Laser-assisted generation of self-assembled microstructures on stainless steel
Laser-assisted generation of self-assembled microstructures on stainless steel
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DOI：
10.1007/s00339-008-4646-4
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发表时间：
2008-05
期刊：
影响因子：
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通讯作者：
R. Lloyd;A. Abdolvand;M. Schmidt;P. Crouse;D. Whitehead;Zhu Liu;Lin Li
中科院分区：
文献类型：
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作者：
R. Lloyd;A. Abdolvand;M. Schmidt;P. Crouse;D. Whitehead;Zhu Liu;Lin Li
利用 Nd:YVO4 激光器（波长 532 nm，脉冲持续时间 8 ns，重复频率 30 kHz）和 Nd:YAG 激光器（波长 1064 nm，脉冲持续时间 7 ns，重复频率 25 kHz），发现在不锈钢等金属靶材的脉冲激光烧蚀过程中，周期性结节 形成了平均周期为~30 至~50 μm 的微结构（微锥）。该周期取决于累积激光脉冲的数量，并且与激光波长无关。研究发现，以~12 J/cm2 的激光注量、~1.5 GW/cm2 的强度将每点 1500 个脉冲（比之前报道的数量要少）发射到目标表面位置后，就会形成微锥。结构形成所需的初始反馈机制归因于熔体的流体动力学不稳定性。除此之外，研究还表明，结构沿着入射激光辐射的光轴生长。我们证明可以在不同角度产生高度规则的结构，这是以前在金属表面上无法令人满意地呈现的结构。还研究了影响因素，例如激光束的入射角以及改变激光束在目标表面上扫描的方式时可以形成的结构。
Utilising a Nd:YVO4laser (wavelength of 532 nm, pulse duration of 8 ns, repetition rate of 30 kHz) and a Nd:YAG laser (wavelength of 1064 nm, pulse duration of 7 ns, repetition rate of 25 kHz), it was found that during the pulsed laser ablation of metal targets, such as stainless steel, periodic nodular microstructures (microcones) with average periods ranging from ∼30 to ∼50 μm were formed. This period depends on the number of accumulated laser pulses and is independent of the laser wavelength. It was found that the formation of microcones could occur after as little as 1500 pulses/spot (a lower number than previously reported) are fired onto a target surface location at laser fluence of ∼12 J/cm2, intensity of ∼1.5 GW/cm2. The initial feedback mechanism required for the formation of structures is attributed to the hydrodynamic instabilities of the melt. In addition to this, it has been shown that the structures grow along the optical axis of the incoming laser radiation. We demonstrate that highly regular structures can be produced at various angles, something not satisfactorily presented on metallic surfaces previously. The affecting factors such as incident angle of the laser beam and the structures that can be formed when varying the manner in which the laser beam is scanned over the target surface have also been investigated.