Investigation on reduction of CoAl 2 O 4 by hydrogen gas using TGA
- PDF / 858,665 Bytes
- 3 Pages / 612 x 792 pts (letter) Page_size
- 24 Downloads / 238 Views
Investigation on Reduction of CoAl2O4 by Hydrogen Gas Using TGA J.A. BUSTNES, N.N. VISWANATHAN, DU SICHEN, and S. SEETHARAMAN The reduction of metallic oxides is an important route for the production of metal and ceramic matrix composites for high technology applications. Experimental investigation on reduction of metallic oxides by hydrogen has special relevance in potential use of natural gas as a reducing agent. In view of this, the Department of Metallurgy, Royal Institute of Technology, has been pursuing kinetic studies on reduction of various complex metallic oxides.[1–5] The present work aims at a study of the reduction kinetics of CoAl2O4. While the study is partially initiated from a theoretical point of view to investigate reduction characteristics of this complex oxide, it is hoped that the investigation could also result in new information and could pave the way to innovation of newer processes. The reduction studies of CoAl2O4 were carried out using a Setaram (Caluire Cedex, France), TGA 92 thermogravimetric analyzer. A schematic drawing of the TGA unit is presented in Figure 1. The analyzer has the resolution of 1 mg and is fully controlled by an IBM PC* through a CS92 *IBM PC is a trademark of International Business Machines Corp., Armonk, NY.
controller. A detailed description of the apparatus has been given in an earlier publication.[6] Cobalt aluminate having a purity of .99 mass pct (approximately 10 mm in particle size) was supplied by Johnson Matthey (Karlsruhe, Germany). In a general run, approximately 20 mg of fine aluminate particles in the form of loosely packed powder bed was kept in a shallow alumina crucible of 8-mm i.d. and 1-mm inner height. The crucible was hung by a Pt suspension wire in the thermobalance and was introduced into the alumina reaction tube. The loosely packed shallow powder bed would allow the reducing gas to have good access to all individual particles. The use of fine particle size would ensure that the diffusion distance for both H2 and H2O was short enough, so that it was possible to focus the study on the chemical reaction at the initial stages of reduction. Before heating, the reaction chamber was first evacuated down to vacuum of 10 Pa and argon gas was introduced
J.A. BUSTNES, Research Metallurgist, is with LKAB, SE-983 81 Malmberget, Sweden. N.N. VISWANATHAN, Assistant Professor, is with the Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology, Mumbai-400 076, India. DU SICHEN, Associate Professor, and S. SEETHARAMAN, Professor, are with the Division of Metallurgy, Department of Materials Science and Technology, Royal Institute of Technology, SE-100 44 Stockholm, Sweden. Manuscript submitted October 20, 1999. 540—VOLUME 31B, JUNE 2000
through the auxiliary gas inlet. The argon gas having a PLUS grade quality, i.e., 99.999 pct pure, was supplied by AGA GAS (Stockholm). The furnace was then heated to the desired reaction temperature under constant argon flow. When the sample temperature was stabilized, argon supply was
Data Loading...
