Change: Increased sintering temperature to 1150 (from 1100), increase presintering temperature to 1040 (from 1030).
This goes in:
This comes out:
So yeah. Not that great.
Interestingly enough, each bump up of temperature resulted in less shiny metal existing in the final product. I would have thought that, even if sintering didn't go correctly, it would have at least resulted in a puddle of metal at the end. But no. Hmm...
I did notice that my carbon at the end (reused) was more metallic slag than carbon, so maybe I shouldn't be reusing that. But I don't think that was the main problem.
I have a theory that my covering the crucible and doing the whole thing in one step is interfering with the thermal binder removal. After all, in the few commercial settings that choose to use thermal debinding (as opposed to solvent or catalytic removal in mist or liquid), they use a vacuum. Know what the opposite of a vaccum is? A sealed container! It's not quite truly sealed, but maybe it's interfering somehow...
So for my next attempt, I'm going back to attempt #1 with the exact original recommended temperature and holding settings and doing it in two steps again. However, this time I'm adding carbon in the first step where it's uncovered (can't hurt) and then adding more carbon and covering it in the sintering step. After all, I ended up with a cube, I just want it to be less oxidized... right?