I think the best option is Humo Seco, I don´t know the name in english.
well, i should to specify more but you would say that you should looking for in the polyamide
http://en.wikipedia.org/wiki/Polyamide
But, do you whant mechanical propierties, or electrical....?
It is not clear what temperature you want to withstand to keep the mechanical properties.
but in automotive industry usually use Polycarbonate,Poly-amide 6 and 66 and SMC.
The high (800-1100 deg C) operating temperature, precludes the use of a pure polymer. All polymers are predominantly organic in nature decompose around 350 - 700 deg C and hence are never used for their thermal properties.Thermoset materials like Phenol Formaldehyde (Bakelite) have high temperature resistance, they are used as ablatives in exhaust nozzles of rockets, because when they degrade at high temperatures they form a residue having excellent heat insulating properties, hence preventing heat conduction into the other parts of the rocket/shuttle(hence they are not used purely for their thermal properties). I presume yours is a space application for which composites like Ceramic matrix composites (CMC), Metal matrix composites( MMC) , GLARE (relatively new composite, very low density though operating temperature around 600 deg C or so (I am not sure about the operating temperature, hence please look it up) are used.
A clarification-your application seems to be in the area of automobiles (just visited your website) - for such apps MMC are predominantly used ( as CMC's are brittle in nature )
Mr. Vinoj, the project is not based on automobile. It is to fabricate an rotational viscometer an find the viscosity of materials at constant temperature (in semi solid state- thixotropic behavior) but by varying the shear rate. For designing the bob of the viscometer, i want a materials which has low density and high melting point. using GLARE or other composites is not much economical for the purpose of bob alone.
Melting point of a material is dependent on the density (i.e they are directly proportional ). The melting point of a material is a measure of the cohesive forces holding the molecules together which in turn depends upon the density of the material viz higher density - higher melting point ...
The upper limit of operating range(1100 deg C) rules out the use of any "polymeric material"
Traditional viscometers ( atleast those I have worked with ) have their bob/cone/plate made of metals.So for your temperatures you need to go in for Titanium alloys ( high temperature resistance and is also light ) and will also be expensive.
You cannot have the best of all worlds.....density, melting point and cost...!
If are polymeric film, the best are polyimides.
If an aqueous solution is the best polivinilalacohol-co-vinyl acetate.
Mr. ram no Polymer can withstand till 1100 deg. i have done lot of thermogravimetric analysis of various type of polymer and found that normally all polymer degrade at 800 deg. you know even platinum has a vapour density at 1200 deg Celsius. Vinoj vasu suggest u a good option. we are also using viscometer that works for rubber, that are also having metal plates. anyway u can try EPDM rubber with some heat resistance filler and sulfur curing system. that will be having low density around 1.4 max but temp. resistance will be i think max 600 deg.
Reply is it an useful information.
dear friend I can help you in shaa ALLAH please what is temperature range do you need and what is all stresses or what is your application you can contact me directly [email protected]
Hi
My major is Metallurgy and i dont have any idea about polymers ! but i know copper & beryllium alloy (C17000) that use it in nuclear reactor and high temperature with low strain !
the best polymeric material for bearing a temperature was 450 deg celcius - teflon (poly tetrafluro ethelyne ).and you can try the blend of teflon and some other TPE such as urethanes to achive 700-800 deg celcius.
I think you should go for some polymer composite. If want some more i can tell you.
Dear Ram,
Is the density so critical?. If not, you can use metals ( the most stable and preferred for high temperature measurements). When you choose a material for you bob, it should be stable both chemically and mechanically at high temperatures. Preferred metals are Pt-Rh alloys, Pt, Mo, Ni, and Fe. When using these metals you should take care that inert atmosphere prevails in your system ( Especially Fe since it oxidizes). Regarding the crucible material you could used the same. Also ensure that the bob is completely immersed in the molten bath. For high temperatures you can use Mo wire to hang your bob.
You can have high thermal resistance by using any suggested polymers above and low density only possible with the exploitation of structure, more amorphous. I have seen one product from Japan, highly thermal resistance but they made its structure porous,
I think for your temperature range only a technical ceramic would work. Then you have low density combined with a high application temperature. Have a look at the typical typs like Al2O3, SiC, Si3N4, MgO, ... there is a wide range to choose from.
Ram... You have not mentioned what liquid are you studying .. Its only then you would get the best answer for the crucible and bob material.
Mr. Vasu is correct - a low cost solution may not exist and all primary options have been listed. One (fringe) possibility could be a cast, cellularized Geopolymer, for both low mass and cost. Fully reacted geopolymers are stable up to 1000 C and may be formulated to exceed 1100 C. They are very low cost, relatively easy to work with and cast beautifully with inexpensive acrylic tooling. Toughness can be improved with short basalt fiber reinforcement which is also stable to 1000 C if not 1100. Various cellurizing agents are available - check AAC (Autoclaved Aerated Concrete) literature.
I regularly use Vespel at 310C to 290C for calibration of thermal conductivity apparatus. I have also come across composite materials whose Tg is around 400C, but above that I think you need to look at ceramics or metals as others have suggested. john gearing UK
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