镁合金表面铈多层膜的抗腐蚀性及细胞相容性研究

利用旋转涂布法在镁合金表面构建了由聚乙烯亚胺(Polyethyleneimine,PEI)、明胶(Gelatin,Gel)和硝酸铈(Cerium nitrate)组成的抗腐蚀性铈多层膜.采用接触角测试仪表征了铈多层膜在镁合金表面的组装过程;利用电化学交流阻抗图谱和极化曲线研究了铈多层膜修饰的镁合金在0.14mol/L NaCl溶液中的抗腐蚀性能;以MTT和碱性磷酸酶考察了铈多层膜修饰镁合金的细胞相容性.结果表明,在镁合金表面形成了铈多层膜结构,铈多层膜表面处理提高了镁合金的抗腐蚀性能和细胞相容性.该表面处理为镁合金植入体的应用提供了新思路.     

镁合金磷化处理对化学镀镍层性能的影响

为了有利于环保,采用磷化工艺对AZ31B镁合金进行化学镀镍前处理.采用直观法、扫描电子显微镜和阴极极化曲线法对磷化膜及其化学镀镍层进行了分析.结果表明:AZ31B镁合金表面经磷化处理后得到了良好的化学镀镍层;AZ31B镁合金化学镀镍层的耐蚀性随磷化时间的延长先增加后减小,当磷化时间为75 s时,化学镀镍层的腐蚀电势比直...     

镁合金表面电镀前处理新工艺

常用的镁合金电镀前预处理时需预镀锌、预镀铜,还需使用氰化物,不仅污染环境,且预处理工艺复杂.为此,研究了AZ91D镁合金焦磷酸盐体系电镀铜的前处理工艺.分析了酸洗、活化、浸锌液主盐、配位剂、浸锌温度、浸锌时间等工艺参数对浸锌层质量的影响,确定了前处理工艺的优化条件.采用增重法测试了浸锌层的膜重,用电化学方法研究了镁合金的浸锌过程及浸锌层的耐蚀性能,用划痕、热震和锉刀法测试了经该前处理后所得镀铜层与基体的结合力.结果表明:采用该工艺电镀铜所得镀层细致、光亮,镀层与基体结合力良好,对镁合金基体有较好的防护作用.     

镁合金铬磷化工艺的试验研究

利用正交试验法和对比实验法研究了一种镁合金铬磷化处理工艺,通过分析计算获得了AZ91D镁合金铬磷化处理液的最佳配方及工艺参数:铬酐12 g/L,次磷酸钠20～30 g/L,室温处理8min.用该工艺方法处理AZ91D镁合金,表面得到了一层致密均匀、附着力和耐蚀性良好、厚度为2.5～3.5 μm的铬磷化膜层,将其用于涂装前的打底层可以大大提高漆膜的附着力和耐蚀性能.该工艺对镁合金的涂装生产具有一定的参考价值.     

AZ91D镁合金前处理工艺对化学镀镍的影响

为了获得适合在AZ91D镁合金上进行化学镀镍的前处理工艺,借助扫描电子显微镜、金相显微镜等设备研究分析了不同前处理工艺对AZ91D镁合金化学镀镍层形貌及性能的影响,并确定了更适合在镁合金上进行化学镀镍的酸洗和活化工艺.结果表明,经此工艺处理后的镁合金表面均匀平整,施镀后可获得表观平整光亮、胞状结构均匀致密、与基体结合力及耐蚀性良好的非晶态Ni-P合金镀层.与常用的处理方法相比,这种新工艺处理温和,更适合在镁合金上使用.     

镁合金表面Ti—TiN复合镀层的阴极多弧离子制备与表征

表面强化、耐蚀处理对镁及其合金的应用至关重要。采用阴极多弧离子镀膜技术，在AZ91C镁合金基底上首次成功镀制了强结合力的以Ti为过渡层的TiN复合膜层，并利用高分辨扫描电子显微镜（SEM）、X射线能谱仪（EDS）、CSM显微划痕测试等技术对复合膜层的形貌、组织结构及性能进行分析研究。结果表明，采用适当的多弧离子镀膜工艺，能在经恰当预处理方法处理的镁舍金基底上制备性能良好的TiN膜。膜层均匀、致密，膜基结合力达130mN以上，复合硬度达500HV左右（AZ91镁合金基底125HV）。此外中性盐雾强化实验表明，经该方法处理后的镁合金在ASTM-B117标准测试条件下，腐蚀速度明显降低，经过200h后，表面无明显腐蚀现象。真空多弧离子镀膜技术有望在镁合金表面防护领域得到应用。     

摩托车轮毂镁合金微弧氧化工艺

微弧氧化技术试验研究多,但大型生产应用较少.为此,以大面积镁合金轮毂为例,探讨了镁合金微弧氧化的实际应用,并对镁合金轮毂微弧氧化的工艺参数进行了优化,对膜层的质量进行检测.结果证明:微孤氧化用于镁合金轮毂表面处理效果较好,对大面积镁合金表面处理有着重要的参考价值.     

镁合金化学镀镍层的性能研究

化学镀镍是镁合金保护的重要手段.为探讨化学镀镍对镁合金的保护效果,本文利用电化学极化曲线、X射线衍射和扫描电镜等手段研究了镁合金化学镀镍前处理方法及镀层性能.镁合金上化学镀镍层厚度达到15μm时已没有惯穿镀层的孔隙,200℃以上热处理可显著提高镀层结合力;由于镀层和镁合金间强烈的电偶腐蚀作用,在户外或潮湿环境中,化学镀镍对镁合金而言是一种有较大风险的防护方法.为获得更好的保护效果,多层化学镀或电镀与化学镀相结合是较好的选择.     

微弧氧化和阳极氧化处理镁合金的耐蚀性对比

通过电化学分析测量镁合金微弧氧化陶瓷层和阳极氧化陶瓷层的交流阻抗图谱，稳态电流／电位曲线，并对得出的交流阻抗值和腐蚀电流进行比较，结果表明，与阳极氧化处理比较，镁合金经营微弧氧化处理后交流阻抗值增大，腐蚀电流降低，微弧氧化陶瓷层特有的微观结构是其耐蚀性显著提高的主要原因。     

环保型镁合金化学镀镍工艺研究

研究了镁合金的环保型化学镀镍工艺,对前处理工艺进行了简化,对镀液的稳定性、循环使用后的节约成本核算以及废液的回收处理等进行了研究和探讨.结果表明,使用一步前处理工艺能简化镁合金前处理工艺,提高镀镍层的结合强度和质量,且处理液中不含Cr6 、HF等对环境和人体有害的物质;化学镀液的循环使用可以大幅度节约生产成本,减少废液排放,提高资源的利用率.     

Assembly of phase transferred nickel nanoparticles at air-water interface using Langmuir-Blodgett technique

Development of simple and efficient protocol for the synthesis of Ni nanoparticles in aqueous media and their subsequent phase transfer to organic media is reported. The synthesis of nickel nanoparticles in aqueous medium is accomplished by reducing the nickel nitrate with sodium borohydride in presence of oleic acid. It results in the formation of nickel nanoparticles capped with oleic acid. The pristine oleic acid capped nickel nanoparticles were then phase transferred to nonpolar solvents such as toluene using stearic acid. The phase transfer was effective probably due to the space exchange between the oleic acid moiety and stearic acid molecules. The hydrophobized Ni thus obtained was organized at the air-water interface and it was observed that by controlling the pressure and concentration of hydrophobized Ni nanoparticles at air-water interface, linear ribbon like assemblies could be obtained. The organization process was followed by surface pressure-area isotherm measurement and Brewster Angle Microscopy.     

Integrated bacterial process for the treatment of a spent nickel catalyst

Integrated biological processes involving the dissolution and subsequent precipitation have been used for the treatment of the spent material from the hydrogenation of vegetable oil containing a high-level of nickel. Our results show that nickel was successfully leached using Acidithiobacillus thiooxidans. The percentages of nickel leached using A. thiooxidans were higher than those obtained with dilute sulphuric acid solutions. Due to the physical characteristics of the residue, the best results were obtained when the leaching process was carried out using sulphuric acid biogenerated by an A. thiooxidans biofilm. The recovery of nickel from the leachates was performed at room temperature by precipitating with sulphide generated by Desulfovibrio cells. Indirect precipitation using sulphide generated in Desulfovibrio sp. cultures allowed the recovery of nickel as the very insoluble nickel sulphide.     

一种新型热成像材料

本文对以水溶性聚乙烯醇（PVA）为粘合剂，硬脂酸镍（NiSt2）为主要原料，焦性没食子酸（PGA）为显影剂的一种新型热成像材料的研究。通过紫外可见光谱研究了硬脂酸镍与焦性没食子酸在戊醇溶液中的相互作用，实验结果表明硬脂酸镍与焦性没食子酸按1：1形成配合物。     

Synthesis of nickel picrate energetic film in a 3D ordered silicon microchannel plate through an in situ chemical reaction

Micro-energetic devices with energetic and functional diversity have attracted interest from scientific communities, through features such as the integration of energetic materials into micro-electro-mechanical systems (MEMS). In this study, a method for the preparation of nickel picrate energetic films on the sidewalls of a silicon microchannel plate (Si-MCP) is presented. The Si-MCP was produced by a photoelectrochemical process and a thin film of nickel (Ni) was synthesized by electroless plating of Ni on the sidewalls of the Si-MCP. The thin film of nickel picrate was successfully produced via an in situ chemical reaction method by introducing picric acid into the 3D ordered nickel/silicon microchannel plate (Ni/Si-MCP). Field emission scanning electron microscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy were used to study the morphological and structural properties of the thin film. The results demonstrate that picric acid reacted with Ni to form a nickel picrate thin film. Also, differential scanning calorimetry and thermogravimetric analysis were employed to characterize the thermal decomposition of the energetic film. The approach can solve the problem of integrating organic energetic materials with MEMS devices. Also, nickel picrate can release a mass of energy and gas simultaneously, which further enhances the functional diversity of MEMS devices.     

原子吸收分光光度法测定土壤中的镍的方法研究

本文对微波消解-原子吸收分光光度法测定土壤样品中的镍元素的分析方法进行了探讨,并对不同类型土壤消解后赶酸与不赶酸的测定结果进行了比较。结果表明,原子吸收法测定土壤中的镍必须赶酸,但赶酸的方法可以简化,并利用连续光源原子吸收光谱图进行了验证。     

炔醇类添加剂在光亮镀镍液中的阳极电化学反应

采用紫外分光光度法研究了丁炔二醇和丙炔醇在光亮镀镍过程中的阳极氧化反应,以期进一步认识添加剂在电镀过程中的作用机理.结果表明,炔醇类化合物在阳极生成了相应的有共轭体系的炔醛类和炔酸类化合物,产生了紫外吸收.当镍阳极处于钝化状态时阳极上有氯气产生,炔醇类氧化物的生成速度较快.选择活性镍作为光亮镀镍阳极,可以减少炔醇类光亮剂的氧化.     

Korrosionsuntersuchungen an drei Stählen und einer Nickellegierung in Mono- und Trichloressigsäure

Investigations Into the Corrosion of Three Steels and one Nickel Alloy in Mono- and Trichloroacetic Acid The corrosion resistance of three steels and one nickel alloy was investigated in aqueous and nonaqueous monochloroacetic acid and in nonaqueous trichloroacetic acid at various temperatures. There is no difference in the corrosion behaviour of the steels whereas the resistance of the nickel alloy is better in all cases by a factor 10. In aqueous monochloroacetic acid the corrosion attack is due to the hydrolytic formation of hydrochloric acid. Nonaqueous monochloroacetic acid behaves more corrosive than nonaqueous trichloroacetic acid.     

Bright and hard electrodeposits of nickel from nickel acetate—formamide bath

Abstract

The electrodeposition of nickel from nickel acetate dissolved in pure formamide was carried out and the effect of pH, current density, temperature, and boric acid concentration was studied. The temperature range of 40–50°C was found to be the best operating parameter at which usually bright and hard deposits having high cathode current efficiencies were obtained. A concentration of 0·1M boric acid in conjunction with 0·2M ammonium acetate resulted in deposits having exceptionally high levels of hardness. Variation of pH by hydrochloric acid led to bright, fine grained hard deposits, while changing pH by acetic acid possessing bulkier acetate ions resulted in soft and thin electrodeposits. Scanning electron microscopy revealed refinement in grain size with increasing temperature. A definite change in microstructure occurred when nickel electroplates were annealed to 400–600°C for 1 h and cooled slowly under atmospheric pressure.

MST/746     

Preparation and characterization of NiO nanoparticles through calcination of malate gel

NiO nanoparticles have been successfully prepared by calcining malate gel, using basic nickel carbonate (BNC) and malic acid as the raw materials and H₂O as the solvent. The reaction was studied by TG–DTA, XRD and FT-IR. The particle size and morphology of NiO nanoparticles was characterized by TEM. The results show that nickel malate could be formed by the reaction of BNC and malic acid; the gel was composed of nickel malate and residual malic acid; the precursor can translate into NiO nanoparticles completely at 400 °C under the air, and the as-prepared sample has a cubic crystal structure with about 14 nm of average diameter by the Scherrer formula. The NiO calcined at 400 °C for 1 h was of narrow particle size distribution, weak agglomeration and small particle size. The particle size of NiO increased with the increase in temperature. Compared with other methods, the developed method is simple and the raw materials were inexpensive, so that it has the potential for further scale-up application in the industry. Furthermore, the reason for the metallic nickel formation in the course of the preparation was explained.     

Recovery of nickel and cobalt from organic acid complexes: adsorption mechanisms of metal-organic complexes onto aminophosphonate chelating resin

This study examined the recovery of nickel and cobalt from organic acid complexes using a chelating aminophosphonate Purolite S950 resin. These metal complexes are generated by bioleaching nickel laterite ores, a commercial nickel and cobalt mineral oxide, with heterotrophic organism and their metabolites or organic acid products. Equilibrium adsorption tests were conducted as a function of Ni and Co concentrations (15-2000 mg/L), solution pH (0.01 and 0.1 M acids) and three metabolic complexing agents (citrate, malate and lactate). It was shown that the adsorption of the various Ni- and Co-complexes on Purolite were quite low, 16-18 and 5.4-9 mg/g of resin, respectively, in comparison to the smaller nickel ions and nickel sulfate. This was attributed to the bulky organic ligands which promoted crowding effect or steric hindrance. The adsorption of these complexes was further hampered by the strong affinity of the resin to H+ ions under acidic conditions. Mechanisms of adsorption, as inferred from the fitted empirical Langmuir and Freundlich models, were correlated to the proposed steric hindrance and competitive adsorption effects. Nickel and cobalt elution from the resin were found be effective and were independent of the type of metal complexes and metal concentrations. This study demonstrated the relative challenges involved in recovering nickel and cobalt from bioleaching solutions.