Smart Materials in Manufacturing最新文献

In situ formation mechanism of steam Mg–Al layered double hydroxide (Mg–Al–CO₃-LDH) coatings on AZ31 and AM30 alloys was compared in presence of NaOH aqueous solution. The microstructure and elemental composition of the obtained coatings were analyzed using SEM, EDS, XRD and FTIR. The corrosion resistance of the coated samples was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and salt spray test. The results indicated that the addition of NaOH significantly influenced the morphology as well as the thickness of the prepared LDH coating. The effect of different Al–Mn phase contents of AZ31 and AM30 alloy on the growth mechanism of the LDH coatings was discussed. The addition of 0.01 M NaOH promoted the growth of the LDH coating on AZ31 and AM30 alloys. The AM30-NaOH-0.01 sample possessed the most compact and uniform surfaces as well as the maximum thickness. The corrosion current density of the samples was reduced by three orders of magnitude compared to their substrates. It was revealed that the addition of a moderate amount of NaOH in the steam would raise the pH level, which would benefit the dissolution of the aluminum phase and promote the growth of LDH coating.

Laser surface quenching (LSQ) was employed to fabricate gradient microstructures in a Ti–6Al–4V alloy. The influence of the LSQ parameters on the surface morphology, the depth of the LSQ layer, gradient microstructure, and microhardness were investigated. The results showed that as the laser energy density increases, the surface roughness and thickness of the heat-affected zone (HAZ) increase. From the internal matrix to the surface, the microstructure in the HAZ changes from the equiaxed structure to the mixt structure, martensitic structure, Widmanstätten structure, and then the oxide layer. The size of the β grains gradually decreases as the distance from the surface increases. The different microstructures and elemental distributions in the HAZ result in different microhardness values, which gradually decrease from the surface to the matrix. The laser energy density of 8.0 J/mm² is recommended to obtain a HAZ with a thickness of 1200 μm and a peak microhardness of 393 ± 7.3 H V without surface remelting. The LSQ process may help to increase the longevity of Ti–6Al–4V alloy implants by hardening the surface.

Layered double hydroxides (LDHs) are a class of two-dimensional anionic clays with adjustable structure, which have certain corrosion resistance. However, smooth growth path of LDHs nanosheets perpendicular to the substrate limits its application in the field of corrosion. Graphene oxide (GO) possess a high specific surface area and barrier properties, which provides a promising method for further improving the corrosion resistance of LDHs. In this work, we prepared three different concentrations of sodium dodecylbenzene sulfonate (SDBS) modified GO (GO:SDBS concentration ratio = 1:1, 1:2, 1:3), and present MgAlCe-LDHs@GO-SDBS composite coatings by one-step hydrothermal method with well-zigzag morphology and good corrosion resistance. GO-SDBS was successfully incorporated in the layered double hydroxide (LDHs), the corrosion current density of the MgAlCe-LDHs@GO-S₂ coatings was 1.60 × 10⁻⁸ A cm⁻², which was lower than other coatings. This one-step growth of MgAlCe-LDHs@GO-S method has potential applications in manufacture of anti-corrosion protection coatings.

Automated Ytterbium (Yb) single pass fiber laser beam welding of High Strength Low Alloy (HSLA) steel is an expensive process, so it's a need for machining process for butt joint preparation (CNC Milling and Grinding Machining) to make it less expensive to get the same material strength after constant varying joint gap. This study aims to optimize input parameters (fixed (Power and Speed), variable (Butt Joint Gap, and Focal Length)) with respect to output parameters (Distortion, Ultimate Tensile Strength (UTS), Residual Stresses (RS)) for a 4.5 mm thick 30CrMnSiA steel. Experiments and statistical modelling (using Design of Experiment) has been performed on 0–0.5 mm butt joint gap with 0.1 mm incremental size and without filler wire. The results showed that less percentage error in distortion, UTS and RS, which are 8.19 %, 2.38 % and 6.08 % respectively. In addition, 0.2–0.4 mm joint gaps show better tensile properties and almost equal to 95 % of base material (BM), by failure appearing on the BM (aside weld) due to annealed material condition. Micro-hardness measured at the fusion zone (max. 617 HV) was almost 3 times that of the base metal (max. 208 HV). Metallography study shows that fusion zone is consisted of martensite structure due to high cooling rate during laser beam welding process, so it has more strength as compared to other two zones (Heat affected zone (HAZ) and base material). Moreover, fractured tensile sample fractography study shows the ductile behavior of failure due to presence of dimples and voids.

Defects in nanomaterials have emerged as a pivotal aspect influencing their properties and diverse applications across numerous industries. This comprehensive review explores the intricate relationship between defects, primarily in carbon nanotubes and graphene, and their implications across a spectrum of applications. Beginning with an introduction delving into the significance and types of defects, the review elucidates their multifaceted impact on the mechanical, electrical, and environmental characteristics of these nanomaterials. It presents detailed analyses of studies exploring defects in carbon nanotubes and graphene, shedding light on their effects on mechanical and electrical properties, alongside characterizing methods. The paper meticulously examines the extensive array of applications involving carbon nanotubes and graphene, encompassing electronics, biomedical advancements, and considerations for environmental sustainability. Furthermore, it systematically incorporates studies highlighting the implications of defects on these applications. This review precisely examines defect engineering in nanomaterials across various industries, emphasizing the nuanced role of defects in tailoring properties for specific applications. It concludes by summarizing the integral role defects play in shaping the future of nanomaterial applications in diverse industries.

This article explores (i) the potential of polymer (nano)composites as alternatives to conventional metals in the manufacture of heat exchangers and (ii) the application of Phase Change Materials (PCMs) for thermal energy storage. Bulk polymers, despite their lower thermal conductivity in comparison with metals, have advantages such as lightweight, corrosion resistance and cost-effectiveness. The paper emphasizes methods of enhancing polymers' thermal conductivity, particularly by incorporating fillers such as ceramics and carbon-based fillers into thermoplastics. Techniques such as twin-screw extrusion and injection molding are examined for producing thermally conductive polymer composites. The study also investigates the utilization of organic PCMs, focusing on their thermal enhancement through the addition of various nanoadditives. These developments collectively pave the way for designing innovative thermoplastic heat exchangers for PCM storage. The review culminates in identifying areas requiring further research, particularly in the reliable manufacture of polycarbonate/graphene nanoplatelet composites and the optimization of the thermal performance of polymer heat exchangers through advanced heat transfer designs and simulations. The findings could lead to the realization of low-cost and efficient polymer-based heat exchangers, contributing to the evolution of thermal energy storage systems and the reduction of global warming.

The control of corrosion behavior of Mg alloys for biomedical applications is a research hotspot in the field of biodegradable metallic implant materials. In recent years, the employment of corrosion inhibitors for regulating the corrosion behavior of Mg alloys has attracted attention. In this work, a promising corrosion inhibitor for Mg alloys, Etidronate (ETN), was selected from the drugs for the treatment of osteoporosis, and its effect on the corrosion behavior of Mg–Zn–Y-Nd-Zr (ZE21C Mg alloy) in simulated body fluids was systematically studied. The results show that ETN not only reduces the corrosion rate of the alloy, but also significantly weakens its tendency of localized corrosion, which is beneficial for improving the service reliability of Mg alloy for orthopedic application. This study provides an idea for corrosion control of biodegradable Mg alloys and is of great significance for promoting their development and applications.