Abstract:The fractal Brownian model of the secondary electron image of fracture surfaces has been founded and the quantitative analysis method on the three dimensional morphology of surfaces by using digital image processing (DIP) system as a means of information processing proposed. It has been proven theoretically and experimentally that the new quantitative treatment can measure the three dimensional morphology of fracture surfaces exactly and is independent of the linear transformation of the intensity of secondary electron image. The relationships among the fractal dimension of fracture surfaces, transverse rupture strength and microstructure of Ti(C,N) based ceramets have been studied. The microfracture fractal model of tested materials has been founded and the estimated fractal dimension formula of fracture surfaces proposed. The experimental results have shown that the common logarithm values of transverse rupture strength, lg_σbb,increase linearly with the increase of fractal dimension,D_F.The measured fractal dimension depends on the choice of measuring unit. There is an upper critical measuring unit and its value is 0.07μm.

Key words: Ti(C,N) based ceramets　fracture surface　fractal analysis