Molybdenum-on-chromium dual coating on steel

Molybdenum and chromium coatings were deposited on AISI 4130 steel using the Laser Induced Surface Improvement¹ (LISI™) process. In this process a mixture of precursor material is pre-placed on the substrate and then laser melted, resulting in the formation of a thin surface layer of alloy on the underlying material. First, a chromium coating was deposited on steel using the Cr-CrB₂ eutectic composition, and subsequently a molybdenum coating using the Mo-MoB eutectic composition was deposited on the chromium layer. Both the coatings have been individually characterized and compared using scanning electron microscope, energy dispersive spectrometry, Vicker’s hardness, X-ray diffraction, wear and erosion. The chromium layer exhibited superior erosion resistance (ASTM G76) while the molybdenum-on-chromium coating performed better in sliding wear (ASTM G77).