Improvement on thermophysical and mechanincal properties of LaMgAl11O19 magnetoplumbite by Nd2O3 and Sc2O3 co-doping. Issue 20 (15th October 2021)

• Record Type: Journal Article
• Authors: Lu, Xiangrong; Yuan, Jieyan; Xu, Mingyi; Hu, Qing; Huang, Jingqi; Deng, Longhui; Jiang, Jianing; Dong, Shujuan; Liu, Li; Qin, Lu; Cao, Xueqiang
• Is Part Of: Ceramics international. Volume 47:Issue 20(2021)
• Page Start: 28892
• Page End: 28903
• Publication Date: 2021-10-15
• Subjects: Thermal barrier coatings -- LaMgAl11O19 -- Thermal conductivity -- Thermal expansion -- Mechanical properties; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.07.050
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: LaMgAl11 O19 -type magnetoplumbite holds great promise to be used above 1300 °C as thermal barrier coatings (TBCs), but its practical application has been restricted because of inferior thermophysical properties. Herein, we focus on optimizing the thermophysical properties of LaMgAl11 O19 by simultaneously substituting La 3+ and Al 3+ ions with Nd 3+ and Sc 3+ ions, respectively. Results show that the effects of co-substitution on reducing thermal conductivity are pronounced. The thermal conductivities of La1- x Nd x MgAl11- x Sc x O19 ( x = 0, 0.1, 0.2, 0.3) ceramics decrease progressively with dopant concentration and a lowest thermal conductivity of 2.04 W/(m·K) is achieved with x = 0.3 at 1000 °C, which is a value superior to pure LMA and even lower than YSZ. The mechanisms behind the lowered thermal conductivity are investigated. Increase of the thermal expansion coefficient is also realized (8.53 × 10 −6 K −1 for pure LMA, 9.07 × 10 −6 K −1 for x = 0.3, 1300 °C). Most importantly, Nd 3+ and Sc 3+ combination doping indeed facilitates mechanical properties of La1- x Nd x MgAl11- x Sc x O19 solid solutions as well. It should be noted that Sc 3+ doping at Al 3+ site plays more effective role in improving thermal properties than Nd 3+ does at La 3+ site. This work provides a path to simultaneously integrate low thermal conductivity, good phase stability, moderate thermal expansion behavior and excellent mechanical properties on LMA for the next generation TBCs.