Effect of In situ Synthesis on the Microstructure, Corrosion, and Wear Resistance of Fe-Based Amorphous-Nanocrystalline Coatings

Fe-based amorphous-nanocrystalline coating with in situ synthesized particles was prepared on the surface of Q235 steel by laser cladding technology. The uniform and dense Fe-based composite coating of metallurgical bonding was obtained without obvious crack. The microstructure, composition distribution, corrosion resistance, hardness, and wear resistance of the coatings were characterized. In situ synthesized products including Cr23C6, Al2O3, borides, and carbides of Zr coexist in the coating. For 15% three-component powder addition, laser power of 1500 W yields the finest grain. With the laser power being constant at 1500 W, the corrosion resistance of the coatings rises first and then falls with the increase in the three-component powder. The coating with 15% three-component powder shows the lowest corrosion current density, highest polarization resistance, and largest radius of capacitive arc indicating the best corrosion resistance. The hardness and wear resistance results show that the highest microhardness and best corrosion resistance occur at the 15% three-component powder addition ascribing to the better effect of the in situ formed reinforcing phase. The action mechanism of the in situ synthesized reinforcing phase was discussed. The work shows practical value for the fabrication of corrosion-resistant coatings.