The fabrication of three-dimensional silicon nitride (Si₃N₄) fiber-reinforced silicon nitride matrix (3D Si₃N_4f/BN/Si₃N₄) 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 Si₃N_4f/BN/Si₃N₄ 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 Si₃N_4f/BN/Si₃N₄ 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.

通过前驱体渗透和热解（PIP）制备具有氮化硼（BN）界面的三维氮化硅（Si ₃ N ₄）纤维增强氮化硅基体（3D Si ₃ N _4f /BN/Si ₃ N ₄）复合材料) 过程被报告。使用 1000-1200 °C 的热处理来分析 Si ₃ N _4f /BN/Si ₃ N ₄复合材料的热稳定性。发现热处理后的抗弯强度和断裂韧度呈先减小后增大的规律，分别为191±13 MPa和5.8±0.5 MPa·m ^1/2分别对于制造的复合材料，在 1100 °C 下退火的复合材料分别达到最小值 138 ± 6 MPa 和 3.9 ± 0.4 MPa·m ^1/2。热处理对Si ₃ N _4f /BN/Si ₃ N ₄的影响机理复合材料包括：（Ⅰ）进一步陶瓷化导致的基体收缩，导致复合材料中的孔和裂纹等缺陷；（Ⅱ）预应力松弛、热残余应力（TRS）重新分布和更好的纤维/基体润湿（F/M）增加界面结合强度 (IBS) 的表面。因此，热处理通过改变基体和 IBS 的性能来影响复合材料的机械性能，其中纤维上的载荷传递效率随着基体的微观结构演变和 IBS 的逐渐增加而波动。