What's happened to my crucible?

[The Ignoble Troll]

The crucible was only a third full.
I have since bought a new crucible and done three further melts of silicon bronze and it looks like new.
However, I did those using propane and not the diesel burner which I know is way hotter.
I am still suspicious that the crucible was of poor construction.

Might have been poor construction, might have been the probable extra couple hundred thousand degrees


I was able to *boil* 3200°F refractory on heating diesel. Easily reached 3400°F cut with different solvents and oils.


You might want to use a plinth. I suggest a blend of alumina and hawthorn clay with enough chrome green to make the mix green


After firing it should be light pink and indestructible.

 

[creast]

Might have been poor construction, might have been the probable extra couple hundred thousand degrees


I was able to *boil* 3200°F refractory on heating diesel. Easily reached 3400°F cut with different solvents and oils.


You might want to use a plinth. I suggest a blend of alumina and hawthorn clay with enough chrome green to make the mix green


After firing it should be light pink and indestructible.

Thanks for the information.
I do have a plinth which is made from Arelcrete, a refractory concrete for furnaces and it is standing up well so far.
Your recipe sounded like a wizards mix to me until I looked up hawthorn clay as used in clay ovens but I am not sure what chrome green is?
Rich

 

[The Ignoble Troll]

Thanks for the information.
I do have a plinth which is made from Arelcrete, a refractory concrete for furnaces and it is standing up well so far.
Your recipe sounded like a wizards mix to me until I looked up hawthorn clay as used in clay ovens but I am not sure what chrome green is?
Rich

Cr2O3 chrome oxide. It's dark green but when the refractory hits the right heat the chromium will couple to the aluminum oxides rendering them pink like it does in rubies. Serves as an done-ness indicator as well, for some reason, I found it increased toughness. Or at least seemed to.

 

[creast]

Cr2O3 chrome oxide. It's dark green but when the refractory hits the right heat the chromium will couple to the aluminum oxides rendering them pink like it does in rubies. Serves as an done-ness indicator as well, for some reason, I found it increased toughness. Or at least seemed to.

Wow. Thanks for the clarification on that. Sounds a really useful refractory.
Cheers
Rich

 

[The Ignoble Troll]

No sweat. Cr2O3 makes a good abrasive as well, it is what makes green honing compound green!


Good luck with your next pour.