The properties and behavior of carbon fiber reinforced silicon carbide composite brake pads on a steel brake disk during a dynamometer test for frictional applicationsMittwoch (05.07.2017) 13:20 - 13:40 Uhr Bestandteil von:
Ceramic matrix composites like C/C-SiC combine the high strength, thermal stability, wear resistant, and low density of ceramics with an additional damage tolerance due to the carbon fiber reinforcement. Hence, these materials can be used as lightweight high performance frictional material especially for emergency and service brakes forced to withstand very high power intensities. In this study the frictional behavior of fabric reinforced C/C-SiC brake pads with a frictional surface of 400 mm2 paired with a steel brake disk of 380 mm diameter were investigated with respect to the influence of brake pad pressure and the composition of the ceramic brake pads. Particular attention was given to the wear, the coefficient of friction (COF), the temperature development within the frictional couple, and the peculiarity of the COF progression curves. The dynamometer tests were performed with a flywheel of 100 kg*m2 rotational inertia and a starting sliding velocity of up to 20 m/s. This leads to initial power intensities up to 800 W/mm2 and a work of friction of about 0.6 MJ for each test run. The temperature was measured in situ close to the frictional couple with a fast responding miniature thermocouple and achieved up to 700 °C. Increasing the pad pressure from 20 to 40 MPa decreases the COF by up to 30 %. The progression curves of the COF can show an initial rise and falling of the COF value at the beginning of braking and an inherent arise of the COF value at the end of braking. To evaluate the reasons of this COF changes, the surfaces of the brake pads were investigated with regard to roughness and surface composition.