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采用化学镀方法在烧结钕铁硼表面制备了Ni-P/Ni-Co-P合金镀层,研究了Ni-P预镀层与多孔基材界面结合特征、不同金属离子浓度比[Co2+]/[Ni2++Co2+]对镀层成分、组织结构及表面形貌的影响。结果表明:Ni-P预镀层与钕铁硼基材呈犬牙交错,增加了界面的有效结合面积,提高了结合强度,说明预镀层溶液具备较强的深镀能力;Ni-P/Ni-Co-P镀层间结合紧密,两者具有优异的相容性和相似的结构特征。Ni-Co-P镀层表面由不同尺寸胞状物组成,组织致密,孔隙率几乎为零;随金属离子浓度比值的增加,镀层表面颜色由暗银白色变为亮银白色,镀层中Ni和P含量降低,Co含量增加,表明镀层成分与镀液中主盐金属离子的浓度密切相关。XRD分析结果表明,随金属离子浓度比的增加,镀层呈现由非晶结构向微晶结构转变的趋势。在金属离子浓度比为0.3~0.5范围内,镀层表面胞块尺寸随金属离子浓度比的增加而减小;当金属离子浓度比值增至0.6时,镀层表面胞块尺寸变大,且呈微晶形态,说明在0.5~0.6之间存在一临界值,小于此值,镀层组织结构为细小的非晶态胞块形貌,大于此值,镀层则由非晶态结构开始发生向微晶组织结构转变。
Ni-P / Ni-Co-P alloy coating was prepared on the surface of sintered NdFeB by electroless plating method. The interface bonding characteristics between Ni-P pre-coating and porous substrate were studied. The effect of different metal ion concentration ratio [Co2 +] / [Ni2 ++ Co2 +] on the coating composition, structure and surface morphology. The results show that the Ni-P pre-coating and the Nd-Fe-B substrate cross intertwined, increasing the effective bonding area of the interface and enhancing the bonding strength, indicating that the pre-plating solution has strong deep plating capability; Ni-P / Ni- P-plated combination between the close, both have excellent compatibility and similar structural features. The surface of Ni-Co-P coating is composed of cells of different sizes with compact structure and almost zero porosity. The color of coating surface changes from dark silver white to bright silver white as the metal ion concentration ratio increases. The Ni and P contents Decreased, Co content increased, indicating that the composition of the plating bath and the main salt metal ion concentration is closely related. The results of XRD showed that with the increase of the metal ion concentration ratio, the coating showed the transition from amorphous structure to microcrystalline structure. In the range of 0.3 ~ 0.5, the size of the cell surface decreases with the increase of metal ion concentration ratio. When the metal ion concentration ratio increases to 0.6, Morphology, indicating that there is a critical value between 0.5 and 0.6, less than this value, the microstructure of the coating is a fine amorphous cell morphology, greater than this value, the coating from the amorphous structure began to occur to the microstructure change.