Effects of Layer Thickness on Microstructure and Mechanical Properties of TiCN-VC/TiCN-TaC Layered Ceramics

Using vacuum hot pressing sintering technology and powder stacking technology, four kinds of TiC_0.7N_0.3-VC/TiC_0.7N_0.3-TaC layered ceramics with different layer thicknesses were prepared at 1450 ℃.The effects of layer thickness on the microstructure and mechanical properties were investigated.The results show that the TiC_0.7N_0.3-VC layer is mainly composed of TiCN, (Ti, V, Mo)(C, N) solid solution, and a small amount of MoNi₄, and the TiC_0.7N_0.3-TaC layer is mainly composed of TiCN, (Ti, Ta, Mo)(C, N) solid solution and a small amount of MoNi₄. As the layer thickness increases, their microstructures are basically unchanged, and the average grain size is about 2 μm.As the layer thickness increases from 0.20 mm to 0.32 mm, the relative density and Vickers hardness first increase and then decrease, the variation of flexural strength is smaller, and the interlaminar fracture toughness gradually decreases, while the fracture toughness of layer surfaces is basically unchanged.When the layer thickness is 0.28 mm, the ceramic has higher density, uniform grain size, and obtain excellent mechanical properties. Its Vickers hardness is 20.9 GPa, its flexural strength is 925.0 MPa, and its interlaminar fracture toughness is 7.7 MPa·m^1/2.