Recycling boron carbide dust waste for preparing high-performance ceramics by hot-pressed sintering

Abstract

B₄C dust waste causes environmental pollution and is difficult to be recycled. This paper proposes a method of recycling B₄C dust waste to fabricate high-performance ceramics via the processes of raw material treatment and hot pressing. The characteristics of B₄C dust waste are analyzed and the existing states of the impurities are detected. Dust wastes, removed different impurities via different processes, are simultaneously hot pressed at 2050°C for 15 min under 20 MPa pressure, and the microstructure and mechanical property of the fabricated ceramics are detected and compared. Results indicate that the particle size of dust waste is fine (2.7 µm), and the impurities B₂O₃/H₃BO₃, Fe, and BN exist in dust waste. The mechanical properties of the ceramics fabricated with dust wastes treated via different methods are similar or even superior to those of the commercial ceramics, and among them, the ceramics fabricated with the dust waste removed oxygen with ethanol show the excellent comprehensive performance, of which the hardness, flexural strength, and fractural toughness reach 30.78 GPa, 410 MPa, 4.3 MPa m^1/2, respectively. Removing oxygen of dust waste can effectively enhance the densification, and the impurity Fe can also improve the densification owing to the formed low-melting-point FeB from the reaction between Fe and boron carbide in the dust waste. The pullout of FeB, BN particles, and the loosening area induced by residual stress of FeB contributes to the promotion of fracture toughness. This paper proves the feasibility of preparing high-performance ceramics with B₄C dust waste and lays a theoretical and practical foundation for the recycling and value-added reuse of B₄C dust waste, and for the low-cost preparing of high-performance B₄C ceramics.