Effects of carbothermal prereduction temperature and Co content on mechanical properties of WC-Co cemented carbides

WC-Co cemented carbides were prepared via an in situ synthesis method, including the carbothermal prereduction of WO3 and Co2O3 to remove all oxygen and a subsequent carbonization-vacuum sintering process. The experimental results revealed that as the prereduction temperature increased from 1000 to 1200 degrees C, the grain sizes of WC in WC-6Co and WC-12Co cemented carbides increased from .91 to 1.09 and .97 to 1.19 mu m, respectively. Further, the fracture toughness of the sintered WC-6Co and WC-12Co cemented carbides increased from 9.97 to 10.83 and 11.11 to 18.30 MPa m(1/2), respectively. In contrast, the hardness of the WC-6Co and WC-12Co cemented carbides decreased from 1477 to 1368 and 1351 to 1184 HV30, respectively. For a given prereduction temperature, an increase in Co content can improve the fracture toughness while lowering the hardness. In addition, an increase in the prereduction temperature or Co content led to an increase in the grain size of WC, which resulted in a transgranular fracture as the dominant mode.

Automated summary

WC-Co cemented carbides were synthesized in situ through carbothermal prereduction of WO3 and Co2O3 followed by carbonization-vacuum sintering. Higher prereduction temperature led to larger grain sizes and higher fracture toughness, but lower hardness for both WC-6Co and WC-12Co cemented carbides. Increasing Co content also improved fracture toughness while reducing hardness. Additionally, higher prereduction temperature or Co content resulted in larger WC grain sizes and transgranular fracture as the dominant mode.