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<p>Polycrystalline diamond (PCD) is the most widely used superhard material to efficiently break the rocks in oil and gas exploration and deep-earth scientific exploration. As the exploration depth exceeds 10,000&#xa0;m, the downhole rock lithologies are becoming increasingly harsh and difficult to drill, requiring better properties than the existing PCD materials in terms of hardness, toughness, and thermal stability. This study used 1 um diamond particles as the raw material, with fullerene (C<sub>60</sub>) as the binder, to synthesize a novel PCD/C<sub>60</sub> composite under sintering conditions of 15 GPa and 2000&#xa0;°C. The existing PCD materials sintered with the binder systems of metal cobalt, silicon carbide nanowires, and calcium carbonate were used as benchmarks. X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy were employed to characterize the microstructure of synthesized PCD materials while the Vickers hardness testing and thermogravimetric analysis were conducted to investigate the materials’ hardness, fracture toughness and thermal stability. The results showed that the new PCD/C<sub>60</sub> composite had a Vickers hardness of 83.2 ± 5.5 GPa, a fracture toughness of 18.9 ± 1.9&#xa0;MPa·m<sup>0.5</sup>, and a temperature of 896.8&#xa0;°C for maximum weight loss rate, which exhibited the best potential for the deep-earth scientific exploration from the perspective of a good balance of various properties, especially excellent fracture toughness. Based on the microstructural characteristics, the properties of PCD/C<sub>60</sub> composite were attributed to the mixed arrangement of three types of strongly bonded interfaces, and the filling of the diamond voids by high-strength <i>sp</i><sup><i>2</i></sup><i>-sp</i><sup><i>3</i></sup> amorphous carbon.</p> Graphical Abstract <p></p>

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Synthesis of polycrystalline diamond using C60 as binder for deep-earth scientific exploration

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年7月9日

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  • Wei Liu,
  • Fengjiao Li,
  • Jiawei Zhang,
  • Deli Gao,
  • Xiaohui Yu

摘要

Polycrystalline diamond (PCD) is the most widely used superhard material to efficiently break the rocks in oil and gas exploration and deep-earth scientific exploration. As the exploration depth exceeds 10,000 m, the downhole rock lithologies are becoming increasingly harsh and difficult to drill, requiring better properties than the existing PCD materials in terms of hardness, toughness, and thermal stability. This study used 1 um diamond particles as the raw material, with fullerene (C60) as the binder, to synthesize a novel PCD/C60 composite under sintering conditions of 15 GPa and 2000 °C. The existing PCD materials sintered with the binder systems of metal cobalt, silicon carbide nanowires, and calcium carbonate were used as benchmarks. X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy were employed to characterize the microstructure of synthesized PCD materials while the Vickers hardness testing and thermogravimetric analysis were conducted to investigate the materials’ hardness, fracture toughness and thermal stability. The results showed that the new PCD/C60 composite had a Vickers hardness of 83.2 ± 5.5 GPa, a fracture toughness of 18.9 ± 1.9 MPa·m0.5, and a temperature of 896.8 °C for maximum weight loss rate, which exhibited the best potential for the deep-earth scientific exploration from the perspective of a good balance of various properties, especially excellent fracture toughness. Based on the microstructural characteristics, the properties of PCD/C60 composite were attributed to the mixed arrangement of three types of strongly bonded interfaces, and the filling of the diamond voids by high-strength sp2-sp3 amorphous carbon.

Graphical Abstract