Investigations of the effects of DMF addition on LaMgAl 11 O 19 formation and its hot corrosion studies for environmental and thermal barrier applications

Abstract Yttria-stabilized zirconia (YSZ) has been widely used as an environmental and thermal barrier coating material. However, above 1200 °C, its thermo-physical properties degrade because of undesirable microstructural and phase modifications. On the other hand, rare-earth hexaaluminates, having magnetoplumbite structure, exhibit high-temperature phase stability and it possess excellent thermo-physical properties at temperatures above 1200 °C. This work highlights the development of lanthanum magnesium hexaaluminate (LaMgAl 11 O 19 ) ETBC material via wet-chemistry route, the effects on its crystal growth as a result of N , N -dimethylformamide (DMF) organic addition, and its hot corrosion studies. The as-synthesized doped DMF xerogel powders were calcined at 1100 °C–1400 °C, subjected to x-ray diffraction (XRD) and scanning electron microscopy (SEM) for their structural and morphological characterization. The average crystallite size of LMA decreased up to 14% (with addition of DMF) at the tested temperatures as confirmed by XRD. Whereas, SEM micrographs confirmed the platelet like microstructure of LMA powder. Hot corrosion studies at 700 °C, 800 °C and 900 °C for 5 h have revealed the degradation mechanism of LMA in V 2 O 5 environment. At 700 °C, AlVO 4 , and at 800 °C, LaVO 4 , MgAl 2 O 4 and AlVO 4 , whereas at 900 °C, α-Al 2 O 3 , MgAl 2 O 4 & LaVO 4 were confirmed as the main corrosion products.