Reducing sintering temperature and regulating properties via forming crystalline-amorphous dual-phase microstructure
发布时间：2026-05-17
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发表刊物：Journal of Alloys and Compounds
摘要：In this study, we aim to lower the sintering temperature and improve the overall mechanical properties of Al2O3-based and mullite-based ceramics by incorporating an amorphous SiO2 component. Two types of Al2O3-SiO2 precursor powders were synthesized via wet chemical methods and they were composed of Al2O3-SiO2 glass and α-Al2O3 submicron particles covered by amorphous SiO2, respectively. During sintering, a solid-state reaction occurred in the Al2O3-SiO2 glass, resulting in the formation of mullite nanograins. In contrast, no reaction was observed between α-Al2O3 submicron particles and the amorphous SiO2. Sintering temperatures of the ceramics were markedly reduced due to the viscous flow of the amorphous SiO2 component. Both ceramics exhibited a crystalline-amorphous dual-phase (CADP) microstructure, consisting of stiff crystallites dispersed in a soft amorphous SiO2 matrix. The fracture toughness of the Al2O3-SiO2 ceramic was measured at 6.57 MPa·m1/2, higher than the typical range for monolithic Al2O3 (3.0–4.5 MPa·m1/2). In contrast, the fracture toughness of the mullite-SiO2 ceramic was determined to be 2.42 MPa·m1/2, which lies well within the established range for monolithic mullite (2.0–2.5 MPa·m1/2). The thermal conductivity of the Al2O3-SiO2 and mullite-SiO2 ceramics was measured at 5.702 and 2.646 W·m−1·K−1, respectively. In contrast, high-purity monolithic Al2O3 and mullite exhibit much higher thermal conductivities—typically ∼30.0 and ∼5.0 W·m−1·K−1, respectively. This substantial reduction in thermal conductivity is attributed to the abundant crystalline-amorphous interfaces present in the composite microstructures. The Al2O3-SiO2 ceramic exhibited low permittivity (ε'≈2.55–3.05) and dielectric loss (tan δ≈0.01 at 12–16 GHz). In contrast, the mullite-SiO2 ceramic displayed a narrower permittivity range (ε'≈2.7–2.9). Additionally, it exhibited a loss tangent (tan δ) as low as 0.005.
合写作者：Zihua Lei, Xiaoyuan Li, Yang Li
第一作者：Mingxi Deng
通讯作者：Le Fu*, Gemei Cai*
卷号：1069
期号：31
页面范围：188626
是否译文：否
发表时间：2026-05-17
发布期刊链接：https://www.sciencedirect.com/science/article/pii/S0925838826026952?dgcid=author