British Corrosion Journal

AbstractAbstractThe action of 1-hydrox yethylidene-1, 1-diphosphonic acid (HEDP) in combination with zinc ions as a corrosion inhibitor for mild steel in oxygen containing aqueous solutions has been investigated in relation to the presence of different zinc levels, the presence of aggressive anions, and different pH values. The highest inhibition effect was obtained at a 2·7:1 zinc/HEDP molar ratio, corresponding to 60 ppm zinc, and was associated with a significant anodic effect. In the absence of chloride and with no free forms of the inhibitor components, the zinc-HEDP mixture exhibited good protection over a wide range of pH (6·5-9·5). However, in a weakly acidic medium, protection could not be achieved. Calculations based on the dissociation constants of the HEDP and the stability constants of the possible zinc-HEDP complexes showed that this inhibition can be attributed to the presence of the 2:1 zinc-HEDP complex (Zn2H-1L-) at a sufficient level. It is found that this anionic complex can behave as an anodic, passivating, inhibitor at a concentration as low as 0·00015M (20 ppm zinc-32 ppm HEDP mix ture). This passivity is prevented by the presence of sufficient chloride. The critical chloride concentration in these studies is approximately ten times higher than the complex concentration, in molar terms. It is also found that free phosphonate is aggressive and can prevent passivity due to the preferential formation of soluble iron-HEDP complex. The tolerance of the 2:1 complex to free phosphonate is substantially less than to chloride, approx imately equimolar.

H. S. Awad

S. Turgoose

Role of complexes in inhibition of mild steel by zinc–1-hydroxyethylidene-1, 1-diphosphonic acid mixtures

锌-1-羟基亚乙基-1,1-二膦酸混合物对低碳钢抑制作用的复合物作用

AbstractAbstractRuthenium oxide, one of the excellent electrocatalysts having high conductivity and high chemical and thermodynamic stability, has been coated onto the surface of an electrode made from a Al–5 wt-%Zn alloy. The activated aluminium ion was able to diffuse through the porous catalytic hydrophilic layer. Ruthenium oxide coated Al–Zn alloy anodes displayed high open circuit potential and high closed circuit potential during galvanic exposure with mild steel cathodes. A galvanic efficiency as high as 86% with an actual current capacity of 2573 A h kg-1 was achieved. The RuO2 film underwent very little deterioration and a considerable mass of the ruthenium oxide film persisted on the anode surface, even after the electrode size had been reduced to one third of its original size owing to galvanic dissolution. These electrodes are economically efficient, as convenient to prepare, install and use as other conventional electrodes, are tolerable of very aggressive media and highly efficient, even under high galvanic current loads.

S. M. A. Shibli

S. George

V. S. Gireesh

Ruthenium oxide for effective activation of aluminium sacrificial anodes: a new approach

氧化钌有效激活铝牺牲阳极的新方法

AbstractAbstractPhysical scale modelling was employed to examine the effect of reference electrode (RE) location upon the modulations of warship impressed current cathodic protection (ICCP) current output resulting from propeller rotation. A one hundredth scale painted metal model of a frigate hull, fitted with two rotating propellers, was protected by ICCP in sea water diluted to an electrical conductivity one hundredth that of standard sea water. An 'all aft' four anode ICCP configuration was employed, with the RE at one of three locations in the after cut up. Propeller/shaft rotation produced amplitude modulations of ICCP current outputs. The data shows that both the waveform and the magnitude of the modulations were determined by where the RE was sited relative to the propellers. A different output waveform was associated with each RE location. A superimposed 'beat' rhythm was produced only with one position. The RE location also determined not only total current outputs but also the absolute and percentage magnitude of the modulations. Possible mechanisms for the phenomenon and requirements for further studies are discussed.

A. O. Akomah

J. S. Dahele

D. J. Tighe-Ford

Effect of warship impressed current cathodic protection configuration on low frequency current output modulations associated with propeller/shaft rotation

舰船外加电流阴极保护配置对与螺旋桨/轴旋转相关的低频电流输出调制的影响

AbstractFifty three products, mostly carboxylate salts of amines, were evaluated as vapour phase corrosion inhibitors for mild steel. Fifteen compounds showed effectiveness in excess of 90%. Morpholine was the most effective amine and caprylic acid the most effective acid constituent. The effectiveness of ammonium monocarboxylates decreased with increase in the length of the carbon chain of the carboxylic acid. The other carboxylates did not show such a clear trend.

E. Vuorinen

W. Skinner

Amine carboxylates as vapour phase corrosion inhibitors

胺羧酸盐作为气相缓蚀剂

AbstractAbstractThe conventional wisdom in corrosion testing is that the size of the coupon and its perimeter/area ratio (the surface area of the perimeter expressed as a percentage of the total surface area) are important parameters and that these will have an effect on the results obtained. In order to test this proposition, sets of mild steel coupons of the same exposed areas but having different perimeters were immersed in a marine environment. Corrosion mass loss was observed for area/perimeter ratios in the range 3·52-6·03%. Mass loss observations were taken at various times to 12 months. Sets of rectangular coupons of different sizes (50 × 100 mm and 100 × 200 mm) were also immersed. The results indicate that any variation caused by shape or size falls within the expected variability of corrosion at a test location.

R. Jeffrey

R. E. Melchers

Shape and size effects for marine immersion coupons

海洋浸没试样的形状和尺寸效应

AbstractAbstractA study has been conducted of the resistance to corrosion in molten zinc of borophosphate enamels. The melting temperature of the enamels was adjusted by adding the carbonates of alkali metals and alkaline earth metals. Scanning electron microscopy was used to examine solidified interfaces between the enamels and the molten zinc. At low magnification (× 30) no evidence of components from the B2O3-P2O5 enamels was detected by electron probe in the industrially pure zinc near the interface with the enamel, but elemental Zn was found in the initially zinc free B2O3-P2O5 enamels. When the interface was examined at a magnification of 1000 times, it was confirmed by electron probe that no phosphorus from the borophosphate enamel was present in the zinc matrix at a position 60 μm from the interface. The results show that the borophosphate enamels are extremely resistant to corrosion in molten zinc.

M. Zhou

J. Zhang

D. Shu

K. Li

H.J. Ni

W.Y. Zhang

B.D. Sun

J. Wang

Corrosion resistance of borophosphate enamels in molten zinc

硼磷酸盐搪瓷在熔融锌中的耐腐蚀性能

AbstractAbstractThe electrochemical behaviour of two copper-nickel alloys in solutions containing the carbonate ion has been investigated by cyclic voltammetric, potentiodynamic, and current/time transient techniques. Among the variables studied were alloy composition, stepwise increasing potential, scan rate, carbonate ion concentration and temperature. The composition of the compounds formed on the alloy surface during the anodic polarisation was characterised using X-ray diffraction analysis. The dissolution behaviour of the alloy consists of two potential regions separated by the critical potential Ecrit. The first potential region involves the selective dissolution of the more active constituent, nickel, and the appearance of one anodic peak A1 as a result of the formation of Ni(OH)2on the alloy surface. The second potential region relates to the simultaneous dissolution of copper and nickel. This region was characterised by the appearance of four anodic peaks A2, A3, A4, and A5, which are related to the formation of Cu2O, {CuO and Cu(OH)2}, CuCO3-Cu(OH)2 composite, and NiOOH, respectively. Potentiostatic current/time transients showed that the formation of Ni(OH)2, Cu2O, CuO, Cu(OH)2, CuCO3-Cu(OH)2 and NiOOH layers involves a nucleation and growth mechanism under diffusion control.

Ayman M. Zaky

Fawzi H. Assaf

S. S. Abd El Rehim

B. M. Mohamed

Electrochemical behaviour of copper-nickel alloys in stagnant Na2CO3solutions

铜镍合金在静止Na2CO3溶液中的电化学行为

AbstractAbstractThe test results from an earlier investigation by the author on the mechanical behaviour of a low nickel nickel-copper alloy exposed to a solution of 3·5%NaCl + 10%MgCl2 with and without ammonia indicated that the presence of 1% ammonia alters the failure mode and affects the load bearing capacity of the material. In the present investigation, further tests have been conducted on the same alloy to study its mechanical/corrosion behaviour on exposure to an aqueous solution of ammonia in comparison with exposure to a similar solution of ammonia containing 3·5%NaCl + 10%MgCl2. A constant displacement rate of 9·6 × 10-3 μ m s-1 was used and the concentration of ammonia was maintained at 5%. On exposure to the 5% aqueous ammonia solution, the mechanical properties of the alloy were degraded significantly and the material exhibited a brittle stress corrosion type of failure. However, on exposure to 5% ammonia in the presence of 3·5%NaCl + 10%MgCl2, there was less change in failure mode relative to that in air and a significant improvement in the mechanical properties of the material compared with those in aqueous ammonia. This indicates that the presence of MgCl2 and/or NaCl can be beneficial when low nickel copper alloys are exposed to ammonia. This paper presents the experimental results and observations from the recent tests, and discusses the relative roles of ammonia and NaCl/MgCl2 in determining the mechanical properties and modes of failure in a low nickel content copper-nickel alloy.

D. C. Agarwal

Stress corrosion in copper–nickel alloys: influence of ammonia

铜镍合金中的应力腐蚀：氨的影响

Potentiodynamic polarisation curves have been used to evaluate the corrosion performance of 1008 carbon steel coated with hybrid (inorganic-organic) and mixed oxide coating systems deposited by dip coating. Several coatings have been prepared by the sol-gel method, using metallic alkox ides, such as tetraethylorthosilicate, aluminium isopropoxide, and zirconium propoxide, and polymers like allyl methacrylate (AMA) and polymethylmethacrylate (PMMA), together with zirconium dioxide (ZrO2) and silicon and aluminium oxides (SiO3-Al2O3). The aqueous test solutions included hydrochloric acid (HCl), sodium chloride (NaCl), and sulphuric acid (H 2SO4) at various concentrations (0·1, 0·5, and 1M). Scanning electron microscopy was used to examine the coatings following testing. The results have shown that SiO2-Al2O3 based coatings are not beneficial for corrosion protection in HCl, but are of value in the other aqueous media. In 1·0M HCl, the best protection was offered by a hybrid SiO2-ZrO2-poly(methylmethacrylate-allyl methacrylate) (P(MMA-AMA)) coating. In NaCl, the best results, were generally obtained with SiO2-Al2O3 and SiO2-ZrO2-P(MMA-AMA) coatings. Similarly, in H2SO4, the best results were generally displayed by the SiO2-Al2O3 and SiO2-ZrO2-P(MMA-AMA) coatings. The corrosion behaviour of the coatings is discussed in terms of the integrity and stability of the film.

G. Carbajal De La Torre

R. Nava Mendoza

M. A. Espinosa-Medina

A. Martinez-Villafañe

J. G. Gonzalez-Rodriguez

V. M. Castaño

Corrosion protection of 1008 carbon steel by hybrid coatings

1008碳钢的混合涂层腐蚀防护

AbstractThe synergistic inhibition of aluminium bronze corrosion by 4-phenyl semicarbazide hydrochloride (PSC) and the iodide ion in HCl of pH (1·8-2) at 60°C has been assessed by polarisation studies, Tafel plots, X-ray photoelectron spectroscopy and Auger electron spectroscopy. The addition of 0·01M KI to 0·01M PSC improved the inhibition efficiency from 86 to 94% owing to the formation of a CuI-PSC complex which is more compact, protective and hard than the film formed in the absence of iodide. The inner layer of this protective film contains a small amount of aluminium oxide, which increases the protective nature of the film and retards the dissolution of the underlying aluminium bronze.

A. A. El Warraky

A. E. El Meleigy

Electrochemical and spectroscopic investigation of synergestic effects in corrosion inhibition of aluminium bronze Part 1 – In pure HCl

铝青铜腐蚀抑制协同效应的电化学和光谱研究 第1部分 - 在纯HCl中

Publication Information	Publisher: Maney Publishing，Publishing cycle: ，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 1965，Proportion of original research papers: ，Self Citation Rate:， Gold OA Rate:

British Corrosion Journal

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