Furnace Refractory and crucible seasoning.

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ChipsAhoy
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Furnace Refractory and crucible seasoning.

Post by ChipsAhoy » Thu Apr 07, 2016 6:47 pm

Couple of quick questions:

In searching for refractory in my area, I've GOOGLED Kast-o-lite, Nexcrete and Dukast. I've found some distance vendors, any other brand names that would be good to search for? (Winter in Phoenix, 2400' to +/- 3000').

What is a standard (best practice, not exotic), way to season my #6 silicon carbide crucibles when my furnace is completed?

Thx

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steamin10
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Re: Furnace Refractory and crucible seasoning.

Post by steamin10 » Thu Apr 07, 2016 11:00 pm

Dry them first. If they have been stored in dark and damp basements, or in a cardboard box on a garage shelf, they may contain a lot of atmospheric moisture. In production, they fire crucibles enough to set them, and that
may be a problem. If in doubt use the kitchen oven to bake it off at 250 for 30-40 minutes, and them run it up to 500 for ten or 15. Have your furnace on low fire, and commit the warm crucible to the furnace that is just starting to warm up, and fire it off until you get a bright red heat. Go ahead and make your first heat or let teh vessel cool in the shut down furnace. clay graphite is spooky when hot, and a good lifting clamp is essential. Do not use a plyers on the lip, or anything like, it will go away on ya. At heat, these things get really spooky pliable. They also get ugly quick. They respond with the temps they are run at, doing small iron, you will be lucky to get 12 heats before the slag line goes through. about 30-40 for bronze, and I would be disappointed with less than 60 in aluminum. Do not mix metals, have a vessel for bronze, and one for aluminum, for example. Always pig the last bit of the heat, so you dont leave a skull to cool. It will encourage cracks from unequal cooling. An if you should lose your furnace in the middle of a heat, dump it. Leaving a nearly full vessel cool and harden, will just about guarantee it will split when the expanding metal reheats, as the cool vessel will crack like glass.

That is the best I can say, and it is cautious. When casting metals, make haste slowly, high temp burns are slow to heal.
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Harold_V
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Re: Furnace Refractory and crucible seasoning.

Post by Harold_V » Fri Apr 08, 2016 1:25 am

I used to use refractories made and sold by A.P. Green, but that was a long time ago. They became my choice because they had an office in my home town. They appear to still be in business.

I'm in agreement with Big Dave, although a silicon carbide crucible does not require any type of seasoning, which is unlike a graphite clay crucible. Preheating slowly for silicon carbide will do no harm, but it's necessary with graphite clay, as they are prone to cracking when heated rapidly because they have a propensity to absorb and retain moisture. Keep the added heat such that the crucible doesn't achieve a boiling temperature to ensure that no steam develops. Do that until it is quite dry. Once dry, they are quite forgiving.

Key to longevity is in not fluxing unless necessary. I used to melt cement silver in silicon carbide crucibles (I used a #8) and could get only six heats before the slag line penetrated the crucible.

Harold
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ChipsAhoy
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Re: Furnace Refractory and crucible seasoning.

Post by ChipsAhoy » Fri Apr 08, 2016 9:51 am

Looks like 1972 was a ... last banner year for A.P. Green.

Product Manufacturer Years Made
Therm-O-Flake L.B. Block International Vermiculite
Therm-O-Flake Coating (18% asbestos) A.P. Green 1963-65
Insblok 19 United States Gypsum 1970-71
Greencast 22 L GR A.P. Green 1970-72
Lo Abrade GR A.P. Green 1966-72
MC-30 A.P. Green 1966-72
Steelkon GR A.P. Green 1967-72
Steelplant Castable B A.P. Green 1960-72
Castable Mix 204 A .P. Green 1965-72
Greencast 97 GR A.P. Green 1968-72
Greencast 97 L GR A.P. Green 1967-72
Greencast 94 GR A.P. Green 1967-72

I think they are the current manufactures of Kast-o-lite.... still searching.

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Re: Furnace Refractory and crucible seasoning.

Post by Harold_V » Fri Apr 08, 2016 3:17 pm

I can't help but wonder if, maybe, the list you provided signifies when certain of their product lines were abandoned, as the tilting reverberatory furnace I built was constructed in the early 90's (could even have been the late 80's), and A.P. Green 94% alumina was the lining choice I made (of necessity).

Please do post anything you learn, as, assuming my plans for the future come to fruition, I will have need for more refractory.

Harold

Edit---that a vermiculite product was abandoned shouldn't come as a surprise, as it is common knowledge that asbestos is often associated with vermiculite.
Wise people talk because they have something to say. Fools talk because they have to say something.

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BadDog
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Re: Furnace Refractory and crucible seasoning.

Post by BadDog » Fri Apr 08, 2016 4:38 pm

Not common knowledge to me. We've used vermiculite for many years in a variety of contexts, and I don't believe (and am surprised) I never(?) heard that. Good to know...

I've been sort of following this topic (and others) as a blacksmith forge is somewhere almost to the top of my to-do list. It will almost certainly be a pile type forge built with refractory bricks (or cast slabs from a big propane heat exchanger lining) , but you never know what you may learn if you pay attention.
Russ
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ChipsAhoy
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Re: Furnace Refractory and crucible seasoning.

Post by ChipsAhoy » Fri Apr 08, 2016 9:59 pm

Out of 1,200 products manufactured by A. P. Green, 22 contained asbestos. A. P. Green removed asbestos from all but one product, Green PC, by 1973.In 1976 A. P. Green discontinued production of Green PC.

Products

Some of the known asbestos-containing products include A. P. Green Insulating Cement, SK-7 Insulating Castables, Green PC, Kast-O-Lite and Greencast.

In 2002, three RHI subsidiaries - A.P. Green, Harbison-Walker and North American Refractories Co. - departed from RHI and formed ANH Refractories Co. ANH still exists today and continues to manufacture and distribute refractory products.

I gleened the above from the net... Wasn't where I intended this thread to go, but I think this may be important info if anyone has old bags of this stuff around made before 1972... I think. Apparently it wasn't the end users that had problems but the folks who worked in the plants producing this stuff day after day.

BadDog:
I picked up a forge just the other day, dunno what I'm gonna use it for... but I got it!! Looks like "B" in the second picture. lol
Do you know of a refractory source near by? I'm down in Goodyear.
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BadDog
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Re: Furnace Refractory and crucible seasoning.

Post by BadDog » Fri Apr 08, 2016 10:37 pm

Yes, there is a local source for refactory bricks, seems like it was down off I17 around Indian School. I thought I had it in my shop supply contacts, but I can't find it right now.

Congrats on the forge. My plans are in the direction of an LP fueled forge, and I've already got most of the bits except the bricks, just need to allocate the time to finish it. Was supposed to do that this winter while it was cold. Yeah, sometimes that week. But other things came up and the Forge is on hold other than getting the 200 gal tank filled and mounting the high flow regulator to support the required BTU. Right now all it's doing is fueling my gas grill. Talk about over kill!
Russ
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