Laminated Si3N4-Mo Composites Produced by Hot Pressing

In this paper, the physical, mechanical and friction behavior of Si3N4-Mo laminated composites were investigated. It can be found that the multilayer structure could improve the fracture toughness of laminated composite compared with pure Si3N4. Through the thermodynamic and kinetic calculations of chemical reactions, we conclude that the main product of the interface is Mo5Si3 which caused poor physical and mechanical properties of Si3N4-Mo layered ceramics. The higher content of Mo was beneficial to hinder the diffusion of cracks and improved the fracture toughness of the material, but with the lower content of Mo, Si3N4-Mo laminated ceramic composite had better tribology properity . In addition, with the increase of the load, the tribology properity of Si3N4-Mo laminated ceramic composite decreased, and the friction mechanism of Si3N4-Mo/TC4 is a mixed wear of adhesive wear and abrasive wear.

Destruction Process Analysis of Laminated Ceramic Composites Based on APDL

Laminated composites are the effective ways to toughen Al2O3 ceramics at present. The destruction process analysis of laminated ceramic composite is studied in this paper taking the Al2O3/ZrO2 ceramic composite as the example through the APDL programming. The micro model is established in ANSYS. And the failure stresses of each ply of the ceramic can be calculated by micromechanics method. Then the calculated failure stresses are compared to the simulated failure stresses. The micro model can visualize the destruction process of laminated ceramic composite. The failure criteria of composite material can be self-defining in ANSYS by using APDL. Some ideas of ANSYS application on composite material are given in this paper.

Dynamic Observation of Fracture Process in a Silicon Carbide- Matrix Laminated Ceramic Composite

The dynamic process of crack initiation and propagation in a SiC/BN-Al2O3 laminated composite was observed in situ by scanning electron microscopy. During a bending test with a single-edge notched-beam specimen, an interfacial crack first initiated in the interlayer near the notch tip, after which a through-thickness crack formed in the matrix layer at the notch tip. After the through-thickness crack had grown across the first matrix layer, it was deflected by the next interlayer and again became an interfacial crack. Interfacial cracks and through-thickness cracks were generated alternately until the composite failed. The load-displacement plot of the laminated composite exhibited several peaks, each caused by one propagation of a through-thickness crack. The toughening mechanisms of the laminated composite included crack deflection, interfacial cracking, and through-thickness branch cracking.