基于Beckmann-Kirchhorff简化模型表征钛合金板材表面清洁度

Surface Cleanliness Characterization of Titanium Alloy Sheet Based on Beckmann-Kirchhorff Simplified Model

激光清洗的工业需要对材料表面清洗前后的清洁度评价提出了高要求。提出使用基于表面粗糙度测量的双向反射技术来表征材料表面质量,以自相关长度(T)与表面粗糙度均方根偏差(σ)作为表征样品表面质量的关键参数。基于Beckmann-Kirchhorff散射积分模型,在粗糙表面上进行合理的简化后,研究了入射光强(I0)和反射光强(Is)的比值(Is/I0)与波长平方分之一(1/λ^(2))的关系。在简化模型下,在g值比较大的垂直入射方向上,可以获得比较理想的线性曲线。线性拟合获得的参数σ_(g)可以作为表面清洁度的表征值。在实验中,将一束氙灯白光以垂直的角度照射到钛合金板材TA15样品表面,收集样品表面镜面反射出的光束。实验结果证实了样品表面质量与σ_(g)值大小的相关性。所提方法是无接触式的光谱探测方法,实现了高速扫描,方便快捷,可以在线判断激光清洗后的清洁度。

With the industrial need of laser cleaning,new requirements are put forward for the cleanliness evaluation of material surfaces before and after cleaning.In this paper,the bidirectional reflection technology of surface roughness measurement is proposed to characterize the surface quality of materials,and the autocorrelation length(T)and the root mean square of surface roughness(σ)are taken as the key parameters to characterize the surface quality of samples.Based on the BeckmannKirchhorff integral scattering model and after a reasonable simplification on rough surfaces,we plot the ratio Is/I_(0) of the incident light intensity(I_(0))to the reflected light intensity(Is)versus the inverse square of wavelength(1/λ^(2)).Under the simplified model,an ideal linear curve can be obtained in the vertical incident direction with a large g value.The parameterσ_(g) obtained by linear fitting can be used as the characterization value of surface cleanliness.In the experiment,a beam of white light(xenon lamp)is first used to irradiate the surface of the titanium alloy sheet TA15 sample at a vertical angle,and then the specular reflected light beam on the surface of the sample is collected.The experimental results confirm the correlation between the surface quality of the sample and theσ_(g) value.This method is a noncontact spectral detection method,which can realize highspeed scanning,is convenient and fast,and can be used to online judge the cleanliness after laser cleaning in practical work.