【摘要】 通过压痕小裂纹直接量测法获得Si3N4-TiN/BN层状复合材料的阻力曲线 ,并采用指数经验公式拟合处理了实验数据 ,解释了各拟合参数的物理意义 .对层状复合材料阻力曲线所具有的独特的台阶状进行了分析 ,并对层状复合材料具有高韧性的机理作了深入的研究 .结果表明弱间层的层状结构具有明显的增韧效果 .这是由于弱间层的存在将出现裂纹偏转现象 ,吸收大量的断裂功 ,从而大幅度提高了裂纹的扩展容限 ,使断裂韧性有较大增长 .更多还原

【Abstract】 R-curves for Si 3N 4-TiN/BN laminated composites are established by direct measurement of the propagations of Vickers indentation cracks in length under progressively applied bending stresses. An empirical exponential relation is fitted for the data. The unique“step” shape that the R-curve of laminated composites possesses is discussed. Moreover, the mechanism of high fracture toughness and prolonged crack tolerance shown in R-curve deduction of laminated composites is further explained. The results indicated that the laminated structure with the weak layer possess toughening results obviously. The crack will deflect because the weak layer exits, which will absorb more amounts of fracture work and improve the crack tolerance greatly, therefore the fracture toughness increases remarkably.更多还原