Heating of red/gray chips of four red paints from the yard of our chemical institute
Hi, all
As for me, I have had basically two remaining questions, regarding “mysterious” WTC red/gray chips investigated by Harrit et al and Millette:
1) If Bentham chips (a) to (d) were specifically Laclede primer paint on rust (which is very probable for many pretty good reasons), where are the strontium chromate crystals?
2) Is it a common phenomenon, that when the chips of red paints on rust flakes are heated up to 700 degrees C (heating rate 10 degrees per min), some shiny spherical/round objects are created from the rust („grey layers“)?
Whereas the first question remains basically unanswered, I have finally dediced to arrange some simple experiments, which can help to solve the second, pretty “important” question.
First, here is a repost of my contribution No 3491:
I just visited once again our yard and this time, I scrapped off using lancet only red paints from the rusted steel, from four independent sources, more specifically from some fence, some gate and two kinds of trolleys. Namely in the case of these trolleys, I would expect that the paint is a high quality primer, so perhaps with epoxy or alkyd binder. As for the red color, it can be caused by iron oxides, but can be also caused by lead stuffs.
Here is a photo of the chips, which were attracted with the magnet (about half of them). Then, I transferred them from the magnet to the beaker:
This tuesday, I asked Dr. Slouf from our Polymer Morphology Department to shot some photos of the chips shown above
(these were attracted with magnet, therefore, they are chips of paints on pieces of “magnetically active” rust). Here are shots at two magnifications, chips are placed on brass pedestal: (At the lower magnification, the viewing field is ca 10 mm, at the higher magnification, it is ca 1 mm)
As you can see, they look quite similar to Bentham chips:
(No wonder, all red paint chips can look quite similar, although they originate from different sources, should have different composition and could be applied using different methods -including electroocoating (for Senenmut
.)
You may notice that the rust layers are not well apparent above. It is just matter of playing with the photo. Here is a photo after a simple correction, using just function AutoAdjust colors in IrfanView:
Rust layers are already well visible, but other colors are not so realistic. This shows (among others), how easily can be the colors in micrographs changed and that it is nonsense to compare colors from various microscopes (to MM).
At higher magnification, nothing extraordinary. Just paint chips, like in Bentham paper or Millette study
Yesterday, I asked colleagues from the Department of Conductive Polymers to heat my “fine collection” of red/gray chips in their oven (I used this oven already two years ago for the heating of my Laclede paint imitation). They kindly heated my chips up to 700 degrees (heating rate 10 degrees/min, like in DSC experiments in Bentham paper. Looking just through magnifying glass, the most of chips were still red after heating, but generally darker.
Unfortunately, Dr. Slouf left for his holiday today, so I asked another colleague, Dr. Babic, who kindly microscoped my chips after heating. His microscope is not so good, but basically suffices. (For better photos, we have to wait some week or so. Dr. Babic again microscoped chips at two magnifications:
Here is a scale for the lower magnification:
It follows from this shot that the whole viewing field corresponds to 700 microns, since the distance between larger ticks is 100 microns.
Some photo of chips at this magnification is here:
After a closer look, some shiny round objects are hardly visible, but they are somehow resolved at 8x higher magnification:
And here is for comparison the “infamous” Fig. 20, Bentham paper
I would say that in all these photos, some shiny round objects (formed from the rust layers) are somehow visible. Therefore, their formation from red paints (or perhaps from any paint) on rust, when heated up to 700 degrees C, seems to be a quite common phenomenon
) My results so far are not conclusive (I have to wait for the better microscope), round objects in Fig. 20 from Bentham are definitely better "developed"). But I am quite sure that when looking really closely (with a better microscope), I would find the better "examples", it's just a matter of patience... For now, that's all, Dr. Babic was in hurry and had to left for the rest of week...
Thank you for your attention
(And many thanks also to my colleagues, which helped me quite a lot with these “groundbreaking experiments”)
(It would be interesting to measure XEDS of these round objects, we have necessary device in our institute, but I think there is hardly any doubt here: these objects should mostly originate from gray layers, like in Bentham paper And it does not really matter if the content of iron is higher in them because of some partial reduction).
