Abstract
Multi-walled carbon nanotube (MWCNT) reinforced alumina-silica fibers were prepared by an in-situ sol-gel method. Aluminum isopropoxide (AIP), aluminum nitrite (AN) and tetraethyl orthosilicate (TEOS) were used as starting materials to prepare spinnable aluminosilicate sol in aqueous media. The mechanical properties and the structures of the MWCNTs reinforced alumina-silica fibers were studied. The results reveal that homogeneous distribution of MWCNTs in alumina-silica fibers improved the mechanical properties of alumina-silica fibers considerably, only 0.5 wt% acid-treated MWCNTs addition in alumina-silica fiber results in 60% increases in tensile strength (397.6±44.7 MPa).
Keywords: sol-gel preparation; nanocomposite; alumina-silica fiber; carbon nanotube; dry-spinning
1. Introduction
Alumina-based fibers have been considered very important ceramic materials because their excellent chemical stability, high temperature strength and low thermal expansion [1]. However, the relatively low tensile strength of alumina-based fibers limited their applications. Carbon nanotubes (CNTs) possess the extremely high tensile strength, good flexibility, and low density [2]. They have become ideal reinforcements for preparation high performance composite materials. Recently, several studies about preparation of carbon nanotubes reinforced alumina ceramic materials have been reported, the mechanical properties of those CNTs-ceramic composite materials were improved considerably [3-6]. Thus, introducing carbon nanotubes into alumina-based fibers might be a feasible way to improve the tensile strength of alumina-based fibers. In this work, we demonstrate an effective method to fabricate MWCNTs reinforced alumina-silica fibers by sol...
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...ich may decrease the fracture origins in the fibers and thus improve the mechanical strength of the fibers.
Table 1 Mechanical properties of pure alumina-silica fibers and 0.5wt% MWCNTs reinforced alumina-silica fibers
Fiber type Tensile strength Strain to failure
Pure alumina-silica fibers 247.4±21.1MPa 1.3±0.4%
0.5wt% MWCNTs reinforced alumina- silica fibers 397.6±44.7MPa 1.1±0.3%
4. Conclusion
In summary, MWCNTs reinforced alumina-silica fibers were successfully prepared by a sol-gel dry-spinning method. Homogeneous incorporation of MWCNTs in alumina-silica fibers makes the 0.5 wt% MWCNTs reinforced alumina-silica fibers exhibiting 60% increase in tensile strength. Further improve the spinning and calcination conditions, will certainly improve the performance of MWCNTs reinforced alumina-silica fibers and these issues might be resolved in near future.
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