Microstructure and oxidation resistance of a plasma sprayed Mo–Si–B multiphase alloy coating

A multiphase Mo–Si–B alloy coating can be successfully deposited onto the Mo–ZrC composite using a low pressure plasma spraying method. Microstructure of the plasma sprayed Mo–Si–B coating consists of Mo5Si3, Mo3Si and Mo5SiB2 phases, which are the same constituents as Mo–Si–B alloy powder. Nanostructure is formed in the Mo–Si–B coating with the eutectic composition owing to the rapid quenching effect by plasma spraying. The oxidation behavior of the Mo–Si–B coating shows rapid mass loss followed by slow mass gain at 1673 K in Ar–20%O2. Dense and adherent borosilicate glass formation passivates the coating against further oxidation at 1673 K.