钴—镍合金粉末的制取

目前以镍代钴或者部分代钴的研究已作了不少工作，而且也取得了一定的进展。日本住友金属株式会社研究出Co—Ni合金粉末的制造工艺。它是将钴离子溶液加入草酸水溶液中，在＜40℃的温度下反应生成草酸钴悬浊液，然后再加入镍离子溶液，同时保持上述温度，可生成柱状结晶沉淀物。洗涤、干澡沉淀物，在非氧化气氛中于400～700℃的温度下热分解沉淀物，可得到含Ni为30～95％的Co—Ni合金粉末。例如，将23．6升CoCl2溶液（Co170g／t）加入到100升的草酸水溶液中，草酸溶液的浓度应满足Co—Ni离子全部沉淀出来，制得悬浊液后，再加入3．1升N…     

利用钠-氨溶液制备纳米金属镍粉末及其表征

利用两步法制备得到纳米金属镍粉末。首先以氯化镍为原料在钠-氨溶液内通过还原-氮化反应制备得到纳米氮化镍粉末,然后通过真空热分解成功制备出纳米尺度的金属镍粉末。研究表明:钠-氨溶液内制备得到的纳米氮化镍粉末为六方结构,其平均晶粒尺度为19 nm;在300℃条件下进行真空热处理后,纳米氮化镍粉末完全分解,获得立方结构的纳米金属镍粉末,其平均晶粒尺度为21.4 nm,比表面积为30.5 m2·g-1;在300~700℃真空热处理过程中,纳米金属镍粉末的平均晶粒尺度增大为36.8 nm,比表面积减小为13.2 m2·g-1。     

草酸镍前驱体纤维微结构诱导制备多晶态纳米镍纤维的演化机理

在离子液相沉淀体系中,通过受限自组装生长可控制备草酸镍纳米纤维。在氩气环境中,在纤维微结构诱导下,通过热分解草酸镍纤维制备出镍纳米纤维。通过X射线衍射仪、扫描电镜和透射电镜等技术检测所得样品的性质。结果表明,氨的存在使草酸镍的生长习性从自由自组装模式转变为了受限自组装模式,制备的草酸镍纤维具有单斜晶体结构,直径100-200nm,长度为1-5μm。 热分解制备的镍纤维表面粗糙,具有面心立方晶体结构,直径100-200nm,长度为1-5μm。在草酸镍纤维形成的细而长空间的诱导作用下,镍原子经过成核、生长和聚合过程,从而形成纤维状纳米镍。     

草酸镍前驱体纤维微结构诱导制备多晶态纳米镍纤维的演化机理（英文）

在离子液相沉淀体系中,通过受限自组装生长可控制备草酸镍纳米纤维。在氩气环境中,在纤维微结构诱导下,通过热分解草酸镍纤维制备出镍纳米纤维。通过X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)等技术检测所得样品的性质。结果表明,氨的存在使草酸镍的生长习性从自由自组装模式转变为了受限自组装模式,制备的草酸镍纤维具有单斜晶体结构,直径100~200 nm,长度为1~5μm。热分解制备的镍纤维表面粗糙,具有面心立方晶体结构,直径100~200 nm,长度为1~5μm。在草酸镍纤维形成的细而长空间的诱导作用下,镍原子经过成核、生长和聚合过程,从而形成纤维状纳米镍。     

喷雾干燥法制备球形钨粉及还原过程的研究

以偏钨酸铵(AMT)为原料,采用喷雾干燥法结合氢气还原方法成功制备出球形钨粉。随后利用SEM、TEM、激光粒度分析仪和XRD等分析方法对粉末微观形貌、颗粒平均粒度、粒度分布和还原过程中的相变情况进行研究。结果表明,前驱粉末为球形,煅烧后,颗粒形貌未发生明显变化,仍保持球形;TEM结果显示粉末是球形中空结构。同时探讨了溶液浓度、鼓风速度、给料速度对粉末粒度的影响。激光粒度分析结果表明,溶液浓度对粉末的平均粒度影响最大,溶液浓度越大,颗粒的平均粒度就越大。粒度分布越集中,而给料速度对颗粒的平均粒度影响不明显。XRD结果显示,氢气气氛下,550℃保温2h,α-W相出现;还原温度升高到750℃,保温2h,WO3被完全还原为α-W。     

喷雾造粒-H_2还原制备WC-Co热喷涂粉末

以水溶性醋酸钴代替金属钴粉与WC粉、纯水、微量炭黑和有机碳球磨混匀,经喷雾造粒,H2还原制备WC-Co热喷涂粉。结果表明:当进风温度260℃、出风温度140℃、转速10000r/min所制备的粉末粒度在10~80μm,平均粒度为35μm。在1250℃下,H2还原WC-Co粉末接近共晶温度,产生大量液相,粉末合金化。中空球形颗粒,在重力作用下生成的液相开始流动,填充孔隙,使粉末颗粒密实、颗粒收缩、薄壁变厚,松装密度增大,粉末粒度在10~50μm、平均粒度为25μm,Co相均匀包覆球形WC颗粒。     

镍基高温合金沉淀强化的研究

镍基高温合金通过γ＇沉淀相强化,合金的性能和沉淀相的颗粒大小、分布、体积分数及粗化速率等因素有关。研究了镍基高温合金在750℃和850℃时效处理1000h,γ＇沉淀相的变化规律和对拉伸性能的影响。结果表明,沉淀强化γ＇相呈球形分散在γ基体上,随时效温度的升高,γ＇沉淀相微粒粗化,合金屈服强度降低。     

络合沉淀法制备球形WO_3-NiO复合粉末的研究

本文以硝酸镍、氨水和偏钨酸铵为原料,采用络合沉淀法制备了WO_3-NiO的前驱体,经煅烧得到WO3-Ni O复合粉,研究了反应过程中母液的pH值、反应时间及表面活性剂对前驱体及复合粉的成分、形貌和粒度的影响。结果表明:反应的pH值、反应时间及表面活性剂对复合粉的成分、形貌及粒度有很大影响。当p H值从7.5增大到8.5时,复合粉末中的球形颗粒比例逐渐减少,粉末D50由3.18μm增加到3.99μm,产物中的镍钨比由0.613增加到0.636;反应时间从90 min缩短到30 min时,粉末D50由3.88μm降低到1.74μm,比表面积由5.629 m~2/g升高至8.245 m~2/g,团聚程度和球形度均大幅降低;使用十二烷基硫酸钠作分散剂,能在防止颗粒的团聚长大的同时保持颗粒球形度。     

超细Cr_3C_2粉末的制备

将CrO3溶解于有机溶液中,通过喷雾干燥制得非晶态含铬的粉末前驱体,将前驱体粉末真空还原/碳化后得到超细Cr3C2粉末。采用X射线衍射仪﹑扫描电镜对工艺过程进行分析,分析结果表明:前驱体为10μm～20μm非晶态球形粉末,在真空中当温度升高到400℃时,前驱体粉末开始分解,生成微晶Cr2O3。当温度升高到550℃时,微晶Cr2O3迅速长大,前驱体粉末全部转变为Cr2O3与游离C原子级别混合均匀的复合粉末;温度升高到1150℃时得到碳化完全的Cr3C2粉末,粉末的一次颗粒粒度为0.5μm左右。     

纳米NiO/CNTs制备及其对镁合金组织性能的影响

以硫酸镍、氨水和CNTs为原料,采用直接沉淀法在CNTs沉积NiO,经450℃热分解得到NiO/CNTs材料,对所得试样进行了扫描电镜(SEM)、透射电镜(TEM)、X射线衍射分析(XRD)表征,并将其加入到镁合金中。结果表明,采用直接沉淀法制备的纳米NiO可以很好地附着在CNTs上。当NiO含量为33%时,NiO可以均匀地包覆CNTs,NiO颗粒尺寸平均为20nm,并且没有发生团聚,分散效果良好。与直接加入CNTs相比,包覆NiO的CNTs更容易加入镁合金基体中,使得晶粒更细小,硬度也相应更高。     

不同体系水热制备银氧化锡复合粉体的研究

分别采用氨水和柠檬酸作为溶液中银离子的配体,草酸、亚硫酸钠和柠檬酸作为还原剂,水热制备Ag-SnO2复合粉体。对Ag-SnO2复合粉体进行了差热分析、X射线衍射、扫描电镜和元素面扫描分析。结果表明:不同体系均可水热制备银氧化锡复合粉体。在以氨水为配体,分别以亚硫酸钠和草酸为还原剂的体系中,银和二氧化锡沉积完全。以亚硫酸钠为还原剂的体系中所得复合粉体为片状结构,厚度约为300nm,而以草酸为还原剂所得复合粉体为球形结构,粒径约为100nm。以柠檬酸为配合剂和还原剂的水热体系中二氧化锡沉积不完全,所得复合粉体为不规则球形,粒径较小,约为30nm。     

A study on comprehensive recycling of waste diamond tools

This article puts forward a new method of recycling materials in diamond tools comprehensively and efficiently by means of analyzing and summarizing various methods of recycling waste diamond tools.After the waste diamond tools were decomposed in a mixed acid,metals contained in it went into solution in their ionic forms,while diamond and tungsten carbide particles formed into residues to be reclaimed.The amounts of metal ions in the leaching solution were adjusted according to the contents of metals in the diamond tools;then,the leaching solution was co-precipitated using oxalic acid as precipitation agent,and ammonia water was added to adjust the pH value of the oxalic acid.Under the right conditions,the comprehensive precipitation rate of metals reached above 98%.Finally,ultrafine pre-alloy powder was obtained by hydrogen reduction of oxalate.     

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 …     

Thermodynamic analysis on preparation of fibrous NiO precursor powders with oxalate precipitation process

According to the principles of simultaneous equilibrium and mass balance, a series of thermodynamic equilibrium equations of Ni（ Ⅱ）-C2 O4^2--NH3-NH4^＋-H2O system at ambient temperature are deduced theoretically and the logarithm concentration versus pH value（lg[Ni^2＋ ]r-pH） diagrams at different solution compositions are drawn. The results show that when pH is above 8.0, nickel ions coordinate with ammonia, the precipitation proceeds slowly accompanying with the release of nickel ions from the multi-coordinated Ni（NH3）n^2＋ （n= 1, 2,…, 6） and the morphology of NiO powder precursor is fibrous; when pH is below 8.0, nickel ion directly reacts with C2O4^2- and the morphology of NiO powder precursor is of cubic-shape. Some experiments were made to confirm the relation between the total concentration of nickel ion and pH. It is shown that the thermodynamic mathematical model is correct and the calculated values are basically accurate.     

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…     

沉淀条件对钌粉粒度和形貌的影响

采用化学法制备高纯钌粉,研究了沉淀条件对制备的钌粉粒度和形貌的影响,对钌粉的纯度进行了分析。结果表明,氯气氧化作用对钌粉的粒度和形貌影响较大,在沉淀过程进行搅拌能有效细化氯钌酸铵晶粒。采用氯化铵饱和溶液沉淀,沉淀过程进行搅拌,并通入氯气进行氧化,得到(NH4)2Ru Cl6晶体,烘干后在800℃煅烧6 h,得到的钌氧化物在750℃条件下通氢还原30 min,得到的钌粉粒度约5~20μm,呈近球形的多边形,辉光放电质谱法(GDMS)分析表明钌粉纯度达到99.95%以上。     

Catalysts characteristics of Ni/YSZ core-shell according to plating conditions using electroless plating

This study aims to develop an anode catalyst for a solid oxide fuel cell (SOFC) using electroless nickel plating. We have proposed a new method for electroless plating of Ni metal on yttria-stabilized zirconia (YSZ) particles. We examine the uniformity of the Ni layer on the plated core-shell powder, in addition to the content of Ni and the reproducibility of the plating. We have also evaluated the carbon deposition rate and characteristics of the SOFC anode catalyst. To synthesize Ni-plated YSZ particles, the plated powder is heat-treated at 1200 °C. The resultant particles, which have an average size of 50 μm, were subsequently used in the experiment. The size of the Ni particles and the Ni content both increase with increasing plating temperature and plating time. The X-ray diffraction pattern reveals the growth of Ni particles. After heat-treatment, Ni is oxidized to NiO, leading to the co-existence of Ni and NiO; Ni₃P is also observed due to the presence of phosphorous in the plating solution. Following heat treatment for 1 h at 1200 °C, Ni is mostly oxidized to NiO. The carbon deposition rate of the reference YSZ powder is ~135%, while that of the Ni-plated YSZ is 1%-6%.     

采用草酸和紫外光催化法处理赤泥(英文)

利用草酸作为浸出剂以除去拜耳法残渣赤泥中的氧化铁,从而提高赤泥的工业应用价值,同时对草酸浸出液进行紫外光照射,将草酸铁还原成草酸亚铁沉淀,实现草酸溶液循环再利用。实验结果表明,在75°C下,赤泥在1mol/L草酸溶液中浸出2h,氧化铁的浸出率可达到96%,浸出后赤泥中氧化铁的含量由17.6%降低至小于1%。在紫外光照催化作用下,1h内浸出液中90%以上的草酸铁转变成草酸亚铁沉淀,剩余草酸可循环再利用。该草酸亚铁为β-FeC2O4.2H2O。对UV催化沉淀的机理进行讨论分析。     

Regeneration and decontamination of a nickel citrate complex in spent electroless nickel plating solutions

The possibility of citrate precipitation by excess metal ions in alkaline solutions suggests the use of Ni(II) together with OH^? to precipitate a Ni(II)-citrate complex from spent electroless plating solutions. After treatment of the precipitate with acid, excess Ni(II) can be removed in the form of insoluble Ni(OH)₂. The solution of the Ni(II)-citrate complex can then be reused for electroless nickel plating. During this procedure the additive adipate is not regenerated. For decontamination of spent electroless nickel plating solutions Fe(III) can be used as Ni(II)-citrate complex precipitant.     

Preparation of transparent yttrium aluminum garnet ceramics by relatively low temperature solid-state reaction

1　INTRODUCTIONYttriumaluminum garnet(YAG )isakindofcomplexoxideresultedfromthereactionofY2 O3andAl2 O3.ItschemicalformulaisY3Al5O12 .Ithasagarnetcrystalstructureandbelongstohexagonalsys tem .YAGceramicsholdpromiseforcertainopticalapplicationssuchashightemperaturewindowsusedtodetectinfraredwavesordevicesusedtorecordnu clearradiation .Becauseofitsthermalstability ,highhardness,physicalandchemicalstability ,andexcel lenttransparencyinawidewavelengthregionfromvisiblelighttoinfraredlight…