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Heat treatment is often employed to control the mechanical properties of selective laser melted (SLMed) AlSi10Mg, which also alters its microstructure and corrosion resistance. Therefore, a SLMed AlSi10Mg alloy was heat treated at 300 °C and 400 °C for 2 h to investigate its microstructural evolution and corrosion behavior. Abnormal corrosion behavior is observed in the sample heat treated at 300 °C. Heat treatment destroys the cellular Si network in the microstructure of the SLMed AlSi10Mg sample and promotes the formation of extremely fine Si particles; in contrast, such a microstructure cannot form a protective film on the surface of the sample, which leads to rapid corrosion along the cracked Si network inward to the inner Al matrix without the microgalvanic effect. • AlSi10Mg alloy is produced by selective laser melting (SLM) and then heat treated. • SLM-produced AlSi10Mg alloy exhibits a continuous network of Si particles. • The intact Si network ruptures up to uniformly distributed Si particles. • Corrosion resistance of SLM-produced AlSi10Mg is dependent on the morphology. [ABSTRACT FROM AUTHOR]

Electrochemical measurements and microstructural studies were carried out to investigate the corrosion behaviour of the different planes for the Al-12Si alloy produced by selective laser melting (SLM). The electrochemical results demonstrate that the building direction plane (XZ-plane) of the SLM-produced alloy exhibits better corrosion resistance in comparison with the building plane (XY-plane) in 3.5 wt% NaCl solution. The relatively inferior corrosion resistance of the XY-plane is ascribed to that the grown corrosion products extrude the deep and small-bore Si shells on the aluminum substrate, thereby causing the crack of Si shells. Without such a cover of the Si shells, the Cl − would continuously penetrate into the aluminum substrate and ultimately induce occurrence of the severe pitting. As for the XZ-plane, the corrosion products cannot grow and deposit in its shallow and large-bore Si shells, instead of transferring to the testing solution. The undamaged Si shells and formed oxide film constitute a protective layer to protect the aluminum substrate from the attack of Cl − , thereby displaying superior corrosion behaviour for the XZ-plane. [ABSTRACT FROM AUTHOR]

A facile strategy to boost anticorrosion potency of graphene oxide/silica hybrid sol-gel coating is developed through fully exploiting the capabilities of graphene oxide (GO). Together with a barrier to corrosives and crack inhibitor, GO was further explored herein as a regulator to regulate the gelation process and provide robust coating films with stratified microstructures and ultimately extended diffusion paths. The sol-gel coating with stratified microstructure achieved on AA5052 aluminum alloy surface afforded greatly enhanced corrosion protection capability as assessed by electrochemical measurements and immersion tests. The corrosion current density of the sample of a hybrid GO sol-gel film was about 30 times less than that of sample of pure sol-gel film sample. The regulation mechanism of GO during the film formation process and the anticorrosive protection properties of the film were discussed. [ABSTRACT FROM AUTHOR]

The corrosion of steel exposed under a direct current (DC) electric field during simulated wet-dry cycles was investigated using weight gain, electrochemical tests, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results show that the steel exposed to a DC electric field exhibits a higher corrosion rate than those exposed under no DC electric field. The higher the DC electric field intensity, the higher the corrosion rate of steel. The XRD and SEM analyses indicate that more γ-FeOOH and cracks appear in the rust formed on steel exposed to the DC electric field. The porous γ-FeOOH, formation and expansion of cracks enhance the transfer of oxygen and corrosion products, thereby accelerating corrosion of steel exposed to DC electric field. [ABSTRACT FROM AUTHOR]

Electrochemical measurements and microstructural analysis were performed to study the corrosion resistance of different planes of Ti-6Al-4V alloy manufactured by selective laser melting (SLM). The electrochemical results suggest that its XY-plane possesses a better corrosion resistance compared to XZ-plane in 1 M HCl solution, in spite of slight difference in 3.5 wt.% NaCl solution, suggesting that the different planes exhibit more pronounced distinction in corrosion resistance in harsher solution system. The inferior corrosion resistance of XZ-plane is attributed to the presence of more α′ martensite and less β-Ti phase in microstructure for XZ-plane than for XY-plane of the SLM-produced Ti-6Al-4V alloy. [ABSTRACT FROM AUTHOR]