Year of Publication
Master of Science in Materials Science and Engineering (MSMSE)
Chemical and Materials Engineering
Dr. John Balk
Scandate cathode under various processing stages: scandia nano-powder, tungsten scandia mix powder, sintered and impregnated pellets, were characterized with techniques that included electron microscopy, EDS, XPS, and work function measurements. The size and shape uniformity of nano-scale scandia particles changed from round to square and polyhedron during heat treatment. Reduction in size and improvement in size uniformity as heat treating temperature increased were observed. When determining the highest Sc coverage, three assessment methods were used and with their combined results, it was concluded that set VII had the highest Sc at%. In the sintered pellets, it was observed with SEM that more initial scandia coverage in the mix powder sets corresponded to a larger number of scandia particles distributed over the tungsten surface. The structure of the cross section made on pellet surface was porous which was expected in any functional cathode. Kelvin probe measurements revealed that work function values of sintered pellets were similar and decreased by approximately 0.6 eV after the impregnation. A cross section on the impregnated pellet surface revealed that the pores that existed in sintered pellets were gone and filled with impregnated materials that emerged to the surface during impregnation.
Digital Object Identifier (DOI)
This work was financially supported via a Phase II STTR award “Reliable Manufacturing of Scandia-Doped Tungsten Powders for Thermionic Cathodes” (ID numbers N00253-17-C-0014), sponsored by the US Navy.
Zhang, Xiaomeng, "THE STUDY OF SCANDATE CATHODE AND ITS CHARACTERIZATION UNDER VARIOUS STAGES OF PROCESSING" (2019). Theses and Dissertations--Chemical and Materials Engineering. 95.