i have been told that silicon carbide is even more harder that diamond. Is it true. if yes then how?

how much does it cost to manufacture silicon carbide disc brakes

does anyone know?

dear sir , we are an automobile manufacturing unit . we need alumina fiber ,silicon carbide fiber, and other avilable metal fiber for our new automobile fabrication .please give details about above materials , otherwise give sugesstion where we can able to get above mentioned materials