Materials Science and Engineering Commons^™

Challenges In Transdisciplinary, Integrated Projects: Reflections On The Case Of Faculty Members’ Failure To Collaborate, Linda Vanasupa, Kathryn E. Mccormick, Carolyn J. Stefanco, Roberta J. Herter, Margot Mcdonald

Materials Engineering

In this article we describe the challenges of transdisciplinary teamwork involving four faculty members from dissimilar epistemological traditions in the process of developing a manuscript on the lessons learned in our teaching collaboration. Our difficulty originated in implicit mental models and assumptions that caused incongruence between our intent to collaborate and the (habituated) relationship structure of the partnership. The dynamics are described through the lens of Tannenbaum and Schmidt’s leadership model and Aristotle’s causality. We suggest that successful collaboration necessitates careful attention to the process of establishing the collaboration, its structure, and the metacognitive capacities to see one’s own thinking, …

The Synthesis And Characterization Of Gold And Silver Nanoparticles In Formal And Informal Settings, Mathew Wynn

Materials Engineering

Silver nanoparticles were synthesized through the reduction of AgNO3 using NaBH4. The borohydride anions were adsorbed onto silver nanoparticles. The repelling forces of the borohydride anions prevented the aggregation of particles, but the addition of an electrolyte or agitation induced aggregation. A yellow hue was given off by the silver nanoparticle sol that, using a spectrophotometer, had plasmon resonance at 386 nm. The silver nanoparticles were estimated to be 10 to 20 nm in diameter. Gold nanoparticles were synthesized through the reduction of HAuCl4 using Na3C6H5O7. The gold nanoparticle sol gave off a red hue that had plasmon resonance at …

Characterization And Analysis Of Low Room Temperature Ductility Nickel-Based Superalloy 718 Plus For Aircraft Engine Forgings, Jonathon Bracci

Materials Engineering

Schlosser Forge Co. forges low pressure turbine (LPT) cases from the nickel based superalloy 718 Plus using the ring rolling forging process. Schlosser has been experiencing low room temperature ductility problems in a number of their 718 Plus LPT cases. LPT cases are required to pass a 4D tensile test at room temperature with a minimum of 15 percent elongation. The ductility problem was reduced by increasing the forging temperature from 1825˚F to 1850˚F. Analysis was performed on 718 Plus samples taken from forged LPT cases that failed the room temperature ductility requirement and ones that passed the requirement. The …

Blunt Impact Performance Evaluation Of Helmet Lining Systems For Military And Recreational Use, Jaclyn Siniora, Ryan Taylor, Darren Suey

Industrial Technology and Packaging

With the increasing problem in collegiate athletes experiencing injuries to the brain, different helmet liners where put to the test to see which liner provided athletes the greatest protection under specific conditions.

This senior project evaluates five different liners in football helmets. Each of the helmet liners were tested at three different temperatures: hot, cold, and ambient. Each helmet had seven different impact locations which were put to the test. The project was designed to be used to test ACH military combat liners as well. Due to shipping bottle necks the ACH combat liners have been left to future Cal …

Determining An Inorganic Mineralization Process To Inhibit Organic Degradation And Preserve The Dimensional Stability Of Bamboo, Eric Hahn

Materials Engineering

Bamboo is a renewable natural composite with potential as both a construction and synthesis material. The components of bamboo are cellulosic vascular bundles imbedded within a lignin matrix that create a porous hierarchical structure. This structure has low density while maintaining high strength, toughness, and elasticity, but is susceptible to organic decay. A study was performed to evaluate the effect of varying bamboo culm age (1-3 years) and density (0.72-1.05 g/cm³) on the ability to control inorganic mineral precipitation to prevent degradation and preserve dimensional stability of the organic matrix. Internodal culm samples were immersed in solutions of …

Biaxial & Twist Testing Of Composite Carbon-Fiber Sandwich Panels For Automotive Racing Vehicles, Erik Eckberg

Materials Engineering

Composite sandwich panels were constructed with 4-ply plain weave carbon-fiber/epoxy face sheets in the 0^o/45^o/0^o/45^o orientation and 1/8^th inch Nomex honeycomb core. The panels were cut into 5-inch square test plates for mechanical testing. All testing was done on a fixture designed and fabricated by Pratt & Miller Engineering and installed on an Instron testing system at Cal Poly. The twist test was performed by supporting diagonal corners of the plate while simultaneously loading the opposite two corners at a crosshead rate of .06 in/min (ASTM 3044-94R11). Out of 10 panels tested, …

The Design And Fabrication Of A Silicon Membrane For Electrostatic Actuation, Elizabeth L. Brooks

Materials Engineering

An electrostatically actuated silicon membrane was designed and fabricated utilizing a siliconon- insulator wafer. The SOI wafer contains three layers- a 400μm thick “handle” layer of silicon followed by a 2μm thick oxide layer topped with a 20μm thick “device” layer of silicon. The embedded oxide layer acts as an etch-stop during silicon etching, leaving a thin membrane of consistent thickness on the device side. The device dimensions were chosen to provide acceptable membrane deflection predicted by calculations and Finite Element Analysis. A microfabrication process plan was designed to produce thin membranes appropriate for electrostatic actuation. A 700nm layer of …

Effects Of Beta Stabilizers On Quench Delay Susceptibility Of Ti-6al-4v, Kyle Logan

Materials Engineering

Tensile samples of Titanium 6Al-4V (Ti-6Al-4V) were machined from forgings containing rich and poor amounts of beta stabilizers in their compositions. The tensile samples were each heat treated two times. In the first round of heat treatments, the samples were either beta solution treated (BST), or solution treated (ST). Each sample was water quenched with varying quench delays of 10, 20, and 30 seconds. BST treated specimens were then overaged at 1350°F for 2 hours and air cooled (BSTOA); while the ST treated samples were aged at 990°F for 6 hours and air cooled (STA). Following heat treating, the tensile …

Evaluation Of Corrosion Properties For Use Of Az31b In Bioabsorbable Stents And In Vivo Corrosion Rate Prediction Using Fea, Jared Vidales, Austin Schader, Jenna Jerman, Michael Turovskiy

Materials Engineering

AZ31B was heat treated to evoke more controlled and uniform corrosion. 1/16” diameter AZ31B wire was cut into six samples each 1” long. The samples underwent heat treatments following ASTM B661-06. Samples were weighed and placed into three different in vitro environments. In the first scenario two samples of each heat treatment were individually placed in 50 ml of saline solution at 0.9% sodium, in a static test tube at 37°C temperature. Two samples were placed in 100 ml of 0.9% saline solution in a 250 ml stirring beaker with an average whirlpool depth of 1”. Two of each sample …

Effects Of Alternate Cementitious Materials On Compressive Strength And Environmental Impacts Of Cement Mix Designs., Mitchell R. Bush

Materials Engineering

Specific proportions of Portland cement, fly ash, and blast furnace slag cement mixtures where chosen by a ternary phase diagram to be investigated. By experimental testing and company data history fly ash was limited to not exceed 30% and contribution of Portland cement must be over 50%. Ten chosen mix designs were batched by following ASTM C305-94 and cured for twenty-eight and forty-two days, the extended cure length allows the reaction of pozzolanic material with calcium hydroxide to complete. Compressive strength testing at forty-two days yielded low strength for mix designs with 20% or less Portland cement compared to our …

The Characterization And Comparison Of Biochar Produced From A Decentralized Reactor Using Forced Air And Natural Draft Pyrolysis, Leah Herbert, Ian Hosek, Rishi Kripalani

Materials Engineering

The soil additive properties of biochar have proven both effective and globally beneficial, but depend heavily on feedstock used and process conditions. This study characterizes how forced and natural draft air flows affect the biochar’s soil amendment potential. Biochars manufactured from two pine species of feedstock, in timber and pellet form, were compared against a designer biochar. The designer biochar held the lowest C:N ratio (57.43), followed by the natural draft pellets (199.5), forced air timber (282.5), forced air pellets (422.7), and natural draft timber (503.7). The designer char had the largest cation exchange capacity at 138.5 cmolc/kg; the decentralized …

Microstructural Characterization Of Ti-6al-4v And Its Relationship To Sample Geometry, Blake Gaspar

Materials Engineering

A problem exists with a part produced by forging made by Shultz Steel of Ti-6Al-4V in the variance of properties throughout the part. There is one specific region that exhibits the most variance. The purpose of the report is to determine any microstructural differences within the region of interest in the part. When microstructures of the inner section and outer section of the part were looked at it was determined that they exhibited a martensitic structure. There was a noticeable difference in the lath structure between sections. The outer region contained larger more widely spread laths of an average length …

Artificial Alveolar-Capillary Membrane On A Microchip, Keith Male

Materials Engineering

A microfluidic device was synthesized out of polydimethyl siloxane (PDMS) to simulate the structure of the alveolar-capillary interface of the human lung. Soft lithography techniques were used to build a mold structure out of SU-8 epoxy at heights ranging from 30µm to 110 µm on a silicon substrate, with the 70 µm structure working the best. A mixture of 10:1 Sylgard 184 elastomer was then cast using the mold, and cured at a temperature of 80^oC. For the porous membrane, the PDMS was spun on at 6000rpm for 30 seconds using a spin coater to produce a membrane …

Bond Strength Characterization Of Su-8 To Su-8 For Fabricating Microchannels Of An Electrokinetic Microfluidic Pump, Nash Anderson

Materials Engineering

Photosensitive negative resist polymer layers of SU-8 2050 were adhered to 100 mm n-type silicon and Pyrex wafers via spin coating. These wafers were then bonded together at various temperatures of 100 ͦC, 120 ͦC, 140 ͦC, 150 ͦC, 160 ͦC, and 180 ͦC. The target thickness of each SU-8 layer was 100 µm. Photolithography was used to create microfluidic channels within the SU-8. An n-type silicon wafer and a Pyrex wafer, each with an SU-8 layer, were brought together on the “hard bake” or final step of SU-8 polymerization. A pressure of ~300 KPa was applied during the hard …

Design And Fabrication Of Serpentine-Hinged Silicon Micro-Mirror Devices, Nicholas Wiswell

Materials Engineering

Seven different actuating micro-mirror designs were created and verified via finite element analysis. Two were straight torsion beam hinge designs representative of previous work at Cal Poly; the remaining five were new designs incorporating serpentine hinges. The surface area of these mirror devices ranged from 0.5 square millimeters to 12.5 square millimeters. Geometric patterns representing the device profiles were created and used to obtain photolithographic masks. Beginning with a 400μm thick, 100mm diameter silicon on insulator wafer, a silicon dioxide layer was thermally grown on the surface at 1050 degrees Celsius. Positive photoresist was then spun onto the wafer at …

Design And Development Of An Interactive Materials-Based Learning Kit For K-4 Grade Levels, Thomas Agasid, Santiago Caceres, James Woodhead

Materials Engineering

The Materials Safari Adventure kit was designed to help introduce basic materials concepts to young audiences in kindergarten through fourth grade levels. The primary goal of this project was to design a tool to spark an interest in materials science for young children, while revealing the field of materials science to parents and educators. The final kit design incorporates a safari theme to encourage imagination and promote self-directed learning through the interaction with materials. Materials were selected to showcase a range of properties within three materials classes: metals, polymers, and natural woods. A total of 9 materials were chosen for …

Improving Solar Cell Performance Using Cdse/Zns Core/Shell Quantum Dots In A Spectral Conversion System, Buddy Bump

Materials Engineering

Solar cells have been found to absorb light more efficiently and effectively when the energy of incoming photons matches the electronic band gap of the solar cell. Spectral conversion of light from UV to lower energy wavelengths can improve solar cell efficiency an estimated 14.5%. Cadmium Selenium/Zinc Sulfide Core/Shell quantum dots have been successfully embedded in PDMS silicone elastomer. Using a Keithley 2400 Electrometer with Labview software, voltage and current characteristics have been recorded in steps of 10 mV with a wait time of 250 ms on a commercially available solar cell using an artificial solar spectrum created by a …

Morphology And Roughness Of Al2o3 On Ferritic Stainless Steel Foil For Diesel Catalytic Converter Applications, Megan Butala

Materials Engineering

The improved thermal properties of metal-substrate catalytic converters enable effective catalysis sooner after ignition than traditional ceramic monoliths, resulting in less harmful emissions. ACAT Global, a manufacturer of stainless steel catalytic converters, uses ferritic stainless steel substrates for low temperature catalytic converters for diesel automobiles. Production begins with an oxidizing heat treatment to increase surface roughness. The success of the second production step, the application of catalyst-containing ceramic slurry (washcoat), depends on the surface roughness that results from oxidation. Formation of the primary oxide of interest, alumina (Al₂O₃), is controlled by the stainless steel foil composition, …

Discontinuous Grain Boundaries Of Forged René 41, Steven Crump

Materials Engineering

Forged components must pass a grain size specification (grain size, distribution) for acceptance in an application. The varying amounts of plastic deformation during forging can lead to abnormally large recrystallized grain sizes in certain regions of the part, which will not pass specification. The question exists whether these abnormally coarse grains are truly comprised of poly crystalline fine grains with grain boundaries resistant to etching techniques. To investigate this abnormal grain size effect, a cross section of a forged René 41 nickel-based superalloy aircraft engine ring was cut and sectioned into six segments. Those segments were then prepared for microstructural …

Analyzing The Corrosion Resistance Of Ni-Shield 200 Coatings At Different Temperatures When Exposed To Sulphuric Acid, Alex Hussinger

Materials Engineering

Six steel samples each were twin wire arc sprayed with Hastelloy C-276 or Nickel-Shield 200 coatings approximately 0.020″ thick. These samples were then cut into 3″ by 3″ squares. A 2″ diamond grit hole saw was used to abrade and polish to a smooth surface a ring in the middle in order to get an O-ring mechanical seal. The samples were then weighed and loaded into a jig that started from the bottom up with a stainless steel plate, then the sample, then a Viton O-ring, a ¾″ thick glass plate with a 1 3/4″ hole cut in it, another …