Preparation and characterization of ZrCO/C composite aerogels
- PDF / 520,250 Bytes
- 10 Pages / 595.276 x 790.866 pts Page_size
- 59 Downloads / 231 Views
ORIGINAL PAPER
Preparation and characterization of ZrCO/C composite aerogels Li Ye • Wenfeng Qiu • Hao Li • Aijun Zhao Tao Cai • Tong Zhao
•
Received: 12 May 2012 / Accepted: 12 November 2012 / Published online: 28 November 2012 Ó Springer Science+Business Media New York 2012
Abstract Zr-containing organic aerogels were synthesized by ligand substitution reaction of polyzirconoxone and 2, 4-dihydroxybenzoic acid, followed by polymerization with formaldehyde, and then supercritical drying using CO2. After carbonization and carbothermal reduction under an argon atmosphere, ZrCO/C composite aerogels with controllable zirconium content (47.8–78.6 wt%) were obtained. The carbothermal reduction was substantially completed at 1,500 °C, and the obtained ZrCO/C composite aerogels exhibit low oxygen contents (9.4–6.7 wt%) and high surface areas (589–147 m2/g). Pore morphologies of the ZrCO/C composite aerogels were investigated in detail by nitrogen sorption measurements, scanning electron microscopy and its associated energy-dispersive X-ray microanalysis measurements. The results show that the aerogels are composed of carbon framework and Zr-conglomerations, and the surface area of aerogel is severely affected by its zirconium content. The presence of reductive ZrC crystals can greatly enhance the oxidation resistance ability of amorphous carbon framework and prevent collapse. Keywords ZrCO/C composite aerogels Carbothermal reaction ZrC Pore structure
L. Ye W. Qiu H. Li A. Zhao T. Cai T. Zhao (&) Laboratory of Advanced Polymer Materials, Center for Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China e-mail: [email protected] T. Cai Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
123
1 Introduction Early transition-metal carbides were widely used for cutting tools and in the abrasive industries because of their high hardness and corrosion resistance [1]. Being a representative example of these materials, zirconium carbide (ZrC) ceramics exhibit high hardness, high melting point, high corrosion and wear resistance, solid-state phase stability as well as chemical stability [2]. Hence, ZrC ceramics are expected to be applied to many high technological fields such as mechanical, chemical and electronic [3–5]. In addition, ZrC is potentially useful as electrode materials, catalysts and catalyst supports because of its metallic character. ZrC is usually produced by direct carbonization synthesis of metallic zirconium, the gaseous pyrolysis of zirconium halide such as ZrCl4 in a carboncontaining atmosphere [6], and the carbothermal reduction (CTR) of ZrO2 with various forms of carbon [7–13]. Due to surface effects/interactions, porous materials often exhibit properties that are distinct from their bulk counterparts [14]. The physicochemical characteristics of porous metal carbide materials are also expected to be determined by their surface area as well as composition. However, the traditional CTR reaction using solid carbon and metal oxide as
Data Loading...
