Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
 Pages:  1  
Author: Subject: Metal Shot Heating Bath
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 27-1-2016 at 22:27
Metal Shot Heating Bath


I have made a couple of attempts at creating a heating mantle and have so far been unsuccessful. So I was wondering what kind of metal shot might make a good heating bath. Copper has some attractive properties but is pretty expensive.... Would steel BBs make a good heating bath for use with mechanical stirring, or are they too large/not conductive enough? Also, what cheap and readily available shot might work well with magnetic stirring?

[Edited on 28-1-2016 by JJay]
View user's profile View All Posts By User
DutchChemistryBox
Hazard to Self
**




Posts: 74
Registered: 24-3-2013
Location: Strasbourg
Member Is Offline

Mood: No Mood

[*] posted on 28-1-2016 at 02:51


http://www.labarmor.com/lab-armor-beads-for-lab-water-baths/

I use those, you can request a free sample. If you ask a friend to request a second sample then you have more then enough for home use.

[Edited on 28-1-2016 by DutchChemistryBox]




View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 28-1-2016 at 03:59


Quote: Originally posted by DutchChemistryBox  
http://www.labarmor.com/lab-armor-beads-for-lab-water-baths/

I use those, you can request a free sample. If you ask a friend to request a second sample then you have more then enough for home use.

[Edited on 28-1-2016 by DutchChemistryBox]


"Starting at $1399" - I think I would definitely have to try a sample before making that purchase.

Their beads look quite a bit larger than BBs. So I guess BBs would probably work for thermal transfer, although they would tend to shift/roll around more than beads.
View user's profile View All Posts By User
Sulaiman
International Hazard
*****




Posts: 2901
Registered: 8-2-2015
Location: UK ... on extended Holiday in Malaysia
Member Is Offline


[*] posted on 28-1-2016 at 05:30


Also note that those beads are rated for -80 to +180 celcius.
View user's profile View All Posts By User
MrHomeScientist
International Hazard
*****




Posts: 1803
Registered: 24-10-2010
Location: Flerovium
Member Is Offline

Mood: No Mood

[*] posted on 28-1-2016 at 05:31


Those are extremely expensive for just being aluminum shot. I'd like to try making some by pouring molten aluminum into water. Would be a hell of a lot cheaper, if you have a furnace. I built one out of an old charcoal chimney and hair dryer.
View user's profile Visit user's homepage View All Posts By User
careysub
International Hazard
*****




Posts: 1339
Registered: 4-8-2014
Location: Coastal Sage Scrub Biome
Member Is Offline

Mood: Lowest quantum state

[*] posted on 28-1-2016 at 06:17


There have been a couple of threads on this recently, which I believe you read.

There are cheaper aluminum shot/pellet sources than LabArmor:
http://www.sciencemadness.org/talk/viewthread.php?tid=64259
http://www.sciencemadness.org/talk/viewthread.php?tid=64841

Look up the vendor "handi-ramp510" on eBay: 10 lb of aluminum for $50.

Aluminum conducts heat 5 times better than steel, and is 1/3 the weight.

There is also copper metal powder on eBay $52 for 4 lb (or $120 for 10 lb). Copper conducts twice as well as aluminum (but is also 3 times denser).

Prices:
Lab Armor beads: $100/Liter
handi-ramp510 pellets: $23/Liter
Copper powder: $178/Liter

I was just looking at a chem lab handbook about "metal baths" - molten low mp bismuth-lead alloys. The really low mp alloys all either have cadmium in them, which would make me wary of cadmium fumes, or indium which is really expensive.

Rose's metal with an mp of 98 C/208 F is the lowest mp alloy with neither cadmium or indium and is $340/Liter from Rotometals (its density is 9.7).

It occurs to me that combining the aluminum pellets with the copper powder might make a good substitute to using a liquid metal bath. The super-efficient conducting copper powder would fill the pellet void giving a boost to thermal conductivity in two ways.

Maximum random packing density for spheres is 64%. A mix of pellets and powder would be something like 60% aluminum pellets (assuming the squat cylinder pellets don't pack quite as tightly), 40% copper powder (copper powder is not solid, so it is something like 30% copper metal and 10% air).

This would make a dry bath costing $85/Liter, with a density of 4.3.

BTW - I don't think "shifting" is a problem with a bath. You would presumably clamp your flask in place, then pour in the bath beads.

[Edited on 28-1-2016 by careysub]
View user's profile View All Posts By User
MrHomeScientist
International Hazard
*****




Posts: 1803
Registered: 24-10-2010
Location: Flerovium
Member Is Offline

Mood: No Mood

[*] posted on 28-1-2016 at 07:07


A molten metal bath is an interesting idea. I've made some low-melting alloys (one liquid at room temperature, which I have a video on) so this would be cool to try. The problem, at least with alloys I've made, is that they usually wet glass. It seems like gallium is the culprit there, and possibly indium. So if your requirements allow you to use an alloy without these metals, it might not stick so much.
View user's profile Visit user's homepage View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 28-1-2016 at 08:05


I've considered using zinc pennies, but I'm concerned that they might melt on the hotplate.
View user's profile View All Posts By User
XeonTheMGPony
International Hazard
*****




Posts: 1492
Registered: 5-1-2016
Member Is Offline

Mood: No Mood

[*] posted on 28-1-2016 at 08:33


IMO being a one time investement with high resale value I'd just go with course copper my self (What I'll be doing personaly)
View user's profile View All Posts By User
careysub
International Hazard
*****




Posts: 1339
Registered: 4-8-2014
Location: Coastal Sage Scrub Biome
Member Is Offline

Mood: Lowest quantum state

[*] posted on 28-1-2016 at 08:44


Quote: Originally posted by MrHomeScientist  
A molten metal bath is an interesting idea. I've made some low-melting alloys (one liquid at room temperature, which I have a video on) so this would be cool to try. The problem, at least with alloys I've made, is that they usually wet glass. It seems like gallium is the culprit there, and possibly indium. So if your requirements allow you to use an alloy without these metals, it might not stick so much.


I forgot to mention, the lab manual prescribed coating the flask with graphite to prevent metal from adhering.
View user's profile View All Posts By User
XeonTheMGPony
International Hazard
*****




Posts: 1492
Registered: 5-1-2016
Member Is Offline

Mood: No Mood

[*] posted on 28-1-2016 at 08:45


IMO being a one time investement with high resale value I'd just go with course copper my self (What I'll be doing personaly)
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 28-1-2016 at 11:11


Copper pennies contain more than one cent worth of copper, but who has time to gather enough to fill a bath?
View user's profile View All Posts By User
The Volatile Chemist
International Hazard
*****




Posts: 1973
Registered: 22-3-2014
Location: 'Stil' in the lab...
Member Is Offline

Mood: Copious

[*] posted on 28-1-2016 at 13:55


Quote: Originally posted by MrHomeScientist  
A molten metal bath is an interesting idea. I've made some low-melting alloys (one liquid at room temperature, which I have a video on) so this would be cool to try. The problem, at least with alloys I've made, is that they usually wet glass. It seems like gallium is the culprit there, and possibly indium. So if your requirements allow you to use an alloy without these metals, it might not stick so much.

One could always use a container other than glass. Of course the cheapest alternative would be metal. Do gallium alloys alloy with metals like iron/steel when hot?




View user's profile Visit user's homepage View All Posts By User
chemrox
International Hazard
*****




Posts: 2921
Registered: 18-1-2007
Location: UTM
Member Is Offline

Mood: psychedelic

[*] posted on 28-1-2016 at 15:07


I would suggest using an electric lead melting pot with woods metal. Woods metal is a time honored mixture for heating glassware to high temperatures but be careful. I destroyed a heating mantle and warped a flask running an exothermic reaction. Check the thread on oil baths and consider sand.



"Ignorance is the Mother of Devotion." — Robert Burton.
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 29-1-2016 at 13:20


Apparently there are still lots of copper pennies. I am told that coin collectors regularly buy $25 boxes of pennies from banks. A few hundred copper pennies weighs a kilogram.... It just might be worth sorting through enough pennies to make a copper bath.
View user's profile View All Posts By User
Herr Haber
International Hazard
*****




Posts: 762
Registered: 29-1-2016
Member Is Offline

Mood: No Mood

[*] posted on 30-1-2016 at 11:14


I once had this idea and went to my local armory to get some copper BB's.
If I remember correctly, they cold me they were only copper coated so they would eventually melt.

Instead, they suggested I go find an armory that sells non lead shot (steel) because of ecological reasons many people are fighting against the use of lead.
I never pursued the idea, using ultra fine and pure sand from a quarry I have nearby but I guess different sizes of bird shot would provide good thermal conductivity and be a lot easier to cleanup.
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 30-1-2016 at 14:09


BBs are usually steel with a copper, zinc, or stainless coating.
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 14-2-2016 at 05:59


I decided to go with copper pennies. I can get $20 worth/day from a local credit union, and about 20% are copper. This is around 300 ml of pennies at around 1200 grams from $20 worth of pennies. Sorting them takes time, so I do it while running distillations.

20160214_045101.jpg - 899kB
View user's profile View All Posts By User
careysub
International Hazard
*****




Posts: 1339
Registered: 4-8-2014
Location: Coastal Sage Scrub Biome
Member Is Offline

Mood: Lowest quantum state

[*] posted on 14-2-2016 at 07:46


Quote: Originally posted by JJay  
I decided to go with copper pennies. I can get $20 worth/day from a local credit union, and about 20% are copper. This is around 300 ml of pennies at around 1200 grams from $20 worth of pennies. Sorting them takes time, so I do it while running distillations.


How big a fraction of copper pennies are you finding?

1982 minted both zinc and copper, are you sorting these by weight (though a few zinc in the mix is not exactly a disaster). (There are also rare 1983 pennies accidentally minted in copper!)

If you are buying pennies for this purpose presorted copper pennies are available from eBay.

When I did this from a relative's coin hoard I use a 0.1 g scale to sort the 1982, but found the situation a little more ambiguous than you might think. The minimum weight of a copper cent (new) is 2.98 g The maximum weight of a zinc cent is 2.60 g, And I found an even wider variation from wear (on the one hand) and oxidation (and possible other deposits) driving the weight up. Dropping the coin on tile helped in some cases.

I found about 1/3 copper but I think the hoard may have selectively enriched in copper.

Not that this is of great import, but it should be noted that the thermal conductivity of the copper penny alloy (5% zinc, some tin) is only about 2/3 that of electrolytic/tough pitch copper (the nearly pure copper used in industry) .



[Edited on 14-2-2016 by careysub]
View user's profile View All Posts By User
XeonTheMGPony
International Hazard
*****




Posts: 1492
Registered: 5-1-2016
Member Is Offline

Mood: No Mood

[*] posted on 14-2-2016 at 08:03


Seeing those pennies you'd be better off with the bb's
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 14-2-2016 at 08:28


Quote: Originally posted by XeonTheMGPony  
Seeing those pennies you'd be better off with the bb's


How so? The major problem with BBs is that they won't work with magnetic stirring.

I set aside the 1982 pennies and weighed them later. Zinc could cause problems at high temperatures, but it doesn't have to be a huge concern.
View user's profile View All Posts By User
subsecret
National Hazard
****




Posts: 426
Registered: 8-6-2013
Location: NW SC, USA
Member Is Offline

Mood: Human Sadness - Julian Casablancas & the Voidz

[*] posted on 14-2-2016 at 22:02


How about copper turnings/filings? They're a little expensive, though.

Take solid copper wire, and cut it into segments The smaller the better.

http://www.ebay.com/itm/PURE-COPPER-FILINGS-6-LB-BULK-BOX-GR...




Fear is what you get when caution wasn't enough.
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 14-2-2016 at 23:02


$10 per pound for copper is just outrageous.

I have seen penny sorting machines, but the ones that are ready to use out of the box aren't cheap.

I am still not exactly sure about zinc pennies that may have accidentally gotten mixed in.... Perhaps heating to 700 C and looking for molten blobs and destroying them with acid....
View user's profile View All Posts By User
XeonTheMGPony
International Hazard
*****




Posts: 1492
Registered: 5-1-2016
Member Is Offline

Mood: No Mood

[*] posted on 15-2-2016 at 10:57


heat distrobution and contact area the penny's contact area seems hidious., if you could grind them then that would be better but as flat discs.....
View user's profile View All Posts By User
JJay
International Hazard
*****




Posts: 3364
Registered: 15-10-2015
Member Is Offline


[*] posted on 15-2-2016 at 13:06


I'll try some stress tests.
View user's profile View All Posts By User
 Pages:  1  

  Go To Top