Electrically Conductive and Mechanically Strong Graphene/Mullite Ceramic Composites for High-Performance...

Area of Science:

• Materials Science
• Nanotechnology
• Ceramic Engineering

Background:

• Advanced ceramic composites are crucial for applications requiring electromagnetic interference (EMI) shielding, especially in harsh environments.
• Achieving high electrical conductivity and mechanical strength simultaneously in ceramic composites remains a significant challenge.
• Reduced graphene oxide (rGO) incorporation offers potential for enhancing electrical properties but often requires high processing temperatures that can degrade performance.

Purpose of the Study:

• To develop lightweight, highly conductive, and strong mullite/reduced graphene oxide (rGO) composites for effective EMI shielding.
• To investigate the effect of a core-shell structured precursor on the sintering behavior and microstructure of rGO/mullite composites.
• To achieve high EMI shielding effectiveness with minimal rGO loading while maintaining excellent mechanical properties.

Main Methods:

• Fabrication of mullite composites with reduced graphene oxide (rGO) using spark plasma sintering (SPS) at 1200 °C.
• Utilized a core-shell structured γ-Al2O3@SiO2 powder as a precursor to induce transient viscous sintering.
• Characterized the electrical conductivity (in-plane and cross-plane), mechanical properties, and electromagnetic interference shielding effectiveness (SE) of the fabricated composites.

Main Results:

• Successfully fabricated lightweight, highly conductive, and strong mullite/rGO composites at a low sintering temperature of 1200 °C.
• The transient viscous sintering promoted an anisotropic structure, yielding exceptionally high in-plane electrical conductivity (696 S m⁻¹ at 0.89 vol% rGO) and low cross-plane conductivity.
• Achieved high EMI shielding effectiveness (>32 dB) across the K band with less than 1 vol% rGO, alongside improved strength and toughness.

Conclusions:

• The developed rGO/mullite composites demonstrate a promising pathway for creating efficient EMI shielding materials with superior mechanical performance.
• The low-temperature spark plasma sintering process using the specialized precursor effectively prevents detrimental reactions and creates desirable microstructural anisotropy.
• These composites are highly suitable for applications demanding robust EMI shielding in challenging environments without compromising structural integrity.