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.

Two types of cemented carbides have been elaborated from three mixtures of WC and Co powders containing 3, 5 and 6% of cobalt mass. Three samples of these mixtures have been obtained by liquid phase sintering and three others of the same composition have been sintered then densified by hot isostatic pressing (HIP). Observations by scanning electronic microscope have allowed to note that the samples elaborated by sintering followed by an HIP densification have a more homogeneous structure than that observed in the sintered samples. Under the compression, the WC grains flattens and interlock more easily from one another which gives a uniform surface appearance. Energy dispersion analysis shows that these samples contain a very small voluminal fraction of graphite and residual porosities, these are more pronounced in sintered samples, especially in the case of alloys with a low Co content (3 and 5%). X rays diffraction analysis allowed to show clearly the existence of cobalt type carbide in the sintered samples. Measurement of the closed porosity allows to observe that the sintering process followed by densification by HIP leads to the elaboration of alloys with a low rate of closed porosity. Microhardness of these samples have improved hardnesses.