Preparation of Porous Metallic Nickel by Jet Electrodeposition

The theory and related technology of porous metallic nickel by using jet electrodeposition (JED) are reviewed, and preparation of different porosities of the porous metallic nickel samples was made by the self-developed device. The surface morphology, microstructure, grain size of the micro-cell structure of deposition were studied and analyzed by SEM, and the mechanical properties of the sample, such as surface micro hardness and compressive property were also studied. The results are as follows: the process of porous nickel preparation by jet electrodeposition mentioned in paper is capable of preparing porous metal with dendritic crystal structure as the subject porous structure. Ejection electrodeposition has great advantages in machining efficiency and cost compared with porous metal preparation process of traditional electrodeposition. The porous nickel metal sample prepared, in respects of pore distribution and porosity, are affected by electrodeposited porous dendritic crystal layers. The formula Bath A, which has a relatively low concentration of nickel ions, can make the preparation of porous dendrite structure more favorable in the way that it has more uniform compactness. Current density is the key indicator in forming ideal branched crystal; more than 60A/dm2 can make the process access to a good working state. With the increase in current density, the dendrite formation of porous structure becomes more compact. The porosity of the prepared sample is 48.7%, using jet scanning electrodeposition with the current density at 80A/dm2. The surface micro hardness of the sample reaches HV 315. The compressive yield stress of porous Nickel is 11.35 MPa, which has a large number of plastic deformations of the absorption capacity. From original data of sample energy absorption rate and fitting curve, it is known that there comes great plastic deformation, which gives the sample better absorption ability and relatively greater energy absorption rate at a relatively low flow stress.

Size Effects in Cutting With a Diamond-Coated Tool

In machining using a diamond-coated tool, the tool geometry and process parameters have compound effects on the thermal and mechanical states in the tools. For example, decreasing the edge radius tends to increase deposition-induced residual stresses at the tool edge interface. Moreover, changing the uncut chip thickness to a small-value range, comparable or smaller than the edge radius, will involve the so-called size effect. In this study, a developed 2D cutting simulation that incorporates deposition residual stresses was applied to evaluate the size effect, at different cutting speeds, on the tool stresses, tool temperatures, specific cutting energy as well as the interface stresses around a cutting edge. The size effect on the radial normal stress is more noticeable at a low speed. In particular, a large uncut chip thickness has a substantially lower stress. On the other hand, the size effect on the circumferential normal stress is more noticeable at a high speed. At a small uncut chip thickness, the stress is largely compressive.

Rapid Prototyping of Full Scale House Structures

This paper reports on the machining of a construction material (aerated concrete) with a rapid prototyping device, Shapemaker III, which is based on waterjet technology. Preliminary machining tests were carried out to investigate machining conditions (speed and pressure) of separation cuts. Cutting speeds for the waterjet were investigated for two aerated concrete construction materials; autoclaved aerated concrete (AAC) in two strengths (348 and 580 psi compressive strength) and a non-autoclaved, fiber reinforced aerated concrete (FRAC) with a 450 psi compressive strength. Cutting samples were prepared in four thicknesses (0.5, 1, 2, and 3 inches) and cut at two pressures (40 and 60 ksi). The 0.5 and 1 inch specimens were cut with good surface finish at over 600 in/min at 40 ksi. The 2 and 3 inch specimens could be cut at 320 and 80 in/min at 40 ksi, respectively. The experimental data was used in the fabrication of rapid prototyping houses with a pure waterjet machine. As results, full scale houses were fabricated with FRAC and Styrofoam. Additionally, a sub-mold of an outdoor fireplace was manufactured with Styrofoam for casting of customized aerated concrete blocks.

Effect of Film Formation Method and Annealing on Crystallinity of Poly(L-Lactic Acid) Films

Poly(L-lactic acid) (PLLA) has been shown to have potential medical usage such as in drug delivery because it can degrade into bioabsorbable products in physiological environments, and its degradation is affected by crystallinity. In this paper, the effect of film formation method and annealing on the crystallinity of PLLA are investigated. The films are made through solvent casting and spin coating methods, and subsequent annealing is conducted. The resulting crystalline morphology, structure, conformation, and intermolecular interaction are examined using optical microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It is observed that solvent casting produces category 1 spherulites while annealed spin coated films leads to spherulites of category 2. Distinct lamellar structures and intermolecular interactions in the two kinds of films have been shown. The results enable better understanding of the crystallinity in PLLA, which is essential for its drug delivery application.

Characterization of Tensile and Compressive Behavior of Microscale Sheet Metals Using a Transparent Micro-Wedge Device

The cyclic and compressive mechanical behavior of ultra-thin sheet metals was experimentally investigated. A novel transparent wedge device was designed and fabricated to prevent the buckling of thin sheets under compressive loads, while also allowing full field strain measurements of the specimen using digital imaging methods. Thin brass and stainless steel sheet metal specimens were tested using the micro-wedge device. Experimental results show that the device can be used to delay the onset of early buckling modes of a thin sheet under compression, which is critical in examining the compressive and cyclic mechanical behavior of sheet metals.

Monotonic and Cyclic Characterization of Five Different Casting Processes on a Common Magnesium Alloy

The monotonic and cyclic behavior of five different casting processes for AZ91 magnesium alloy is evaluated through microstructure characterization and mechanical testing. A passenger car control arm was cast by squeeze cast, low pressure permanent mold, low pressure permanent mold-electricmagnetic-pump, T-mag, and ablation processes. Samples were cut from twelve locations of the control arm for microstructure characterization. The grain size, porosity fraction, and porosity size were measured via optical microscopy. Different types and sizes of defects were present in each type of casting processes. The mechanical behavior characterization included monotonic tension, and fully-reversed fatigue tests. Sources of fatigue crack initiation were quantified using scanning electron microscopy. For both monotonic and cyclic loading conditions, poor mechanical performance was directly linked to the presence of large pores, oxide films, and/or pore shrinkage clusters.

Biohydrogen Production From Glycerol in Microbial Electrolysis Cells and Prospects for Energy Recovery From Biodiesel Wastes

The manufacture of biodiesel generates 10 wt% of glycerol as a byproduct. Currently, the majority of this waste glycerol is treated in wastewater treatment plants or incinerated. In this study, single chamber, membrane-free microbial electrolysis cells (MECs) was evaluated to produce hydrogen from pure glycerol and waste glycerol. At an applied voltage of 0.6 V, a maximum current density of 7.5 ± 0.4 A/m2 (238.6 ± 12.7 A/m3) was observed, the highest reported current density for a microbial electrochemical system operating on glycerol. Maximum current densities on 0.5% waste glycerin were 0.1–0.2 A/m2, much lower than those on pure glycerol, possibly due to the high salt and soap concentration in the waste glycerol. The maximum hydrogen yield on 50 mM glycerol was 1.8 ± 0.1 mol hydrogen/mol glycerol at a hydrogen production rate of 1.3 ± 0.1 m3/day/m3. The presence of methanol in the waste glycerin reduced hydrogen yield by nearly 30%. The energy efficiency on 0.5% of waste glycerol reached 200% at an applied voltage of 0.6 V. Conversion of all of the waste glycerol currently generated annually in global biodiesel manufacture to hydrogen using optimized MEC technology could generate ∼ 180 million kg of H2, representing a value of nearly $540 million, or the amount of H2 required for the production of 4.8 billion kg of green diesel. This study indicates that the generation of useful products (such as hydrogen) from waste glycerol will greatly increase the viability of the growing biodiesel industry.

Five-Axis CNC Tool Grinding: Part I—Rake Face Grinding

Grinding the helical surfaces in end-mill cutters using two-axis CNC machines is well investigated in literature. However, the grinding wheels do not have explicit geometric representations and the produced helical angles differ from the designed values. Moreover, to the best knowledge of the authors, no reliable and robust algorithm exists to grind generic shape cutters with constant normal rake angles. Thus, the first part of this work introduces a five-axis grinding process that keeps the normal rake angle constant along the rake face. The parameters that affect the shape of the tool flutes are also analyzed and studied in this part. These parameters are then optimized in the second part to obtain optimum wheel shapes grinding the tool flutes along optimum paths. Overall, the grinding process proposed grinds the tool flutes with close matching to the designed ones and replaces the complex wheel shapes commonly used by simple prismatic ones.

Size Reduction of Cellulosic Biomass in Biofuel Manufacturing: Effects of Milling Orientation on Sugar Yield

Cellulosic biofuels can reduce greenhouse gas emissions and the nation’s dependence on foreign oil. In order to convert cellulosic biomass into biofuels, size reduction of biomass is a necessary step. Most related studies in the literature claimed that smaller particles produced higher sugar yields. However, some researchers reported that this claim was not always true. The literature does not have satisfactory explanations for the inconsistence. This paper presents an experimental study on size reduction of poplar wood using a metal cutting process (milling). The results provided one explanation for this inconsistence. It was found for the first time that milling orientation had a strong effect on poplar wood sugar yield. Although smaller poplar particles had a higher sugar yield when they were milled from the same orientation, this trend did not exist for particles milled from different orientations.

Energy Consumption in Discrete Part Production

It is widely recognized that industrial production inevitably results in an environmental impact. Energy consumption during production is responsible for a part of this impact, but is often not provided in cradle-to-gate life cycles. Transparent description of the transformation of materials, parts, and chemicals into products is described herein as a means to improve the environmental profile of products and manufacturing machine. This paper focuses on manufacturing energy and chemicals/materials required at the machine level and provides a methodology to quantify the energy consumed and mass loss for simple products in a manufacturing setting. That energy data are then used to validate the new approach proposed by (Overcash et.al, 2009a, and 2009b) for drilling unit processes. The approach uses manufacturing unit processes as the basis for evaluating environmental impacts at the manufacturing phase of a product’s life cycle. Examining manufacturing processes at the machine level creates an important improvement in transparency which aids review and improvement analyses.