It's definitely not a plastic coating, I tried to scratch it with a DVM probe point.. no scratch but metal was taken off the metal probe onto the sample, so at least the surface is quite hard. I read the coating is supposed to be 16 to 18 mils thick, which is roughly 2/100 inch.. looks about right to me (the sample is only 1 inch long, the coating looks thicker because it's always cracked at an angle).
Interesting note, I read that the HRSI coating is a form of silicon carbide, *that* of course is very hard stuff. I don't think this fragment is TUFI, but I would like to know some of the characteristics of earlier tile used on the shuttle.
I'm about 30 miles from your former shuttle guy, it might be interesting to talk to him, but if the sample is far too heavy then it's probably nothing.
If the black coating is thick and hard, it's not HRSI tile.
PERIOD.
I think the best thing is to send it to NASA.
NASA again reporting as simplistically naive, and/or politically correct as possible, maybe those 4(?) astronauts took their gloves or helmet off because they were still alive and slowly burning to death in the long-intact crew compartment. That also would leave evidence that they had suffocated and not burned to death.
from FLORIDA TODAY By John Kelly
... "The report did not provide specific details about how the crew died or how long the seven might have survived, only that the compartment was intact for almost a minute longer than the rest of the ship.
In general, the report said the astronauts did not burn to death. They died from suffocation when the cabin did finally rip apart and from the force of colliding with other objects at incredibly high speeds as the wreckage fell to the ground.
The report also recommended future crews be carefully trained to wear all of their protective gear. The forensic review showed three of the seven astronauts were not wearing their gloves and one was not wearing a helmet. The report said, however, that none of that would have increased the astronauts' chances of surviving the Columbia break-up."