Superior anti-oxidation layer induced by PVA-boehmite sol-gel film on AISI304 steel

The superior anti-oxidation layer induced by the PVA-boehmite sol-gel film on the AISI304 steel during the cyclic oxidation is investigated in this work. The moderate PVA addition in the boehmite sol conduces to increase the film thickness and is beneficial to the adhesion between the film and the substrate. The presence of the PVA-boehmite film leads to a significant reduction in mass gain during the high-temperature cyclic oxidation at 800°C, demonstrating the enhanced oxidation resistance. The generated oxide layer induced by the PVA-boehmite film presents as a thin, compact, and continuous layer without spalling, offering sustainable protection against oxidation etching. The PVA-boehmite film promotes the preferential formation of the corundum (Al, Cr)2O3 phase rather than the detrimental hematite Fe2O3 phase during the oxidation procedure, which facilitates the development of the above compact oxide layer. Finally, the superior anti-oxidation oxide layer is characterized as a novel dual-layer structure: the outer spinel MnCr2O4 layer and the inner corundum (Al, Cr)2O3 layer, effectively delaying the oxidation process.