Expert: Ray Wilkinson - 8/16/2006

Question
i  am doing my project about the aircraft brake with respect to the different temperature.i would like to know the carbon fiber ratio in the matrix. and also what will happen in the microstructure of the carbon brake at -30- 40 degree celcious?Can you please help ?it will be very useful to my project.
Thank you
yours truly
jansy sharmili

Answer
Hi Jansy

Sorry, I don't know a great deal about carbon brakes, but I'm certain there will not be any resin in them as it would not resist the temperatures the brakes reach. I'm fiarly sure that it's 100% carbon, but I don't know what technique is used to bind the material together - my guess would be sintering. Carbon brakes operate at much higher temperatures than previous materials, over 1000 degrees C, which is why they can be made lighter than metal-disc brakes. There is no problem with very low temperatures either, again because there's no resin. As you probably already know, all civil aircraft brakes are likley to reach these low temeratures anyway, as they will start off fairly cool (they aren't used much during taxying), and the air temperature will be around that point for most of the flight.

I hope this helps.

Regards, Ray.