Correlations between porosity, thermal conductivity, and mechanical strength in bi-layered ceramics with varying carbon black contents

Mohamed Lokman Jalaluddin; Umar Al-Amani Azlan; Mohd Warikh Abd Rashid; Muchlis; Mohamed Lokman Jalaluddin; Umar Al-Amani Azlan; Mohd Warikh Abd Rashid; Muchlis

doi:10.3934/matersci.2025043

AIMS Materials Science

2025, Volume 12, Issue 5: 965-974. doi: 10.3934/matersci.2025043

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Research article

Correlations between porosity, thermal conductivity, and mechanical strength in bi-layered ceramics with varying carbon black contents

1.
Faculty of Industrial and Manufacturing Technology and Engineering, Universiti Teknikal Malaysia Melaka, Malaysia
2.
Faculty of Science and Information Technology, Universitas AKPRIND Indonesia, Jl. Kalisahak No.28, Klitren, Kec. Gondokusuman, Kota Yogyakarta, Daerah Istimewa Yogyakarta 55222, Indonesia

Received: 18 August 2025 Revised: 15 September 2025 Accepted: 18 September 2025 Published: 24 September 2025

This paper focuses on the correlations between porosity, thermal conductivity, and mechanical strength in bi-layered ceramics with varying carbon black (CB) contents. Dense/porous bi-layered ceramics were synthesized via a solid-state reaction using feldspar, silica, and kaolinite powders, with CB incorporated into the porous bottom layer at 1–5 wt.% as a pore-forming agent, while the dense top layer remained CB-free. All specimens were fabricated under identical processing conditions, which involved uniaxial pressing at 20 MPa and sintering at 1175 ℃ for 3 h. A non-linear relationship was established between the CB content and the material properties. The optimum composition, 3 wt.% CB, exhibited the highest porosity (9.16%), the lowest thermal conductivity (1.483 W/m·K), and the maximum flexural strength (49.73 MPa), thus representing the best compromise between insulation efficiency and mechanical strength. At lower CB contents (1–2 wt.%), insufficient pore development limited the reduction in thermal conductivity, whereas excessive CB loadings (4–5 wt.%) produced diminished porosity and corresponding decreases in strength. These results highlight that controlled CB burnout during sintering governs pore evolution in a manner that optimizes phonon scattering and stress redistribution. Overall, this study demonstrates that precise control of pore-former content is critical to tailor multifunctional properties in bi-layered ceramics and establishes a design guideline for developing lightweight ceramic systems with superior thermal and structural performances.
- bi-layered ceramics,
- porosity,
- thermal conductivity,
- flexural strength,
- carbon black
Citation: Mohamed Lokman Jalaluddin, Umar Al-Amani Azlan, Mohd Warikh Abd Rashid, Muchlis. Correlations between porosity, thermal conductivity, and mechanical strength in bi-layered ceramics with varying carbon black contents[J]. AIMS Materials Science, 2025, 12(5): 965-974. doi: 10.3934/matersci.2025043

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Abstract

This paper focuses on the correlations between porosity, thermal conductivity, and mechanical strength in bi-layered ceramics with varying carbon black (CB) contents. Dense/porous bi-layered ceramics were synthesized via a solid-state reaction using feldspar, silica, and kaolinite powders, with CB incorporated into the porous bottom layer at 1–5 wt.% as a pore-forming agent, while the dense top layer remained CB-free. All specimens were fabricated under identical processing conditions, which involved uniaxial pressing at 20 MPa and sintering at 1175 ℃ for 3 h. A non-linear relationship was established between the CB content and the material properties. The optimum composition, 3 wt.% CB, exhibited the highest porosity (9.16%), the lowest thermal conductivity (1.483 W/m·K), and the maximum flexural strength (49.73 MPa), thus representing the best compromise between insulation efficiency and mechanical strength. At lower CB contents (1–2 wt.%), insufficient pore development limited the reduction in thermal conductivity, whereas excessive CB loadings (4–5 wt.%) produced diminished porosity and corresponding decreases in strength. These results highlight that controlled CB burnout during sintering governs pore evolution in a manner that optimizes phonon scattering and stress redistribution. Overall, this study demonstrates that precise control of pore-former content is critical to tailor multifunctional properties in bi-layered ceramics and establishes a design guideline for developing lightweight ceramic systems with superior thermal and structural performances.

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