Ceramic paste

Hi all,

i tried with ceramic- and glass-powders mixed with different solvents and pastisicers (with different and not so brilliant results) - but i'll try again as this would be very interesting for fabbing highly rigid and heat-resistant parts ...

Here in the fab(at)home-groups is maybe some interesting discussion (and some hints) too: [groups.google.com]

Viktor

why doesn't just clay by itself work? I understand that it takes a lot of force to squeeze out the clay, but with a plunger system i think it might work. once my Darwin is upa nd running i'll take another look unless i am told that another direction is more promising.

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Jay

Hi Jay,

... it works fine for extruding thick trays in some millimeters diameter.

But when reducing the hole in dispensing needle down to 0,3 or even smaller (i need 0,1 for some structures), then it tend sticking too.

I'm testing with different solvents and additives for reducing the friction and the sticking, but then the amount of solidus is beneath 50% and you have much more shrinkage, so i have to battle with form-accuracy and shape-distortion ...

Viktor

Oh, ok, that makes sense. I guess that the actual granule size of the might factor into its "stickiness" problem when the extrusion size gets that small.

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Jay

I found some stuff on t'internet that sugests using pasta dough.

They tried a range of food stuffs and pasta dough turned out the best.

Cheap too.

I think you will find the stuff (MIT did it) if you google Faberoni

cheers

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

Pasta dough... also fully degradable... Reminds me of the article about starch plastics: [www.instructables.com]

Howie

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--
Airspace V - international hangar flying!
[www.airspace-v.com] for tools and toys

The thing with pasta dough is it is only good as a support material. You can't make a engine with pasta dough.

But, extruding pasta dough demonstrates that you can extrude granular media with a syringe extruder. Maybe something in the dough makes it easier to extrude?

Reprap really needs to extrude true ceramics, as reprap is currently having melting problems. Just think of when reprap starts to extrude metal. You can't have a reprap made of plastic for sure!

Don't forget, you can also make engines out of ceramic, even jet engines: [www-rpl.stanford.edu]

In other words, it might be possible to reprap a flying car!

Good point!

My buddy and I have been looking into machinable ceramics as a first gen try at aluminum extrusion. Plasics are horrible for this sort of thing. We wanted to first replace the PTFE barrel to get to higher heats. Most machinable ceramics--we are finding--is pretty porus which is no good for pushing plastics or other molten stuff through. Maybe extruded ceramic is a better idea. Especially if it brings us flying cars!

Demented

Almost forgot, does anyone know any ceramic formulations?

If you look here you can find a few on 'robocasting' by some Sandia people:
[www.google.com]

One paper mentions 'alumina powder, water, and Darvan 821A as a dispersant'.
(60% solids).

===========================
Later on some people in the Colloids Assembly Group at University of Illinois at Urbana-Champaign people start playing around with various agents to turn the material into colloidal gels and stuff.

Direct Ink Writing of 3D Functional Materials*
[colloids.mse.uiuc.edu]

There are lots of publications here by the "Colloids Assembly Group"
[colloids.mse.uiuc.edu]
(Note:earlier pdfs on that site have borked urls, delete the word publications from the path if you get a 404 when clicking on a link.)

Interesting stuff, like 'Alumina

Hey guys, I just did a basic search on YouTube. Have a look

[www.youtube.com]

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Jay

[www.youtube.com]

There's also the option of impregnating a porous ceramic object with uncured resin. then curing it.

So a two step process fab a ceramic object (porous is good) fill it with resin, not as hard as it seems if you get pore size and viscosity suitably matched it should wick the resin up.

Then cure (thermoset resin perhaps).

The final result will be as good as a filled plastic. (Usually very desirable)

The pasta dough was of more immediate interest as a cheap support material but the point as to why does it flow is well taken. I actually have no idea. Maybe it's because the granules are softened by the water/liquid in the dough. Flour generally turns to mush.

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

Hey, if you can adjust the pore size to really small, you could print out water filters. Maybe even reverse osmosis filters.

Well, from watching some cooking shows, I just learned that pasta is more like a gel then a granular media.

Pasta is virtually entirely starch. IIRC, when you mix starch in water you get a colloidal solution, which is that gel you are talking about.

While at university, I worked summers in a factory that made starch and sugars from grain sorghum. Most of the processing kept the starch in a water mix. As long as you kept it moving or agitated things were fine. The moment it was allowed to sit, however, you wound up with most of the starch forming a colloid gel at the bottom of a tank that had about the consistency of tofu.

Whenever we lost power and the pumps and agitators shut down for more than a veryfew minutes we'd spend a couple of hours blasting the gel out of the system with high pressure water.

The Robobuilder machine looks very much like some stuff I think Adrian mentioned.

The guy that was working on them was wanting to be able to print buildings. Essentially using a v Large Moving Gantry Cartesian at each site and a concrete/slurry mix.

You will notice that the extruder is extruding what looks like standard clay but has a troweling attachment on the side of the nozzle. This is what gives the smooth face on the outside and lack of a troweling attachemnt on the inside of the piece leaves you with a ridge at the intersection of each layer.

The troweling attachment is pretty cool for larger structures but does limit the internal radius of the external wall to what you can get the troweling attachment into and out of again.

The main websites for this guy are linked of :-

[www.lboro.ac.uk]

Which was a link Adrian sent me.

Cheers

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

While I hadn't heard of Dr Rupert Soar's work, (Andy's link), it looks interesting.

Jay Swift's video of the clay (cement?) depositing machine happens to be from Dr. Behrokh Khoshnevis at USC:
[www-rcf.usc.edu]
[www.contourcrafting.org]

Khoshnevis has an interesting approach to powder-bed 3D printing. Instead of using a laser to sinter material, he sprays down a sintering inhibitor as needed, and then fuses the material using a bar heater*, like a nichrome wire. Much cheaper than anything with a laser, and it's a lot faster to pass a bar over a surface than raster across it with a point.
[www-rcf.usc.edu]

He has a paper here:
[www-rcf.usc.edu]
It's very clear and straightforward read.

*He mentions that the heater can consist of individualy powerable subzones, to avoid unecessary heating.

I think the one that jumps out for me from Sebastiens links is:-

Fabrication of Piezo Electric Actuators using Contour Crafting

Given that we have been discussing ultrasonic welding as a possibly (possibly not) useful technique.

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

Your kidding me! High frequency piezoelectric actuators are the most expensive part needed for metallic extrusion!

There is only one problem with ceramics, they need to be fired in a specially controlled kiln.

not exactly. I mean there are pots, i think that they are coined earthware, where the clay just air dries. Wha makes the ceramics hard is that they become partially glass after firing, and any glazes are completely glass. If you were to say, create a heater barrel out of ceramics, all you have to do is wrap the clay in whatever you are going to be using to heat it and heat it. Yes, you will want the clay to withstand higher temperatures then whatever you will be melting, but pottery has been fired at all sorts of temperatures throughout man's history. If worst comes to worst, dig a whole in your backyard and fire the clay in a pit.

Sorry if that turned into a rant. It was just supposed to be informative.

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Jay

On kilns

you might want to have a google for Top Hat Kiln and also kilns generally.

They are not hard to temporarily stack together out of fire brick and swaddle in glass blanket.

Heating is also easier than you think, considering the temperatures that Nichrome will work up to.

Heater control is very easily achieved using an arduino board and some trivial circuitry particularly if you use burst control.

Folk in the african bush can do ceramics without half of the technology we find commonplace.

Push comes to shove blag some space/time in you local school/technical colleges pottery kiln.

more thoughts.

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

I've gone to a local brick yard and they have let me put some pots in with their bricks, so if that seems sensible for your area...

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Jay

I am talking about printing out technical ceramics, which require a bit more than just fire and dirt.

And apparently, small electric pottery kilns can be converted to make high grade technical ceramics(superconductors), so I guess this solves the problem.
[www.webcom.com]

Heres some information on making high temperature superconductors, for all who are interested in the specialized processes needed for technical ceramics.
[www.webcom.com]

I wonder if my college's art department would let me "borrow" their kiln for firing some test prints.

Probably if you convinced them you were going to upgrade and calibrate it for them for free....

Have you made burst firing controllers before ?? (They are dead easy when you know how)

aka47

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Necessity hopefully becomes the absentee parent of successfully invented children.

Anyone have any experience with bisque alumina?

[www.smallparts.com]

It sounds like it can be machined and used as-is or, alternatively, machined and fired at 3100

Hi Steve,

i tried with machineable ceramics from Dotherm: [www.moeschter-group.de]

Some tech-specs here: [www.do-ceram.com]

And with milling soap-stone: [forums.reprap.org]

Viktor