无氰电镀液中超声电沉积耐腐蚀纳米晶铜镀层

Corrosion-Resistant Nanocrystalline Cu Coating by Ultrasonic Electrodeposition in Cyanide-Free Electrolyte

通过超声辅助电沉积法,在无氰络合电镀液中以高阴极电流密度在钕铁硼磁体上电沉积获得纳米晶铜防护镀层,研究了不同超声波频率下的镀层形貌、晶粒尺寸、显微硬度和耐腐蚀性能。结果表明,随着超声波频率的增加,络合电镀液体系的铜电沉积有效阴极电流密度显著增加,相应的阴极电流效率也提高,从而获得致密的纳米晶铜镀层。在阴极电流密度为4.0 A·dm^(−2)和超声波频率为40 kHz的条件下,能够获得平均晶粒尺寸为18.8 nm的铜镀层。超声辅助电沉积法还能促进烧结钕铁硼基体盲孔内的铜沉积,从而改善基体与镀层之间的结合力。在同样的镀层厚度下,烧结钕铁硼表面所沉积镀层的耐腐蚀性随超声波频率的提高而优化。

The nanocrystalline Cu protective coating was obtained on the Nd-Fe-B magnet matrix in the cyanide-free electrolyte by the ultrasonic-assisted electrodeposition under high cathodic current density.The coating morphology,crystallite size,microhardness,and corrosion resistance of the Cu coatings were analyzed under different ultrasonic frequencies.Results show that with increasing the ultrasonic frequency,the effective cathodic current density of Cu electrodeposition in the complex electroplating solution system is increased remarkably,and the corresponding current efficiency is enhanced,thereby achieving the dense nanocrystalline Cu coating.Under the condition of the cathodic current density of 4.0 A·dm^(−2) and frequency of 40 kHz,the Cu coating with the crystallite of 18.8 nm in size can be obtained.The bonding strength between the Cu coating and sintered Nd-Fe-B matrix is improved via ultrasonicassisted electrodeposition which promotes the electrodeposition in the blind holes of Nd-Fe-B matrix.The corrosion resistance of Cucoated Nd-Fe-B materials with the same coating thickness is improved gradually with increasing the ultrasonic frequency.