SiC-BN层状陶瓷复合材料叠层方式优化设计

The laminated ceramic composites can effectively improve the toughness of pure ceramic material, which is widely concerned by researchers. In the material design stage, the mechanical properties of laminated ceramics can be improved significantly by optimizing the lamination method. However, there is a lack of optimal design method for lamination in previous researches. In this study, genetic algorithm based on laminated beam model was used to optimize the ratio of layer thickness. Three laminated forms of SiC-BN laminated ceramic composites: 5: 1, 10: 1 and gradient body were prepared by tap-casting-lamination forming combined with pressureless sintering method. Three-point bending tests of intact specimens and notched specimens were carried out. The toughening mechanism was analyzed based on macro damage analysis. The experimental results show that the bending strength of the gradient laminated ceramic optimized by analytical method is up to 434.5 MPa. Compared with the fixed laminated thickness, the mechanical properties of the laminate are improved greatly, and the defect insensitivity has been maintained. Further analysis shows that more soft layers distributed in the tension part and thicker hard laminates distributed in the compression part are the important reasons for the better performance of the gradient structure.