反应烧结Si3N4陶瓷断裂韧性的实验研究

本文对反应烧结氦化硅 Si_3N_4陶瓷的断裂韧性进行实验研究,用三种不同试件进行了测试,这三种试件是:山形切口双悬臂粱试件,山形切口三点弯曲梁试件和直穿透切口三点弯曲梁试件.用有限元方法分析了直穿透切口三点弯曲梁切口宽度对应力强度因子的影响,结合断裂载荷测定值估算了材料的断裂韧性值,指出直切口无预制裂纹试件的测定值必须用有限元法进行修正才能得到正确结果.

Fracture Toughness of Reaction Sintered Si_3N_4 Ceramics

Fracture toughness of reaction sintered Si_3N_4 was measured by using three types of specimens:two types of chevron-notched specimens and one type of straight- through-notched 3-point bending beam specimens.These specimens were made from two batches of Si_3N_4.The experimental data of K_(IC)were compared with those listed in hand. book of technical and engineering ceramics.Finite element method was used to analyse the effect of the width of notch in the straight-through-notched specimen.In this paper,it is pointed out that in order to obtain accurate K_(IC),the tested results of the straight- through-notched specimen must be modified with FEM.Based upon FEM,the curve of correction factor(K_r)of critical load versus radius of the notch(r)is presented.