纳秒脉冲激光熔覆温度场计算及薄膜飞溅机制分析  

Calculatation for Nano-Second Pulsed Laser Cladding Temprature Field and Analysis of Thin Film Removal Mechanism

作　　者：张永彬[1] 宾韧[1] 郎定木[2] 

机构地区：[1]表面物理与化学重点实验室,四川绵阳621707 [2]中国工程物理研究院,四川绵阳621900

出　　处：《应用激光》2012年第6期464-468,共5页Applied Laser

基　　金：中国工程物理研究院发展基金资助项目(项目编号:20100203027)

摘　　要：实验上采用磁控溅射在铀、不锈钢、铝基底上分别沉积钼、铌、铝等薄膜后采用纳秒激光熔覆,薄膜发生飞溅,未能形成熔覆层。针对这一问题,采用有限元方法分析了脉冲激光作用的温度场,并对瞬时热膨胀造成薄膜垂直于表面的运动进行了分析。计算以及分析结果表明:由于界面热阻,纳秒激光熔覆薄膜与基底存在较大的温度差,在本例计算铝薄膜与基底温差超过450℃。瞬时热膨胀导致薄膜具有向外的速度以及动能。当薄膜动能大于拉伸断裂所需要克服的弹性以及塑性变形能量,薄膜将发生飞溅。理论分析还表明存在一个临界的光束尺寸,当光束小于该尺寸,薄膜不会发生飞溅,熔覆能够发生,对于准分子激光,光束尺寸达微米量级薄膜不会飞溅。Thin films of molybdenum, niobium, aluminium were prepared by magetron sputtering, nano-second laser was employed to clad these thin films on diferent substrates, but the cladding layers wrer not formed, thin films were removed by laser. In order to explain this question, temperature fields were calculated using fern method, kinematic of thin film caused by instantaneous thermo expansion was analysed based on Newton dynamic. Results show there is temprature gap between thin film and substrate due to surface thermo ressistance, in this example, the temperature differences are more than 450 ~C. Instantaneous thermo expansion leads thin film abtained velocity and kinetic energy. If the kinetic energy is greater than elatic and plastic energy of thin film fracture limite, thin film would be removed. Theoretic analysis also shows there is a critical beam size, less than the critical beam size, the thin film would not be removed, for eximer pulsed laser the criical beam size is about micrometer.

关 键 词：激光 温度场 熔覆 机制 

分 类 号：TG156.99[金属学及工艺—热处理]