20R钢表面Ni-Cu-P和Ni-P化学镀层性能研究

Study on Properties of Ni- Cu- P Coating and Ni- P Coatings on 20R Steel Substrate

为了改善20R钢在NaOH溶液中的耐蚀性,在材料表面制备了Ni-P和Ni-Cu-P合金镀层。测试了20R钢、Ni-P与Ni-Cu-P镀层在质量分数为15%的NaOH溶液中的极化曲线和交流阻抗。结果表明:Ni-P及Ni-Cu-P镀层的维氏硬度分别是20R钢的2.29和2.49倍;在质量分数为15%NaOH溶液中,20R钢、Ni-P和Ni-Cu-P镀层的极化电位分别为-998,-611和-494 mV,20R钢的自腐蚀电流密度分别是Ni-Cu-P及Ni-P镀层的27.35和5.62倍。20R钢测试电阻分别是NiCu-P和Ni-P镀层的0.51和0.64倍。Ni-P与Ni-Cu-P镀层能在20R钢表面发生沉积并镀层光滑、致密、缺陷少,阻隔了质量分数为15%NaOH溶液与20R钢的直接接触,从而改善了20R钢的耐蚀性能。Ni-Cu-P镀层的耐蚀性更优于Ni-P镀层。

To improve corrosion resistance of 20R steel in NaOH solution, Ni-P and Ni-Cu-P alloy coatings were prepared on the surface of steel material. The coating hardness is tested by Vivtorinox hardness tester. Morphology and structure of the coating were analyzed by scanning electron microscope and X-ray diffraction （XRD）. The polarization curve and corrosion resistance of 20R steel, Ni-Cu-P and Ni-P alloy coatings in 15wt% NaOH solution were tested by electrochemical system. The results show that： the HV hardness of Ni-P coating and Ni-Cu-P coating were 2.29 and 2.49 times that of 20R steel respectively; In the solution with mass fraction of 15% NaOH, polarization potential of 20R steel, Ni-P and Ni-Cu-P coatings were -998 mV, -611 mV and -494 mV respectively. The corrosion current density of 20R steel was 27.35 times that of Ni-Cu-P coatings and 5.62 times that of Ni-P coating. Testing resistance of 20R steel was 0.51 times that of Ni-Cu-P coating and 0.64 times that of Ni-P coating. Ni-P and Ni-Cu-P coatings can be smoothly deposited in 20R steel surface. The coating is smooth, dense and few in defects. It hindered the direct contact of 20R steel with 15 wt % NaOH solution, and improved the corrosion resistance of 20R steel. The corrosion resistance of Ni-Cu-P coating is superior over that of Ni-P coating