SAM4CH - 13-4-2007 at 14:51
If I can melt iron how can I make Silicon steel alloy which is very good at boiled H2SO4? How can I blance silicon percent and is it pure silicon or
silica?
12AX7 - 13-4-2007 at 15:33
Silicon. Silica is slag (which is present in certain specialty steels such as real wrought iron).
Either start with transformer iron (2~4% Si) or cast iron (thin sections such as radiators preferred), or add ferrosilicon. You'll probably need to
add some anyway, depending on the trade-off between workability and corrosion resistance.
Tim
not_important - 13-4-2007 at 16:33
I don't think corrosion resistant silicon-iron alloys are worked much, unless at red heat, but mostly is cast. Casting is all you're likely to be
able to do, but you'd better read up on the alloys you want first. You'll want at least 15% silicon.
http://www.corrosion-doctors.org/MatSelect/corriron.htm
http://www.sulfuricacid.com/documents/NorFalco_H2SO4TechBroc...
http://www.us.schott.com/tubing/english/download/kimax_corro...
Unless you're trying to do more than 20 liters in a batch, glass is the way to go. The lower concentration of acid you gave is tougher on the SiFe
than higher concentrations. And SiFe has been known to fail catastrophically when is use concentrating H2SO4, there's several embrittlement modes.
SAM4CH - 13-4-2007 at 23:11
if we talk about hastelloy, is it has good work in concentration H2SO4? what is the best trade? can we use coated hastelloy "thickness??!"?
not_important - 14-4-2007 at 00:12
If you talk about Hastelloy, which of the twenty or more of them are you referring to?
Have you read that H2SO4 pdf I gave the link for? It addresses some aspects of materials to use, nice graphs.
You are getting into chem engineering territory now. I've not worked with alloys like the Hastelloy family, so I don't know a lot of detail. I do know
that some extra care is needed in fabricating them, they are rather sensitive to carbon contamination which reduces their corrosion resistance and can
weaken them mechanically.
These alloys are somewhat expensive, and can be a bother to work with. How much acid do you have? Even casting silicon-iron doesn't pay back on
anything but industrial plant size operations, if you are doing that much you do not want to be asking hobbyists advice on how
to build such a plant, that is unless you're hoping to get your name in the press in the context of an industrial disaster. Don't cheap out on
building large scale apparatus, it's more costly in the long run. And I'm saying this as someone who has run reactions at 50 atmospheres and done hot
tube reactions at 600 C.
[Edited on 14-4-2007 by not_important]
SAM4CH - 14-4-2007 at 12:32
Yes, your files was very helpful,
I am working in concentration 35% H2SO4 becase we have Feasibility study in my country that it is cheaper than conc. acid.
I'd like to ask about simple and easy vessel "not pyrex" like coating lead on steel as you pdf that lead is good in five zones, and about NiCr alloy
can I use heating wire directly to ceramic vessel becasue it is more resistance for oxidation???
what about corrision rates of that alloy in pdf file for zones?
Can we boil acid in ceramic coated metal vessel??
not_important - 14-4-2007 at 20:05
When you say "35% is cheaper than concentrated acid" do you mean "costs less per liter or kg", or "costs less per mole of acid" ? Because if the 35%
acid cost per liter (or kg) is any more than roughly 1/3 the cost of the concentrated acid, the 35% is actually more expensive. I'm assuming that
this means you are importing the H2SO4,
Given what you've said, I'd say you're looking at industrial scale methods, and need to talk with an chemical engineer, preferably one with plant
design experience. Designing equipment on that scale is a bit different than doing it on lab scale, and there are economic tradeoffs in choosing the
best method that just don't arise on the lab scale.
I can say that matching a ceramic or glass coating to metal that is going to be run through a nearly 300 C temperature range is going to be a bit
tricky. Pinholes can be a problem, especially with ceramics; matching thermal expansion closely enough that the coating remains intact and adhered to
the metal will take care.
The solution is going to partially depend on the use of the acid, some applications can tolerate higher amounts of impurities from corrosion of the
container.
[Edited on 15-4-2007 by not_important]
Fleaker - 15-4-2007 at 07:32
What about plating a highly corrosion resistant metal on to say, copper?