Oxidation Behavior of Steel and Pure Copper at 500-700°C

The oxidation behavior of steel and pure copper has been investigated in the temperature range of 500-700°C at various oxygen pressures. The rate of oxidation was measured using thermal gravimetric apparatus (TGA). The morphology, composition and structure of the oxide scale were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD).

Thermodynamic and Kinetic Analysis of Ca-Based Oxygen Carrier in Chemical-Looping Combustion

Chemical-looping combustion (CLC) is a promising technology to capture carbon dioxide (CO2) inherently and conveniently without the additional apparatus. At present, for some metal oxide oxygen carriers, the high costs and the positive hazards to the environment inhibit the developing of CLC systems. The feasibility of using CaSO4 oxygen carrier in the CLC system is studied in this paper. Through the thermodynamic analysis, the carbon deposition and the sulfur evolution are studied in the reaction between CaSO4 and a typical syngas. In addition, providing that hydrogen (H2) is fed as the gaseous fuel in the CLC system, the kinetic analysis is investigated on the reduction of CaSO4 by H2 and the oxidation of calcium sulfide (CaS) by oxygen (O2) through the thermo-gravimetric apparatus (TGA). The kinetic models are built on the reduction and the oxidation of the oxygen carrier. The results calculated from the models agree well with the experimental data. Finally, the possible reaction mechanisms for the reduction and the oxidation are explored.

Preparation of ceria-gadolinia electrolytes by the tape rolling technique

The preparation of thin (ca. 200 μm) Ce0.9Gd0.1O1.95 planar electrolytes using the tape rolling technique is described. The processing and formation of these electrolytes involved several steps: (i) the production of a processable ceramic paste, (ii) rolling and cutting, (iii) binder burnout, and (iv) sintering. The rheology of these ceramic pastes is characterized by a hardness indentation test. The materials parameters which may be obtained from the hardness indentation test such as the hardness (plastic flow stress), elastic modulus, and plasticity index are provided. The rheology, as characterized by the hardness method, of the pastes is shown to be influenced by the nature and extent of processing aids and also the mixing and milling times. Further, it is shown that by using a paste formulation with appropriate rheological properties, it is possible to produce uniform thin green tapes using a twin roll mill. The binder burnout characteristics of the ceramic pastes were studied by using a specially constructed thermal gravimetric apparatus. It is shown that the heating rate and the ambient atmosphere have strong influences upon the binder burnout kinetics of these green tapes. Finally, it is shown that sintered Ce0.9Gd0.1O1.9 electrolytes, with a near theoretical density and with a uniform microstructure as well as a chosen near net shape, may be prepared from the corresponding tape rolled greens.