Effects of heat treatment on mechanical properties of 3D Si3N4f/BN/Si3N4 composites by PIP. Issue 14 (November 2021)

• Record Type: Journal Article
• Authors: Zhou, Jie; Ye, Fang; Cheng, Laifei; Li, Mingxing; Cui, Xuefeng; Fu, Zhiqiang; Zhang, Litong; Chai, Nan
• Is Part Of: Journal of the European Ceramic Society. Volume 41:Issue 14(2021)
• Page Start: 6905
• Page End: 6914
• Publication Date: 2021-11
• Subjects: Si3N4f/BN/Si3N4 composites -- Microstructural evolution -- Mechanical properties -- Heat treatment -- Precursor infiltration and pyrolysis; Ceramic materials -- Periodicals; Composite materials -- Periodicals; Matériaux céramiques -- Périodiques; Composites -- Périodiques; Ceramic materials; Composite materials; Periodicals; Electronic journals; 666.05
• DOI: 10.1016/j.jeurceramsoc.2021.07.043
• Languages: English
• ISSNs: 0955-2219

Abstract

Abstract: The fabrication of three-dimensional silicon nitride (Si3 N4 ) fiber-reinforced silicon nitride matrix (3D Si3 N4f /BN/Si3 N4 ) composites with a boron nitride (BN) interphase through precursor infiltration and pyrolysis (PIP) process was reported. Heat treatment at 1000–1200 °C was used to analyze the thermal stability of the Si3 N4f /BN/Si3 N4 composites. It was found after heat treatment the flexural strength and fracture toughness change with a pattern that decrease first and then increase, which are 191 ± 13 MPa and 5.8 ± 0.5 MPa·m 1/2 respectively for as-fabricated composites, and reach the minimum values of 138 ± 6 MPa and 3.9 ± 0.4 MPa·m 1/2 respectively for composites annealed at 1100 °C. The influence mechanisms of the heat treatment on the Si3 N4f /BN/Si3 N4 composites include: (Ⅰ) matrix shrinkage by further ceramization that causes defects such as pores and cracks in composites, and (Ⅱ) prestress relaxation, thermal residual stress (TRS) redistribution and a better wetting at the fiber/matrix (F/M) surface that increase the interfacial bonding strength (IBS). Thus, heat treatment affects the mechanical properties of composites by changing the properties of the matrix and IBS, where the load transfer efficiency onto the fibers is fluctuating by the microstructural evolution of matrix and gradually increasing IBS.