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激光与材料的能量耦合系数是研究激光与物质相互作用的基础。金属在空气中与激光相互作用时,其能量耦合系数远大于理论值。文中以金属铁为例,研究金属氧化膜对激光与材料的能量耦合系数的影响。利用温度场计算结果,结合铁在空气中的氧化规律,计算了激光辐照下氧化层厚度的增长及氧化放热的影响;利用多层膜反射理论,结合氧化层厚度变化,分析了氧化膜导致的激光吸收增强效应,并将计算结果与实验结果进行比较,结果符合很好,证明了模型的合理性。计算结果表明,激光辐照期间,氧化放热对温度场的贡献很小,就工程应用来说可以忽略,而氧化层带来的吸收增强效应影响较大,不能忽略,辐照一段时间后,激光耦合系数可以用氧化物的理论计算耦合率近似表征。
The energy coupling coefficient between laser and material is the basis for studying the interaction between laser and material. Metal in the air and laser interaction, the energy coupling coefficient is much larger than the theoretical value. In this paper, metal iron is taken as an example to study the effect of metal oxide film on the energy coupling coefficient between laser and material. Based on the calculation results of temperature field and the oxidation rule of iron in the air, the influence of laser irradiation on the growth of oxide layer thickness and oxidation exotherm was calculated. Based on the multilayer film reflection theory and the change of oxide layer thickness, The results show that the model is reasonable and the results are in good agreement with the experimental results. The calculated results show that during the laser irradiation, the contribution of the exothermic oxidation to the temperature field is very small, which is negligible for the engineering application. However, the absorption enhancement effect brought by the oxide layer has a great influence and can not be neglected. After a certain period of irradiation, The laser coupling coefficient can be approximately characterized by the theoretical calculated coupling rate of the oxide.