Microstructure-flexural strength correlation and efficacy of rare earth nitrates on the sintering of SiCf/SiC composites
Microstructure-flexural strength correlation and efficacy of rare earth nitrates on the sintering of SiCf/SiC composites
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DOI：
10.1016/j.jeurceramsoc.2015.11.040
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发表时间：
2016-03
影响因子：
5.7
通讯作者：
Pipit Fitriani;Amit Sharma;D. Yoon
中科院分区：
文献类型：
--
作者：
Pipit Fitriani;Amit Sharma;D. Yoon
真空渗透技术用于渗透SiC基基体相，含有稀土（Sc，Er和Yb）硝酸盐（10重量%），作为烧结添加剂，加入到涂有热解碳（PyC）的2D编织Tyranno SiC织物预成型件中，用于制造致密的SiCf/SiC复合材料。通过插入SiC绿色带，在1750 °C、20 MPa的压力下热压2 h，复合材料的致密度>95%。研究了各种稀土硝酸盐的添加对SiCf/SiC复合材料的密度、显微结构和力学性能的影响。特别是，Sc-硝酸盐被认为是最有效的烧结添加剂在保留超细晶粒尺寸分布和保留结构完整性，通过保留弱PyC接口。最后，在确定的主要失效机制的基础上，提出了微观结构与抗弯强度变化之间的相关性。
A vacuum infiltration technique was used to infiltrate a SiC-based matrix phase, containing rare earth (Sc, Er and Yb) nitrate (10 wt.%) as a sintering additive, into a 2D-woven Tyranno SiC fabric preform coated with pyrolytic carbon (PyC) for the fabrication of a dense SiCf/SiC composite. By inserting a SiC green tape, a high composite density >95% was achieved after hot pressing at 1750 °C for 2 h under a pressure of 20 MPa. The effects of the addition of each rare earth nitrate on the density, microstructure and mechanical properties of the SiCf/SiC composites were investigated. In particular, Sc-nitrate was found to be the most effective sintering additive in terms of retaining an ultrafine grain size distribution and the retention of structural integrity by preserving the weak PyC interface. Finally on the basis of identified key failure mechanisms, a correlation between microstructure and variation of flexural strength was proposed.