| AVS 57th International Symposium & Exhibition | |
| Vacuum Technology | Tuesday Sessions |
| Session VT-TuP |
| Session: | Vacuum Technology Poster Session and Student Posters |
| Presenter: | J. Manura, Scientific Instrument Services |
| Authors: | J. Manura, Scientific Instrument Services R. Shomo, Scientific Instrument Services C. Baker, Scientific Instrument Services |
| Correspondent: | Click to Email |
Historically filaments used in most scientific instruments have been constructed from pure Rhenium. Rhenium has been the preferred material due to its resistance to oxidation and good emission qualities. However, Rhenium tends to be soft and has a tendency to warp and change shape during its operation. A new Yttria/Rhenium alloy has been developed for the purpose of improving the performance of filaments used in analytical instrumentation. The Yttria/Rhenium alloy filament exhibits the same electrical properties as pure Rhenium but has the advantage of not warping or changing shape, thereby improving the performance and lifetime of filaments used in analytical instrumentation.
Yttria alloys of rhenium were formed by sintering various concentration of yttria into rhenium. The sintered yttria/rhenium alloy bars were then drawn down to wires with diameters between 0.010” and 0.003”.
Pure Rhenium filaments and Rhenium/Yttria alloy filaments of different configurations were tested to compare their properties. Testing was done using a custom filament station to measure the various filament electrical characteristics. Filaments were also tested in commercial instruments to monitor their performance. Electron microscopy studies were performed to study the grain characteristics..
Electrical studies in the filament testing station on pure rhenium filaments and various Yttria/Rhenium alloy filaments demonstrated that Yttria/Rhenium alloy filaments exhibited similar electrical properties as Rhenium. This enables these new alloy filaments to be used interchangeably with the standard rhenium filaments in analytical instrumentation.
Studies on the rhenium/yttria alloy filaments in commercial instruments demonstrated increased cycle lifetime as compared to standard rhenium filaments. The enhanced lifetime was attributed to the improved structural strength of the Yttria/Rhenium alloy filament. The Yttria/Rhenium filaments manufactured into different configurations all demonstrated less tendency to sag, warp or change shape as compared to pure Rhenium filaments.
Electron microscopy studies demonstrated that yttria oxide particles intermixed with the rhenium particles which minimized the grain growth in the alloy filament. In comparison, the pure rhenium filaments exhibited larger grain sizes. This smaller grain size in the alloy filament appears to strengthen the filament wire to provide a more stable filament that displays less sag or warping than pure rhenium filaments. The property of holding its shape has been demonstrated for multiple configurations. The Yttria/Rhenium material improves the performance of emission filaments used in analytical instrumentation.