HfB2-SiC-HfC陶瓷相组成与相成分定量分析的对比研究

以两种不同WC含量、不同球磨介质的无压烧结HfB₂-SiC-HfC超高温陶瓷为研究对象, 对比了两套集成式相组成和相成分定量分析方法, 发现基于X射线衍射和扫描电镜分析的HfB₂、SiC和HfC相组成和固溶度测量结果相互符合, 都适用于复相陶瓷的综合性定量分析。基于扫描电镜的分析还进一步发现和测量出痕量WB相的含量; XRD-K值法被成功应用于测量固溶度低的相组成。两个对比样品的定量分析结果表明: 烧结助剂含量和球磨介质的改变都不影响W在HfB₂和HfC相中的固溶度, 支持了反应致密过程中液相起关键作用的观点; SiC球磨会造成W的损失, 因此Si₃N₄是更合适的球磨介质。

Comparative Study on Quantitation of Phase Component and Phase Composition of HfB2-SiC-HfC Ceramics

Phase component and phase composition of two pressureless-sintered HfB₂-SiC-HfC ultra-high temperature ceramic samples were quantitatively analyzed. The results obtained by two different methods were compared. The phase component and phase composition for HfB₂, SiC and HfC phases are in consistence, suggesting that the two methods respectively based on X-ray diffraction (XRD) and scanning electron microscope (SEM) are both applicable to the phase quantification for ceramic composites. Trace WB phase was also detected and further quantified by the backscattered electron (BSE) method. XRD-K value method was successfully extended to quantify the low-solution phase components. Quantitative results of stable W solute levels in HfB₂ and HfC phases in both samples, which were prepared with different milling media and WC contents, indicate that the liquid phase plays a key role in the reactive-densification process. The loss of W by the SiC milling makes Si₃N₄ to be more suitable milling medium.