添加剂Mg对燃烧合成AlB_2-Al_2O_3复合粉体物相组成的影响

Effect of Mg Additive on the Phase Composition of AlB_2-Al_2O_3 Composite Powders Prepared by Combustion Synthesis

以Al和B2O3为原料采用燃烧合成方法制备了AlB2-Al2O3复合粉体,研究了Mg的添加量对燃烧反应产物物相组成的影响。用温度-时间记录仪测定了反应的燃烧温度,并计算了燃烧波速度;用XRD研究合成产物的物相组成;用差示扫描量热-热重研究了原料混合粉在加热过程中的反应过程;用场发射扫描电子显微镜、能谱研究合成产物的显微形貌。结果表明,随着Mg的增加,Al-B2O3-Mg体系燃烧温度降低,燃烧波速度加快;产物物相有Al2O3、AlB2、Mg Al2O4固溶体及残余的Al,随着Mg添加量的升高,Mg Al2O4固溶体增加,Al2O3和Al降低,AlB2先增加后减少,在添加6wt%Mg时到达最高值;DSC-TGA结果显示添加6wt.%Mg时燃烧合成反应的引燃温度为1182 K;扫描结果显示Al2O3为粒径2~4μm的球状颗粒,AlB2为粒径5~10μm的颗粒,MgAl2O4固溶体为不规则连续基体。

The AlB2-Al2O3 composite powders were prepared using Al and B2O3 as raw materials by combustion synthesis（ CS）. The effects of Mg addition amounts on the phase of product were studied. The combustion temperature was recorded by temperature-time recorder,and the combustion wave velocity was calculated. The phases of product were characterized by XRD. The changes of raw materials in the heating process were studied by DSC-TGA. The microscopic morphology of products was characterized by FESEM and EDS. The results showed that the combustion temperature of Al-B2O3-Mg system decreased with increasing amount of Mg,while its combustion wave velocity increased. The synthesized products of Al-B2O3-Mg system contain Al2O3,AlB2,Mg Al2O4 solid solution and Al. With increasing of Mg,the content of Mg Al2O4 solid solution increases while the contents of Al2O3 and Al decreased,and the content of AlB2 reached its highest value when adding 6wt% Mg; DSC-TGA show that the ignition temperature is 1182 K when adding 6wt. % Mg.SEM show that Al2O3 is spherical particles with the size of 2 ~ 4 μm,and AlB2 is hexagonal-shaped particles with the size of 5 ~ 10 μm,being embedded in continuous unshaped matrix of MgAl2O4 solid solution.