Mechanical Properties of Metal Oxide Aerogels

Abstract

In this study we report on mechanical properties of molded, single component Al 2 O 3 , Ga 2 O 3 , Fe 2 O 3 , and ZrO 2 as well as mixed aerogels, made from yttrium stabilized zirconia, yttrium aluminum garnet, and zinc aluminum spinel. Initially all aerogels were produced equally in molded bodies by a facile epoxy method and were annealed afterward at 300 °C. Then we performed uniaxial pressure tests on cylindrical aerogel monoliths to gain Young's modulus which depends on composition, density, and posttreatment. Already pure aerogels like ZrO 2 show wellpromising Young's modulus of 10.7 MPa, whereas most popular SiO 2 materials display a modulus between 2 and 3 MPa at comparable densities. Moreover we focused on Al 2 O 3 aerogels which exhibit high stability and interesting densification behavior depending on the annealing temperature. On the basis of this observation, we combined the toughness of the Al 2 O 3 scaffold with the extraordinary hardness of ZrO 2 , by adding up to 20 atom % Zr, to increase the specific Young's modulus. For the mixed material with a Zr content of 20 atom %, we reach a record value for compressible aerogels of 125 MPa mL g −1 .

Versatile route to core–shell reinforced network nanostructures

“…In fact the studies of mechanical properties have been reported only for organic aerogels, 44,45 carbon aerogels 46,47 or silica aerogels 48,49 and recently for other metal-oxide aerogels. 50 In this work a compression test was employed to evaluate the mechanical stability of silica shell modified and unmodified NANONETSs. As the dimensions of the NANONETS are small, and as the forces the samples are subjected to are also very small, it is not possible to actually measure the Young's modulus (which is usually done in the area of elastic deformation at low strain levels).…”

Emerging Dual‐Channel Transition‐Metal‐Oxide Quasiaerogels by Self‐Embedded Templating

“…Currently, the main‐group metal oxide aerogels (i.e., SiO 2 , ZrO 2 , A1 2 O 3 , Ga 2 O 3 ), are typically prepared through the sol–gel transition from metal alkoxides precursors and subsequent supercritical drying. [ 30–33 ] However, the metal alkoxides are usually toxic and expensive, and the overall fabrication process is high energy‐consuming. [ 34 ] More importantly, low‐valence state transition‐metal alkoxides (e.g., Co, Ni, Mn) have poor stability and fast hydrolysis rate, inevitably resulting in the collapse of the pore structure and uncontrollable particle size of as‐prepared TMO aerogels.…”

Hybrid Materials Based on Carbon Nanotubes and Nanofibers for Environmental Applications

“…Different types of inorganic coatings can be created depending on the precursors used. For example, the hydrolysis of titanium isopropoxide resulted in a titanium dioxide matrix (Kim et al, 2011 ; Li et al, 2011 ; Hamid et al, 2014 ; Ge et al, 2015 ); iron (III) nitrate–iron (III) oxide matrix (Sun et al, 2005 , 2018 ; Hassan et al, 2013 ; Wan et al, 2015 ); and also probably the creation of ZrO 2 , HfO 2 , and Ta 2 O 5 oxide gels (Miller and Ko, 1996 ; Benad et al, 2018 ; Kiselev et al, 2019 ). Fixing elemental oxide on CNTs or CNFs surfaces changes hybrid materials characteristics.…”