An improved clutch or brake device in which at least two members are mounted for relative rotation and engagement, the members having friction material rotatable therewith, and the friction material of the members having surfaces confronting each other, characterized in that the friction material has a solid density of greater than 30% and includes an open lattice of carbon ligaments forming a network of three dimensionally interconnected cells; and a pyrolytic carbon coating on the open lattice of carbon ligaments.