hey sunstealer.
first you argued that "I would agree that this [eutectic reactions] started prior to collapse and helped weaken the structure by reduction in section thickness of the material involved."
Any reduction in cross-sectional thickness will weaken a structure. Looking at the samples then this degradation doesn't look to have been the cause of any failures. Secondly remember that it's not just sulphidation and liquation occurring here. There's plenty of oxidation. In any case for such sulphidation to occur you need high temperatures and that is going to have a far greater effect on the structures ability to carry loads.
it was your contention that such reactions can easily result from jet fuel.
It can, but any source of sulphur and a high enough temperature will result in sulphidation.
the piece in question however was recovered from WTC 7 which was not hit be a plane ths the jet fuel could have been ruled out.
That would seem rational and I've alluded to that.
next Norseman cites that diesel tanks located in the WTC 7 building as the source of sulfur. now the WTC 7 fires were not feed by the diesel fuel tanks prior to collapse.
OK. But that does not mean to say that other combustible products do not emit sulphur dioxide when burnt.
this means that if the diesel fuel was the source of the sulfur it occured during the debris pile which appears to conflict with your earlier assertion.
That would be so, however, that does not rule out other sources of sulphur prior to or after collapse.
so I take it that you now hold the position that the peice of metal which exhibited eutectic reactions occured during the rubble pile from the diesel fuel as the sulfur source.
I take the position that the eutectic produced is likely to start to have been produced due to the fire in the building. Be aware that the steel material will spall thereby exposing material that has not been exposed. If there is sufficient heat and levels of sulphur in the rubble pile then this will continue. I guess you could say that there is no absolute way of knowing whether the corrosion products we see are a result of one or the other, but experience of steel in similar fire conditions, results in similar levels of corrosion so it's pretty good bet to say that what we see was produced in the fire and not the rubble pile.
other characteristics of the steel piece recovered indicate the presence of high pressures for example the edges were curled up like a paper scroll. Does that not indicate something other that eutectic reactions? or have you seen eutectic reactions with this characteristic before?
Could you be more specific with regard to the term "pressure". From your writing it would seem to mean a mechanical pressure (so I'll take it as that), but be aware that partial pressure and atmospheric pressure can affect diffusion rates. I'm not sure what you are asking. A eutectic does not require a pressure to occur, although of course the eutectic temperature will be determined by pressure and if I recall correctly will be raised as pressure is raised due to Claussius-Claperyron equation. In this case it's simply a solidification of a liquid into a two (or more) phase solid. That's what it means metallurgically, I'm not sure there is another definition.
finally, in your opinion, materials exposed to 350ppm jet fuel with air temperatures of 900c for 20 minutes will result in evaporation of those materials?
Absolutely not. For evaporation to occur you firstly require the steel to be in a liquid state. I've no idea at what temperature steel would evaporate. Some materials sublimate i.e. go from solid to gas on heating, but steel is not one of them. I think you have your terminology wrong. Steel in that environment for that time will certainly show signs of corrosion, i.e. a heavy oxide scale, that scale will be incoherent with the parent material and prone to spalling.
and such a reaction is reproducible?-
The experiment would not be difficult to carry out. You can effectively run the test for as long as you like. Imo 20 minutes exposure is not going to give you much data. I'd be looking to run multiple samples (including a control) for anything between 20 mins and 2 hours for WTC1 and 2, but also days if not months if I were looking to see what a rubble pile would produce and that would also have to be at a number of temperatures and atmospheres which would be quite difficult to do.
