Co/Ni比对93W-Co-Ni钨合金烧结温度及力学性能的影响

以Co、Ni作黏结剂,选择不同Co/Ni比,用粉末冶金法制备出HRC硬度在30⁴3之间的93W-Co-Ni钨合金。采用光学金相、扫描电镜对合金组织形貌进行表征,采用准静态拉伸试验对合金的抗拉强度及延伸率进行测试,采用洛氏硬度计对合金硬度进行测定。结果表明:随着Co/Ni比增加,合金的烧结温度逐渐增加,其抗拉强度与延伸率急剧降低,而硬度先增加之后趋于稳定;当Co/Ni≥1.0时,合金抗拉强度很低,延伸率≤1%;当Co/Ni≥4时,其HRC硬度值稳定在4143之间的93W-Co-Ni钨合金。采用光学金相、扫描电镜对合金组织形貌进行表征,采用准静态拉伸试验对合金的抗拉强度及延伸率进行测试,采用洛氏硬度计对合金硬度进行测定。结果表明:随着Co/Ni比增加,合金的烧结温度逐渐增加,其抗拉强度与延伸率急剧降低,而硬度先增加之后趋于稳定;当Co/Ni≥1.0时,合金抗拉强度很低,延伸率≤1%;当Co/Ni≥4时,其HRC硬度值稳定在41⁴3之间,明显高于一般的W-Ni-Fe合金,这主要与Co对W基体的润湿性较差及两者之间易形成脆性化合物Co7W6有关。     

Ag包覆ACR微球的制备及性能

采用盐基胶体钯和硝酸银活化工艺,以甲醛为还原剂,在丙烯酸酯类共聚物(ACR)微球表面化学镀银。利用电化学工作站研究pH值对镀液稳定性的影响,并通过扫描电镜(SEM),X射线能量色散谱仪(EDS)和X射线衍射仪(XRD)对复合粉体进行表面形貌、成分以及分布进行研究与分析。结果表明:pH值为12.9的镀液表现出较强的极化作用和稳定性,盐基胶体钯对ACR微球的活化效果优于硝酸银的相应活化效果,镀液中AgNO3浓度升高有助于Ag的析出,选用AgNO3浓度为15 g/L的镀液,可以制得镀层包覆完整、均匀、致密的银包覆ACR微球复合粉体。     

高介电常数栅介质的性能及与硅衬底间的界面稳定性

二氧化硅由于具有良好的绝缘性能及稳定的硅／二氧化硅界面而长期用于硅集成电路的制备。然而对于纳米线宽的集成电路，需要寻找新的高介电常数（高k）的栅极介质材料代替二氧化硅，以保持一定的物理厚度和优良的耐压及漏电性能。这些栅极候选材料必须有较高的介电常数，合适的禁带宽度，高质量的表面形貌和热稳定性并与硅衬底间有良好界面。此外，其制备加工技术最好能与现行的硅集成电路工艺相兼容。本文从固体物理和材料科学理论出发，阐述选择高k栅介质材料的基本原则，介绍目前研究的材料体系、制备方法、材料性能以及界面稳定性，并展望了这些高k栅介质材料的应用前景。     

电沉积Ni-S合金硫含量的影响因素

用电沉积法制备了Ni S合金电极, 研究了电流密度、镀液温度、镀液pH值、电沉积时间、硫脲浓度对镀层硫含量的影响; 测试了不同硫含量的极化曲线; 并用XRD、SEM对镀层进行了表征。结果表明硫含量随着电流密度、pH值的增高而降低, 随着镀液温度的升高、电沉积时间增长而增高; 在硫脲浓度为100 g/L时硫含量最高。硫含量在12.5%~16.5%时, Ni S合金电极析氢电位较低。所获得的镀层有Ni3S2 活性成分, 并有部分非晶态。镀层经电解后, 变得更细, 更均匀。     

铸造镍钼合金在浓盐酸介质中的钝化膜研究

本文采用多功能电子能谱仪，通过俄歇电子能谱AES和X光电子能谱，对在浓盐酸介质中的铸造镍铬合金的钝化膜进行了分析与研究。结果表明，该合金在50℃、36％HCl介质中，形成了一种含有Cl、Mo为主的氧化物膜。这层薄膜主要是Mo以MoO3形式在表面层富集，Ni在膜中主要以Ni2O3富集在膜的底部，因而提高了膜的稳定性。本试验中采用电化学方法形成的钝化膜厚度大约为10nm，过渡层厚度大约为15nm.     

粒度对锂离子电池用中间相炭微球电化学性能的影响

采用电化学测试手段,对锂离子电池用负极材料中间相炭微球的粒径分布对其电化学性能的影响进行了深入研究.结果表明,中间相炭微球的粒径对其大电流性能和循环寿命有着很大的影响,粒径越小,大电流性能越好,在2C倍率下,粒径40 μm的炭微球放电容量只有84mAh/g,粒径11μm的炭微球的放电容量仍然保持在223 mAh/g;50次循环后,粒径19 μm的炭微球循环性能最好,保持首次放电容量的92.7%,而粒径40 μm的炭微球只有首次放电容量的70%.     

TiO2/PS硬壳复合微球的制备及其电流变性能的研究

利用分散聚合法制备单分散的PS及交联PS微球,干燥后经CTAB重新分散制得PS微球分散液;无定型TiO2溶解于H2O2制得钛前驱体过氧钛酸(PTC),并将PTC缓慢滴加入PS微球分散液中,强烈搅拌加热制备得到了TiO2/PS复合微球。经扫描电镜观测,发现微球由于在过氧介质中反应表面发生了破裂;采用化学稳定性更好的交联PS微球,制得表面形貌完整的复合微球。经X射线衍射测定,证明复合微球中TiO2为锐钛矿型。因金红石TiO2介电常数强于锐钛矿型,其电流变性能较强。为了制备金红石TiO2/PS复合微球,向体系加酸以调节体系酸度,发现当加入0.5 ml浓硫酸时,制备得到了表面形貌完整,且表面TiO2晶型为金红石的复合微球,并且再加入少量PVP后,微球表面TiO2的量明显增多,经热重分析测定其含量为8%。将复合微球分散在氨基硅油中,测试其在不同电压下粘度与剪切应力随剪切速率的变化。结果表明使用复合微球作为电流变液固体相时沉降稳定性比纯提TiO2高了25倍;当分散体系两端电压为3000 V时,其屈服压力为525 Pa,最大粘度278.9 Pa.s。     

镀Ni金刚石与铜基结合剂间把持力的提高方法和机理分析

为了提高金刚石与金属结合剂间的把持力, 将镀Ni金刚石在1050℃下处理1 h, 然后用浓硝酸清洗金刚石表面, 最后采用真空热压烧结制备铜基结合剂金刚石样条。用扫描电子显微镜观察高温处理前后金刚石镀层表面形貌, 通过铜基结合剂样条的抗弯强度来评价金刚石与铜基结合剂间的结合力。用X射线衍射仪分析高温处理后镀层与金刚石间的物相。结果表明: 镀Ni金刚石经1050℃处理1 h后, 镀层基本上保持完整, 金刚石表面变粗糙; 铜基结合剂金刚石样条的抗弯强度从未镀金刚石的759 MPa增加到镀Ni金刚石的791 MPa, 再增加到高温处理镀Ni金刚石的833 MPa, 说明金刚石与铜基结合剂间把持力得到有效提高。     

添加剂对助镀液性能及批量法热镀锌镀层形成的影响

功能型添加剂的开发具有实际意义和应用价值,其可显著提高助镀盐膜的均匀性及干燥速率,减少镀件工序间锈蚀,从而降低铁离子带入锌锅而产生的锌渣量,得到的镀层细密均匀、性能优异。本文采用接触角测量仪、电化学性能测试和扫描电镜等手段来研究作者开发的功能型添加剂FB-108对助镀液及镀层性能的影响.结果表明:往传统助镀液中加入质量分数为0.3%FB-108,可显著降低助镀液的表面张力、改善其对镀件的浸润性,并提高了助镀液对镀件的缓蚀性;同时使制备的镀层形貌均匀、耐蚀性增加.     

电沉积制备铜钴颗粒膜

采用电沉积方法制备了铜钴巨磁电阻功能膜，研究了电沉积工艺参数，包括镀液的主盐离子浓度、配合剂浓度、pH值以及沉积时的电流密度等对铜钴颗粒膜层的组成的影响．用扫描电镜、金相显微镜、EDX能谱仪和XRD分析了镀层组成、表面形貌和结构．膜层的组成成分、晶粒大小与镀液的主盐离子浓度、配合剂浓度、pH值以及沉积时的电流密度有着直接的联系．镀液中钴离子浓度增大时，镀层中的钴含量相应的提高，镀层结晶更加粗大．镀层中铜离子浓度增大时，镀层中的铜含量提高，镀层结晶变得致密．配合剂柠檬酸钠浓度增加对镀层中钴的含量起到一定的抑止作用，而对铜的沉积则有促进作用，同时颗粒膜层结晶更加致密．低pH值下有利于铜的沉积，但此时镀层的晶粒较为粗大．控制电流密度可以改变镀层的组成，较高的电流密度有利于钴的沉积．     

The Effect of Nickel Electroplating on Corrosion Behavior of Metal Matrix Composites

Nickel electroplating was applied to A356.2 aluminum alloy and its composites for improving its corrosion resistance. The corrosion resistance of the A356.2 and composites reinforced with rice husk ash particulates was evaluated by potentio-dynamic polarization tests in aerated 3.5% NaCl solution. Composites were fabricated by using the liquid state processing technique. Scanning electron microscopy, energy dispersive spectroscopy, techniques were used for surface analysis of the coatings before the corrosion tests and optical microscope was used to study the surface morphology of the uncoated and coated specimens after polarization tests. Results demonstrated that the nickel coated specimens exhibited higher corrosion resistance than the uncoated specimens. However, it was noticed that there was no significant change in the corrosion resistance for the nickel plated composites.     

基体Cu粉粒度对制备镍包铜粉包覆效果的影响

在预先制备出不同粒度的Cu粉上采用化学沉积法制备超细镍包覆铜复合粉体,用扫描电子显微镜、能谱仪研究镍包覆铜粉末的微观形貌及成分,考察基体Cu粉的粒度对镍包覆效果的影响.结果表明:基体Cu粉的粒度越细镍包覆效果越好,但同时会降低粉体的分散性.     

Distribution of metallic phase in carbonado diamond polycrystalline composites

The structure of carbonado synthetic diamonds is studied by scanning electron microscopy. It is stated that the surface of the carbonado is coated by coarse diamond crystallites reaching 200 μm and having an open growth texture. Metal-catalyst (nickel) drops with submicrometer sizes were observed on the surface of the crystals. It is revealed that the synthetic carbonado structure is made of interpenetrating carcasses of diamond and metalloceramic phases.     

制备细镍包石墨粉末的动力学

控制反应速度是采用水热方法制备包覆粉末的关键技术之一。以细镍包石墨粉末为研究对象 ,探讨了制备过程中的一系列反应参数 :温度、表面活性剂、硫酸铵浓度、氨水浓度、氢分压以及初始溶液镍浓度等因素对反应诱导期、还原速度的影响 ,证明了这些参数控制着反应速度。     

Tribological Properties of Electroless Nanocomposite Deposits with Influence of Aliquat 336 on 6061 Aluminium Alloy

The process of electroless nanocomposite deposit on 6061 aluminium alloy was significantly enhanced with influence of Aliquat 336. The present investigation dealt with the analysis for the influence of Aliquat 336 surfactant on tribological properties of ENi–P–ZnO nanocomposite deposit on 6061 aluminium alloy sample. Wear resistance was calculated by pin-on-disc tribometer wear testing machine for the coated substrate by varying the surfactant concentration. Addition of surfactant has shown significant enhancement in the wear resistance of the coated surface. Surfactant was distinctively added in the chemical bath which resulted in decline of the surface tension, helped to bind the particles of nickel to the bubbles of hydrogen gas produced throughout the process of deposition. However, the impact of surfactant reached to its maximum value (critical micelle concentration) and got stabilized. The surface morphology and phosphorus content were characterized by field emission of scanning electron microscopy and energy dispersive X-ray analysis respectively. The worn surface morphology also revealed the abrasive wear mechanism. The complete experimental details, results obtained and their analyses have been presented in this paper.     

Laser surface alloying of nickel by molybdenum and aluminium— microstructural studies

It is now well established that a considerable improvement in the mechanical and chemical properties of the near surface regions of materials may be achieved by the use of high energy laser beams. By manipulating the laser power density and the time of interaction of the laser beam with an appropriately coated work piece, it is possible to achieve a surface chemistry that would have an improved resistance to wear, fatigue and corrosion failures. The change in chemistry at the surface is attained through the process of melting and mixing of the coating and a thin layer of the substrate. Solidification of this molten region at the surface results, due to an interplay of various forces, in the development of very complex microstructures. To analyse these in a piece of nickel that had been coated with a mixture of molybdenum and aluminium powders and then treated with a continuous wave CO₂ laser, extensive transmission electron microscopy was done on a thin foil obtained from near the bottom region of the recast pool. The foil was found to have a cellular microstructure comprising cells of the Ni₃Al (γ′) ordered phase. In the intercellular regions, two dispersed phases, namely, martensitic Ll₀ phase and Ni₂Al₃, and a contiguous phase, identified as a close derivative of the equilibrium δ-NiMo phase were found. A gradient in the degree of order could be observed within the γ′ cells. In the central portion of the cells, rapid solidification resulted, by the process of sequential ordering, in the development of a partially ordered alloy with very fine domains. In the peripheral regions of the cells, the alloy solidified by direct ordering into larger domains. This paper discusses some of these results.     

Magnetron Sputtered TiN Coatings Modified by Chromium,Nickel and Electroless Nickel (EN) Interlayers on Mild Steel

Abstract

TiN films were deposited by reactive d.c. magnetron sputtering on mild steel substrate. Because of presence of inherent porosity and internal stresses, TiN coatings cannot be relied to give corrosion protection; also TiN coatings need a good load support. Electroplated chromium and nickel and electroless nickel (EN) were deposited by plating as interlayers below the TiN coatings to study comparatively the effect of these interlayers. Chromium was electrodeposited from conventional sulfate catalysed chromic acid bath and nickel using Watt's bath while EN by electroless deposition process using acidic hypophosphite bath. Three different thicknesses viz. 2. 4 and 10 μm of interlayers were employed to study their influence on TiN coatings. The corrosion behaviour of TiN coated mild steel samples with and without the interlayers was studied using potemiodynamic measurement technique in deaerated IN H₂SO₄ electrolyte. It was observed that TiN coatings on mild steel without any interlayer almost mimic the behaviour of the substrate, while the presence of any of the three interlayers showed a considerable improvement in the corrosion resistance.

Microhardness measurements have shown that the surface hardness values of TiN coatings on mild steel increased to 1907 HK₂₅ from about 1000 HK₂₅ when employed with chromium interlayer. and to 1484 HK₂₅ with EN interlayer, while electroplated nickel as an interlayer increased the hardness to a lesser extent (1289 HK₂₅).

X-ray diffraction analysis has shown that the phases present in the TiN coatings were mainly TiN (200) and TiN (111). Chromium coated samples were found to show the broadening of Fe (110) peak, which also corresponds to Cr (110) peak. Interlayer nickel showed the presence of mainly Ni (200) and Ni (111) phases while EN was amorphous in structure. The crystalline phases Ni₃P and Ni were evident when TiN top-coat was given by d.c. magnetron sputtering on EN plated mild steel samples.     

Preparation and Properties of Iron Powder Plated with Nickel and Cobalt

The magnetic properties (magnetic induction and coercive force) of iron powder coated with nickel and cobalt as a result of chemical deposition from hypophosphite electrolytes are studied. Thermogravimetry, differential thermal and x-ray phase analyses are used to study in detail the kinetics and mechanism of high-temperature oxidation in air (up to 1200°C) for the original and coated powders. The phase composition of oxide films on specimens annealed at all temperatures of the DTA-curve peaks is determined. The possibility of increasing the high-temperature oxidation resistance of iron powder coated with nickel or cobalt is demonstrated.     

影响六方BN颗粒表面化学镀镍过程的因素及其ANN优化

在分析氨络合体系六方BN表面化学镀镍的热力学基础上 ,分别研究了影响镀覆反应速率的主要因素及其变化规律。用人工神经网络(ANN)方法对小型试验和放大试验的工艺参数进行优化与预测 ,试验结果与预测结果基本吻合 ,表明对本研究体系的ANN方法优化与预测可用于指导实践 ,并克服了多因素复杂体系及交互影响带来研究的困难。     

镀TiN金刚石与结合剂之间的结合状态研究

利用抗弯强度试验、扫描电镜及能谱分析研究了镀ＴｉＮ金刚石在Ｆｅ基，Ｎｉ基，Ｃｕ基及Ｃｏ基结合剂中的界面结合状态。结果发现，金刚石表面镀ＴｉＮ后，其Ｆｅ基、Ｎｉ基和Ｃｕ基复合材料的抗弯强度均下降，而Ｃｏ基复合材料抗弯强度上升。