片状粉末表面特征的表征方法

Analysis on surface topography parameters of flaky powder

对不同片状粉末的显微照片进行了分析,选择四个机械表面粗糙度参数:Ra,Rq,Sk和K对不同粉体颗粒的图像进行表面几何特征的描述,根据片状粉末图像的灰度值计算相应的粗糙度数值。并提出用分形的方法进行进一步表面分析,采用DBC算法计算分形盒子维,作为颗粒表面的分形维数。结果表明,计算得到的粗糙度参数中,Ra,Rq的变化趋势与人为观察结果不符。Sk和K的数值与主观观察结果较为吻合,但是对珠光效应比较敏感。表面分形维数的数值最为稳定,且符合观察结果,与主观视觉效果一致,在一定程度上,可有效地反映粉体表面的粗糙程度。从而为片状粉体的制备和应用研究,提供一个较为合理的表面几何特征的表征方法。

In this paper, digital images of flaky powder are used to analyse the surface topography. Based on the grey scale of each image, four roughness parameters are applied to describe the roughness of the powder surface, as well as the surface fractal dimension. Images of flaky powders are arranged in order of ruggedness based on subjective observations. It was found that parameter Ra and Rq can hardly meet the subjective observations. While Sk and K follow the sequence almost. However, the pearlescent effect of some powders has much influence on the value of Sk and K that may cause wrong measurement with these kinds of powders. The surface fractal dimension is shown to be a most successful method for the description of surface topographies. Its measurement coincides with people's subjective feeling. It is valuable to apply the surface fractal dimension to the preparation and application of flaky powder as an efficient expression of the surface roughness.