Key Takeaways & Executive Findings
- •• • Aqueous slurry-based IVI (CHS) achieved a ZrB2 phase volume fraction of 25 vol.% after a single cycle, a 47% increase over phenolic/acetone-based CPS, while cutting processing time by 49%, directly addressing the low ceramic loading bottleneck of conventional IVI. • • After CVI, CVI-CHS exhibited a room-temperature compressive strength of 106.78±10.53 MPa, a 28% improvement over CVI-CPS, indicating enhanced load-bearing capability for thermal protection structures. • • Both composites displayed high strain tolerance (1.32%±0.018% for CVI-CHS and 1.07%±0.34% for CVI-CPS) with low flexural modulus (13.00±2.41 and 13.52±6.99 GPa), enabling damage tolerance under mechanical stress. • • CVI-CPS achieved superior X-band EMI shielding of 34–36 dB versus 22–27 dB for CVI-CHS, with both showing improved shielding up to 600°C, offering tunable electromagnetic functionality for aerospace applications.
Abstract
Continuous carbon fiber-reinforced ZrB2-SiC ceramic matrix composites are promising thermal protection materials for hypersonic vehicles and reusable spacecraft. Although injection-assisted vacuum impregnation (IVI) offers advantages such as shorter processing cycles, lower costs, and reduced fiber damage compared to conventional methods, phenolic/acetone-based IVI systems yield composites (designated as CPS) with limited ceramic contents. To address this, an aqueous slurry-based IVI approach was developed, producing composites designated as CHS. After a single IVI cycle, CHS achieved a ZrB2 phase volume fraction of 25 vol.%, 47% higher than CPS, while reducing processing time by 49%. After chemical vapor infiltration, CVI-CHS composite exhibited a room-temperature compressive strength of 106.78±10.53 MPa, representing a 28% improvement over CVI-CPS. Crack propagation analysis revealed discontinuous zigzag patterns under compression, dominated by fiber bridging and pull-out energy dissipation mechanisms. Flexural results revealed both composites retain considerable strength (111.15±12.46 and 83.15±12.03 MPa) along with low flexural modulus (13.00±2.41 and 13.52±6.99 GPa) and high strain tolerance (1.32%±0.018% and 1.07%±0.34%). It is attributed to the anisotropy of fiber preforms and the elastic modulus mismatch among different phases, which hindered effective constraint of fibers by the matrix and, in turn, facilitated mitigation of stress concentration. Additionally, CVI-CPS demonstrated superior X-band electromagnetic interference (EMI) shielding (34–36 dB) compared to CVI-CHS (22–27 dB), resulting from synergistic effects between pyrolitic and deposited carbon in the matrix of the former. Both composites showed enhanced EMI shielding efficiency with increasing temperature up to 600°C. This eco-friendly aqueous IVI strategy enables high-performance, cost-effective thermal protection materials with higher ceramic loading and tunable multifunctional properties.
1. Introduction
Ultra-high temperature ceramic matrix composites (UHTCMCs) are critical for next-generation hypersonic vehicles, reusable spacecraft, and nuclear fusion devices, where they must simultaneously provide ablation/oxidation resistance, thermo-mechanical load bearing, and long-term structural integrity. Among these, continuous carbon fiber-reinforced ZrB2-SiC composites (Cf/ZrB2-SiC) are particularly attractive due to their lightweight, refractory nature, good ablation resistance, low cost, and excellent mechanical properties. However, their development is hindered by two major challenges: fiber structural degradation during high-temperature densification and the high cost and long cycles of manufacturing. Existing fabrication methods each have inherent limitations: polymer infiltration and pyrolysis (PIP) requires multiple cycles and suffers from low solid loading; chemical vapor infiltration (CVI) is inefficient for high-molecular-weight species; and reactive melt infiltration (RMI) can damage fibers. Injection-assisted vacuum impregnation (IVI) offers a promising alternative with shorter cycles and reduced fiber damage, but conventional phenolic/acetone-based systems yield composites with limited ceramic content, restricting their performance.
This study introduces an aqueous slurry-based IVI approach to overcome the ceramic loading limitation. By replacing the organic solvent with water, the new method (CHS) achieves a significantly higher ZrB2 volume fraction (25 vol.%) after a single impregnation cycle, a 47% improvement over the conventional CPS system, while also reducing processing time by 49%. This eco-friendly strategy not only enhances ceramic loading but also enables tunable multifunctional properties, including improved compressive strength and electromagnetic interference shielding. The findings demonstrate that aqueous IVI is a cost-effective and scalable route for producing high-performance Cf/ZrB2-SiC composites, addressing the critical bottleneck of low ceramic content in traditional IVI and offering a viable path for industrial adoption in thermal protection systems.
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CHEN Li, YANG Hailing, ZOU Ji, LIU Jingjing, WANG Weimin, FU Zhengyi (2026). Rapid Fabrication of Cf/ZrB2-SiC Composites with Multifunctional Properties via Aqueous Injection-Assisted Vacuum Impregnation. SCIENCE CHINA Materials. https://doi.org/10.1007/s40843-025-3487-x
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Frequently Asked Questions
What is the primary advantage of the aqueous slurry-based IVI (CHS) over the conventional phenolic/acetone-based IVI (CPS) in terms of ceramic loading and processing efficiency?
The aqueous slurry-based IVI (CHS) achieves a ZrB2 phase volume fraction of 25 vol.% after a single impregnation cycle, which is 47% higher than that of CPS. Additionally, the processing time is reduced by 49%, demonstrating a significant improvement in both ceramic loading and manufacturing efficiency.
How does the compressive strength of CVI-CHS compare to CVI-CPS, and what does this imply for structural applications?
CVI-CHS exhibits a room-temperature compressive strength of 106.78±10.53 MPa, which is 28% higher than that of CVI-CPS. This improvement suggests that the higher ceramic content in CHS enhances load-bearing capability, making it more suitable for structural applications under compressive loads.
What are the flexural properties of the composites, and how do they relate to the material's damage tolerance?
Both composites retain considerable flexural strength (111.15±12.46 MPa for CVI-CHS and 83.15±12.03 MPa for CVI-CPS) with low flexural modulus (13.00±2.41 GPa and 13.52±6.99 GPa, respectively) and high strain tolerance (1.32%±0.018% and 1.07%±0.34%). These properties indicate that the composites can undergo significant deformation before failure, which is beneficial for mitigating stress concentration and enhancing damage tolerance.
Why does CVI-CPS exhibit superior electromagnetic interference (EMI) shielding compared to CVI-CHS, and what is the practical significance?
CVI-CPS demonstrates superior X-band EMI shielding (34–36 dB) compared to CVI-CHS (22–27 dB). This is attributed to the synergistic effects between pyrolitic and deposited carbon in the matrix of CVI-CPS. The higher shielding effectiveness makes CVI-CPS more suitable for applications requiring electromagnetic compatibility, such as in aerospace electronics.
How does the EMI shielding efficiency of both composites change with temperature, and what are the implications for high-temperature applications?
Both composites show enhanced EMI shielding efficiency with increasing temperature up to 600°C. This temperature-dependent behavior is crucial for thermal protection materials that operate in high-temperature environments, as it ensures consistent electromagnetic shielding performance under service conditions.
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