Upcycling of waste diamond wire sawing silicon powders to prepare Al-50Si composite by hot-pressing sintering

The disposal of waste diamond wire sawing silicon powders (DWSSP) generated during solar-grade silicon wafer production is crucial for the sustainable development of the photovoltaic industry. To achieve the resourceful utilization of DWSSP, a method to prepare Al-50Si composite by upcycling DWSSP through hot-pressing sintering (HPS) was proposed. The effects of hot-pressing sintering temperature, pressure, and current on the densification of DWSSP and Al powders were investigated by finite element modeling analysis and experiments validation. The numerical simulation results showed that pressure-assisted sintering triggered the percolation effect of interparticle currents coupled with localized high Joule heat, accelerating the interfacial reaction between DWSSP and Al powders. It was found that the Vickers hardness and density of the prepared Al-50Si composite increased and then decreased at sintering temperatures of 450-500 degrees C and showed a positive correlation at pressures of 50-200 MPa. Optimal conditions of 475 degrees C sintering temperature, 150 MPa sintering pressure, and 5 min holding time yielded Al-50Si composite with a density of 2.36 g/cm3 and a Vickers hardness of 201 HV0.1. The findings demonstrate the application of HPS method allows for the grave-to-cradle waste management of DWSSP and the preparation of recycled Al-50Si composite for its high value-added utilization.