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Influence of Ln 3+ and B 3+ Ions Co‐Substitution on Thermophysical Properties of LnMB 11 O 19 ‐type Magnetoplumbite LaMgAl 11 O 19 for Advanced Thermal Barrier Coatings
Author(s) -
Haoran Lu,
ChangAn Wang,
Chenguang Zhang
Publication year - 2013
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12290
Subject(s) - materials science , analytical chemistry (journal) , raman spectroscopy , mineralogy , crystallography , chemistry , chromatography , optics , physics
Lanthanum hexaaluminate is a promising competitor to establish yttria partially stabilized zirconia as a thermal barrier coating material for Ni ‐based superalloy due to its relative low intrinsic thermal conductivity and low sinterability at temperatures exceeding 1100°C. Sr 2+ and Ti 4+ were selected as two dopants to partially substitute the La 3+ and Al 3+ in LaMgAl 11 O 19 , respectively. The variation in thermal conductivity with Sr 2+ and Ti 4+ fractions was analyzed based on structure information provided by X‐ray diffraction and Raman spectroscopy. The average crystal size of LaMgAl 11 O 19 sintered at 1600°C for 10 min by spark plasma sintering is in nanoscale. The fully dense La 1− x Sr x MgAl 11− x Ti x O 19 solid solution showed a minimum thermal conductivity value (λ = 1.12 W/(m K) −1 , T = 1273 K) at the composition of La 0.5 Sr 0.5 MgAl 10.5 Ti 0.5 O 19 ,which possibly reduces from the enhanced phonon scattering due to mass and strain fluctuations at the Ln 3+ and B 3+ sites.