腰果壳油的蒸馏及馏分成分研究

用蒸馏法从商品腰果壳油中提取主成分腰果酚,采用红外光谱、质谱-计算机联用仪对蒸馏馏分进行定性分析。结果表明,常压或减压蒸馏均能得到腰果壳油的主成分,减压蒸馏可大大提高馏分的得率。在真空度0~500 Pa下进行减压蒸馏时,能得到最高得率为77.58%的淡黄色油状馏分,馏分为腰果酚和其它酚类化合物,主馏分腰果酚中带有饱和、单烯、双烯和三烯的长侧碳链。     

回用水对冷却水系统316L不锈钢的腐蚀

城市污水回用作循环冷却水系统,讨论了NH3-N、COD、Cl-、SO42-等因素对316L不锈钢耐腐蚀性的影响。极化曲线表明:当NH3-N的质量浓度超过18 mg/L时,NH3-N促进了不锈钢的点蚀;COD对316L不锈钢的点蚀并无多大的影响;Cl-促进点蚀,而SO42-的质量浓度小于300 mg/L时,SO42-对其点蚀有缓蚀作用。     

液相沉积法在304不锈钢上制备纳米二氧化钛涂层

采用液相沉积法在304不锈钢上制得外观均匀致密的纳米TiO2涂层,热处理后为锐钛矿晶型。这种纳米TiO2涂层的颜色和厚度随(NH4)2TiF6与H3BO3浓度比和沉积时间的变化而不同,其光电化学效应与防腐蚀性能都比溶胶–凝胶法所制备的TiO2薄膜差。     

The corrosion resistance of 316L stainless steel coated with a silane hybrid nanocomposite coating

The present work aims at evaluating the corrosion resistance of 316L stainless steel pre-treated with an organic–inorganic silane hybrid coating. The latter was prepared via a sol–gel process using 3-glycidoxypropyl-trimethoxysilane as a precursor and bisphenol A as a cross-linking agent. The corrosion resistance of the pre-treated substrates was evaluated by neutral salt spray tests, linear sweep voltammetry and electrochemical impedance spectroscopy techniques during immersion in a 3.5% NaCl solution. In addition, the effect of the drying method as an effective parameter on the microscopic features of the hybrid coatings was studied using Fourier transform infrared spectroscopy and scanning electron microscopy. Results show that the silane hybrid coatings provide a good coverage and an additional corrosion protection of the 316L substrate.     

Corrosion protection of new composite polymer coating for carbon steel in sulfuric acid medium by electrochemical methods

In this paper, electropolymerization technique has been used for the obtained of new composite: polypyrrole – dioctyl sulfosuccinate sodium/poly N-ethylaniline (PPY-AOT/PNEA) coatings over carbon steel of type OLC 45 electrode for anticorrosion protection. The PPY-AOT/PNEA coatings were successfully synthesized onto OLC 45 electrode by galvanostatic deposition from aqueous solutions 0.1 M NEA, 0.1 M PY, 0.01 M AOT and 0.3 M H₂C₂O₄ solution at different current densities (5, 3 and 1 mA/cm²) in different molar ratio. The anionic surfactant (AOT) as a dopant ion used during electropolymerization can have a significant result on the anticorrosion protection of the composite film by hindering the penetration of aggressive ions. The polymeric composite coatings have been analyzed by cyclic voltammetry (CV), Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) methods. The corrosion resistance of PPY-AOT/PNEA coated carbon steel has been examined by potentiodynamic polarization techniques and electrochemical impedance spectroscopy (EIS) methods in 0.5 M H₂SO₄ solutions. The data of the corrosion samples demonstrated that PPY-AOT/PNEA coatings assure a great anticorrosion protection of OLC 45 electrode in corrosive media. The corrosion rate of PPY-AOT/PNEA coated OLC 45 has been indicated to be ~9 times lower than of uncoated electrode. The corrosion protection effectiveness of the composite coating is more than 89%. The best efficiency is accomplished of PPY-AOT/PNEA obtained by electrodeposition at 5 mA/cm² current densities applied in molar ratio 5:1.     

液氯计量槽的腐蚀与防护

文中以液氯计量槽被腐蚀破坏为例,阐述了常见几种腐蚀的形态和行为。认为液氯计量槽主要存在点腐蚀、疲劳腐蚀、冲刷腐蚀３种形态,同时提出了改进建议。     

不锈钢管材蒸汽发生器的腐蚀与防护

介绍了蒸汽发生器不锈钢管材及其腐蚀形式,美国西屋公司希平港1号核电厂蒸汽发生器、我国某核动力装置立式蒸汽发生器和卧式蒸汽发生器的腐蚀,对不锈钢管材蒸汽发生器的多项防护措施.     

316L不锈钢凝汽管在运河水质循环水中的应用

简述了运河徐州段的水质状况和316L不锈钢凝汽器管的物化性能,给出了一种以PBTCA、POCA、PESA、PAPEMP和T-225为主要成分的复合阻垢剂,用极限碳酸盐硬度法和动态模拟法试验,结果表明:在按补水计投药质量浓度为10 mg/L时系统可在k=3.5±0.5的浓缩倍数下安全运行;运河水对碳钢、HSn70-1B铜合金及316L不锈钢均具有较强的腐蚀作用,阻垢剂的加入将加剧金属的腐蚀;在系统中投加一定浓度的BTA-TTA-有机胺混合物可保证316L不锈钢的腐蚀率＜0.003 mm/a.     

水性腰果壳液固化剂的试制与应用

采用农林副产品腰果壳液,通过一系列的化学反应,合成了水性腰果壳液固化剂,讨论了乳化剂的用量、种类对其性能影响,乳液与固化剂的配比对漆膜光泽的讨论以及将水性腰果壳液固化剂配制的水性环氧带锈防锈漆与溶剂型涂料的比较。     

氯化液干燥器腐蚀分析和防护

分析了氯化苯氯化液干燥器的腐蚀原因、腐蚀状态及防范措施。     

磷钼酸在酯化反应体系中对316不锈钢的腐蚀抑制机理

采用扫描电子显微镜(SEM)和X射线光电子能谱(XPS)研究了模拟醋酸丁酯反应(CH3COOH、H2SO4、H3PMo12O40,105℃)条件下316不锈钢(316SS)的表面形貌和元素组成。结果表明,磷钼酸经物理吸附在不锈钢表面形成保护层,并发生氧化还原反应,生成的水合物、氧化物、难溶盐类沉积在不锈钢表面,形成致密的钝化膜,从而抑制316SS的局部腐蚀,阻止点蚀的扩散和蔓延,PMo12O430-、MoO42-和CrO42-使钝化膜表层具有阳离子选择性,能阻挡SO24-通过该膜到达金属表面,膜内层结晶态氧化物具有阴离子选择性,阻止基体金属离子穿过钝化膜而溶解,从而抑制局部腐蚀的进一步扩展。     

Corrosion protection of epoxy‐coated steel using different silane coupling agents

To suppress steel corrosion at elevated temperature and in humid condition, silane coupling agents N‐β‐aminoethyl aminopropyltrimethoxysilane (AAPS), γ‐glycidoxypropyltrimethoxysilane (GPS), and bis[3‐(trimethoxysilyl)‐1‐phenylpropyl]tetrasulfide (RC‐2) were introduced as primers into an epoxy/steel system. Silane coupling agents and epoxy were coated onto the steel surface using the solution casting method. The polymer degradation and steel corrosion formation after heat and humid treatment were investigated by Fourier transform infrared reflection and absorption spectroscopy (FTIR–RAS) and scanning electron microscopy (SEM). Compared to various silane treated epoxy/steel systems, the AAPS‐treated epoxy/steel (AAPS/epoxy = 6 : 4) system suppressed steel corrosion at 400°C for 10 min in air and for 5 days at 60°C in 100% relative humidity. This is due to the formation of Si O Si linkage and Fe O Si bond on steel surface, which are resistant to water diffusion and thermally stable at elevated temperature. The relationship between chemical bonding at the steel–epoxy interface and corrosion protection on the steel surface was also investigated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 585–593, 1999     

Electrochemical investigations of pitting corrosion behaviour of type UNS S31603 stainless steel in thiosulfate-chloride environment

The pitting corrosion behaviour of type UNS S31603 stainless steel (316L SS) in 0.01, 0.05 and 0.1 M thiosulfate ion (S₂O₃ ^2–) in the absence and presence of various concentrations of chloride ion (Cl^–) was studied using the cyclic potentiodynamic polarization method. The influence of major factors which affect pitting corrosion such as pH and temperature, were also investigated. It was found that both the pitting potential (E _pit) and the repassivation potential (E _rp) decreased with increase in Cl^– concentration and solution temperature and a more pronounced difference in E _pit values for various concentrations of S₂O₃ ^2– in 1.0 M Cl^– was obtained at lower temperatures. The effect of pH on E _pit, E _corr and E _rp values for different concentrations of S₂O₃ ^2– in the presence of 1.0 M Cl^– was also determined.     

Corrosion protection of mild steel by polypyrrole phosphate composite coating

Electrodeposition of polypyrrole phosphate (PPy–P) on mild steel (ST₁₂) was achieved in oxalic acid medium using cyclic voltammetry (CV) technique. Adherent and homogeneous PPy–P films were obtained. The corrosion behavior of mild steel with phosphate (PPy–P) coatings in 3.5% NaCl solutions was investigated through potentiodynamic polarization technique, open circuit potential–time curves, and electrochemical impedance spectroscopy (EIS). Based on a physical model for the corrosion of mild steel composite, the Zview (II) software was applied to the EIS to estimate the parameters of the proposed equivalent circuit. It was found that the PPy–P coatings could provide much better protection than PPy. The effect of phosphate on the morphology and structure of the passive film was investigated by scanning electron microscopy and electron dispersion X-ray analysis (EDX). The results reveal that the PPy–P coated electrode provided a noticeable enhancement of protection against corrosion process.     

液氯汽化器的腐蚀与防护

分析了液氯汽化器列管腐蚀穿孔的原因:设备加工制造存在缺陷;蒸汽加热方式使水质变差,水的腐蚀性增强;水中溶解氧导致电化学腐蚀;间断式生产导致沉积物处腐蚀。提出了防腐措施:严把设备制作质量关;向水中添加缓蚀阻垢剂;向水中加入三聚磷酸钠,提高水的pH值。采取防腐蚀措施后,延长了设备使用寿命。     

Formation and composition of nanoporous films on 316L stainless steel by pulsed polarization

Nanoporous films have been formed on 316L stainless steel in 5 mol dm⁻³ sulphuric acid at 60 °C by square wave pulse polarization between active or transpassive and passive potentials, and characterized using glow discharge optical emission spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, Rutherford backscattering spectroscopy and nuclear reaction analysis. The films are shown to be chromium- and molybdenum-rich relative to the substrate, and to consist mainly of sulphates, oxides and hydroxides. The morphology and composition of the films are discussed in relation to the polarization conditions and mechanism of film formation.     

Preparation and evaluation of a new anti-corrosive coating based on asphalt cement blended with polyesteramide resin for steel protection

Asphalt cement is a material commonly used in coating applications due to its good adhesion properties and relatively low cost. Unfortunately it has the drawback of being slow to dry. Long polyesteramide resin (PEA) is predominantly used for air-dry and force-dry industrial coatings onto metal surfaces, yet is considered to be a relatively weak material. This paper focuses on the potential synergy of mixing asphalt cement, of penetration grade 60/70, with polyesteramide resin to produce industrial coatings for steel applications, with the aim of overcoming the slow drying time of the asphalt cement and the relative weakness of PEA resin. To achieve this aim, PEA resin was mixed with asphalt cement in a range of concentrations from 3 to 12% (w/w). The prepared coating blends were characterised physically using scanning electron microscopy (SEM), while the performance of the coatings were evaluated for mechanical properties and corrosion resistance in selective chemical reagents, following complete immersion for the duration of 84 days. The results obtained concluded that generally, a blend of asphalt cement and polyesteramide resin produces an effective material for industrial coating applications. Also, 9% and 12% PEA resin content produced high-quality anti-corrosive material as compared to virgin asphalt cement. The degree of modification depends upon the properties of the asphalt and the content level of the polyesteramide.     

Protection of stainless steel by polyaniline films against corrosion in aqueous environments

Polyaniline (PANI) thin films were electrochemically deposited by cyclic voltammetry on stainless steel electrode previously covered by a thin film of polyvinyl acetate (PVAc). The corrosion resistance of PANI covered stainless steel substrates was estimated by using potentiodynamic polarization curves and its linear polarization resistance (LPR) was measured in 0.5 M H₂SO₄, 0.5 M NaCl and 0.5 M NaOH aqueous solutions at room temperature. The results indicate that the PANI-PVAc films did improve the corrosion resistance of the stainless steel in NaOH, behaving even worst, in the case of PANI film, than the uncoated substrate. In H₂SO₄ both PANI and PANI-PVAc coatings gave good protection for the stainless steel electrode, with a slightly better performance of PANI-PVAc than PANI. In NaCl solution both PANI and PANI-PVAc films provided a good protection against corrosion. The better performance of PANI-PVAc coatings for corrosion protection in basic media may be due to its major chemical stability compared to simple PANI films, which lose their conductivity in high pH solutions. The E _corr (free corrosion potential) value of the coated substrate was in the passive region of the uncoated substrate in acidic environment but in the active region in neutral or basic environment.     

Corrosion behavior of polypyrrole coating doped by dodecylbenzenesulfonate for mild steel in acidic media

This paper describes the electrochemical synthesis of a dodecylbenzenesulfonate doped polypyrrole (PPy-DBS) coating on a passivated mild steel (MS) and investigation of its corrosion protection behaviors. This coating was prepared by cyclic voltammetry technique and characterized by Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FESEM). The corrosion protection features of the PPy-DBS coated MS were studied in different acid media (0.5?mol L^?1 H₂SO₄ and 0.5?mol L^?1 HCl solutions) using linear potentiodynamic polarization, electrochemical frequency modulation and, electrochemical impedance spectroscopy methods. Electrochemical measurements and FESEM images reveal that the PPy-DBS coating presents effective protection for the MS against corrosive species. This may be ascribed to the barrier effect of the polymer coating and utilization of the dodecylbenzenesulfonate dopant with large size during the electropolymerization process.     

Corrosion of similar and dissimilar metal crevices in the engineered barrier system of a potential nuclear waste repository

Crevice corrosion is considered possible if the corrosion potential (E_corr) exceeds the repassivation potential for crevice corrosion (E_rcrev). In this study, potentiodynamic polarization and potentiostatic hold were used to determine the E_rcrev of similar and dissimilar metal crevices in the engineered barrier system of the potential Yucca Mountain repository in 0.5 M NaCl, 4 M NaCl, and 4 M MgCl₂ solutions at 95 °C. The results were compared with data previously obtained using crevices formed between Alloy 22 and polytetrafluoroethylene. It was observed that, except for Type 316L stainless steel, all other metal-to-metal crevices were less susceptible to crevice corrosion than the corresponding metal-to-polytetrafluoroethylene crevices. Measurements of galvanic coupling were used to evaluate the crevice corrosion propagation behavior in 5 M NaCl solution at 95 °C. The crevice specimens were coupled to either an Alloy 22 or a Titanium Grade 7 plate using metal or polytetrafluoroethylene crevice washers. Crevice corrosion of Type 316L stainless steel propagated without repassivation. For all the tests using a polytetrafluoroethylene crevice washer, crevice corrosion of Alloy 22 was initiated at open circuit potential by the addition of CuCl₂ as an oxidant, whereas no crevice corrosion of Alloy 22 was initiated for all the tests using Alloy 22 or Titanium Grade 7 metals as crevice washer. However, crevice corrosion propagation was found to be very limited under such test conditions.