Wang Bokang, Bai Tanglong, Wang Weide, Zhang Hongti
Shanghai Key Laboratory of High-Resolution Electron Microscopy, School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.
Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China.
Materials (Basel). 2024 Sep 16;17(18):4549. doi: 10.3390/ma17184549.
Silicon nitride (SiN) is widely used in structural ceramics and advanced manufacturing due to its excellent mechanical properties and high-temperature stability. These applications always involve deformation under mechanical loads, necessitating a thorough understanding of their mechanical behavior and performance under load. However, the mechanical properties of SiN, particularly at the micro- and nanoscale, are not well understood. This study systematically investigated the mechanical properties of bulk SiN and SiN whiskers using in situ SEM indentation and uniaxial tensile strategies. First, nanoindentation tests on bulk SiN at different contact depths ranging from 125 to 450 nm showed significant indentation size effect on modulus and hardness, presumably attributed to the strain gradient plasticity theory. Subsequently, in situ uniaxial tensile tests were performed on SiN whiskers synthesized with two different sintering aids, MgSiN and YO. The results indicated that whiskers sintered with YO exhibited higher modulus and strength compared to those sintered with MgSiN. This work provides a deeper understanding of the mechanical behavior of SiN at the micro- and nanoscale and offers guidance for the design of high-performance SiN ceramic whiskers.
氮化硅（SiN）因其优异的机械性能和高温稳定性而广泛应用于结构陶瓷和先进制造领域。这些应用总是涉及机械载荷下的变形，因此有必要深入了解其在载荷下的力学行为和性能。然而，氮化硅的力学性能，特别是在微观和纳米尺度上，尚未得到充分了解。本研究采用原位扫描电子显微镜压痕和单轴拉伸策略，系统地研究了块状SiN和SiN晶须的力学性能。首先，对块状SiN在125至450nm不同接触深度下进行纳米压痕试验，结果表明模量和硬度存在显著的压痕尺寸效应，这可能归因于应变梯度塑性理论。随后，对用两种不同烧结助剂MgSiN和YO合成的SiN晶须进行了原位单轴拉伸试验。结果表明，与用MgSiN烧结的晶须相比，用YO烧结的晶须具有更高的模量和强度。这项工作为深入了解SiN在微观和纳米尺度上的力学行为提供了依据，并为高性能SiN陶瓷晶须的设计提供了指导。
