Carbon nanotubes prepared in situ in a cellular ceramic by the gelcasting-foam method

Abstract

International audienceThe synthesis of carbon nanotubes from an oxide solid solution foam is reported for the first time. A foam of Mg0.9Co0.1Al2O4 solid solution is prepared by the gelcasting-foam method using notably mono- and di-functional acrylate monomers. Using a surfactant in the alkylpolyglucoside family allows to prevent structure changes in the foam before the onset of polymerisation. The wet ceramic foam is dried in air, producing a foam with an open porosity. Total porosity is equal to about 98% and the diameter of the pores is in the range 25-300 mm, about 90% being smaller than 200 mm. The Mg0.9Co0.1Al2O4 foam is reduced in H2-CH4 atmosphere, giving rise to a CNTs-Co MgAl2O4 composite foam. Using the foam instead of the corresponding powder allows a fourfold increase in the production of carbon nanotubes, more than 95% of which have only 1 (70%) or 2 walls

Densification during hot-pressing of carbon nanotube–metal–magnesium aluminate spinel nanocomposites

“…26,29 This is the consequence of an easier supply of the H 2 -CH 4 gas mixture to the catalytic material. We used several Mg 1−x Co x Al 2 O 4 powders (containing or not some MoO x oxide), which were attritor milled, the products being then only partly evaporated.…”

“…The gelcasting-foam method was described in detail elsewhere. 29 By reduction of the IF and GF foams, a series of other CNT-metal-MgAl 2 O 4 composites (C5, C6, CM4-CM9; Table 1) were obtained containing more CNT than those obtained by reduction of the corresponding catalytic materials in the form of powder beds.…”

Growth of One‐Dimensional Nanostructures in Porous Polymer‐Derived Ceramics by Catalyst‐Assisted Pyrolysis. Part II: Cobalt Catalyst

“…Both ceramic honeycombs and ceramic foams have been used as substrates on which different types of 1D nanostructures were created, using different approaches. These include carbon nanofibers (CNFs), [5][6][7][8][9][10][11][12][13] carbon nanotubes (CNTs), [14][15][16][17][18][19][20] or SiC nanofibers. 4,21 Previous works demonstrated that moderate (B30 m 2 /g) to high (B150 m 2 /g) values for the SSA could be obtained, depending on the amount, length, and diameter of the nanostructures.…”

Carbon Nanotube Reinforced Ceramic Matrix Composites- A Review

“…Several methods have been used to form nanotubes inside preexisting porous matrices. Rul et al formed a porous spinel structure with gel casting [9]. This matrix also contained a small amount of Co catalyst, and subsequent CVD produced a relatively high nanotube volume fraction inside the porous oxide.…”