sission, jr-which was published in the December 2001 issue of the Journal of the Minerals, Metals and Materials Society

and here is a thread (I haven't read) that seems to be discussing Sisson/sulpher https://www.metabunk.org/sulfur-at-wtc7-how-could-it-come-from-gypsum-as-the-bbc-claimed.t3383/

Thank you for the response and I'd like to focus on the sentence I bolded. I may be splitting a hair that I don't truly understand, but as I read that it means it achieved a "liquid form" from a corrosive attack instead of heating. Yes, at at or around 1000C. But does that mean the "melting temperature of iron is lowered"?

The poster is attempting to say that introducing sulphur to a thermate reaction means iron will actually "melt" at 1000C or there abouts. I see this as different while acknowledging it may all be above my head.

 

[deirdre]

introducing sulphur to a thermate reaction means iron will actually "melt" at 1000C or there abouts.

you'll have to wait for one of the science guys for your answer. But just keep in mind (as far as your conversation partner) the steel in WTC didn't melt.

 

[Oystein]

Disclosure: I am not very much a "science" guy - no background in metallurgy or anything of that kind. However, I have looked into the issue of the FEMA Appx C "intergranular eutectic melting" stuff enough to give a confident answer:

Generally, mixing a metal with something else (alloying...) lowers the melting point.
Think "melt iron, throw in sulfides or oxides or other metals, stir, let cool to solidify": That new material will have a lower melting point than pure iron.

Nit-pick: Not any mix will have a single, well-defined melting temperature: Most of the time, one component will melt (have its crystal lattice dissolved) before the other(s) do(es), which tends to make the material "plastic", like wax. There are certain percentages of material mixes, called "eutectics" or "eutectic systems", where both/all components of the mix melt at the same temperature.

Anyway, melting-mixing-stirring is only one way of creating an allow. On a microscopic level, when two materials get in contact, they will diffuse into one another and thus mix superficially. The surface then has a lower melting point.

As for the steels analysed in that Appendix C, more specifically sulphur-rich species diffused in between the grains of the steel structure - which isn't smooth, it's granular. The process there was:

1. Sulphur (actually: sulphides, sulphites, sulphates or sulphur oxide) diffuse into the intergranular area while hot,
2. lowers the melting temperature on the grain's surface,
3. surface melts,
4. grain falls off,
5. a fresh bit of surface thus gets exposed to the sulphur-rich gases
6. repeat

This is a relatively SLOW process. Biederman et al were not sure whether it took hours or weeks for those steel specimens to lose half an inch or so of thickness. We are, however, definitely NOT talking about seconds here!


Cut back to thermate: It is actually not clear why adding sulphur improves the welding and cutting properties of thermite. It's most probably got more to do with the chemistry of burning sulphur and not with the forming of eutectics in the intergranular cavities.

 

[Cantonear1968]

Thank you Oystein. As much as I expected, the poster came back and stated he uncritically repeated it from a YouTube video. No corroborating evidence.

I appreciate your response on this.