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Carbon nanotubes (CNTs) have attracted much attention as field emitters for x-ray tubes because of their excellent properties such as rapid operation speed, wide operation range, reduced size, light weight, and no necessity of emitter heating. This study fabricated the CNT emitters by screen-printing the CNT paste, followed by firing at 435 °C and vacuum heat treatment at 830 °C. During the high-temperature...
X-ray tubes with an electron source of carbon nanotubes (CNTs) have often been fabricated by vacuum brazing at high temperature, during which CNT emitters have been frequently damaged probably by reacting with other ingredients incorporated into the CNT paste. In particular, some metal or oxide fillers seemed to accelerate the catalytic decomposition of CNTs during high-temperature treatment. In this...
This study investigated the effect of boron and phosphorus compounds on the thermal stability and oxidation resistance of carbon nanotubes (CNTs). Addition of these compounds evidently increased oxidation temperatures of CNTs probably by poisoning chemically their active sites. We applied the CNTs treated with boron and phosphorus compounds to the CNT paste emitters for electron sources of x-ray tubes...
Carbon nanotube (CNT) pastes for field emitters were fabricated by varying the milling speed, CNT amount and glass frit (GF) powder size. The CNTs remained agglomerated at lower milling speeds while they were damaged and shortened at higher speeds. Increasing the amount of CNTs improved the field emission properties, but excessive CNTs led to increased removal of the CNT paste with surface activation...
CNT field emitters have been frequently fabricated by screen-printing CNT paste because this process is easy, scalable, and inexpensive. In order to secure high performance and reliability for CNT field emitters, however, some aspects need to be considered, such as paste adhesion, CNT dispersion in the paste, height uniformity of CNTs, etc. In this study, paste adhesion was improved by engaging nanometer-sized...
Field emission characteristics of CNT paste emitters were improved using the CNTs annealed at high temperatures of 1400∼2000°C in Ar. The annealing considerably enhanced the crystallinity of CNTs, as indicated by an increase of their IG/ID ratios and TGA oxidation temperatures. With such highly crystalline CNTs engaged, the turn-on electric fields and long-term emission stability of the CNT pastes...
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