宽光谱透明AlON设计及其低温无压烧结制备与性能调控

Transparent AlON possesses superior mechanical and optical properties, and shows great potential for various military uses. However, the sinterability of this material is poor, due to its strong covalent characteristics. This in combination with the low light transmittance at the “atmospheric infrared window” range caused by its short infrared cutoff wavelength seriously restricts its wide-spread application..In order to address the above issue, this project is proposed. The main strategies adopted in the project can be briefly summarized as follows, synthesis of fine AlON powder, adjusting the chemical composition of AlON and the development of efficient sintering aids. In accordance with the above strategies, a new solid reaction method for fine AlON powder synthesis is invented, which uses carbon coated Al2O3/AlN as the starting materials. At the same time, efficient sintering aids enabling transient liquid phase sintering over a wide temperature range are also developed, together with a low nitrogen content design of AlON. It is expected that the synergetic effects of the above three factors can effectively enhance the sintering of transparent AlON and increase its infrared cutoff wavelength, thus realizing the low temperature pressureless sintering of the material and the promotion of its light transmittance in the “atmospheric infrared window” range. The influences of the powder characteristics as well as the nitrogen content and sintering additives on the densification, microstructure and properties of transparent AlON will be studied. The achievements of this project would have profound impacts on the low cost fabrication and property improvement of transparent AlON.

透明AlON陶瓷具有一系列优异的机械和光学性能，在国防领域具有重要的应用价值。但受材料强共价键性等因素制约，透明AlON无压烧结制备非常困难，并且常规透明AlON红外透过截止波长较短，在3-5微米“大气红外窗口”透过率相对不足，致使材料应用发展受限。针对上述问题，本项目以高纯AlON细粉合成、材料组成设计调控和高效烧结助剂开发为突破口，创新性地提出Al2O3/AlN颗粒表面碳包敷反应合成高纯AlON细粉、材料低氮化设计及宽温区瞬态液相烧结的思想。通过三者协同作用，促进材料烧结，并调控其红外透过截止波长，实现材料低温无压烧结制备的同时，有效提高其在“大气红外窗口”的透过率，从而为材料的高效制备和性能优化开辟一条新途径。项目深入研究AlON粉体的合成与性状、材料组成低氮化设计，以及宽温区瞬时液相烧结助剂组成设计等对材料烧结及其显微结构和性能的影响。

透明AlON陶瓷具有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。但受热力学因素制约，高纯AlON细粉合成难，加之目前高效烧结助剂匮乏，致使材料烧结异常困难。目前国际上透明AlON大多采用热等静压工艺制备，材料制备成本高，严重制约其应用发展。为解决上述问题，本项目以透明AlON的无压烧结制备为着眼点，就高纯AlON细粉合成与抗水化处理，以及透明AlON宽温区瞬态液相烧结助剂及其凝胶浇注成型与无压烧结展开研究，取得了多项重要进展：.（1）高纯AlON细粉合成：成功开发Al2O3/AlN复合粉体表面酚醛树脂包覆，结合后续碳热-氮化合成高纯AlON细粉技术，实现在1700°C左右高纯AlON细粉的合成。粉体粉体颗粒尺寸0.3μm左右，且无明显的杂质相。.（2）AlON粉体抗水化处理：通过聚氨酯在AlON粉体颗粒表面的原位聚合包覆，开发AlON粉体抗水化处理技术。所得粉体历经72小时水中静置，亦无明显水解发生。.（3）宽温区瞬态液相烧结助剂开发：成功开发基于稀土氟-氧化物的宽温区瞬态液相烧结助剂，显著提升材料烧结性能，使得材料致密化温度降低约100°C。.（4）透明AlON无压烧结制备：通过无压烧结技术，在1820-1850°C成功实现透明AlON的制备。材料抗弯强度和光学直线透过率分别达到320MPa和86%左右，达到同类材料国际先进水平。.本项目的研究成果对于我国透明AlON陶瓷技术的进步及其应用推广具有重要的意义。