共沉淀法制备镁基六铝酸镧粉体的性能研究  

Performance Research of Magnesium Base Lanthanum Hexaaluminate Prepared by Co-Precipitation

作　　者：李(王莹) 孙超[1] 宫骏[1] LI Ying;SUN Chao;GONG Jun(Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院金属研究所,沈阳110016 [2]中国科学院大学,北京100049

出　　处：《金属学报》2019年第5期657-663,共7页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.51301180~~

摘　　要：用共沉淀法,选取沉淀温度60℃,沉淀pH值11.5制备的镁基六铝酸镧前驱粉体,在1500℃煅烧5 h后制备出热障涂层陶瓷层材料LaMgAl_(11)O_(19)。采用XRD、TEM、SAED和XPS分析了反应产物的相结构、形貌、半峰全宽和谱强。结果表明,提高沉淀温度制备的前驱粉体磁铅石相生成效率提高;LaMgAl_(11)O_(19)晶体发育良好,晶粒呈六角片方状;前驱粉体煅烧温度在1500℃左右,La、Mg、Al、O 4种原子的电子结合能增大,动能减小,反应物趋于稳定;LaMgAl_(11)O_(19)晶胞结晶过程中先生成尖晶石层,后形成镜面层。生成纯磁铅石相粉体的过程中,LaAlO_3、MgAl_2O_4键的半峰宽度有增大,晶体结构无序度增加,有利于提高陶瓷层的抗烧结能力及热稳定性。Thermal barrier coatings are widely used on turbine blades to provide high temperature insulation,oxidation and corrosion protection.Thermal barrier coatings are composed of matrix,oxide layer,bonding layer and ceramic layer.The lanthanum magnesium hexaaluminate with magnetoplumbite structure have a high aspect ratio,large specific surface area and strong resistance to high temperature sintering,and it can be used as ceramic layer of thermal barrier coatings.In this work,the former powders of lanthanum magnesium hexaaluminate was prepared at synthesized temperature of 60 ℃,pH=11.5.Comparing with the conventional chemical co-preparation synthesis,the synthesized temperature was raised and the pH value for synthesizing was reduced,which resulted in improving production efficiency of former powders.And the lanthanum magnesium hexaaluminate powders for ceramic layer of thermal barrier coating was prepared after the precursor powders were calcinated at 1500 ℃ for 5 h.The phase structure of reaction products,morphology of the powders,full width at half maximum and spectral intensity were analyzed by XRD,SEM,TEM and XPS.The results showed that the magnetoplumbite structured formation generation was elevated much more efficiency if the former powders were precipitated at higher temperature.Since the bonding energy of La,Mg,Al and O atoms increased,the kinetic energy of electrons decreased,therefore,chemical composition of the reaction products were steady near1500 ℃.During the crystallization process of lanthanum magnesium hexaaluminate,the spinel layer was generated firstly and mirror layer was consequently produced.In the process of producing pure magnetoplumbite phase powders,the full width at half maximum of LaAlO3 formula and MgAl2O4 formula were increased and the activation energy of the crystal structure was higher than that before reaction,which was beneficial to improve anti-sintering performance and thermal stability of the ceramic coating.

关 键 词：磁铅石相 六铝酸镧 晶体结构 原子成键 

分 类 号：TG174.442[金属学及工艺—金属表面处理]