Titanium Rotor

[kiwi_mtm]

Airplanes often use Beryllium rotors which conduct almost as well as aluminum but are LIGHTER than aluminum and much much stronger. They also don't melt as easily. And suprisingly, copper conducts heat almost TWICE as well as Aluminum does, is harder to melt than aluminum, stronger, and only weighs just slightly more than the stock Iron. If you compare it to Iron it transfers five times more heat and only weighs about 10% more! Anyone try a copper rotor? [img]images/graemlins/laugh.gif[/img]

Cheers,
Adrian W

And just imagine how cool and unique they would look!

[wazza]

Airplanes often use Beryllium rotors which conduct almost as well as aluminum but are LIGHTER than aluminum and much much stronger. They also don't melt as easily. And suprisingly, copper conducts heat almost TWICE as well as Aluminum does, is harder to melt than aluminum, stronger, and only weighs just slightly more than the stock Iron. If you compare it to Iron it transfers five times more heat and only weighs about 10% more! Anyone try a copper rotor? [img]images/graemlins/laugh.gif[/img]

Cheers,
Adrian W

And just imagine how cool and unique they would look!

Then imagine all the pikeys robbing your car and taking it down the scrappy [img]images/graemlins/biggrin2.gif[/img]

[SaabTuner]

Indeed, but that's true of any nice pair of brakes. While for racing purposes copper isn't as good as Beryllium or Carbon, for a street car it could be very adequate. Trouble is that it oxidizes much like iron does, and this oxide is greenish, which might look a little weird. But I thought of a solution. They make heat dispersal coatings that help the transfer of heat. These same coatings should also prevent excessive oxidation. Whereas some of the electroplating that is currently done to rotors often makes heat transfer WORSE. Anyway ... just more to think about. Cheers everyone. [img]images/graemlins/smile.gif[/img]

Adrian W

[Carps]

Wouldn't copper be too soft ?

[SaabTuner]

It's hard to say. Since even "cast Iron" is actually an Iron Carbon alloy much like steel it won't have the exact same properties as pure iron. But it shouldn't be too drastically different, so if we compare Iron (Fe, crystalline structure: Cubic, body centered) and Copper (Cu, crystalline structure: Cubic face centered) ... (I also added carbon [C, crystalline structure: Hexagonal] to give you some idea how soft carbon racing brakes would be compared to copper and Iron) ...

Coefficient of Linear Thermal expansion
Cu: 0.0000166cm/cm/°C (0°C)
Fe: 0.0000118cm/cm/°C (0°C)
C: 0.0000021cm/cm/°C (0°C)


Thermal Conductivity
Cu: 4.01 W/cmK
Fe: 0.802 W/cmK
C: 1.29 W/cmK

Density
Cu: 8.96g/cc @ 300K
Fe: 7.874g/cc @ 300K
C: 2.26g/cc @ 300K

Elastic Modulus

Cu:
Bulk: 140/GPa
Rigidity: 48/GPa
Youngs: 130/GPa

Fe:
Bulk: 170/GPa
Rigidity: 82/GPa
Youngs: 211/GPa

C:
Bulk: 33/GPa

Hardness

Cu:
Brinell: 874 MN m-2
Mohs: 3
Vickers: 369 MN m-2

Fe:
Brinell: 490 MN m-2
Mohs: 4
Vickers: 608 MN m-2

C:
Mohs: 0.5

Melting Point
Cu: 1085°C 1984°F
Fe: 1535°C 2795°F
C: 3500°C 6332°F

While copper might be just slightly softer than iron it conducts 5 times more heat than Iron and about 3.1 times more than Carbon. As for strength they should be nearly equal. Copper does melt sooner, but since it conducts 5 times more heat it should be considerably harder to get it that hot on a street car. Probably not the best racing brake rotor material, but even race brake pads stop working well before copper melts, and you can usually see little bits of copper in your pad material as it's been used in pads for years. I'm not saying we should all go out and buy copper rotors (if anything trying Beryllium might be interesting), but it could be worth a try if it hasn't been done already. After all they do use it in head-gaskets, exhaust gaskets and lots of other high heat applications where thermal conductivity is important, why not brakes? [img]images/graemlins/smile.gif[/img]

Cheers,
Adrian W