جستجوی مقالات مرتبط با کلیدواژه « Ultrasound wave frequency » در نشریات گروه « علوم پایه »

The nickel-phosphorus (Ni-P) and nickel-phosphorus-nanodiamond (Ni-P-ND) coatings were deposited on mild steel via electroless plating without ultrasound and under ultrasonic agitation with different frequencies of 25, 50, 75, 100, and 150 kHz. The as-prepared coatings were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The corrosion performance of the fabricated layers was evaluated in 3.5 wt% NaCl solution by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. Results of the corrosion tests demonstrated that deposition under ultrasonic power provided coatings with higher stability in the corrosive environment. The corrosion rate decreased with increasing ultrasound frequency from 25 to 75 kHz but increased with further increase in frequency. This introduced 75 kHz as the optimum ultrasound frequency for electroless plating of Ni-P. It was also observed that the corrosion resistance of the proposed coating was improved through the incorporation of 40 ppm nanodiamond into the Ni-P matrix.

In this paper, the precipitation of nickel-phosphorous (Ni-P) electroless coatings including Al2O3 nanoparticles (Ni-P-NA) using ultrasound waves on mild steel has been studied. Deposition process occurred in a lactic plating bath by the autocatalytic method using an ultrasound probe. The effect of radiation frequency on the properties of coatings was investigated, and the optimum frequency was determined. The obtained samples were evaluated for their corrosion resistance, surface morphology, and hardness by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and scanning electron microscopy (SEM). The results showed that ultrasound waves caused an improvement in the corrosion resistance and uniformity of the coatings. Furthermore, five different wave frequencies applied during deposition disclosed the remarkable impact of frequency on the smoothness and corrosion resistance of the resultant coatings. On this basis, the Nyquist diagrams showed that the corrosion resistance of the prepared Ni-P-NA coating at an optimum frequency of 75 kHz was 2.59 kΩ·cm2. This value was about 2.5 times higher than the value obtained for the Ni-P-NA coating deposited without ultrasound power.