Facile synthesis and electrochemical properties of a novel Ni-B/TiC composite coating via ultrasonic-assisted electrodeposition.

A novel Ni-B/TiC composite coating was synthesized by ultrasonic-assisted direct current electrodeposition. Ultrasonic technology was adopted to prevent the agglomeration of nanoparticle, improve the structure and corrosion resistance, using an ultrasonic bath at frequency 40 KHz and acoustic power 300 W. The influences of current density and deposition time on its structure and electrochemical behaviors were studied. Under ultrasonic dispersion, the composite coatings are smooth, compact with protrusion structure sparsely distributed on it. The average roughness (Sa) was about 13.6-26.1 nm. The crystallite size is 10-21 nm. The preferred orientation is Ni (1 1 1) texture. EIS results indicated that the corrosion resistance was greatly improved by ultrasonic-assisted method. The corrosion mechanism is consistent with one-time constant EEC model of Rs(CPEdlRct). With the increase of immersion time, the Rct of the composite coating often first increased and then decreased. Under ultrasonic, current density 2 A dm-2 and deposition time 20 min were the appropriate parameters for the optimal corrosion resistance and excellent long-term electrochemical stability in 3.5 wt% NaCl corrosive solution. This coating shows good application prospect for corrosion protection in aggressive environment.