ZrB ₂–SiC spiral fibers prepared by combining liquid rope effect with non-solvent-induced phase separation method: A promising toughening material for ultra-high temperature ceramics

Spiral fibers were considered to be an ideal toughening phase of ultra-high torsional release effect. In this work, ZrB2 (Z)–20 vol% SiC (S) spiral fiber (ZSsf) with controllable structure was prepared by a combination approach liquid rope effect and non-solvent-induced separation. Dominantly depended on the kinematic viscosity (η), dropping height (H), flow rate (Q), geometric parameters ZSsf involving filament diameter (d) coil (D) followed relationship d ≈ 0.516×10−3Q1/2H−1/4 D 0.25×10–3(Q/H)1/3, respectively, within optimized η 10–15 Pa·s. Three different microstructures achieved adjusting polymer/solvent/non-solvent system assisted diagram calculation, including dense, hollow, hierarchical pore structures. The ZrB2–SiC 1 wt% composites hot isostatic pressing (HIP) exhibited ~30% increase in fracture toughness (KIC, 4.41 MPa·m1/2) compared composite, where microscopic ~80% higher than that matrix. ~10 nm in-situ-synthesized graphite amongst grain boundaries changed mode, promoted crack deflection pull-out adjacent interface matrix fiber.