Bidirectional pulsed electrodeposition of Ni-Cr alloy coating process on NdFeB magnets surfaces and corrosion resistance
Neodymium-iron-boron(NdFeB)magnets are widely used in new energy vehicles,wind power generation and other fields.However,the magnets are easily corroded,which is detrimental to the stability of the applied products.In this study,bi-directional pulse electrodeposition technology was employed to investigate the effects of different pulse parameters(pH value,current density,duty cycle of the forward pulse,and Cr salt concentration)on the corrosion resistance and microstructure of Ni-based coatings.The results showed that under the conditions of pH=4.5,current density of 0.20 A/cm²,forward duty cycle of 60%,and Cr salt concentration of 25 g/L,the prepared Ni-Cr alloy coating had excellent surface quality and good corrosion resistance.Its Rct value significantly increased to 36 990 Ω∙cm²,the self-corrosion potential dropped to ‒707 mV,and the corrosion current density was only 1.04×10‒8 A/cm².This study provides an effective method and theoretical basis for enhancing the corrosion resistance of NdFeB magnets.
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