Prior studies found that the carburization tendency is negligible for technically developed materials at temperatures below 900 °C, especially for Al-containing alloys compared to non-Al-containing alloys applied in steam cracking reactors. However, it is unclear whether this benefit remains at higher temperatures. This work compared coke deposition tendencies of recently developed alloys to each other and to a conventional material when cracking ethane at a higher temperature (950 °C) than previously reported. Under the studied experimental conditions, coking rates vary in the range of 1.22 × 10 −6 to 20.5 × 10 −6 kg/(m 2 • s) for Al-containing alloys, while for non-Al-containing alloys, coke deposition rates fall in a range of 4.95 × 10 −6 to 33 × 10 −6 kg/ (m 2 •s). In general, aluminum-containing alloys showed less coke formation and improved stability against aging after five cracking cycles compared to the non-aluminum-containing materials. The results also showed that substantially less, if any, carburization could be detected in developed alloys even at high temperatures, in contrast to the results from a reference conventional alloy of 27/ 34 Cr−Ni. At higher temperatures, the protective oxide surface layer of the Al-containing alloys remained noticeably durable and integrated with negligible spallation compared to the ones of non-Al-containing alloys. In fact, the 27/34 Cr−Ni alloy showed the highest coking rate and carburization, implying the most vulnerable oxide surface layer relative to the other alloys. However, energydispersive X-ray (EDX) results showed no signs of carburization or deterioration of the surface of 27/34 Cr−Ni after experiments at 880 °C, indicating that both the temperature and matrix composition can play significant roles in determining the suitability of an alloy for application in steam crackers.
Implant design and functionalization are under significant investigation for their ability to enhance bone-implant grafting and, thus, to provide mechanical stability for the device during the healing process. In this area, biomimetic functionalizing polymers like dopamine have been proven to be able to improve the biocompatibility of the material. In this work, the dip coating of dopamine on the surface of the magnesium alloy AZ31 is investigated to determine the effects of oxygen on the functionalization of the material. Two different conditions are applied during the dip coating process: (1) The absence of oxygen in the solution and (2) continuous oxygenation of the solution. Energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) are used to analyze the composition of the formed layers, and the deposition rate on the substrate is determined by molecular dynamic simulation. Electrochemical analysis and cell cultivation are performed to determine the corrosion resistance and cell’s behavior, respectively. The high oxygen concentration in the dopamine solution promotes a homogeneous and smooth coating with a drastic increase of the deposition rate. Also, the addition of oxygen into the dip coating process increases the corrosion resistance of the material.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.