Abstract: A friction-clutch system having a friction disk unit including a central hub and friction disks, wherein the friction disks have friction surfaces. At least one friction surface of the first to fourth friction surfaces is constituted of a combination of a carbon/graphite material and a metal/ceramics material, wherein the carbon/graphite material forms a friction surface made from a carbon/graphite material, and a metal/ceramics material forms a friction surface made from a metal/ceramics material, wherein the ratio of [the area of the friction surface made from the metal/ceramics material]/[the area of the friction surface made from the metal/ceramics material+the area of the friction surface made from the carbon/graphite material] ranges from 0.05˜0.65, and wherein pressure between the first and the third friction surface and between the second and the fourth friction surface is 10˜250 N/cm2 while the power is being transmitted.