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为提高A356铝合金的表面防护性能,在A356铝合金基体上制备了Ni-P-B_4C复合镀层。采用SEM和XRD分别对镀层进行形貌观察和物相表征,利用显微硬度计和电化学工作站对镀层硬度和耐蚀性进行研究。结果表明:Ni-P镀层和Ni-P-B_4C复合镀层都较致密和平整,B_4C颗粒均匀弥散分布于复合镀层上;物相分析表明,B_4C的加入没有改变原二元镀层的非晶结构;B_4C加入使得复合镀层硬度显著提高,Ni-P-B_4C镀层硬度约为基体的8倍,Ni-P镀层的2倍;在3.5%Na Cl溶液中的塔菲尔极化曲线结果表明,Ni-P镀层和Ni-P-B_4C复合镀层都表现出良好的保护基体作用,二元镀层耐蚀性略优于复合镀层。
To improve the surface protection of A356 aluminum alloy, Ni-P-B_4C composite coating was prepared on A356 aluminum alloy substrate. The morphology and phase characterization of the coating were investigated by SEM and XRD respectively. The hardness and corrosion resistance of the coating were studied by microhardness tester and electrochemical workstation. The results show that the Ni-P coating and the Ni-P-B_4C composite coating are dense and smooth, and the B_4C particles are uniformly dispersed on the composite coating. The phase analysis shows that the addition of B_4C does not change the amorphous structure of the original binary coating; The hardness of the Ni-P-B_4C coating is about 8 times that of the matrix and twice that of the Ni-P coating with the addition of B_4C. The Tafel polarization curve in 3.5% NaCl solution shows that the Ni- P and Ni-P-B_4C composite coatings both showed a good protective matrix, and the corrosion resistance of binary coatings was slightly better than that of composite coatings.