John Christopher Ledford (1)
Ledford's Doctoral Thesis, 2021.

Abstract

Additive manufacturing of pure copper has gained traction recently with the possibility of utilizing the numerous benefits including geometrical complexity. However, issues with high oxygen content and rough surfaces deter its application to the production of specialized components such as radio frequency devices. Stringent material properties are required for these devices to operate at peak performance under high power. In this work, we developed techniques to produce pure copper with a low oxygen content that would start to meet the requirements of these demanding applications. Finer powder size distributions were utilized to reduce the surface roughness of fabricated components. This resulted in roughly a 75% decrease in the as fabricated surface roughness with any post processing. A hydrogen heat treatment was implemented on the precursor copper powder to remove increased oxygen content which would allow for the fabrication of pure copper components. An oxygen content reduction of almost 90% was achieved in the final fabricated parts with only 50 ppm wt. of oxygen remaining. Initial studies of implementing a similar hydrogen heat treatment on a layer by layer basis during fabrication is also presented. Lastly, the use of electron emissions for in-situ monitoring during the EB-PBF fabrication process is investigated to aid in the production of high quality, low quantity components.

How Our Software Was Used

Dragonfly was used for the 3D visualization of sample porosity.

Author Affiliation

(1) Department of Industrial and Systems Engineering, North Carolina State University.