Hot pressing sintering process and sintering mechanism of W-La2O3-Y2O3-ZrO2

The W-La2O3-Y2O3-ZrO2 materials were prepared by vacuum hot pressing sintering process. The microstructure was characterized by scanning electron microscopy (SEM). The effects of sintering temperature, sintering pressure, holding time and heating rate on relative density, hardness and microstructure were studied. The sintering activation energy of the powder was calculated. Based on the result, the best sintering parameters by vacuum hot pressing sintering are as follows: sintering temperature of 1600 degrees C, sintering pressure of 60 MPa and holding time of 60 min. The heating rate is 10 degrees C center dot min(-1) from room temperature to 1000 degrees C and 4 degrees C.min(-1) from 1000 to 1600 degrees C. Using this process, the grain size is about 3 mu m in diameter with relative density at 99.7%, and the hardness is HV 528.5. The sintering characteristic index (n) of the specimen is 4, and the sintering mechanism mainly depends on the diffusion from the surface to the intragranular in the volume diffusion. The sintering activation energy of W-La2O3-Y2O3-ZrO2 material is 286.2 kJ.mol(-1), which indicates that the powder has higher activity in sintering process. Graphic abstract