Effect of synthesis technique on developing lanthanum magnesium hexaluminate powders as an alternative for thermal barrier coating

ABSTRACT Citric acid sol-gel technique and solid-state reaction method were used for synthesizing high purity lanthanum magnesium hexaluminate powders. The samples were calcined at 1150°C, 1250°C, and 1350°C to understand the effect of synthesis temperature on the L a M g A l 11 O 19 ( L M A ) samples. The collective effect of the synthesis technique and the synthesis temperature on developing lanthanum magnesium hexaluminate powders were analyzed using XRD, FTIR, SEM, TGA-DSC, and Particle analyzer. LMA powders obtained through sol-gel techniques showed better uniformity and pure LMA phase, while the ball milling method displayed traces of intermediate phases. The synthesized powders in the crystallite size of 150 nm and 280 nm were obtained through the sol-gel and ball milling technique, respectively. Citric acid sol-gel technique aided in the early onset of phase formation and the required closely packed platelet formation with a particle size of around 150 nm with good uniformity.