Corrosion inhibition of Al–bronze in acidified 4% NaCl solution

The synergistic effect between either benzotriazole (BTA) or thiourea (TU) and iodide ion are used to retard the dissolution of Al–bronze alloy in deaerated solution of acidified 4% NaCl of pH 1.8–2 at 60 °C; this is shown by the weight loss and polarization techniques. Iodide ion alone has no effect on the dissolution of the alloy but addition of 100 p.p.m. KI to 300 p.p.m. of both BTA and TU improved the inhibition efficiency to 92% and 78.8%, respectively, and also decreased the anodic current density in both media. This revised version was published online in November 2006 with corrections to the Cover Date.     

铜碲锂多元合金在3.5%NaCl溶液中腐蚀行为的研究

研究了铜碲锂多元合金中碲对合金耐腐蚀性的影响。经过25℃在 3.5% NaCl溶液中的全浸试验表明铜碲锂多元合金比纯铜具有更好的耐蚀性。利用扫描电镜观察腐蚀试样的表面形貌,发现表面不均匀的覆盖着一层多孔的腐蚀产物。经 X 射线衍射仪分析确定,该腐蚀产物为 Cu2 (OH)3Cl 和 Cu2O 的混合物。     

Corrosion of tin in citric acid solution and the effect of some inorganic anions

The corrosion behaviour of tin in different concentrations of citric acid solutions (0.3–1.0 M, pH=1.8) was studied at 30 °C by potentiodynamic technique. The E/I profiles exhibit an active passive behaviour. The active dissolution involves one anodic peak A associated with a dissolution of the metals as Sn(II) species. The passivity is due to the formation of thin film of SnO₂ and or Sn(OH)₄ on the anode surface. The cathodic sweep shows a small peak C related to the reduction of the passive film. The peak current density I_p of peak A increases with increasing both acid concentration and sweep rate.

The effects of adding increasing concentrations of Na₂CrO₄, NaMoO₄, NaNO₃ and NaNO₂ on the corrosion of tin in 0.5 M citric acid at 30 °C were investigated. Both CrO₄²⁻ and MoO₄²⁻ ions inhibit the corrosion of tin and the extent of inhibition enhances with their concentrations. Addition of either NO₃⁻ or NO₂⁻ accelerates the corrosion of tin. NO₃⁻ ions are more aggressive than NO₂⁻ ions.     

陶瓷超滤膜在柠檬酸生产中的应用研究

采用陶瓷超滤膜对柠檬酸浓缩液进行过滤,通过与预涂硅藻土(DE)的板框机过滤后的料液质量进行对比分析,结果表明此方法过滤后的产品质量同样得到改善,从而找出了一种新的提纯工艺.     

固体支撑液膜提取柠檬酸传质速率的研究

利用固体支撑液膜从水溶液中提取柠檬酸,研究了载体三正辛胺浓度对于支撑液膜体系传质渗透系数影响的规律,为该技术在柠檬酸清洁生产工艺的研究提供依据．     

Adsorption of copper ions from aqueous solution by citric acid modified soybean straw

The objectives of the present study were to convert soybean straw to a metal ion adsorbent and further to investigate the potential of using the adsorbent for the removal of Cu(2+) from aqueous solution. The soybean straw was water or base washed and citric acid (CA) modified to enhance its nature adsorption capacity. The morphological and chemical characteristics of the adsorbent were evaluated by spectroscopy and N(2)-adsorption techniques. The porous structure, as well as high amounts of introduced free carboxyl groups of CA modified soybean straw makes the adsorbent be good to retain Cu(2+). The adsorption capacities increased when the solution pH increased from 2 to 6 and reached the maximum value at pH 6 (0.64 mmol g(-1) for the base washed, CA modified soybean straw (CA-BWSS)). The Cu(2+) uptake increased and percentage adsorption of the Cu(2+) decreased with the increase in initial Cu(2+) concentration from 1 mM to 20 mM. Both the Langmuir and Freundlich adsorption isotherms were tested, and the Freundlich model fited much better than the Langmuir model. It was found that CA-BWSS have the highest adsorption capacity of the four kinds of pretreated soybean straw.     

高纯氧化铝陶瓷材料真空出气性能测试

通过一系列实验测试了致密型高纯氧化铝陶瓷(99瓷)的出气速率．考察了材质、不同预处理方法等因素对其出气性能的影响，并分析了不同温度下出气的主要成分及分压强。     

Structural study of very thin anodic alumina films on silicon by anodization in citric acid aqueous solution

The formation of thin alumina films on a silicon substrate by anodization in a mild acid, specifically in 1% wt citric acid aqueous solution, is investigated by transmission electron microscopy (TEM). We present a comparative study between two cases of starting material: pure aluminum and an alloy of aluminum with 1% silicon. In both cases the thickness of the Al layer was less than 50 nm. It was observed that under exactly the same conditions, in the first case the anodization was stopping before anodizing the whole film and a remaining non-anodized Al layer was always present, while in the second case, the Al layer was fully anodized, resulting in an alumina matrix with a very high density of silicon nanocrystals of uniform sizes embedded in it. In both cases the alumina film was compact and amorphous.     

Polarization curves of Fe-28% Cr-24% Co-1% Si permanent magnet alloy in sulphuric acid solution

The potentiokinetic curves of anodic polarization of magnetically hard Fe-28% Cr-24% Co-1% Si alloy in sulphuric acid of pH 0 were plotted. The Fe-Cr-Co-Si alloy has been subjected to four different treatments that are usually used for generation of magnetic properties. Research has shown that the heat treatment at temperatures of the order of 640 °C applied for generation of two-phase structure causes the drastic decrease of corrosion resistance of the tested alloy.     

先进制造技术在我国制造业应用的探讨

通过分析先进制造技术的基本特征，从技术和应用环境两个方面探讨了影响先进制造技术实施的主要因素；在此基础上提出了适合我国制造业实施先进制造技术的基本步骤和策略。     

表面活性剂对液膜法提取柠檬酸影响的研究

表面活性剂种类和浓度对液膜法提取柠檬酸的提取率和乳液溶胀都有一定影响 .在给定条件下 ,提取率随表面活性剂浓度的增大而提高 ,由LMA -1所制成的液膜对柠檬酸的提取率比Span -80高 ,且产生的乳液溶胀也比较小     

Corrosion behavior of Al, Sc-co-doped ZnO thin films in 3.5% NaCl solution

The corrosion behavior of Al, Sc-co-doped zinc oxide films (with Sc-dopant varying in 0, 0.01, 0.13, 0.24 and 1.07 wt.% Sc) in 3.5% NaCl solution has been investigated. It was compared to that of the commercial indium tin oxide (ITO) thin film. The films were prepared by sputtering on the ZnO (4 N) target with RF and on the targets of Al (4 N), Al-0.4 wt.% Sc, Al-0.8 wt.% Sc, Al-1.7 wt.% Sc alloy and pure Sc with DC. The electrochemical studies revealed that the corrosion resistance of the films increases in the order AZO < Sc-doped AZO < ITO < annealed AZO (at 300 °C for 1 h). The AZO doped with higher Sc-content is more resistant to corrosion. Examining the surface morphology through atomic force microscope (AFM) and scanning electron microscope (SEM), the film, which is more susceptible to corrosion depicted a rougher surface. The electrical resistivity of the films maintained almost unchanged in 120-h test. However, the optical transmittance varied with the concentration of Sc-dopant in the films. The higher Sc-dopant in the film the more stable it is to maintain higher transmittance. Higher corrosion resistance for the Sc-doped AZO in comparison with the monotonic AZO is attributed to a release of lattice strain by the Sc (III)-dopant which its size is similar to Zn (II). The most corrosion-resistant specimen (i.e., Sc-doped AZO annealed at 300 °C for 1 h) is considered to have the complete release of the lattice strain.     

Aggregation behavior of Na-neutralized styrene-ran-methacrylic acid copolymers in aqueous solution

The aggregation behavior of un-neutralized, partly and fully Na-neutralized poly(styrene-ran-methacrylic acid) copolymers in aqueous solution was investigated using a SEM technique. It was observed that the un-neutralized copolymer formed spherical particles on the Si wafer, and the average size of particles was ca. 160 nm. The particle sizes did not change much with acid content. Upon the neutralization of the acid groups of the copolymer with NaOH, the copolymer became more hydrophilic, leading to the formation of network-like feature consisting of much smaller particles (< 50 nm), compared to those of the acid copolymers. With increasing ionization, the boundary of the particles forming networks faded away, implying the formation of tubular structures.     

Effect of tannic acid on corrosion behavior of carbon steel in NaCl solution

Corrosion behavior of unrusted Q235 carbon steel was investigated in 3.5% NaCl solutions with 1–5 wt%tannic acid addition, using electrochemical methods including electrochemical impedance spectra(EIS),potentiodynamic polarization and scanning vibrating electrode technique(SVET) combined with surface analysis. Results show that the corrosion rate decreases with increasing tannic acid concentration. As compared with tannic acid-free solution, 1% tannic acid does not provide inhibition effect during the whole immersion, while inhibition effect is observed for 3% tannic acid after 8 h and for 5% tannic acid after 4 h. The inhibition efficiency by weight loss measurements(áw) for 1%, 3%, and 5% tannic is around-17.2%, 40.3%, and 51.5%, respectively. Corrosion of unrusted carbon steel in the presence of tannic acid is attributed to the joint effect of tannic acid adsorption and pH decrease. Formation of ferric-tannates is verified by X-ray photoelectron spectroscopy(XPS) and Raman spectra. The reaction mechanism between tannic acid and unrusted carbon steel is proposed.     

壳聚糖在柠檬酸溶液中溶解行为研究

采用电位测试法和电导测试法研究壳聚糖在柠檬酸溶液中的溶解行为.即利用电位测试法确定壳聚糖质子化度,利用电导测试法确定壳聚糖溶解于柠檬酸中质子化的作用.结果表明:壳聚糖质子化度α=1.0时,完全溶解;柠檬酸浓度、溶解温度和溶解时间都会影响壳聚糖的溶解,酸浓度的增大、溶解温度的升高和溶解时间的延长都有利于壳聚糖的溶解.壳聚...     

Investigation of the corrosion behavior of aluminum bronze alloy in alkaline environment

In this study, the effect of amino-based additives including ammonia, ethanolamine and a mixture of two additives on the pH change of condenser water and corrosion behavior of aluminum bronze alloy as a structural material of condenser were investigated. The results of polarization curves, wheel tests and inductively coupled plasma showed that by increasing the pH from 8.5 to 10.5, the corrosion rate of aluminum bronze alloy and the dissolution rate of alloying elements are increased. The effect of amino-based additives at the same pH is similar to each other. A comparison of corrosion rates determined by polarization curves. The corrosion rates for solutions contained ammonia and ethanolamine additives at pH = 10.5, were 2.92 ⋅ 10⁻² and 4.55 ⋅ 10⁻² mm/y respectively. The wheel test results indicated that the corrosion rates of solutions containing different additives increased to 1.1028 mm/y and 0.4504 mm/y for solutions containing ammonia and ethanolamine, respectively. Therefore, due to similar environmental conditions in the condenser and the wheel test because of the presence perturbation and biphasic fluid, it can be concluded that at pH above 10, aluminum bronze alloy has lower corrosion rate in the cooling water containing ethanolamine than ammonia additives.     

Sliding friction and wear behavior of Fe-based bulk metallic glass in 3.5% NaCl solution

The corrosion wear behaviors of a Fe-based bulk metallic glass Fe_66.7C_7.0Si_3.3B_5.5P_8.7Cr_2.3Al_2.0Mo_4.5 against Si₃N₄ ceramic ball was studied in a 3.5% NaCl solution and using a unidirectional tribometer with the ball-on-disk configuration. During friction process, the Fe-based BMG showed tribochemical reaction with the 3.5% NaCl solution. Wear occurred mainly through an abrasive wear mechanism and corrosive wear effects. The overall average friction coefficient was in the range of 0.18 to 0.25 according to the test conditions and slightly decreased with increasing load. The wear resistance of the BMG was better than that of the conventional bearing steel, demonstrating the potential of the BMG as a viable engineering alloy for anti-corrosive wear applications.     

柠檬酸包覆合成LiFePO4/C工艺的优化

以柠檬酸为碳源,采用机械液相球磨与高温固相烧结相结合制备了LiFePO4/C复合材料,考察了烧结温度、烧结时间、柠檬酸用量、球磨时间等工艺条件对LiFePO4/C材料性能的影响.采用XRD、SEM和恒电流充放电等手段对该材料进行结构表征和电化学性能测试.结果表明,合成LiFePO4/C复合正极材料的适宜工艺为,球磨时间10h,烧结温度600℃,烧结时间18h,柠檬酸用量10%,气体流量0.6L/min.在优化工艺条件下制备的LiFePO4/C复合正极材料首次放电容量可达到146.2mAh/g.     

Corrosion fatigue behavior of extruded magnesium alloy AZ80-T5 in a 5% NaCl environment

The corrosion fatigue behavior of extruded AZ80-T5 magnesium alloy has been investigated in three different environments: (1) a low humidity environment (35-40% relative humidity), (2) a high-humidity environment (80% relative humidity), and (3) a 5 wt.% NaCl environment. Fatigue tests were conducted under axial loading at a stress ratio of −1 and at a frequency of 20 Hz. It was found that in both the high-humidity environment and in the 5 wt.% NaCl environment the fatigue strength was reduced relative to the low humidity environment, especially in the NaCl environment: the reduction rates of fatigue limit under high humidity and NaCl environments were 18%, and 78%, respectively. The reduction of fatigue strength under the corrosive environments was attributed to the pit formation and growth. At low stress amplitudes, multiple pits were formed and coalesced to form a large pit under NaCl environment. A fatigue crack nucleated when the pit grew to the critical size.     

Agglomeration behavior of chromia nanoparticles prepared by amorphous complex method using chelating effect of citric acid

Chromia (Cr₂O₃, chromic oxide, Eskolaite) nanoparticles were prepared by amorphous complex method using citric acid as a chelating agent. As a precursor for chromic oxide particle, dried gel with a three-dimensional network consisted of the molar ratio of [citrates]/[chromium ions]=2:1 was prepared. Finally, chromic oxide nanoparticles were formed by calcination of precursor gel at 700 °C for 2 h. Obtained chromic oxide particles were characterized by thermogravimetric and differential thermal analysis, X-ray diffraction, field emission scanning electron microscopy, and Brunauer–Emmett–Teller surface area measurement. It turned out that chromic oxide nanoparticles showed highly agglomerated structure consisted of weakly attached primary particles with each other by van der Waals and capillary adhesive forces. The size distribution of the individual particles was about 20–50 nm. Estimated average particle size from BET surface area was 29.21 nm. The reason for the formation of highly agglomerated structure was discussed.