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Article Citation - WoS: 23Citation - Scopus: 27Effect of Electrodeposition Parameters on the Current Density of Hydrogen Evolution Reaction in Ni and Ni-mos2 Composite Coatings(Esg, 2013) Gueler, E. Saraloglu; Konca, E.; Karakaya, I.; Saralog̀lu Güler, E.; Metallurgical and Materials EngineeringNickel composites with co-deposited insoluble, solid lubricant particles such as MoS2 have been reported to reduce friction. It is known that hydrogen evolution reaction (HER), competes with nickel deposition. The influence of the parameters and their interaction effects on the peak current density of HER during the electrodeposition of Ni and Ni-MoS2 composite coatings were studied by fractional factorial design. The parameters and their ranges studied were; MoS2 particle concentration (0-30 g/l), temperature (30-50 degrees C), pH (2-4) and two surfactants, namely; ammoniumlignosulfonate (ALS) and depramin-C (DC) (0-1 g/l). Electrodeposition processes were carried out from a typical Watts bath containing leveler, wetting agent and brightener by using a potentiostat. The peak current densities (i(p)) were extended to higher values and the peaks on linear sweep voltammograms became noticeable by increasing the scan rate from 20 mV/s to 100 mV/s over the range of 0 to 2.5 V. The peak current densities (i(p)) of HER for each experimental route were determined by fractional factorial design for two mineral processing surfactants; ammoniumlignosulfonate (ALS) and depramin-C (DC) using a statistical analysis software named Minitab [1]. Adding MoS2, decreasing temperature and increasing pH had decreasing effects on the peak current density of HER regardless of the surfactant used. On the other hand, the surfactants increased the peak current density.Article Production of 20 Mm Thick Api Psl 2 X60 and X70 Grade Plates From a Nb-Ti Microalloyed Steel(2020) Konca, ErkanThis study was undertaken to determine the controlled rolling and cooling conditions for the production of 20 mm thick American Petroleum Institute (API) X60 and X70 grade steel plates. Nb-Ti microalloyed steel slabs of 200 mm thickness were rolled at fourdifferent finish rolling temperatures (conventional, 950°C, 850°C and 800°C). In some trials, a water table was employed to provide accelerated cooling just after finish rolling. Mechanical tests (tensile, impact and drop weight tear-DWTT) and microstructural examinations were performed on the samples taken from the trial production plates. Fine grainedand essentially ferritic microstructures with strength values satisfying the minimum yieldstrength requirement of 415 MPa for the API X60 grade were easily obtained in all rollingconditions. However, the minimum yield strength requirement of 485 MPa for the APIX70 grade was reached only when accelerated cooling was applied after finish rolling. Theminimum 85% shear fracture required by the DWTT of the API PSL 2 specification couldbe met when the finish rolling temperature was lowered or when accelerated cooling wasapplied regardless of the finish rolling temperature.
