Nickel Fiber Silicone-Matrix Composites as Resilient Electrical Conductors

Short nickel fiber silicone-matrix composites containing 3–12 vol. percent fibers were fabricated by the impregnation of silicone into a nickel fiber perform. The composites exhibited volume electrical resistivity ranging from 4.5 × 10⁻⁴ to 2.8 × 10⁻³ ohm.cm, contact electrical resistivity (with copper at a pressure > 0.1 MPa) ranging from 0.0090 to 0.0155 ohm.cm², permanent set one percent after compression to a stress of 0.4 MPa and a strain up to 13.5 percent for 7 days, and electromagnetic interference (EMI) shielding effectiveness > 50 dB at 1.0–2.0 GHz. The volume and contact resistivities were essentially not affected after heating in air at 130–150°C for 7 days. The coefficient of thermal expansion was 27.5 × 10⁻⁶ °C⁻¹ for a composite containing 8.2 vol. percent nickel fibers. These resilient electrically conducting composites are useful for electrical contacts and for gaskets for EMI shielding.