白云鄂博尾矿含量对微晶玻璃析晶特性和性能的影响

以白云鄂博某尾矿为主要原料、以Cr2O3为晶核剂制备尾矿微晶玻璃,使用DSC、XRD、SEM、TEM以及Raman光谱等手段对其表征并测试其析晶特性、抗折强度、维氏硬度和耐酸性,研究了尾矿含量对其析晶特性和性能的影响。结果表明,微晶玻璃的主晶相由辉石相和钙铝黄长石相构成,其中晶核剂Cr2O3因形成尖晶石晶核诱导辉石相析出。随着尾矿含量的提高微晶玻璃的力学和耐腐蚀特性呈现降低的趋势。其原因是,尾矿含量的提高使CaO的含量过高,在晶体的生长过程中滑动和迁移受阻进而在微晶玻璃中产生空洞和缺陷。同时,微晶玻璃中钙铝黄长石相/辉石相比例增大也不利于其性能的提高。白云鄂博尾矿中共生的稀土元素在晶界处形成铈钙硅石第二相,可减小晶界面积并降低晶界总能量,有助于提高微晶玻璃的力学和耐腐蚀性能。

Effect of Bayan-Obo Tailings Content on Crystallization Characteristics and Properties of Glass-ceramics

Metallic tailings built glass-ceramics were prepared with Bayan-Obo tailings as the main raw material and Cr₂O₃ as nucleating agent. The crystallization characteristics of tailings built glass-ceramics were characterized by means of DSC, XRD, SEM and Raman spectra and the properties of glass-ceramics were evaluated by bending strength, Vickers hardness and acid resistance tests. Results show that the glass-ceramics are mainly composed of crystalline phases of diopside and gehlenite, while the nucleating agent of Cr₂O₃ can promote the precipitation of the main crystalline phase of diopside by forming spinel. The mechanical and corrosion resistance characteristics of glass-ceramics showed a decreasing trend with the increase of tailings content. The higher CaO content caused by the increase of tailings content can lead to the obstruction of sliding and migration of crystalline phases in the crystal growth process. As a result, it was easy to produce cavities and defects in glass-ceramics. Meanwhile, the increase of the ratio of gehlenite/diopside was not conducive to the improvement of the properties of the glass-ceramics. In addition, the rare earth elements intergrowth in Bayan-Obo tailings can form the second phase of cerium calcium silica at the grain boundary, which can reduce the area and the total energy of grain boundaries, which was helpful to improve the mechanical and corrosion resistance of glass-ceramics.