GOALI: Freeze-form Extrusion Fabrication of Composite Structures Using Ultra High Temperature Ceramics and Refractory Metals

这个赠款机会学术联络与工业（GOALI）项目的研究目标是应用和整合在机械工程和材料科学的理论，以冷冻成型挤压制造工艺制造梯度复合材料结构。密苏里州科技大学与波音公司合作，将研究使用这种新型增材制造工艺制造梯度复合结构的科学和技术，该结构在碳化锆（一种超高温陶瓷）和钨（一种难熔金属）之间具有可控的梯度。多种胶体浆料将由不同原材料（氧化锆、碳、钨、碳和碳化钨）的组合制成，它们将由多台挤出机以不同的比例同时连续挤出，以生产含有反应烧结后设计的分级碳化锆/钨结构的组件。研究将集中在理解流变学和表面化学，以开发高固体含量和良好分散的胶体浆料;自由成型制造过程的建模，分析和控制;以及尺寸精度的评价，机械性能和微观结构的制造零件后处理。该项目预计将产生科学和技术知识的冻结，形成用于制造梯度复合结构的挤压制造工艺。这些知识将有助于其他挤压为基础的自由成形制造工艺。开发的技术将使功能梯度材料的3D组件的无工具制造成为可能，从而提高材料灵活性，降低具有复杂几何形状和高性能要求的小批量组件的制造成本和时间。

The research objective of this Grant Opportunity for Academic Liaison with Industry (GOALI) project is to apply and integrate theories in mechanical engineering and materials science to the Freeze-form Extrusion Fabrication process for fabrication of graded composite structures. Missouri University of Science and Technology in partnership with Boeing will research the science and technology of using this novel additive manufacturing process to fabricate graded composite structures having controllable gradients between zirconium carbide (an ultra-high temperature ceramic) and tungsten (a refractory metal). Multiple colloidal pastes will be made from combinations of different raw materials (zirconium oxide, carbon, tungsten, carbon and tungsten carbide), and they will be extruded by multiple extruders in varying ratios, simultaneously and continuously, to produce components containing a graded zirconium carbide/tungsten architecture as designed after reaction sintering. The research will focus on understanding rheology and surface chemistry for development of high solids loading and well dispersed colloidal pastes; modeling, analysis and control of the freeform fabrication process; and evaluation of the dimensional accuracy, mechanical properties and microstructure of the fabricated parts after post-processing.This project is expected to generate scientific and technical knowledge on the Freeze-form Extrusion Fabrication process for fabricating graded composite structures. This knowledge will be useful to other extrusion-based freeform fabrication processes. The developed technology will enable tool-less fabrication of 3D components with functionally graded materials, thereby increasing material flexibility and reducing manufacturing costs and times for low-volume components that have complex geometry and demand high performance.