Kinetics of formation of nanaocrystalline phases by mechanochemical reaction between Ti and RuO2

摘要

The structual evolution of a mixture of Ti and RuO2mechanically alloyed over a period of 40 h was followed withrespect to time by X-ray diffraction. The structural parameterswere extracted from the XRD traces by performing a Rietveldrefinement analysis. The phase formation occurs in three distinctstages. In stage I (first 10min of milling), RuO2 and Ti reacts toform RuTi, Ru, and TiO, with some other oxide phases of titanium(Ti2O3, and TiO2). In stage II(between 10 and 60 min), the reactionslows down and the titanium dioxides are being reduced. In stageIII, decomposition of RuTi through reaction with Ti2O3 occurs, toyield to the formation of TiO and Ru. In stage I, the reaction rate isvery high, for example, 34.7wt% of RuTi is formed after only 10min of milling. It is argued that such rapid reaction rate is due tothe enthalpy of the redox reaction occurring between Ti and RuO2which raised the local temperature and thus favors the atomicinterdiffusion. Finally, a series of experiments performed s afunction of the milling intensity points to the existence of anenergy threshold below which the combustion reaction between Tiand RuO2 does not occur.