... uh... grain structure unity? Doesn't work that way... smaller grain boundaries that aren't aligned with each other lead to tougher materials because any crack that occurs doesn't have a nice clear path to keep growing. The little silicon carbide particles help break things up a bit more too.

Besides which, silica and silicon carbide are two very very different things.

And titanium... I'd love to hear how you'd plan to forge a rotor. Or why titanium, aside from that it's Das Generic Ubermetal. I mean, why not just AlBeMet?

 

Even though this dead horse has been beat enough, I feel the need to reply. Titanium is an awsome material. I am also a machinist and have dealt with many different materials. Ever machine Inconel? The problem lies in the fact there is no ubermatal. They all, for their noted upsides, also have downsides.

As mentioned earlier, Ti has crappy wear resistance. If all you were going to do was to take equal dia. bars and beat them with a sledge hammer, Ti wins!

Another draw back is oxidation while molten. If not shielded, to the point of burning. In other words it cannot be cast outside of almost lab-like conditions.

I must add that I believe an aluminium rotor is possible useing some sort of insert, either cast in place or added later, for the apex seal groove. Wether it is worth the trouble or not, I don't know.

Edit for clarity: Take eqaul dia. bars of different materials and beat them with a sledge hammer. Ti wins!

 

Err,.. silicon carbide reinforced aluminum (MMC) is what they are using in F1 cars for pistons after they banned albemet,.. i'm pretty sure it works just fine actually,..

 

Er... bars of equal diameter? Ti wins against a lot of non-ferrous alloys, but heat treated 4140, or 4340, or 5160, or 8620 steel... (to name just a few) beat it. Sorry.

 

So Tony are you saying that aluminum could be CNC to fit this application with steel inserts for the apex seals? what about the expansion differentials of the two metals in direct contact with each other? What type of treatments and coatings would be required? Like Keronite?

How about a soft seal with minimal life expectancy rather than making inserts for the seals?
I mean obviously this would be an expensive venture if one was purchasing these it would be for race app. only so with that said using soft seals that would need to be replaced after a few runs or few races wouldnt be that bad and correct me if I am wrong here but a softer seal will seal better?

 

My point was that if someone really wanted to do this,with no care to cost, I believe it could be done. I'm no engineer. But it is just an engineering problem.

I think you could cast a rotor, just like they are cast now, out of aluminium, with considerations for added wall thickness, just as they are made now, finning for heat transfer,and coatings where needed. And at considerable expence.

But will it hold up? Who's got a pile of money?

I also agree that the added weight of necessary beefing would not end up in a half weight rotor. After all, the first pistons that were made were not made of aluminium.

 

[QUOTE=tinvestor]So Tony are you saying that aluminum could be CNC to fit this application with steel inserts for the apex seals? what about the expansion differentials of the two metals in direct contact with each other?



Cast iron sleeved aluminium blocks.

 

The cast MMC is actually a really good idea, probably the best idea of this thread. It would have nearly identical strength/stiffness/wear resistance of the stock cast iron rotors at about 1/3rd the weight.

 

random bump

"Such efforts are in the initial stages of development, exemplified by a program to replace the metallic rotor in a rotary (Wankel) engine, with a silicon nitride rotor."

department of defense is also interested in other types of rotors for UAV's

 

[quote=tinvestor]So Tony are you saying that aluminum could be CNC to fit this application with steel inserts for the apex seals? what about the expansion differentials of the two metals in direct contact with each other?

That is what Mazda did for the MX-03 3 rotor prototype car in the '90s as well, aluminum rotors with ceramic combustion recesses, steel inserts for the ceramic apex seals to ride in and side seals just in the aluminum of the rotor.

 

Aluminium can be harmful near brakes due to gas which aluminium releases when it get heat.It should effect the brakes that will be too dangerous.

 

^ not only is this a 7 year old thread, they were talking about engine rotors, not brakes. good job.

 

Aluminum brake rotors.....Lol...good one.