The friction surfacing process of two deposited layers on two deposition surface conditions, i.e., a smooth interface and a rough interface, was investigated. The control parameter of the deposition process was the rod feed rate with the use of a conventional milling machine. Analyzes of the surface characterization and microstructural characterization along the produced deposits were performed. The interface strength of the substrate/deposit1 (smooth) and deposit1/deposit2 (rough) was evaluated by bending tests and the micro-hardness profile along the transverse section of the substrate/deposit1 and deposit1/deposit2. The bending tests revealed the presence of smalls delaminations with no evidence of fracture at the rough deposit1/deposit2 interface (D1/D2) with less predominance in the deposition condition 3B. This suggests that the combination of the travel speed of 5.5 mm/s and an increase in the consumable rod feed rate of (≥5.5 mm/s) increases the adhesive strength of the two produced interfaces.
This work compares different electrodeposition procedures to produce nickel black coatings as greener and less toxic alternatives to Cr(VI)-based coatings used in different applications. Nickel and nickel-plated brass served as substrates in studies with a Hull cell and polarization curves. After a set of comparative experiments, the best electrodeposition procedure was further studied and optimized. Optimal conditions were found with a bath consisting of 75 g/L NiCl2·6H2O + 30 g/L NaCl and a current density of 0.143 A dm−2 applied for 5 min at room temperature. Furthermore, a pre-treatment with 18.5 vol.% of hydrochloric acid in water was found to be necessary to warrant good coating adhesion to the substrate. The black color is attributed to the development of a nanostructured surface that absorbs the incident light. Corrosion testing was performed in 0.5 M NaCl aqueous solution using electrochemical impedance spectroscopy (EIS) and polarization tests.
The aim of this work was to produce deposits of AA6351-T6, reinforced with alumina (Al 2 O 3 ) particles, over a substrate of AA5052-H32 through friction surfacing. AA6351-T6 consumable rods were drilled with one and two holes, which were filled with Al 2 O 3 particles posteriorly. To perform the deposition, a conventional KONE KFE-3/BR milling machine was used. The results showed that Al 2 O 3 particles increase the hardness values of the produced deposits when compared to those without particle addition. The coatings presented a fine equiaxed grain size distribution, once the grain refinement was nearly 48% lower than the as-received material. Moreover, deposit regions that showed finer grain boundaries also showed a higher volume fraction, which can be related to the particle stimulated phenomenon. Electron backscatter diffraction results showed the occurrence of low angle grain boundary substructures and lattice rotation, indicating that the material undergoes dynamic recrystallization during friction surfacing.
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