Search for: All records

Abstract In this study, a novel deposition technique that utilizes diethylzinc (C₄H₁₀ZnO) with H₂O to form a ZnO adhesion layer was proposed. This technique was followed by the deposition of vaporized nickel(II) 1-dimethylamino-2-methyl-2-butoxide (Ni(dmamb)₂) and H₂gas to facilitate the deposit of uniform layers of nickel on the ZnO adhesion layer using atomic layer deposition. Deposition temperatures ranged from 220 to 300 °C. Thickness, composition, and crystallographic structure results were analyzed using spectroscopic ellipsometry, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), respectively. An average growth rate of approximately 0.0105 angstroms per cycle at 260 °C was observed via ellipsometry. Uniform deposition of ZnO with less than 1% of Ni was displayed by utilizing the elemental analysis function via SEM, thereby providing high-quality images. XPS revealed ionizations consistent with nickel and ZnO through the kinetic and binding energies of each detected electron. XRD provided supplemental information regarding the validity of ZnO by exhibiting crystalline attributes, revealing the presence of its hexagonal wurtzite structure. 

Surface finishing in additive manufacturing (AM) is a technological bottleneck. The field of surface finishing of AM parts is vast because it not only focuses on roughness reduction in the hard-to-access internal surfaces but also includes the scope of adding coatings and sensors. Even though metal AM component is reaching the density and bulk microstructure at par or even better than conventionally produced components, adverse impact of surface roughness and imperfections is becoming the major obstruction. It is observed that external and internal surface roughness of AM components is a high probability cause of many unavoidable issues such as corrosion, incorrect tolerance estimations during the build stage, and the fatigue failure of parts before the expected life cycle. At present, AM field mainly focuses on improving and enhancing the internal and external surface roughness to pass the stringent qualification requirements for actual applications. To address these challenges, researchers worldwide are conducting many experiments and developing different surface finishing techniques. This paper reviews the state-of-the-art knowledge and processes of different surface finishing technology that can be applied to AM metal components. This article mainly highlights several liquid-based surfaces finishing approaches to develop promising surface microstructures on interior and exterior surfaces as a micromachining tool. The future of making strong and self-monitoring AM component requires broadening of surface finishing field and including advanced topics such as coatings and adding sensor technology. We also discuss new frontiers and the scope of future work in the surface finishing field to bring attention to related concerns and possibilities associated with making smart and strong AM components for twenty-first-century integrated engineering systems. 

Lightweight and strong components are essential for reducing energy consumption and enhancing efficiency. Lattice structures are one such geometry utilized to achieve weight reduction. This study investigates the mechanical properties of various lattice structures fabricated from Maraging Steel (EOS MS1) using the Direct Metal Laser Sintering (DMLS) method. The samples include three distinct cellular geometries: body-centered cubic (BCC), face-centered cubic (FCC), and octet truss configurations, which are subjected to tensile and compressive tests. The primary goal of this research is to evaluate the impact of heat treatment on the mechanical properties of cellular architecture under tensile and compressive loading conditions. Destructive, nondestructive testing, and simulation results were also obtained from different heat treatment processes. It was found that the age-hardened specimens performed the best overall in terms of ultimate tensile/compressive strength and elongation. The top-performing topologies in compression and tension were found to be the octet structure, as they were able to withstand the most loading and straining when compared to the other specimens. 

In order to meet the increasing societal and market demand for a diverse and well-trained Biomedical Engineering (BME) workforce, the University of the District of Columbia (UDC), the nation’s only urban land-grant institution, the District of Columbia’s only public institution of higher education, and a historically black college and university (HBCU), nurtures BME activities focused on exposure, training and cultivation through research and experiential learning. Undergraduate design projects and research-based learning opportunities in BME are key program ingredients. This paper presents the former (i.e., three, BME-related undergraduate senior Capstone Design projects that target devices to aid patient immobility) namely, the design of: 1) an ankle foot orthosis, 2) an upperlimb robotic hand prosthetic, and 3) a chairless chair lower limb exoskeleton. A current focus of the UDC BME program is Rehabilitation Engineering (i.e., interventions and devices aimed at aiding those with mobility impairments). We briefly discuss the necessity for rehabilitation-focused, biomedical-related undergraduate experiences and training for underrepresented minority students at UDC, in particular, undergraduate engineering education through multidisciplinary BME projects that foster hands-on creativity towards innovative designs. In addition to critical design experiences and undergraduate training in BME, devices may have the potential to develop into new commercial technologies and/or research projects that will aid and enhance the quality life of individuals suffering from a wide-range of mobility-related issues.