| Composite material Ag/SnO2 synthesized by chemical reaction was observed its microstructure morphology, before and after it has been squeezed, through SEM,TEM and Electron diffraction instrument, and the phase relationship of the matrix and the second phase was identified. Expatiated on the processes of alloy compounds transforming to the enrichment region, searching the transition state and at last resulting to a stable phase during the reaction, from the standpoint of electron-atom-level and do the theoretical calculation of the new metastable phase which would generate in the process of the entire reaction and the new phase which was observed during the experiment from the standpoint of energy and the thermodynamic stability. It turns out that the activation capability of Sn is better than that of Ag; the participation of oxygen supply was playing a leading role in the reaction process. Search for the characterization of the interface microstructure, such as matrix and the reinforced phase, the new and the reinforced phase. And explain the decomposing free O from the initial reaction mixture is another important way to make the oxidation reaction continually and completely. At last speculate the complete reaction path. In the microstructure of the original burning ingot of the Composite material Ag/SnO2, SnO2 was gathered in ring or cluster state. After the true strain by the extrusion, the SnO2 particles in reinforcement phase diffused to the internal matrix with uniform distribution and small size, the degree of dispersion was enhanced, the role of enhancement was obvious. The Interface between composite materials matrix and the second phase was fresh, the reinforcement pahse particles have a small size. A new phase Ag6O2 in the materials was found during the observation. From the atomic-level analysis, in the interface Group, the degree of integration during Sn of the SnO2 (1-10)/Ag6O2 (101) and O was the most, distribution and energy state density reflected that the two interfaces match best. It explained special problem of lattice matching laying between the second phase particles and new phase perfectly.In the tin-rich region of reaction process, it demonstrated the specific location of 0 in the unit cells of Ag and Sn, the factors of instability of the degree of solute composition in Sn(Ag)-sosoloid and Ag(Sn)-sosoloid, in the energy system.The analysis of the reaction mechanism about matrix-Ag, doped metal-Sn and 0 pointed that the bonding capacity between Sn-O is significantly higher than that between Ag-O, Sn integrates with O will reduce system energy, it explains why O atoms combine with Sn atoms but not Ag atoms through a proliferation of long-range. The absolute value of binding energy in transition phase during reaction process is:Sn2O3-2>Sn2O3-1>SnO>Ag2O3-1>Ag3O4>Ag2O3-2>AgO. The stability of AgxOY-phase is the worst. Enthalpy of formation followed by the size of Ag3O4>Sn2O3-1>Sn2O3-2> Ag2O3-2>Ag2O3-1>AgO. The formation of Sn oxides can be formed easily during the reaction, and more stable than oxide Ag, The most important reason is Sn and O and the role of pro-big Resting on the transition state oxide throughout the reaction process may occur in, Summarized a detailed reaction path in orde.The molecular dynamics theory has proved that Ag2O would start to decompose when its temperature was lower than the decomposition temperature at 440K,500K and 600K in the process of decomposition respectively, and the Atoms movement are not very strong, it means a little amount of movement which was confined to a small area, When the temperature was at or higher than decomposition temperature, Ag2O increased it's decomposition, produce a large number of oxygen source and single-source Ag. The atom internal energy was increased due to the temperature of the outside world. As a result, it played a key role in the process of the follow-up reaction and it set up the reaction model of composite materials Ag/SnO2 synthesized by chemical reaction. Combining with the actual experimental conditions and simulating the process of heating the material, the results showed that:at the begaining of the reaction, the O atom has the highest proliferation, followed by the Sn of lively and higher levels and the last is the inert Ag. In cooling process, the affinity degree of O and Sn is strong than O and Ag. There would be a larger number of precipitated Ag surrounding O atom. The distance between Ag and O is larger and it has formed to the formation of ring to "package" to enhancement phase particle SnOx,。... |
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