NiO对镁铝尖晶石反应烧结性能的影响

本文以高纯电熔镁砂和煅烧活性氧化铝粉为原料,以氧化亚镍(NiO)为添加剂,通过传统固相烧结法制备镁铝尖晶石材料。将MgO和Al₂O₃粉按理论摩尔比1∶1进行配料,在体系中分别引入质量分数为0%、0.5%、1.0%、1.5%、2.0%的NiO。利用X射线衍射(XRD)仪、扫描电子显微镜(SEM)和能谱仪(EDS)对烧结后试样进行分析,研究了NiO的添加对MgAl₂O₄材料烧结性能、物相组成及显微结构的影响。结果表明:引入适量的NiO可以显著促进MgAl₂O₄相的形成以及晶粒的发育长大;在1 600 ℃时,当NiO含量低于1.5%时,NiO能完全溶入MgAl₂O₄晶格并优先取代Al³⁺,提高了MgAl₂O₄晶体内部的缺陷浓度,活化了晶格,从而促进MgAl₂O₄的烧结。当NiO含量高于1.5%时,其内部开始出现较多第二相NiO,阻碍了物质的迁移和传输,反而不利于MgAl₂O₄烧结性能的提高。

Effect of NiO Addition on Reaction Sintering Performance of MgAl2O4

In this paper, magnesium aluminate spinel (MgAl₂O₄) materials were prepared by traditional solid-phase sintering method with high purity fused magnesia and calcined active aluminum powder as raw materials, and NiO as additive. The MgO and Al₂O₃ powders were mixed in a theoretical molar ratio of 1∶1, and NiO with mass fraction of 0%, 0.5%, 1.0%, 1.5%, and 2.0% NiO were introduced into the system, respectively. The effects of NiO addition on sintering properties, phase composition and microstructure of MgAl₂O₄ were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that the introduction of appropriate amount of NiO can significantly promote the formation of MgAl₂O₄ phase and grain growth. At 1 600 ℃, when the NiO content is lower than 1.5%, NiO can completely dissolve into MgAl₂O₄ crystal lattice and preferentially replace Al³⁺, which improves the defect concentration in MgAl₂O₄ crystal and activates the lattice, thus promoting the sintering of MgAl₂O₄. When the NiO content is higher than 1.5%, more second phase NiO appears in the MgAl₂O₄, which hinders the mass migration and transmission, and it is not conducive to the improvement of sintering performance of MgAl₂O₄.