MgAl_2O_4粉体的低温燃烧合成与烧结性能

Low-temperature Combustion Synthesis and Sintering Properties of MgAl_2O_4 Powders

以尿素、甘氨酸和淀粉为燃烧剂,用低温燃烧法合成了MgAl2O4纳米粉体,并研究硝酸铵(氧化剂)外加量对燃烧过程、粉体特性及烧结活性的影响,分别用SEM、XRD对MgAl2O4粉体的显微结构和物相组成进行了表征。实验结果表明:随着前驱体中硝酸铵加入量的增大,燃烧方式从无焰燃烧转变为有焰燃烧,且有焰燃烧时间显著增加,燃烧产物的烧失量大幅度减小,MgAl2O4纳米晶的粒径明显增大,而粉体的烧结活性则先升高后降低。当硝酸铵和(硝酸铝+硝酸镁)的物质的量比为0.04∶0.15时,用低温燃烧法合成的MgAl2O4粉体的烧结活性较高,制备的陶瓷材料的相对密度达到了98%。

Nano-sized MgAl2O4 powders were synthesized via a low-temperature combustion process using urea,glycine and starch as fuel,and the effects of NH4NO3（as an oxidizer） addition on combustion process,characteristics and sinterability of MgAl2O4 powders were also investigated.The microstructure and phase composition of MgAl2O4 powders were characterized by XRD and SEM,respectively.The experimental results reveal that as the NH4NO3 addition increasing,the combustion type transforms from flamless combustion to flaming combustion,the flaming combustion time increases significantly,ignition loss of the combustion products decreases remarkably,and the crystallite size of MgAl2O4 powders enlarges markedly.On the other hand,the sinterability of MgAl2O4 powders firstly increases significantly and then decreases as the NH4NO3 addition increasing.The MgAl2O4 powder synthesized from the precursor with the NH4NO3/（Al（NO3）3＋Mg（NO3）2） molar ratio of 0.04/0.15 exhibits higher sinterability as compared with other powders and the ceramics from the powder has a relative density as high as 98%.