共查询到20条相似文献,搜索用时 46 毫秒
1.
氟元素是周期表中最活泼的非金属元素,有着最强的电负性,氟化物有着特殊的化学性能。关于氟化物在化学镀镍磷工艺中的应用已有报道,在镁基体上化学镀的前处理过程中,常用氢氟酸或氟化氢铵来进行活化处理;硅片表面上的化学镀也通常用HF与HNO3或HCl的混酸来活化,使硅片表面产生Si-H键。另外,如果在化学镀液中添加少量的氟化钠,则起到加速的作用[1]。对于氟化物在化学镀镍磷工艺中的报道仅限于此,未见有关氟化物在化学镀中其它作用的研究。鉴于此,本工作以氟化铵为研究对象,对其在弱碱性的条件下对化学镀液的缓冲能力、沉积速度以及所得镀层性能的影响进行了研究。 相似文献
2.
3.
4.
自组装膜吸附钯的化学镀前活化研究 总被引:9,自引:0,他引:9
提出了一种无需氯化亚锡敏化、基于分子自组装膜(SAMs)吸附钯的活化方法,成功地引发了在氧化铝粉末表面的化学镀铜.用XPS、AES、FTIR研究了钯的吸附机理,认为是由于氯化钯与SAMs上向外突出的氨基形成了化学键,并提出了相应的活化机理.金属化产物经XRD、FTIR、剖面金相显微表征分析与压片电阻率测定,示为金属铜完全包覆氧化铝的复合材料.该活化工艺具有活性引发层厚度薄、寿命长和与基底结合力强等优点,也可应用于其它表面富羟基的基底材料. 相似文献
5.
无电解镀共沉积钯银合金膜是纯化氢同位素最有发展前途的方法之一 .膜的制备技术有物理气相沉积法 [1 ]、化学气相沉积法 [2 ]、电镀 [3]和无电解镀法 [4]等 .无电解镀法使用设备简单、易于操作 ,而且可以均匀地沉积在形状复杂、硬度不同的基体上 .国内对电镀钯及有关钯银合金膜的研究 [5]较多 ,但无电解镀的研究甚少 .本文用无电解镀法制备含银量在摩尔分数2 3%~ 2 5 %的有支撑钯银膜 (膜厚为 3~ 5μm) .采用含有钯银两种离子的镀液制得的膜层 ,优于机械混合的均匀程度 .结果表明膜层没有合金化 .无电解镀条件为 :镀温 (5 0± 1 )℃ ,镀… 相似文献
6.
7.
陶瓷基钯银合金膜制备技术及性能研究 总被引:2,自引:0,他引:2
报道采用浆料涂敷与化学镀相结合法在陶瓷支撑上沉积钯银合金膜,采用浆料涂敷法,将含钯银的浆料涂敷在支撑体上,干燥后热分解,使支撑体表面沉积部分钯银。然后,采用化学镀在50℃下沉积钯银膜,热处理后,得到表面较光洁、厚度约为3μm、银含量为23%(原子百分含量)、合金化较完全的钯银合金膜,该膜在压差为0.1MPa,温度为300℃时的渗氢通量达45cm^3(STP)/(cm^2·min),分离因子达500,研究了钯银合金膜中银含量随热处理温度的变化规律,由实验结果发现,银逐渐向表面扩散,并在一定的温度条件达到基本平衡。 相似文献
8.
陶瓷基钯银合金膜制备技术及性能研究 总被引:1,自引:0,他引:1
报道采用浆料涂敷与化学镀相结合法在陶瓷支撑上沉积钯银合金膜,采用浆料涂敷法,将含钯银的浆料涂敷在支撑体上,干燥后热分解,使支撑体表面沉积部分钯银。然后,采用化学镀在50℃下沉积钯银膜,热处理后,得到表面较光洁、厚度约为3μm、银含量为23%(原子百分含量)、合金化较完全的钯银合金膜,该膜在压差为0.1MPa,温度为300℃时的渗氢通量达45cm^3(STP)/(cm^2·min),分离因子达500,研究了钯银合金膜中银含量随热处理温度的变化规律,由实验结果发现,银逐渐向表面扩散,并在一定的温度条件达到基本平衡。 相似文献
9.
探讨了碳纤维(CF)表面镍金属的化学镀工艺,制备了镀镍碳纤维(NiCF),采用密炼工艺制备了ABS基体复合材料,研究了CF和NiCF含量对复合材料的导电性能及电磁屏蔽效能的影响。结果表明:采用化学镀的方法在碳纤维表面镀覆了金属镍,所形成的镀层均匀致密;镀覆时间为5min时,镀镍后的碳纤维电阻率降低两个数量级;复合材料电阻率随CF、NiCF含量的增加而逐渐减小;复合材料电磁屏蔽效能随CF、NiCF含量的增加而逐渐增加,当NiCF含量为25%(wt)(约13.3vol%)时,电磁屏蔽效能最高可达51dB。 相似文献
10.
空心微珠表面化学镀Ni-Co-P合金 总被引:13,自引:0,他引:13
以无机非金属粉煤灰空心微珠为芯材, 利用化学镀工艺对其表面进行金属化改性, 可以得到表面完整包覆的导电粉体, 该粉体具有中空, 质轻, 粒度细, 高强度, 耐高温, 导电性能好等多种优异性能, 可部分代替金属和铁氧体微粉作为电磁波吸收剂. 采用SnCl2和PdCl2进行敏化-活化处理后, 在空心微珠表面化学包覆Ni-Co-P合金层, 利用XRD、EDS、SEM和镶嵌金相等方法对样品进行形貌观察和分析表征, 结果表明, 使用PdCl2作活化剂可以得到优质均匀的Ni-Co-P合金镀层, 镀层光亮, 均匀, 包覆完整. 化学镀后镀层呈非晶态, 450 ℃氢气气氛下热处理后出现结晶相Ni3P和六方晶系的α-Co单质. 相似文献
11.
Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
12.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
13.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
14.
Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
15.
In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献
16.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
17.
Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described. 相似文献
18.
用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在. 相似文献
19.
An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction. 相似文献
20.
The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed. 相似文献