Electron beam sintering (EBS) process for Ultra-High Temperature Ceramics (UHTCs) and the comparison with traditional UHTC sintering and metal Electron Beam Melting (EBM) processes

Abstract

Ultra-high temperature ceramics (UHTCs) are refractory materials with unusual properties making them strong contenders for applications involving adverse and chemically aggressive environments. This paper presents an effort to process UHTCs using an additive manufacturing method, specifically Electron Beam Sintering (EBS) - adoption of the Electron Beam powder-bed fusion (PBF) process. Such a process shows that the processing and consolidation phenomenon of UHTCs are different from what is observed in the traditional sintering process of UHTCs and Electron Beam Melting (EBM) of typical metals or alloys. In this article, the EBS process of UHTCs is studied. The differences between EBS and the two aforementioned traditional processing methods are analyzed. The scientific hypotheses have been backed by experimental results on a ZrB2 – 30 vol% ZrSi2 UHTC mixture using an electron beam via Liquid Phase Sintering (LPS) theory. Efforts to develop processing conditions to fabricate dense and defect-free UHTC components are explored with the help of finite element (FE) simulations. Characterization of the EBS processed samples using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD) revealed unique needle-like patterned grains of ZrB2 in a ZrSi2 matrix. Our findings demonstrate the feasibility of the EBS process to produce dense layers of UHTCs for coatings, potential three-dimensional, as well as complex-shaped applications.