基于数字图像处理的等离子喷涂NiCr-Cr_3C_2涂层纳米压痕有限元模拟

Simulation of Nanoindentation Tests of Plasma Sprayed NiCr-Cr_3C_2 Coatings Based on Digital Image Processing

以等离子喷涂NiCr-Cr3C2涂层为研究对象,应用数字图像处理技术提取涂层孔隙分布形态,生成了包含孔隙在内的涂层有限元模型,并模拟计算了涂层纳米压痕压入过程。通过阈值迭代法、小波变换法和边界图形几何矢量化,提取了涂层真实细观结构的几何矢量图,并根据该结构图计算涂层孔隙率为6.88%。以提取的涂层矢量结构图为有限元模型基础,模拟纳米压痕试验加载过程,其载荷-位移曲线与试验曲线匹配性较好,表明该方法可将涂层微观结构和宏观力学性能结合起来。

Digital image processing （DIP） technology was used to extract meso-structure of plasma sprayed NiCr-Cr3C2 coating and a finite element model including random distribution pores was then built to simulate the nanoindentation test. Image segmentation was processed using grayscale threshold. After that, the edges of pores approximate to the original micrograph were obtained by wavelet transform. Based on this diagram, the calculated porosity was 6. 88~. Finally, through geometry vectorization algorithm, the finite element mesh was generated to model the nanoindentation process in consideration of pores. The modeling load-depth curve agrees with with the experimental curve, which indicates the combination of DIP and simulation can be used to link microstructure with macro-mechanical properties.