proper floor type for casting steel and concrete hydrates?

[coppercone2]

What is the proper floor type to be used if molten steel is being cast?

Is dry (heated) concrete OK or will it dehydrate in contact with the molten steel if there is a spill?

Do you need to use high density firebrick just like the kiln walls or for a single small spill that may never happen will heated concrete thats degreased and laid out nice and smooth be ok?
I was worried about regular fire brick because i though its fairly pourous and it might absorb hydrocarbons etc, I am not sure how clean it needs to be to prevent a hydrocarbon vapor pop that spreads molten steel, copper, etc all over the place. A concrete surface on the other hand can be pretty much polished to a fine finish and cleaned nicely. I was imagining a post-hardening stressed concrete slab using stainless threaded rods going through vinyl tube to load the concrete after its settled to prevent any cracking.

https://en.wikipedia.org/wiki/Polished_concrete

I don't think you can seal it, so you would need to embed heaters in it to get it warm prior to use to clean it of water.

The idea would be to make a safe work area around a kiln which can be used to melt metal. And it would be covered with some kind of rubber matting material when not in use to keep it cleaner.

[chickenHeadKnob]

What is the proper floor type to be used if molten steel is being cast?

sand or dirt, accept no substitute

[coppercone2]

are you sure dirt is alright? I figure it might have organic matter in it that can decompose and cause the steel to bubble and splatter.

Sand is an option but its incredibly dirty. How thick of a sand layer would you need on the floor to work well?

Can you make some kinda sand bag out of some sort of plastic material that is known not to bubble up violently so you can lay down a floor before you work without all the cleaning? Some kind of low moisture content fabric?

I am guessing all these materials can end up spalling dangerously or are too hard to keep clean? If its not too thick then I can see some kind of sand bags working so long you are sure to wear soft booties over your kiln shoes so you don't destroy them. It seems reasonably storable if they are small.

Working in a litter box is not really tolerable :-/.. you would need to make a special vacuum cleaner to clean and store it when not in use.

[T3sl4co1l]

Green sand is used commercially.

Or something equivalent to that: even more often, resin bonded sand, usually a furan resin, but waterglass (sodium silicate) can also be used.

Green sand is >80% silica, so it is quite refractory.  The remainder is usually 2-5% bentonite, or up to maybe 15% of a less sticky clay.  So in turn, there will be a few % alkaline (flux) which reduces the melting point, but not enough to be a problem.

Green sand sticks together because of moist clays.  It must use the minimum amount of clay and moisture possible to hold its shape.  It must be porous enough that the moisture can find its way out through the material, not through the metal.

This is another good reason for resin bonded molds: there is no moisture, and the resin pyrolyzes quickly into less gas and a stronger matrix.  The best reason of course: resin molds can be rapidly produced, poured and broken up on automated pouring lines (yes, high-output foundry has been CNC for a long time, as most industries have been!).

I can definitely recommend you find a local foundry and take a tour.  There is likely one within a few hours drive.  It may be a small artisan studio (in which case nonferrous may be their medium -- Petrobond sand is often used here, or investment casting), it may be a smallish-turn industrial shop pouring iron or steel, it may be a full mass production line (in which case you might not be able to get a tour, oh well, keep looking).

Tim

[coppercone2]

your gonna make a foundary floor out of oily green sand? that would be a smelly and disgusting work environment.

I am not sure you understand what I mean, I mean the floor you walk on between the furnace and the mold. The work place floor. I also don't want to breath special loose refractory mixture, pouring a bunch out then cleaning it up is gonna be pretty dirty unless you use some kind of standard mesh filtered sand.. that stuff is bad for your lungs.

I just don't know the concrete properties well enough to make sure it does not de-hydrate the crystals when a pound of molten steel or copper hits it and make a big splatter which adds to unsafety in case the transfer crucible breaks, leaks, etc.

I want to know if there is a reasonable solution to do this in a work shop that has the capability to cast but does not necessarily dedicate to it. Some kinda sandbag seems OK but its still quite a bit of a work out to put the floor down prior to working. If I need to build a beach every time I want to melt some metal its gonna be kinda crazy.

The kiln-wall materials are fragile and its not suitable for a floor IMO. I wanted something clean and DIY. I am also interested in vacuum casting so working outside is not necessarily easy or desirable anyway because it looks like some serious hick shit if your neighbors see you pouring steel in a kiln suit. I am convinced the entire neighborhood property value would drop and someone might start playing banjo. Before you know it cars on cinder blocks are gonna be appearing in peoples yards, the mosquito population will increase and a tire shop is going to open down the street. I need to maintain order.

I have seen this logic applied before and I got the feeling myself when I saw an area where someone decided to leave construction equipment out in the open rather then build a shed. People start treating the area as some kind of industrial zone. I am not advocating a HOA but I really want a neat indoor solution if at all possible.

I would just put clean firebrick on the mold floor since its going to be on some kind of platform. Leave it covered when not in use.

[T3sl4co1l]

Oily, probably not.  But a lot of it will get around in a Petrobond shop, I can tell you that.  And that's not a bad thing.

In a greensand shop, they'll most likely spread molding sand, or loose (silica) sand.  Whichever.  The actual floor may be concrete or pounded dirt, no idea.

It would be unwise to discharge molten iron, or really anything melting above the boiling point of water (including solder, tin, pewter..), onto concrete.

Sand is perfectly fine.  It doesn't move out of the way, at least not from typical spillage amounts.  It's loose, it's not terrible traction (if sharp sand is used in a shallow layer), and most of all it's safe.

The problem with concrete is trapped moisture.  The concrete itself, or the aggregate, or the sand, contains trapped moisture (liquid water).  When boiled, this causes the material to spall (explode off in chunks).  That's NOT what you want happening, when some very angry metal is on top of it.

Concrete is unsuitable as a refractory too (even with suitable additives, like clean fine sand and perlite), because at a bit below red heat, it dehydrates, losing all strength.  At still higher temperatures, it shrinks considerably (sintering with the sand component), leading to heavy cracking and weakening.  Eventually it melts.  Sintering and melting occurs at an inconveniently low temperature (about yellow-white hot), due to the high lime content.

Tim

[Mechatrommer]

your gonna make a foundary floor out of oily green sand? that would be a smelly and disgusting work environment.

what do you expect? an air conditioned room with people wearing neck tie? try to get in line... you are doing something that can disintegrate flesh and bones..

[coppercone2]

i expected maybe materials engineering went further then litter box

i can't find anything about nice metalurgical research labs or anything, I don't really trust what heavy industry came up with to be the 'best' solution, usually casting is as economical as it gets and I am sure the entire industry will reflect that.

I wonder if a infrared reflective kiln liner paste would bring up a concrete slab to survivability but you would need to heat the whole thing to cure it. maybe with a roofing torch. and a thermally reinforced slab.

it looks like you would need to make some sand bags though.

[Mechatrommer]

i expected maybe materials engineering went further then litter box

it did, but i guess fancy materials will not be economical other than sand on the concrete floor. one of the idea is to avoid fallen molten steel from splashing onto living thing nearby, and that requires something "not rigid" that can take the kinetic energy, meaning something that you can not stand on to. if this for small scale diy, i think you can get by with just normal concrete floor, but be ready for the shiny cement layer where you stand on to "pop" exposing the sandy conrete layer below. meaning you need to keep maintaining your floor finishing if you want your work place to look tidy. ymmv.

[coppercone2]

if you look at how modern lab casting is done, you really don't have any splatter or anything like that. Some things will even have a ceramic solenoid under the melt chamber (i,e. vacuum induction melting), so that it is directly melted over your mold then a ceramic valve opens up and dumps it into the mold, so you don't need to do anything. Just monitor it from a far away EMO switch.

The stuff you see on the youtube videos is very very very cost sensitive if you see a giant cup moving around around with a buncha guys in kiln suits running around the factory floor.

It should not splatter or do anything funny in normal operation.

I also don't know how the porosity gas diffusion of the concrete will behave in a small spill. Can it still explode from only a few pounds of material or do you need a giant thermal mass ontop of it to channel energy into it to get a explosion?

I am worried the industrial guidelines for spilling 200LB of molten steel don't really apply to melting a few pounds.

[coppercone2]

in my mind I had something like this (maybe with a interlock so it does not pour when a bucket is not installed) and not The Deer Hunter. Most foundary practices I see are cringe worthy IMO. Forklift driving around a few feet away from a buncha guys running around a 50 gallon ladle of yellow hot steel...... 



I think people have a bad idea of how nice small scale metallurgy can look like.

[T3sl4co1l]

if you look at how modern lab casting is done, you really don't have any splatter or anything like that. Some things will even have a ceramic solenoid under the melt chamber (i,e. vacuum induction melting), so that it is directly melted over your mold then a ceramic valve opens up and dumps it into the mold, so you don't need to do anything. Just monitor it from a far away EMO switch.

Have you seen vacuum arc melting, for example?

You have much to learn, grasshopper...

I know a few guys in Los Alamos using vacuum induction melting on...unspecified...materials.  I didn't happen to ask if the material is known to splatter in the process, though.  (Would imagine it was pretty clean by that point, though.)

The stuff you see on the youtube videos is very very very cost sensitive if you see a giant cup moving around around with a buncha guys in kiln suits running around the factory floor.

Gosh, that's a big insult to the guys doing this for aircraft parts!

Not like turbine parts, I think those are vacuum induction and some manner of freezing (growth patterns) and heat treatments besides.  But anything that's not on the same bleeding margin, brackets, fittings, those can be made in very much this sort of way.

I also don't know how the porosity gas diffusion of the concrete will behave in a small spill. Can it still explode from only a few pounds of material or do you need a giant thermal mass ontop of it to channel energy into it to get a explosion?

Pounds?  Ounces!  Point a plumber's torch at the sidewalk some time and count the seconds to the first pop!

Tim

[coppercone2]

i showed you a video of what I mean, I don;'t really care what the aerospace industry considers economical. You can easily make a sealed ceramic valve thats opened by a piston that breaks a seal for instance and do a pour directly into a mold. Pretty sure you can do a pnumatic pump too if you get the right grade of expensive alumina tubing to prevent any kind of gravitational mishap with a traditional pour valve. This I would not recommend though because the last thing you want is a molten metal spray from some kinda shady refractory pipe work but it COULD be made safe if you engineer it right, because you would need to pressurize the system for a pour and you don;t have some fragile ceramic valve structure at the mercy of gravity.

I really think you are confused between small alloy research work and mass production here. I am not planning on running around with a hot crucible in some kind of crude lever system.

It would just slow down work alot because you can't take a sample while its hot to adjust the alloys, but in a real lab environment you would hopefully check the alloy contents with XRF to minimize the amount of tuning you need to do on the mixture.

[coppercone2]

and arc melting occurs on a water cooled copper plate inside of a vacuum chamber where you move a long electrode around with thick gloves or even a computer controlled system. What do you mean? It's pretty safe unless you get a plate breach which is why I would probobly use remote robotics instead of standing over a drum.

I would engineer something like a aimer for a pool cue for a remote controlled vacuum arc melt system, where you have two X-Y positioning grids and a single Z axis control to adjust the angle and depth of the electrode. Where the first grid represents your dominant hand the the second grid represents your non dominant hand which rests on the pool table. I think two joysticks would work nicely with a spring loaded foot pedal for depth.

[SeanB]

Small scale, get a load of fire brick and build a constrained platform for the area with brick and a steel frame. Spills will splatter anyway, the brick at least will prevent damage to the underlying concrete, which is more important. Otherwise just ordinary brick tile, with a very weak bonding to the floor, so you can replace the inevitable broken tiles. Large tiles are easier to lay, plus you can get end of run tile as part boxes pretty cheaply, unglazed tiles and just keep it clean. it will be ruined if there is a big spill, but little ones just clean it with a spade, and carry on till you need to change the tiles from too much crazing. You do not want glazed tiles, and do not bother to grout them either.

[coppercone2]

yea I was thinking about one that snaps together with magnets and stuff so you can clear up the floor space quickly and stow everything away on shelves when not in use. if its tiles I guess you could just use a fine dense sand to fill the seams between them prior to use (vacuum cleaner will make quick work of a few cups of sand but its different then dumping a 50 gallon drum of sand into something).

can fire brick absorb atmospheric hydrocarbons that will give it a problem from high temperature spills but not be handled easily by baking it in a oven prior to use? Can you get a (hydrocarbon vapor) steam explosion from that too?

some heavier hydrocarbons have a boiling point of 500C so your not likely to clean them up by baking the bricks in an oven prior to use like the water vapor. I am just unhappy with how pourous looking the firebricks I have are. I thought maybe to seal them with some kind of kiln paste to make a smooth surface that wipes down. it should work so long you bake them out real hot in a kiln. Maybe you can polish them afterwards too to make them more cleanable.


*tldr*

is the thermal shock performance of firebrick compromised by its pourous nature and the (dirty) nature of atmospheric gases? how can it be mitigated for surfaces that will be exposed to thermal shock other then liquid-water bake outs prior to use?

this might include storage guidelines and prep/cleaning procedures. Having to get an entire floor red-hot prior to laydown for a single pour would be expensive and annoying.

[rhb]

Buy these books:

https://stephenchastain.com/store/

they are excellent.

Whatever you do, do not pour molten metal on concrete floors or anywhere near water.  You can pour water on molten metal, but the other way around will kill you if you're lucky.

Read "American Steel" by Richard Press to get an idea of what a molten steel spill can do.

[chickenHeadKnob]

I would check your expectations if you expect to melt anything ferrous. I consider pig-iron or cast iron much more difficult to manage at all points in the process than something like aluminum/magnesium/silicon casting alloys. Learn on those first. I have done a few aluminum pours into sand molds back when I was still a teenager, it is do-able on the hobby scale. There are numerous aspects that can only be learned through direct experience. Mold and part design, sprue placement, shrinkage, fluxing, lots to go wrong.

I find your insistence of having a hygienic foundry exceeding humorous, it tells me you are not serious. While you may wish for an operating room clean foundry,  I have always wanted a bevy of beautiful  young women willing to cuddle-wrestle me all night long. I think we will both end up unsatisfied.

[rhb]

If you want a foundry inside your shop, leave a hole large enough for the furnace and molds, fill it with dry sand.  Then put a wooden cover over it when not in use.

[eKretz]

DO NOT pour molten steel on concrete. Listen to the advice you're being given. It might save your sight or your life. It only takes one accident. Fire brick doesn't have this "popping" problem for the exact reason that it IS porous. It's the trapped moisture in concrete that creates steam explosions.

[coppercone2]

its a bad analogy because women leave their crap all over the place. if you are a clean person and date a beautiful woman you will feel like her mom

try finding a women that will actually make a organized stand for her hygiene products, use the hamper or even get custom containers to hold the women things so the area is easy to clean. or have a 5S program in her purse and car. i ended up driving in a mobile dumpster.

[coppercone2]

DO NOT pour molten steel on concrete. Listen to the advice you're being given. It might save your sight or your life. It only takes one accident. Fire brick doesn't have this "popping" problem for the exact reason that it IS porous. It's the trapped moisture in concrete that creates steam explosions.

yea but what if you get something like some kinda heavy oil, dust, etc getting into the fire brick and turning it into a blind holes ? I don't like it as a shop surface because you can't verify if its clean easily. Something polished you can inspect optically prior to use without crazy procedures.

Based on what people are saying you need either a separate area or a well engineered floor you police and deploy when needed. It makes sense to me as a kiln surface where it gets to refractory temperatures slowly every time you use it, but not so much as something you end up walking on.

Can you take dense concrete firebrick, coat it with this stuff
https://www.amazon.com/ITC-100HT-Ceramic-Reflection-Refractory-Protection/dp/B01LWI8V0G

bake it, then diamond polish it to a fine finish and use that? that way it would be sealed and clean I think. Then you can just carefully wipe it down and inspect it.( on the top surface).If I can lay down a bunch of 'glazed' fire bricks and seal between them with clean dry sand in between use that is acceptable because sand use is minimal. Then I can glue them to floor panels which interlock with small amounts of fixture glue and keep the in a nice sealed cabinet while not in use along with a container of sand (something like those sandwich shop sauce bottles could dispense sand nicely with  bit of cab-o-sil or something). Like a jig-saw puzzle. Maybe even keep the cabinet gasket sealed and put one of those electrical humidity-remover panels on it (see bigclives analysis of one).

[SeanB]

Concrete spalls and pops because the heat decomposes it and releases the water bound up in the hydrated concrete. Ceramic that has been fired will not have bound water, and will be a mass of fused silica particles. The fire clay you are talking about needs to be fired to get it dry and sintered, driving out water of hydration, so just putting it on and not firing it will make it spall badly the first time you spill hot metal on it. Fire it and it will not spall, but will be very soft. Brick with just an edge, or high temperature fired terracotta is the only solution, unless you make as mentioned above a fire pit with crushed granitic gravel or such in it, that will both absorb molten metal and allow any steam to easily escape.

[coppercone2]

oh, that HT100 coating is going to be soft after fired? Its not like glazing porcelain where you get a nice glass coat after you fire it? (its what I imagined would happen)

I am guessing there are no glass-like surface coats you can put on top surface of fire brick that will work then?


edit:

What is 'brick with just an edge'?

[T3sl4co1l]

Cleanliness is rather redundant when all your ingredients are granular, and when high temperatures make everything "sticky" (due to fusion or diffusion).  Consider...

Say some rust flakes off from the burner or heating element, catches on that pristine white ITC-100 coating, and melts or diffuses into it.  Now you've got a black or brown stain.  (This is most dramatic in fuel-fired furnaces, where the usually somewhat reducing atmosphere ensures iron is ferrous Fe(II), which is "basic", a flux somewhat stronger than Mg -- often the spot ends up sunken in, as the refractory gets partially melted.)

Incidentally, in pottery: oxides are classed as basic, neutral or acidic.  The rules are broadly similar to aqueous chemistry: alkalines are basic (fluxes: Na, K, Ca, Mg..), nonmetals are acidic (B, F, Si, P..), ordinary metals tend to be neutral or basic (Al, Sn..), and transition metals cover the spectrum from basic to acidic, also depending on oxidation state (Fe(III) is sort of neutral; Fe(II) is definitely basic).

A "salt" has a low melting point.  CaO happens to have an extremely high melting point, in and of itself, and SiO2, very high; but the combination ~CaSiO3 has a much more modest melting point (liquid at molten iron temps).

Regarding transition metals, they can "salt" themselves even; this is magnetite for example: Fe3O4, better written FeFe2O4, ferrous(II) ferrate(III).  Other ferrites are well known for their useful magnetic properties...

The best refractories, in terms of reasonably high operating temperature, corrosion resistance (not just being neutral, but also rather insoluble in a glass melt) and strength, seem to be zirconia based (ZrO2).  Pricey though.  For example, bricks for lining glass holding tanks cannot flake or dissolve, and have to be in contact with corrosive Na-Ca glass for years.  I think they're usually _fused_ from a Zr-Al-Si mixture.  An incredibly dense brick like that, has basically no insulation value; they're backed by better insulators (Al-Si firebrick, or poured or rammed cements) to make the thing useful.  Wall thicknesses, of course, are in the fractional-meter range, for this reason.  Also, glass itself isn't very conductive, so all the more reason to have very good insulation.


Anyway... This, isn't a pursuit for the OCD, or the clean freak, or, uh, the hypochondriac I guess?  It can be done in immaculate, contained conditions -- but it's exponentially more expensive to practice that way!

I suppose it doesn't matter much -- I assume most of your questions are hypothetical rather than practical (I mean that you're asking about the possibility, not that you're actually setting up to do it right now -- at least most of the time).  So, it's still interesting to explore how much can be put into doing things in the various ways.  And then the later question becomes: if/when you want to give it a go, what level of that do you want to attempt, what are you capable of doing, how much budget do you need for materials and such, that sort of thing.

Tim