退除不良镀层的方法(二)

介绍了锌合金件上不良铜镀层的退除法,不良金镀层、锡镀层、铅锡合金镀层,以及钢铁上其他不良镀层的退除法.     

脉冲电镀中脉冲参数对镍镀层显微硬度的影响

采用传统的瓦特镀液通过脉冲电镀制得纯镍镀层。研究了脉冲参数对镀层微观形貌与显微硬度的影 响。结果表明:镀层表面形貌为胞状结构;随着脉冲峰值电流密度的增加,胞状结构的尺寸逐渐变小,镀层显微硬度先增 加后减小;随着占空比的减小,最大显微硬度值对应的峰值电流密度增大,占空比减小到一定值后,峰值电流密度的改变 对显微硬度影响不再明显。     

离子束加速电压对真空电弧沉积Ti(C,N)涂层性能的影响

利用等离子辅助真空电孤沉积技术分别在高速钢片和单晶硅片制备了Ti(C,N）涂层，通过X-射线衍射和扫描电镜研究了不同离子加速电压对单晶硅片上涂层结构和组织形貌的影响，并测定了高速钢片上涂层的显微硬度，同时进行了耐磨性实验。结果表明：涂层主要由TiN和Ti(C,N）组成，随着离子束加速电压的增大，涂层的沉积速度增大，Ti(C,N）的衍射峰不断宽化，晶格尺寸发生变化，但其表面形貌不受影响；当离子束加速电压为1500V时，涂层有较高的耐磨性和显微硬度，当离子束加速电压为2500V时，涂层的耐磨性和显微硬度都有所下降：     

超声波化学镀Ni-Cu-P合金

在有机高分子聚合物薄膜,如投影仪专用胶片上超声波化学镀M—Cu—P合金,研究了镀液各组分浓度、pH值变化对沉积速度的影响：通过扫描电镜(SEM)观测镀层的表面形态及厚度,并用其所附带的能谱(EDS)分析镀层成分,采用透射电镜(TEM)观测镀层中粒子的微观形貌及大小,利用X-射线衍射(XRD)表征镀层的微观结构。结果表明,M—Cu—P合金化学镀层为非晶态合金,光亮、均匀,与基体结合面平整：镀层厚度100μm,镀层颗粒大小在30～40nm,各成分含量分别为77．73％～90．64％Ni,0．38％～5．27％Cu,7．23％～14．30％P。     

复合电沉积工艺研究现状

对电沉积制备金属基复合镀层过程中各种工艺参数包括微粒粒径、微粒含量、搅拌强度、镀液pH值、电流密度、温度和表面活性剂类型等因素对镀层中复合微粒含量的影响的研究现状进行了综述。讨论了复合电沉积过程的可能的机理,指出了今后的发展方向。     

Ni-C复合镀层在高分子PTC热敏电阻器上的应用

给出了Ni-C复合镀层生产工艺流程及工艺规范。介绍了提高铜箔粗化度及加强碳黑分散的工艺措施。讨论了电流密度、pH、温度及搅拌等操作对镀层及Ni-C共沉积的影响。总结了镀液维护及注意事项。实验结果表明,该Ni—C复合镀层制作的电极片质量全部达到PTC热敏电阻器性能要求。     

Reforming of methane with carbon dioxide over supported bimetallic catalysts containing Ni and noble metal: I. Characterization and activity of SiO2 supported Ni–Rh catalysts

Cobalt catalysts supported on silica aerogel have been prepared using sol–gel chemistry followed by drying under supercritical ethanol conditions. Three different loadings of cobalt were synthesized: 2, 6, and 10% by weight. Transmission electron micrographs indicate that the metallic cobalt exists as discrete particles 50–70 nm in diameter for the 2 and 6% loadings. The 10% catalyst shows long needles of cobalt. BET and BJH measurements indicate that the catalysts retain the silica aerogel properties of high surface area (∼800 m²/g), large pore volume (∼5 cm³/g), and an average pore diameter in the mesoporous regime (∼25 nm). The catalysts were evaluated for Fischer–Tropsch activity in a laboratory-scale packed bed reactor. All three catalysts were active with the 10% Co catalyst achieving more than 20% CO conversion which corresponds to a rate of 1.53 g CO per g-cat per hour. The catalysts were selective for the C₁₀₊ hydrocarbons with more than 50% of the carbon contained within this fraction. A significant portion of the C₉–C₁₅ hydrocarbon product was observed as 1-olefins which reflects the enhanced mass transport within the very porous aerogel support.     

Electrodeposition of nickel in the presence of Al<Superscript>3+</Superscript> from sulfate baths

The effect of Al³⁺ on the cathodic current efficiency, deposit morphology, crystallographic orientations and polarisation behaviour of the cathode during electrodeposition of nickel from acidic sulfate solutions was investigated. Higher concentration of Al³⁺ (>10 mg dm^–3) significantly deteriorated the surface quality of the nickel deposit as well as the current efficiency. X-ray diffraction studies revealed that the (200) plane was the most preferred crystal plane and was not affected by the presence of varying concentration of Al³⁺ in the electrolytic bath. The presence of Al³⁺ caused polarisation of the cathode, which increased with increasing Al³⁺ concentration. The effect of Al³⁺ on the electrokinetic parameters: Tafel slope (b), transfer coefficient () and exchange current density (i₀) were also investigated.     

用于微机械器件的Fe-Ni合金电镀沉积膜的性能

结合Si体微机械技术和电镀技术加工出Fe-Ni/Cu/Si复合悬臂梁,其中Fe-Ni膜厚3 μm,Cu膜厚0.2 μm.利用共振法首次测出在1.3 Pa气压下,复合悬臂梁中Fe-Ni(Fe 64,Ni 36,质量分数,%,下同)电镀沉积膜的内耗为10-3.利用自行设计的微力/微位移天平法,测出Fe-Ni(Fe 57,Ni 43)/Cu/Si复合悬臂梁的Young's模量为1.0×1011N/m2.Fe-Ni电镀沉积膜的内应力随膜中Fe含量的增加先是增大然后减小.在Invar合金(Fe 64,Ni 36)成分附近达到最大约300 MPa.Fe-Ni电镀膜的热膨胀系数与膜中Fe含量关系则与内应力相反,但与合金体材料变化趋势一致,在Invar合金成分附近达到最小,其值高于相应成分的合金体材料,约6×10-6/℃.     

我国铝土矿资源综合分析

综合分析了我国铝土矿资源分布格局、矿床特征和矿石特点及其对氧化铝工业的决定性制约作用,为我国铝工业"十·五"及其远景规划提供资源基础资料与建议.