Key Engineering Materials Vol. 913

Abstract: Additive Manufacturing has made significant progress for numerous applications, especially in the automotive industry. Various approaches have been developed to improve and expand its application throughout the manufacturing line and produce reliable and suitable components for automotive applications. A brief overview of different 3D printing methods and materials currently used in the automotive industry is covered in this review. The advantages and drawbacks it brings to the industry, and material developments for 3D printing application for automotive is presented. The future outlook is given, and challenges that are needed to be addressed are discussed.

Abstract: The adoption of Additive Manufacturing (AM) is continuously growing due to its capability to produce complex shapes which leads to the dependence of manufacturers on AM to replace conventional manufacturing processes. One important focus of research now is on the accuracy of 3D printed products produced via the Fused Deposition Modeling (FDM). These products have great potential to be applied to tooling and other rapid prototyping applications. The aim of this study is to assess the accuracy of 3D printed Acrylonitrile Butadiene Styrene (ABS) through manual measurements of dimensions. Several sets of samples with cubic shapes were printed and measured using a digital micrometer to evaluate the dimensional accuracy of the 3d-printed parts. A 2² full factorial design was employed to investigate the effects of infill density and layer thickness on the dimensional accuracy of ABS parts.

Abstract: Additive manufacturing is a process wherein a three-dimensional object is created layer-by-layer. It offers adaptability to the geometrical complexity and customizability of the design, which is difficult to manufacture using conventional manufacturing. The aerospace industry is one of the sectors that first adopted additive manufacturing, particularly three-dimensional printing (3D printing) in the production of aircraft parts such as rocket engine components, oil fuel tanks, environmental control system ducting, combustor liner, custom cosmetic aircraft interior components, and unmanned aerial vehicle (UAV) components. The aircraft's most common materials used in the 3D printing prototype parts are acrylonitrile butadiene styrene (ABS) thermoplastic, carbon-fiber and thermoplastic composite, and nylon 12 using selective laser sintering, fused deposition modeling, or composite filament co-extrusion technology. One of the aerospace industry's challenges is ensuring the efficiency and quality of aircraft structural parts that typically require complicated manufacturing due to their complexity and variability of function. Additive manufacturing is seen to respond to this challenge by developing and prototyping 3D printed parts and exploring practical 3D printing technologies.

Abstract: Compared with current methods, additive manufacturing processes could offer a more environment-friendly and cost-effective solution in producing long lasting RFID tags for identification and sensing applications. In this work we report the fabrication of UHF RFID antennas by inkjet printing on a flexible substrate. Silver and gold were chosen as ink materials since they are more resistant to weathering than other metals, particularly for applications that require long-term reusability. We compared the print performance of a commercial silver ink and our lab-developed gold nanoparticle (AuNP) ink on polyethylene naphthalate. The printing process for each ink is described using an adopted loop antenna design optimized for 866-868 MHz frequency range. Assembled passive and battery-assisted RFID tags using single-and double-layer sintered, printed antennas coupled with a readable UHF RFID chip showed tolerable detection distances using a commercial compact reader (with short read range specifications). Additionally, we observed a more consistent print behavior and quality, and consequently longer read ranges for the gold antennas (up to 40 cm with battery). Furthermore, the silver antennas oxidized over time resulting in decreased read ranges. Overall, our results show the viability of a printable gold RFID antenna with a tag working range that may be fit for close range non-contact reading.

Abstract: Inkjet printing (IJP) has emerged as a promising additive manufacturing technique for fabrication of electrodes and sensors due to its cost-effectiveness compared to the traditional techniques, such as screen-printing. In this work, we present a planar, three-electrode system fabricated by inkjet printing on a polyethylene naphthalate (PEN) flexible substrate for rapid voltametric electrochemical analysis. An in-house formulation of aqueous-based gold ink with low temperature-sintering was used in printing the working and counter electrodes. The reference electrode was also inkjet-printed using a commercial silver ink and chlorinated to form an AgCl layer. Cyclic voltammetry studies using the ferri/ferrocyanide redox couple showed that the inkjet-printed electrode system has a comparable electrochemical performance to a commercial screen-printed electrode. Fabrication of a single inkjet-printed electrochemical 3-electrode platform consumes only about 0.5 mg Au and 0.2 mg Ag loading of ink with minimal waste during fabrication because of the additive nature of the printing technique. The 3-electrode platform operates with a microliter sample volume for analysis and can be used in aqueous media without delamination.

Abstract: Fabrication of supercapacitor (SC) electrodes plays a vital role in enhancing the electrochemical performance of SCs. Conventional fabrication techniques have limitations in fabricating the complex SC electrodes. The three-dimentional (3D) printing technique has several advantages over conventional manufacturing techniques that includes patterning capability, contact-less high-resolution, controlled material deposition, design flexibility, and multi-material compatibility. Due to these excellent qualities, considerable research efforts have been made in developing 3D printed SC electrodes. This review offers a literature update on the recent printing materials employed and the design aspects in making of SC electrodes. It also discusses the impact of critical parameters involved in various techniques of 3D printing of electrodes. Finally, the paper concludes with the scope and challenges in material/manufacturing of electrodes and the performance comparative analysis of various 3D printed structures.

Abstract: Additive Manufacturing is an emerging technology used in wide applications including, wastewater treatment. This paper presents applied techniques of Additive Manufacturing in producing a 3D-printed prototype model of a laboratory-scale wastewater treatment process. This paper aims to show the efficiency of bioremediation of freshwater algae in reducing traces of phosphate and nitrates - both known pollutants responsible for eutrophication. The study also comparatively reviews two different set-ups: stagnant and aerated. 3D printed bio-propeller, a polylactic acid-based aerator, was applied to the latter aforementioned set-up and was designed to be durable, environmental oriented, and cost-efficient. Moreover, the features and details of the 3D-printed bio-propeller emphasized its ability to promote algae harvesting by acting as a sustainable biofilm for algal growth. It is found that both set-ups show significant algae bioremediation efficiency for the synthetic nutrients. Also, the aerated set-up indicated a favorable result with the highest efficiency of 92.857% for nitrates and 41.667% for phosphate. It is concluded that the potentials of 3D printed bio-propeller as a prime component of Rotating Biological Contractor (RBC) can promote sustainable wastewater treatment.

Abstract: Scanning electron microscopy - energy dispersive X-ray spectrometry (SEM-EDS) is an elemental analysis technique widely used in various fields to identify any element in the periodic table except H, He and Li. It can be a quick way to assess the response of sensing films before deposition on sensing devices. Sensing films are usually organic thin films, but quantitative analysis of light elements and thin films is not recommended for SEM-EDS due to its limitations. In this study, SEM-EDS analysis of nitrogen in layer-by-layer polymeric thin film was optimized. The films were analyzed containing nitrogen in the form of nitrate counterions or as part of the repeat unit of the polymer. The build-up of the layer was verified by thickness measurement using atomic force microscopy. The results show that the limit for nitrogen concentration detection using nitrates was 2% by mass. Below this concentration, nitrogen content had no quantifiable response in either calculated nitrogen concentration by standardless correction methods or intensity of N Kα X-ray line. However, by adding nitrate ions to a film that already contains nitrogen in its structure the concentration was raised to 13.75%. In the range of 9.63 to 13.75%, a nonlinear response was observed using calculated nitrogen concentration while the response was linear with intensity of N Kα.

Abstract: Sea urchin zinc oxide (SU-ZnO) nanostructures were successfully synthesized using the sol-gel method and characterized by various analytical techniques. The present work reports a facile and straightforward route for synthesizing sea urchin ZnO nanostructures consisted of self-assembled ZnO nanorods with sharp tips yielding the sea urchin-like shape. The SU-ZnO nanostructures were characterized using Scanning electron microscopy and Energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared (FTIR) spectroscopy, particle size analysis (dynamic light scattering technique), and ultraviolet-visible (UV-vis) spectroscopy. The result of energy dispersive X-ray spectroscopy shows that the SU-ZnO nanostructure contains 77.30% zinc and 22.70% oxygen content. Scanning electron microscopy shows that the synthesized ZnO exhibits a sea urchin-like structure with a homogeneous and consistent size. FTIR spectroscopy confirmed the structural features and functional groups that are present in ZnO nanostructures. The particle size analysis shows that the synthesized SU-ZnO nanostructures have an average particle size of 812.62 ± 55.92 nm. The growth of SU-ZnO nanostructure was also investigated by recording the UV-Vis absorption spectra at different reaction times.