Aminomethylenphosphonsäuren als Korrosionsinhibitoren für Aluminiumpigmente in wäßrigen Medien

Aminomethylenephosphonic acids as corrosion inhibitors for aluminum pigments in aqueous media Flakelike aluminum pigments (aluminum content >99.5%) are corroded in aqueous alkaline mixtures of water and butyl glycol. Aminomethylenephosphonic acids inhibit this corrosion reaction. The temporal progress of the corrosion is determined by volumetric analysis of the evolved hydrogen. Direct comparison of aminomethylenephosphonic acids with analogous aminomethylenecarboxylic acids shows that the phosphonic acid group inhibits the corrosion significantly better than the carboxylic group. The actual corrosion inhibitors are in both cases (soluble) aluminum(III)-chelates, which are formed by a chemical reaction of the aminomethylenphosphonic resp.-carboxylic acids with the aluminum surface. This is proved by measuring the concentration of dissolved aluminum(III) in the corrosion medium with the help of atomic absorption spectroscopy and by using aluminum(III)chelates as corrosion inhibitors.     

Korrosionsuntersuchungen an nichtrostenden,austenitischen Stählen im System Essigsäure/Essigsäureanhydrid

Corrosion tests of austenitic stainless steels in the system acetic acid/acetic anhydride The corrosion behaviour of the austenitic stainless steels X6 CrNiMoTi 17 12 2 (mat.no. 1.4571, AISI 316 Ti) and X2 NiCrMo-Cu 25 20 5 (mat.no. 1.4539, alloy 904 L) was investigated by immersion tests of welded specimens in acetic acid and acetic anhydride and in mixtures thereof, as well. The tests were carried out at 80°C and at the boiling point of the test solutions. The test equipment was either open to the atmosphere or the mixtures were deaerated with nitrogen. The tests show that in the presence of air the mixtures are more corrosive than the neat media. At 80°C in aerated solutions only alloy 904 L (mat.no. 1.4539) performed well, except in a mixture of 70% acetic acid and 30% acetic anhydride. At the boiling point of the test solutions the corrosive attack on both stainless steels increases considerably; the corrosion rates are in the range of 1 mm/a (1.4571) and 0.6 mm/a (1.4539). Deaeration with nitrogen decreases the corrosivity of the solutions to the stainless steels. Electrochemical tests show the detrimental influence of acetic anhydride to the passivation process of stainless steels tested in glacial acetic acid.     

Korrosion von Zinkpigmenten im alkalisch wäßrigen Medium

Corrosion of zinc pigments in alkaline aqueous medium Zinc pigments corrode in an alkaline mixture of water and butyl glycol in the ratio 9 : 1 by the evolution of hydrogen. The corrosion rate decreases in the series flakelike non-leafing zinc pigment > flakelike leafing zinc pigment >spherical zinc dust. The relative high stability of the zinc dust can he explained by its low surface area. The chemical structure of the base which is used for adjusting the pH value has a significant influence on the corrosion rate of the flakelike leafing zinc pigment; the corrosivity falls in series ammonia > sodium hydroxide > 2-(dimethylamino)ethanol > triethylamine. The corrosion rate of the flakelike non-leafing zinc pigment depends only on the pH value and not on chemical structure of the examined bases. The determination of the concentrations of dissolved zinc(II) in the corrosion media by atomic absorption spectroscopy shows that the corrosion rate grows with increasing solubility of zinc(II) approximately.     

高效低膦复合型缓蚀阻垢剂的研制

Taking organic phosphonic acid, organic phosphono carboxylic acid, surfactant, and sale with zinc as main material, a new organic multicomposite scale and corrosion inhibitor was complexed. Petrochemical company after the circulating cooling water in the depth of treatment as the media, the corrosion inhibition rate and scale inhibition rate were determined by rotation coupon corrosion and calcium carbonate precipitation methods, then six kinds of composice scale and corrosion inhibiton formnala were choisen. The comparison results to merchant products show that the corrosion inhibiton rate and scale inhibition rale of six corrosion and scale inhinbitors are more than 95% , and scale inhibition rale for calcium carbonale is 95% or more. The corrosion inhibition and scale inhibition performances of the high efficent and environmental protection inhibition are more excellent than that of merchant products.     

Die Korrosionseigenschaften von feuerverzinktem Stahlblech in warmen weichen Wässern mit CO2- und/oder O2-Spülung

Corrosion properties of hot dipped galvanized steel plating in soft warm water with CO₂ and/or O₂ flows Research has been carried out on hot dipped galvanized plates in warm (70° C) diluted NaCl and Na₂SO₄ solutions with a conductivity of 300 μ S/cm at room temperature as a function of the composition of the flowing gas. When exposed to oxygen, the specimen plates show marked pit corrosion already after a few days. An attack on the zinc layer is followed by a local attack on the bared surface of the steel. Cathodic protection by sacrificial magnesium anodes, whilst reducing the corrosion rate, gives rise to needle-prick pitting corrosion on the zinc layer. The only means of stopping corrosion completely is the application of external current protection with several amps pr. sq. metre. With carbonic acid flow, the zinc layer is removed homogeneously, the corrosion rate being of the order of 0.07 μ/h. In the case of gassing with a 1 : 1 mixture of carbonic acid and oxygen, a corrosion-inhibiting covering layer of hydrozincite is formed. Hot dipped galvanized specimens with a zinc cover of approx. 47 μ showed no signs of corrosion after 4350 hours. In no case was it possible to observe a reversal of the potential of the iron-zinc element. The pitting corrosion encountered with oxygen flow must be ascribed to the effect of Evans' elements.     

Ein Beitrag zum Korrosionsverhalten von austenitischem 17-12-2 CrNiMoTi-Stahl in siedenden Essigsäurelösungen - Betriebserfahrungen und Laborversuche

A contribution concerning the corrosion behaviour of austenitic 17-12-2 CrNiMoTi stainless steel in boiling acetic acid solutions - Service experience and laboratory tests Service experience of acetic acid processing industry shows that X 6 CrNiMoTi 17-12-2 stainless steel (similar to AISI type 316 Ti) can be used as construction material for handling concentrated boiling acid without facing corrosion problems if, in the medium, dissolved oxygen and small amounts of water are present, and if chloride ions are virtually absent. In laboratory tests performed on X 6 CrNiMoTi 17-12-2 stainless steel in acetic acid of 118°C containing variable extents of impurities, the steel exhibited passive behaviour in cases where the chloride ion concentration was less than 1 ppm and, at the same time, water amounts to some few tenths of a percent. The exact value of the water content necessary to achieve passivity depends on the concentration of formic acid the presence of which, at least in traces, is unavoidable. In anhydrous acetic acid, the steel corrodes in its active state, and dissolved oxygen increases the corrodes in its active state, and dissolved oxygen increases the corrosion rate. If chloride ion concentration is 1 ppm or higher the otherwise passive steel undergoes localized corrosion and the attack mostly follows crystallographic orientations. In aerated boiling mixtures of acetic acid and anhydride, the steel is boiling mixtures of acetic acid and acetic anhydride, the steel is severely corroded until the portion of anhydride reaches 70%. Beyond this, corrosion rate steeply decreases. Practically no corrosion could be found in 97% acetic anhydride.     

Korrosionsuntersuchungen an ausgewählten metallischen Werkstoffen im System Essigsäure/Esigsäureanhydrid

Corrosion tests of selected metallic materials in the system acetic acid/acetic anhydride The corrosion behaviour of the ferritic austenitic stainless steels X2 CrNiMoN 22 5 (UNS S31803) and X2 CrNiMoN 25 7 4 (UNS S32750), the nickel base alloy NiMo16Cr16Ti (alloy C-4) and the titanium grades Ti2 (Grade 2) and Ti2Pd (Grade 7) was investigated by immersion tests in boiling mixtures of acetic acid and acetic anhydride in the presence of air. All materials tested were corrosion resistant in acetic acid and acetic anhydride but were corroded rapidly by the mixtures with a corrosion loss up to 1 mm/a, except the nickel base alloy (alloy C-4). It was corrosion resistant in all solutions with a corrosion loss not exceeding 0.01 mm/a. Electrochemical tests show that all materials tested exhibit stable passivity in glacial acetic acid and active corrosion in the presence of 10% acetic anhydride.     

Oberflächenbehandlung als Korrosionsschutzmaßnahme von nichtrostenden Stählen

Surface treatment as corrosion protection measure of stainless steels The pickling behaviour of several stainless austenitic steels and of one steel with ferritic/austenitic grain structure were investigated in pickling solutions of different compositions based on hydrofluoric acid. Because of uncertainties in practical applications, the influence of temperature, time and acid content on the mass loss is of high interest. In another series of experiments, aqueous solutions of citric acid were tested for their suitability as pickling chemicals for the materials X 6 CrNiTi 18 10 (AISI 321) and X 6 CrNiMoTi 17 12 2 (AISI 316 Ti). Finally, the pickling procedures based on nitric acid/hydrofluoric acid mixtures were compared with mechanical cleansing methods and with pickling procedures based on aqueous citric acid solutions as well, to elucidate their influence on the corrosion resistance of the treated materials. The valuation followed a pitting corrosion test in sodium chloride solutions of different concentrations after Herbsleb and Schwenk. Pickling with hydrofluoric acid solutions is superior to other cleansing procedures, if corrosive environments are present. The ecologically beneficial citric acid solutions are only able to remove the annealing colours from stainless steels.     

Korrosion und Korrosionsinhibierung von Aluminiumpigmenten im alkalisch wäßrigen Medium

Corrosion and inhibition of corrosion of aluminium pigments in alkaline aqueous medium Flakelike aluminum pigments (Al-content > 99.5%) were corroded in an aqueous alkaline mixture of water and butyl glycol in the ratio 9: 1. Chelating agents like citric acid or polyacrylic acid inhibit this corrosion reaction. The temporal progress of the corrosion reaction can be determined by volumetric analysis of the evolved hydrogen and furthermore, with addition of the corrosion inhibitors, by measuring the electrical conductivity of the solution. The corrosion reaction consists essentially of two steps:

• 1 In the latency period no or only little corrosion takes place; during this, time the protective layers (normal oxide layer or layers reinforced by reaction products of inhibitor and aluminum) were dissolved.
• 2 After that the actual corrosion reaction takes place.

It was proved that changes of the pH-value or addition of corrosion inhibitors only influence the duration of the latency period; after that period the rate of the corrosion reaction is nearly independent from the examined conditions.     

工业酸性废水对CuZnAl形状记忆合金腐蚀的影响

采用动电位线性极化法和全浸挂片的方法,并借助电子探针对腐蚀后的合金进行定点分析,研究了以工业酸废水溶液为介绍,ＣｕＺｎＡｌ形状记忆合金腐蚀的影响。结果表明,ＣｕＺｎＡｌ形状记忆合金经淬火后后在马氏体状态下使用时,在工业酸性废水中的腐蚀速率与铸态和退火态合金相比大大降低。     

油田采出水处理复合阻垢缓蚀剂的研究

目的制备一种高效、复合型的油田采出水处理阻垢缓蚀剂。方法以二己烯三胺五亚甲基膦酸、磺酸基共聚物和钨酸钠为原料复配成复合阻垢缓蚀剂,通过静态阻垢试验和动态腐蚀试验,研究复合阻垢缓蚀剂的防垢和缓蚀效果与其质量浓度的关系,考察絮凝剂、杀菌剂及缓蚀剂等水处理剂对防垢效果的影响。结果在油田采出水处理中,阻垢缓蚀剂最佳质量浓度为30 mg/L,此时的阻垢率>95%,腐蚀速率为0.0696 mm/a。油田采出水中过量的絮凝剂及季铵盐1227杀菌剂会造成阻垢率降低,咪唑啉缓蚀剂对阻垢率有增效作用,异噻唑啉酮杀菌剂对阻垢率影响较小。结论该复合阻垢缓蚀剂生产制备简单,阻垢和缓蚀性能优良。     

Zur Korrosion von Kupferwerkstoffen in Tetrachlorkohlenstoff

Corrosion of copper base materials in carbon tetrachloride Copper (OFHC), two copper zinc alloys (CuZn36 and CuZn15), one nickel-copper alloy (NiCu30Fe), the copper tin casting alloy G-CuSn10, and the copper aluminium casting alloy G-CuAl10Fe were immersed in the following boiling media: carbon tetrachloride dried over P₄O₁₀, carbon tetrachlorid saturated with water and two phase mixtures of carbon tetrachloride and water. The individual samples were positioned within the organic phase, within the aqueous phase, within the vapour phase and within the condensated phase, respectively. OFHC copper, NiCu30Fe, CuZn15 and G-CuAl10Fe are corrosion resistant (corrosion rate ≤ 0,01 mm/y) in dry as well as in water saturated CCl₄. The same statement is valid for alloys CuZn36 and G-CuSn10 which show a corrosion rate of approximately 0,02 mm/y within the condensate of CCl₄ saturated with water. All alloys exhibit more or less corrosion within the two phase mixtures. Within the aqueous phase the materials do not prove to be resistant: they are completely dissolved in less than 30 days. Paralle to the corrosion of CuZn36 and G-CuAl10Fe zinc and aluminium, respectively, went into solution. The vapour phase above the carbon tetrachloride-water mixture consisted of over 90% by volume carbon monoxide. This prove that the corrosion of all materials which had been immersed in the aqueous phase was effected by phosgene.     

Über das Korrosionsverhalten von Zink und feuerverzinktem Stahl in erwärmtem Wasser

Corrosion behaviour of zinc and hot dip galvanized steel in warm water The corrosion rate of zinc and hot dip galvanized steel in continuously flowing tap water is but little influenced by water temperature. The slight decrease of the corrosion rate which has been found at higher temperatures (60°C) can be attributed to the preferential formation of zinc oxide at these temperatures, this oxide being less soluble than the hydroxide formed at lower temperatures. The potential shift toward more noble values at higher temperatures does, however, depend from water composition and may eventually start as early as at 35 °C; in certain critical potential ranges the uniform corrosion may even be changed into pitting. Addition of phosphate to the water may reduce either the corrosion rate or it may restrict the potential shift (in this latter case the appearance pitting is prevented). The measurement of the electrode potential (not of the polarization resistance) thus yields information on the danger of pitting corrosion. The quality of the zinc surface seems to be important in those cases where the ZnFe alloy layer protrudes to the zinc surface.     

Wasserstoffinduzierte Spannungsrißkorrosion an unverzinkten und verzinkten Baustählen

Hydrogen induced stress corrosion cracking of non galvanized and galvanized construction steels The processes of atmospheric corrosion and corrosion in collected water which may lead to hydrogen induced stress corrosion cracking of high-strength reinforcing steels in casing tubes before injection with concrete are discussed. Hydrogen uptake during corrosion occurs in weakly acid solutions as well as in neutral or alkaline aqueous solutions. The hydrogen uptake by proton discharge in acid solutions decreases with increasing pH of the electrolyte. Hydrogen can also be absorbed in neutral to weakly alkaline solutions if steels are plastically deformed and water reacts with the fresh iron surface. In alkaline solutions, hydrogen uptake is possible if, at the generally passivated steel surface, localized corrosion (pitting or crevice corrosion), local galvanic cells and a sufficient decrease in the pH of the pit electrolyte occurs. In the case of galvanized steels with damaged zinc layers, hydrogen uptake may result from the cathodic polarization of the free steel surface by zinc dissolution. The absorbed hydrogen interacts with the microstructure of the steels and weakens the bonds between the iron atoms. The influence of the microstructure of high-strength steels on the fracture behaviour is discussed on the basic of the so-called decohesion theory.     

Laboruntersuchungen zur Korrosion von unlegiertem Stahl in Kühlwässern

Laboratory studies on corrosion of unalloyed steel in cooling waters Corrosion tests were carried out in recycle apparatures to prepare cooling-water treatment. The corrosion behaviour of unalloyed steel St 38b-2 in dependence on m-value of water was tested. The corrosion-inhibiting effect of sodium polyphosphate, zinc sulfate, 1-hydroxy-1,1-diphosphonic acid (HEDP) and the trisodium salt of HEDP and polyacrylate and their combinations in water with m-value 1.0–1.5 mmole per litre was tested in comparison with unalloyed steel. The corrosion rate increases strongly below a m-value of 2.2 mmol per litre. Sodium polyphosphate, sodium polyphosphate/zinc sulfate and zinc sulfate-polyacrylate show good protection features in water with m-value 1.0–1.5 mmole per litre. The trisodium salt of HEDP has an insufficient effect.     

膦酸缓蚀剂的合成及其缓蚀性能研究

合成了7种膦酸缓蚀剂。用失重法考察了膦酸浓度及溶液pH值对缓蚀性能的影响,分析了膦酸分子结构与缓蚀性能的关系。通过钢铁表面形态及膜成分分析,证明膦酸是一种吸附型缓蚀剂,在金属表面形成一层致密的憎水保护膜,使腐蚀反应得到抑制。     

Untersuchungen über den interkristallinen Kongrenzenangriff von austenitischen Mangan-Chrom-Stählen durch Wasser und wäßrige Lösungen

Research on intercrystalline grain boundary corrosion of austenitic manganesechrome steels caused by water and aqueous salt solutions Stressed bar specimens of welded and tempered austenitic manganesechrome steel such as as X 40 MnCr 18 and X 22 MnCrNi 885, exposed to sea water, tap water or destilled water, are liable to suffer intercrystalline stress corrosion cracking. The occurrence of intercrystalline corrosion is not necessarily dependent on mechanical tensil stress. In particular, even unstressed specimens exposed to tap or distilled water are liable to show marked intercrystalline corrosion. Additional tensile stress merely has the effect of speeding up the inter-crystalline corrosion. The cause for the intercrystalline corrosion must be seen in the segregation of chrome-rich carbids at the grain boundaries and the consequent reduction in the chrome content within the grain boundary zone. It is possible to prove the segregation of a chrome-rich carbide of the structure M₇C₃ at the grain boundaries of steel X 40 MnCr 18, and the aggregation of a chrome-rich carbide of the structure M₂₃C₆ at the grain boundaries of steel X 22 MnCrNi 885. Through contact with zinc, it is possible to obtain a complete corrosion protection with the manganese-chrome steels investigated. A short circuit with passive austenitic chrome-nickel steels increases the general or selective corrosion rate through anodic polarisation. By adding chromate to the sea water, the corrosion rate is retarded. In tap water, an addition of chromate result in complete corrosion protection.     

复合缓蚀剂在油田采出水中的缓蚀性能研究

目的为了解决油田采出水的腐蚀问题,制备一种复合缓蚀剂,并研究环境因素对缓蚀性能的影响规律,为油田采出水的科学防腐提供理论上的依据。方法采用含磷咪唑啉季铵盐和钨酸钠复配了一种绿色的油田采出水处理复合缓蚀剂,用动态失重法对复合缓蚀剂的缓蚀性能进行了评价,并系统地研究了介质的温度、pH值、矿化度及流速对缓蚀性能的影响。结果油田采出水的温度为55℃、pH值=7.0、流速为2.5 m/s和矿化度为36 g/L时,复合缓蚀剂的最佳投加质量浓度为60 mg/L。该条件下Q235钢的腐蚀速率为0.0269 mm/a,能够满足油田采出水回注的标准要求。腐蚀速率随着缓蚀剂质量浓度的增加而减小,随着采出水温度的升高而增大。采出水的矿化度为32 g/L时,对腐蚀速率的影响最大。采出水的流速为1.2~3.0 m/s和采出水的pH值接近于中性时,其对腐蚀速率的影响较小。结论复合缓蚀剂是一种环境友好型油田采出水处理缓蚀剂,缓蚀性能优良。     

Druck- und temperaturabhängigkeit des Korrosionspotentials von Zink in wässrigen Elektrolyten

Pressure and temperature dependence of the corrosion potential of zinc in aqueous electrolytes In aerated sodium sulfate solution of 50–70 °C the potential of Zn is shifted to more noble values; when carbon dioxidecontaining air is used, however, this shift is less pronounced. In tap water, too, there is such a potential shift which is less pronounced in the absence of carbon dioxide. In some cases, however, there is no potential shift even when water of practically identical composition is used. While thin, adhering layers of corrosion products are formed in water, no compact layers are formed in sodium sulfate solution when cabon dioxide-containing air is used for aeration. In this case there is exfoliation of corrosion products, so that corrosion rapidly proceeds without a visible relation between potential and corrosion rate. As to gas pressure the corrosion potential if practically independent.     

Untersuchungen zur Wirksamkeit des Natriumsalzes der 1-Hydroxyethan-1,1-diphosphonsäure als Inhibitor für Kupferwerkstoffe in Kühlwasser

Investigations on the efficiency of sodium salt of 1-hydroxyethan-1,1-diphosphonic acid as inhibitor for copper materials in cooling water The effect of sodium salt of 1-hydroxyethan-1,1-diphosphonic acid on the corrosion rates of copper, CuZn30, CuZn20A12 and CuNi10Fe1Mn in cooling water was investigated gravimetrically using a recirculating loop. In the presence of zinc ions sodium salt of 1-hydroxyethan-1,1-diphosphonic acid decreases corrosion rates. This phosphonate in connection with zinc salt is a promising inhibitor for CuZn20A12 in cooling water circulating systems.