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ZrB 2 /SiC, ZrB 2 /SiC/Si 3 N 4 and ZrB 2 /SiC/WC ceramic tool materials were prepared by spark plasma sintering technology, and their oxidation resistance was tested at different oxidation temperatures. When the oxidation temperature is 1300 °C, the oxide layer thickness, oxidation weight gain and flexural strength of ZrB 2 /SiC/Si 3 N 4 ceramic tool material after oxidation are 8.476 μm, 1.436 mg cm−2 and 891.0 MPa, respectively. Compared with ZrB 2 /SiC ceramic tool materials, the oxide layer thickness and oxidation weight gain are reduced by 8.2% and 11.8%, respectively, and the flexural strength after oxidation is increased by 116.1%. However, the addition of WC significantly reduces the oxidation resistance of the ceramic tool material. A dense oxide film is formed on the surface of ZrB 2 /SiC/Si 3 N 4 ceramic tool material during oxidation, which effectively prevents oxygen from entering the inside of the material, thereby improving the oxidation resistance of the ceramic tool material. [ABSTRACT FROM AUTHOR]

ZrB 2 /SiC ceramic granules with uniform a size and spherical shape were prepared by spray drying technology. ZrB 2 /SiC ceramic granules were added into ceramic matrix, and ZrB 2 /SiC/Si 3 N 4 ceramic tool materials with double composite architectures were prepared by spark plasma sintering technology. The mechanical properties from room temperature to 1100°C were measured. The hardness, flexural strength and fracture toughness at room temperature are 18.0 GPa, 589.0 MPa and 5.93 MPa m1/2, respectively. While the fracture toughness at 1100°C reach 6.1 MPa m1/2 increase by 74.3% compared with the ceramic tool material without double composite architectures. At high temperature, the improvement of fracture toughness is due to the addition of ZrB 2 /SiC ceramic granules that deflect the cracks and propagates along the boundary between the granules and the matrix, which greatly increase the path during the crack propagation process, thereby improving the fracture toughness of the ceramic tool material. [ABSTRACT FROM AUTHOR]

ZrB 2 /SiC/WC ceramic tool materials with a WC content of up to 10 vol% were prepared using spark plasma sintering technology. The mechanical properties at room temperature showed that the ZrB 2 /SiC/WC ceramic tool material with a WC content of 5 vol% had the best comprehensive mechanical properties, with a hardness, flexural strength, and fracture toughness of 19.1 GPa, 590 MPa, and 4.9 MPa·m1/2, respectively. With the increase in temperature, the hardness and fracture toughness of the ZrB 2 /SiC/WC ceramic tool materials gradually decreased; however, the flexural strength first increased and then decreased. When the temperature was 600 °C, the flexural strength reached a maximum value of 630 GPa, which was an increase of 6.8% when compared to that at room temperature. The increase in flexural strength was mainly due to the increase in the transgranular fracturing during the fracture process of the ZrB 2 /SiC/WC ceramic tool material. Dry machining tests of 40Cr hardened steel were performed using ZrB 2 /SiC/WC ceramic tools. As the cutting speed increased, the tool life gradually decreased, but the surface quality of the workpiece gradually increased. When the cutting speed was 300 m/min, the tool life of the ZrB 2 /SiC/WC ceramic tool was 15.8 min, and the surface roughness Ra of the workpiece after cutting was between 1.0 and 2.0 μm. According to the wear morphology, adhesive wear was the main form of the ZrB 2 /SiC/WC ceramic tools. • ZrB 2 /SiC/WC ceramic tool materials were prepared by spark plasma sintering technology. • The change trend of the mechanical properties of ceramic tool materials from RT to 1100 °C was studied. • The mechanism of flexural strength change of ZrB 2 /SiC/WC ceramic tool materials at high temperature was studied. • The machining performance of ZrB 2 /SiC/WC ceramic tools at different cutting speeds was analyzed. [ABSTRACT FROM AUTHOR]