【作者】 王宏联；

【导师】 徐德龙； 薛群虎；

【作者基本信息】 西安建筑科技大学 ， 材料学， 2011， 博士

【摘要】 二十世纪七十年代以来,随着世界各国环保意识的增强和我国钢铁、水泥等行业的技术进步,耐火材料的生产也面临着对其性能及环保化的更高要求。在消除“铬公害”的背景下,耐火材料的无铬化成为了一种趋势,寻找新的高性能的无铬化材料替代目前普遍使用的镁铬砖是理论及实践中亟待解决的问题。镁锆砖和镁钙锆砖是目前耐火材料无铬化发展的前沿产品,在目前的研制中,镁锆及镁钙锆材料中ZrO₂的添加一般使用单斜氧化锆,锆英砂等方式引入,由于粒度的原因,使其致密性存在一定的问题,导致镁锆材料的抗侵蚀性、镁钙锆材料的抗水化性仍存在一定问题。Zr（OH）₄凝胶具有低的制备成本及高度分散、均匀性和纳米级粒度的高活性特点,本研究通过凝胶方式引入ZrO₂,研究了其对镁锆及镁钙锆材料性能的影响;同时针对镁钙锆材料的易水化问题,从CaO原料的制备角度研究了如何提高镁钙锆材料的抗水化性能。研究结果表明:（1）对于镁锆材料,在三种引入ZrO₂的方式中,加入单斜ZrO₂的试样抗侵蚀性最好,但挂窑皮性能最差;加入锆英砂的试样虽然挂窑皮性能很好,而抗侵蚀性能最差。加入Zr（OH）₄凝胶的试样性能最好,其抗折和抗压强度也最高。以95电熔镁砂作为骨料配以96电熔镁砂细粉制备的试样性能优于以95电熔镁砂作为骨料配以95烧结镁砂细粉的试样。（2）对于镁钙锆材料,ZrO₂分别以纳米氧化锆和Zr（OH）₄凝胶两种方式引入,试样的最佳烧成温度均为1610℃;加入纳米ZrO₂和Zr（OH）₄凝胶均能提高试样的抗水化性、抗热震性和抗侵蚀性能;Zr（OH）₄凝胶的加入量为12%时,试样抗水化性能最优,纳米ZrO₂的加入量为15%时,试样的抗热震性、抗侵蚀性最好。（3）通过引入添加剂和包裹MgO薄膜两种方式对CaO原料的抗水化性能进行研究。实验发现:①加入FZT（Fe₂O₃、ZrO₂、TiO₂）、FCT（Fe₂O₃、CeO₂、TiO₂）两种复合添加剂明显地促进了CaO材料的烧结,能有效地提高CaO的抗水化性能;两种添加剂的最佳引入量均为2.5%,最佳烧结温度均为1650℃;加入FCT的试样抗水化性能优于FZT。②MgO包裹纯CaO砂的试样抗水化性能优于含添加剂的CaO砂;电熔MgO细粉包裹试样的抗水化性优于轻烧MgO细粉包裹的试样;在CaO砂试样表面包裹引入ZrO₂添加剂的电熔MgO细粉,可在CaO砂表面生成0.1⁰.25mm厚的MgO薄膜层,MgO-CaO过渡层约为0.15⁰.3mm,可降低MgO、CaO之间因热膨胀系数的不同而产生的层裂,能有效地保护内部的CaO砂,使试样具有良好的抗水化性能。更多还原

【Abstract】 High performance demand and environmental protection have been raised on production of refractories due to technology development in iron and steel, cement and other industries as well as enhancement in environmental protection since 1970s. With the need of elimination of "chromium pollution", development of chromium-free refractories is becoming to the major trend. To find new high-performance chromium-free alternative is becoming both theoretical and practical problems to be solved for the current widespread use of magnesia-chrome brick.Magnesia-zirconia and doloma-zirconia bricks are“hot research subjects”for developing chromium-free refractories. The ZrO₂ used as raw material for preparing magnesia-zirconia and doloma-zirconia bricks usually in form of monoclinic ZrO₂ and/or zircon. However, it is difficult to obtain denser product due to ZrO₂ particles size, so as to deteriorate corrosion resistance of materials and decreasing hydration resistance of doloma-zirconia brick. Zr（OH）₄ gel is selected as source of ZrO₂ because of its attractive advantages, such as low processing cost, high dispersion, uniform and reactive. In the present study, the effects of method of adding ZrO₂ derived from Zr（OH）₄ gel on the properties of magnesia–zirconia, and doloma-zirconia bricks are investigated. In additional, from the CaO preparation point of view, how to improve the hydration resistance of doloma-zirconia brick are also studied. Experimental results indicate that:（1） For magnesia-zirconia material, among the three ZrO₂ addition approaches, adding monoclinic ZrO₂ can improve the corrosion performancea, however, clinker adhesions are worse. Although adding of zircon can greatly improve clinker adhesion of material, its corrosion resistance is worse. Samples added Zr（OH）₄ gel have good corrosion resistance and clinker adhesion, which have the highest modulus of rupture and compressive strength. In addition, the properties of samples with 95% fused magnesia as aggregates and 96% fused magnesia fines are superior to that of samples with 95% fused magnesia as aggregates and 95% fused magnesia fines.（2） As for doloma-zirconia materials, the ZrO₂ was introduced by either ZrO₂ nano particles or Zr（OH）₄ gel by using the same sintering temperatures （1610℃）. It was found the addition of nano ZrO₂ and Zr（OH）₄ gel can not only improve hydration resistance but also improve thermal shock resistance and corrosion resistance. Furthermore, we found a serious experimental results: the sample will have the highest hydration resistance by adding 12% of Zr（OH）₄ gel and highest thermal shock resistance and corrosion resistance by adding 15% nano ZrO₂ particles.（3） The improvement in hydration resistance of CaO materials is mainly through by adding MgO additives as well as“core-shell”thin film coating technology. Experimental results indicate:①Samples by using FZT、FCT composite additives with can obviously improve sintering of CaO and effectively increase hydration resistance of materials. It was found that the proper sintering temperature is 1650℃, and the proper addition amount is about 2.5%; The hydration resistance of adding of FCT is superior to FZT.②The hydration resistance of CaO clinker coated with MgO is superior to that CaO contained additives, and that of CaO clinker coated with fused MgO fine particles is superior to clinker coated with light burned MgO fine particles. Coating with 0.1⁰.25mm thickness on CaO clinker can be obtained with coated fused MgO fine particles with ZrO₂ additives, and intermediate layer thickness is in the range of 0.15⁰.3mm. It was expected to protect internal CaO from hydration by decreasing layer crack resulting from mismatch of thermal expansion between MgO and CaO, and samples have the better hydration resistance.更多还原