Three SiBCN monoliths: carbon-lean, -moderate and -rich monoliths with the same Si/B/N mole ratio have been prepared by mechanical alloying followed by reactive hot pressing. The role of carbon on phase composition, microstructural evolution and mechanical properties were investigated. XRD and TEM investigations showed that the as-sintered monoliths contain several components: Si metal, SiC, t-BN and BN(C), strongly correlated with the carbon content. TEM results also revealed that BN(C) enwraps SiC grain forming capsule-like structure. Raman, NMR and HRTEM studies suggested that the structural evolution within the BN(C) areas includes the graphitization of amorphous carbon and the lateral growth of BN(C), accompanied by an increase in the defect concentration. The defects form within BN (0002) basal planes resulting from the disordered carbon imbedded, which in turn determines the morphological evolution of BN(C). The ill-developed microstructures for carbon-lean monoliths and the excessive carbon in carbon-rich ones both deteriorate their mechanical properties and densities. This article is protected by copyright. All rights reserved.

中文翻译：

---

SiBCN 整料的碳含量依赖相组成、微观结构演变和机械性能

通过机械合金化和反应热压制备了三种 SiBCN 整料：具有相同 Si/B/N 摩尔比的贫碳、中度和富碳整料。研究了碳对相组成、微观结构演变和机械性能的作用。XRD 和 TEM 研究表明，烧结后的整料包含多种成分：Si 金属、SiC、t-BN 和 BN(C)，与碳含量密切相关。TEM 结果还显示 BN(C) 包裹 SiC 晶粒形成胶囊状结构。拉曼、核磁共振和 HRTEM 研究表明，BN(C) 区域内的结构演变包括无定形碳的石墨化和 BN(C) 的横向生长，伴随着缺陷浓度的增加。BN（0002）基面内的缺陷是由无序碳嵌入引起的，这反过来决定了BN（C）的形态演变。贫碳整料不发达的微观结构和富碳整料中的过量碳都会降低其机械性能和密度。本文受版权保护。版权所有。