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<p>The structurization and mechanical properties of AlN-based composite ceramics were studied. Composite samples were prepared from powder mixtures containing 3% diamond powder of various grain sizes and 5% carbon black by hot pressing at 1900–1920°C under a pressure of 12–13 MPa. X-ray diffraction revealed the main phases in the composites, such as AlN, Al<sub>3</sub>(O, N)<sub>4</sub> and graphitic carbon, while scanning electron microscopy was employed to determine their grain sizes and distribution within the structure. Analysis of all composites showed a uniform distribution of graphite inclusions with an average size of 0.2–5 μm over the entire sample surface, with smaller inclusions corresponding to finer diamond powder in the starting mixture. Hardness measurements with a Vickers indenter were performed at a load of 49 N, and fracture toughness was calculated from the measured lengths of radial cracks emanating from the indentation corners. At comparable densities (3.23–3.24 g/cm<sup>3</sup>), the highest hardness (<i>HV</i> = 11.79 ± 0.38 GPa) and fracture toughness (<i>K</i><sub>1c</sub> = 7.01 ± 0.04 MPa∙m<sup>0.5</sup>) were shown by materials with an average graphite grain size of approximately 1 μm, corresponding to the composites prepared with 1/0 μm diamond grains in the starting powder mixture. It was established that an increase in the grain size of the starting diamond powder and, accordingly, an increase in the grain size of the graphite phase in the composite resulted in decreased mechanical properties. Additionally, since the material containing 5% carbon black had lower density (3.19 g/cm<sup>3</sup>) compared to other composites, it exhibited the lowest mechanical properties: <i>HV</i> = 7.6 ± 0.31 GPa and <i>K</i><sub>1c</sub> = 4.28 ± 0.34 MPa∙m<sup>0.5</sup>.</p>

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Structure and Mechanical Properties of Aluminum Nitride Composites with Diamond Powder and Carbon Black Additives

  • 期刊论文

  • 发表日期：

    2025年11月1日

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  • T. B. Serbeniuk,
  • T. O. Prikhna,
  • V. B. Sverdun,
  • V. E. Moshchil,
  • M. V. Karpets,
  • H. D. Ilnytska,
  • A. A. Marchenko,
  • L. O. Polikarpova,
  • V. V. Bilorusets,
  • S. P. Starik

摘要

The structurization and mechanical properties of AlN-based composite ceramics were studied. Composite samples were prepared from powder mixtures containing 3% diamond powder of various grain sizes and 5% carbon black by hot pressing at 1900–1920°C under a pressure of 12–13 MPa. X-ray diffraction revealed the main phases in the composites, such as AlN, Al3(O, N)4 and graphitic carbon, while scanning electron microscopy was employed to determine their grain sizes and distribution within the structure. Analysis of all composites showed a uniform distribution of graphite inclusions with an average size of 0.2–5 μm over the entire sample surface, with smaller inclusions corresponding to finer diamond powder in the starting mixture. Hardness measurements with a Vickers indenter were performed at a load of 49 N, and fracture toughness was calculated from the measured lengths of radial cracks emanating from the indentation corners. At comparable densities (3.23–3.24 g/cm3), the highest hardness (HV = 11.79 ± 0.38 GPa) and fracture toughness (K1c = 7.01 ± 0.04 MPa∙m0.5) were shown by materials with an average graphite grain size of approximately 1 μm, corresponding to the composites prepared with 1/0 μm diamond grains in the starting powder mixture. It was established that an increase in the grain size of the starting diamond powder and, accordingly, an increase in the grain size of the graphite phase in the composite resulted in decreased mechanical properties. Additionally, since the material containing 5% carbon black had lower density (3.19 g/cm3) compared to other composites, it exhibited the lowest mechanical properties: HV = 7.6 ± 0.31 GPa and K1c = 4.28 ± 0.34 MPa∙m0.5.