Sciencemadness Discussion Board - Hotter alternative for Kanthal ?

Hotter alternative for Kanthal ?

metalresearcher - 12-12-2020 at 23:48

I use an electric furnace for copper melting or other metals, but when I need higher temps, I have to use a propane furnace. The latter is much more energy inefficient.

One alternative can be iridium wire which can be heated in air up to 2000 C, but it is sooooo expensive.

Are there higher temperature affordable alloys for restistance wire ? I guess Kanthal alloyed with Mo or W ?

Sulaiman - 13-12-2020 at 03:53

silicon carbide https://www.google.com/search?q=high+temperature+heating+sil...

metalresearcher - 13-12-2020 at 06:51

Quote: Originally posted by Sulaiman

silicon carbide https://www.google.com/search?q=high+temperature+heating+sil...

In the meantime I found this SiC alternative as well.

https://www.kanthal.com/en/products/furnace-products/electri...
http://heatingelements.isquaredrelement.com/category/starbar...

But that is not feasible for amateurs, it cannot be simply and straightforward heated up by applying voltage to it, unlike Kanthal.
It has a much higher resistance at lower temps (< 1000 C) than at operating temps (> 1000 C).

It is more suitable for industrial applications.

rockyit98 - 13-12-2020 at 12:58

Kanthal can be used to melt Cu. but need thicker and longer wire to lower the temperature different between heating element and the thing you need to heat ,because thinner wire need large temperature difference to radiate the heat generated by the given length of wire. or lower the power of the element using triac dimmer at higher temperatures . I brought 75gms of 1mm diameter wire for a price of 100$/kg for that i just read this hand book just hours ago. i suggest you should read it.

Attachment: KANTHAL HANDBOOK.pdf (1.3MB)
This file has been downloaded 1183 times

[Edited on 13-12-2020 by rockyit98]

yobbo II - 13-12-2020 at 16:18

There is also Molybdenum Disilicide. It can go up to 1800C

https://www.ebay.co.uk/itm/Super-Kanthal-Element-6-12-1800/2...

Also called super kanthal (dont mix up with kanthal wire).

There are others.

http://www.sciencemadness.org/talk/viewthread.php?tid=70334

Yob

[Edited on 14-12-2020 by yobbo II]

macckone - 13-12-2020 at 16:56

Kanthal A1 can melt copper but as previously stated you need heavy gauge wire and it is not as efficient as propane or oil burners.

Molybdenum Disilicide (Kanthal Super) is higher temp as yobbo stated.

Next beyond that is going to be carbon or tungsten arc furnaces.

And finally induction and microwave furnaces.

Carbon arc furnaces can melt tungsten and pretty much anything else.
Induction and microwave furnaces can vaporize carbon but each has their own set of 'receptive materials'.

metalresearcher - 14-12-2020 at 13:05

Quote: Originally posted by macckone

Kanthal A1 can melt copper but as previously stated you need heavy gauge wire and it is not as efficient as propane or oil burners.

Molybdenum Disilicide (Kanthal Super) is higher temp as yobbo stated.

Next beyond that is going to be carbon or tungsten arc furnaces.

And finally induction and microwave furnaces.

Carbon arc furnaces can melt tungsten and pretty much anything else.
Induction and microwave furnaces can vaporize carbon but each has their own set of 'receptive materials'.

Well, using a fuel (gas or oil) fired furnace uses lots more energy to melt the same amount of copper, but in a shorter time, unless you have an 8kW Kanthal furnace.
Lots of energy gets wasted by heating the useless N2 in air and venting lots of heat off. An electric furnace (induction of resistance) are steady and can operate in a closed space.

rockyit98 - 15-12-2020 at 04:55

Quote: Originally posted by metalresearcher

you can make heat exchanger and preheat air with the exhaust , BUT only work with charcoal and also need high temperature tubes made from Al2O3 or MgO at the hot end, then copper in the middle and Al at cooler side. i made one that worked so well it even condensed water from exhausts while melting cast iron. i used coconut shell charcoal which have low ash (0.1% to 1% w/w).15 $ for 50 Lb bag.

WGTR - 15-12-2020 at 11:59

How much copper will you melt at one time? After it’s molten what will you with it? Pour it into a mold?

If it’s a large amount at once it’s probably more practical to heat with gas. Otherwise you can use Kanthal to provide bulk heating and use a more exotic material for an inner “hot zone”. Think about how a light bulb filament is very hot, but the bulb is only warm. Same concept.

If you use a vacuum or inert gas then tungsten is also a possibility, again with Kanthal providing most of the heat.

macckone - 15-12-2020 at 13:02

You can use a heat exchanger with propane or oil fired furnaces.
Industrially this is common. Many home heaters also do this.
You probably can't do an efficient heat exchanger for home use unless you are using fire brick like a kiln.
Many kiln designs use heat exchange to preheat the air.

rockyit98 - 16-12-2020 at 09:47

Quote: Originally posted by macckone

You can use a heat exchanger with propane or oil fired furnaces.
Industrially this is common. Many home heaters also do this.
You probably can't do an efficient heat exchanger for home use unless you are using fire brick like a kiln.
Many kiln designs use heat exchange to preheat the air.

not at very high temperatures, the gas mix self ignites at the heat exchanger and not at the kiln.in industries i think they heat the gas and air separately and also use much stable and cheap methane (CH4) rather than much more expensive and less stable propane or butane.