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<p>As a typical hard-brittle material, silicon nitride ceramics (Si<sub>3</sub>N<sub>4</sub>) offer promising potential for aerospace, national defense, and high-speed rail. However, high-performance abrasive machining of Si<sub>3</sub>N<sub>4</sub> is still a great challenge due to the ambiguity of material removal and subsurface damage mechanisms. This paper establishes a micro-scratch theoretical model of Si<sub>3</sub>N<sub>4</sub> based on the smoothed particle hydrodynamics (SPH) method. The influence of scratching depth and speed on material removal and crack propagation is studied. The distribution of effective plastic strain and subsurface crack is revealed. The scratching force and the material removal mode under different scratching conditions are analyzed. Furthermore, micro-scratch experiments of Si<sub>3</sub>N<sub>4</sub> under variable load are also conducted to verify the established model. The results show that the ductile removal of Si<sub>3</sub>N<sub>4</sub> can be achieved at the micro-scale. The critical depth of brittle-ductile transition obtained from the simulation is 4.2&#xa0;μm, consistent with the experiment. As the scratching depth reaches 6&#xa0;μm, the brittle fracture occurs, and a lateral crack with a length of 5.96&#xa0;μm formed. The depth of the subsurface crack is negatively correlated with the scratching speed. Therefore, controlling machining depth and speed is necessary to achieve ductile processing of Si<sub>3</sub>N<sub>4</sub>, which can avoid subsurface cracks and obtain better surface quality. These findings provide theoretical support for the high-efficiency and low-damage processing of Si<sub>3</sub>N<sub>4</sub>.</p>

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Characterization of Material Removal and Crack Propagation of Silicon Nitride Ceramics Under Mechanical Stressing

  • 期刊论文

  • 发表日期：

    2025年3月20日

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  • Ziyuan Liu,
  • Rong Su,
  • Ziguang Wang,
  • Yu Liu,
  • Shengfang Zhang

摘要

As a typical hard-brittle material, silicon nitride ceramics (Si3N4) offer promising potential for aerospace, national defense, and high-speed rail. However, high-performance abrasive machining of Si3N4 is still a great challenge due to the ambiguity of material removal and subsurface damage mechanisms. This paper establishes a micro-scratch theoretical model of Si3N4 based on the smoothed particle hydrodynamics (SPH) method. The influence of scratching depth and speed on material removal and crack propagation is studied. The distribution of effective plastic strain and subsurface crack is revealed. The scratching force and the material removal mode under different scratching conditions are analyzed. Furthermore, micro-scratch experiments of Si3N4 under variable load are also conducted to verify the established model. The results show that the ductile removal of Si3N4 can be achieved at the micro-scale. The critical depth of brittle-ductile transition obtained from the simulation is 4.2 μm, consistent with the experiment. As the scratching depth reaches 6 μm, the brittle fracture occurs, and a lateral crack with a length of 5.96 μm formed. The depth of the subsurface crack is negatively correlated with the scratching speed. Therefore, controlling machining depth and speed is necessary to achieve ductile processing of Si3N4, which can avoid subsurface cracks and obtain better surface quality. These findings provide theoretical support for the high-efficiency and low-damage processing of Si3N4.