Abstract
In the present study, an electro-spark deposition method was applied to obtain a corrosion resistant FeAl-based layer onto the steel surface. In this context, firstly the pulse parameters of deposition process were optimized and among all the parameters, 200 A and 50 μs were determined as the best ones. Then, micro-arc oxidation technique was performed to enhance tribological properties of the FeAl-coated steel samples in the electrolyte solution which consisted of Na₃PO₄ and NaAlO₂. The coated samples were characterized by SEM/EDX and XRD examinations. The results showed that the duplex coating was composed of Al₂O₃ and FeAl₂ phases while FeAl, Fe₂Al₅, and Fe₃Al phases were present in the ESD coating. Mechanical properties of duplex coatings on the steel substrate were significantly improved, and so the microhardness of micro-arc oxidation and electro-spark deposition coatings was about 4 and 5 times of the steel substrate microhardness, respectively. Moreover, the corrosion resistance of the coatings was determined as well. Its value for the micro-arc oxidation and electro-spark deposition coating was about 40 and 20 % better than that for the substrate steel, respectively.

Key words
electro-spark deposition, micro-arc oxidation, duplex coating, Fe-Al intermetallic

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