【作者】 王守平；

【导师】 孙俊才；

【作者基本信息】 大连海事大学 ， 载运工具运用工程， 2008， 博士

【摘要】 多晶透明氧化铝陶瓷材料是应用于光学、照明、激光等行业的优秀基质材料。本课题研究多晶透明氧化铝的原料-高纯度氧化铝粉的制备及性能，并在此基础上以固相反应烧结法为前提，研究多晶透明氧化铝陶瓷晶相结构的影响因素并以此制作具有均匀晶相结构的透明氧化铝的产品，最终实现高纯度的氧化铝粉和透明氧化铝陶瓷产品的工业化生产。1．通过对硫酸铝铵热解制备高纯氧化铝粉的动力学和热力学的分析以及对所制备的氧化铝粉的前期试验和性能分析，提出和制定了无压三段式热解控制前驱核化速度和晶体长大的速度的新工艺，并通过产业化的规模生产，成功获得了活性高、粒径分布窄、类球形、纯度为99．99％的高纯氧化铝粉。2．通过采用XRD的定性分析，扫描电镜的形貌观察及比表面积的测试等手段，对规模化生产硫酸铝铵热解制备的高纯氧化铝粉进行了全面分析和表征，提出硫酸铝铵热解温度相变的新过程：并提出高纯度的类球形的氧化铝粉的团聚现象为分子间范德华引力引起的软团聚。但原晶粒度大于450nm时（比表面积在小于3．33m²／g）的氧化铝粉，为球形颗粒粉体的分散区。3．通过对该氧化铝粉的不同温度的实际烧结测试，发现其烧结特点是前期的致密化和晶粒长大同时进行，而在后期1420℃-1600℃是粉体烧结致密化的决定阶段，超过1700℃以后是晶粒急剧生长阶段，并拟合给出线形致密化曲线。4．通过研究氧化铝粉的表观性能对多晶透明氧化铝陶瓷晶相结构的影响发现，使用原晶形貌为类球形的氧化铝粉体，有利于六边形氧化铝晶体形貌的形成，其晶体尺寸和粉体的比表面积成反比线形关系；使用低比表面积的粉体有利于其晶体形状和结构的稳定；制备分散性能良好的呈牛顿型流变特征的悬浮体是取得透明氧化铝陶瓷的均匀晶相结构的必须条件。5．通过研究烧结外加剂对透明氧化铝陶瓷的晶相结构的影响发现，MgO在小于1700℃时在晶界能比较高的非{0001}面生成异相镁铝尖晶石，从而在高温时对具有最低界面能的{0001}六边形晶体形状起到钉扎作用，有利于形成均匀六边形的晶相结构，其含量对晶体尺寸大小具有明显的控制作用；ZrO₂和TiO₂均能和氧化铝形成低溶固溶体，促进烧结，在含量一定的条件下，也能形成均匀的晶相结构，但在一定程度上会降低陶瓷的强度和光透过率；而Y₂O₃、La₂O₃由于存在的浓度偏析，对晶体结构容易产生扰乱作用，但可以促进气孔的排除，提高透过率。6．在工业化生产中，通过使用类球形亚微米的氧化铝粉，选择合适的工艺制备路线和工艺参数，在无压气氛烧结中，可以获得晶粒平均尺寸为25μm均匀的晶相结构的透明陶瓷产品，其600nm的单光透过可达50％，达到目前采用固相反应烧结法制作透明氧化铝产品的最好水平。更多还原

【Abstract】 Polycrystal transparent alumina is the better base material used in the fields of optics and illumination and laser etc. In the work, the performance of the high purity alumina powders as material making for transparent alumina are researched and prepared; By adopting solid-state sinter method, the factors effecting on the crystal structures of the transparent alumina are also investigated and the transparent alumina productions with uniform crystal structures are developed successfully; Finally the high purity alumina powders and transparent alumina productions are produced in the industrialization.1 Through research on dynamics and thermodynamic of the process of vitriol salt decomposed in the heating for prepared the alumina powder, the new technics of control crystallization and grain growth speeds by three heating procedures in the non-pressure air is offered and worked out, the 99.99% purity’s powder with characteristic of activity and round-like and grain distributing narrow is obtained in the industrialization.2 The properties of the high purity powder prepared of vitriol salt decomposed in the industrialization is researched and token by X-ray diffraction qualitative analysis and scanning electron microscope and specific surface area test etc., the new phases transfer equation is offered as follows:The soft agglomerates caused by gravitation existing among molecules is the main badly phenomenon in the purity alumina powder, But the alumina powder of original grains’ size over 450nm （specific surface area less than 3.33m²/g） is dispersal area.3 The firing characteristic is that the densification and grain growth are carried out simultaneity less than 1420℃and the densification is sharp in the 1420-1600℃range , the grain growth is mainly over 1700℃. Based on data of firing densification , the densification curves and equations are described.4 By analysis on the apparent properties of alumina powder effecting on the crystal structures of the transparent alumina ceramics, it is founded that the round-like powders is benefit of making the hexagon crystals, its size is inverse ratio with the specific surface area; the alumina powder of lower specific surface area is more in favor of the stabilization of the crystal shape and structures; Al₂O₃ slurry of the Newton type with better dispersing properties is the need condition of forming the uniform crystal structures of the transparent alumina ceramics.5 By Research on different additives effecting on the crystal structures of transparent alumina ceramics, it is founded that MgO-doped is in favor of forming the uniform crystal structures due to the Al₂MgO₄ phase restraining to non-{0001} side with higher interface energy , and it’s content can control the size of the crystals; ZrO₂ and TiO₂ -doped can promote solid-state reaction and form uniform structures , but may reduce the strength and optical transmittance of ceramics in a certain due to forming solid-solutions with lower melting point; Y₂O₃ and La₂O₃-doped may disturb crystal structures due to chroma’s non-equably, but may increase optical transmittance due to enhancing the the green body’s pores eliminating.6 By adopting the high purity alumina powder with like-round grain and appropriate the technics routes and parameters, and sintering in the kiln with non-pressure hydrogen gas, the transparent alumina productions with uniform crystal structures are obtained in the industrialization. The optical transmittance of single light in 600nm is up to 50% and is the best level of used solid-state sinter method .更多还原