n-Al_2O_3/Ni-Co纳米复合电刷镀层表面形貌的分形维数研究

Study on surface morphology of electro-brush plated n-Al_2O_3/Ni-Co composite coating by fractal dimension methods

采用电刷镀技术,在45钢上获得了n-Al2O3/Ni–Co纳米复合电刷镀层。研究了镀液中纳米颗粒加入量对镀层的表面形貌和显微硬度的影响,并利用盒维数的计算方法,计算了表面形貌的分形维数,初步建立了表面形貌的分形维数与镀层显微硬度之间的关系。对比分析表明:随着镀液中纳米颗粒含量的增加,镀层表面形貌的分形维数先减小后增大,镀层的显微硬度则先增大后减小,但都在镀液中纳米颗粒加入量为20g/L时达到最值,即镀层表面形貌的分形维数与其显微硬度有负相关的对应关系。

n-Al2O3/Ni-Co nanocomposite coatings were prepared on 45 steel by electro-brush plating. The effects of n-Al2O3 content in plating bath on the surface morphology and microhardness of composite coating were studied. The fractal dimension values of surface morphologies were calculated by box-counting method. The relationship between microhardness and fractal dimension of the surface topography of n-Al203/Ni-Co coating was established. The results of comparative analysis showed that the fractal dimension is decreased initially and then increased with the increasing of n-Al2O3 content in plating bath, but the microhardness is increased initially and then decreased. The fractal dimension reached minimum and the microhardness reached maximum when the content of n-Al2O3 was20 g/L in plating bath. There is a negative correlation between the fractal dimension of surface morphology of n-Al2O3/Ni-Co composite coating and its microhardness.