This article reports the first example of 3D printed continuous SiO₂ fiber reinforced wave-transparent ceramic composites via an adaptation of direct ink writing technology to improve the mechanical and dielectric properties of ceramics. The ceramic inks showed good printability by adding nano-SiO₂ powder. The effective continuous fiber-reinforced printing progress was achieved through the design and optimization of the coaxial needle structures by finite element simulation. After printing, the continuous fibers were evenly and continuously distributed in the matrix ceramics and the high molding precision for fiber reinforced composite was kept. It is demonstrated that 10 vol% continuous SiO₂ fiber improved the bending strength of ceramics by about 27% better than that of the ceramics without fiber and the dielectric performance has also been greatly improved. The novel method unravels the potential of direct ink writing of continuous fiber reinforced wave-transparent ceramics with complex structures and improved properties.

Here, we demonstrated a novel synthesis of a polyborosilazane (PBSN) precursor using hydroboration and aminolysis reaction synergies to modify polysilazane (PSN). Specifically, borane·tetrahydrofuran and boron trichloride·hexane were used as dual boron sources, which not only reacted with Si–Vi and Si–N–H functionality respectively to modify multiple active sites of PSN resulting in boron-rich silicon–boron–carbide–nitride (SiBCN) ceramics, but also improved controllability on composition, molecular structure, as well as final features. The resulting structures were characterized by FTIR, solid-state ¹¹B and ²⁹Si magic-angle-spinning NMR and inductively coupled plasma emission spectral (ICP) analysis. These polymers were found to be structurally complex networks composed of tri-coordinate BC_xN_3−x and tetra-coordinate BC_xN_4−x bridges. The resulting polyborosilazanes contained ∼11 wt% higher boron contents than that in the starting polymer. The structural evolution of the resulting polymers was evaluated by means of XPS, FTIR and XRD, and TGA-DSC-QMS was utilized to detail the precursor-to-ceramic conversion.