Y2O3耐火材料的制备及其与Zr合金界面反应研究

Preparation of Y2O3 Refractories and Research of Interface Reaction of Y2O3 with Zr Alloy

通过在1650，1700，1750℃下烧结6h制备纯Y203坩埚，并利用Y2O3坩埚真空感应熔炼Zr-4合金。借助x射线衍射（XRD），扫描电子显微镜（SEM），能谱分析仪（EDS）等手段研究了不同烧结温度下制备的Y203坩埚致密度变化，分析了Y2O3耐火材料与锆合金间的界面反应，研究了两者界面反应机制。研究结果表明：1650℃下烧成的坩埚晶粒生长不完全，团聚现象严重，致密度约为87％；1700℃下烧成的坩埚晶粒生长完整，未发现明显的团聚，致密度约为95％；1750℃下烧成的坩埚晶粒生长更加完整，无团聚与二次结晶现象，致密度约为97％；选用1750℃下制备的坩埚熔炼锆合金，熔炼后的坩埚结构完整，界面处没有新相生成，并未见合金熔体渗入现象；熔炼实验后，坩埚与合金界面处有黑色区域生成，可能是由于Y2O3坩埚微结构的变化引起；合金中分布有大量无规则Y的氧化夹杂物；由于Y2O3耐火材料在高温熔体作用下剥落，一部分耐火材料被搅拌人合金熔体中成为夹杂，另一部分分解为Y2O3侵入合金熔体并重新结合生成稳定的Y2O3，过量的O以游离态存在于合金基体中。

Y2O3 crucible was prepared by sintering at 1650, 1700, 1750℃ for 6 h, respectively. And Zr-4 alloy was melted in Y2 03 crucible with vacuum induction melting method. The density change of Y2O3 crucible prepared at different sintering temperature and the interface reaction between zirconium alloy and Y2O3 refractory were examined by X-ray diffraction （XRD）, scanning electron microscope （SEM） , energy dispersive spectroscope （EDS）, then the interface reaction mechanism was explored. The results indicated the grain growth of crucible was incomplete and agglomeration was serious at 1650℃ for 6 h, the relative density was approximately 87%. The grain growth of crucible was complete and no agglomeration was observed at 1700℃ for 6 h, the relative density was approximately 95%. The grain growth of crucible was more complete than that of crucible sintered at 1650 and 1700℃, no agglomeration and secondary crystallization was found at 1750℃ for 6 h, and the relative density was approximately 97%. The crucible prepared at 1750℃ was selected for melting. The crucible Structure was complete and no Zr-4 alloy meh penetration was observed after mehing. However, some black area were generated at the interface of crucible and alloy, which might be due to the change of Y2O3 crucible microstructure. A large number of irregular Y oxide inclusions distributed in the alloy, which was due to that Y2O3 refractory was desquamated under the action of high temperature melt, and one part refractory was stirred into the melt alloy as inclusions, the other part refractory was decomposed into Y and O, and infiltrated into alloy melt and regenerated stable Y2O3 phase, meanwhile, excessive oxygen atoms existed in the alloy substrate as a free state.