SiC-BN层状陶瓷复合材料叠层方式优化设计

层状陶瓷复合材料可有效提高纯陶瓷材料的韧性，受到研究者的广泛关注。在材料设计阶段，通过优化叠层方式可显著提高层状陶瓷的力学性能。然而，在现有研究中缺乏叠层方式的优化设计方法。本研究采用基于复合梁模型的遗传算法得到了最优层厚比；针对SiC-BN层状陶瓷复合材料5∶ 1、10∶ 1和梯度体三种铺层形式采用流延成型结合无压烧结法进行材料制备，并进行了完好试件和含缺口试件的三点弯曲试验；基于宏观损伤分析对其增韧机制进行了分析。试验结果表明:通过解析方法计算得到的最优梯度体层状陶瓷的弯曲强度达到434.5 MPa。其力学性能相比于固定层厚比铺层方式有较大提高，同时还保持了较高的缺陷不敏感特性。进一步分析表明:受拉部分分布的较多软层和受压部分分布的较厚硬层是梯度体结构较好性能的重要原因。 

Optimum design of SiC-BN laminated ceramic composites

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.