空心玻璃微珠表面包覆Ni-P／Co-Fe-P复合镀层的研究

通过化学镀在空心玻璃微珠（HGM）表面沉积了镍磷合金颗粒镀层，利用偶联取代传统的粗化处理，结合适当的镀覆工艺实现了镀层与微珠的紧密结合并达到了均匀完整包覆；在此基础上，进行了镍磷镀层表面湿化学还原法包覆钴铁合金的研究。利用扫描电子显微镜、X射线能谱仪、X射线衍射仪及振动样品磁强计对包覆层的形貌、组成、晶体结构和改性后微珠的静磁性能进行了分析测试。结果表明，复合镀层由非晶态合金组成，其中镍磷镀层为单层颗粒膜，而后续沉积的钴铁合金镀层呈条带状生长于镍磷镀层表面；沉积钴铁合金后微珠的磁性有了明显改善。     

羰基镍粉——国内市场潜力较大

羰基镍的生产工艺并不是一项最新技术，已有近百年的研究历史，我国亦有几十年的研究时间。羰基法精炼镍是一种工艺简单，能耗低、提取率高，而且有利于贵金属富集的无三废环保工艺，可生产出高纯金属镍丸、金属粉末、合金粉末、包覆粉末、泡沫镍及纳米镍粉等产品，但长期以来，由于市场对高纯镍粉等产品需求不大，限制了羰基镍的发展。     

纳米镍包覆氮化硅粉体的制备和磁性能研究

利用一种简单的无催化化学镀法制备了纳米镍晶粒包覆氮化硅陶瓷的复合粉体.通过不同的反应PH值和搅拌工艺对比获得了较为均匀的包覆.利用X射线衍射、扫描电镜和透射电镜对包覆粉体的物相及显微形貌进行表征分析.磁性能测量表明包覆粉体具有良好的铁磁性能和磁各向异性.     

聚苯胺包覆镍纤维的制备及电性能研究

镍纤维经预处理后,采用化学氧化法对其进行包覆改性,制备聚苯胺包覆改性镍纤维,以改善镍纤维的电性能。主要探究了掺杂剂种类、浓度、镍纤维长径比以及搅拌速率等因素对聚苯胺包覆镍纤维效果的影响,利用核磁共振、能谱仪和扫描电镜对产物进行元素和形貌分析,采用四探针电阻率测试仪测试聚苯胺包覆镍纤维的电性能。结果表明:以0.1mol/L盐酸为掺杂剂,将长径比为8mm的镍纤维在0～5℃下以60r/min的转速聚合得到聚苯胺包覆镍纤维材料,其包覆层致密均匀,且得到最大的电导率,其值为2.62×103S/cm。     

颗粒包覆对Al_2O_3/青铜复合材料界面结合模式及性能的影响

采用化学镀的方法在Ａｌ２Ｏ３颗粒表面包覆镍或铜，研究了颗粒包覆对Ａｌ２Ｏ３／青铜复合材料界面结合模式及性能的影响。ＸＲＤ结果表明，包镍后，复合材料的界面有化学反应发生，生成Ｎｉ２Ａｌ３相，复合材料的界面结合强度因此而增加；包铜后，复合材料的界面无化学反应发生，但因机械锁合作用加强，也使复合材料的界面结合加强。颗粒包覆使复合材料的界面结合模式改善。研究表明，Ａｌ２Ｏ３颗粒表面包覆镍或铜对复合材料的致密度和力学性能（硬度、拉伸强度和耐磨性）有较大的影响     

界面聚合法制备管状聚苯胺/聚苯胺包覆镍纳米复合材料及其电磁特性

采用工艺简单的界面聚合法制备了管状聚苯胺(PANi)及管状聚苯胺/聚苯胺包覆镍纳米粒子(PANi/PANi(Ni))复合材料。上层油相采用正己烷,下层水相采用稀盐酸溶液,将两相混合并添加镍纳米颗粒,在两相的界面处发生化学复合反应。通过FT-IR、XRD、TEM分析表征表明,生成了管状聚苯胺,形状均一,直径大约在100nm,并且存在着部分的结晶。聚苯胺很好地包覆了纳米镍粉,实现了管状聚苯胺及聚苯胺包覆纳米镍粉的多种物质及形态的复合,对其制备工艺及微波频段的电磁特性进行了研究。     

球形钕铁硼磁粉表面电沉积镍后的性能研究

钕铁硼磁粉表面包覆金属镍层后,可以在300 ℃左右与聚合物复合制备性能优良的磁体.为了研究金属镍层在钕铁硼磁粉表面的包覆特性,采用电沉积方法在球形钕铁硼磁粉表面包覆一定厚度的镍层,采用扫描电镜(SEM)和热分析仪研究了包覆镍磁粉的表面形貌和抗氧化特性,用振动样品磁强计和液压式万能试验机研究了包覆镍后的球形粉和300 ℃高温处理后粘结磁体的磁性能和抗压强度.结果表明,球形磁粉经包覆镍处理后,磁粉的高温抗氧化性、粘结磁体的抗压强度明显提高.     

Ni包覆Al2O3粉体的RCVD法制备及机理研究

金属Ni包覆于陶瓷粉体的表面,可以促进其烧结、提高导电性或赋予新的功能性质.本文采用旋转化学气相沉积法(RCVD),利用二茂镍(NiCp_2)前驱体的热分解,借助载体氢气对反应的催化促进作用,在Al_2O_3粉体表面包覆了均匀分散的Ni纳米粒子,并研究了包覆温度和原料供应速率对反应产物物相、粒度和形貌的影响规律.研究表明,在包覆温度为450~550℃、前驱体二茂镍(NiCp_2)供给速率为(0.6~2.0)×10~(-6)kg/s条件下,通过对反应过程中镍纳米粒子的包覆温度和前驱体二茂镍(NiCp_2)供给速率调控可对镍纳米粒子的粒径大小和包覆层数进行调控.结合实验结果,分析了载体氢气对二茂镍反应的催化促进作用,阐述了旋转化学气相沉积条件下Ni纳米粒子在Al_2O_3粉体表面均匀包覆的过程与机制.通过调控包覆温度和原料供应速率,可以影响前驱体二茂镍的分解行为,从而调控镍纳米粒子在Al_2O_3粉体表面的包覆状态.     

北京研制成功纳米铝粉包覆复合系列涂层材料

据相关媒体报导，北京矿冶研究总院在开发出“纳米铝粉包覆的复合型镍铝涂层材料”之后，近日又研制成功了“纳米铝粉包覆的复合型系列涂层材料”。该系列涂层材料包括双组分中间化合物镍铝、三组分化合物镍铬铝、多组分化合物镍铬铝钴氧化钇、铁铬镍铝碳化钨等耐磨、耐蚀和耐高温的面层和底层材料，其性能明显优于国外同类产品，而成本却显著低于后者。     

镍、钴和铜包覆型复合粉末的制备与应用现状

简要评述了镍、钴和铜包覆型复合粉末的主要制备方法及其优缺点,概述了镍、钴和铜包覆型复合粉末的应用现状及其进展.     

Effect of activators on the properties of nickel coated diamond composite powders

Nickel coated diamond composite powders were fabricated via a newly developed direct electrodeposition technique. The effects of activators on the coating of diamond were firstly investigated and diamond grinding wheels were then prepared from Ni-coated diamond composite powders with different activators. The microstructural characterizations of this composite powders were finally conducted by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction, and the mechanical and tribological properties of as-prepared diamond grinding wheels were also measured. There are changes in microstructures and properties of the composite powders with activators. The activator concentration also has an influence on the morphologies and phase structures of the Ni coating on diamond particles.The composite powders with more compact coating of nickel can be prepared by adding 1 g dm~(-3) or more AgNO_3 as an activator to electrodeposit nickel on diamond. The mechanical and tribological properties of diamond grinding wheels were significantly improved when the coating phase structure of Ni crystal grew with(111) plane orientation on the surface of diamond particles. The wheels made from nickel coated diamond composite powders possessed the advantages of easy preparation and outstanding tribological properties. Therefore, Ni coated diamond composite powders exhibit a great potential to be extensively applied in diamond cutting and grinding tools.     

Ag包覆Fe3O4复合粉体的制备及其性能研究

用化学镀法,甲醛为还原剂,制备Fe3O4/Ag包覆复合粉体.用XRD、SEM和EDX对粉体进行表征.用重法测定粉体的抗氧化性能,并研究了AgNO3用量对Fe3O4/Ag包覆复合粉体的导电性能的影响.结果表明,用该法制备的Fe3O4/Ag包覆复合粉体能够实现表面银层包覆完整;Fe3O4粉镀银后的抗氧化性能得到一定程度的提高;AgNO3用量越多,Fe3O4/Ag包覆复合粉体的导电性能越好.     

矿物颗粒表面纳米化修饰及其在PP复合材料中的应用

通过化学方法成功地实现了矿物粉体在Ca (OH)₂-H₂O-CO₂ 体系中的表面纳米化修饰, 即在微米级重质碳酸钙、硅灰石粉体表面形核生成粒径均匀的纳米碳酸钙颗粒层。研究表明, 表面纳米化修饰后的矿物粉体表面的粗糙度大大增加, 尖锐的棱角得以钝化, 纳米化修饰后矿物粉体比表面积比原来提高至少200 %以上。将经表面纳米化修饰后的硅灰石粉体在聚丙烯(PP) 中填充应用, 较未经表面纳米化修饰的硅灰石粉体填料, 其抗冲击强度提高65 %以上, 延伸率提高200 %以上。     

化学镀法制备纳米Cu/Al复合粉末

为了改善超细铝粉的表面易氧化问题和微米级铝粉对推进剂的热分解催化作用不明显现象,以对推进剂具有良好催化作用的纳米Cu包覆金属Al表面.采用化学镀铜法对微米级铝粉表面进行镀覆,制备出纳米Cu粒子在超细Al颗粒表面包覆完整的Al-Cu核壳式复合粉末,并利用正交实验优化镀液组分及镀覆工艺条件.利用XRD、SEM、EDX等仪器,对复合粉末的形貌、物相结构及表面成分进行分析,结果表明铝粉表面包覆一层致密的纳米铜层,这种纳米层是由粒度约为18.83nm的晶态析出的纳米铜组成.     

热解炭(PyC)/BN复合粉的制备及其吸波性能

以尿素、硼酸和热解炭(PyC)粉为原料, 利用化学转化法, 在1750℃、N₂气氛下反应6 h, 制备了PyC/BN复合粉。采用XRD、XPS、SEM、DTA/TGA对PyC/BN复合粉的物相组成、化学成分、表面形貌及抗氧化性能进行了表征, 并用矢量网络分析仪测试了PyC/BN复合粉在2~18 GHz频段内的吸波性能。结果表明: 生成的h-BN颗粒在PyC粉表面形成包裹层, 其尺寸为几十至几百纳米。相比于PyC粉, PyC/BN复合粉的抗氧化性能明显提高, 在1200℃时其质量仍剩余50%以上, 而PyC粉在940℃时已被氧化完全。同时, 由于波阻抗增大, 电子位移极化、界面极化、多重散射和λ / 4干涉相消作用, 使得PyC/BN复合粉在相同厚度下(d=2 mm), 其反射率峰值达到-27.2 dB, 反射率小于-10 dB的频宽为2.6 GHz; 且随着厚度的增加, 其反射率峰值均小于-10 dB, 并出现多重吸收峰。PyC/BN复合粉可作为理想的轻质、耐高温、强吸收的吸波剂应用于微波领域。     

微胶囊铜粉对铜复合浆料性能的影响

为提高铜浆料的导电性,利用微胶囊技术在铜粉表面包覆液体石蜡,增强铜粉的抗氧化性,并添加少量导电性能优异的碳纳米管作为导电增强相,制备碳纳米管-铜复合浆料.利用四探针测试仪、扫描电镜等测试方法研究了液体石蜡含量对包覆铜粉性能的影响以及微胶囊铜粉作为主导电相,碳纳米管作为导电增强相对浆料导电性能的影响.结果表明:液体石蜡包覆含量为4 wt%的微胶囊铜粉具有良好的导电性和抗氧化性,其电导率为44.32%IACS;微胶囊铜粉作为碳纳米管-铜浆料的主导电相,制备浆料膜层电阻率为22.59 mΩ·cm,相比于未包覆的铜粉为主导电相制备的浆料膜层电阻率降低了12.44%;碳纳米管作为导电增强相所制备的浆料相比于纯铜浆料,电阻率降低31.74%.     

Preparation of Fe2O3/Al composite powders by homogeneous precipitation method

The Fe₂O₃/Al composite powders were prepared by homogeneous precipitation method. The influence of the concentration of Fe²⁺ and the molar ratio of raw materials on the preparation of Fe₂O₃/Al composite powders were investigated. X-ray diffractometer, scanning electron microscope, Fourier transform infrared spectroscopy and differential thermal analysis were used to analyze the morphology and structure of the Fe₂O₃/Al composite powders. The results show that the content of iron oxide in the composite powders could be effectively controlled by adjusting the concentration of Fe²⁺ and the molar ratio of raw materials in the plating solution. The surface of Al particle was coated with a layer of thick and dense iron oxide. The core-shell Fe₂O₃/Al composite powders with Fe₂O₃ content of 14.1% were produced, the coating efficiency of Fe₂O₃ reaches more than 77%. The iron oxide, which coated on the surface of the aluminium particle is flower-like cluster structure, each flower-like cluster is constituted by nano-flaky iron oxide.     

Electromagnetic properties of phosphate-coated ferrite composite materials

Sintered ferrite was treated with phosphoric acids to form phosphate-coated powders. The formation of the coating layer was verified by the improvement of oxidation resistance, microscopic morphologies, and evident reduction of conductivity of the powders. The coated powders were then blended with silicone to fabricate composite materials. The electromagnetic properties of the composites at the frequency range of 1?MHz to 1?GHz were investigated and found to be noticeably affected by the surface condition of the powders. The coating layer significantly reduced the imaginary part of permittivity of the composite owing to the improvement of insulation, while the resonance frequency was scarcely affected. The magnetization curves revealed that, compared to the composite containing as-prepared powder, the coated powder filled composites exhibited enhanced demagnetizing field, which consequently contributed to an obvious depression in magnetic permeability. Due to the modification of electromagnetic properties, the phosphate-coated ferrite composites were found to be practical materials as a substrate of radio frequency identification (RFID) metal tag. The impedance measurement results revealed that the phosphate-coated ferrite composites could remedy destructive interference imposed by metal and was beneficial for fabrication of RFID metal tag.     

An approach to prepare uniform graphene oxide/aluminum composite powders by simple electrostatic interaction in water/alcohol solution

The homogenous dispersion of graphene in Al powders is a key challenge that limits the development of graphene-reinforced metal matrix composites with high performance. Here, uniform distribution of graphene oxide (GO) coated on flake Al powders were obtained by a simply stirring and ultrasonic treatment in the water/alcohol solution. The effect of water volume content on the formation of GO/Al composite powders was investigated. The results showed that GO adsorbed with synchronous reduction on the surface of Al powders, but when the water content was higher than 80% in the solution, Al powders were totally changed into Al(OH)₃. With optimizing the water content of 60% in the solution, reduced GO was homogenously coated onto the surface of flake Al powders. The formation mechanism can be ascribed to the balance control between the liquid/solid interaction and the hydrolysis reaction.     

成型温度对多孔SiC陶瓷性能的影响

以包混工艺合成了核-壳结构的先驱体粉体,并引入少量Al<,2>O<,3>,SiO<,2>和Y<,2>O<,3>作为复合添加剂,通过模压成型、炭化和烧结工艺制备了多孔碳化硅陶瓷;研究了成型温度对样品的孔隙率、密度、热膨胀系数、抗弯强度和热震性能的影响.结果表明:成型温度对多孔碳化硅陶瓷的孔隙率、密度、抗弯强度及热震性能均...