沉淀前驱物制备AIN陶瓷粉末

以硝酸铝和碳黑为原料，利用化学沉淀法制备出混合均匀的Al2O3＋C前驱物，并以该前驱物为原料采用碳热还原法制备了AIN粉末。研究了氮化反应温度、pH值、表面活性剂、溶液浓度、氮气流量和碳铝比等工艺参数对氮化反应的影响，得出的最佳工艺参数分别为：以0．4mol／L的硝酸铝溶液和比表面积为156m^2／g的碳黑为原料，控制原料中碳铝比为3：1，添加适量的硬脂酸（SA）和聚乙二醇（PEG）作为表面活性剂，控制沉淀过程中pH=9，通过共沉淀工艺得到分散性好、团聚程度小的前驱物，并将此前驱物在常压和氮气流量为5L／min的条件下于1550℃煅烧4h，最后将反应产物在650℃的空气中除碳4h，制备出氮含量为33．20％，氧含量为0．98％，比表面积为4．26m^2／g的AIN粉末。     

Preparation of ultrafine nickel powder by wet chemical process

1 Introduction Driven towards smaller size, higher capacitance and lower cost, the manufacturing techniques of multilayer ceramic capacitors(MLCCs) are now undergoing a revolution characterized by the development of MLCCs with base metal internal electrod…     

纳米镍基合金粉的超声波液相还原制备法

以次亚磷酸钠为还原剂，通过控制液相还原反应条件，从硫酸镍溶液中制备出纳米镍磷合金粉。研究了超声波功率、冷却方式、包覆剂用量等因素对镍磷合金粉的形貌、尺寸和分布以及包覆后的纳米镍磷合金粉的抗氧化性的影响。激光粒度分析仪分析表明粉末粒径分布均匀，中值粒径为50～65nm；TEM和XRD检测结果显示这种粉末粒子呈类球形，为非晶态结构。     

草酸镍纳米棒成型-分解-烧结制备亚微米多孔镍

以离子液相沉淀技术制备的草酸镍纳米棒为前驱体,采用成型-分解-烧结技术,在氩气气氛炉中,于360?C温度分解反应10分钟,然后分别于420,450,480和510℃温度条件下烧结反应10分钟,制备出具有亚微米级尺寸多孔结构的金属镍薄片。红外光谱分析表明前驱体为较纯的草酸镍粉体,X射线衍射谱分析表明制备的多孔镍薄片样品具有面心立方晶体结构,扫描电子显微镜和原子力显微镜分析表明金属镍薄片样品显现出烧结状的多孔结构,孔结构不规则、不均匀,孔洞尺寸的直径范围为100-1000纳米,孔壁是由直径约100-300纳米的纤维状金属镍构成。     

红土镍矿深度还原-磁选工艺富集镍和铁（英文）

提出采用"深度还原-磁选"工艺从红土镍矿中富集镍和铁。结果表明,在还原温度1275℃、还原时间50 min、渣相碱度1.0、配碳系数2.5和磁场强度72 kA/m的条件下,可得到镍品位为6.96%、回收率为94.06%和铁品位为34.74%、回收率为80.44%的镍铁精矿产品。分析表明,还原温度和时间影响深度还原发生的可能性及反应进度,渣相碱度影响炉料中渣的组成及镍铁元素从基体中溢出富集形成镍铁颗粒的速度,深度还原反应过程中镍铁颗粒生成、聚集并逐渐长大,经磁选后可有效促进镍铁矿物与脉石矿物分离。     

湿粉末法制备TaC涂层

本文通过在石墨基体涂覆前驱体料浆,在高温下烧结后得到TaC涂层。通过XRD和SEM对涂层形貌与结构进行表征,TaC涂层由平均尺寸为12μm的致密颗粒组成。涂层晶粒生长方式为自由取向生长,这种生长模式使得裂纹在扩展时会被钉扎在晶界连接处,而不会贯穿整个涂层。TaC涂层的硬度和弹性模量分别为15.35GPa 和 195.1GPa。     

球形氧化锆及氧化锆/镍复合粉体的制备

采用化学沉淀法分别制备球形氧化锆及镍/氧化锆复合微球粉体。考察加料速度、加料方式和反应器结构等因素对粒径分布、结晶状态及形貌的影响,初步得到优化工艺条件,并在优化条件下制得粒径分布均匀的球形氧化锆粉体和镍包裹氧化锆复合粉体。利用扫描电镜、能谱及X射线衍射仪分别对前驱体及热处理产物的形貌和物相进行分析,利用激光粒度分析仪检测球形氧化锆前驱体的粒径分布。研究表明,采用化学沉淀法,通过优化制备工艺条件,可以制备粒径分布较均匀的球形氧化锆粉体;利用非均相化学沉淀包裹技术制备的金属镍包裹氧化锆微球粉体,球形氧化锆颗粒表面作为异相成核的场所,通过控制颗粒浓度、加料速度以及添加表面活性剂等工艺条件,可以调控包裹层厚度、表面均匀度以及表面裂纹等。     

Preparation of fibrous nickel oxide particles

1　INTRODUCTIONThenickeloxide (abbreviatedasNiOthereafter)isaversatilematerialwhichhasbeenfoundmanyap plicationsinindustrialfields .Itisusedasthekeymaterialinmanufactureofbatteryelectrode ,cata lyst,thermalsensitiveelement ,gassensitiveele ment,functionalceramics ,glass ,electroniccompo nentsandsoon[18] .At present,theapproachesavailableforultrafineNiOparticlesproductionincludecarbonylmethod ,laserchemicalmethod ,pyrolysisbymicrowave ,sol gelmethod ,pyrolysisbyultrason ic ,precipitation …     

选择性还原-磁选回收镍渣中的有价金属

采用选择性还原-磁选工艺富集某镍渣中的镍、铜,通过控制还原过程参数实现选择性还原。结果表明：添加熔剂并适当提高渣料的碱度（CaO与SiO2质量比）有助于镍、铜的富集;对碱度0.15、还原温度1200℃、还原时间20 min、内配煤量5%（质量分数）的优化条件下得到的还原样品,通过磨矿-磁选获得镍、铜、铁品位分别为3.25%、1.20%、75.26%的精矿,镍、铜、铁的回收率分别为82.20%、80.00%、42.17%,实现了镍、铜相对于铁的选择性富集;选择性还原-磁选没有显著降低S、P的含量,两者在工艺过程中的行为需要进一步研究。     

添加剂氧化钙对镍渣强化还原的影响

针对铁以铁橄榄石形式存在而难以直接还原磁选回收的问题,采用在镍渣中配加CaO提升镍渣碳热还原速率及铁金属化率的技术思路。将添加剂与镍渣按比例混合并配加适量还原剂后,在高温炉中进行还原,结合热力学计算及产物特征分析结果,研究添加剂强化还原的机理及还原效果。结果表明:CaO的加入有效促进了硅酸铁的解离,强化了还原过程,还原速率加快,金属相在渣相中的形态结构发生改变,金属铁的聚集长大明显,有利于后续分离回收。随着CaO添加量由0增加到10%(质量分数),还原产物的金属化率和Fe颗粒平均粒径呈先增大后减小的趋势,FeO含量和残碳量变化规律相反。在CaO添加量为8%时,还原产物中铁的金属化率和粒径达到峰值,分别为87.25%和41.3μm。     

水合肼还原-重量法测定氯化浸金液中金含量

采用水合肼还原氯化浸金液(氯金酸溶液)中的金,称量析出海绵金的质量,实现了海绵金的准确测定,考查了反应温度、试液金浓度、水合肼使用量等对于测定结果的影响,并与其它测定方法进行了比对。调整氯化浸金液金浓度约为40 g/L,加入水合肼(用量1.5 mL/g-Au)还原后加热溶液微沸20 min,损失在滤液中的金量可忽略。测定结果的相对标准偏差(RSD)小于0.2%。方法操作简便,可满足生产分析的要求。     

沉淀转化-热分解法制备纤维状镍粉

以氯化镍、草酸铵和氨水为原料,通过沉淀转化制备纤维状前驱体。采用XRD、SEM、IR和 DTA/TGA分析手段研究前驱体粉末的成分与形貌。结果表明：在pH=8.4~8.8时得到的前驱体在形貌和成分等方面均不同于在 pH=6.0得到的前驱体,且两种条件下所得前驱体热分解的机理也不同。研究前驱体形貌、热分解气氛、温度及时间对镍粉形貌及分散性的影响,发现前驱体粉末在弱还原性气氛、温度为400~440°C下分解30 min时,最终产品基本保持前驱体的形貌。得到的纤维状镍粉分散性良好,但每根纤维表面不再光滑,而是具有大量微孔的粗糙形态。     

Study on Preparation Technology of Nickel Powder with Liquid Phase Reduction Method

采用液相还原法,以水合肼为还原剂,硫酸镍为原料,氢氧化钠为pH值调节剂,在不添加分散剂的情况下制备超细镍粉,并探究了体系反应温度、pH值、Ni2+离子浓度、N2H4·H2O/Ni2+摩尔比工艺参数对制备镍粉的平均粒径、形貌及分散性的影响。通过扫描电子显微镜(SEM)、X射线衍射(XED)、能谱分析、激光粒度分析等测试手段表征粉体的性质。得出了实验的较佳工艺参数:反应温度80℃、pH值为11、Ni2+离子浓度为0.5 mol/L,[N2H4·H2O]:[Ni2+]适宜范围为2~4,制得镍粉的平均粒径为400 nm。     

Synthesis of sub-micron nickel particles coated onto aluminum powders via a modified polyol process

Aluminum is commonly used as a fuel additive for propellants. The main limitations to its use lie in comparatively slow ignition and oxidation/combustion kinetics. Combustion performance of aluminized propellants can be improved through the use of Ni-coated Al particles. Sub-micron to nano-sized particles, with their increased reactivity, also improve combustion performance. Hence, in these contexts, fine Ni particles coated onto commercially available micron-sized Al powders using a modified polyol process were synthesized and evaluated. Ni-coated Al powders of various compositions produced by this method showed significant improvement in oxidation kinetics compared to untreated Al powders. The onset oxidation temperatures for the Ni-coated Al powders were found to be significantly reduced compared to pure untreated Al.     

真空碳热还原法制备碳化钛粉末

采用XRD、SEM、XRF以及激光粒度分析仪等分析手段,研究真空条件下碳热还原TiO2制备的碳化钛粉末。热力学计算和实验结果表明：真空条件下容易获得碳化钛,且随温度逐渐升高得到的产物顺序为：Magneli相（Ti4O7）、Ti3O5、Ti2O3、TiCxO1-x和TiC。当物料配比为1：3.2-1：6时,在1550℃保温4h的条件下可获得单相TiC粉末;物料配比为1：4和1：5时,产物粉末为标准化学计量的TiC1.0粉末;物料配比为1：4时,得到的产物为单相低杂质超细碳化钛粉末（D50为3.04μm）、SEM观察表明在产物块体表面存在分布均匀、团聚小、结构疏松的结构。     

Preparation of carbon nanotubes by ethanol catalytic combustion technique using nickel salt as catalyst precursor

A simple growth technique of carbon nanotubes （CNTs） by combustion of ethanol was developed. In the experiment, copper plate was employed as substrate, nickel nitrate （Ni（NO3）2） and nickel chloride （NiCl2） as catalyst precursor, and ethanol as carbon source. The cleaned copper substrate was dipped into catalyst precursor solution for mounting catalyst precursor particles. The dip-coated substrate was then placed into ethanol flame for about 10 min after drying. The black wool-like production grown on copper plate was obtained. This route is called an ethanol catalytic combustion（ECC） process. The black powders were characterized by means of scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, energy dispersive X-ray spectrometer（EDS） and Raman spectroscopy. The results show that the techique is much simpler and more economical to meet the future broader applications.     

Preparation of ferromagnetic binary alloy fine fibers by organic gel-thermal reduction process

Ferromagnetic metal fibers with a high aspect ratio （length/diameter） are attractive for use as high performance electromagnetic interference shielding materials. Ferromagnetic binary alloy fine fibers of iron-nickel, iron-cobalt and cobalt-nickel were prepared by the organic gel-thermal reduction process from the raw materials of critic acid and metal salts. These alloy fibers synthesized were featured with a diameter of about 1 pm and a length as long as 1 m. The structure, thermal decomposition process and morphologies of the gel precursors and fibers derived from thermal reduction of the gel precursors were characterized by FTIR, XRD, TG/DSC and SEM. The gel spinnability largely depends on the molecular structure of metal- carboxylates formed during the gel formation. The gel consisting of linear-type structural molecules shows good spinnability.     

氨络合物体系中杂质Zn~(2+)对电沉积镍的影响

通过霍尔槽试验研究氨络合物体系中杂质Zn~(2+)对镍电沉积的影响,采用电化学工作站测试不同Zn~(2+)浓度时的循环伏安曲线、稳态极化曲线及电流时间暂态曲线.结果表明:杂质Zn~(2+)的含量为0.1 g/L时,在小于2.78 A/dm的电流密度范围内可正常沉积出金属镍;杂质Zn~(2+)含量大于0.5 g/L时,在较大的电流密度范围内均无法正常沉积出金属镍;过电位小于640 mV时,Zn~(2+)的存在不影响阴极反应的传递系数,且不改变阴极反应机理;当过电位大于640 mV,且杂质Zn~(2+)的浓度大于0.5 g/L时,阴极反应的传递系数减小,阴极反应机理发生改变;杂质Zn~(2+)浓度大于0.5 g/L时,严重影响镍电结晶过程的成核速率,这是其抑制金属镍电沉积的主要原因.因此,采用镍氨络合物体系电积金属镍,应控制杂质Zn~(2+)的含量小于0.1 g/L.     

NaBH_4的水性还原法制备纳米铜颗粒(英文)

在碱性溶液中用NaBH4还原Cu2+制备纳米铜颗粒,研究NaBH4浓度和滴加速率对Cu纳米颗粒制备的影响。反应的最佳条件是:0.2mol/LCu2+,溶液pH12,温度313K,1%明胶作为分散剂,将0.4mol/LNaBH4溶液以50mL/min的速率加入CuSO4溶液中。氨水是最佳的络合剂。采用一系列实验研究不同时间点的反应进程。     

Preparation of basic nickel carbonate particles in solution system of Ni( Ⅱ )-NH3-CO2-3-H2O

Based on the principles of simultaneous equilibrium and mass balance, a series of thermodynamic equilibrium equations of Ni( Ⅱ )-NH3-CO2-3-H2O system at ambient temperature were deduced theoretically and the thermodynamic diagrams of lg[Ni]T versus pH at different solution compositions were drawn, which was quite effective to explain the formation mechanism of precipitation particles with different microscopic shapes. When pH of the solution is below 7.0, free nickel ions are dominant and when the precipitant is added, the fast coagulation will take place leading to the loose flocculation particles. While pH is above 7.0, because of the coordination of nickelion with ammonia, the precipitation proceeds slowly accompanying with the release of Ni2 from the multi-coordinated Ni(NH3)2 n (n= 1, 2, …, 6), which easily leads to the formation of the dense spherical particles.