Growth of Carbon Nanotube Forests on Carbon Fibers with a SiO 2 Interlayer
- PDF / 318,900 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 53 Downloads / 224 Views
Growth of Carbon Nanotube Forests on Carbon Fibers with a SiO2 Interlayer Erica F. Antunes2, Viviane Q. da Silva1, Vagner E. C. Marques1, Lilian Siqueira1, and Evaldo J. Corat1 1 Laboratório Associado de Sensores e Materiais, Instituto Nacional de Pesquisas Espaciais, CP 515, 12227-010, São José dos Campos, SP, Brasil 2 Instituto de Ciência e Tecnologia, Universidade Federal de São Paulo, 12231-280, São José dos Campos, SP, Brasil
ABSTRACT Ceramic barriers avoid catalyst diffusion to produce better multiwall carbon nanotubes (CNT) on carbon fiber fabrics (CF). We developed a simple method to produce efficiently a silica layer from TEOS pyrolysis at similar conditions of CNT growth from camphor and ferrocene mixtures. This protective layer prevents iron diffusion and allows the vertical alignment of CNTs. INTRODUCTION Nowadays the literature has given special attention in producing laminates with vertically-aligned carbon nanotube (CNT) films among the plies. This is known as “nanostitching”. Composites of ceramic fiber fabrics (SiC, Al2O3) coated with aligned CNTs have shown gains up to 348% at interlaminar fracture toughness (GIC) [1-4]. Carbon fibers (CF) are more commonly commercialized than the ceramic fibers, but metal diffusion is a critical problem on growing CNTs on CF. In 2010, our research group published a paper on deposition of amorphous silicon coatings on CF, before depositing vertically-aligned CNTs [5]. Although an efficient way to avoid iron diffusion, the plasma enhanced process used is not easily scalable. Other groups [6,7] have invested efforts in production of ceramic nanocoatings, mainly Al2O3 and SiO2. Feng and co-workers [6] coated CF with Al2O3 from a 0,1 M solution of aluminum nitrate, followed by a heating to 250oC at rating of 2oC/min. Fv and co-workers[7] got a solid SiO2 coating from a hydrolysis, followed by a pyrolysis a solution of toluene with 5 vol.% tetraethoxy silane and 5 vol.% silicon tetrachloride. At current work, we have developed a CF coatind made of amorphous-SiO2 for deposition of vertically-aligned CNT from camphor/ferrocene pyrolysis. We established a simple way to coat the CF fabrics from TEOS pyrolysis, at similar conditions of CNT production. A study of the deposition time of SiO2 layer evaluated the minimal thickness for this layer works as barrier against iron diffusion. EXPERIMENTAL DETAILS The SiO2 layer was deposited on CF surface before CNT growth. Three pieces of the polyacrylonitrile-based CF cloths (Texiglass, CCS200) were simultaneously placed into the
97
oven. The reaction happened inside a quartz tube with 4 cm of internal diameter. Each piece sized 170 x 35 mm, but the reaction zone measured only 150 mm. The SiO2 deposition was achieved by the decomposition of tetraethyl orthosilicate (TEOS, Si (OC2H5)4) at 700 ºC, at selected times (1, 3, 5 and 10 min). Before pyrolysis step, the TEOS bottle was evacuated at 10-2 Torr, filled with N2, heated at 140oC, and the vapor was carried to the reaction zone by a N2 flow of 1.5 LPM. The CNTs grew in the same
Data Loading...
