Papers by Author: Tao Zhang

Abstract: The AlN/Ti laminated composites were fabrication by plasma activated sintering. In the composites, the AlN layers were matrix layers and the Ti layers were as the toughening layers. The microstructure and mechanical properties were studied. XRD and SEM results showed that a new phase (TiN, Al5Ti2) in the layer interface was generated by reaction of AlN and Ti. The AlN/Ti interface bonding was strengthened by existing of the new phase, plastic deformation and bridging of ductile Ti phase. The crack propagation path would be extended by the flexuous pattern. Therefore, the fracture toughness of composites was improved obviously comparing with the monolithic AlN and the bending strength decreased a little.

Abstract: The relationship between the processing technology and the dielectric property of the laminated AlN/h-BN ceramic composites has been studied. The results showed that the main polarization mechanism of laminated ceramic composites in low frequency range is space charge polarization at the interface of AlN layer and BN layer. Due to the affection of porosity, the permittivity increases and the dielectric loss decreases with increasing the hot pressing temperature. The permittivity increases and the dielectric loss decreases with increasing thickness ratio of different layer., Both permittivity and dielectric loss increase with increasing the content of AlN doping in BN layer.

Abstract: AlN/BN laminated ceramic composites were fabricated using tape-casting and hot-pressing by optimizing the designs of the structure and geometry of AlN/BN laminated ceramic composites. The results showed that the fracture toughness and bending strength for AlN/BN laminated ceramics reached 9.1MPa.m1/2 and 378MPa respectively. The fracture toughness is two times higher than that of AlN monolithic ceramics. The excellent fracture toughness of AlN/BN laminated ceramics could be mainly attributed to crack deflection, delaminating, branching, parallel propagation and crack laminate pilling out at the AlN/BN weak interface.