In-situ preparation and oxidation behavior of MgAl2O4-containing ceramic/metal composite coatings via hot dipping

A ceramic/metal composite coating containing MgAl2O4 was in-situ synthesized on TC4 alloy (comprising Ti6Al-4V) utilizing a hot dipping technique. This research delineates the three-tiered architecture of the composite coating, characterized by an external oxide layer composed of MgAl2O4-MgO-Al2O3, an intermediate layer featuring a TiAl2-Al2O3 amalgamation, and a intermetallic layer enriched with Ti-Al compounds. It was deciphered from comparative analysis that following a 150-h oxidation tenure, a transformation in the coating's morphology occurred, giving rise to a MgAl2O4-TiO2 outer oxide layer and a preserved Ti-Al intermetallic inner layer. A critical revelation was the emergence of a dense, continuous MgAl2O4-TiO2 layer proximal to Ti-Al intermetallic layer within the oxide stratum. This fortifying layer played a pivotal role in thwarting the further diffusion of O and Ti atoms, thus endowing the substrate with remarkable stability (>= 500 h) at 850 degrees C in air.