空气中烧成镍电极浆料的研究

介绍了空气中烧成的Ni电极浆料的制备。讨论了浆料中玻璃粉、硼粉含量及烧渗工艺等对电极性能的影响。结果表明:浆料中Ni粉的纯度应为99.5%,粒度为500目;w(Ni)应不低于65%;玻璃粉的软化温度为450℃左右;粒度为300目,w(玻璃)为20%左右。加入硼粉系作为抗氧化剂。于810℃的大气中烧渗,保温5 min,此贱金属镍电极可牢固地附着在陶瓷基体上,并具有良好的欧姆接触性能。     

“开桶即用”特高温陶瓷金属化专用钨及其复合粉的开发

本文采用钨酸铵改性一热解一氢气还原一精细加工的工艺,制备了“开桶即用”特高温陶瓷金属化专用钨及w-Y2O3复合粉。改性后钨酸铵颗粒的费氏粒度为2.5μm,较改性前减小了超过一个数量级,且颗粒呈空心薄壁球形,该结构保证了钨粉形核、长大环境的高度一致,使粒度超细且高度均匀。在此基础上制备的w-Y2O3。复合粉中,絮状、纳米尺度的Y2O3较为均匀地包覆于超细钨粉颗粒表面。专用钨及其复合粉的开发有助于提高特高温陶瓷金属化产品的质量。     

共熔溶剂型镀镍及镍基复合镀层工艺研究

在氯化胆碱和乙二醇型深共熔溶剂中加入NiCl2·6H2O的电解液体系中,电沉积制备Ni镀层。分析了镀层的微观结构,研究了沉积电压和电解质浓度对镀层形貌和性能的影响。SEM显示,随着电压和Ni2+浓度的增加,镀层表面Ni颗粒变大,镀层变得粗糙,其腐蚀电位均比基底的腐蚀电位更负,起到了阳极保护作用。还初步研究了Ni/CNT的复合电沉积,发现CNT未能进入镀层,这有待进一步研究。     

电解法制备超细铜粉的工艺及性能研究

研究了电解液组成、工艺条件及阳极种类对电解铜粉粒度、产量、电流效率和电耗的影响,分析了电解法制备的超细铜粉的表面形貌和相结构.研究结果表明:极间距增大,铜粉粒度变粗,电流效率降低,电耗增加.混合酸浓度和电流密度提高,铜粉粒度变细,电流效率降低,电耗升高.电解液温度升高和刮粉周期增长,铜粉粒度变粗,电流效率提高,电耗降低;采用不溶性阳极进行电解时,能够有效地起到控制铜粉粒度的作用,但产量较低.     

室温固相化学法制备掺杂纳米氧化锌

为制备分散性良好的掺杂氧化锌纳米粉体,以硝酸锌、碳酸氢铵及掺杂离子的盐为原料,通过室温固相化学反应先制备出掺杂前驱物——碳酸盐。根据DSC-TGA分析结果,将其在275℃分解2h,得到掺杂氧化锌粉体。采用激光粒度分析、BET、XRD、SEM对产物的粒度、物相组成、颗粒形貌等进行了表征。结果表明:所制备的掺杂氧化锌粉体呈粒状,粒度分布均匀,晶粒度为52.35nm。     

Bi_2O_3对自燃烧法合成NiZnCu铁氧体的显微结构与性能的影响

以金属硝酸盐和柠檬酸为原料 ,应用溶胶 -凝胶法与自燃烧结合的方法制备了 Ni Zn Cu铁氧体微细粉。文章主要讨论了溶胶 -凝胶与自燃烧法结合制备 Ni Zn Cu铁氧体粉末的新方法 ,对 Bi2 O3掺杂的低温烧结 Ni Zn Cu铁氧体从烧结性质、结构与相组成、显微形貌、磁性质方面进行了研究 ,在此基础上分析了 Bi对材料形成过程和磁化机制的影响 ,并解释了掺杂量对材料磁性能的综合作用     

激光熔覆Ni基TiC强化复合涂层中内生TiC颗粒的生长机理

使用Ti粉、C(石墨)粉和Ni粉原位反应内生合成的方法,成功获得了Ni基内生TiC强化复合激光熔覆层.研究发现Ti、C含量对涂层中TiC的大小和形貌有较大的影响.偏晶反应是内生TiC颗粒出现核心的原因.     

电磁防护材料专题

题目：Fe3O4／Ni复合纳米颗粒的制备及其微波吸收特性 作者：哈日巴拉、付乌有、杨海滨、刘冰冰、邹广田 摘要：采用电爆炸技术,合成了粒径约为70nm的Ni纳米颗粒,以3-巯基丙基三甲氧基硅烷偶联剂（MPTS）对Ni颗粒进行表面改性,利用共沉淀法对改性Ni颗粒进行包覆得到核-壳结构的复合纳米颗粒。     

激光熔覆NbC/Ni60合金复合涂层的组织与性能

利用激光熔覆在45钢基体上制备了NbC颗粒增强的Ni60合金复合涂层。结果表明,复合涂层的组织由γ-Ni奥氏体枝晶、枝晶间的共晶、M₂₃C₆、NbC、和少量的CrB相等组成。NbC颗粒是在激光熔覆过程中原位合成的,其形貌为不规则的块状或花瓣状。原位合成NbC颗粒增强的Ni60合金激光熔覆涂层的显微硬度可达HV0.2 1 000左右,相比于纯Ni60合金涂层,复合涂层的显微硬度提高了约38%。并且,通过激光熔覆（Nb+C）/Ni60混合粉末成功修复了2Cr13材质汽蚀的汽轮机叶片。     

用于片式电阻浆料的二氧化钌粉的制备

以钌粉、硝酸钾、氢氧化钾为原料,水为反应介质,选用特定的还原剂和添加剂,利用液相化学还原沉淀法,并通过烘干和焙烧处理,得到了粒度分布较窄、分散性较好的二氧化钌粉,满足了片式电阻浆料的需要。采用干法激光粒度仪测试二氧化钌粉的粒度分布与平均粒径,用扫描电子显微镜(SEM)分析二氧化钌粉的形貌、粒径和团聚状态,用X射线衍射仪(XRD)检测粉体的晶相,并简要讨论了影响二氧化钌粉制备过程的各类因素。     

Fabrication of Nanocomposite Thermoelectric Materials by a Pulsed Laser Deposition Method

We applied a pulsed laser deposition (PLD) technique to fabricate nanocomposite half-Heusler thermoelectrics by employing two different methods: a dry process and a wet process. First, we tried to obtain nanosized thermoelectric particles by using PLD in a liquid solvent. Nanosized (<100 nm) spherical and crystalline half-Heusler particles containing Ti, Zr, Hf, Ni, and Sn elements were obtained by this method, showing good controllability of stoichiometry. The key is to select a solvent that prevents oxidation. Second, the dry PLD process was employed to coat the thermoelectric powder with metal oxides. To this end, we developed a PLD coating apparatus. After sintering the coated powder using the spark plasma sintering (SPS) technique, we confirmed that a nanosized layer of the metal oxides was uniformly formed at the grain boundaries of the half-Heusler matrix. With these two examples, the capability of the PLD techniques to fabricate well-controlled nanocomposite thermoelectric materials is demonstrated.     

Improvement of Electrical Contact Between TE Material and Ni Electrode Interfaces by Application of a Buffer Layer

A single ??-structure thermoelectric (TE) module based on p-type NaCo₂O₄, n-type Mg₂Si, and Ni electrode was fabricated by the spark plasma sintering (SPS) method. The NaCo₂O₄ powder was synthesized by using a metal?Ccitric acid complex decomposition method. Bulk Mg₂Si prepared by melt quenching was ground into a powder and sieved to particle size of 75???m or less. To obtain a sintered body of NaCo₂O₄ or Mg₂Si, the powder was sintered using SPS. Pressed Ni powder or mixed powder consisting of Ni and SrRuO₃ powder was inserted between these materials and the Ni electrode in order to connect them, and electrical power was passed through the electrodes from the SPS equipment. The open-circuit voltage (V _OC) values of a single module in which TE materials were connected to the Ni electrodes by using pressed Ni powder was 82.7?mV, and the maximum output current (I _max) and maximum output power (P _max) were 212.4?mA and 6.65?mW at ??T?=?470?K, respectively. On the other hand, V _OC of a single module in which TE materials and an Ni electrode were connected with a mixed powder (Ni:SrRuO₃?=?6:4 volume fraction) was 109?mV, and I _max and P _max were 4034?mA and 109?mW at ??T?=?500?K, respectively. These results indicate that the resistance at the interface between the TE materials and the Ni electrode can be decreased and the output power can be increased by application of a buffer layer consisting of Ni and SrRuO₃.     

激光熔覆Ni60A W工艺与组织特征研究

利用2kW的CO2激光在A3钢表面熔覆Ni60A＋W混合粉末，获得外观质量良好的熔覆层。对熔覆层的组织观察和成分分析结果表明：W颗粒米发生溶解和熔化，并且为Ni60A中碳化物的形核和生长提供条件；当W含量较低时，W颗粒在熔覆层中分布均匀；而W的含量较高时，大的W颗粒向熔覆层底部聚集。加入的金属W颗粒的重量含量为10％时，所需比能较小。     

激光直接烧结成形金属零件的实验研究

分析了激光熔池的动态快速冷凝及“球化”效应机理，基于此采用激光烧结直接成形工艺对铁粉和Ni45合金粉末进行了一系列的激光烧结实验。结果表明,直接烧结单组元铁粉易出现翘曲变形和“球化效应”，成形质量不高，即使调整工艺参数获得多层烧结件，但致密度较低;而在基体上烧结Ni45合金粉末,在合适的工艺参数下获得了致密组织较好的多层烧结件，内部组织细密均匀，表面光滑平整，且与基体结合牢固。     

基于深度学习的3D打印球形粉末颗粒自动统计与测量

随着金属粉末3D打印技术的不断发展,如何从显微图像中准确提取粉末颗粒的粒形粒径和球化率信息变得越来越重要。文中基于深度学习算法Mask R-CNN,提出了一种电镜图像球形粉末颗粒自动统计与测量的方法。该方法可对单幅显微图像上超过1 000个颗粒进行自动识别,有效检测电镜图像中的遮挡颗粒,并且生成粒径分布、球形度和球化率统计结果。相比传统图像分割算法,颗粒识别准确度提升了23.6%。相比激光干涉仪的粒径分布测量结果,文中提出的方法可以将位于较大球形粉末上黏附的小颗粒也有效识别出来。     

两种粒径Fe79.7Ni2.5Si7.9B9.8非晶粉末的高频吸波性能

采用水雾化法制备了Fe79.7Ni2.5Si7.9B9.8非晶粉末,并通过筛分获得粒径不同的非晶合金粉末。研究不同粒径的非晶粉末在1~10 GHz频率范围内的介电性能和磁导率,同时计算不同粒径的非晶粉末的复合材料所对应的反射损耗。研究表明,粉末粒度以及试样厚度对非晶粉末材料的高频吸波性能有明显影响。     

Fracture origins of optical fibers fabricated by hybridized process

Fracture origins of single-mode optical fibers that were produced by the CIP hybridized process consisting of overcladding a VAD-derived core rod with silica glass made from commercial silica powder were studied. It was found that there were many inclusions that caused failure of the fiber at the screening test. To identify the inclusions, the EPMA technique was successfully used and new internal defects such as a Cr, a Cr-Fe, and a Zr inclusions were found. By investigating the manufacturing process precisely, stainless steel particles and Cr₂ O₃ particles in the silica powder were found to become origins of the fractures. Further, the removal of Cr₂O₃ particles by the reaction with chlorine gas at high temperature was studied, and its dependence on the reaction temperature and on the chlorine content was clarified. It was also suggested that the initial particle size of a Cr₂O₃ particle was an important factor for its elimination. The results obtained by this study should be used to remove both the Cr and the Cr-Fe inclusions     

SEM粉末样品的超声波制备方法研究

本试验利用扫描电子显微镜（SEM）、超声波清洗器等仪器研究了超声波法制备SEM粉末样品的方法,并解决了该方法存在的问题。试验结果表明：超声波法能够很好地分散粉末颗粒,但容易吸附水分,造成冷焊假象;修正超声波法是一种优良的SEM粉末样品制备方法,粉末分散均匀,没有堆积及冷焊假象,可用于研究粉末的形状、表面形貌及粉末的粒度分布。     

机械活化燃烧合成AlN-Al_2O_3复合陶瓷粉

在催化剂氯化铵的作用下,将高能球磨机械活化后的工业铝粉置于空气中自燃,制备出了AlN质量分数约为80%的AlN-Al2O3复合粉体。通过对原始铝粉和球磨铝粉的形貌进行对比分析,探讨了球磨对铝粉的机械力化学效应。借助XRD和扫描电镜分析了燃烧产物的物相、形貌和结构,结果表明,生成的AlN颗粒主要集中于燃烧产物中心部,粒径为2μm;生成的Al2O3颗粒则主要分布于燃烧产物外表面,粒径为100nm。