Observed Temperatures around 1000°C and Sulfidation in WTC 7 Steel
One of the relatively few previous peer-reviewed papers relating to the WTC collapses provides "An Initial Microstructural Analysis of A36 Steel from WTC Building 7." This brief but important letter states:
While the exact location of this beam could not be determined, the unexpected erosion of the steel found in this beam warranted a study of microstructural changes that occurred in this steel. Examination of other sections in this beam is underway.
ANALYSIS 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 by a process similar to making a “blacksmith’s weld” in a hand forge. (Barnett, 2001)
How were these ~1000°C temperatures in the steel beam achieved? As noted above in the quotation from Eagar, it is difficult to reach temperatures above 650°C in the type of diffuse fires evident in the WTC buildings, let alone in the steel columns where heat is transported away by the enormous heat sink of the steel structure. So the high temperatures deduced by Barnett, Biederman and Sisson are indeed remarkable.
Then there is the rather mysterious sulfidation of the steel reported in this paper -- What is the origin of this sulfur? No solid answer is given in any of the official reports.
Of course, there is a straightforward way to achieve 1000°C temperatures (and well above) in the presence of sulfur, and that is to use thermate (or a similar variation of thermite). Thermate is a high-level thermite analog containing sulfur developed by the military (see
dodtechmatch.com. Thermate combines aluminum/iron oxide (thermite) with barium nitrate (29%) and sulfur (typically 2% although more sulfur could be added). The thermate reaction proceeds rapidly and is much faster than thermite in degrading steel leading to structural failure. Thus, both the unusually high temperatures and the extraordinary observation of steel-sulfidation (Barnett, 2001) can be accounted for -- if the use of thermate is allowed in the discussion. Note that other oxidizers (like KMnO4) and metals (like titanium and silicon) are commonly used in thermite analogs.
Finally, sulfidation was observed in structural steel samples found from both WTC7 and one of the WTC Towers, as reported in Appendix C in the FEMA report. It is quite possible that more than one type of cutter-charge was involved on 9/11, e.g., HMX, RDX and thermate in some combination. While gypsum in the buildings is a source of sulfur, it is highly unlikely that this sulfur could find its way into the structural steel in such a way as to form a eutectic. The evidence for the use of some variant of thermite such as sulfur-containing thermate in the destruction of the WTC Towers and building 7 is sufficiently compelling to warrant serious investigation. |
