Damping properties of consolidated iron and graphite powders

Upon increasing the strain amplitude, the damping capacity of sintered (800°C, 1 h) pure iron powders changes slowly at low strain amplitudes, increases at a threshold strain amplitude of about 8 × 10−5, reaches a maximum, and then decreases. This behavior is the same for sintered graphite powders as well as for mixtures of graphite and iron powders except that the threshold strain amplitude is lower (2 × 10−5) for the composite. However, the low threshold is similar to that of the cast iron. With increasing graphite content, the modulus of the composite decreases, but the damping capacity increases. Both the damping capacity and Young's modulus of the composite are comparable to those of cast iron.