International Standards in Corrosion of Metals and Alloys. The Activities of ISO/TC 156 “Corrosion of Metals and Alloys”

We continue to inform readers about the activities of the Technical Committee Corrosion of metals and alloys of the International Organization for Standardization (ISO/TC 156). The work program of the Committee for 2000 is given. The scheme of the participation of specialists in corrosion in the activity of the Committee, as well as the procedure of submitting draft standards for the development as International standards, is shown.     

关于GB/T 24000-ISO 14000系列标准

阐述了ISO14000系列标准产生的背景、已发布的5个标准简况、ISO／TC207正在起草的国际标准及其发展趋势；介绍了实施ISO14000系列标准的作用和意义以及我国推行ISO14000系列标准的原则和计划；指出了ISO14000系列标准与ISO9000族标准的关系。     

Long‐term atmospheric corrosion monitoring

The paper presents the analysis of corrosion rates of carbon steel, zinc, aluminium and copper after long‐term exposition as a function of time and environmental parameters. All experimental methodologies on the test sites were carried out according to ISO standards. The analysis of trends of environmental pollution and corrosion rates was performed for one year exposition of metals on three sites (urban/industrial, urban and rural atmosphere) in Poland. The corrosivity changes as a result of a reduction of corrosion rates of metals used are relatively smaller then the reduction of pollution. By using the equation C = Atⁿ, where C – corrosion rate after t years, A – corrosion rate after the first year of exposition, and results of long‐term corrosion rates, exponent n was determined for the different metals and sites from log‐log plots.     

压铸工业如何走可持续发展道路——试论ISO14000的贯彻

阐述了可持续发展的含义 ;介绍了ISO14 0 0 0系列环境管理标准内容 ,并作了重点分析 ;列出了在压铸企业中有关环境污染问题 ;提出了如何积极地贯彻ISO14 0 0 0中的规范内容     

3种有色金属在沈阳地区的大气腐蚀规律

通过Cu，Zn，A1在沈阳地区的大气暴露实验，总结了3种金属的大气腐蚀规律，并讨论了干沉降和湿沉降对金属的大气腐蚀影响。结果表明：Cu，Zn的腐蚀深度与暴露时间呈线性关系；A1的腐蚀深度与暴露时间呈幂指数关系。利用X射线衍射仪和扫描电镜对腐蚀产物的结构和形貌进行分析，并讨论了3种金属大气腐蚀产物的形成过程。     

Dependence of the Protective Concentration of a Mixture of Inhibitors from Several Reaction Series on the Polarities of Substituents in Their Molecules

Protective concentrations of mixtures of inhibitors from several reaction series (RSs), which decrease the corrosion rates a given number of times, are exponentially dependent on the sum of partial polarities of substituents in compounds belonging to the chosen RSs, provided that the total concentration of compounds for each RS is constant. The dependence is linearized in semilogarithmic log C _prvs – m coordinates.     

The kinetics and mechanism of catastrophic oxidation of metals

A set of independent methods has been used to study the catastrophic oxidation of copper in the system Cu–Me_xO_y (where Me is Bi, W, Mo, or V). Two stages of the catastrophic oxidation have been revealed: a rapid stage (K10^–4 kg² m^–4 sec^–1) and a super rapid stage when the metal is oxidized within1–5 sec. The weight ratios of metal to oxidizer and the partial oxygen pressure for the superrapid copper oxidation have been established. The mechanism of the catastrophic oxidation of metals is considered.     

Outdoor-indoor corrosion of metals in tropical coastal atmospheres

Results of indoor and outdoor atmospheric corrosion tests conducted during a long period of time at Cuba and Campeche (Mexico) indicated very high corrosion rates at both sites which have humid-tropical marine climate. We found that the outdoor corrosivity ranges from C3 to >C5 according to ISO 9223 nevertheless metals exposed to sheltered conditions presented higher corrosion rates compared to outdoors, whereas in closed (indoor) environments the corrosion rate significantly decreased. It is recommended to define an additional level of corrosivity for tropical coastal atmospheres in outdoor and sheltered conditions as corrosion depends on the geographical position and exposure conditions.     

Effect of preoxidation and Ti or Hf additions on the corrosion behavior of Fe-23Cr-5Al alloys in Ar-10SO2 at 1200 K

An Fe-23Cr-5Al alloy and those containing 0.21% Ti or 0.12% Hf were cyclically corroded in flowing Ar-10SO₂ gas under atmospheric pressure and in a temperature range varying from room temperature to 1200 K. The corrosion kinetics were assessed by gravimetry, while morphological examinations were carried out using x-ray diffractometry, scanning electron microscopy, and microanalysis. Similar corrosion tests and examinations of the corrosion products were performed for the specimens preoxidized at 1200 K for 20 ksec in pure oxygen under atmospheric pressure. The main corrosion product under all the experimental conditions was -alumina, growing mainly outward in the form of thin needles. Many voids formed beneath the adherent scales. The degree of outward growth decreased by the additives. Partial spallation and formation of scales repeated on the base alloy, resulting in continuous mass losses. The addition of Ti prevented scale spallation, resulting in gradual mass gains; whereas the addition of Hf resulted in poorly adherent scales, under which grooving at alloy grain boundaries and void formation inside the grains occurred. Preoxidation resulted in the formation of adherent scales on all the alloys; however, with increasing corrosion cycles, the outward growth of the oxide became significant. Penetration of sulfur to the substrate under the adherent scale took place.     

Exfoliation corrosion of aluminum alloys and their protection by coatings with metal-filled primers

Exfoliation corrosion (EC) is shown to represent a special type of stress corrosion which develops under the surface of aluminum high-alloyed alloys like 16T and B95T1. Protection against EC by using common paint coatings (PCs) is ineffective. Indoor tests demonstrate that EC can be almost completely suppressed by using PCs with zinc-filled primers (ZFPs). After 2-year tests in sea tropics, common PCs do not prevent the appearance and development of EC. At the same time, samples protected by PCs that involve ZFP EP-057 demonstrate the total absence of EC including bare surface areas up to 5 and even 10 mm wide where the coating has failed. Similar results are obtained in 6-year tests in north sea atmosphere. Potentiodynamic studies of different protection schemes confirm the electrochemical protection mechanism of aluminum alloys against EC by using ZFPs. It is shown that ZFPs can also be used during maintenance works. The advantages of metal-filled primers based on polyurethane over those based on epoxy resin are shown.Translated from Zashchita Metallov, Vol. 41, No. 1, 2005, pp. 40–51.Original Russian Text Copyright © 2005 by Sinyavskii, Kalinin, Gladyshev, Yakimova.     

Atmospheric corrosion of galvanized steel and aluminium in marine and marine‐industrial environments of Saudi Arabia

Three‐year exposure programme was carried out in Saudi Arabia at nine test stations with different climatic and pollution conditions. The aim of this study was to evaluate the joint effect of atmospheric pollutants (Cl^? and SO₂), relative humidity (RH) and temperature (T) on the atmospheric corrosion of galvanized steel (GS) and aluminium (Al). Corrosion rates of the two metals have been obtained by loss of weight after 1, 2 and 3 years exposure. The composition of the corrosion products formed on the specimens was identified by X‐ray diffraction analysis. A classification of the atmospheric corrosion aggressivity of the test sites based both on environmental data and corrosion rate measurements was made according to ISO 9223. In some regions, it can be found that corrosion rate values exceed those established by the ISO standard.     

Atmospheric corrosion in subtropical areas: influences of time of wetness and deficiency of the ISO 9223 norm

In this paper the first results of the study of the corrosion of exposed metals to the action of saline atmospheres in subtropical areas (Canary Islands, Spain) are presented. During three years, carbon steel, zinc and copper sheets have been exposed to the action of different atmospheres in 35 test sites distributed in the western islands of the Canarian Archipelago, located in front of the African continent, which are characterized by a soft climate and seasonal rains. Corrosion rates of the three metals have been obtained by lost of weight. Time of wetness and deposition rates of atmospheric pollutants (i.e. Cl⁻ and SO₂) have also been determined. Applying the standard ISO 9223 norm aggressiveness of the atmospheres corresponding to the different test sites has been determined. In the whole region it can be frequently found corrosion values that exceed those established by the Standard ISO 9223 norm. Therefore, the scale of the aggressiveness to the corrosion was enlarged in order to include coastal areas of the tropical and subtropical regions.     

Voltammetric current oscillations due to general and pitting corrosion of tantalum: Implications for electrochemical-mechanical planarization

Anodic corrosion of Ta is examined for potential applications in electrochemical-mechanical planarization (ECMP) of diffusion barriers. This strategy involves electro-oxidation of Ta in the presence of (or Br⁻) to form mechanically weak surface-oxide films, followed by mechanical removal of the latter. The voltammetric currents exhibit oscillatory behaviour with frequencies that are signature attributes of localised pitting by Br⁻ or general surface corrosion by . SEM, voltammetry, and impedance spectroscopy are used to probe these corrosion mechanisms. Apart from their relevance for ECMP, the results also address certain fundamental aspects of pitting and general corrosion of valve metals.     

The high-temperature corrosion behavior of Nb-Al alloys in a H2/H2S/H2O gas mixture

The corrosion behavior of pure Nb and three Nb Al alloys containing 12.5, 25, and 75 at.% Al was studied over the temperature range of 800–1000°C in a H₂/H₂S/H₂O gas mixture. Except for the Nb-12.5Al alloy consisting of a two phase structure of -Nb and Nb₃Al, other alloys studied were single phase. The corrosion kinetics followed the parabolic rate law in all cases, regardless of temperature and alloy composition. The parabolic rate constants increased with increasing temperature, but fluctuated with increasing Al content. The Nb-75Al alloy exhibited the best corrosion resistance among all alloys studied, whose corrosion rates are 1.6–2.2 orders of magnitude lower than those of pure-Nb (depending on temperature). An exclusive NbO₂ layer was formed on pure Nb, while heterophasic scales were observed on Nb-Al alloys whose compositions and amounts strongly depended on Al content and temperature. The scales formed on Nb-12.5Al consisted of mostly NbO₂ and minor amounts of Nb₂O₅, NbS2, and -Al₂O₃, while the scales formed on Nb-25Al consisted of mostly Nb₂O₅ and some -Al₂O₃. The scales formed on Nb-75Al consisted of mostly -Al₂O₃ and Nb₃S₄ atT 900°C, and mostly -Al₂O₃ , Nb₃S₄ and some AlNbO₄ at 1000°C. The formation of -Al₂O₃ and Nb₃S₄ resulted in a significant reduction of the corrosion rates.     

Electrochemical and quantum chemical studies of some indole derivatives as corrosion inhibitors for C38 steel in molar hydrochloric acid

A comparative study of 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane) as inhibitors for C38 steel corrosion in 1 M HCl solution at 25 °C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors. The OCP as a function of time were also established. Cathodic and anodic polarization curves show that norharmane and harmane are a mixed-type inhibitors. Adsorption of indole derivatives on the C38 steel surface, in 1 M HCl solution, follows the Langmuir adsorption isotherm model. The values were calculated and discussed. The potential of zero charge (PZC) of the C38 steel in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. Raman spectroscopy confirmed that indole molecules strongly adsorbed onto the steel surface. The electronic properties of indole derivates, obtained using the AM1 semi-empirical quantum chemical approach, were correlated with their experimental efficiencies using the linear resistance model (LR).     

浅谈贯彻ISO9000系列标准及进行内部审核的必要

本文对贯彻ＩＳＯ９０００标准及进行内部审核的必要性作了阐述。     

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 企业实验室建设及管理当中涉及到ISO/IEC17025与 ISO9000两套理论体系、两套制度，企业实验室在实际运行中要同时满足两套体系的要求。     

Investigation on lead corrosion products in sea water and in neutral saline solutions

A method was developed to characterize and quality lead corrosion products in sea water and in saline neutral solutions. This method is based on selective dissolution of various compounds, using suitable reagents (methanol, glycine, potassium nitrate etc.) and on subsequent chemical analysis of the various dissolved elements. The findings are then verified by X-ray diffractometer analysis. This method was used for an examination of the corrosion products adhering to a lead plate of a Roman ship wrecked in the Gulf of Toulon about two thousand years ago. The following corrosion products were determined: These products were compared with those obtained on sea water immersed lead specimen. In the latter case, the products were the following: The difference between the two test specimen is deemed to be due to the known formation caused by bacterial fouling processes (desulfovibrio desulfuricans) of hydrogen sulphide in marine sediments which, by altering the pH value, also alter the equilibrium of the CO₃^??-HCO₃^?-CO₂-SO₄^??? HSO₄^? systems thus affecting the differentiated formation of the corrosion products. Lead, despite its improved corrosion resistance in various environments as compared with other normally used metals (e.g. iron), is not so commonly employed because of its poor mechanical properties (deformation, grain coarsening, brittleness [1], etc.) so that it is only used for certain structures like pipings or coverings (roofs, chemical vats etc.) not exposed to strong mechanical stresses. These applications were common even in ancient times, when the Romans already covered their hulls with lead plates because they did not corrode easily and thus had a long life.     

Long-term forecast of corrosion mass losses of technically important metals in various world regions using a power function

An analysis of the results of corrosion tests on flat and helix specimens made of technically important metals carried out within the ISO CORRAG program is given. Stochastic relationships between coefficient n in the power function, which characterizes the protective properties of the corrosion products, and the limiting corrosion rate α, with the corrosivity of each type of atmosphere were found. A forecast of corrosion losses for a period of up to 50 years was given using the linear function in the stationary stage, a power function, and limiting corrosion rate values α. The reliability of the forecasts was estimated.