A 30kW pulsed and DC power was used for the experiments. The treatment was conducted by
adopting constant current mode, and the fixed electrical parameters were frequency 600Hz, duty circle 0.2,
cathode-anode current density ratio 1.0 and treatment time 20min. The electrolyte was prepared using the
solution of silicate-based salt and “Ostrich” brand carbon ink, KOH (2g/L) and NaF (2g/L) served as the
auxiliary coating-forming additives; all the electrolyte were prepared by using analytical grade reagents
and deionized water. Using L16(45
) standard orthogonal form, factors and levels design are shown in