Quantitative fractography of sintered carbides
Abstract
Three grades of sintered carbides ("Baildonit" Co Ltd) with diversified tungsten carbide size (0.5-8.0 µm) and cobalt binder (6-9.5 wt. %) were investigated. The specimens were fractured using three points bending device mounted in scanning electron microscope. Values of bending strength and deflection measured this way were used in further fractography analysis. The fractures exhibited gradual change of certain features (from the coarse to fine grained specimens): decrease in transcrystalline fracture fraction, decrease in secondary cracks and WC particles cracks frequency. Confocal laser microscopy (TSC 4D Leica Laser Technik) was used to obtain 3D topography of the fractures and main fractography parameters - average arithmetic profile deviation from the average line (Ra), surface roughness (Rs) and fractal dimension.