掺杂La_(2)O_(3)的Al/CuO铝热剂的反应特性

Reactive Characteristics of La_(2)O_(3)-Doped Al/CuO Thermite

为了研究La_(2)O_(3)对Al/CuO铝热剂反应特性的影响,采用机械混合法制备了不同氧平衡状态,即当量比(φ)分别为1.0,1.4和1.8下的Al/CuO铝热剂,并分别掺杂2%,5%,10%,20%和30%的La_(2)O_(3)。利用扫描电子显微镜(SEM)、X⁃射线能谱仪(EDS)、X⁃射线衍射仪(XRD)和差示扫描量热仪(DSC)分别对未掺杂和掺杂La_(2)O_(3)的Al/CuO铝热剂的微观形貌、元素种类、物相以及放热过程进行了研究,采用燃烧管实验、T⁃jump快速升温点火实验和密闭爆发器实验对其燃烧特性和产气性能进行了对比分析。结果表明,零氧平衡状态(φ=1.4)下,掺杂La_(2)O_(3)的Al/CuO铝热剂发生铝热反应的起始温度和峰值温度明显低于未掺杂La_(2)O_(3)的Al/CuO铝热剂;掺杂2%La_(2)O_(3)的Al/CuO铝热剂放热量为1772 J·g^(-1),较未掺杂La_(2)O_(3)的Al/CuO铝热剂放热量1540 J·g^(-1)增长了15.1%。正氧平衡状态(φ=1.0)下,掺杂2%La_(2)O_(3)的Al/CuO铝热剂燃速为90.8 m·s^(-1),比未掺杂La_(2)O_(3)的Al/CuO铝热剂燃速61.9 m·s^(-1)增长了46.7%。Al/CuO铝热剂的点火温度随La_(2)O_(3)掺杂量的增加呈现上升的趋势。掺杂La_(2)O_(3)对Al/CuO铝热剂的产气性能有不同程度的改善,其中,正氧平衡状态(φ=1.0)和负氧平衡状态(φ=1.8)下,峰值压力较未掺杂时分别上升了34.5%和13.7%,对φ=1.4的铝热剂,产气性能改善不明显。火焰传播结果显示,La_(2)O_(3)的掺杂会改变Al/CuO铝热剂的火焰传播模式,随着掺杂量的增加,Al/CuO铝热剂燃烧状态由爆燃变为缓燃,能够作为一种燃烧速度和能量释放速率的控制手段。

To investigate the effect of doping La_(2)O_(3)on the reactive characteristics of Al/CuO thermite,Al/CuO thermites with equivalent ratio(φ)of 1.0,1.4 and 1.8 doped with different content of La_(2)O_(3)were prepared by mechanical mixing method.The samples were characterized by scanning electron microscope(SEM),X⁃energy dispersive spectrometer(EDS),X⁃ray diffractome⁃ter(XRD)and differential scanning calorimetry(DSC),respectively.Combustion and gas production performances were evaluat⁃ed by using flame propagation experiment,T⁃jump ignition and pressure cell test.The results show that the initiation reaction temperature and the peak temperature for the Al/CuO thermite doped with La_(2)O_(3)were significantly lower than those of Al/CuO thermite without doping La_(2)O_(3)atφ=1.4.The heat release of Al/CuO thermite was 1772 J·g^(-1)when 2%La_(2)O_(3)was doped,which increased by 15.1%compared with that of the undoped Al/CuO thermite(~1540 J·g^(-1)).The combustion rate of Al/CuO thermite with 2%La_(2)O_(3)was 90.8 m·s^(-1)atφ=1.0,which was 46.7%higher than that of the undoped Al/CuO thermite(61.9 m·s^(-1)).The ignition temperature of Al/CuO thermite was also raised when La_(2)O_(3)was added.It is suggested that La_(2)O_(3)improved the gas pro⁃duction performance of Al/CuO thermite to varying degrees.The peak pressure of Al/CuO thermite formulated atφ=1.0 andφ=1.8 increased by 34.5%and 13.7%,respectively.The effect of equivalent ratio atφ=1.4 on peak pressure of Al/CuO thermite was unclear.The combustion results indicated that doping La_(2)O_(3)will alter the flame propagation mode of Al/CuO thermite.The combustion state was observed to be changed from deflagration to slow combustion with the increase of La_(2)O_(3).The inclusion of La_(2)O_(3)in Al/CuO thermite is suggested to be used as a means to control the propagation velocity and energy release.