菱苦土磨具结合剂物相及显微结构研究

Study of the phase and microstructure of bonds in magnesia abrasives

运用X射线衍射物相分析、电子探针X射线显微分析和差热分析对菱苦土结合剂的物相、显微结构和热稳定性进行了研究。结果显示,在未使用添加剂条件下,当MgO/MgCl2摩尔比等于4.5:1和5:1时,主要物相为318相和方镁石,无518相;MgO/MgCl2摩尔比等于5.5:1和6:1时,518相和318相共存,MgO/MgCl2摩尔比等于6:1时,518相占主要成分;MgO/MgCl2摩尔比等于5:1时,添加少量膨润土或磷酸有利于518相的生成。318相和518相均呈胶凝状包裹在残留氧化镁颗粒上。318相与518相两相共存结合剂的热稳定性与单纯的318相结合剂的热稳定性基本相同。实验表明,物相变化对结合剂的强度没有明显影响,膨润土的加入有利于结合剂强度的提高。

The goal of the investigation is to experimentally demonstrate the phases, microstructures and thermal stability of bond in magnesia abrasives by X-ray diffraction （XRD）, electron probe X-ray mieroanalysis （EPMA） and differential thermal analysis （DTA）. The results show that：with no additives, the main phases are phase 318 and perielase when the molar ratio of MgO/MgC12 is 4.5：1 or 5： 1, no phase 518 is found. When the molar ratio of MgO/MgCl2 is 5.5：1 or 6： 1, phase 518 and phase 318 coexist, and phase 518 represent the main phases when the molar ratio of MgO/MgC12 is 6： 1. When the molar ratio of MgO/MgC12 is 5： 1, a little bentonite or phosphoric acid can improve the formation of phase 518. Phase 318 and phase 518 cover the perielase in a state of gel. The thermal stability of the pure phase 318 is the same as the mixture of phase 318 and phase 518. The bonds composed of different phases have almost the same strength. The additive of bentonite can improve the strength of the bond.