Multifractal characteristic of surface topography of the coatings on cemented carbides

The paper presents investigation results obtained from the AFM microscope of the sintered tool materials uncoated and coated with the TiN and TiN+mono or multi(Ti,Al,Si)N+TiN coatings deposited in the PVD process. Values of the surface fractal dimension and the multifractal spectra were determined using the projective covering method. This value is independent from the scanning range, except for the TiN+mono or multi(Ti,Al,Si)N+TiN coating, which confirms their fractal nature. Variability of the fractal dimension value depending on scale for the TiN+mono or multi(Ti,AI,Si)N+TiN may be caused the presence of clear, yet very fine unevenness and/or inhomogeneity of the coating, which is suggested by analysis of parameter R value. The fractal dimension has a relatively clear interpretation - it is a measure of irregularity and degree of complexity of the surface shape, whereas interpretation of the multifractal spectrum is not unequivocal. Investigation or relationship between parameters describing the multifractal spectrum and physical properties of the examined materials calls for further analyses.