Polymer for Turbine Blade

I suggest you start by discussing the application with DuPont Product Application techs. About 20 years ago, AMOCO (now part of BP, fabricated ,assembled, and ran a 4 cylinder gasoline engine made almost completely from 'plastics'. I do not know if your needs can be met, but the DuPont folks would know what might work

DuPont is a pain. Remember they are the company that told us "Without chemicals, life itself would be impossilble" and brought us such things as DDT and Agent Orange. You emay want to incorporate a braided substrate and then mold a thermoplastic or thermoset polymer over it. A braid can provide a very good reinforcement for a low cost and improve the overall performance of the product. we have been able to increase the pressure resistance of a vessel from 5Kpsi to 18Kpsi with a correctly designed braid. braid can be formed to almost any shape with the correct tooling. Do not be fooled that a braid 'sock' will work. the braid needs to be form onto the part or a mold of the part.

Scarecrow from the Wizard of Oz. I am NOT smart enough to know that I can't do it!

I would suggest that you consider Teflon- It is highly stable, virtually non-reactive, can be thermo-molded into nearly any shape that you can design and it maintains its shape up to temperatures of over 700F.

I will send you a private message with a company that does these fabrications.

Teflon – PTFE, is not all that a stable material unless filled with Carbon or glass. High temperatures, yes, but might get de-shaped on dynamic action. Injection molding may not be possible but can be molded by special process like sintering. Pressed shapes would get back to original shape on heating, since they remember the original shapes.

Why polymer in the first place. Well, OP may have reasons not to reveal. How about fiberglass-lined steel?

The sintering process you mentioned uses very fine particles of teflon that are hydro-formed into the required shape then heated to gel state for 8-12 hours where they become a single chunk of teflon.

Yes, for even higher total strength, the preformed shape could be enhanced with carbon or glass fibers or mesh, but the real value of teflon- aside from its high temp capacity- is what you alluded to. It forms a shape with incredibly long chemical bonds that wants to remain in its shape (the memory you mentioned) even with pressure applied.

PTFE (Teflon) used to have a high end temperature of around 450 degrees F. It cold flows and is porous to smaller molecules. Use with caution.

PTFE is physically stable up to about 625F, turns to gel at about 650F and sintered at abut 700F. Even as a gel, its long chemical chain prevents it from "slumping" on vertical surfaces even after it is heated to gel state.

It is use extensively in the chemical industry (especially for materials like strainers) and for coatings of pump impellers (including pumps that handle slurries) and valve faces and bores.

PTFE changes shape while sitting quietly on a wharhouse shelf if left there for long enough.

I can give all of you my short list thus far. I have not examined all their characteristics thus far and some may be eliminated. I would appreciate any comments you many have on these products: FKM, PAI, Polyaramid, PBI, PI, PPS 40% GFR, PTFE, and Torlon 4275. I am open to other products if you have suggestions. Did I mention that it should have a high fatigue tolerance?

I would look at carbon fiber/epoxy layup. PTFE will cold flow at room temp and pressure, just sitting on your desk it will eventually sag from it's own weight, put it a high temp rotating environment like you describe and it will come apart in minutes. Glass fiber filling it won't help much. That is why it is no longer used by itself as an aircraft wire insulation, the conductor will eventually drift down to the point that it is in contact with the surface the wire is laying on. especuially if the surface is an edge which acts as a stress concentrator.

This is in fact true of most all polymers to one degree or another and the hotter they are or the more stress they are under the more it will happen.

Consider a ceramic like Transformation Toughened Zirconia for this application. It is extremely strong and fracture tolerant. It is designed with microscopic crack stopping grains that improve it's fracture toughness by a frighteningly high degree. St. Gobain had a sledgehammer with TTZ faces on it at a trade show I read about in which they invited visitors to hammer on an anvil with the TTZ sledgehammer and offered a huge prize for anyone who was able to break the hammer face. Nobody won the prize.

TTZ is also VERY hard (only cubic zirconia and diamond are harder) so erosion should not be an issue at all. It DOES have corrosion issues with high temp water and Amines, but this should not be an issue with the flourocarbon working fluid you mentioned in your previous post.

"My working fluid has a vaporization temp of around 220 c" This is not exactly less than water! Or is it 220°F you meant? Also not exactly less than water.

What drives your requirement for a polymeric material?

Bear in mind that although your working fluid may not be corrosive to metal it does not mean that it will not damage polymeric material. Remember corrosion can take on many form from gross surface attack to more subtle forms such as stress corrosion cracking. It all depends on the specific combination of working fluid and material. Polymers may also be prone to creep at sustained loading, especially at elevated temperatures. Elevated temperatures for polymers dont have to very "hot".

If you are considering polymers specifically so as to be able to use injection moulding you could consider die casting or metal injection moulding. Alternatively you could consider investment casting.

Without details of the working fluid, operating conditions and approximate design it is impossible to recommend any specific materials.

Stupid question, but why must it be a polymer again? why not cast/sintered pot metal? or brass/bronze? or aluminum?

BTW, FKM, FFKM, and PTFE are unsuitable for use with a flourocarbon based working fluid as they will swell and deteriorate quickly. (corrosion is not just for metals you know.)

When I said that my working fluid had a working temp of 220c and that was less than water; I was speaking of superheated steam. I should be more careful when I state specs, my apologies. I spoke with Dupont and have specs being sent to me on the 3 Teflon products; PFA, FEP and PTFE. PTFE is the least desirable because it does not fit the injection mold requirement. According to the engineer I spoke with, PFA, although 3 times the price of PTFE, it can be injection molded and that saves processing time and equipment. My reasons for using a polymer are many fold and I will see if it is possible. My reasons will become clear as I progress with this project. The next two years will try my patience I am sure. That is the time I have given myself to prove this project.

Probably overkill and too expensive, but polyimides have excellent high temperature and mechanical properties.

I've never used them myself so have no direct experience here.

I have researched the polyimides and have narrowed my searching to Torlon, Peek or Telflon. All of these have compounds that "fit the bill". All of the costs are similiar(very high) but the enhanced characteristics will make for a leaner product and hopefully offset the increased cost of the polymer.

you can forget Teflon. It isn't compatible with the HFC working fluid and cannot withstand the centrifugal forces involved. Not to mention the fact that regular teflon can't be injection molded. (PFA can but the other issues still apply.)

TIVAR

Tivar is a nice product but cannot tolerate the temperatures I will be subjecting it to. My working temperature is in the range of 200c. Tivar's range is 200f.