RESUMO
To enhance the products fabricated from wire arc additive manufacturing (WAAM) processes, it is very important to implement a critical assessment of the corrosion performance of additively manufactured stainless steel (SS) for the application of additive manufacturing parts widely used in industries. The common defects in metal additive manufacturing, which include porosity, poor surface finish, oxidation, environmental factor, residual stress, and microstructural defects, are known to significantly influence the corrosion behavior of WAAM-processed SS components prepared to be used under different corrosive and marine environments. This article reviews the recently published works on WAAM-processed SS and provides a critical overview method to improve the corrosion performance of SS components built with the WAAM processes. It also documents some significant factors that determine the corrosion resistance of WAAM-processed SS and identifies key areas for future work.
RESUMO
The current research trend for excellent miscibility in polymer mixing is the use of plasticizers. The use of most plasticizers usually has some negative effects on the mechanical properties of the resulting composite and can sometimes make it toxic, which makes such polymers unsuitable for biomedical applications. This research focuses on the improvement of the miscibility of polymer composites using two-step mixing with a rheomixer and a mix extruder. Polylactic acid (PLA), chitin, and starch were produced after two-step mixing, using a compression molding method with decreasing composition variation (between 8% to 2%) of chitin and increasing starch content. A dynamic mechanical analysis (DMA) was used to study the mechanical behavior of the composite at various temperatures. The tensile strength, yield, elastic modulus, impact, morphology, and compatibility properties were also studied. The DMA results showed a glass transition temperature range of 50 °C to 100 °C for all samples, with a distinct peak value for the loss modulus and factor. The single distinct peak value meant the polymer blend was compatible. The storage and loss modulus increased with an increase in blending, while the loss factor decreased, indicating excellent compatibility and miscibility of the composite components. The mechanical properties of the samples improved compared to neat PLA. Small voids and immiscibility were noticed in the scanning electron microscopy images, and this was corroborated by X-ray diffraction graphs that showed an improvement in the crystalline nature of PLA with starch. Bioabsorption and toxicity tests showed compatibility with the rat system, which is similar to the human system.
