DIY Carbon foam

[jeffreythe00]

Hi everyone. I just seen this in my subscription box and thought maybe some members can find some cool uses for this stuff.

I immediately thought it would make a great beam stop for continuous lasers but, probably not great for high powered pulsed lasers like ruby or yag. Still better than nothing I guess, even if its only one time use.

If you guys do anything creative, be sure to share!


Skip to 3:44 for actual tutorial.

 

[CurtisOliver]

Nice post Jeffrey. Seems like cool stuff. What would be amazing is if we could get visible light absorbing aerogel for beam stops.

 

[Benm]

Why would this be a good beam stop?

It's interesting stuff for sure, but you might just as well paint a brick black and be done with it. You don't want thermal insulation from a beamstop, and i think you could actually burn a whole through this material over time as it doesnt conduct the heat, so has to either radiate it off or evaporate.

 

[jeffreythe00]

I suppose the ol'e brick always works and is probably way cheaper and convenient. I just thought a more DIY solution would be fun. I didn't really give heat dissipation a thought. I guess you wouldn't want to heat up the carbon to something like 1000 degrees or it would just burn/melt/heat everything around it. I just imagined this as a fun hack for us laser hobbiests. "Hey, that beamstop over there is actually just burnt bread".

 

[Gabe]

So happy to see AvE pop up, he's my favourite YouTube channel by far. This could be great for people who do a lot of casting and go through crucibles like crazy and don't want to buy a bunch of graphite crucibles. I can't thing of much use for it in the laser hobby, pretty much all of what we use stays as far away from insulators as possible

 

[Benm]

It could be fun to do experiments with though.

I reckon it's one of these things that will dissipate up to some power level for a very long time, but once you go over that level it cannot take the heat away and will start to burn and a whole will be poked through.

Also commeting 'that beamstop is toast!' after succesfully aligning a laser etc would be quite funny

 

[Gabe]

It could be fun to do experiments with though.

I reckon it's one of these things that will dissipate up to some power level for a very long time, but once you go over that level it cannot take the heat away and will start to burn and a whole will be poked through.

Also commeting 'that beamstop is toast!' after succesfully aligning a laser etc would be quite funny

Yeah like he showed its not conductive in the thermal or electrical sense, so it wouldn't really dissipate the heat just absorb it, and since it's carbon its melting point is really high. lol I like that, because it's so literally true.

 

[Cyparagon]

This could be great for people who do a lot of casting... and don't want to buy a bunch of graphite crucibles.

They're like $10 on ebay. The fuel, equipment, and time to construct one out of bread is well over $10, and will yield a vastly inferior product. How are you going to form bread into a leak-free cylinder to begin with?

 

[Gabe]

They're like $10 on ebay. The fuel, equipment, and time to construct one out of bread is well over $10, and will yield a vastly inferior product. How are you going to form bread into a leak-free cylinder to begin with?

Overestimated the cost of graphite crucibles, my bad. Iunno, maybe pack it into a cup shape in an offcut of tubing. The super-toast didn't seem too misshapen relative to normal bread, I think it might work. Might be tough to get it out without cracking it, though.

 

[Benm]

Yeah like he showed its not conductive in the thermal or electrical sense, so it wouldn't really dissipate the heat just absorb it, and since it's carbon its melting point is really high. lol I like that, because it's so literally true.

I think it would actually just burn in air if heated with enough laser power.

Torches and such cannot heat something to a temperature above their own, but lasers easily can, and there is no real limit to how high that can go given enough power.

Also, something like an oxyacetylene torch is not the best thing to burn materials: the reaction that powers the torch uses up a lot of oxygen leaving very little to combust whatever you are trying to set on fire. This can be remedied to some degree by running the torch lean, but with laser heating the full 21% oxygen from the air would be available.

 

[Gabe]

I think it would actually just burn in air if heated with enough laser power.

Torches and such cannot heat something to a temperature above their own, but lasers easily can, and there is no real limit to how high that can go given enough power.

Also, something like an oxyacetylene torch is not the best thing to burn materials: the reaction that powers the torch uses up a lot of oxygen leaving very little to combust whatever you are trying to set on fire. This can be remedied to some degree by running the torch lean, but with laser heating the full 21% oxygen from the air would be available.

That's very well possible. How much power do you reckon? High CO2 laser range?

 

[Cyparagon]

No, this wouldn't work as a beam stop for anything class 4. The insulative properties mean the material that meets the beam would get hot enough to burn away because so little of the heat is transferred away. The irradiated spot would turn to (white) ash over the course of a few seconds or a few minutes.