高反射率抗激光烧蚀涂层的制备及数值模拟研究

doi:10.15541/jim20150633

摘要/Abstract

摘要：

以TiO₂为颜料, 硅酸钾为粘结剂(以下简称KS-T), 采用空气喷涂的方法, 在铝基底上制备了一种抗激光烧蚀涂层。研究了粉体粒径大小、固含量、涂层厚度等因素对涂层反射率的影响, 获得了1064 nm激光波段下反射率达到96.8%的KS-T涂层。基于热传导方程建立三维有限元模型模拟材料的瞬态温度场分布, 测量激光辐照过程中铝基底的背底温度变化, 与模拟结果相比较, 发现KS-T涂层可以有效地保护基底不被激光烧蚀。模拟结果显示, 在辐照一段时间后, 样品的反射率出现了下降的现象, 分析了反射率下降的可能原因;计算结果还表明考虑界面热阻(ITR)后, 涂层/基底界面处出现一个明显的温降, 阻止热流向基底的传输, 从而使铝基底保持一个较低的温度。

关键词: 抗激光烧蚀涂层, 高反射率, 有限元模型, 界面热阻

Abstract:

An anti-laser-ablation coating using TiO₂as pigment and potassium silicate as binder (abbreviated as KS-T) was deposited on the aluminum alloy substrate by an air spray process. Factors influencing the reflectance of KS-T coating, including particle size, pigment volume concentration and coating thickness, were investigated. The reflectance of prepared KS-T coating could be up to 96.8% at the laser wavelength of 1064 nm. A three-dimensional finite element model based on the heat-conduction equation was developed to simulate the distribution of transient temperature filed. By monitoring the temperature variation at the backside center of aluminum alloy substrate during laser irradiation and comparing with the simulation results, it is found that KS-T coating could effectively protect the substrate from laser ablation. The simulation results demonstrated reflectance decrease of samples after a period of irradiation. The possible reasons for the reflectance decrease were proposed. The calculation results also showed that an obvious temperature drop emerged at the coating/substrate interface when interface thermal resistance (ITR) was considered. Eventually heat flux was prevented from flowing to the substrate and aluminum alloy kept a low temperature.

Key words: anti-laser-ablation coating, high reflectance, finite element modeling, interface thermal resistance (ITR)

中图分类号:

TQ174

邹洋, 赵丽丽, 游丽君, 陈笑迎, 宋力昕. 高反射率抗激光烧蚀涂层的制备及数值模拟研究[J]. 无机材料学报, 2016, 31(8): 869-875.

ZOU Yang, ZHAO Li-Li, YOU Li-Jun, CHEN Xiao-Ying, SONG Li-Xin. Preparation and Numerical Simulation Investigation of High Reflectance Anti-laser-ablation Coating[J]. Journal of Inorganic Materials, 2016, 31(8): 869-875.

图/表 9

Fig. 1 The three-dimensional finite simulation model

Fig. 2 Reflectance spectra of KS-T coating with different TiO2 particle sizes

Fig. 3 The 1064-nm reflectance of KS-T coating influenced by pigment volume concentration

Fig. 4 Images of samples irradiated by 1064-nm CW laserUncoated sample (laser switched off at 11 s); (b) Coated 200 µm KS-T coating (laser switched off at 36 s)

Table 1 Temperature-dependent parameters of KS-T coating

T / ℃	25	100	200	300	400	500	600	700
k/(W·m^-1·K^-1)	1.145	0.943	0.883	0.805	0.790	0.746	0.727	0.727
C_p/(J·kg^-1·K^-1)	699	772	844	881	907	937	967	978

Fig. 5 Typical temperature at backside center of the aluminum alloy vs time

Fig. 6 Comparison of the experimental and simulation results(a) Without considering reflectance change; (b) Considering reflectance change

Fig. 7 The simulation results(a) Backside center temperature of the sample coated by KS-T coating; (b) Temperature along the path B; (c) Temperature distribution plot without considering interface thermal resistance; (d) Temperature distribution plot with considering interface thermal resistance. ((b)-(d) are at the ending time of laser irradiation)

Fig. 8 SEM images of surfaces of KS-T coating(a) Before laser irradiation; (b) After laser irradiation

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