Crystallization mechanism of plasma-sprayed LaMgAl11O19 coating.

• The crystallization of amorphous LMA occurred at 900 and 1170 °C, respectively. • A novel crystallization mechanism on the amorphous LMA was proposed. • Crystallization kinetic of the amorphous LMA was studied. Amorphous phase is often detected in the plasma-sprayed LaMgAl 11 O 19 (LMA) coating, the crystallization of which can cause the volume reduction of the coating, resulting in the failure of the coating. However, it is still not clear for the crystallization mechanism of the amorphous phase. In this paper, the coating samples were deposited using atmospheric plasma spraying. Adequate evidence showed that the crystallization of amorphous LMA occurred in two stages at about 900 and 1170 °C, respectively, by studying the phase transition of Al 2 O 3 and the synthesis process of LMA. A novel crystallization mechanism on the amorphous LMA coating was also proposed. Results showed that highly charged La3+ in LMA magnetoplumbite structure controls the crystallization rate. The higher the La content in the composition the harder the crystallization occurs. [ABSTRACT FROM AUTHOR]