Anticorrosive and physicochemical properties of modified phosphate pigments

Abstract Many studies have been carried out in the direction of improvement of the effectiveness of commonly utilized phosphate corrosion inhibitors. For this purpose various types of modifications are realized, e.g. introduction of different cations to the pigment composition or replacement of phosphate anions with others. In the presented work, anticorrosive pigments containing calcium hydrogen phosphate, and/or calcium hydroxyphosphate, and calcium molybdate were obtained. The phase and chemical composition and the oil absorption number of those materials were determined. The anticorrosive properties were investigated by an electrochemical noise method. The obtained results were compared with previously published studies concerning pigments containing (NH4)3Al2(PO4)3 and/or AlPO4, and CaMoO4. It was found that the pigment containing only calcium molybdate(VI) is not an effective corrosion inhibitor. However, the pigments comprising a mixture of CaHPO4 and CaMoO4 exhibited good anticorrosive properties and they were characterized by higher effectiveness in the corrosion protection than compared materials.

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Assessing of New Coatings for Iron Artifacts Conservation by Recurrence Plots Analysis

Coatings ◽

10.3390/coatings9010012 ◽

2018 ◽

Vol 9 (1) ◽

pp. 12 ◽

Cited By ~ 4

Author(s):

Paola Roncagliolo Barrera ◽

Francisco Rodríguez Gómez ◽

Esteban García Ochoa

Keyword(s):

Cast Iron ◽

Statistical Analysis ◽

Corrosion Inhibitors ◽

Electrochemical Noise ◽

High Humidity ◽

Recurrence Plots ◽

Surface Corrosion ◽

Temporary Protection ◽

Protection Method ◽

Iron Artifacts

Cast iron has stood for centuries of invention. It is a very versatile and durable material. Coating systems are a low-maintenance protection method. The purpose of this research is to increase the Paraloid coating’s resistance when applied to iron in high humidity atmospheres, with the addition of caffeine (1,3,7-dimethylxanthine) and nicotine (S)-3-(1-methylpyrrolidin-2-yl) pyridine as corrosion inhibitors; the resistance of protection versus exposure time will be evaluated by using electrochemical noise. A statistical analysis of the electrochemical noise signals was carried out. Recurrence plots were used as a powerful tool in the analysis to complement the data obtained and they predicted the evaluation of coatings behaviors performance versus time. The outcomes show that the addition of inhibitors increases and improves the performance as a temporary protection of Paraloid and that protection in high relative humidity was improved. Recurrence plots and parameter quantification show the variances in the surface corrosion dynamics.

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Electrochemical Noise Analysis for Different Green Corrosion Inhibitors for Copper Exposed to Chloride Media

Portugaliae Electrochimica Acta ◽

10.4152/pea.201704201 ◽

2017 ◽

Vol 35 (4) ◽

pp. 201-210 ◽

Cited By ~ 6

Author(s):

A M Nagiub

Keyword(s):

Corrosion Inhibitors ◽

Electrochemical Noise ◽

Noise Analysis ◽

Green Corrosion Inhibitors

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Research on Inhibiting Performance of Compound Corrosion Inhibitors Based on Nitrite

Advances in Civil Engineering ◽

10.1155/2021/6655080 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Bing Yi ◽

Jianmin Wang ◽

Liyu Feng ◽

Yilin Song ◽

Junzhe Liu ◽

...

Keyword(s):

Corrosion Inhibitors ◽

Concrete Surface ◽

Inhibitory Effect ◽

Test Methods ◽

Hydrogen Phosphate ◽

Composite Repair ◽

Inhibition Effect ◽

Rebar Corrosion ◽

Macrocell Corrosion ◽

Low Dosage

To solve rebar corrosion in existing concrete structures, two test methods, adding corrosion inhibitors into concrete and applying corrosion inhibitors on the existing concrete surface by brushing and pouring and composite repair, combined with natural potential, XRD and SEM, were used to comprehensively evaluate the performance of nitrite-based compound corrosion inhibitors. The research results show that nitrite has a better inhibitory effect than phosphate, and when the respective mass fraction of hydrogen phosphate and sodium nitrite is about 1.5%, the rust inhibition effect is the optimum. Brushing, perfusion, and composite repair can all play a good role in inhibiting corrosion of which composite repair is the best. The addition of phosphate can improve the macrocell corrosion caused by the low dosage or uneven distribution of nitrite.

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Experience Using Electrochemical Noise for Testing Green Corrosion Inhibitors

10.2118/205475-ms ◽

2021 ◽

Author(s):

Douglas J Mills ◽

Joshua Zatland ◽

Nicola M Everitt

Keyword(s):

Weight Loss ◽

Crevice Corrosion ◽

Corrosion Inhibitors ◽

Electrochemical Noise ◽

Banana Peel ◽

Biomass Waste ◽

Plant Materials ◽

Complementary Interactions ◽

Static Conditions ◽

Green Corrosion Inhibitors

Abstract ‘Green’ corrosion inhibitors derived from plant materials provide environmentally friendly alternatives to conventional corrosion inhibitors. They are also much cheaper if using a biomass waste stream or abundant plant material as the source material. There are many examples in literature of different trials, from henna leaves to celery seeds to banana peel. Although it is known that extracts contain electron-rich polar atoms such as N, O, S and P which make them potentially effective inhibitors, it is difficult to predict on a molecular basis what will work well and what will not, since many interacting factors may be at play in complementary interactions. To assist in predicting the inhibition efficiency of inhibitors under varying conditions and choosing the most effective, what is needed is a short-term test which will obviate the need for tedious weight loss experiments. The Electrochemical Noise Method (ENM) uses the natural fluctuations which arise during electrochemical activity to gain information about the corrosion process. Using ENM is quick and non-intrusive method which makes it ideal for screening. Hence a rig has been designed and manufactured which allows for measurement to be made in stirred as well as static conditions and minimises the occurrence of crevice corrosion at the electrodes. Crevice corrosion is a hazard for ENM electrodes when trying to make a comparison with corrosion inhibition calculated using the standard weight loss measurement after immersion (WLM) method. For these preliminary trials we are exploring corrosion of mild steel in HCl in both stirred and unstirred conditions at room temperature. Results are presented comparing ENM measurements with conventional WLM for both Propargyl Alcohol (a conventional industrial corrosion inhibitor) and broccoli extract. Our results suggest that stirring does not make any difference to the noise measured in ENM. The amount of material lost calculated by ENM and WLM (Rn and weight loss values) can be directly compared and show close comparison. It seems likely that as a way of assessing inhibitors quickly (which is particularly important in the testing of "green" inhibitors) that this ENM approach has a lot to offer.

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