Study On The Reaction Kinetics Of Micro And Nano Ti Powders With Inerting Powders

Accidental fire and explosion of titanium powders seriously restrict the development of titanium industry.According to the moderate principle in the intrinsically safe theory,adding titanium dioxide with no explosion hazard into titanium powders with greater explosion hazard can reduce the risk of material itself and dust explosion risk.To this end,this paper studied the reaction kinetics characteristics of micro and nano Ti powders with TiO2 particles through thermal analysis.It aims to explore the inerting mechanism of TiO2 particles to micro and nano Ti powders on the basis of fire and explosion reaction mechanism of titanium powders,so we can find a new way to essentially prevent the explosion of micro and nano Ti powders.Firstly,this paper studied the morphological characteristics and particle size distribution of micro/nano Ti powders and micro/nano TiO2 by the laser particle size analyzer and scanning electron microscopy.The results show that the nano Ti powders are different from the micro Ti particles,it shapes accumulation and the size of the particle group is far less than that of micro titanium powder.Secondly,We studied the the thermal analysis curves of micro and nano Ti powders in air and N2 under four kinds of heating rate5,10,15,20 K/min through the German NETZSCH STA449C thermal analyzer;for the study of inerting mechanism of inerting powders to micro and nano Ti powders,we studied the thermogravimetric curves of micro and nano titanium powders in different inerting levels.Lastly,to determine the reaction mechanism of micro and nano Ti powders in air?inerting gas and with inerting powders,this paper calculated the activation energy and the preexponential constant of pure micro and nano sample at different heating rate using KAS,and obtained the most probable mechanism functions using the Coats-Redfern integral method,and calculated the action energy and the preexponential constant.Through a series of research and analysis,we concluded the following conclusions:the thermogravimetric curves can be divided heating process into two stages:gas absorption and desorption stage and gas weight gain stage;the gas weight gain stage of nano Ti powders and its mixture can be divided into the rapid weight gain stage and slow weight gain stage;the fire performance and combustion stability of nano Ti powders are better than micro Ti powders;the fire performance and combustion stability of micro and nano Ti powders in air are better than those of micro and nano Ti powders in N2 and with inerting powders;the fire performance and combustion stability of micro and nano Ti powders with umTiO2 are better than those of micro and nano Ti powders with nmTiO2;the KAS method is not suitable for micro/nano Ti powders in air and nano Ti powders in N2,it is just suitable for micro Ti powders in N2,the average activation energy value is 202.2kJ/mol;the reaction mechanism function is Jander;the action energy and the preexponential constant of micro Ti powders in air increase with the increasing of heating rate,and they are much larger than those of nano Ti powders in air,the action energy and the preexponential constant of the rapid weight gain stage of nano Ti powders are greater than the slow weight gain stage;the action energy and the preexponential constant of micro Ti powders in N2 increase with the increasing of heating rate,and they are slightly greater those of micro Ti powders in air,and much larger than those of nano Ti powders in N2,the action energy and the preexponential constant of the rapid weight gain stage of nano Ti powders are greater than the slow weight gain stage;the action energy and the preexponential constant of micro Ti powders with micro and nano TiO2 are greater than those of nano Ti powders,the action energy and the preexponential constant of micro and nano Ti powders with nano TiO2 are greater than those of micro and nano Ti powders with micro TiO2,the action energy and the preexponential constant of micro and nano Ti powders with micro and nano TiO2 increase with the increasing of the qualitative proportion of micro-nano TiO2,when the qualitative proportion of micro-nano TiO2 in micro and nano Ti powders reaches 70%,the activation energy and the preexponential constant of sample are maximum.