Mitigating CO2 Corrosion of Natural Gas Steel Pipelines by Thermal Spray Aluminum Coatings

Internal pipeline corrosion due to CO2 is a major challenge facing the oil and gas industry. To protect the pipelines and equipment from the ravages of CO2 corrosion, novel sacrificial coatings can be used. The objective of this study was to investigate the corrosion behavior of Al-based alloys as sacrificial coatings to protect pipelines in a CO2-saturated aqueous electrolyte (3.5 wt.% NaCl) at 4 bar CO2 partial pressure (3 barg) and 40 oC. The corrosion resistance of Al-based alloys and thermal spray coatings was evaluated in an electrochemical reaction autoclave using electrochemical methods (potentiodynamic polarization, linear polarization resistance, and electrochemical impedance spectroscopy). Post-corrosion surface characterization was performed by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy. The obtained data show Al-based alloys demonstrated promising protection against CO2 corrosion with no breakaway degradation issues.

A Study of the Possibility of Obtaining Deposited Coatings based on Intermetallic Titanium and Aluminum Compounds using the Chemical Vapor Transport Method

Theoretical and experimental investigations of processes of titanium-aluminum coating formation on refractory wire substrates by the Chemical Vapor Transport Reactions (CVT) method were carried out. Modelling of CVT was based on the thermodynamic analysis of an equilibrium iodide system implying the presence of one of titanium aluminides in the condensed phase, titanium and aluminum iodides in the gas phase, as well as atomic and molecular iodine. The fact that the volatility and stability of various metals are strongly interrelated was considered as a working hypothesis, which made it possible to obtain a number of alloys with the simultaneous decomposition of metal iodides constituting an alloy. Experiments on the deposition of titanium-aluminum coatings were conducted in a quasi-closed reactor, which allowed us to obtain deposited coatings on long-length refractory substrates

Fabrication of Porous Aluminum Coating by Cored Wire Arc Spray for Anchoring Antifouling Hydrogel Layer

Biofouling has been persisting as a worldwide problem due to the difficulties in finding efficient environment-friendly antifouling coatings for long-term applications. Developing novel coatings with desired antifouling properties has been one of the research goals for surface coating community. Recently hydrogel coating was proposed to serve as antifouling layer, for it offers the advantages of the ease of incorporating green biocides, and resisting attachment of microorganisms by its soft surface. Yet poor adhesion of the hydrogel on steel surfaces is a big concern. In this study, porous matrix aluminum coatings were fabricated by cored wire arc spray, and the sizes of the pores in the aluminum (Al) coatings were controlled by altering the size of the cored powder of sodium chloride. Silicone hydrogel was further deposited on the porous coating. The hydrogel penetrated into the open pores of the porous Al coatings, and the porous Al structure significantly enhanced the adhesion of the hydrogel. In addition, hydrogel coating exhibited very encouraging antifouling properties.

Investigation of the Protection Performance of Mg and Al Coated Copper in High Temperature or Marine Environments

Copper is commonly used in many applications such as electric wires, industrial machinery, boat propellers and heat exchangers. Although Cu is resistant to corrosion in ambient conditions, it is highly susceptible when exposed to harsh environments such as high-temperature air or marine atmospheres. The application of magnesium or aluminum coatings on Cu can efficiently smooth this disadvantage without affecting its primer properties. In the herein investigation, the deposition of these coatings was accomplished by pack cementation, a simple electrochemical technique which can be easily incorporated in the industrial scale. The final coatings were tested under high temperature environments by non-isothermal (dynamic) and isothermal thermogravimetric measurements, and in artificial sea water (3.5 wt.%-NaCl) by electrochemical corrosion. The structure of both coatings was compact with elevated thickness. The oxidation and corrosion measurements revealed that the coated samples had much better performance compared to the uncoated copper coupons. Furthermore, Al coatings were found to have the best performance when exposed in high temperature environment.

Properties of Flame Spraying Coatings Reinforced with Particles of Carbon Nanotubes

The article presents the results of the preliminary research of tribological properties of flame sprayed nickel and aluminum coatings reinforced with carbon nanotubes made on the structural steel S235J0 substrate. The carbon material – carbon nanotubes Nanocyl NC 7000 (0.5 wt.% and 1 wt.%) was used for structural reinforcement. The properties evaluation was made by the use of optical microscopy, scanning electron microscopy, Raman spectroscopy, microhardness measurements, and by means of abrasion and erosion resistance laboratory tests. The obtained results were compared with pure nickel powder coatings 2N5 (Ni 99.5%) and with pure aluminum powder coatings (EN AW 1000 series). It was proved that the flame spraying of nickel and aluminum coatings reinforced with particles carbonaceous material can be an effective alternative for other more advanced surfacing technology. The preliminary test results will be successively extended by further experiments to contribute in the near future to develop innovative technologies, that can be implemented in the aviation industry and the automotive. The presented research is a continuation of the work previously published.