First, a thin layer of powder is applied using a recoater system within a vacuum chamber. This layer is rapidly heated by a defocused electron beam, inducing slight sintering of the particles. The weak connectivity between the particles is necessary to provide a minimum of mechanical strength and electrical conductivity. These properties are necessary for the following step when a focused electron beam with high power density is used for selective melting of the current layer cross-section. After lowering the build platform and applying the next powder layer, the cycle is repeated until the desired geometry is reached.
The EBM process requires a vacuum environment and is performed at a base temperature slightly below the melting point of the processed material. Therefore, the evap- oration of volatile alloy elements during melting causes severe metallization on all surfaces, which are not shielded from melt pool exposure. In addition, the interaction between the electron beam and material produces damaging X-ray radiation. In summary, the environment is extremely challenging for most process monitoring devices.
Wolf, T., Fu, Z., Ye, J., Heßelmann, C., Pistor, J., Albert, J., Wasserscheid, P. and Körner, C. (2020), Periodic Open Cellular Raney‐Copper Catalysts Fabricated via Selective Electron Beam Melting. Adv. Eng. Mater.; DOI:10.1002/adem.201901524
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