LY12铝合金铈化学转化膜的结构及耐蚀性研究

应用电化学方法及腐蚀试验研究了LY12铝合金表面常温稀土化学转化膜。结果表明，铝合金的稀土化学转化膜具有成膜温度低、速度较快、膜的耐蚀性能好等优点。电位－时间曲线表面，成膜动力学包括铝合金的溶解及随后的成膜两个过程。SEM表明，铝合金稀土化学转化膜的形态为片状，EDAX能谱表明转化膜主要由Ce,O,Al及少量的促进剂离子组成。腐蚀试验表明，未经处理的铝合金在3．5%NaCl溶液中经过21天浸泡后，表面出现了严重的点蚀，而经稀土处理的铝合金经过相同时间的浸泡后，表面只发生了轻微的均匀腐蚀，而未发生点蚀，浸泡后稀土处理的铝合金的失重较空白试样的下降了近1倍，铝合金的耐蚀性能大大提高。     

环境友好型铝合金表面转化膜的制备及其耐蚀性能

目前,电子电气中铝合金件的铬酸盐系化学转化处理溶液含有六价铬离子,严重污染环境.应用电化学方法在3A21铝合金表面制备了一种环保型化学转化膜,并用盐雾技术对其进行了研究.结果表明:这种化学转化膜常温下成膜速度快;致密的转化膜主要由冰晶石的细小颗粒组成;膜的耐蚀性能好.     

浅析铝合金汽车轮毂无铬钝化剂成膜机理

为了对铝合金汽车轮毂用无铬钝化成膜的成膜机理进行研究，采用电化学方法结合X射线光电子能谱(XPS)、原子力显微技术(AFM)研究铝合金汽车轮毂无铬化学转化膜的成膜作用及其成膜机理。结果表明，在化学转化膜的形成过程中，有机物和锆、氧化合物将竞争生长，成膜初期无机锆、氧化合物具有较快的反应成膜速度，随着成膜时间的延长，有机物组分硅烷、树脂慢慢形成化学键成膜，形成无机/有机完整连续体，从而起到更好的耐腐蚀协调作用。     

铝合金表面化学转化技术的研究进展

随着环保要求的不断提高,传统的含铬化学转化膜已不能满足工业生产的要求,开发新型无铬环保的铝合金转化处理技术,已成为研究热点。研究表明,以新型无机盐和稀土为成膜物质的化学转化膜具有优良的表面防护能力。综述了当前新型化学转化技术的研究现状,介绍了无机和稀土转化膜的研究进展,分析了转化膜的性能特点,指出了当前化学转化处理技术存在的问题,展望了化学转化技术的发展趋势,明确了无机盐及稀土的用量对转化膜性能的影响、转化液中辅助物质对转化膜的影响是今后研究的方向。     

铝合金钴盐无铬化学转化技术的发展现状及展望

传统的铝合金铬酸盐化学转化毒性大,对人体和环境有伤害。钴盐转化处理是一项无铬转化新技术,可以替代六价铬转化技术,应用前景广阔。介绍了钴盐无铬化学转化技术发展概况、成膜机理、工艺沿革、转化膜组成和结构,提出了新型钴盐无铬转化技术应在三价钴配体、协同金属离子、促进剂、水溶性有机物等方面进行深入研究,以优化槽液的使用性能,提高转化膜的耐腐蚀性和附着力。     

6061铝合金钛锆铈化学转化成膜过程及膜层的耐蚀性能

为进一步改善6061铝合金表面无铬化学转化膜的综合性能,以H2TiF6和H2ZrF6为主成膜剂,铈盐、偏磷酸盐等辅助成膜剂,制备了具有较高耐蚀性能的Ti-Zr-Ce化学转化膜。通过扫描电镜及能谱仪分析转化膜表面形貌及元素构成,并采用电子探针显微分析仪观察不同成膜阶段的铝合金微区结构的变化规律,研究了6061铝合金表面Ti-Zr-Ce化学转化成膜过程及膜层耐蚀性能。结果表明:膜层主要含有Al、O、Ti、P元素,还含有少量F、Zr元素,推测主要成分为TiO2,ZrO2,Al2O3及少量磷化物;极化曲线和交流阻抗测试表明Ti-Zr-Ce化学转化膜具有较好的耐蚀性能,反应时间为150s时制备的Ti-Zr-Ce转化膜试样的腐蚀电位为-0.577V,腐蚀电流密度较低,为0.115μA/cm^2.     

铝合金化学镀镍工艺研究

为改进铝合金化学镀镍工艺,避免浸锌对化学镀镍液的污染,研究了铝合金活化-预化学镀镍工艺.通过结合力、孔隙率和耐蚀性试验,确定了活化工艺最佳pH值为9～10,预化学镀镍最佳时间为4～5 min.结果表明,活化-预化学镀镍工艺可代替浸锌法,镀层质量达到GB/T13913-92技术要求,为铝合金镀镍提供了新的前处理技术.     

铝合金表面无铬导电转化膜的制备工艺

铬酸盐转化工艺严重污染环境,应用受限,新开发的常用转化技术的耐蚀、导电性不及铬酸盐,而且也未投入工业应用.以钼酸盐为主要成膜氧化剂,在溶液中添加氟化钠等成分,利用浸溃法在铝合金表面制备出了金黄色的钼酸盐导电转化膜.采用点滴法评价了转化膜的耐蚀性,借助四点测电阻法测试了膜层的导电性能,导电转化膜表面电阻约为3 mΩ·cm.通过化学导电转化膜形成过程的电位-时间曲线,探讨了化学成膜机理.结果表明:钼酸铵、氟化钠含量,溶液pH值、温度、处理时间等对转化膜的外观、性能影响明显.本工艺所制备的转化膜其耐蚀性、导电性基本符合工业应用要术.     

铝合金表面稀土转化膜工艺研究

为了全面取代铬酸盐，开发无污染铝合金防蚀处理新工艺，采用了正交试验得出以Ce(NO3)3为主盐的铝合金富铈转化膜工艺，膜的耐蚀性略高于铬酸盐处理膜，比铝合金的自然氧化膜耐蚀性高出约20倍，并以成膜均匀性、溶液稳定性和在0.1mol／L NaCl溶液中的极化阻力Rp为依据，研究了适合工业化应用的工艺范围，对几种富铈转化膜工艺进行了比较研究，结果表明，氧化剂的选择及其在溶液中的稳定性对成膜性能起重要作用。     

稀土氯化铈对铝合金铬酸盐转化膜成膜过程的影响

采用电化学测试系统和扫描电镜(SEM),分别研究了6061铝合金在氯化铈(CeCl3)浓度为0mg/L和40mg/L的铬酸盐处理液中的成膜过程及CeCl3对其成膜的作用。结果表明:有无CeCl3其成膜时间大致相同,但稀土氯化物的加入可以提高成膜电流,使成膜过程更加顺利;铬酸盐转化膜表面疏松多孔,存在很多裂纹,有的深入铝合金基体,加入氯化铈,膜更加均匀、致密,且裂纹有所减少。     

Chromium and zinc uptake by algae Gelidium and agar extraction algal waste: kinetics and equilibrium

Biosorption of chromium and zinc ions by an industrial algal waste, from agar extraction industry has been studied in a batch system. This biosorbent was compared with the algae Gelidium itself, which is the raw material for agar extraction, and the industrial waste immobilized with polyacrylonitrile (composite material). Langmuir and Langmuir-Freundlich equilibrium models describe well the equilibrium data. The parameters of Langmuir equilibrium model at pH 5.3 and 20 degrees C were for the algae, q(L)=18 mg Cr(III)g(-1) and 13 mgZn(II)g(-1), K(L) = 0.021l mg(-1)Cr(III) and 0.026l mg(-1) Zn(II); for the algal waste, q(L)=12 mgCr(III)g(-1) and 7mgZn(II)g(-1), K(L)=0.033lmg(-1) Cr(III) and 0.042l mg(-1) Zn(II); for the composite material, q(L) = 9 mgCr(III)g(-1) and 6 mgZn(II)g(-1), K(L)=0.032l mg(-1)Cr(III) and 0.034l mg(-1)Zn(II). The biosorbents exhibited a higher preference for Cr(III) ions and algae Gelidium is the best one. The pseudo-first-order Lagergren and pseudo-second-order models fitted well the kinetic data for the two metal ions. Kinetic constants and equilibrium uptake concentrations given by the pseudo-second-order model for an initial Cr(III) and Zn(II) concentration of approximately 100 mgl(-1), at pH 5.3 and 20 degrees C were k(2,ads)=0.04 g mg(-1)Cr(III)min(-1) and 0.07 g mg(-1)Zn(II)min(-1), q(eq)=11.9 mgCr(III)g(-1) and 9.5 mgZn(II)g(-1) for algae; k(2,ads)=0.17 g mg(-1)Cr(III)min(-1) and 0.19 g mg(-1)Zn(II)min(-1), q(eq)=8.3 mgCr(III)g(-1) and 5.6 mgZn(II)g(-1) for algal waste; k(2,ads)=0.01 g mg(-1)Cr(III)min(-1) and 0.18 g mg(-1)Zn(II)min(-1), q(eq)=8.0 mgCr(III)g(-1) and 4.4 mgZn(II)g(-1) for composite material. Biosorption was modelled using a batch adsorber mass transfer kinetic model, which successfully predicts Cr(III) and Zn(II) concentration profiles. The calculated average homogeneous diffusivities, D(h), were 4.2 x 10(-8), 8.3 x 10(-8) and 1.4 x 10(-8)cm(2)s(-1) for Cr(III) and 4.8 x 10(-8), 9.7 x 10(-8) and 6.2 x 10(-8)cm(2)s(-1) for Zn(II), respectively, for Gelidium, algal waste and composite material. The algal waste has the lower intraparticle resistance.     

Cobalt 1,3-Diisopropyl-1H-imidazol-2-ylidene Complexes: Synthesis, Solid-State Structures, and Quantum Chemistry Calculations

The reaction of (η(5)-C(5)H(5))Co(PPh(3))(2) with 1,3-bis(isopropyl)imidazol-2-ylidene (Im(i)Pr(2)) leads to the formation of (η(5)-C(5)H(5))Co(PPh(3))(Im(i)Pr(2)). In a similar fashion (η(5)-C(5)H(5))Co(Im(i)Pr(2))(CO) is formed from (η(5)-C(5)H(5))Co(CO)(2). The barrier to rotation about the Co-C(carbene) bond in the latter complex has been determined by variable-temperature (1)H NMR spectroscopy (13.6 kcal/mol) and by computation (13.3 kcal/mol). The structural and dynamic properties of (η(5)-C(5)H(5))Co(ImMe(2))(CO) (ImMe(2) = 1,3-dimethylimidazol-2-ylidene) and (η(5)-C(5)H(5))Co(ImAr(2))(CO) (ImAr(2) = 1,3-dimesityl-2-ylidene) were examined by quantum chemistry calculations.     

Mechanistic Investigation of Cycloreversion/Cycloaddition Reactions between Zirconocene Metallacycle Complexes and Unsaturated Organic Substrates

Treatment of the diazametallacycle Cp(2)Zr(N(t-Bu)C=N(SiMe(3))N(SiMe(3))) (4a) with diphenylacetylene resulted in the formation of the azametallacyclobutene Cp(2)Zr(N(t-Bu)C(Ph)=C(Ph)) (6a) and Me(3)SiN=C=NSiMe(3) in high yield. A kinetic study using UV-vis spectroscopy was carried out on the transformation. Saturation kinetic behavior was observed for the system, which is supportive of a mechanism that involves a reversible formal [2 + 2] retrocycloaddition of 4a to generate the transient imido species Cp(2)Zr=N-t-Bu (7a) and Me(3)-SiN=C=NSiMe(3). Trapping 7a with diphenylacetylene in an overall [2 + 2] cycloaddition reaction affords zirconacycle 6a. The study of cycloreversion/cycloaddition reactions between diazametallacycle complexes and diphenylacetylene was extended to other zirconocene systems. Detailed kinetic studies were performed for the exchange reactions between the diazametallacycle complexes Cp(2)Zr(N(2,6-Me(2)Ph)C=N(SiMe(3))N(SiMe(3))) (8a) and Cp(2)Zr-(N(2,6-Me(2)Ph)C=N(t-Bu)N(t-Bu)) (8b) with diphenylacetylene (5a) to give the corresponding azametallacyclobutene complex Cp(2)Zr(N(2,6-Me(2)Ph)C(Ph)=C(Ph)) (6c) and extruded carbodiimides (Me(3)SiN=C=NSiMe(3) for 8a and (t-Bu)N=C=N(t-Bu) for 8b). For both systems, the reactions were found to be first order in metallacycle and zero order in alkyne. Treatment of the diazametallacycle complexes Cp(2)Zr(N(2,6-i-Pr(2)Ph)C=N(Cyc)N(Cyc)) (9a) and Cp(2)Zr-(N(2,6-i-Pr(2)Ph)C=N(i-Pr(2))N(i-Pr(2))) (9b) with alkyne 5a resulted in the formation of the six-membered zirconacycles 10a,b, respectively, upon heating at 75 degrees C. The products 10a,b are generated from the overall insertion of alkyne 5a into the nitrogen-carbon bond of the zirconium-containing diazacyclobutane. Complex 10a has been characterized by an X-ray crystallographic study. When the azacyclobutene Cp(2)Zr(N(2,6-i-Pr(2)Ph)C(Ph)=C(Ph)) (6e) was treated with CycN=C=NCyc or (i-Pr)N=C=N(i-Pr), the same six-membered zirconacycle complexes 10a,b were obtained. Kinetic analysis of the reaction of 6e and (i-Pr)N=C=N(i-Pr) to yield 10b supports an associative process wherein alkyne 5a directly inserts into the zirconium-carbon bond of 6e. The diazametallacycle complex 4a underwent a stoichiometric metathetical exchange with symmetrical carbodiimides RN=C=NR (R = p-Tol, m-Tol, i-Pr, Cyc) to generate new cyclic zirconocene complexes and Me(3)SiN=C=NSiMe(3). Kinetic studies were carried out on the exchange reaction between 4a and (m-Tol)N=C=N(m-Tol) to form 4e and Me(3)SiN=C=NSiMe(3). The experimental rate data obtained are consistent with a dissociative mechanism. Additionally, the saturation rate constant derived for this system from the data is the same (within experimental error) as the saturation rate constant obtained from the kinetic study of 4a and diphenylacetylene to form 6a and Me(3)SiN=C=NSiMe(3). These findings provide additional support for a dissociative mechanistic pathway in the exchange reactions, since the rate constant in the formal [2 + 2] retrocycloaddition reaction to generate imidozirconocene species Cp(2)Zr=N-t-Bu (7a) and Me(3)SiN=C=NSiMe(3) should be the same for both reactions.     

Physical and chemical modification of distillery sludge for Pb(II) biosorption

The waste distillery sludge from sugar-cane industry was pretreated physically (boiled, heated and autoclaved) as well as chemically (HCl, H(2)SO(4), H(3)PO(4), NaOH, Ca(OH)(2), Al(OH)(3), C(6)H(6), HCHO, CH(3)OH and C1(2)H(25)OSO(3)Na (sodium dodecyl sulphate (SDS)) for assessing the comparative sorption capacity of untreated and modified distillery sludge for Pb(II) biosorption from aqueous solutions. Experiments were conducted in shake flasks on a batch basis to access the effect of different experimental parameters such as pH, biosorbent dosage, biosorbent size, initial Pb(II) concentration and contact time. The uptake capacity 'q' (mg/g) of untreated and pretreated distillery sludge was in following order: NaOH (51.29+/-1.21)>HCl (49.82+/-1.22)>HCHO (49.56+/-1.14)>H(2)SO(4) (47.71+/-1.20)>HgCl(2) (45.32+/-1.06)>Ca(OH)(2) (44.01+/-1.18)>MeOH (43.73+/-1.23)>C(6)H(6) (42.72+/-1.19)>H(3)PO(4) (42.01+/-1.17)>SDS (40.87+/-1.27)>autoclaved (40.23+/-1.24)>Boiled (39.95+/-1.19)>heated (38.87+/-1.32)>Al (OH)(3) (38.30+/-1.14)>untreated (37.76+/-1.21). In further parameter studies, the optimized biosorbent size was 0.250 mm at pH 5 and best dose was 0.05 g of biosorbent. The applicability of the Langmuir and Freundlich models for sorption process was tested and best fitted model was Langmuir with the coefficient of determination (R(2)) value, 0.97, the process followed second order kinetic mechanism.     

Transmitted-light microscopy - a new method for surface structure analysis of cleanable non-woven dust filter media

A series of CeO(2)-ZrO(2) mixed oxides were prepared using coprecipitation method and characterized by BET, oxygen storage capacity (OSC), X-ray diffraction (XRD) and H(2)-temperature-programmed reduction (H(2)-TPR). The catalytic activities toward toluene combustion were investigated in a micro-reactor. The results demonstrate that the catalytic activity of Pt/gamma-Al(2)O(3)/Ce(0.50)Zr(0.50)O(2) monolithic catalyst can be greatly improved by doping metal into Ce(0.50)Zr(0.50)O(2). When doping Y and Mn into Ce(0.50)Zr(0.50)O(2) simultaneously, the catalyst Pt/gamma-Al(2)O(3)/Ce(0.40)Zr(0.40)Y(0.10)Mn(0.10)O(X) shows the highest activity. The T(10) (the temperature of 10% toluene conversion) and the complete conversion temperature (the temperature of 90% toluene conversion) of toluene are 443 and 489K, respectively. Gas hourly space velocity (GHSV) results show that the prepared catalyst can be applied in a wide range of GHSV (from 12,000 to 20,000h(-1)). The catalyst prepared shows great potential for practical application.     

Kinetics of Fe(3)O(4)-CoO/Al(2)O(3) catalytic ozonation of the herbicide 2-(2,4-dichlorophenoxy) propionic acid

The presence of Fe(3)O(4)-CoO/Al(2)O(3) can improve degradation efficiency significantly during the ozonation of the herbicide 2-(2,4-dichlorophenoxy) propionic acid (2,4-DP). The main factors affecting degradation efficiency, such as pH, the catalyst concentration and addition of the scavenger, were investigated. The kinetics of the catalytic ozonation are also discussed. The results indicate that two factors, the oxidation after adsorption of 2,4-DP and the oxidation of hydroxyl radicals (OH), lead to a great enhancement in ozonation efficiency during the catalytic ozonation of 2,4-DP in the presence of Fe(3)O(4)-CoO/Al(2)O(3), in which the oxidation of the OH plays an important role. Under controlled conditions, the apparent reaction rate constants for the degradation of 2,4-DP were determined to be 2.567 × 10(-4)s(-1) for O(3) and 1.840 × 10(-3)s(-1) for O(3)/Fe(3)O(4)-CoO/Al(2)O(3). The results from the analysis of the reaction kinetics using the relative method showed that O(3)/Fe(3)O(4)-CoO/Al(2)O(3) possessed a larger R(ct) (R(ct) is defined as the ratio of the ·OH exposure to the O(3) exposure, R(ct) = ∫C(t)(OH) dt/C(t)O(3)dt) than O(3), indicating that O(3)/Fe(3)O(4)-CoO/Al(2)O(3) produced more hydroxyl radicals.     

Role of late transition metals on pitting resistance of Zr-Ti-(Cu,Ni,Co)-Al bulk metallic glasses in 0.6 M NaCl aqueous solution

Four quanternary Zr-based bulk metallic glasses(BMGs)were selected,including the Zr_(46)Ti_2Cu_(45)Al_7,Zr_(61)Ti_2Cu_(25)Al_(12),Zr_(55)Ti_4Ni_(22)Al_(19)and Zr_(55)Ti_2Co_(28)Al_(15),due to their robust glass-forming ability and containing a single species of late transition metal(LTM)in compositions.Their pitting resistances in 0.6 M Na Cl aqueous solution were investigated to examine the role of LTM elements in the alloys,with electrochemical measurements,surface morphology observation and x-ray photoelectron spectrometry analysis.It is shown that in comparision with two Cu-bearing BMGs,Zr_(55)Ti_4Ni_(22)Al_(19)and Zr_(55)Ti_2Co_(28)Al_(15)BMGs exhibited significantly superior resistance to pitting.Zr_(61)Ti_2Cu_(25)Al_(12),Zr_(55)Ti_4Ni_(22)Al_(19)and Zr_(55)Ti_2Co_(28)Al_(15)BMGs manifested distinct passivation behaviour,because of the formation of surface passive film mainly comprising of Zr O_2,Ti O_2and Al_2O_3.However,no significant differences in the electrochemical resistive properties and thicknesses of passive films were found between Zr_(61)Ti_2Cu_(25)Al_(12)and Zr_(55)Ti_4Ni_(22)Al_(19)BMGs.Nevertheless,at the passive film/metal interface,copper enrichment took place in Zr_(61)Ti_2Cu_(25)Al_(12),whereas the nickel was slightly deficient at the interface in Zr_(55)Ti_4Ni_(22)Al_(19).During pitting propagation,selective dissolution of the zirconium,titanium and aluminum over the copper took place in Zr_(61)Ti_2Cu_(25)Al_(12),but it was not the case in Zr_(55)Ti_4Ni_(22)Al_(19).For the two Cu-bearing BMGs,reduction of passive base metal elements in composition resulted in local selective dissolution,even absence of the passivation.     

Physicochemical characterization and Bioremediation perspective of textile effluent, dyes and metals by indigenous Bacteria

Physicochemical and bacteriological status of a local textile mill effluent showed considerably high values of temperature (40 degrees C), pH (9.50), EC (3.57mus/m), BOD (548mgl(-1)), COD (1632mgl(-1)), TSS (5496mgl(-1)), TDS (2512mgl(-1)), heavy metals ions (0.28-6.36mgl(-1)) and color above the prescribed fresh water limits. However, a considerable decline in almost all pollution indicators from source to sink indicated signs of natural remediation. Ten bacteria strains isolated from effluent showed comparatively higher resistance (MRL) (mgl(-1)) (average) for 10 heavy metals than against four structurally different dyes tested on solid media of mineral salt. Overall bacterial resistance was quite high against Fe(3+) (2820), Cr(3+) (1203), Zn(2+) (1122), Mn(2+) (804) and Pb(2+) (435), whereas, it varied amid 300-500 in four dyes. Bacterial decolorization/degradation of dyes indicated on solid media was confirmed through experiments carried out in liquid broth.     

Fabrication of novel luminor Y(2)O(3):Eu(3+)@SiO(2)@YVO(4):Eu(3+) with core/shell heteronanostructure

A novel polychromic phosphor with core-shell heteronanostructure has been prepared to improve the chromatic index of phosphors. As for the first example, Y(2)O(3):Eu(3+)@SiO(2)@YVO(4):Eu(3+), its synthetic route, structure and optical properties are presented in this paper. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), energy-dispersive x-ray spectra (EDS) and photoluminescence (PL) were all employed to characterize the composite core-shell phosphors. The XRD, FE-SEM and HR-TEM results indicate that the SiO(2) and YVO(4):Eu(3+) layers have been successfully coated on Y(2)O(3):Eu(3+) nanoparticles and SiO(2) layer, respectively: these layers were further verified by the EDS. The PL showed that the red-emitting phosphor Y(2)O(3):Eu(3+)@SiO(2)@YVO(4):Eu(3+) possessed the independent luminescent properties of both the core Y(2)O(3):Eu(3+) and the shell YVO(4):Eu(3+). The emissions were dominated by [Formula: see text] or [Formula: see text] transitions of Eu(3+) when excited with different wavelengths. Since this broad-band response to excitation in the range of 225-340?nm gave more red/dark red emissions found at 612, 616 and 620?nm, the novel phosphor Y(2)O(3):Eu(3+)@SiO(2)@YVO(4):Eu(3+) could have potential biological labeling applications with wide flexibility.     

Reference wavelengths for strong lines of atomic hydrogen and deuterium

Wavelengths of the individual fine-structure components of the n = 1-2 (Ly(alpha)), n = 1-3 (Ly(beta)), n = 1-4 (Ly(gamma)), n = 1-5 (Ly(delta)), n = 1-6 (Ly(epsilon)), n = 1-7 (Ly(zeta)), n = 2-3 (H(alpha)), n = 2-4 (H(beta)), n = 2-5 (H(gamma)), n = 2-6 (H(delta)), and n = 2-7 (H(epsilon)) transitions of H and D are determined from theoretical values for the binding energies. Theoretical line strengths are used to obtain recommended values for the peaks of unresolved blends of these components as likely to be observed with discharge light sources and spectrometers with low to moderate resolution.