To all our iron casters what crucible type are you using? Silicon carbide, clay graphite, graphite, something else?
Clay graphite is the go: it withstands higher temperatures than silicon carbide crucibles and silicon carbide is soluble in molten iron too with a similar effect to ferrosilicon.
Hmm interesting. I read iron burns out graphite which had me a bit confused. But I'm guessing that is just incorrect info from random people on the internet. I'll have a look around for a clay graphite crucible.
Iron tends to devour pretty much everything, it seems. Seems it just eats silicon carbide crucible faster than iron-rated clay-graphites!
If you visit Morgan's website and look up some of the crucibles listed below you can see types like Himelt silicon carbide which is a premium silicon carbide crucible resistant to fluxes, it barely makes it to the molten iron range. When you read the blurb from the Himelt page it says: "Excel is intended for aluminium melting in oil-fired furnaces, melting copper-based alloys in gas-fired and oil-fired furnaces, melting precious metals and non-ferrous alloys in low to medium frequency induction furnaces. Himelt provides enhanced performance in those applications where more arduous service conditions exist. " Himelt is the 1400 deg C version of the Excel crucible 1250 deg C. Most good clay graphite crucibles have some silicon carbide added and most silicon carbide crucibles have some graphite added, it's just the ratios that vary.
I think they are the most versatile but if you don't need the higher operating temps there are more conductive higher performing materials. Best, Kelly
Morgan, Vesuvius, etc but what is it you want to do that cant be done with a clay graphite crucible? K
I bought an AX25 Himelt from the Morgan dealer as they'd run out of the normal silicon carbide ones, cost about the same price too.
Not sure, actually. It seems a question of what one can get one's hands on, if one is not a big-budget commercial outlet. Legend (Sparks, Nevada) largely has three or perhaps 4 flavors of crucible: their budget line, which seems short-lived, if talk is true; the Salamander; a carbon-bonded sorta-silicon-carbide; and finally, the true silicon carbide.
It's noticeably thicker than the clay graphite ones too, SiC should be more rugged and longer lived than clay graphite for aluminium and copper alloys.
True. I was originally thinking to use the budget crucibles for fitting purposes, so less weeping should I have an attack of The Dropsy and the pot ends up in pieces on the floor. Otherwise, once one has one's furnace, tongs, shanks, etc, then one goes to the more durable and costlier items...
There's no real standard for shape even among the same crucible manufacturer, so some bending and fitting is needed with each crucible. So a cheap crucible will be significantly different in shape even when the crucible seller tells you they're the same size.
