Thermal fatigue resistance is a desirable property for cemented carbides, whose many applications include cutting and drilling tools as well as and other fields where thermal fatigue is a major failure mechanism. When cemented carbides are subjected to chemically aggressive environments, corrosion can play an important role in the degradation of the material. It is apparent that materials in applications should not only resist the thermal fatigue, but also be resistant to damage caused by corrosion. Studies of thermal fatigue, together with erosion of hard metals, are of significance for such materials used in critical components such as valves, dies and cutting and drilling tools.

In this paper, which was originally featured in Elsevier’s Journal of Refractory Metals and Hard Materials, the “notch quench method” was used to study the influence of pH values on thermal fatigue crack propagation behavior of WC–8Co cemented carbide. The pH values of the aqueous solutions were varied between 5.2, 7.4 and 8.8. The results show that the corrosive environment has a strong influence on the thermal fatigue crack propagation behavior of the materials for testing. Acidic and alkali environment can reduce the thermal fatigue crack initial life and increase the crack propagation rate. Thermal attack results in a significant loss of hardness and the effect is even visible in an acidic environment. In all cases, only WO3 and CoWO4 phases are present in the oxides. The mode of crack propagation requires the simultaneous actions of thermal attack and corrosion.

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