非晶态Ni-Ce-P合金的共沉积与耐蚀性能

采用恒电位沉积、循环状安等方法研究了在水溶液中电沉积稀土合金的可能性 ,首次在含有CeCl3的弱酸性NaH2 PO2 镀液中获得了不同铈含量的Ni Ce P合金镀层 ,XPS、AES、XRD和SEM等实验技术表征了镀层的组成和结构 ,极化电阻和腐蚀电位的测试数据表明此镀层与Ni P无定形合金相比 ,具有更强的耐腐蚀能力 ,同时 ,讨论了沉积条件与镀层耐蚀性能的关系 ,结论是 :镀层中铈含量越高 ,其耐腐蚀性能越好 ,此外还对Ni Ce P的共沉积机理进行了初步探讨 ,指出在所研究的电沉积条件下 ,Ni Ce P合金共沉积可以用“诱导共沉积理论”合理解释     

化学沉积镍-铁-磷合金和它的伏安行为(英文)

在以次亚磷酸钠为还原剂 ,硼酸为缓冲剂和柠檬酸钠为络合剂的碱性介质中 ,研究了镍_铁_磷合金化学沉积条件 (pH值 ,温度及 [Fe2 + ]/([Ni2 + ]+[Fe2 + ])物质的量比 )对沉积速率和镀层组成的影响 ;并由此建立镀液稳定的最佳沉积工艺 .实验表明 ,镀液中硫酸亚铁对沉积镍_铁_磷合金有阻碍作用 (降低了化学沉积速率 ) ,造成镀层中铁含量不高 (小于 2 0 % ) ,使用循环伏安技术研究了镍_铁_磷合金的电沉积机理 .结果发现铁对次亚磷酸钠的氧化不起催化作用 ,提高镀液温度和pH值有增加沉积速率之效     

酸性溶液化学镀Ni-P-B合金及结构性能表征(英文)

联用次亚磷酸钠和硼氢化钠两种还原剂 ,从酸性镀液中沉积出不同硼含量的Ni_P_B镀层 ,并用原子力显微镜、X_射线衍射、透射电镜、动电位扫描等实验技术对其镀态结构及性能进行了表征。实验表明 ,镀液中硼氢化钠含量对沉积速度影响不大 ,但能显著影响镀层的化学组成。硼的共沉积使镍晶格点阵产生扭变 ,导致镀层晶粒增大 ,表面粗糙 ,颗粒分布不均匀 ,并使镀层由非晶态向微晶结构转变 ,且微晶成分随镀层中硼含量的增加而增多。Ni_P_B镀层的硬度随镀层中硼含量的增加而增大 ,热处理能显著提高镀层的硬度 ,且服从沉淀硬化机理。在 3.5wt%NaCl和 40wt%NaOH两种介质中 ,Ni_P_B合金的耐腐蚀能力优于Ni_P合金。镀层中硼含量越高 ,其耐腐蚀能力越强。     

稀土元素对镍基合金刷镀层沉积速率的作用

研究了La ,Ce ,Sm及Er对电刷镀Ni P ,Ni Cu P和Ni Cu P MoS2 3种镀层沉积速率的影响。4种稀土都能提高镀层的沉积速率 ,其中Sm对Ni P和Ni Cu P镀层沉积速率的提高效果最为明显。稀土提高镀层沉积速率均存在一最佳的加入量。在一定的刷镀电压范围内 ,稀土加速Ni P ,Ni Cu P镀层沉积速率的作用效果及程度没有变化。分析了稀土提高镀层沉积速率的作用机制。     

ICP–AES法测定金属钼中微量Fe,Ni

采用ICP–AES法测定金属钼中Fe,Ni含量,以盐酸–硝酸–氢氟酸溶解样品,试验了基体元素和共存元素对Fe,Ni的光谱干扰,Fe,Ni的分析谱线分别为238.204 nm,341.477 nm。测定Fe,Ni的线性范围均为0.001%~0.01%,线性相关系数分别为0.999 4,0 999 8,检出限分别为0.000 01%,0.000 04%。方法的加标回收率为95.7%~115.0%,测定结果的相对标准偏差为2.36%~17.82%(n=8)。该方法快速、简便,能够满足金属钼中含量范围为0.001%~0.01%的Fe,Ni元素的检测要求。     

电沉积条件对钴-锰合金结构和磁性能的影响

以柠檬酸为络合剂和硼酸为缓冲剂的酸性硫酸盐镀液中电沉积Co-Mn合金,循环伏安实验显示Co-Mn的起始共沉积电位约-1.282 V(vs.Hg-Hg2SO4 , sat.K2SO4)。借助扫描电镜(SEM)、能谱分析(EDS) 、X射线衍射(XRD)和振动样品磁强计(VSM) 研究了沉积条件对镀层结构和磁性能的影响。结果表明,Co-Mn镀层的组成受沉积条件影响较大;在镀液pH 4.0时,随着阴极电流密度从10 mA•cm-2增加到40 mA•cm-2,镀层中锰含量从0.3 at%增大到6.6 at%;镀层结构由hcp的固溶体转为fcc的固溶体;随着镀层中锰含量增加,膜的饱和磁化强度开始增大,然后降低,最大饱和磁化强度为1926.0 kA•m-1,膜的矫顽力在31.6 ~ 33.9 kA•m-1范围。     

Ni-P-CeO2化学复合镀层的XPS和AES分析

运用 SEM、AES和 XPS分析了 Ni- P- Ce O2 的镀层表面形貌及镀层组成。研究显示 ,Ni-P- Ce O2 镀层表面光滑、均匀、光洁度好 ,其相对原子摩尔分数分别为 Ni75.51 %、P1 3.37%、Ce2 .71 %、O6.81 %和 Fe1 .38%。镀层厚度为 6.0 μm,耐 1 0 0 g·L- 1 Na Cl溶液和 1 % (体积分数 ) H2 S气体的腐蚀能力较强。     

Cu含量对Ni-Cu-P化学镀层组织结构和性能影响

利用化学镀法制备出Ni-Cu-P合金镀层,研究了镀液中CuSO4·5H2O含量对合金镀层沉积速率和成分的影响. 通过XRD和SEM表征了不同CuSO4·5H2O质量浓度下Ni-Cu-P合金镀层的组织结构和表面形貌,运用极化曲线评价了合金镀层在质量分数为3.5%NaCl溶液中的耐蚀性能. 结果表明,随着镀液中CuSO4·5H2O质量浓度的增加,镀层沉积速率和P含量不断下降,Ni-P镀层中P的质量分数为14.98%. 当镀液中CuSO4·5H2O质量浓度为1.0 g/L时,P的质量分数为4.21%;镀层中Cu的含量随着镀液中CuSO4·5H2O含量的增加而增加. 当添加量为1.0 g/L时,镀层中Cu的质量分数达19.04%;镀层的结晶度随着Cu含量的上升不断增大,Cu的加入使镀层的表面形貌更加光滑;镀层的耐蚀性能随着镀液中CuSO4·5H2O含量的增加先上升后下降,当镀液中CuSO4·5H2O质量浓度为0.4 g/L时,Ni-Cu-P镀层表现出最优的耐蚀性能.     

超重力场电沉积NiW合金及其耐碱腐蚀性能

在超重力条件下电沉积NiW合金镀层,考察了超重力对NiW合金电沉积过程(各元素分电流、W含量和槽电压等)的影响规律;并利用扫描电子显微镜(SEM)、Tafel技术和电化学阻抗谱(EIS)技术研究了电沉积NiW合金镀层的表面形貌和在NaOH溶液中的抗腐蚀性能,同时通过浸泡实验考察了镀层的稳定性.结果发现,与常重力条件电沉积的NiW合金相比,超重力场电沉积的NiW合金中W含量增加,镀层表面无微裂纹产生;在10%(w)NaOH溶液中镀层自腐蚀电位正移,自腐蚀电流密度减小,腐蚀电阻也由常重力(重力系数G=1)时的865Ω·cm2增大至超重力(G=256)时的2305Ω·cm2;在10%NaOH溶液中浸泡144h后,超重力场电沉积的NiW合金表面无破碎和起皮现象发生.超重力技术在NiW合金电沉积过程中的应用,使镀层的耐碱腐蚀性能得到改善.     

大管径碳纳米管的可控制备

以乙醇为碳源,Ni-Fe/4(A)分子筛为催化剂,采用化学气相沉积法制备碳纳米管(CNTs).研究了反应温度和Ni/Fe摩尔比对CNTs管径的影响,反应温度对碳产率的影响.利用TEM和SEM观察CNTs形貌,结果显示,CNTs管径随着反应温度的升高和Ni/Fe摩尔比的降低而增大.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.