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Journal of Thermal Analysis and Calorimetry
Authors: J. R. J. Delben, S. S. Rojas, K. Miazato, P. Melnikov, A. A. S. T. Delben, C. X. Cardoso, and A. Job
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Abstract  

Mechanical alloying is a versatile technique for the solid state synthesis of many materials, including alloys such as iron-copper where the elements are immiscible under equilibrium conditions. The structural and magnetic state of these alloys, and their thermal stability, have been investigated by means of thermomagnetometry, DSC, X-ray diffraction and Mssbauer spectroscopy. Comparison of the thermomagnetometry curves for the various alloys together with analysis of intermediate reaction products enabled the individual thermal processes to be identified. The Curie temperature of the alloys was measured, and it was found that on heating the metastable alloys underwent phase segregation between 300-400C.

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Abstract  

The oxidation kinetics of Zr-disilicide (ZrSi2) powders up to temperatures of 1550°C were studied in flowing air using non-isothermal and isothermal thermogravimetric (TG) analysis. During the oxidation process two main thermal events were detected. The first stage of the oxidation reaction leads to the formation of elemental silicon as an intermediate reaction product. Upon further temperature increase the newly formed silicon is oxidized. Completely oxidized ZrSi2 samples consist of ZrSiO4, amorphous and crystalline SiO2 as well as some residual ZrO2. The experimental TG data were analysed with a model-fitting kinetic method. The gas-solid reaction is complex and can best be fitted with a multi-step reaction scheme consisting of branching reactions based on 3D diffusion mechanisms and a fractal order reaction.

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Journal of Thermal Analysis and Calorimetry
Authors: T. Nagaishi, S. Ishiyama, J. Yoshimura, M. Matsumoto, and S. Yoshinaga

The reaction between ammonium sulphate with aluminium oxide was studied. It was confirmed by X-ray diffraction and chemical analysis that three intermediate reaction products, (NH4)3Al(SO4)3, NH4Al(SO4)2 and Al2(SO4)3, are formed. The thermal decompositions of these three compounds were carried out. It has been shown that the same rate law is valid for them. The activation energies for (NH4)3Al(SO4)3, NH4Al(SO4)2 and Al2(SO4)3 are 95.9, 177.9 and 291.0 kj/mol, respectively.

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ignition and afterburning process, it was impossible to obtain meaningful conversion fraction values representing either the overall reaction or a certain intermediate reaction. According to Kissinger method, by plotting versus the reciprocal temperatures

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coordinated with many transition and nontransition metals. Thermal degradation of the oxalate-based complexes is usually complicated and proceeds stepwise through a series of intermediate reactions involving the degradation of one phase and the formation of

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spatial velocity of the fuel (DME or EtOH). The remainder of the mixture mainly consists of excess steam, non-converted fuel (DME or EtOH) and specific intermediate reaction products (acetaldehyde, ethylene, methanol). As discussed before, acetaldehyde and

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concise manner all the intermediate reactions that go on within a cell during growth. It is far less difficult to write a growth-process equation in terms of its initial state comprised of the substances that enter into the composition of the cells that

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