Refractory Materials

I don't think they melt, in the classic sense.

High Alumina Super Duty refractory materials are one of the few materials capable of withstanding temperatures in excess of 3000° F.

thank you, but i mean 3000 degree centigrades.

Yes, I know you do.

That narrows the choices considerably, to diamonds.

Good luck.

thanks

Yes burn all the diamonds!

Even in an oxygen-free environment, diamonds will not withstand even 2000 C (unless at very high pressure). With significant amounts of oxygen, diamonds won't make it above 1000 C.

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Tantalum carbide, hafnium carbide, or tantalum hafnium carbide could be useful.

Are they suitable for furnance refractory materials that can withstand 3000 degree centigrades.

No these materials are not suitable.

Why not just use standard proven furnace-making materials? It's not like your stuck on a desert island and are limited to what you can find on the beach.

Are you sure he's not on a desert island?

"wood, cocoanut shell, cocoanut husk, palm and karnel shell" sounds pretty desert island like to me.

My guess is that OP wants something which has no value to people, so it won't cost anything.

My guess is that OP wants something which has no value to people, so it won't cost anything.

That was my guess too (or they have access to these process waste materials and are trying to use them inventively), although it wouldn't surprise me if he/she was on a desert island, but then why not ask us how to build a boat instead?

The (waste) materials listed would be better suited being burnt as fuel or fuel or low temperature building material additives. Building insulation perhaps?

_{Jack - I've got a lovely bunch of coconuts.....}

So diamonds are out of question now, right.

Or is there a hidden treasure chest?

Not a cheap option that's for sure!

Lyn, maybe he just wants to take these scrap materials that nobody wants and produce hydrogen to save the world!

3000°C. That could do it, with the proper catalyst, of course.

Hey, it's all carbon, right!

Ropo. You asked the following very weird question : "Are they suitable for furnace refractory materials that can withstand 3000C?" and you refer to combustible materials such as wood, coal and so on.

Such a question indicates that you know very little about high temperature furnaces and that you have not researched much nor have you encountered many furnaces (even those of relatively low temperature such as required in the smelting of iron ore - this is around 1500-1600C).

Quite simply put, all of the materials you refer to will burn as they are combustible and many of these are commonly used as combustion feedstock. A refractory material generally is one that will withstand both high temperatures as well as to withstand combustion. There are very few materials that withstand the super-high temperatures you speak about. In the mid-1980's I built such a furnace (induction heating) for lab-scale work. I put in a tremendous amount of research, innovation and experimentation. My desired operating temperature was around 2000C. My furnace was able to reach close to 2300 C if pushed to its limits.

There are very few places in the world that have operating furnaces in the 3000 C range. One clue to all of this is : because the extreme limits of this range of furnace, it invariably has to be a controlled atmosphere furnace. Another clue is that there are are few options for the type of furnaces and the materials of construction. Resistance heating, Induction heating, Arc Furnaces.

As a quick overview of your venture : I would say this is an extremely difficult piece of equipment to design & construct. Your question above shows you have little knowledge of furnaces in general. Let alone furnaces in the range of super high temperatures of 3000C.

This is a seriously high-tech device you are speaking about. I must add that it is extremely dangerous as well. Even the Councils for Science & Industrial Research of most countries do not have such furnaces.

But pray, do tell what on earth would you want to do suth such a beast of a furnace ?

You would be surprised how many incinerators are operational. Waste management of H2S, dangerous mercaptanes, viral and cancerous clinical stuff goes there too.

you have a good question. When the crew of Bounty mutinied and got on the Botany Islands they made a furnace by installing all those materials for refraction. Hoeever, they had a problem ad these materisls would burn rather than melt. Notiving the locals brougjt them Dinisaur bones which when heated with sulphur produved the desired temperature. But even thid did not work for long so much so that the locals brought them tsllow smeared on banana trunks but when the furnace was lighted pearls snd diamonfs came out rolling from the kiln.may sound unbelievable but is said to be true.

To be a little bit fair, I must add that char is also combustible. And yes, there are some refractory materials base on carbon. There are felts or blanket-type materials. They are generally used at much lower temperatures more like 1000C. Now with a bit of lateral thinking I might guess that you mistake Fahrenheit for Centigrade in temperature scales. if you mean 3000 F then there could be a little bit of sense in what you are speaking about. Astronomical difference in the language of furnaces and high temperature. But if true on the assumptions - even this is questionable.

Note : 3000 F is about 1700 C. Last I used them, those carbon-base felts can be used at temperatures around approx. 1000 C, could be a bit more now. But as for char, it would simply burn off. We have used Graphite crucibles (available commercially) in induction furnaces at temperatures as high as 1700C. To get a quick, proper answer always ask the suppliers: Carbon companies such as Le Carbonne (or with the words graphite in their company name) can supply graphite or carbon based materials.

'....the locals brougjt them Dinisaur bones which when heated with sulphur produved the desired temperature. .........the locals brought them tsllow smeared on banana trunks but when the furnace was lighted pearls snd diamonfs came out rolling from the kiln.may sound unbelievable but is said to be true.....'

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Despite the reassurance that this tale 'is said to be true', I am throwing a BS flag on this play.

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I don't think 'dinosaur bones' or what might be left, would make great fuel.

More importantly, the mutiny on the Bounty occurred in the late 1700s. Dinosaur fossils were first recognized as described with the term 'dinosaur' in the early to mid 1800s.

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What kind of construction would a kiln have to have to allow pearls and diamonds to preferentially roll out?

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If temperatures found even in a common camp fire were reached, the diamonds would have burned up.

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What would pearls and diamonds have been doing together inside either banana trunks or dinosaur bones?

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Have you ever encountered a banana trunk? Banana trunks are mostly water and not good fuel.

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I do have to agree strongly with one point in the story provided.....it definitely sounds unbelievable.

there was mis spelling, you correctly wrote dinosaurs, that's it. Have you checked for the chemical composition of dinosaur bones and eggs?? I know banana trunks are used for kick practice by kick boxers.... Check out for The Renovator, it works like a nibbler. It cuts hard materials but is harmless to soft ones...won't even harm fingers. So, unusual things do happen in the world ....and sorry I have no explanation for them...it is..it is said and that's all.

If I were going after your misspellings, there would be many more to note other than your treatment of dinosaurs.

The two biggest problems with the story are the dinosaur anachronism, and the fact that diamonds burn in a fire.

It's okay if one gets the meaning despite typo's. Believe me am not a clerk to be perfect in spellings, moreso when am typing on a miniature virtual screen

Like I said, I didn't call your story BS because of your spelling errors (though I am curious about your excuse of a 'virtual screen').

I called the story BS because it is implausible.

As I stated the story is only said to be true...not true As regards virtual keyboard you will find it on all small touch screen cell {smart) phones ....nothing to be curious about that or is it?

Once you call it a 'keyboard' it is all that curious.

Yes, that's it, a keyboard but a tweeny virtual one on the virtual smart phone screen !! I hope all is clear now:)

Those materials burn before they melt!

PW Slack, This is correct on one level. Graphite or carbon based mats will burn in an Oxygen Environment. However, in a furnace environment which is starved of oxygen the crucible or the mat does not combust to any significant level. This is a reducing atmosphere furnace.

Yes, over time, there will be minor wear & tear as a result of burning on the surface. But it will take many applications or batches of furnace runs for the materials to get damaged. We have used Graphite crucibles in an atomizer furnace. The graphite acts as a Container for impure precious metals (gold or platinum) - up to 60 kg batches. The Graphite also acts as a susceptor in an induction furnace.

All in all, the graphite crucible is a consumable item as it does become damaged but only after around 10 furnace batch runs of approx. 1 hour each. In this application (1800 C), we had no insulation. Nothing between the induction coils & the crucible/ susceptor. In this app there was no need to control the furnace atmosphere.

In a higher temperature application, we put insulation between crucible and coils. We used Zirconia granules as layer 1 and used Fibrefrax as layer 2 between Coils and the Zirconia granules. When you go above 2000C then the effects of oxidation become a serious problem. Even small traces of oxygen entering the furnace will cause tremendous structural damage to the components. Both cases the crucibles was around 20 litres in size. There were limits on how high we could go wrt temperature. Problems are a) Properties & durability of the Insulation materials and b) Efficiency of Insulation. To get high temperature and avoid combustion & wear in the materials of construction you need to introduce inert gas into the furnace.

At the super high temperatures (above 2000C) and at the size we worked at (20 litre crucible), the operation becomes considerably hazardous as one moves higher than 2000C. The energy required is enormous. Only worthwhile if the process material is precious metal. Very expensive to run. Crucibles are consumed after a few batch runs.

You should look at the furnace materials used in fiberglass production as these have the highest melt temperatures in industry that I know of, in order to get the glass flowing as water.

Another concept: just because the furnace is to heat something to 3000 C does not mean the furnace insulation has to suffer this temperature, as you can use clever means to prevent the highest temperatures from reaching the inner sheath of the furnace, albeit this could reduce furnace heat retention efficiency.

Also look at what the proposed materials are for converting ZnO back to Zn metal in solar furnace ( I think the Israelis have mastered this).

Good comment James. Correctly put, the Furnace Insulation does not necessarily have to take a direct beating of 3000 C. However, if it is induction heating, it has to take some temperature pretty close to this figure. This is because the insulation must fit in a narrow layer between the work piece (hot zone) and the induction coils. With resistance heating and arc furnace it is better. But still, these also have limitations as there are few materials with the electrical properties that will stand these temperatures anyway. a) The electrode in arc furnaces. b) The Resistor in resistance heating, for example. In addition, you have to contain the contents of the furnace which will be at the hot zone temperature. So what will the crucible material be ?

I have been through this interesting exercise and still have my notes and contacts books from around1986. Again, I repeat : There are indeed very, very few companies that have achieved this. Reason is that one is approaching the limitations of materials properties and the limits of furnace knowledge. Often the companies that do have this know how will not reveal their techniques. I will give you a clue and then stop with advice from here on.

I know of only 3 or 4 possible materials that are suitable from an electrical and a thermal point of view (in high temperature furnace technology). Apart from this, one may want to look at plasmas which a different technique altogether.

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agreed.

thank you i really appreciate your contributions

http://www.mrf-furnaces.com/listhitemp.htm

This company lists graphite or tungsten lined furnaces to approach 3000 C. I presume a reducing atmosphere, although the link mentions one with oxidizing atmosphere.

Graphite furnace is used in atomic absorbption spectroscopy to determine quantitatively the presence of certain elements at low levels.

I do not think plant derived materials such as charcoal are sufficiently graphitized to survive such an environment as you specified, but with good luck you could perhaps convert enough of the material when exposed to 3000+ C. Perhaps if you repeatedly heat this material in inert gas (not specified) you could end up with something apparently like graphite that could be pressed into shape (if you need shape). Another method is a charcoal material formed into electrode in inert gas and produce an electric arc between the electrodes. (Usually arc furnaces are used for iron recovery from ore, and these use graphite electrodes). This should produce relatively pure graphite as vapor, which will solidify all over any cold surface. Also, heating silicon carbide to wickedly extreme temperatures will vaporize the silicon away, leaving behing pure graphite.

Great find James. This is what I found in 1985 whilst playing around with high-temperature furnaces. I looked at Graphite first and then switched to Tungsten. I manufactured the Tungsten component myself. [very few companies in the world can do this - even today]. Metaalwerk Plaansee in Austria is one of them. The one you brought to our attention also. I am now following up the company you listed.

Note, I was stuck with Induction Heating at the time. The Graphite could possibly work with Resistance Heating. In my efforts with Induction heating, I dropped Graphite and used Tungsten which succeeded. By the way, this was one of my better projects ito innovation. I have re-documented this project as a case study. The furnace had a mass balance to constantly weigh the crucible contents. This is the so-called thermo-balance. It is very difficult & quite tricky to build this kind of equipment. Thanks again for finding this website for us. It looks like it may contain ideas and technical know-how that I was not able to thionk of way back in 1985. Incidentally, I was unemployed at the time and found an abandoned project at a University in SA. I was able to get an MS Chem. Eng out of this project.

I will follow up with you as I go through the said website.

whenever I can be of general service to the community of scientists/engineers I find great happiness in that.