Numerical analysis of Nd:YAG pulsed laser polishing CVD self-standing diamond film
Numerical analysis of Nd:YAG pulsed laser polishing CVD self-standing diamond film
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DOI：
10.3901/cjme.2013.01.121
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发表时间：
2013-02
影响因子：
4.2
通讯作者：
F. Xu;Haifeng Hu;D. Zuo;Chun Xu;Z. Qing;Min Wang
中科院分区：
文献类型：
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作者：
F. Xu;Haifeng Hu;D. Zuo;Chun Xu;Z. Qing;Min Wang
化学气相沉积（CVD）金刚石薄膜在高科技领域具有广阔的应用前景。但多晶CVD自支撑金刚石厚膜表面粗糙、厚度不均匀，影响了其广泛应用。激光抛光是一种有效的金刚石自支撑膜的抛光方法。目前，激光抛光的研究主要集中在实验研究方面，而理论模型的揭示和抛光过程的预测尚属空白。基于激光热传导理论，建立了激光抛光金刚石的有限元模型，对激光抛光金刚石的机理进行了仿真分析。还对Nd：YAG脉冲激光平滑金刚石厚膜进行了实验研究。仿真结果与实验结果吻合较好。研究了Nd：YAG脉冲激光在不同入射角和参数下的温度场和热应力场。金刚石厚膜表面的粗糙度导致了温度场的不均匀性。金刚石膜的峰温远高于谷温，导致金刚石厚膜的平整。研究了激光参数对石墨过渡层厚度和表面粗糙度的影响。结果表明，高功率密度激光使石墨化后的金刚石表面迅速升温、蒸发和升华。大入射角、适当的激光脉冲能量、大重复频率和适当的激光脉冲宽度组合可以获得良好的金刚石厚膜抛光质量。研究结果为激光抛光金刚石薄膜提供了高效、高质量的理论依据。
Chemical vapor deposited (CVD) diamond film has broad application foreground in high-tech fields. But polycrystalline CVD self-standing diamond thick film has rough surface and non-uniform thickness that adversely affect its extensive applications. Laser polishing is a useful method to smooth self-standing diamond film. At present, attentions have been focused on experimental research on laser polishing, but the revealing of theoretical model and the forecast of polishing process are vacant. The paper presents a finite element model to simulate and analyze the mechanism of laser polishing diamond based on laser thermal conduction theory. The experimental investigation is also carried out on Nd:YAG pulsed laser smoothing diamond thick film. The simulation results have good accordance with the results of experimental results. The temperature and thermal stress fields are investigated at different incidence angles and parameters of Nd:YAG pulsed laser. The pyramidal-like roughness of diamond thick film leads to the non-homogeneous temperature fields. The temperature at the peak of diamond film is much higher than that in the valley, which leads to the smoothing of diamond thick film. The effect of laser parameters on the surface roughness and thickness of graphite transition layer is also carried out. The results show that high power density laser makes the diamond surface rapid heating, evaporation and sublimation after its graphitization. It is also found that the good polish quality of diamond thick film can be obtained by a combination of large incident angle, moderate laser pulsed energy, large repetition rate and moderate laser pulse width. The results obtained here provide the theoretical basis for laser polishing diamond film with high efficiency and high quality.