Design of Superplastic Ceramics

研究了采用细分散第二相的超塑性陶瓷的最佳显微结构设计。 晶间硅酸盐相和纳米分散的结晶氧化物将用于通过超塑性变形来制造具有改进的形状成形性能的陶瓷材料。 第二相的体积和分布以及它们的界面能和溶解度将是多晶氧化物中关于晶粒生长、晶界滑动和断裂的分析变量。 实验分析技术将包括分析电子显微镜和阻抗谱以及在室温和高温下的机械变形测试。 这项研究的目的是了解化学上不同的分散剂如何在纳米级使用，以调整氧化物陶瓷的机械性能，因此，高度可变形的陶瓷可以在高温下净成形，同时在较低温度下保持优良的上级机械和电性能。 然而，陶瓷的超塑性变形目前仅在少数保留细晶粒显微结构的有限陶瓷系统中是可能的。 此外，该工艺所需的极高温度和获得的低应变速率限制了该技术的工业应用。 这项研究将集中在优化微观结构的设计参数，将导致在较低的温度超塑性成形和增加的变形速率，同时扩大范围的陶瓷材料，可以通过超塑性成形成形，从而使这项技术成为一个更经济可行的方法净成形陶瓷。

The optimal microstructural design of superplastic ceramics using finely dispersed second phases will be studied. Intergranular silicate phases and nanodispersed crystalline oxides will be used to create ceramic materials with improved properties for shape forming via superplastic deformation. The volume and distribution of second phases and their interfacial energy and solubility will be variables analyzed with respect to grain growth, grain boundary sliding, and fracture in polycrystalline oxides. Experimental analysis techniques will include analytical electron microscopy and impedance spectroscopy as well as mechanical deformation tests both at room temperature and at high temperatures. The goal of this research is to understand how chemically dissimilar dispersants can be used at the nanoscale to tailor the mechanical properties of oxide ceramics, so that highly deformable ceramics can be net shape formed at high temperatures while retaining a superior mechanical and electrical performance at lower temperatures.Superplastic forming has the potential to allow the production of shapes not easily attained by conventional ceramic processing techniques. Superplastic deformation of ceramics currently, however, is currently possible only in a few limited ceramic systems that retain a fine grain microstructure. In addition, the extremely high temperatures required for this process and slow strain rates attained limit the industrial applications of this technique. This research will focus on optimizing the microstructural design parameters that will result in lower temperatures for superplastic forming and increased deformation rates while expanding the range of ceramic materials that can be shaped by superplastic forming, thus making this technique a more economically viable method for net shape forming of ceramics.