Effect of Ultra-High Pulse Frequency on the Resolution in the Electrochemical Deposition of Nickel

Using localized electrochemical deposition (LECD) as a mask-less direct writing methodology, metal shapes are printed. The electrochemical double-layer capacitance at ultra-high frequencies is hypothesized to cause a localized deposition and the effect of pulse frequency on the current density is modeled to predict the deposition resolution and rate of deposition. Experimental results confirm that the deposition resolution and efficiency of the LECD process increase with the increase of pulse frequency. Deposition resolution 80% smaller than the tool diameter is feasible in the LECD of nickel used with a ø 250 μm tool at 1 MHz pulsed power

No Date: IME 300 - Manufacturing Processes

To avoid an unnecessary pre-requisite hurdle, we propose removing MECH 307 (materials engineering) as a pre-req for IME 300. Relevant topics from materials science will added to course content (see syllabus). This will create more flexibility for students to take this course earlier in their studies. It will also help ease scheduling difficulties for these two courses

2/19/2020: Course Change Form IME 300

This course provides focused instruction on specific manufacturing processes. Older version of IME 100 used to teach some of these (e.g. casting, welding) and this course will update that model and include current “advanced” manufacturing topics. It will be a technical elective course for current engineering students and a requirement for BSE majors in the Advanced Manufacturing concentration

A Mathematical Model to Predict the Porosity of Locally Electrodeposited Nickel under Pulsed Voltage Conditions

Metal parts manufactured with engineered porosity offer advantages over traditional parts as they have excellent specific mechanical properties at a lower weight. This is especially of interest in the aerospace and automobile industries. Additive manufacturing allows for creating parts with computer aided design (CAD) modeled lattice structures that offer lightweight parts. However, there is a need for porous structures at the micron scale (\u3c50 µm) which cannot be achieved in a controlled manner using traditional powder-bed based metal additive manufacturing processes. Electrochemical Additive Manufacturing (ECAM) is a novel non-thermal metal additive manufacturing process capable of producing metal 3D parts with engineered porosity at the micron scale. There is a lack of understanding of the cause of porosity and controlling the porosity generated in the parts created using this process. In this paper, the effects of the electrical parameters of deposition, such as the pulse duty cycle and pulse frequency during electrodeposition, on the porosity of the manufactured parts were mathematically modeled. The model predicts that higher frequency electrodeposition leads to more porous structures. The model developed in this study can be used to predict the process parameters needed to deposit nickel microstructures with desired levels of porosity between 20 and 55 %. These model predictions were also validated by experiments. Two mechanisms for the cause of porosity in the deposits were identified. The diffusion-limited deposition phenomenon causing a lack of availability of cations results in larger sized pores and hollow structures to form on the part. The crystal growth and the nucleation process cause micron-scale pores

Investigation of the Effect of Pulsed Power During Electrochemical Surface Modification of Aluminum and Titanium Alloy

PURPOSE: Aluminum and especially titanium alloy have become the focus of many studies due to their high strength to weight ratio and biocompatibility. Surgical implants need to have a hydrophilic nature when tissue growth is desired, while they need to be hydrophobic if tissue/microbial growth is not expected. Thus, there is a need to control the wettability of these metals. SUBJECTS: This study used a sodium chlorate electrolyte to control the wettability of 1 inch by 3 inch aluminum and titanium alloy samples using an electrochemical surface modification (ECSM) process. METHODS AND MATERIALS: Duty cycle, frequency, and ECSM duration were modified while voltage was held constant at 10 V. Duty cycles of 25%, 50%, 75%, and 100% (or DC) and frequencies of 1 kHz and 100 kHz were used. Time was changed to allow the samples to have an equal active time with 2000, 1000, 667, and 500 seconds for 25%, 50%, 75%, and 100% duty cycles, respectively. ANALYSES: A first principles based theoretical model was developed in this study to predict the pulse power setting needed to achieve the desired wettability in the samples by measuring the sample mass before and after ECSM. The model was validated with experimental results. RESULTS: The surface\u27s wettability switched from hydrophilic to hydrophobic after the sample was heated in a furnace. Both the metals showed a change in contact angle behavior after evaporation of the residual water. CONCLUSIONS: This study allows for the use of ECSM as a technique to modify the surface of implants with controlled wettability for improved osseointegration

Investigating the Effect of Powder Recoater Blade Material on the Mechanical Properties of Parts Manufactured Using a Powder-Bed Fusion Process

As additive manufacturing (AM) technology grows, more industries are learning how to utilize it for their specific applications. Powder bed fusion-based AM processes such as Direct metal laser solidification (DMLS) allow manufacturers to design more intricate or lightweight parts that could not be made with traditional tools. DMLS expands the capabilities of manufacturing, but the recoater blade that spreads powder presents challenges in printing delicate details such as lattice structures and high aspect ratio features. Hard steel or ceramic blades are often used to compact powder to create smooth, even layers that result in higher strength values of parts. However, small structures can be damaged by these blade types. Alternatively, a softer rubber or carbon fiber brush can be used to make the printing process easier by not breaking the small, printed features. On the other hand, parts made with softer blades are expected to have less strength and more defects. To compare the mechanical properties of finished parts due to blade type, 3 blade materials, high-speed steel (HSS), silicone rubber, and carbon fiber brush, were compared in this study. Tensile bars, cubes, and Voronoi lattice structure pucks were printed and analyzed for tensile properties, optical density analysis, as well as compression strength or toughness. These tests are often completed by original equipment manufacturers (OEM’s) in the AM industry to qualify the machine’s process. There were no significant tensile strength differences noticed of parts based on blade type and the values were all within the tolerance of OEM specifications. Optical density analysis indicated that the rubber blade builds have a higher number of large defects, greater than 75 m, and the brush blade has a higher number of small defects, less than 75 m in size. The HSS blade has zero defects greater than 90 m. There was no significant difference in maximum compression strength for the three blades, but the HSS blade produces parts with a standard deviation of toughness that is half of the other two blades. Inconsistencies shown in the soft blade builds may be due to the nature of the soft blades wearing faster over time during each build, however, the soft recoater blades can be a useful option if the application allows for occasional inconsistency