【作者】 张霞；

【导师】 何荣恒；

【作者基本信息】 东北大学 ， 物理化学， 2009， 硕士

【摘要】 块体纳米晶工业纯铁(BNⅡ)是将普通工业纯铁(CPⅡ)通过深度轧制技术制得的块状纳米材料。化学镀镍磷是一项表面处理技术,是化学镀技术最具代表性且应用最广泛的一种。化学镀镍磷是利用次磷酸钠为还原剂,使镀液中的镍离子直接在具有催化活性的基体表面还原,同时磷共沉积而形成镍磷镀层的一种镀镍工艺。本文采用高温(88℃)酸性(pH 4.4-4.5)化学镀Ni-P合金的方法制得了高磷(12-14 wt%)非晶镀层,并利用其高硬度、耐磨性、抗腐蚀性对BNⅡ进行修饰和保护。研究内容包括最佳施镀工艺的研究,采用扫描电镜形貌分析仪、能谱分析仪、X射线衍射分析仪、X射线光电子能谱、金相显微镜、硬度计、电化学工作站等仪器对镍磷镀层的结构形貌、孔隙率、硬度、结合力、腐蚀性能等相关性能的研究。同时对BNⅡ与CPⅡ化学镀镍磷的性能及沉积机理进行对比研究,以期使用BNⅡ较适用CPⅡ在化学镀镍磷性能方面有所改善。制备了光泽度及平整度优良的高磷(P wt%11-13%)镀层,厚度为24±1μm,具有零孔隙率,结合力良好,化学镀镀态的硬度为HV 506,经390℃热处理1h后可达HV 936。镀膜为非晶结构,加热可使其晶化,生成Ni和Ni3P两相,BNⅡ镀层晶化温度为340℃,镀层在883℃时熔化。由Tafel极化实验知,在5% NaCl和0.5 mol/LHC1溶液中,BNⅡ镀层与BNⅡ相比,自腐蚀电位Ecorr分别正移216 mV和197 mV；CPⅡ镀层Ecorr与CPⅡEcorr相比,分别正移50 mV和118 mV；BNⅡ镀层自腐蚀电流密度icorr(8.956×10-6A/cm2,4.215×10-5A/cm2),较BNⅡ的icorr(1.303×10-5A/cm2,1.326×10-4A/cm2)明显减小。X射线光电子能谱分析表明,在化学镀最初期,BNⅡ与CPⅡ相比,其化学镀Ni-P镀层中P 2p3结合能高出0.9 eV；Ni 2p3结合能降低0.1 eV,Ni 2p1结合能降低0.3 eV；Fe 2p3结合能降低0.2 eV,Fe 2p1结合能降低0.4 eV。更多还原

【Abstract】 Bulk nanocrystalline ingot iron (BNII) was produced from conventional polycrystalline ingot iron (CPII) by the severe rolling technique.Electroless nickel-phosphorus (Ni-P) is a technique for solid surface treatment. It has been adopted as representative chemical plating and widely applied in industry. Electroless Ni-P using sodium hypophosphite as a reducing agent, therefore the nickel ion is reduced directly on the catalytic reducting surface of the substrate from Ni-plating solution, and phosphorus is co-deposited simultaneously. Thus chemical Ni-P plating is performed.In this paper, high phosphorus (Pwt% 11%-13%) amorphous plating was obtained by optimum Ni-P electrless plating process at high temperatures of 88℃The acidity of the plating solution was controlled as 4.4-4.5 in pH with a buffer solution. Characterization of nickel-phosphorus plating including the structure and morphology, porosity, hardness, bonding strength, and corrosion resistance properties was made by using scanning electron micrograph, X-ray diffraction analyzer, X-ray photoelectron spectroscopy, metallographic microscope, hardness tester, chi660c electrochemical workstation equipment, respectively. The deposition mechanism of electroless Ni-P on BNII and CPII was studied, and improvement of electroless Ni-P plating on BNII was expected.The experimental results indicated that the prepared Ni-P plating has excellent gloss smoothness, zero porosity, and nice binding force. The thickness of the Ni-P plating was 24±1μm. The hardness was increased from HV 506 at the very beginning of chemical plating to HV 936 after treating at 390℃for 1h. The structure of Ni-P plating is amorphous at room temperature. A crystallized structure with two-phase Ni and Ni3P could be formed at elevated temperatures. The crystallization temperature of the plating on BNII was 340℃, and the melting point was about 883℃. According to the Tafel polarization analysis,in 5% NaCl and in 0.5 mol/L HCl solutions, the corrosion potential Ecorr of BNII with the plating is 216 mV and 197 mV higher than that without plating, respectively; The corrosion potential Ecorr of CPII with the plating is 50 mV and 118 mV higher than that without plating, respectively; Meanwhile, corrosion current density icorr of BNII with the plating (1.303×10-5 A/cm2,4.215×10-5 A/cm2, respectively) are obviously lower than those of BNII without plating (1.303×10-5 A/cm2,1.326×10-4 A/cm2, respectively).According to the X-ray photoelectron spectroscopy, the binding energy of the earlier plating was increased in 0.9 eV for P 2p3; decreaded in 0.1 eV for Ni 2p3 and 0.3 eV for Ni 2p1; decreased in 0.2 eV for Fe 2p3 and 0.4 eV for Fe 2p1, respectively, by comparing the results obtained from BNII plating with those from CPII plating.更多还原