Facile preparation of heat-conducting ceramics/epoxy composites by pre-constructing Si3N4–SiC skeleton from photovoltaic silicon waste

As a by-product of solar panel production, photovoltaic silicon waste (PSW) is becoming a threat to the environment and human health. The classical resource recycling approaches are separating Si and SiC from PSW, most of which is costly and inefficient. In this study, the PSW acted as a silicon source was directly translated into a vertically oriented 3D Si3N4–SiC skeleton with ice-templating and in situ nitriding technology. The Si3N4–SiC/epoxy (EP) composites were successfully produced by the following vacuum epoxy infusion. Composite with 55.46 wt% filler content had the maximum thermal conductivity (TC) of 1.717 W/(m·K), 950 % higher than pure epoxy. The composite substrates showed excellent heat dissipation performance in practical applications due to their high TC, primarily attributed to the directional arrangement of ceramic powders in the Si3N4–SiC skeleton. Additionally, the Si3N4 whiskers produced in situ promoted the formation of wider continuous phonon heat transfer channels. In short, we proposed a simple and feasible approach for recycling PSW to fabricate high-value heat-conducting composites, which expands a new direction of industrial waste secondary recycling and is of great importance for the clean utilization of the resource.