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制备了N-二异辛基-2-苯并噻唑次磺酰胺(DIMB)和2-硫酮-苯并噻唑-3-甲基鄄巯基乙酸异辛酯(MBES)两种含氮杂环抗磨添加剂, 用SRV型高温摩擦磨损试验机评价它们在芋类基础油中的抗磨减摩性能, 对它们在不同条件下形成的摩擦膜进行X射线吸收精细结构光谱(XANES)分析, 用原子力显微镜(AFM)分析摩擦膜的表面形貌. 结果表明, 添加剂DIMB和MBES具有很好的抗磨性能, 但没有减摩性能. XANES分析结果表明, 添加剂MBES形成的摩擦膜完全由硫酸亚铁组成, 而添加剂DIMB形成的摩擦膜的次表面和本体主要由二硫化铁组成, 未测量到硫酸盐或硫化铁, 但摩擦膜表面部分被氧化成硫酸亚铁. AFM 测试结果表明, 与含1.5%(w)二烷基二硫代磷酸锌(ZDDP)抗磨添加剂的钢块磨损表面相比较, 分别含1.5%(w)DIMB 和1.5%(w)MBES添加剂的钢块磨损表面出现了深而宽的“犁沟”. 相似文献
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以精制菜籽油为原料,天然丝光沸石为催化剂,研究了硫化菜籽油的催化合成,并借助FTIR测试技术分析了产物的化学结构. 通过四球摩擦磨损试验机考察了其摩擦学性能,同时对磨痕表面进行了XPS及显微分析,探讨了其润滑机理. 结果表明,随硫粉投料量的增大,菜籽油不饱和度逐渐降低,在丝光沸石催化下,硫化反应收率可达98%以上;含硫量从0增大到9.96%,硫化菜籽油的摩擦学性能明显提升,摩擦系数由0.085降为0.025,磨斑直径由0.56 mm降至0.42 mm,最大无卡咬负荷(PB值)由549 N升至745 N,烧结负荷(PD值)由1 960 N升至2 254 N;其润滑机理初步归结于硫化菜籽油在摩擦副表面上形成的吸附油膜,以及摩擦过程中由于摩擦化学反应形成的摩擦转移膜共同起减摩耐磨和极压作用. 相似文献
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设计合成了2种香豆素取代二乙炔单体,7-(10,12-二十三双炔酰氧基)-香豆素(CODA)和7-(10,12-二十三双炔酰氧乙氧基)-香豆素(CO2DA),研究了柔性间隔基对香豆素取代二乙炔单体在气-液界面的组装、单体LB膜的聚合以及聚二乙炔主链螺旋结构形成的影响.利用Langmui-Blodgett(LB)技术,以纯水为亚相,膜压在35 mN/m时沉积制备了香豆素取代二乙炔单体LB膜.尽管CODA是非手性的,但其LB膜均表现出明显的宏观手性信号.这是由于在压缩过程中香豆素基团间强烈的π-π堆积,形成了螺旋排列,显示出超分子手性.而CO2DA LB膜无明显CD信号.经254 nm紫外光辐照,CODA LB膜聚合成蓝相,聚二乙炔主链表现出明显的宏观手性.而CO2DA LB膜聚合后无明显的CD信号.薄膜中香豆素功能基团的不规则排列不利于二乙炔单体的固态聚合以及聚二乙炔主链螺旋结构的形成. 相似文献
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在润滑油复合添加剂中,特别是各种齿轮油复合剂和工业用油复合剂中,硫化异丁烯是一种应用极为广泛的功能性添加剂.它通过在摩擦表面生成沉积膜、反应膜或渗透层,能减缓摩擦表面的摩擦和磨损,具有优异的极压抗磨性.尽管硫化异丁烯的使用十分广泛,但由于它本身是一种含不同硫原子化合物的混合物,且常常与复杂的石油产品基体和其它添加剂共存,对它的分离分析有很大的难度.在多年的润滑油复合添加剂结构组成研究工作中,笔者一直感到对硫化异丁烯的分离鉴定缺乏得力的分析技术和手段,传统的分离、分析方法很难将其与其它添加剂进行有效的分离和鉴定. 相似文献
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通过静态失重法研究了十二烷基苯磺酸钠(SDBS)与六亚甲基四胺(HA)在盐酸溶液中对Q235钢的协同缓蚀效应, 并采用分子动力学模拟从缓蚀剂膜抑制腐蚀粒子扩散的角度对其缓蚀机理进行分析. 结果显示: SDBS和HA单独使用时, 最高缓蚀效率分别为82.82%和79.46%, 复配后最高缓蚀效率可达到92.78%; 与两种缓蚀剂单独使用时相比, SDBS与HA复配后缓蚀剂膜体系中的自由空间明显下降, 削弱了膜内缓蚀剂分子的自扩散能力, 腐蚀粒子在缓蚀剂膜携带下的被动迁移也随之减弱; SDBS与HA复配能更有效抑制腐蚀粒子在缓蚀剂膜中的扩散, 也就是说复配后的缓蚀剂具有更好的缓蚀性能. 相似文献
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采用溶剂热法制备了多种二维过渡金属硫化物(TMDCs), 在合成过程中通过调控反应前驱体的滴加速率来控制所得TMDCs的形貌和结构. 然后采用高温热处理来提高TMDCs的结晶性, 从而提升了其电催化活性. 在酸性电解液中进行电催化析氢性能测试. 结果表明, “花状”结构的金属性二维二硫化铌(NbS2)具有最佳的催化活性和稳定性, 在电流密度为10 mA/cm2时, 其过电位仅为146 mV, 持续工作24 h后电流密度几乎不衰减. 研究发现, 可充分暴露面内活性位点的“花状”结构以及高温处理后材料导电性的提高是二维NbS2具有优异电催化性能的主要因素. 相似文献
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The interaction of overbased salicylate detergents with zinc dialkyldithiophosphates(ZDDP)and its effect on the formation of tribofilms under boundary lubrication have been studied by means of X-ray absorption near-edge structure spectroscopy.The results show that addition of metallic detergents to neat ZDDP results in the change of surface chemistry of the tribofilm formed from neat ZDDP.Calcium from detergents is digested in the tribofilm.For the high overbased detergents,the deposit of overbasing agen... 相似文献
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制备了两种苯并噻唑衍生物2-苯并噻唑基-巯基硫代乙酸正辛酯(MBTT)和2-苯并噻唑基-巯基乙酸正辛酯(MBTA), 并用元素分析和核磁共振谱表征其分子结构. 用X光吸收近边结构谱(X-ray absorption near edge structure, XANES)全面地分析了杂环化合物在矿物油和菜籽油中所形成的摩擦膜和热膜的化学态. 分析结果表明, 在矿物油中, 添加剂MBTT和MBTA摩擦反应生成的摩擦膜主要由FeS2组成, 而菜籽油中, 两种添加剂摩擦反应生成的摩擦膜由FeSO4组成; 在两种基础油中, 两种添加剂生成的热膜都是由FeSO4组成的. 相似文献
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以合成的两种无灰型含磷/硫化合物为润滑添加剂, 以可生物降解的菜籽油作为基础油, 用四球机研究了体系的抗磨减摩性能, 以X射线光电子能谱(XPS)和X射线吸收精细结构光谱(XANES)对所形成的摩擦膜和热膜进行了表面分析, 并初步探讨了其润滑机理. 摩擦学研究结果表明, 两种含磷/硫化合物作为菜籽油的润滑添加剂时, 具有良好的抗磨减摩性能. XPS和XANES分析结果显示, 摩擦膜和热膜主要由吸附层和反应层组成; 在表面膜中, 磷主要以磷酸盐或焦磷酸盐等形式存在, 而硫主要以硫酸盐的形式存在. 研究结果还表明, 摩擦热在两种不同添加剂的摩擦膜形成过程中发挥着不同的作用. 相似文献
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Chen Z Xiao S Chen F Chen D Fang J Zhao M 《Journal of colloid and interface science》2011,359(1):56-67
The preparation and application of overbased nanodetergents with excess alkaline calcium carbonate is a good example of nanotechnology in practice. The phase transformation of calcium carbonate is of extensive concern since CaCO(3) serves both as an important industrial filling material and as the most abundant biomineral in nature. Industrially valuable overbased nanodetergents have been prepared based on calcium salts of heavy alkylbenzene sulfonate by a one-step process under ambient pressure, the carbonation reaction has been monitored by the instantaneous temperature changes and total base number (TBN). A number of analytical techniques such as TGA, DLS, SLS, TEM, FTIR, and XRD have been utilized to explore the carbonation reaction process and phase transformation mechanism of calcium carbonate. An enhanced understanding on the phase transformation of calcium carbonate involved in calcium sulfonate nanodetergents has been achieved and it has been unambiguously demonstrated that amorphous calcium carbonate (ACC) transforms into the vaterite polymorph rather than calcite, which would be of crucial importance for the preparation and quality control of lubricant additives and greases. Our results also show that a certain amount of residual Ca(OH)(2) prevents the phase transformation from ACC to crystalline polymorphs. Moreover, a vaterite nanodetergent has been prepared for the first time with low viscosity, high base number, and uniform particle size, nevertheless a notable improvement on its thermal stability is required for potential applications. 相似文献
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Haibing Ma Rui Qiao Yilin Li Huan Chen Tianhui Ren 《Surface and interface analysis : SIA》2009,41(10):779-784
Water‐based lubricants and metal‐working fluids are becoming more and more popular in modern manufacturing due to environmental concerns. Owing to the poor lubricating properties offered by pure water, additives are generally needed to improve the antiwear and extreme pressure properties. In the present work, the tribological behaviors of synthesized additives in water‐based lubricants are studied for different durations and temperatures by a four‐ball machine, and the worn surfaces were analyzed by scanning electron microscopy (SEM) and X‐ray absorption near‐edge structure (XANES) spectroscopy. It was found that the tribological properties changed with the duration and temperature, and the tribofilms mainly consisted of an adsorbed layer and a tribochemical layer. The compositions of tribofilms also changed with duration and temperature, and the different compositions of tribofilms would result in different tribological properties accordingly. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Temperature driven morphological changes of chemically precipitated hydroxyapatite nanoparticles 总被引:7,自引:0,他引:7
Kumar R Prakash KH Cheang P Khor KA 《Langmuir : the ACS journal of surfaces and colloids》2004,20(13):5196-5200
Hydroxyapatite (HA) is synthesized by a wet chemical route using calcium hydroxide and ortho-phosphoric acid at various temperatures (40, 80, and 100 degrees C). X-ray diffraction of the precipitate particles revealed HA as the predominant phase (>99%) with a small amount of beta-tricalcium phosphate. Fourier transform infrared spectroscopy indicated the presence of carbonate substitution, which decreased with increasing temperature. Transmission electron microscopy observations revealed needle-shaped particles with a high aspect ratio at 40 degrees C, which changed to spheroidal when the precipitation temperature was increased to 100 degrees C. The changes in the morphology with temperature were analyzed taking into account the driving force for the HA precipitation and the supersaturation level of Ca2+ and PO4(3-) ions with respect to HA. The analysis indicated that the supersaturation level of the reactants, especially the concentration of Ca2+ ions, played a predominant role on the precipitate morphology for this classical acid-base reaction. 相似文献
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Calcium carbonate has evoked interest owing to its use as a biomaterial, and for its potential in biomineralization. Three polymorphs of calcium carbonate, i.e. calcite, aragonite, and vaterite were synthesized. Three conventional bulk analysis techniques, Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and SEM, were used to confirm the crystal phase of each polymorphic calcium carbonate. Two surface analysis techniques, X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectroscopy (TOF‐SIMS), were used to differentiate the surfaces of these three polymorphs of calcium carbonate. XPS results clearly demonstrate that the surfaces of these three polymorphs are different as seen in the Ca(2p) and O(1s) core‐level spectra. The different atomic arrangement in the crystal lattice, which provides for a different chemical environment, can explain this surface difference. Principal component analysis (PCA) was used to analyze the TOF‐SIMS data. Three polymorphs of calcium carbonate cluster into three different groups by PCA scores. This suggests that surface analysis techniques are as powerful as conventional bulk analysis to discriminate calcium carbonate polymorphs. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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采用液相沉淀法,以硝酸铋[Bi(NO_3)_3]为添加剂来调控碳酸钙晶体的形状与大小,制备了海螺状碳酸钙粒子.通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)、热重分析仪(TGA)、原子荧光光谱仪(AFS)等对产物的结构和性能进行了表征.结果表明,在60℃条件下,添加20 mL浓度为2 g/L的Bi(NO_3)_3溶液可得到海螺状球霰石型碳酸钙粒子,且其荧光性明显增强.在碳酸钙的成核过程中,Bi~(3+)的加入起到了显著的调控作用. 相似文献
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Dauphin Y Cuif JP Salomé M Susini J Williams CT 《Analytical and bioanalytical chemistry》2006,386(6):1761-1771
The microstructure and composition of the layers of two giant avian eggshells were investigated using a combination of scanning
electron microscopy, electron probe microanalyses, and X-ray absorption near-edge structure spectroscopy (XANES). The two
species have some similarities and differences in their microstructure and composition; the composition is not homogeneous
throughout the eggshell thickness. XANES studies show that sulfur is associated with amino acids in the inner organic membranes,
whereas in the mineralised layers the sulfur is mainly associated with sulfated polysaccharides. These results are similar
to those obtained on chicken eggshells, and confirm the active role of sulfated acidic polysaccharides in biomineralisation
processes of carbonate skeletons. 相似文献
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Kralj D Kontrec J Brecević L Falini G Nöthig-Laslo V 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(7):1647-1656
Calcium carbonate was precipitated from calcium hydroxide and carbonic acid solutions at 25 degrees C, with and without addition of different magnesium (MgSO(4), Mg(NO(3))(2) and MgCl(2)) and sodium salts (Na(2)SO(4), NaNO(3) and NaCl) of identical anions, in order to study the mode of incorporation of magnesium and inorganic anions and their effect on the morphology of calcite crystals over a range of initial reactant concentrations and limited c(i)(Mg(2+))/c(i)(Ca(2+)) molar ratios. The morphology, crystal size distribution, composition, structure, and specific surface area of the precipitated crystals, as well as the mode of cation and anion incorporation into the calcite crystal lattice, were studied by a combination of optical and scanning electron microscopy (SEM), electronic counting, a multiple BET method, thermogravimetry, FT-IR spectroscopy, X-ray diffraction (XRD), and electron paramagnetic resonance (EPR) spectroscopy. In the systems of high initial relative supersaturation, precipitation of an amorphous precursor phase preceded the formation of calcite, whereas in those of lower supersaturation calcite was the first and only polymorphic modification of calcium carbonate that appeared in the system. The magnesium content in calcite increased with the magnesium concentration in solution and was correlated with the type of magnesium salt used. Mg incorporation caused the formation of crystals elongated along the calcite c axis and, in some cases, the appearance of new [011] faces. Polycrystalline aggregates were formed when the c(i)(Mg(2+))/c(i)(Ca(2+)) molar ratios in solution were increased. Addition of sulfate ions, alone, caused formation of spherical calcite polycrystalline aggregates. 相似文献