二次固溶反应活化烧结制备透明AlON陶瓷及其机理研究

Transparent AlON possesses superior mechanical and optical properties, and is widely recognized as a promising material for various applications in defense field. However, due to the difficulty in fine AlON powder synthesis as well as its strong covalent characteristics, mass transport during sintering is slow, which serious restricts the pressureless sintering of the material. In order to solve the problems, two novel strategies for fine AlON powder synthesis and sintering are proposed in the project. Herein, AlON powder is synthesized through a carbothermal reduction method using core-shell structured Al2O3/C precursor derived from in-situ polymerized Al2O3/polymer hybrid mixture as the starting material, while sintering is accomplished through a secondary solid-solution reaction activated sintering technique with AlON mixture of varied particle compositions as the starting powder. It is expected that the carbon layer on Al2O3 particle surface can play a strong role in retarding the coalescence and growth of Al2O3 during the carbothermal reduction process, thus leading to the formation of fine AlON powder. This plus the activating effect of the secondary solid-solution reaction among AlON particles on sintering can significantly enhance the mass transport and makes the fabrication of transparent AlON through low temperature pressureless sintering possible. . On the basis of the above consideration, the powder synthesis procedure, sintering mechanism and microstructure-property relationship of transparent AlON will be intensively investigated in the project. We hope that the findings from the project may provide valuable guidances not only for the future work on pressureless sintering of transparent AlON, but for the sintering of other types of solid-solution ceramics as well.

透明AlON陶瓷具有一系列优异的力学和光学性能，作为一种重要的国防材料存在着广阔的应用前景。但高纯AlON细粉难合成，加之其自身较强的共价键特性，使得烧成过程中扩散传质缓慢，严重地限制着透明AlON陶瓷的无压烧结。为解决上述问题，本项目以抑制碳热还原合成AlON过程中Al2O3原料粉体颗粒的优先汇聚长大及提高材料烧成过程中扩散传质的热力学驱动力为着眼点，创新性地提出了陶瓷颗粒表面高聚物原位聚合法结合碳热还原合成高纯AlON细粉和二次固溶反应活化烧结制备透明AlON陶瓷的思想，从而为高纯AlON细粉的合成及透明AlON陶瓷的低温烧结提供了有效的途径。在此基础上，深入研究高纯AlON细粉的合成工艺、材料的烧结机制及其显微结构与性能的关系，为未来透明AlON的低温无压烧结制备提供借鉴和理论指导。该项目不仅对于AlON，而且对于其它固溶体型陶瓷的烧结同样具有重要的参考价值。

透明AlON陶瓷具有一系列优异的力学和光学性能，作为一种重要的国防材料存在着广阔的应用前景。但高纯AlON细粉难合成，加之其自身较强的共价键特性，使得烧成过程中扩散传质缓慢，严重地限制着透明AlON陶瓷的无压烧结。为解决上述问题，本项目以抑制碳热还原合成AlON过程中Al2O3原料粉体颗粒的优先汇聚长大及提高材料烧成过程中扩散传质的热力学驱动力为着眼点，创新性地开发了陶瓷颗粒表面高聚物包覆热解碳热氮化合成高纯AlON细粉、宽温区瞬时液相烧结助剂和二次固溶反应活化烧结技术，成功实现了高纯AlON细粉的合成及透明AlON陶瓷的低温无压烧结。所得粉体颗粒尺寸在0.3-0.4um，材料烧结温度仅有1820C，透明AlON直线透过率达到84%，强度和硬度分别达到360MPa和17.5GPa。相对于以往报道，材料烧结温度降低了100C以上，力学和光学性能达到国际先进水平。项目研究成果对于透明AlON陶瓷的低成本制备及其应用推广具有重要的意义。