High Toughness Textured Ceramics for Biomedical Use

描述：牙科对结合了与天然牙齿相匹配的高强度和光学性能的陶瓷有很高的要求，在具有更高韧性的生物活性陶瓷的重建外科中也有很高的要求。我们之前的工作导致了一种新型微晶玻璃的开发，这种微晶玻璃可以使用传统的实验室技术进行压制。这种材料表现出织构的组织和改善的韧性。这项提议的总体目标是开发一种结合了高强度和优秀美学的牙科微晶玻璃。另一个目标是生产韧性更高的生物活性陶瓷。织构材料的韧性与织构程度和显微组织直接相关。我们生产高强度牙科陶瓷的方法是优化结构，促进亚微观二次云母相的形核，并减少压制产品中的缺陷密度和尺寸。纹理细化将通过两种技术实现：在温度梯度中进行热处理，然后进行热压或在热压后对玻璃进行热处理。通过添加AlPO_4作为成核剂，可以改变材料的微观结构。通过添加La203来增加玻璃基质的折射率，从而减少晶相和玻璃相的折射率失配，将改善半透明性。通过消除压制后存在的表面层，以及通过对压制的陶瓷进行热处理以促进裂纹愈合，可以减少缺陷密度和尺寸。通过热压可制得韧性提高的织构型生物活性陶瓷。通过热分析、X射线衍射仪和扫描电子显微镜对其晶化行为和热性能进行了研究。用扫描电子显微镜和X射线衍射仪对其织构程度进行了研究。将用X射线反射仪和能谱仪对表层进行分析。机械和光学性能将在有纹理的、未有纹理的和商业上可获得的陶瓷上进行测量作为对照。实验设计采用了一种自适应采样方案来优化光学和机械性能，并将不同的目标结合在一起。潜在的应用包括牙科修复、牙科种植超结构和骨替代植入物。

DESCRIPTION: There is a high demand in dentistry for ceramics that combine high strength and optical properties matching those of natural teeth, and in reconstructive surgery for bioactive ceramics with improved toughness. Our previous work has led to the development of a novel glass-ceramic that is pressable using conventional laboratory techniques. This material exhibits a textured microstructure and improved toughness. The overall objective of this proposal is to develop a dental glass-ceramic that combines high strength and excellent esthetics. An additional goal is to produce bioactive ceramics with improved toughness. Toughness in textured materials is directly related to the degree of texture and microstructure. Our approach to producing high strength dental ceramics is to optimize the texture, promote the nucleation of a submicroscopic secondary mica phase and reduce flaw density and size in the pressed product. Texture refinement will be achieved via two techniques: heat treatment in a temperature gradient followed by heatpressing or heat treatment of the glass after heat-pressing. Microstructure will be tailored by adding AIPO4 as a nucleating agent. Translucency will be improved by adding La203 to increase the refractive index of the glassy matrix, thereby reducing the mismatch between the indices of crystalline and glassy phases. Reduction in flaw density and size will be achieved by eliminating the surface layer present after pressing and by heat treatment of the pressed ceramic to promote crack healing. Textured bioactive ceramics with improved toughness will be produced via heat pressing. The crystallization behavior and thermal properties will be studied by thermal analysis, XRD and SEM. The degree of texture will be investigated by SEM and XRD. The surface layer will be analyzed by X-ray reflectometry and EDS. The mechanical and optical properties will be measured on textured, non-textured and commercially available ceramics as controls. The experimental design uses an adaptive sampling scheme to optimize the optical and mechanical properties and integrate the different aims. Potential applications include dental restorations, dental implant superstructures, and bone replacement implants.