微纳米金属铁粉的燃烧特性试验研究

Experimental study of combustion characteristics of micron and nano iron powders

运用热重分析手段对微纳米尺度金属铁粉燃料的着火和燃烧特性进行了研究.通过不同微米、纳米尺度金属铁粉燃烧过程的热重试验,分析不同粒径金属铁粉的燃烧特性,计算不同微米、纳米尺度金属铁粉在空气中燃烧的着火点、最高燃烧温度和表观活化能.结果表明,30～110nm粒径范围的纳米尺度铁粉的平均着火温度为280℃左右,最高燃烧温度为750～950℃,表观活化能为20～30kJ/mol;2～5μm亚微米级铁粉着火点为380℃,最高燃烧温度为950～990℃,表观活化能为37kJ/mol;而40μm的微米级铁粉着火温度为600℃左右,最高燃烧温度达到1000℃,表观活化能为58kJ/mol.随着颗粒粒径从微米减小到纳米尺度,金属颗粒的比表面积迅速增大,造成TG/DTG曲线上最大增重梯度所对应的反应温度和最高燃烧温度均明显降低,燃烧着火点温度明显降低,表观活化能迅速减小,因此反应活性随粒径的减小迅速提高.

The ignition and combustion characteristics of micro-nano sized iron particle metal fuels were investigated by thermogravimetry.Based on thermogravimetric experimental results,the combustion characteristics of the iron particle metal fuels varied from micron to nano size were obtained and analyzed.Ignition temperatures as well as maximum combustion temperatures and apparent activation energies of the different sized iron particles burnning in air were calculated and determined.Results indicate that：the ignition temperature of 30～110nm sized iron particles is about 280℃,the maximum combustion temperature is 750～950℃and the activation energy is about 20～30kJ/mol;the ignition temperature of 2～5μm submicron sized iron particle is about 380℃ with maximum combustion temperature 950～990℃and activation energy 37kJ/mol;while the values of 40μm micron sized iron particles are 600℃,1 000℃,and 58 kJ/mol,respectively.With particle size decreasing from micron down to nano scale,surface area of the iron particles increases dramatically causing the obviously decreasing of temperature at maximum weight gradient in TG/DTG curves and final maximum combustion temperature.The ignition temperature and activation energy all drop apparently with the size changing of particles.Therefore,activities of the iron particle metal fuels can be greatly enhanced with decreasing of particle size.