Effect of kolsterising treatment on surface properties of a duplex stainless steel

In recent years, attempts of engineering the surface of duplex stainless steels were made in order to enhance their hardness and tribological properties, without affecting their corrosion resistance. A possibility of improving these properties is provided by a family of processes developed by Prof. B.H. Kolster in the Netherlands in the late 1980’s. These processes (usually referred to as Kolsterising® treatments) consist in a low temperature surface carburizing, which involves the diffusion of large quantities of carbon atoms (up to 6-7 wt.%) into the steel at a diffusion temperature below 450 °C. In the present paper a characterization of the surface layer of Kolsterised duplex SAF 2205 stainless steel was carried out to study the effects of this treatment on surface properties. The characterization includes optical metallographic examination, microhardness tests and SEM-EDS investigation on the Kolsterised steel in the as treated condition and after annealing treatments at 200, 250, 300 350 and 400°C for 10 hours, to evaluate the stability of Kolsterised layer’s properties with a moderate increase in temperature. Moreover, complying with ASTM G48-03 Method E Standard, in order to evaluate the effect of the Kolsterising® treatment on steel pitting resistance, the critical pitting temperature was obtained for Kolsterised duplex SAF 2205 stainless steel compared with the base metal

Click-based porous cationic polymers for enhanced carbon dioxide capture

Imidazolium based porous cationic polymers were synthesized using an innovative and facile approach, which takes advantage of the Debus Radziszewski reaction to obtain meso- and microporous polymers following click chemistry principles. In the obtained set of materials, click based porous cationic polymers have the same cationic backbone, whereas they bear the commonly used anions of imidazolium poly(ionic liquid)s. These materials show hierarchical porosity and a good specific surface area. Furthermore, their chemical structure was extensively characterized using ATR FTIR and SS NMR spectroscopies, and HR MS. These polymers show good performance towards carbon dioxide sorption, especially those possessing the acetate anion. This polymer has an uptake of 2 mmol per g of CO2 at 1 bar and 273 K, a value which is among the highest recorded for imidazolium poly(ionic liquid)s. These polymers were also modified in order to introduce N-heterocyclic carbenes along the backbone. Carbon dioxide loading in the carbene-containing polymer is in the same range as that of the non-modified versions, but the nature of the interaction is substantially different. The combined use of in situ FTIR spectroscopy and microcalorimetry evidenced a chemisorption phenomenon that brings about the formation of an imidazolium carboxylate zwitterion.Comment: 29 page, 33 figure

Adsorption Properties of Ce5(BDC)7.5(DMF)4 MOF

In this article we report on the spectroscopic and adsorptive studies done on Ce(III)-based MOF possessing, upon desolvation, open metal sites, and a discrete surface area. The Ce-based MOF was synthesized from terephthalic acid linker (H2BDC) and Ce3+ cations by the classical solvothermal method. Preliminary powder X-ray diffraction analysis showed that the obtained materials corresponded to the ones reported by other authors. Spectroscopic techniques, such as XAS and in situ FTIR with probe molecules were used. In situ FTIR spectroscopy confirmed the successful removal of DMF molecules within the pore system at temperatures above 250 \ub0C. Moreover, the use of CO as a probe molecule evidenced the presence of a Ce3+ open metal sites. Detailed volumetric and calorimetric CO2 adsorption studies are also reported

Effect of Kolsterising treatment on surface properties of a duplex stainless steel

In recent years, attempts of engineering the surface of duplex stainless steels were made in order to enhancetheir hardness and tribological properties, without affecting their corrosion resistance. A possibility ofimproving these properties is provided by a family of processes developed by Prof. B.H. Kolster in theNetherlands in the late 1980’s. These processes (usually referred to as Kolsterising® treatments) consist in a lowtemperature surface carburizing, which involves the diffusion of large quantities of carbon atoms (up to 6-7wt.%) into the steel at a diffusion temperature below 450 °C. In the present paper a characterization of thesurface layer of Kolsterised duplex SAF 2205 stainless steel was carried out to study the effects of this treatmenton surface properties. The characterization includes optical metallographic examination, microhardness testsand SEM-EDS investigation on the Kolsterised steel in the as treated condition and after annealing treatments at200, 250, 300, 350 and 400°C for 10 hours, to evaluate the stability of Kolsterised layer’s properties with amoderate increase in temperature. Moreover, complying with ASTM G48-03 Method E Standard, in order toevaluate the effect of the Kolsterising® treatment on steel pitting resistance, the critical pitting temperature wasobtained for Kolsterised duplex SAF 2205 stainless steel compared with the base metal