Owing to their high melting points and ability to resist extreme thermal stresses, ultra-high temperature ceramics (UHTCs) are important materials for critical applications, such as hypersonic flights, space re-entry vehicles, and rocket engines. Traditional manufacturing processes restrict the freedom to manufacture UHTCs with complex geometries due to the limitations of die and mold designs. Electron beam melting (EBM) is an established powder-bed layer-by-layer additive manufacturing (AM) process for metal parts. In this research, an effort has been made to EBM-process UHTC-based materials, and to investigate the microstructures of the fabricated materials under different processing conditions.<br/>For the EBM fabrication of ZrB2- 30 vol% ZrSi2 composites, the optimal processing parameters has been simulated with a mathematical model. The results have been compared to the experimental observations to valid the results and to obtain the optimized processing condition. This study demonstrates the capability for AM of UHTCs with complex geometries by the EBM technique.<br/>The ultimate goal of this project is to create turbine blades with complicated geometries or curvatures and internal cavities using the EBM process, to make functionally-graded refractory metal-ceramic composite/compound structures. If successful, it is able to create turbine blades with desired thermal-mechanical properties as well as complex geometric requirements, e.g. with cooling channels and sharp curvatures. The composition of the metal phase and the ceramic phase can be optimized and varied as each layer built up during the process. The processing of the powder particles is dependent on the electrical conductivity, the thermal properties and the melting points of the starting powders.

Additive manufacturing of UHTC materials using an electron beam melting (EBM) process

ACS Spring 2022

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