Effects of Layer Thickness on Microstructure and Mechanical Properties of TiC-HfN/TiC-HfC Laminated Ceramics
TiC-HfN/TiC-HfC layered ceramics with different layer thicknesses,consisting of the TiC matrix phase,the HfN and HfC additives and the Ni and Co metal phases,were laminated by the micro-laminated device and then they were sintered at 1500℃by vacuum hot-pressing sintering technology.Their layer thicknesses were 0.25 mm,0.30 mm,0.35 mm and 0.40 mm,respectively.The effects of layer thickness on their microstructure and mechanical properties were investigated.The results show that their fracture morphologies are basically similar to each other,and their grain size is about 5 μm.With the increase of the layer thickness,their relative density,hardness and flexural strength increase first and then decrease,the fracture toughness of their layer basically remains unchanged,and the fracture toughness of their interlayer decreases gradually.When the layer thickness is 0.30 mm,the ceramic has relatively good comprehensive mechanical properties:its hardness is(19.6±0.24)GPa,its flexural strength is(841.1±20)MPa,its layer fracture toughness is(6.5±0.18)MPa·m1/2 and its interlayer fracture toughness is(8.3±0.27)MPa·m1/2.
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