Abstract
With high activity h-BN powders as raw materials and without the using of any sintering additives, AlN–BN composite ceramics with 0–30 vol% were prepared by hot-pressing sintering in N2 at 1850 °C. Effect of h-BN content on the microstructure and properties of the composite ceramics was investigated. The results show that fully dense composite ceramics with h-BN content up to 20 vol% can be obtained and all composites show a fine-grain-microstructure with clean and clear boundaries. No “card room structure” of h-BN was formed in the samples. With the increasing h-BN content, the composites show a decreased bending strength, fracture toughness, Vickers hardness, thermal conductivity and dielectric constant. The application of high activity raw materials produces a significant grain-refinement strengthening effect and makes the composites exhibit a much higher strength and toughness compared with the results reported by other researchers. Due to the absence of sintering additive, the composite ceramics also show a quite low dielectric loss at both low and high frequency. An optimal comprehensive properties are obtained for the AlN-20 vol% BN composite: bending strength of 410 ± 21 MPa, fracture toughness of 4.21 ± 0.19 MPa·m1/2, Vickers hardness of 7.7 ± 0.2 GPa, thermal conductivity of 46.6 W·m−1·K−1, dielectric constant of 7.4 (1 MHz) and 7.48 (18 GHz), dielectric loss of 6.7 × 10−4 (1 MHz) and 6.18 × 10−3 (18 GHz).
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Acknowledgments
This work was supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT), IRT1146, and National Natural Science Foundation of China (U1232136).
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Jin, C., Wang, T., Pan, L. et al. Preparation and properties of sintering additive-free AlN–BN composite ceramics by hot-pressing sintering. J Mater Sci: Mater Electron 27, 2014–2021 (2016). https://doi.org/10.1007/s10854-015-3985-0
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DOI: https://doi.org/10.1007/s10854-015-3985-0