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Melting bronze

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10ba12ba02/08/2020 19:47:36
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I have quite a lot of bronze off cuts, too small to be of much use to me. I also have a heat treatment oven, well capable of melting it. I have successfully used graphite crucibles in this oven but they seem to only last for one melt. I don't need to pour the bronze into a mould.

So I'm thinking of using some mild steel channel (good draught angle) with plate welded on each end and melting the bronze in this, letting it go cold, knocking it out of the channel then cutting it up into bits that I can use.

Question is, will the melting bronze stick to the mild steel channel and if the answer is "yes", how can this be prevented?

H.

Ady102/08/2020 19:57:20
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4162 forum posts
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They used to paint foundry moulds with a liquid...

colloidial graphite??

can't 'member, sorry

Bazyle02/08/2020 20:47:55
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If bronze doesn't stick to steel how does brazing work. surprise

As it is just a simple shape a very crude sand mould would do.

David Davies 802/08/2020 20:53:13
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146 forum posts
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I can't answer your question directly as I have only cast bronze into sand moulds. l coated my skimmer and stirrer with "ladle paint" which prevented th bronze from sticking to the tools. It is available from all good foundry equipment stockists.

I have used your angle iron with end plates method many times when recovering lead.

hth

Dave

spelling!

Edited By David Davies 8 on 02/08/2020 21:13:21

Bazyle02/08/2020 21:59:27
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Whoops, brazing uses brass not bronze, though I expect it is an option.

Paul Lousick02/08/2020 23:36:08
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If the bronze does stick to the steel crucible, it will only be a thin coating. The rest of the molten bronze will pour out unless you allow it to solidify. The bronze lining will prevent the steel from rusting and be clean for the next melt.

Paul.

Hopper03/08/2020 00:34:27
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Posted by Bazyle on 02/08/2020 20:47:55:

If bronze doesn't stick to steel how does brazing work. surprise

As it is just a simple shape a very crude sand mould would do.

Unless you use Sif Bronze rods. But even then the steel has to be tested to about dull red to get the bronze to stick to it. Not sure how cold steel "die casting" would go though. The heat of the large quantity of bronze would certainly warn the steel up some.

Alan Charleston03/08/2020 07:08:13
103 forum posts
20 photos

Hi,

I used to work in a factory which had a glass furnace. The flow rate of the glass was checked by running it into a steel container over a timed interval and weighing it. A sheet of newspaper was placed in the container first, and it burnt out leaving a layer of carbon between the molten glass and the steel which stopped the glass sticking to it.

Regards,

Alan

JasonB03/08/2020 07:30:06
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I seem to recall that leaving molten metal in a crucible to cool can cause damage, this may be why your Graphite ones are suffering.

You would do better pouring the bronze into a steel container as it's unlikely to bond to that whereas it could well stick to your proposed steel crucible as the steel will be a lot hotter and any carbon applied to the surface unlikely to stay there during melting.

Adrian R203/08/2020 09:32:38
77 forum posts
8 photos

I melted some scrap copper once and poured it into a "non-stick" thin steel yorkshire pudding tray. This approach had worked fine for aluminium but the copper stuck so well that I ended up cutting the tray into segments and then grinding the steel remants off. Not recommended!

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