Zirconium diboride nanofiber generation via microwave arc heating

Abstract

Ultrahigh temperature zirconium diboride nanofibers were produced by microwave arc heating using micron-sized raw powder. While microwave heating the ZrB(2) powder, the development of local arcing led to rapid heating and solidification of the samples, along with the creation of nanofibers. The morphology of these high aspect ratio nanofibers was characterized using scanning electron microscopy and transmission electron microscopy. Energy dispersive x-ray spectroscopy, electron energy loss spectroscopy and selected area electron diffraction showed the composition to contain zirconium, boron, nitrogen, aluminum and oxygen as well as the crystallographic orientation. ZrB(2) nanofiber applications include aerospace and other harsh environments.

Modern Microwave Methods in Solid-State Inorganic Materials Chemistry: From Fundamentals to Manufacturing

“…MW arc heating has also been utilized in formation of ZrB 2 nanofibers from the bulk boride. 120 Commercially available ZrB 2 was heated in air inside a 2100 W MMC with a mode stirrer (used to increase the homogeneity of the heating) for 10−45 s per treatment with a variable number of treatments (<5). Use of a 100 mL alumina crucible resulted in arcing in the reactant powder.…”

Nanostructures from Zirconium Diboride and Alumina Ceramics

“…For both standard refractory materials and UHTCs, processing remains a challenge. Sintering a powder of UHTCs can be accomplished by hot pressing 12 or heating with an electric furnace, 13 microwave, 14 laser, 15 or electron beam (C. N. Sun, M. C. Gupta, & K. M. Taminger, unpublished data) etc. ZrB 2 can be sintered at temperatures as low as 1400°C using additives, although densification occurs much more rapidly at higher temperatures 16 .…”

“…Alternatively, arc heating can create a local plasma hot enough to sinter UHTCs. Arc heating only works if the compound is electrically conductive like ZrB 2 , 18 which has thermal and electrical conductivities similar to iron or lead 14 . By combining microwave heating with arc heating, the local temperature of the powder may reach extremely high temperatures, causing interaction between ZrB 2 and alumina.…”