Abstract:

Ni-P alloy was deposited on the surface of birch veneer by using ultrasound-assisted electroless plating method. Electromagnetic shielding effectivness(ESE)of plated birch veneer was used as index to discuss plating temperature and time under 100 W ultrasonic irradiation, and compare the effect of ultrasound power of 0, 100 and 250 W. At the same time, the relationships of microstructure of the layer, surface morphology and P content to ultrasound power were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM)and energy dispersion spectrum(EDS). Bonding strength of the layers deposited under 0 and 100 W ultrasonic irradiation was measured by vertical pulling method. The results show that the effect of ultrasonic irradiation is more obvious when plating temperature is lower. The ESE plated birch veneer under 62 ℃ for 20 min under 100 W ultrasonic irradiation is up to 60 dB in the frequencies from 9 kHz to 1.5 GHz. Ultrasound-assisted electroless plating needs lower temperature and less time than conventional electroless plating. Ultrasonic irradiation makes P content increase and surface morphology un-uniform. However, the layers deposited under ultrasonic irradiation are still crystalline. High bonding strength exists between the layer and wood surface no matter ultrasound-assisted or not. Excessively high power ultrasonic irradiation is disadvantageous for electroless plating. 100 W ultrasonic irradiation is feasible after comprehensive analysis.

Key words: ultrasound-assisted, birch veneer, electroless plating, Ni-P alloy, electromagnetic shielding effectivness