RESUMO
Friction surfacing (FS) is a solid-state coating technology for metallic materials, where the deposition of a consumable material on a substrate is enabled via friction and plastic deformation. The deposited layer material commonly presents a significantly refined microstructure, where corrosion could be an issue due to this grain refinement within the layer deposited, possibly creating micro galvanic pairs. The present work investigates the corrosion behavior of the FS deposited material as well as stud base material and substrate using cyclic polarization tests and open circuit potential (OCP) monitoring. Comparing the FS deposited material and the respective consumable stud base material (both AA5083), the grain size is correlated with the results from the corrosion tests, where the deposited material shows more equiaxed and refined grains in comparison to the stud base material. The cyclic potentiostatic polarization tests showed that the stud base material is more resistant to pitting nucleation presenting smaller pits and a lower amount of pits compared to deposited material and substrate. As a complement to OCP test, the stud base material is also more stable on a chloride solution compared to the substrate and the deposited material.
RESUMO
The COVID-19 pandemic has caused an overload on the health care system on a global scale. Because the disease affects the respiratory system, patients may require ventilator equipment for breathing, and consequently, numerous tracheal intubations have been performed. The video laryngoscope is a medical device that aids this procedure. It is used by anesthesiologists to visualize the anatomical structures of the larynx during tube insertion. Unfortunately, many hospitals worldwide are unable to afford sufficient units of this medical device. To satisfy the high demand, low-cost alternatives employing three-dimensional (3D) printing techniques have been developed for health care professional's use. With the intention of ensuring the efficiency, reproducibility, and security of the 3D-printed laryngoscope, this article presents a novel model with versions for pediatric and adult use, which was developed under the supervision of a medical team. The mechanical performance of 3D-printed prototypes (of the proposed models) was evaluated using mechanical assays, and the results indicated a satisfactory safety factor.
RESUMO
In this work, friction-stir welding (FSW) was employed to alloy 625 grade I (soft annealed) sheets. Therefore, solid-state based welding was undertaken with a tool rotational speed of 200 rpm and a welding speed of 1 mm/s. Microstructural features were analyzed by light optical and scanning electron microscopy (LOM and SEM). Moreover, microhardness measurements were performed. The susceptibility to intergranular corrosion was verified by the double-loop electrochemical potentiokinetic reactivation (DL-EPR) test. Complementary, intergranular corrosion was also evaluated by the ASTM G28 Method A. FSW promoted grain refinement, increased microhardness, and reduction in the degree of sensitization. Finally, the mean corrosion rate observed in the ASTM G28 Method A test was 0.4406 mm/year, which suggests a good weld quality.