Self-healing diamond/geopolymer composites fabricated by extrusion-based additive manufacturing

Abstract

Geopolymers are easily molded and mixed with various additives to form composite materials with desired functions. In this study, the gradient diamond/geopolymer composites (DGP) are fabricated based on the extrusion-based AM technique. Diamond disturbs the chain structure of the geopolymers, making the slurry easier to extrude with delayed solidification time and reaction rate. The interfacial characterization shows that a larger volume secondary mullite are formed from mullite phase under the condition of sufficient thermal transform from the diamond, thus achieving the self-healing process of pores and cracks at room temperature. The results of heat treatment of the DGP prove that the diamond effectively optimizes the thermal stability with fewer pores and cracks. Self-healing of damage in engineering materials can be achieved by reducing the crack widths during service process, which highly extends the life cycle and saves the operating cost. 3D printed geopolymer/diamond composites are successfully fabricated with self-healing ability and thermal stability. • Diamond/geopolymer (DGP) composites fabricated by extrusion-based additive manufacturing. • The DGP has a role in effectively delaying solidification time and increasing printing efficiency. • The DGP enables self-healing process of pores and cracks at room temperature. • The DGP could effectively enhance the stability of the sintered parts at 1200 °C.