Crack propagation and residual stress in laminated Si_3N_4/BN composite structures

摘要

The level of residual stress and crack propagation in a new generation of laminates, based on silicon nitride (Si_3N_4) layer and a mixture of boron nitride (BN) and alumina (Al_2O_3) interlayer, was presented. The structure consists of alternated concentric rings of S13N4 separated by the weak BN interlayer possessing no planes of easy crack propagation and fracture resistance much larger than that of any classical planar laminates. The results on direction of crack propagation and residual stress in relation to inter-layer composition, the number of layers, and their thickness are investigated and reported. The effect of residual stress on crack propagation was studied by using Vicksrs intentation.