Adding Corrosion Inhibitors Research Articles

Preparation and characterisation of acrylic–polyurethane-based waterborne anticorrosion coating on galvanised steel

Four water-based organic composite coating solutions were prepared and applied on galvanised sheet samples producing a transparent film of about 5-µm thickness. Their corrosion performances were examined by Tafel polarisation, EIS, salt spray and cyclic corrosion tests. The primary coating formulation contained an acrylic emulsion and polyurethane dispersion mixture together with additives. The corrosion resistance properties of the primary formulation were enhanced by adding nano-ZnO particles, and further improved by adding corrosion inhibitors such as zinc phosphate and sodium phosphate. The final formulation on galvanised samples showed 720 h of salt spray resistance and 90 cycles of cyclic corrosion resistance, SAE J2334. The Tafel and EIS studies indicate that the coating possesses barrier protection properties. The electrolyte penetrates through the coating within 24 h but progress of corrosion depends upon the coating adhesion and its compactness, that is improved significantly by adding nano-ZnO and corrosion inhibitor to the coating formulation.

The Effect of Adding Corrosion Inhibitors into an Electroless Nickel Plating Bath for Magnesium Alloys

In this work, corrosion inhibitors were added into an electroless nickel plating bath to realize nickel-phosphorus (Ni-P) coating deposition on magnesium alloy directly. The performance of five corrosion inhibitors was evaluated by inhibition efficiency. The results showed that only ammonium hydrogen fluoride (NH4HF2) and ammonium molybdate ((NH4)2MoO4) could be used as corrosion inhibitors for magnesium alloy in the bath. Moreover, compounding NH4HF2 and (NH4)2MoO4, the optimal concentrations were both at 1.5 ~ 2%. The deposition process of Ni-P coating was observed by using a scanning electron microscope (SEM). It showed corrosion inhibitors inhibited undesired dissolution of magnesium substrate during the electroless plating process. In addition, SEM observation indicated that the corrosion inhibition reaction and the Ni2+ replacement reaction were competitive at the initial deposition time. Both electrochemical analysis and thermal shock test revealed that the Ni-P coating exhibited excellent corrosion resistance and adhesion properties in protecting the magnesium alloy.

Stimulation of Seawater Injectors by GLDA (Glutamic-Di Acetic Acid)

Summary Seawater is injected to maintain the reservoir pressure that supports the oil production from carbonate and sandstone reservoirs. In certain regions, the seawater contains more than 4,000 ppm sulfate, and the formation contains more than 19,000 ppm calcium; this will cause calcium sulfate precipitation at the reservoir conditions. The precipitate at the reservoir conditions will be anhydrite, and it will cause formation damage that will reduce the well injectivity. Stimulation treatments are required to recover the well injectivity; this requires stopping water injection to perform the stimulation treatments, and also it requires flowing back the well after stimulation treatment. In this study, we are proposing a new method that we can use to stimulate water injectors without stopping the water injection. The new method includes adding a chelating agent to the injected seawater at the wellhead at 15 wt% concentration. The fluid will be injected at the surface with the seawater with a specific dose to achieve the required concentration. Several solubility and coreflooding tests were performed with actual carbonate cores and GLDA (glutamic-di acetic acid) chelating agent at different temperatures. The chemical injection does not need coiled tubing and can be injected at the surface with the seawater. The chelating agents will sequester all calcium in solution and will prevent the calcium sulfate precipitation. GLDA chelating agent will be used with seawater, with no need to use treated or fresh water. Also, flowing back the well is not required because the fate of GLDA in the aquifer is soluble. Solubility tests up to 250°F at high pressure showed that the GLDA is stable with seawater. Coreflood experiments and computed-tomography scans showed the ability of GLDA in the creation of dominant wormholes through 6- and 1.5-in. carbonate cores at 212 and 150°F, respectively. GLDA chelating agent can be used to stimulate seawater injectors without additives because this chemical is stable and mild with the well tubulars. Previous corrosion studies on GLDA showed that its corrosion rate is in the allowable range without adding corrosion inhibitors.

Corrosion analysis and inhibition studies in the process of natural gas wet desulfurization

The present work investigates the corrosion on Fe–Al alloy steel in the process of the wet desulfurizing of Sichuan natural gas purification master plant. The morphology and composition of the corrosion scale are characterized by scanning electron microscopy, X-ray power diffraction and energy-dispersive spectroscopy. Results show that corrosion scale mainly consists of FeS. Electrochemical methods such as polarization curve and electrochemical impedance spectroscopy were used to analyze the effects of alcohol amine concentration and temperature on the corrosion. It can be found that the strongest corrosion occurs at the temperature of 50°C and the concentration of 40% alcoholic solution. In addition, the electrochemical experiments demonstrate that the corrosion rate can be apparently reduced by adding corrosion inhibitors such as diethanol amine and triethanolamine.

Review of Copper Atmospheric Corrosion in H<sub>2</sub>S

The losses due to copper corrosion in H2S atmospheric corrosion have attracted much focus. It’s important to improve copper corrosion resistance that the corrosion law, corrosion mechanism and characteristics were studied in H2S environment. This paper reviewed the corrosion behavior of copper, analyzed the impact of environment factors and corrosion analysis tools. Through evaluating and improving corrosion by external factors, including improving corrosive environment, using coating protection and adding corrosion inhibitors, appropriate corrosion measures were taken to extend the life of the equipment.

Performance Evaluation of the Carbon Dioxide Corrosion Inhibitor IMC-1

The carbon dioxide corrosion inhibitor IMC-1 was composed by caprylic acid amide polyoxyethylene ethers (n=4-5) and a small amount of the TX-10(5%). When the concentration was 200 mg/L, N80 steel corrosion rate was less than 0.125mm/a. With the CO2partial pressure and temperature increased, N80 steel corrosion rate was decreased. From the electrochemical polarization curve, the adding corrosion inhibitor prevented the electrode reaction. The corrosion inhibitor IMC-1 was anodic inhibitor.

The influence of adding corrosion inhibitor and pH on the electrochemical properties of hybrid films applied to galvanised steel

This study was aimed at coating galvanised steel with a hybrid film obtained from a sol consisting of silane precursors 3 - (trimetoxisililpropil) methacrylate (TMSPMA) and tetraethoxysilane (TEOS). The pH of the hydrolysed-silane solution was 1 and 3. The influence of adding corrosion inhibitor (i.e. 0.01M cerium nitrate) was evaluated for all samples. The hybrid films were deposited by dip-coating. The film was characterised scanning electron microscopy (SEM), profilometry, contact angle measurement, potentiodynamic polarisation and electrochemical impedance spectroscopy. The results showed that solution pH influenced hybrid film formation and final surface properties. Additionally, cerium nitrate as corrosion inhibitor addition enhances corrosion resistance of the films.

Improvement of the Serviceability of Damaged Concrete and Reinforced-Concrete Structures by Sealing Hardening Injections

We consider main approaches to the analysis of the engineering state of concrete and reinforced-concrete structures with in-service defects and evaluate the efficiency of improvement of their serviceability by injection technologies. We compute the parameters of these technologies and propose numerous injection composite materials with high technological characteristics based on polyurethane and polyepoxide. The efficiency of these materials is confirmed by the results of testing of laboratory specimens with filled stress concentrators. Additional possibilities of corrosion protection of uncoated steel reinforcement by adding corrosion inhibitors to the injection compositions are discovered and the technological features of hardening of damaged structures by filling detected defects are revealed.

Investigation on Protectional Ability on Steel Bar of Compound Corrosion Inhibitor Applied in Seawater-and-Sea Sand Concrete

Seawater and sea sand mixed in concrete will cause rebar of structural concrete corrosion, referring to the principles of composition and design of MCI and Pearson’s Hard-Soft Acid-Base (HSAB) theory, as well as to synergy effect of corrosion inhibitor applied in chemical industry, compound corrosion inhibitor has been designed consisting of diisopropanolamine, surface active agent, inorganic salts and so on. This paper research the relation between polarization potential and time of rebar in seawater-and-sea sand concrete through a series of experiments by adding corrosion inhibitor into seawater-and-sea sand concrete to improve its corrosive resistance characteristics. The results indicate that Z5 has the best inhibition effect. Corrosion inhibitor Z5 comprises 50% of triethanolamine, 20% of dimethylethanolamine (DMEA), 25% of triethoxysilane and 5%lithium nitrate, and its proper content applied in seawater-and-sea sand concrete is 1.5%. Rebar have been embedded in seawater-and-sea sand concrete for the long-term test. The results show that corrosion resistance performance of seawater-and-sea sand concrete with corrosion inhibitor Z5 was significantly improved, and the embedded bar was not corroded at all within 420 days.

On-line monitoring and quantitative analysis of biofouling in low-velocity cooling water system

To monitor and analyze the biofouling phenomenon caused primarily by microbial suspended solids (MSS), a ‘biofouling tube’ apparatus consisting of a carbon steel tube, a differential pressure transmitter, a corrator, and a cooling water circulation device was designed and fabricated. By measuring continuously the pressure drop across the biofouling tube and using the correlation between the fluid’s friction factor and surface roughness, we quantitatively analyzed the influence of MSS concentration, temperature, and fluid velocity on the rate of biofilm growth on the metal surface. The result indicated that the fluid velocity had the most profound impact, e.g., lowering the linear velocity from 0.3 to 0.15 m/sec resulted in about a four times higher biofouling rate. Up to 50 ppm MSS, the biofouling rate was proportional to the MSS concentration. The biofouling rate at 35°C was about 1.75 times higher than that of 45°C., probably due to the diminishing effect of thermolabile microorganisms exposed at 45°C. It was also demonstrated that the biofouling could be significantly reduced by incorporating cooling water treatment programs such as protective pre-filming and adding corrosion inhibitors. This apparatus, if installed on-site at a sidestream of a cooling water system, could be used to monitor the biofouling tendency on-line and to suggest timely preventive maintenance actions.

Self-assembled monolayers of alkanethiols on copper provide corrosion resistance in aqueous environments

Alkanethiols adsorb onto copper surfaces and form densely packed monolayer films that inhibit corrosion of the underlying copper substrate. The performance of these self-assembled monolayers are insensitive to the presence of water as they provide equal levels of protection in both dry and humid oxygen-containing atmospheres. This observation suggests that the monolayer films provide a barrier against water penetration, as the corrosion of untreated copper samples is much more rapid in the presence of water. In these applications, longer-chained adsorbates — C 18H 37SH and C 22H 45SH — provided the greatest levels of protection. Monolayers formed from these adsorbates were also effective as barrier layers toward oxidation when the samples were immersed in oxygen-saturated water for over 1 week. These densely packed, chemisorbed layers maintained their level of performance during the weeklong exposure without the need for adding corrosion inhibitor molecules to the contacting water phase. Preliminary experiments show that bilayer assemblies formed from the sequential adsorption of HS(CH 2) 22OH and CH 3(CH 2) 17SiCl 3 provide a stable molecular architecture for forming thicker, robust coatings on the copper surface; however, the use of chlorine-containing reagents in the formation of this assembly results in defects that seriously impede the inhibition properties of the layers.

Protective properties of motor oils and oil corrosion inhibitors

Investigates the protective properties of USSR and foreign motor oils in comparison with the protective properties of preservative and operational/preservative oils that are used in engines, and the effects on these oils from adding corrosion inhibitors. Shows that in order to formulate operational/preservative motor oils with a high level of protective properties, it is necessary to develop corrosion inhibitors with better protective properties than are given by the AKOR-1, KP, or MSDA-1. Finds that to ensure that the oils will have a high level of service properties, the corrosion inhibitors must meet the following requirements: they must be ashless or low-ash and must be compatible with the functional additives; they must be adequate in thermal stability (at the level of the functional additives for motor oils) and in physical stability; they must not have any adverse effects, or only very minor effects, on the basic service properties of motor oils, such as detergency, oxidation resistance, bearing corrosion, lubricity, and antiwear properties.