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Prof. Jiaxu ZHANG

State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing

Research Publications & English Decoded Briefs

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SCIENCE CHINA Materials2026DOI: 10.1007/s40843-025-3588-2

In-situ polymer-derived SiOCnws-Cf/SiC(rGO) composites: a potential candidate for EMI shielding and thermal management

The rapid evolution of aerospace technology necessitates the development of multi-functional composites that combine light weight, mechanical robustness, thermal protection/insulation, and electromagnetic interference (EMI) shielding. C/SiC porous ceramic composites are promising for thermal protection in hypersonic vehicles. Here, we report a facile strategy to fabricate Cf/SiC composite polymer-derived ceramics (PDCs) via re-pyrolysis of high-energy ball-milled polycarbosilane-vinyltriethoxysilane-graphene oxide (PVG) with Cf/SiC(rGO)p blend interleaves. In-situ generated honeycomb-like cellular structures and non-directional channels reduce density and increase porosity. High-quality SiO2 joints, formed from Si-dangling bonds, strengthen interfacial bonding via a brazing effect, while in-situ SiOC nanowires (SiOCnws) create a hierarchically enhanced network, improving fracture toughness and crack resistance. Multi-scale interfacial/dipole polarization enhances EMI shielding. The optimized Cf(0.2)/SiC(rGO) composite exhibits low density (1.49 g cm−3), high fracture toughness (6.32 MPa m1/2), hardness (7.18 GPa), compressive strength (72.67 MPa), and EMI shielding effectiveness of 58.31 dB. It maintains structural stability under butane blowtorch ablation at ~1300 °C for 3600 s. Porous variants show thermal conductivity of 0.211 W m−1 K−1 with 69.74% porosity. These multi-functional composites are promising for thermal protection systems in aerospace applications.

The Chinese Journal of Process Engineering2026DOI: 10.12034/j.issn.1009-606X.225246

Experimental Study on Classification Performance of Multi-Arm Vortex Separator

The development of efficient catalyst classification technologies is crucial for optimizing fluid catalytic cracking (FCC) and catalytic pyrolysis coupling processes, where distinct particle size distributions are required for different reaction pathways. In this study, a large-scale cold-model experimental platform of a multi-arm vortex separator is established to explore the influence of operating conditions on classification behavior. Systematic experiments are conducted by changing ejection gas velocity (8~20 m/s), inlet particle concentration (30~70 g/m3), and bed linear velocity (0.15~0.25 m/s). The results demonstrate that ejection gas velocity governs classification sharpness by controlling the entrainment of fines within the coarse fraction. The increase in ejection gas velocity enlarges the upward axial gas velocity inside the device, thereby enhancing the entrainment effect on particles near the vortex arm outlets. Increasing the ejection gas velocity from 12 to 16 m/s reduces proportion of fine particles in coarse components from 14% to 12%. The inlet particle concentration imposes competing effects on classification performance: while higher concentrations promote agglomeration and modify turbulence distribution, excessive loading intensifies fine-particle entrainment, thereby diminishing classification selectivity. The system maintains stable pressure drop characteristics under different bed linear velocities, with the pressure drop increasing by maximum of about 15% when the bed linear velocity is raised from 0.15 m/s to 0.25 m/s. Analysis of grade efficiency curves reveals classical S-shaped profiles with cut sizes (dc50) shifting under different operating regimes. Higher particle concentrations reduces dc50, favoring fine-particle removal, while higher ejection gas velocities enlarge dc50, moving the classification boundary toward larger sizes. These findings confirm the synergistic effect of ejection gas velocity and inlet concentration, highlighting that rational parameter matching can simultaneously improve efficiency and selectivity. Beyond the experimental findings, this work emphasizes the broader applicability of multi-arm vortex separators in refining and petrochemical processes. By enabling precise adjustment of particle size distribution, the system offers a promising pathway for enhancing catalyst utilization, extending catalyst lifetime, and facilitating process intensification in coupled FCC-pyrolysis units.

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