Comparative Study By Image Analysis Of Wc-Co Alloys Elaborated By Liquid Phase Sintering And Hot Isostatic Pressing

Hot isostatic pressing (HIP) is known to be a process which permits to elaborate totally dense cemented carbide with perfect homogenous structure. It also offers the possibility to totally consolidate the powders mixtures WC-Co without reaching the fusion temperature of the binding cobalt. The HIP process was used in this work to produce a cemented carbide with an 8,11 and 20% cobalt mass. Their properties are thus compared with those of similar samples elaborate by liquid phase sintering. The microstructural characterization of both types of samples is described from observation by scanning electron. The qualitative analysis of the sample is realized by X-ray diffraction and energy dispersion. The use of image analysis techniques allowed us to access the morphological parameters of the binding phase in both types of elaborate sample. The spectra obtained by X-ray diffraction show, the absence of the phase (Co3W3C, Co6W6C) for the sample elaborated by hot isostatic pressing (HIP) method, unlike sintering in the liquid phase where it is clearly highlighted. The SEM observations clearly show the absence of residual carbon inclusions for the HIP method as well as the best distribution of the phases highlighted by the images obtained by mapping. In conclusion, the results obtained give us a clear idea on improving densification, increasing hardness and decreasing porosity for the HIP hot isostatic pressing method.