不同溶剂置换法制备纳米氧化镁粉体的研究

Research on preparing nanometer magnesia powder by different solvent-replacement methods

以氯化镁与尿素为原料,采用均匀沉淀法得到氢氧化镁沉淀,经水洗、水洗+醇洗、水洗+正丁醇共沸蒸馏3种溶剂置换后,再用烘箱干燥得到厚度仅为几纳米的片状氢氧化镁粉体,氢氧化镁粉体经高温煅烧得到纳米氧化镁粉体。X-射线衍射、红外光谱和透射电子显微镜3种方法表征结果表明,纳米氧化镁粉体的粒径约为20～30nm,其团聚程度以及晶粒大小与溶剂置换的方法有关,团聚程度和晶粒大小由大到小的顺序为水洗、水洗+醇洗、水洗+正丁醇共沸蒸馏。此外,还用毛细管理论和氢键理论讨论了纳米粉体团聚的原因。

Taking magnesium chlorideand urea as raw material,magnesium hydroxidesediment is prepared by homogeneous precipitationprocess.Thesediment has been treated by waterwashing, waterwashing+alcoholwashing,and water washing+ butyl alcoholazeotropic distillation,then,the flaky magnesium hydroxide with several nanometer thickness is obtained after dried in the cabinet.Nanoscale magnesium oxide is obtained after magnesium hydroxideis calcinated at high temperature. Nanoscale magnesium oxide or magnesium hydroxideare charactered byX-ray diffraction(XRD),transmission electron microscope (TEM) and infrared spectrum(FI/IR).The result indicates that particle size of magnesia oxide is about 20～30 nm,the granularityand agglomeration degree of nanoparticle magnesium oxide are relevantwith solvent-replacement method.The agglomeration degree andgranularityare mitigated by the following order: water-washing, waterwashing+ alcohol washing, water washing+butyl alcoholazeotropic distillation.The reason of agglomeration is discussed by both Capillary pressure theoryand Hydrogen bond theory.