水合氧化铝颗粒表面化学键修饰的研究

Hydratable alumina bonded refractory castables have been used as ladle lining materials. However, the short working time of the castables retard the widely application of hydratable alumina binders. By now, investigations performed on the hydration behavior of hydratable alumina mainly focus on the hydration processes of hydratable alumina and/or hydratable alumina in castables. The results from these research work cannot figure out the key factor affecting the hydration rate of hydratable aluminas. As a result, a clear and direct approach is not provided to adjust hydration rates of hydratable aluminas, especially the hydration rates in the early stage, and thus to control the working time of castables. ..In this project, the ratios of three Al-On polyhedrons/units, especially the proportion of Al-O5 unit, in different hydratable aluminas having varied hydration rates will be investigated. The correlations between Al-On units and hydration rates will be focused on to find out the key factor influencing the hydration rate. Surface chemical bond modification of hydratable alumina will be achieved by MgO doping or micro silica addition to change the proportion of Al-O5 unit and thus to adjust the hydration rate in the early stage of hydratable alumina. Simultaneously, the setting and hardening behavior of castables bonded with MgO doped hydratable alumina or bonded with hydratable alumina with micro silica addition will be investigated to provide theoretical guidance for prolonging the working time of castables.

水合氧化铝结合耐火材料浇注料被越来越多地用作钢包内衬材料，但由于浇注料工作/施工时间短，限制了水合氧化铝的广泛使用。截至目前关于水合氧化铝及其在浇注料中的水化过程的研究多通过分析水化过程以反映水化速率。这些研究手段和结果无法揭示影响水合氧化铝水化速率的根本原因。因而如何控制水合氧化铝的水化速率，以调控浇注料的施工时间还没有找到明确的途径。..本课题拟系统研究水化速率不同的水合氧化铝中三种Al-On多面体比例的差异，尤其是Al-O5多面体比例的不同，查明Al-On多面体比例的差异与水化速率之间的关系，揭示影响水化速率的根本原因。通过MgO掺杂或加入氧化硅微粉，对水合氧化铝颗粒表面进行化学键修饰，改变表面Al-O5多面体的比例，以调节水合氧化铝水化初期的水化速率。同时，也要研究MgO掺杂和加入氧化硅微粉对浇注料凝结硬化的影响，为调控浇注料的施工时间提供理论依据。

研究发现，与Al-O4和Al-O6多面体相比，水合氧化铝颗粒中Al-O5多面体易与水发生反应，从而导致了水合氧化铝水化速率快，尤其是水化初期的水化速率快。MgO掺杂或加入氧化硅微粉可以减少Al-O5多面体的比例，延缓了水合氧化铝水化初期的水化速率；机械研磨或无机盐与水合氧化铝共混可以减少与水直接接触的Al-O5多面体的比例，从而延缓了水合氧化铝水化初期的水化速率。MgO掺杂、机械研磨、无机盐共混或加入氧化硅微粉，延缓了水合氧化铝水化速率，减弱了水化产物生成，从而延长了水合氧化铝结合浇注料的可施工时间，但降低了浇注料的脱模强度。本工作首次采用固体核磁共振（MAS-NMR）结合水化放热、XRD、SEM、热分析系统研究了水合氧化铝的水化行为与Al-On多面体比例变化之间的关系。..本课题研究了水化速率不同的水合氧化铝中Al-On多面体比例的差异，尤其是Al-O5多面体比例的不同，查明了Al-On多面体比例的差异与水化速率之间的关系，揭示了Al-O5多面体比例高是导致水化速率快的根本原因。通过MgO掺杂、机械研磨、无机盐共混或加入氧化硅微粉，对水合氧化铝颗粒表面进行化学键修饰，改变了Al-O5多面体的比例，延缓了水合氧化铝的水化速率，提高了浇注料的流动性，降低了浇注料的脱模强度，为调控浇注料的施工时间提供了理论依据。

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