表面处理对锌黄/醇酸涂层体系在碱性清洗剂中防护性能的影响

采用浸泡试验和电化学阻抗技术(EIS)研究经不同表面处理的7000系铝合金/涂层试样在碱性清洗剂中的耐蚀行为,得到表面处理对涂层防护性能的作用规律。结果表明:钝化、喷砂、喷砂/钝化和蚀刻涂装等4种表面处理方式都能提高锌黄底漆底层/醇酸磁漆面层这一涂层体系在碱性清洗剂中的防护性能,其作用能力从小到大依次为:钝化处理、喷砂处理、蚀刻涂装处理、喷砂/钝化处理。     

锂电池EIS测试参数拟合中频率范围的影响分析

锂电池EIS等效电路参数对锂电池的研究有非常重要的价值,为准确拟合出等效电路参数,不同频率下的阻抗可反映不同的电化学过程,因此电路参数准确性也不一样,文章取低频下限值为0.01Hz,对高频部分的选取进行拟合实验对比,通过对22组不同频率上限的数据进行拟合分析,表明在某一的频率范围内进行等效电路参数拟合能获得最佳的拟合效果。     

有机涂层防腐性能评价技术的研究进展

对有机涂层防腐性能评价技术进行了综述：常规方法通过试样表面变化进行评价,无法揭示金属腐蚀动力学规律及深层防护机理;电化学方法快速简便,信息量相对丰富,可对涂层防护性能进行定量与半定量评价,但部分检测仪器较昂贵;光谱学方法灵敏度高,有利于提示腐蚀机理,观察腐蚀过程中的微观信息,但图谱解析有时较为困难.     

聚酯型涂料在鸡精调味料马口铁罐包装上的应用

分别以环氧酚醛型涂料和聚酯型涂料作为马口铁罐涂层材料,以鸡精调味料(以下简称鸡精)作为包装内容物,系统对比研究2种涂层的马口铁罐的封罐效果、耐腐蚀性以及对鸡精货架期内的品质影响等方面的差异性.结果表明,聚酯型涂层的马口铁罐与环氧酚醛型涂层的马口铁罐比较,包装罐的封罐效果、耐腐蚀性以及对鸡精货架期内的品质影响等方面均无显...     

阻抗微生物检测过程中的等效电路模型及各阻抗参数变化

应用等效电路的研究方法分析了利用双电极进行阻抗微生物检测时,测试管内的等效电路.通过分析Bode图,得到测试管内的总阻抗包含不随频率变化的电导、随频率呈指数变化的电导、随频率呈指数变化的阻抗虚部3项.结合检测过程中的Nyquist图,得到测试管的等效电路为常相住角元件(CPE)与电阻R的串联.用matlab进行参数估计...     

有关罐头食品腐蚀的电化学

罐头食品主要是把食品密封在马口铁制容器中,马口铁即低碳钢薄板镀锡的铁皮。但镀锡层并不是完整无缺的,总是有微细小孔存在。在周围介质的作用下,罐内、外壁都可能发生腐蚀,尤其是电化学腐蚀,即铁锡形成...     

陶瓷强化涂层在饮料灌装机中的应用

为有效提升饮料灌装机内壁的耐磨性和耐腐蚀性，基于等离子喷涂技术制备一种陶瓷涂层。在不同工作电流、喷涂距离和喷涂速度条件下，测试并分析电弧压力、涂层粗糙度和孔隙率等特性的变化规律。制备不同层厚的涂层试样，对其微观形貌、显微硬度和磨损率进行对比分析，得出喷涂热源对多层涂层力学性能的影响机理。将涂层试样分别置于弱酸（醋酸溶液）、弱碱（苏打水溶液）和80℃恒温环境下进行腐蚀处理，研究涂层磨损形貌及原理。研究表明，陶瓷涂层可将母材表面硬度提升43.4%，磨损率降低22.6%，腐蚀前后的粗糙度偏差低于5%，显著改善力学性能和耐腐蚀性能，对弱酸、弱碱和变温环境适应能力强。研究为食品机械表面强化技术的发展提供借鉴。     

直升机用铝合金有机涂层抗腐蚀性能研究

为研究直升机用铝合金有机涂层在海洋环境下的抗腐蚀性能,采用两种新型铝合金有机涂层(A,B涂层)和陆基直升机用铝合金涂层(C涂层)分别对设计的典型结构模拟件及铝合金陪试件进行喷涂,并进行10个周期的加速腐蚀试验。试验前后涂层的形貌、失光率和电化学阻抗的测试结果表明,试验后三种涂层外观基本完整,A涂层失光率维持在5%以内,无剥落现象,C涂层失光率下降较大,并有剥落现象,B涂层介于两者中间;A涂层的阻抗在107Ω·cm2以上,B,C涂层的阻抗下降至106-107Ω·cm2。A涂层抗腐蚀性能更优异,更加适用于海洋环境。     

酸性环境下金属三片罐涂层中三聚氰胺迁移规律

研究金属三片罐内涂层中三聚氰胺迁移进入酸性饮料中的迁移规律,并以模拟物为体系建立迁移数学模型,进行效果验证。结果表明:温度越高,迁移进入酸性饮料中的三聚氰胺的速度越快,迁移达到平衡所需时间越短,但迁移值远低于欧盟的限量标准30mg/kg。所建的模型能够较好地预测金属三片罐中三聚氰胺的迁移行为,为评估三片罐在食品包装中的安全性提供试验依据。     

卤氧化铋/纸浆纤维复合光催化纸的原位制备及甲醛去除效果研究

将卤氧化铋(BiOX,X=Cl、Br、I)原位沉积至纸浆纤维(PFs)上,制得BiOX/PFs复合光催化纸,并对其甲醛去除性能进行了评价。研究发现,在相同BiOX沉积率下,BiOI/PFs复合光催化纸的甲醛去除性能最佳,甲醛去除率为75%。与BiOCl/PFs复合光催化纸相比,BiOBr/PFs和BiOI/PFs复合光催化纸具有更优异的可见光催化性能,甲醛去除率分别为61%、74%和75%。采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、X-射线光电子能谱仪(XPS)及电化学阻抗谱(EIS)等对BiOX/PFs复合光催化纸进行了表征,证明BiOX成功与PFs复合,最后对BiOX/PFs复合光催化纸的可见光降解甲醛机理进行了分析。     

Detection of corrosion-induced metal release from tinplate cans using a novel electrochemical sensor and inductively coupled plasma mass spectrometer

Corrosion-induced tin and iron release were investigated by inductively coupled plasma mass spectrometer (ICP-MS) and a novel electrochemical sensor. The sensor was used for detecting the corrosion extent of energy drink cans by techniques of electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN), and a metal release mechanism was proposed. ICP-MS results showed that tin and iron release increased with the storage time while EIS and EN results showed that coating resistance, charge transfer resistance and noise resistance decreased with the storage time, which indicated that the corrosion beneath the organic coating induced metal release. Consequently, a clear and direct relationship was obtained between the ICP-MS and the electrochemical results. Furthermore, the internal surface morphology of the cans was characterized by scanning probe microscopy (SPM). It was concluded that the novel electrochemical sensor that allowed in situ measurement could be used for the evaluation of corrosion extent and metal release in beverage cans in a more economical and rapid way.     

The effect of sulphur-containing fungicides on the corrosion of plain cans of fruit

The addition of 2–5 ppm of TMTDS (tetramethylthiuramdisulphide) or ziram markedly decreased the shelf life of canned pears, but 1 ppm of these materials had little effect. The addition of trace levels of sulphur or captan to canned pears appeared to increase the shelf life; addition of sodium sulphide appeared to have a negligible effect on shelf life. The shelf life of canned peaches, apricots, pineapple, apples, and citrate solution was also decreased by the addition of 5 ppm TMTDS or ziram. TMTDS and ziram caused pitting of the base steel of the tinplate with little attack on the tin coating. Pitting was not seen in cans containing added sulphur, sulphide, or captan and the rate of corrosion of the tin coating was less than in cans containing no added chemicals. Formation of passive films and reduction of the hydrogen overpotential were considered to be important factors influencing corrosion of cans containing the added agricultural chemicals.     

A New Approach for the Determination of Fish Freshness by Electrochemical Impedance Spectroscopy

Changes in several dielectric parameters of carp, herring and sea bass during their storage after death at 4 °C, 15 °C and 25 °C were examined by electrochemical impedance spectroscopy (EIS) in the frequency range of 0.1 Hz to 100 kHz. This method offers a simple, rapid and in situ measurement of the onset of spoilage. The phase angle and admittance changes are the best freshness indicators, from which four classifications of freshness may be defined for all of the tested fish species. Warburg‐type impedance and CE (chemical reaction preceding an electrochemical reaction) processes were observed in the relaxation process during storage and a proposed equivalent circuit satisfactorily described the overall electrochemical behavior.     

Corrosion inhibition with different protective layers in tinplate cans for food preservation

BACKGROUND: In this work the influence of essential onion oil (EOO) on the protection of tinplates was compared with dioctyl sebacate oil (DOS) and epoxy phenolic lacquers, which are frequently used in the food canning industry. RESULTS: When EOO as the protective layer instead of DOS oil was used, tinplate porosity, measured electrochemically (7.58 ± 1.97 µA cm^?2 and 23.0 ± 1.3 µA cm^?2, respectively), and iron coating mass, calculated from AAS data (1.52 ± 0.15 mg m^?2 and 3.14 ± 0.42, respectively), was much lower indicating better corrosion protection. At higher storing temperature (36 °C) the addition of EOO to canned tomato purée enhanced the formation of hydrogen with time. The increasing volume fraction of H₂ (from 34.0 to 90.9% for cans without nitrates, and from 33.8 to 89.2% for cans with nitrates) is an indicator that corrosion takes place. CONCLUSION: As the use of EOO improves the protection of tinplate compared with DOS oil, and is almost as effective as epoxy phenolic lacquer, the addition of EOO can be recommended due to lower cost of canned food production and enhanced organoleptic properties, but the storage temperature has to be lower then 36 °C. Copyright © 2010 Society of Chemical Industry     

External corrosion of cans during thermal treatment

Factors affecting external corrosion of food cans, in contact with various metals in aqueous medium, during thermal processing were investigated. Simple electrochemical measurements of potentials and couple currents were found to be suitable for evaluation of the tendency and extent of corrosion. A stainless steel bath was found to cause external corrosion of tin cans. Several inhibitors were investigated as to their efficiency in minimizing this phenomenon. Two commercial inhibitors were found to have a limited effect, whereas sodium nitrite proved to be effective at a level of 300 p.p.m. It became apparent that increasing the anodic area (tinplate) in relation to cathodic area (stainless steel), i.e. loading equipment to capacity, was beneficial in reducing corrosion in this system. An aluminium electrode afforded protection to tin cans in a stainless steel bath at 85°C.     

Electrical impedance spectroscopic study of mandarin orange during ripening

Electrical impedance spectroscopy (EIS) as non-destructive investigation has been conducted to study the electrical impedance variations during ripening of mandarin orange. The objective of the work is to study the electrical impedance variations and variations in weight of the orange fruit with different ripening state. Electrical equivalent circuit has been modeled relative to the Nyquist plot obtained during the ripening of orange by non-linear curve fitting technique. EIS studies on orange fruit have been conducted by applying a small amount of alternating current through an array of Ag/AgCl electrodes attached to the orange fruit. The impedance and phase angles of orange fruit are measured at frequency sweep from 50 Hz to 1 MHz for 100 frequency points. The results revealed that the impedance, real part and imaginary part of the impedance all are increased and the weight of orange are decreased with the increase in ripening state. It is observed that the electrical equivalent circuit of orange fruit contains a constant phase element.     

桃果实电特性的频率变化

以‘秦光2号’油桃为测试对象,研究果实电参数的频率特性。测定不同频率下桃果实14个电参数值,用SPSS软件分析并拟合果实的随频率变化的函数方程(相关性都达显著水平)。结果表明：除了品质因子(Q)随频率变化无规律,其余13个电参数都随频率呈有规律的变化(是电激励频率的函数),其中复阻抗(Z)、串联等效电阻(Rs)、并联等效电阻(Rp)、电抗(X)随电激励频率变化呈三次函数下降变化;串联等效电容(Cs)、并联等效电容(Cp)随频率变化规律相似,阻抗相角(θ)随频率呈U型变化,损耗系数(D)随频率呈W型变化;导纳(Y)、电纳(B)、串联等效电感(Ls)、并联等效电感(Lp)、电导(G),随电激励频率呈指数上升变化。     

牛宰后肌肉生物电阻抗值变化及其影响因素的研究

本试验用四电极法在多频(5-200KHz)条件下对宰后牛骨骼肌肉的电阻抗特性进行了初步的研究。发现牛骨骼肌生物电阻抗与肌肉纤维方向,电流信号频率和宰后肌肉所经历的阶段有关。横向电阻(沿垂直于骨骼肌纤维方向)大于纵向电阻(沿骨骼肌纤维方向),而且受电流信号频率的影响较明显,尤其是在5KHz～100KHz范围内。牛宰后生物电阻抗的变化与pH值的变化有一定的相关性。     

Effect of sterilisation and storage conditions on the migration of bisphenol A from tinplate cans of the Lebanese market

The use of bisphenol A (BPA) in lacquer coating of food cans has been restricted by different authorities in many countries, such as in Europe. However, such regulation does not exist in many other countries including Lebanon. Due to the lack of data on the quality of Lebanese can production; this study investigates the migration of BPA from two types of tinplate cans manufactured in Lebanon, before and after sterilisation. Cans were analysed under different storage conditions (time and temperature) and filled with an aqueous simulant. The determination of BPA was carried out using UPLC with fluorescence detection, and further confirmed by MS detection. After sterilisation BPA levels drastically increased from an average of 0.15 to 109 µg/kg, giving a BPA migration around 10.5 µg/dm² for both types of cans. Storage temperature and time had no significant influence on BPA levels in sterilised cans (p-value > 0.05); however, these factors significantly affected BPA levels in non-sterilised cans.