Brittle fracture control of 4H-SiC via laser-textured surfaces: Combined experimental and atomistic study

YQ Zhou and KZ Xu and YH Gao and ZN Yu and FL Zhu, DIAMOND AND RELATED MATERIALS, 158, 112697 (2025).

DOI: 10.1016/j.diamond.2025.112697

Silicon carbide (SiC) is a covalently bonded crystal with a hardness second only to diamond, and its combination of extreme hardness and chemical inertness presents significant challenges for precision machining. A laser-assisted strategy involving periodic surface texturing is proposed to improve material removal behavior. By comparing the surface morphology and crystal structure evolution of 4H-SiC under different laser powers, 4500 mW is identified as the optimal setting for generating uniform surface grooves without cracks and backfilling of the remelted material. Scratching experiments reveal periodic fluctuations in scratching force, coefficient of friction (COF), and acoustic emission (AE) signals, with the fluctuation frequency determined by the ratio of scratching speed to texture spacing. Increased average scratching force, COF, and AE intensity are observed on textured surfaces, particularly at smaller texture spacing. Molecular dynamics simulations uncover that the laser-ablated textures guide brittle fracture propagation, reduce internal strain accumulation, and enhance material removal efficiency while minimizing subsurface damage. Moreover, the simulations reveal that periodic brittle fracture events are the primary cause of the observed signal fluctuations, providing mechanistic insight into the role of surface textures in fracture- dominated material removal. These findings establish a promising pathway for high-efficiency, low-damage processing of covalently bonded crystals such as 4H-SiC.

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