氧化物颗粒增强 Ni-W-P / Nb2 O5 复合镀层制备及其耐腐蚀性能

目的对NdFeB磁性材料进行表面防护处理,改善其耐腐蚀性能。方法利用化学镀方法,在NdFeB基体材料表面制备氧化物颗粒增强的晶态和非晶态Ni-W-P/Nb2O5复合镀层,对镀层的组织形貌、元素组成分布及物相进行分析,并通过化学腐蚀失重法对耐腐蚀性能进行测试。结果当镀液中的次亚磷酸钠含量为20 g/L时,形成了晶态镀层;为35 g/L时,形成了非晶态镀层。晶态和非晶态Ni-W-P/Nb2O5镀层均由胞状突起组成,其中弥散分布着共沉积的Nb2O5颗粒。镀层样品的XRD图谱中没有出现与钕铁硼相关的衍射峰。对于制备的晶态和非晶态复合镀层,镀液中Nb2O5质量浓度由5 g/L增加到15 g/L时,化学腐蚀速率明显下降;Nb2O5质量浓度由15 g/L增加到20 g/L时,化学腐蚀速率的下降变得缓慢。结论利用化学镀可以在NdFeB磁性材料表面制备致密的Nb2O5增强Ni-W-P复合镀层,且随着Nb2O5含量的增加,复合镀层的耐腐蚀性能提高。

Preparation of Oxide Particles Enhanced Ni-W-P / Nb2O5 Composite Coatings by Electroless Plating and Its Corrosion Resistance

Objective To protect the surface of NdFeB permanent magnetic materials and improve its corrosion resistance. Methods The oxide particles enhanced crystalline and amorphous Ni-W-P/ Nb2O5 composite coatings were deposited on the NdFeB substrate using electroless plating, respectively. The microstructure, chemical elements distribution and the existed phases of the coatings were analyzed. The corrosion resistance of the composite coatings was also evaluated using weight loss experiments. Results The crystalline and amorphous composite coatings were formed correspondingly while the mass concentration of NaH2PO2· H2 O was 20 g / L and 35 g / L, respectively. The dissimilar Nb2 O5 particles were dispersed inside the crystalline and amorphous Ni-W-P / Nb2 O5 composite coatings which showed closely nodules structure. The XRD patterns of the coatings indicated that there was no diffraction peak related to the NdFeB substrate. When the Nb2 O5 mass concentration was increased from 5 to 15 g / L, the corrosion rate of the crystalline and amorphous coatings formed decreased markedly, whereas the corrosion rate of the coatings decreased tardily when the Nb2 O5 mass concentration was increased from 15 to 20 g / L. Conclusion The consolidated Nb2 O5 particles enhanced Ni-W-P / Nb2 O5 composite coatings could be prepared by electroless plating. And its corrosion resistance was improved with increasing Nb2 O5 concentration.