基于Si_(3)N_(4)@MgSiN_(2)核壳结构粉体制备β-Si_(3)N_(4)晶须  

β-Si_(3)N_(4) whiskers preparation from Si_(3)N_(4)@MgSiN_(2) core-shell structure powders

作　　者：王为得 刘一铭 潘勇 莫勇 王伟明 马青松[2] WANG Weide;LIU Yiming;PAN Yong;MO Yong;WANG Weiming;MA Qingsong(College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,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;Science and Technology on Space Physics Labrotary,China Academy of Launch Vehicle Technology,Beijing 100076,China)

机构地区：[1]国防科技大学前沿交叉学科学院,长沙410073 [2]国防科技大学空天科学学院新型陶瓷纤维及其复合材料重点实验室,长沙410073 [3]中国运载火箭技术研究院空间物理重点实验室,北京100076

出　　处：《粉末冶金材料科学与工程》2025年第1期1-10,共10页Materials Science and Engineering of Powder Metallurgy

基　　金：国家自然科学基金资助项目(52202077);国防科技重点实验室基金资助项目(6142907220303);国防科技基础加强计划资助项目(2022-JCJQ-LB-073);湖南省自然科学基金资助项目(2024JJ5407)。

摘　　要：一维单晶β-Si_(3)N_(4)晶须兼具优异的热学、力学、耐高温、耐腐蚀等性能,广泛用作树脂基、金属基及陶瓷基的增强体材料。以氧化物为烧结助剂制备的β-Si_(3)N_(4)晶须存在残留杂质多、长径比低等不足,限制了其增强效果。本研究借助熔盐法在较低温度下制备壳层厚度可控的Si_(3)N_(4)@Mg Si N2核壳结构粉体,再以此粉体为原料烧结制备β-Si_(3)N_(4)晶须,采用X射线衍射仪、能谱仪和扫描电子显微镜研究粉体和晶须的物相组成和微观形貌。结果表明:在高温下,α-Si_(3)N_(4)在壳层Mg Si N2形成的液相中通过“溶解析出”机制实现相转变和Ostwald熟化,形成了高长径比的β-Si_(3)N_(4)晶须。升高烧结温度及提高原料中Mg/Si_(3)N_(4)质量比均可增强液相中的扩散传质,有利于晶须沿[001]方向生长,表现为晶须的长度和长径比增大。同时,Mg Si N2在高温下不稳定的特性促使其分解为Mg、N2及Si_(3)N_(4),保证了晶须的高纯度。因此,在1750℃烧结1 h可制备高纯度、高长径比、易分散的β-Si_(3)N_(4)晶须。本研究提出的晶须新型制备策略经济可行,为高性能β-Si_(3)N_(4)晶须的制备提供了新途径。One dimensional single crystalβ-Si_(3)N_(4) whiskers possess excellent thermal,mechanical,high-temperature and corrosion resistance properties,and are widely used as resin based,metal based,and ceramic based reinforcement materials.β-Si_(3)N_(4) whiskers prepared with oxides as sintering aids have shortcomings such as high residual impurities and low aspect ratio,which limit their reinforcement effect.This study utilized the molten salt synthesis to prepare Si_(3)N_(4)@MgSiN_(2) core-shell structured powders with controllable shell thickness at lower temperature,and further preparedβ-Si_(3)N_(4) whiskers from this powder through sintering.The phase composition and microstructure of powders and whiskers were studied using X-ray diffractometer,energy dispersive spectrometer,and scanning electron microscope.The results show that at high temperatures,α-Si_(3)N_(4) undergoes a phase transformation and Ostwald ripening in the liquid phase formed by the shell MgSiN_(2) through a“dissolution-precipitation”mechanism,resulting in the formation ofβ-Si_(3)N_(4) whiskers with high aspect ratio.Raising the sintering temperature and increasing the Mg/Si_(3)N_(4) mass ratio in the raw material can enhance the diffusion mass transfer in the liquid phase,which is beneficial for the growth of whiskers along the[001]direction,manifest as an increase in whisker length and aspect ratio.At the same time,the unstable nature of MgSiN_(2) at high temperature promotes its decomposition into Mg,N2,and Si_(3)N_(4),ensuring the high purity of the whiskers.Therefore,high-purity,high aspect ratio,and easily dispersibleβ-Si_(3)N_(4) whiskers are prepared by sintering at 1750℃for 1 h.The new preparation strategy of whiskers proposed in this study is economically feasible and provides a new approach for the preparation of high-performanceβ-Si_(3)N_(4) whiskers.

关 键 词：Si_(3)N_(4)晶须 熔盐法 烧结助剂 核壳结构 生长机制 

分 类 号：TQ174[化学工程—陶瓷工业]