Spacecraft components are exposed to environments like wide-ranging temperatures, radiation and atomic oxygen which causes material degradation. Temperature stability, damage tolerance and strength are essential for the intact functioning of the components. Coatings are one among the effective thermal control processes. Materials like MAB (ternary transition metal boride) phase alloys, formed by interleaving layer(s) of III-A or VI-A element between metal borides (MB) possess good wear, corrosion and thermal shock resistance. They exhibit radiation induced cracking resistance by defect annealing and also involve better oxidation resistance by forming self-healing alumina films. They can be proposed to use in aerospace applications like solar absorbers, fuel cladding and semiconductors. Though MAB phase alloys can be coated using high velocity oxy fuel coating, plasma spraying and magnetron sputtering, they have not been explored widely. High velocity oxy-fuel coatings have low deposition efficiency while plasma spraying provides high deposition efficiency with good adhesion strength. Also, atmospheric plasma spraying of Fe2AlB2 is a novel coating system which has not been reported so far. Hence, in the present investigation, Fe2AlB2 will be synthesized and subjected to atmospheric plasma spraying to investigate their thermal and optical properties.

This research work focuses on synthesizing Fe2AlB2 or MoAlB alloys through powder metallurgical route and produce plasma sprayed coatings. Elemental precursors are mechanically milled and sintered to produce the ternary MAB phase alloys. The synthesizing parameters are optimised after observing their thermal and optical behaviour. Solar absorptance values helps in understanding the thermal absorption behaviour in harsh space environments. Better absorption and reflection properties were observed in Fe2AlB2 alloys which helps in thermal control of the spacecraft components and thereby increase their service life. Bulk powder synthesises would be carried out to obtain necessitate powders for atmospheric plasma spraying. Improved coating performances are envisioned through spraying parameter optimization. Lastly, microstructural, mechanical and thermo-optical properties are to be explored for their corresponding improvements in thermal control and radiation cracking resistance.

Keywords: MAB phase alloys, Radiation damage, Thermal control, Plasma Spraying