透明陶瓷纳米化增韧及塑性变形机理研究

Transparent ceramic as an optical-functional material has inherent brittleness which greatly affects the stability, reliability and operating limit of transparent ceramic devices. However, traditional toughening methods are not suitable for transparent ceramic. It is important to develop a toughening method for transparent ceramic. Current project aims at the toughening mechanism and plastic deformation mechanism of nancrystalline transparent ceramic. Firstly, the alcohol-water coprecipitation method and super high pressure sintering technology will be used to prepare nanocrystalline transparent ceramic. During the sintering process the grain growth will be restrained by controlling sintering temperature and pressure. The toughness of nanocrystalline transparent ceramic will be evaluated by indentation method. The in-situ microtest will be used for investigating the crack propagation behavior of nanocrystalline transparent ceramic. Meanwhile, the toughening mechanism will also be investigated. The microstructure of the plastic deformation zone of nanocrystalline transparent ceramic will be analyzed based on nanoindentation and transmission electron microscope. And then the plastic deformation behavior and mechanism of nanocrystalline transparent ceramic will also be revealed. Current project will provide the experimental and theoretical guidance to improve the brittleness of transparent ceramic material.

透明陶瓷作为一种光功能材料，它固有的脆性极大的影响了透明陶瓷器件的稳定性、可靠性和工作极限。然而，传统陶瓷增韧技术都不适用于透明陶瓷。故急需发展一种适宜透明陶瓷的增韧方法。本项目拟开展透明陶瓷纳米化增韧及塑性变形机理的研究。首先利用醇水共沉淀法结合超高压烧结技术，通过调控烧结温度和压力，抑制晶粒生长，实现透明陶瓷烧结体的致密化和纳米化。随后利用压痕法对纳米透明陶瓷的增韧效果进行评价，并利用原位显微微力试验系统对纳米透明陶瓷的裂纹扩展行为进行研究，揭示透明陶瓷纳米化增韧机制。基于纳米压痕和透射电子显微镜技术，对纳米透明陶瓷纳米压痕塑性变形区微观结构进行解析，研究纳米透明陶瓷塑性变形行为，揭示纳米透明陶瓷塑性变形机理。最终为改善透明陶瓷脆性，实现透明陶瓷的强韧化提供坚实的实验和理论依据。

利用超高压低温烧结技术成功制备了平均晶粒尺寸仅为7.8 nm的完全致密纳米晶锆酸钆（GZO）透明陶瓷。采用压痕法对纳米晶和粗晶GZO透明陶瓷的断裂韧性进行对比测试，随后利用原位微柱压缩试验对纳米晶GZO透明陶瓷微柱的压缩性能及塑性变形行为进行了研究。结果表明：（1）纳米晶GZO透明陶瓷的断裂韧性提高近2倍，其增韧机制主要由裂纹扩展的偏转效应及裂纹尖端孔洞效应导致；（2）GZO陶瓷微柱展现出了可与金属相媲美的塑性变形能力，最大压缩应变可达~17%，其变形机制任然由位错滑移主导。