Ceramic fibers have played an important role in the thermal protection field of aerospace vehicles at high-temperature over the past decades. In this work, Y 2 Si 2 O 7 precursor fibers were prepared by electrospinning and characterized. The spinning solution consisted of yttrium nitrate, tetraethyl orthosilicate , and polyvinyl alcohol. The microstructure and elements distribution of fibers was investigated by scanning electron microscopy. The decomposition of organic components and crystallization process of yttrium silicate were explored by thermogravimetry-differential scanning calorimetry. The phase composition of fibers was analyzed by X-ray diffraction. The results showed the fibers were composed of uniform tiny grains after calcined at 1000 °C and the phase of the fibers was α-Y 2 Si 2 O 7 . The size of grains increased with increasing calcination temperature and the intact fibrous structure was maintained. The average diameter of the precursor fibers was 1383 ± 345 nm and decreased to 786 ± 171 nm after calcined at 1300 ℃. Elements distribution was uniform in the fibers, confirming a good homogeneity of the fibers.
Fibrous porous ceramics play a vital role in the field of thermal protection systems. In this work, novel lightweight Y 2 Si 2 O 7 fibrous porous ceramics were successfully prepared based on Y 2 Si 2 O 7 fibrous membranes by molding method. The effects of mechanical dispersion speed and heat treatment temperature on the properties of Y 2 Si 2 O 7 fibrous porous ceramics were characterized. The results revealed that benefiting from the appropriate fiber length, the ceramics had a better performance at a mechanical dispersion speed of 4000 revolutions per minute. The density, shrinkage, and compressive strength of the ceramics increased, but the porosity decreased slightly with the increasing heat treatment temperature. The prepared Y 2 Si 2 O 7 fibrous porous ceramics exhibited favorable properties like low density (0.37 g/cm 3 ), high porosity (90.56%), good high-temperature resistance (∼1350 °C), and low thermal conductivity (∼0.12 W m −1 K −1 at 27 °C, ∼0.566 W m −1 K −1 at 1000 °C). These properties indicate that Y 2 Si 2 O 7 fibrous porous ceramics could be a promising candidate as thermal insulation materials in high-temperature environments.
Fibrous porous ceramics have been receiving more and more applications in the thermal protection field of vehicles. In this study, we prepared Y 2 Si 2 O 7 fibrous porous ceramics (YFPCs) from Y 2 Si 2 O 7 fibrous membranes via the molding method. The influence of sintering time and binder concentration on the properties of YFPCs was studied, and the oxyacetylene ablation behavior with different heat fluxes was also investigated. The results showed that YFPCs obtained at 2 h sintering time had a stable component composition and constant mechanical strength . YFPCs prepared at 40 wt% binder concentration had the maximum density and compressive strength , 0.47 g/cm 3 and 0.68 MPa, respectively. The as-prepared ceramics exhibited favorable ablation resistance after oxyacetylene ablation for 120 s. The minimum linear ablation rate was 2.02 μm/s when the ablated surface temperature reached 1390 °C. When the surface temperature increased to 1872 °C and 2200 °C, the fibers on the ablated surface began to melt, and the linear ablation rate increased to 9.63 μm/s and 77.63 μm/s, respectively.
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