Sub-zero treatment

OK Mr Shepherd,You've got my attention!Since I'm not a chemist could you give us the run down on making your own Dry Ice ?I would really appreciate this one . Thanks in advance
 
Wow! :cool: I almost feel,-well-,"Dumb".I never realized thats what Dry Ice was made from.You are correct in your "simple"statement.How does that work out economically?Thank you very much for the enlightenment.
 
Danbo,Even the best comercial freezers won't get low enough to convert the austentite.It will be beter than no cold treatment,but it won't get it to the -70 full conversion area.
Stacy
 
It takes about 870 pounds of pressure per square inch to make dry ice. Dry ice is solid carbon dioxide. So, C02 gas is put under pressure to make it a liquid, then a solid. CO2 sublimates when it cools, meaning that it will go from the solid phase to the gas phase without becoming a liquid, hence "dry" ice.

I found a product (I didn't buy it) that will make sort of a dry ice "slush" but I don't know if it is as cold as solid dry ice. Find it here: http://www.frost-stick.com/#makeice . You need a CO2 canister, of course, but they range from $50-$150, it looks like, depending on which model you choose. You can also see some other options at http://www.dryiceinfo.com/mfn.htm .
 
bladsmth said:
Danbo,Even the best comercial freezers won't get low enough to convert the austentite.It will be beter than no cold treatment,but it won't get it to the -70 full conversion area.
Stacy
Click to expand...
I think it was a joke... ;) :D
 
Trust me, the stuff from the medial supply place makes dry ice--depending on the size CO2 tank, I'd say I get about 8-10lbs of dry ice/tank ( the long, thin ones) ...and if I dont use it, I'd say my tank lasts for atleast 6 months.
It's cheaper than buying a large dewar for LN. ALso, LN has to be special orderd where I live, so we're talking the added BS of waiting a couple of days.
 
OK,so I didn't look at the icon at 6AM.I didn't think he really ment it.However,a lot of people (ever read Ed Fowler's old HT receipe) think the freezer will do the job.
 
Ok, this is my opinion--------
Call the guys at Crucible, they've spent more money than I have doing research on their steels, if they say a freezer is good enough, thats good enough for me.
 
I would assume that the metallurgy texts would be correct on this one. Sure, anecdotal evidence is cool ("It SEEMED a lot better after a week in my freezer") but I assume the people who developed cryo methods did so through some sort of advanced pre/post analysis of the metal and determined what is happening and at what temperatures. The dry ice makers that Shepherd and I posted are so cheap it seems like a no-brainer. Heck, maybe I'll even get one, and that's REALLY saying something! :D
 
Your home freezer goes to -10F at best, Crucible recommends about -100F .While -10 reduced retained austenite it's not considered enough at least for the complex steels .-100 is considered satisfactory .-300 is satisfactory but added benefit below -100 is questionable at this point.
 
Whats kind of the - tempertures can you acheive with dry ice??

Shepherd, do you have one of those gizzmo's like you posted and how long does the dry ice last, doesn't it take several hours of sub zero soaking to be beneficial.

Thanks,

Bill
 
That's a good question... Are you sticking it in a cooler, then into a freezer, too, just a cooler? Adding acetone? What's your full cry procedure, I guess?
 
B . Buxton said:
Whats kind of the - tempertures can you acheive with dry ice??

Shepherd, do you have one of those gizzmo's like you posted and how long does the dry ice last, doesn't it take several hours of sub zero soaking to be beneficial.

Thanks,

Bill
Click to expand...
I have -the gizmo thas a nozzle with a bag you put on the tank.
I bought the best cooler I could find, but one that does not have a airtight latch ( It would dangerous if it latched tight, due to the pressure increase in the cooler) I was told a good 4hrs should do the trick. Depending on the cooler you might have to check to see how much life you ger out of your ice.

Sean
 
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