Bulk Amorphous Carbon with Lightweight, High Strength, and Electrical Conductivity: Onion-Like Carbon Structures Embedded in Disordered Graphene Networks

Amorphous carbon exhibits superior performance over its crystalline counterparts due to its unique structural configuration characterized by short-to-medium-range ordered and long-range disordered structure, which fundamentally expands its potential applications in advanced technological fields. The exploration and preparation of novel bulk amorphous carbon materials through innovative synthesis approaches remain crucial in materials research. Here, we successfully synthesized bulk amorphous carbons composed of onion-like carbon structures embedded in disordered graphene networks prepared via spark plasma sintering of carbon black at a pressure of 50 MPa and temperatures ranging from 1700 to 2200 °C. The bulk amorphous carbon demonstrates a unique combination of low density and exceptional mechanical and electrical properties. The sample synthesized at 2200 °C exhibits superior mechanical properties with nanoindentation hardness of 603 MPa, Young's modulus of 6.78 GPa, compressive strength of 169 MPa, and flexural strength of 69 MPa, comparable to the commercial ISO-68 graphite from Toyo Tanso Co., Ltd. In addition, this bulk amorphous carbon exhibits excellent electrical conductivity, reaching 9.3 × 10³ S/m at room temperature. This type of bulk amorphous carbon demonstrates particular promise for advanced applications in aerospace engineering, energy storage, electronic devices, and precision machinery manufacturing.