X-ray Photoelectron Spectroscopy (XPS) Study of Fracture Mechanism in Sintered Si3N4

The concentration of sintering aids, Y2O3 and Al2O3, appearing on the fracture surface of sintered Si3N4 on which either dynamic or cyclic stress is applied, was determined by X-ray Photoelectron Spectroscopy (XPS). The concentration ratio, (Y+Al)/Si, can be used as a correlational index that is useful to study the fracture behavior. According to our results, there is a direct correlation between larger (Y+Al)/Si concentration ratios on the fracture surface and the tendency of sintered Si3N4 to suffer fracture by cyclic fatigue, namely, intercrystalline cracking is dominant when fracture by cyclic fatigue occurs.