graphite for a frying pan bottom?

Provided you haven't processed anything nasty on the graphite, yes.

Steve

You are made of carbon, no? So, merrily munch away, bro.

I bought a slab on ebay, I have no idea what's been on it... Should I sand it down maybe? I've never even seen a chung of graphite before. Is graphite "dave's insainity sauce" proof?

-Scott

Did you ever hear of the Pyrolytic Graphite lined pipe for smoking pipe tobacco?

Released in the 1970's and the graphitic element wa made by SuperTemp in California?

Seasoning of a cast iron pan produces a high carbon content grease layer on the inside and you can cook over it.

You can even cook over a charred layer in a metallic pan, or a charred grill in a BBQ. You would then be cooking on carbon.

Bulk carbon isn't something that your body readily digests.

Great info thanks! Never heard of a Pyrolytic smoking pipe. Sounds like it would offer a smooth smoke. I'll have to make one (out of the polycrystalline slab I bought).

Do you recall when pyrolitic graphite became known or sold as such? Are all "Pyrolytic" graphites grown using CVD?

Thanks Jim!

Scott

In the 1950's there was considerable interest in pyrolytic graphites for rocket and missile uses.

Pyrolytic graphite is much older than that, but probably had very little commercial use.

I believe it is correct that the convention is to use the pyrolytic grphite term to denote many of the graphites made by means of CVD, but you can make carbon products by CVD which aren't commonly called pyrolytic graphite.

Hey Jim,

I did a google search on the Pyrolytic Graphite pipe you mentioned. I still have a couple questions that my search didn't answer. I'm not sure how the PG is encorporated into the pipe. Would the "bowl" (eh hem.) be made out of the stuff, or would it be the stem or both? I'm having difficulty imagining the geometry of either a bowl or a tube because PG is layered in 2 dimentions, not three. You said they were lined with PG. The only geometry that would make sense is cylindrical. Did they make a real thin sheet or foil of PG and wrap it into a cylinder?

TIA for any info you might like to offer,

-Scott

Do a better Google search next time.

You need to read some real stuff about pyrolytic graphite manufacturing and then you will understand a lot more.

I am an old fart who was there, and I read paper materials, not web pages.

If you want to actually learn, you may have to go to a library.

I don't do tutorials by typing. Too many illustrations are needed for clarity and it is a waste of time.

You can also look into the pyrolytic carbon heart valves that for many years were at least half of the market for artificial heart valves produced and implanted in the USA.

Your mind has to be able to grasp the geometry of the heart valve and the CVD process. Then you'll see how useful pyrolytic graphite and pyrolytic carbons were.

In pyrolytic carbons, there are certain X-Ray diffraction peaks that can't be resolved but they can be resolved in pyrolytic graphite. The main physical factor involved is the temperature of decomposition with higher temperatures being associated with the graphitic form, as was also true with the bulk electrode business of graphite and carbon electrodes.

Jack Bokros, possibly now dead, was the major player in pyrolytic carbons. "Super" Smith of SuperTemp was a major player in pyrolytic graphites as well as a bunch of technical hotshots at Sandia Laboratories and a bunch more from GE and still many more people who have slipped from my memory.

So, go hit a library for honest research.

Egg sticks to my graphite slab. Conclusion: graphite not good as cooking surface. Pyrolitic graphite would actually be even worse. Grahite oven would probably be fine.

-Scott

Your graphite is typically porous, which may induce sticking by the egg liquid penetrating the pores and then coagulating in-situ.

The bulk specific gravity of the bulk graphite is probably around 1.6 and the non-porous graphite crystal is about 2.25.

Typical porosity, of all pore sizes, for graphite is in the range of

20-40%. Maybe 10% is closed porosity.

Pyrolytic graphite would typically have much lower porosity, only a percent or so based on dennsity measurements, and the physical sticking by pore infiltration would not happen.

You likely should expect pyrolytic graphite to have less sticking, unless you have a specific mechanism in mind that would be stronger with the specific surface of pyrolytic graphite.

However, I never said that pyrolytic graphite would be non-stick.

WIthout oil, stainless steel will stick to an egg. With oil, the egg slides around happy as a clam.

It would be technically correct to say that the pyrolytic experiment should be run..... because you need the data given the number of variables in the materials and the unknown "sticking" mechanism.

Just trying to bring scientific reasoning into an unscientific empirical approach.

Pyrolytic graphite would be a worse skillet surface because of it's poor thermal conductivity on the C plane (worse than alumina). On the A-B plane it's probably much slicker than natural graphite. Sorry that I didn't make that point clear in my last post (--pyro would be worse from a cullinary POV).

I got a definitive answer to my question by experiment (would it be ok to cook an egg on a graphite slab?). The answer is: no, the egg sticks even worse than stainless steel. Experiment cost me $15, including egg. I have other plans for the slab, including some crude glassworking experiments, so it won't be a total waste of money. And besides, it was fun. Tell me you've never experimented on an unknown just for fun or serious investigation. Theory is just one scientiffic tool. Experimental and emperical procedure is the bedrock of all important scientiffic thinking (max plank and blackbody radiation, Einstein and the solar eclipse of 1919, carot and his working fluids investigation, Rutherford and Geiger's experimental supprise discovery of the atomic nucleus, Bridgeman and unsupported packed gasketing... and so on). Man learns new things by doing. I am aware of the problem of reinventing the wheel and so on. Yes it is always a good idea to exhast current literature on a subject before boot strapping an expensive experimental setup.

Usenet is a great place to get and give leads on ideas. Sometimes I simply don't know what to search for. I appreciate your input on the subject, as always.

With enough experimentation an anomaly is bound to contradict theory. All solids contract on freezing: wrong; gallium, water. Liquids don't freeze on heating: wrong; see earlier usenet post. Soilds always expand on heating; wrong, plutonium. Thermal conductivity gets greater at higher temperatures: wrong; most metals. Elecrical conductivity lessens at higher temperatures: wrong; TiC etc. Tensile strenght decreases with higher temperatures: wrong; graphene.

The exceptions to the rule is what makes science facinating and engineering frustrating. Experimentation is very important for both.

Thanks for the chat. I will go to the university library and order up some books on CVD (graphite in particular) when I can get away from this programming gig grounding me to my house. If the library can't find me the info I'll buy the darned books myself. Science literature is not cheap :(

-Scott

That's why there are universities. Your local library can probably get most of what you need if they have participate in the inner library loan system and most do.

Gordon

Programmer, huh?

Keep the day job, the materials science field is not yet ready for you.