Tribological and corrosion performance of electrodeposited Ni-Fe/Al2O3 coating

Nickel–Iron coating was formed from a sulfate base electroplating bath under a current density of 3 A/dm 2 and turbulence of 300 rpm on a previously prepared cylindrical steel substrate. In order to obtain a sample including nickel composite coating, different amounts of alumina particle powder were added to the plating solution of the sample in question. By adding different quantities of ferrous sulfate to the electroplating bath under a current density of 2.5 A/dm 2 and turbulence of 300 rpm, an optimal sample containing 20 g/L of ferrous sulfate was obtained was free of any stress and microcracks. A hardness test was performed for the optimal sample among the nickel–iron¿ composite samples, and the sample containing 50 g/L of alumina particles was selected as the optimal sample. The Ni–Fe/Al 2O3 composite sample was tested for hardness, corrosion and wear. The obtained results showed that the highest hardness level is equivalent to 740 HV and the best corrosion resistance with the most positive corrosion potential. The lowest amount of wear mass is equal to 0.1 mg, and it showed the highest wear resistance.Peer ReviewedPostprint (published version

Comparison between structural configurations designed by steel shear wall, moment resistant frame and X shape bracing systems

Nowadays, in order to increase construction of tall structures, the importance of choosing optimum systems, with a huge energy absorption capacity against wind and earthquake loads, has been widely considered. Since four decades ago, steel shear walls had been used as a stiff and high performance lateral system. This study is about the effect of concrete filled steel tubes (CFT) columns as vertical boundary elements of steel shear wall on seismic behavior of steel structures. Due to do this, three 10- storey steel structures, with similar plans and lateral load career systems of steel shear wall, coinciding X-bracing, and moderate steel frame were analyzed by means of non-linear, time-history method through SAP2000 software, and the results of roof displacement of them were compared with each other. Also after validating a two-storey, single-span frame sample with steel shear walls and CFT columns, 3 single-storey structures were analyzed by means of hysteresis and pushover, through ABAQUS software. The results of this study showed that a shear wall system presents suitable stiffness, resistance and ductility in comparison with other lateral bearing systems.Peer ReviewedPostprint (published version

A new theoretical model for surface roughness prediction in rotational abrasive finishing process

Rotational abrasive finishing (RAF) is a new nano-finishing technique in which the finishing forces are applied to the workpiece by the opposite rotations of a stirring-blades and the workpiece. The RAF process allows for finishing the inner and outer surfaces of workpieces, particularly complex ones with axial symmetry. The present study aims to propose a new theoretical model to obtain deeper insights into the material removal mechanism, surface roughness prediction, and forces in RAF process. Since the abrasive-workpiece interaction is random and complex in nature in the RAF, some initial assumptions were considered. To validate the repeatability of the experimental results, the experiments were designed based on the Response surface method (RSM). To validate the new proposed theoretical model, a number of influential parameters were investigated. It was found that the stirring-blade speed (S), working gap (W), and abrasive grain size (A) had significant effects on Ra. The minimum surface roughness (Ra) was obtained to be 46.87 nm at a rotational speed of 600 rpm, a working gap of 1 mm, and grain size of 18 µm. The experimental results were relatively in good agreement with the theoretical results so that the maximum error was about 24%. This can be assumed that the most important explanation for the difference between the theoretical and experimental results can be attributed to the initial theoretical assumptions.Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (published version