Kazem Sabet-Bokati

This study presents a novel approach to evaluate the galvanic corrosion risk of mild steel coated with graphene-embedded epoxy coatings. The potential for graphene platelets to promote anodic dissolution of the underlying steel substrate via galvanic corrosion mechanisms was systematically assessed through the accelerated alternating current-direct current-alternating current (AC-DC-AC) technique and cathodic disbondment testing. The possible risk of displacing cathodic reactions from the coating–steel interface to the dispersed graphene platelets within the epoxy matrix was investigated by evaluating the degradation trend of the graphene-containing coating under the AC-DC-AC test. The degradation behaviour of both pure epoxy and graphene-embedded epoxy coatings during accelerated aging was characterized using electrochemical impedance spectroscopy (EIS) measurements. The finding highlighted the negligible catalytic effect of incorporated graphene platelets on the anodic dissolution of steel substrate. On the other hand, as an inert filler, graphene platelets contributed to the enhancement of the structural integrity of the epoxy matrix during the AC-DC-AC test and natural immersion in NaCl 3.5 wt % solution by enhancing the barrier performance of the coating. Despite their spectacular barrier performance, damaged graphene-containing coatings performed inferiorly against corrosion-induced delamination compared to pure epoxy. Samples underwent the cathodic disbondment test to eliminate the effect of substrate anodic dissolution from corrosion-induced delamination. The accelerated delamination of graphene-embedded epoxy coatings was attributed to the destructive impact of graphene platelets on the interfacial adhesion of the epoxy matrix to the steel substrate.

Copper-based materials have long been used for their outstanding thermal and electrical conductivities in various applications, such as heat exchangers, induction heat coils, cooling channels, radiators, and electronic connectors. The development of advanced copper alloys has broadened their utilization to include structural applications in harsh service conditions found in industries like oil and gas, marine, power plants, and water treatment, where good corrosion resistance and a combination of high strength, wear, and fatigue tolerance are critical. These advanced multi-component structures often have complex designs and intricate geometries, requiring extensive metallurgical processing routes and the joining of the individual components into a final structure. Additive manufacturing (AM) has revolutionized the way complex structures are designed and manufactured. It has reduced the processing steps, assemblies, and tooling while also eliminating the need for joining processes. However, the high thermal conductivity of copper and its high reflectivity to near-infrared radiation present challenges in the production of copper alloys using fusion-based AM processes, especially with Yb-fiber laser-based techniques. To overcome these difficulties, various solutions have been proposed, such as the use of high-power, low-wavelength laser sources, preheating the build chamber, employing low thermal conductivity building platforms, and adding alloying elements or composite particles to the feedstock material. This article systematically reviews different aspects of AM processing of common industrial copper alloys and composites, including copper-chrome, copper-nickel, tin-bronze, nickel-aluminum bronze, copper-carbon composites, copper-ceramic composites, and copper-metal composites. It focuses on the state-of-the-art AM techniques employed for processing different copper-based materials and the associated technological and metallurgical challenges, optimized processing variables, the impact of post-printing heat treatments, the resulting microstructural features, physical properties, mechanical performance, and corrosion response of the AM-fabricated parts. Where applicable, a comprehensive comparison of the results with those of their conventionally fabricated counterparts is provided.