Materials Science and Engineering Commons^™

Manufacture And Mechanical Testing Of Thin Film Composites Composed Of Poly-Lactic Acid And Nanocrystalline Cellulose, Catherine E. Mohan

Materials Engineering

Society’s overuse of petroleum-based plastic products has created a waste problem that is threatening environments around the world. New efforts have been made to find a suitable replacement derived from a renewable source. Poly-lactic acid has become one of the front-runners in this search. It is derived from starches found in potatoes, corn, and other grains. There are many factors that make Poly-lactic acid-based polymers a suitable replacement for petroleum-based ones, but it still suffers from low mechanical strength due to low crystallinity percentages. Doping the polymer with nanocrystalline cellulose provides more nucleation sites for the crystallization of the polymer …

High Cycle Rotating Bending Fatigue Of 6061-T6 Friction Stir Welded Extrusions, John Chang, Travis Miller

Materials Engineering

Fatigue testing was done on friction stir welded joints of 6061-T6 aluminum extrusions. Tests were run using a rotating bending fatigue machine at stresses from 111.5 to 138.7 MPa. Failures occurred on the order of 10⁵ to 10⁷ cycles, and an S-N curve was generated based off of the failure results. After the samples failed, the location of the failure and the number of cycles to failure were noted. Fatigue samples were designed in SolidWorks with a tapered 2 inch reduced section. The 2 inch reduced section will include the entire weld region as seen from the microhardness …

Relationship Between Bagging Methods And Pre-Weld Holding Times On Porosity Formation In 2219 Aluminum Ac-Tig Welds, Mariah Grace Head, Tyson Daniel Mobley

Materials Engineering

The purpose of this study was to determine relationships between bagging methods and pre-weld holding times on the formation of porosity when AC-TIG welding 2219 aluminum. Considering the strict guidelines and specifications required within the aerospace industry, maintaining quality welds is of paramount importance to control part integrity for aerospace applications. This project focused on two parameters involved in the preparation of aluminum parts for welding: bagging method and pre-weld holding time. Welding geometry was simplified to bead-on plate instead of the standard joint welds. Radiographic analysis of the samples showed that all levels of both parameters produced “passing welds.” …

An Intercritical Heat Treatment Study Of High Strength, Microalloyed Ferrous Open Die Forgings, Kelly Elizabeth Stewart

Materials Engineering

High strength, low alloy steel is most commonly utilized in plate or sheet form-with a thickness under 4 in, one unconventional application however, is open die forging where cross-sectional area can be as large as 9.5 in by 11.5 in. When forging to larger section size than one would thermo-mechanically roll sheet steel, a new set of complications, such as variation in microstructure and mechanical properties, arise. This study investigates the heat treatment and processing options needed to negate the inherent microstructural irregularity and Charpy V-Notch (CVN) toughness variation. Intercritical heat treatment—normalizing and then quench and tempering above the A …

Characterization Of Pressure Driven And Electro-Kinetically Driven Flow In A Micro-Fluidic Chip Using Particle Imaging Velocimetry, Alexis Paige Weckel

Materials Engineering

The goal of this research is to compare electro-kinetic and pressure driven flow rates and velocity profiles (near wall vs. middle) in a microfluidic chip made of PDMS using particle imaging velocimetry (PIV) of an aqueous solution of fluorescent polystyrene (PS) particles using a laser confocal microscope (LCM). Microfluidic channels were fabricated out of PDMS using a SU-8 mold to be 25mm long and 180um by 1000um. Pressure-driven data did not show the expected parabolic profile because of the large width to depth ratio. In addition, data showed a calculated average significantly higher than the projected particle velocity through the …

Mechanical Behavior Of Compression Molded Polyethylene Terephthalate, Daniel Cole Greinke, Paul Jackson Mcewan, Dan Tran

Materials Engineering

The purpose of this project was to investigate the effects of time, temperature, and pressure on the tensile strength and elastic modulus of recycled PET. Compression molding trials were performed on shredded PET bottles to produce tensile test specimens conforming to ASTM D638-03. Aluminum molds containing the PET were mechanically fastened together at the desired pressure and heated in an electric oven. The resulting specimens were subjected to tensile testing for analysis. This screening experiment failed to generate any statistically significant data concerning the factors of interest. These preliminary results may be used to design a more systematic follow-up study.

Material Composition And Toxicology Of Cosmetic Products, Hilda Gonzalez

Materials Engineering

In today’s modern society, the U.S. Food and Drug Administration regulates many industries to protect consumers’ health; the cosmetics industry is not one of them. Through self-regulation, companies continue to sell products for topical use on the body that have been known to contain toxic chemicals with little to no testing on the effects they have on the human body. The purpose of this project was to determine the content of such known toxins in five different brands of face powders. X-Ray Diffraction (XRD) was used to verify the primary component and Inductively Coupled Plasma-Optical Emissions Spectroscopy (ICP-OES) was used …

The Environmental Impact Assessment Of Cal Poly's Manufacturing Laboratory, Yoonho Mark Kim

Materials Engineering

The purpose of the study is to obtain basic understanding of the sustainability of Cal Poly IME 144 laboratory. Since the general condition of the lab prevents precise, efficient data collection, fuzzy logic is used to provide an overview of the laboratory's sustainability. Aluminum chips, brass chips, and paper waste are identified as primary waste streams. Electric usage of the laboratory is approximately calculated based on the machines' running time. Fuzzy logic system with three inputs and one output is designed in the Matlab software environment with Simulink to simulate a model for the laboratory's sustainability. Also the study suggests …

The Effect Of Silicon On The Electrochemical Corrosion Resistance Of Carbon Steel, Loan Faget, Michael S. Rouse

Materials Engineering

The purpose of this study was to investigate how the silicon (Si) content of carbon steels affects their electrochemical corrosion resistance. Tests were conducted using concentrated HCl and carbonated water on three carbon steels with different levels of silicon: 0.02, 0,19, and 0.94 weight percent. Like H2S, the prime concern of Chevron, HCl and CO2 are corrosive components in oil refinery. Electrochemical properties were measured using a potentiodynamic test outlined in Standard ASTM G59-97: Test Method for Conducting Potentiodynamic Polarization Resistance Measurements. Previous studies have determined that adding silicon to steel increases the corrosion resistance; however, results show that corrosion …

Prediction Of Tribological Behavior Of Candidate Materials For Rotor Seals, John W. Franzino, Will F. Michul

Materials Engineering

To reduce high costs associated with manufacturing and testing materials for rotor seals, a procedure needs to be developed to quickly and accurately test candidate materials as they are released. The test should reduce the amount of fabrication required and model working conditions in order to accurately assess the tribological behavior of candidate materials. A possible solution was examined that utilized a rig meant to model operational stresses and wear. Compression modulus data was then taken in order to quantify the accumulation of damage due to microcracking, the primary mode of failure, through a damage index parameter. Testing results concluded …

Characterization Of A Thin Film Composite Membrane: Fluorinated Copolymer In A Carbon Nanotube Matrix, Eric P. Bonaventure, Michael A. Brew, Cynthia R. Shannon

Materials Engineering

IDEX Health and Science has created a thin-film composite membrane consisting of a carbon nanotube matrix impregnated with a fluorinated copolymer called Teflon® AF 2400. This membrane is being studied for use in degassing chambers of analytical instruments such as a High Pressure Liquid Chromatography (HPLC) degassing modules. The level of impregnation of the Teflon® in the carbon matrix affects the diffusion properties which are crucial for the performance of the membrane. Scanning Electron Microscopy (SEM) characterization techniques were used to measure the outer Teflon® and the inner carbon matrix layer thickness. The outer Teflon® and inner carbon matrix layer …

Development Of Low Temperature, Aqueous Synthesis Method Of Lead Sulfide Quantum Dots, Albert Nakao, Colin Yee

Materials Engineering

Quantum dots have become an active area of research in the past decade due to their unique properties. Quantum confinement effects allow for efficient spectral conversion and size tunable fluorescence and absorption peaks. Near infrared spectral converting lead sulfide quantum dots have potential applications in solar power, biological imaging and communications technology. However at Cal Poly, lead sulfide dots have not been synthesized. The quantum dot synthesis currently adapted at Cal Poly encompasses organometallic precursors at high reaction temperatures, producing cadmium selenium dots. The organometallic approach has been found to produce nanocrystals with high quality photoluminescence, but due to its …

The Effects Of Austempering And Cryogenic Processing On The Mechanical Properties Of Forged E4340 Steel For Automotive Engine Connecting Rods, Aaron Taylor Ludlow

Materials Engineering

The components in top-fuel dragster and stock car engines undergo significantly more force than their production passenger vehicle counterparts do. Therefore, they must be manufactured and processed to withstand those forces so that they do not catastrophically fail while in service. In this project, the effects of austempering and adding a cryogenic processing step to the control quench and double temper heat treatment on the tensile and hardness properties of E4340 high-strength steel were examined. Tensile test samples were machined from raw connecting rod forgings and underwent either a quench-double temper heat treatment, an austempering heat treatment, or the quench-double …

Revealing Prior Austenite Grain Boundaries Of 4340 Steel, Ryan Brierly Barrows

Materials Engineering

Grain growth during austenitization has a negative effect on fatigue strength. Several methods have been investigated in order to determine an accurate method of measuring the austenite grain size of 4340 steel. The McQuaid-Ehn method, an industry standard for evaluating austenite grain size, has been recognized to produce inaccurate results due to the coarsening of grains during extended austenitizing. A method utilized for hypoeutectoid steels, outlined by the ASTM-E112 standard, is investigated to potentially obtain more accurate results by reducing the duration of austenitizing. Studies regarding effective etching procedures for revealing austenite grains without austenitizing are also addressed. Samples are …

Mechanical Properties And Microstructures Of Incoloy 909 Rolled Rings Subjected To A Modified Forging Cycle, Colin Lee Elliott Glaves

Materials Engineering

The microstructure of rolled rings of Incoloy 909 nickel-iron-cobalt superalloy subjected to a standard customer solution and aging treatment exhibited unacceptably large grains. Samples cut from a failed ring were mounted and polished for analysis. The samples were etched with a modified Kalling’s waterless reagent and metallographic analysis was done to identify characteristic large grain structures distributed among the desired smaller grain structures. The large grains were identified and noted for comparison to later samples. Two test rings were forged out of Incoloy 909 using revised forging procedures involving reduced soak temperatures before each forging step. Metallographic samples were cut …

Lunalight - Bringing Light To The Expanding World, Gabriela M. Igel, Daniel J. Patrick, Kimberley M. Smith

Materials Engineering

The LunaLight, a solar rechargeable light and cell phone charger, addresses the lack of access to electricity faced by 1.4 billion of the world’s population (International Finance Corporation). The LunaTech team has developed a product that is bright, simple, compact, versatile and competitive with existing products. Through a partnership with the non-profit organization One Million Lights, LunaTech has improved a previous team’s design to address user feedback, concerns of durability, and manufacturability.

The LunaLight design includes a 5 component plastic housing held together by 4 screws, a surface mounted PCB, a lithium-ion (Li-Ion) battery, one high-brightness LED, a solar panel, …

The Relationship Of Barcol Hardness And Interlaminar Shear Strength In Glass Reinforced Polyester Composite Laminates, Ann E. Livingston-Peters

Materials Engineering

Chopped strand mat E-glass layers were impregnated with isophthalic marine laminating resin by hand lay-up techniques. Once the primary laminate reached the desired Barcol hardness value, the secondary laminate was applied and allowed to cure. These samples were bonded together at hardness values of 10, 30, 50, 70, and 90 Barcol. Lamination was conducted at 70°F with 35% glass fibers and 65% polyester resin catalyzed with 1.5% methyl ethyl ketone peroxide. The target thickness of each laminate was 6mm for short-beam shear testing requiring eight layers of glass and resin. Using the procedures outlined in ASTM D-2344, each sample set …

Evaluation Of Corrosion Properties Of Proprietary Metal Alloy Stents For In-Vivo Use, Michael David Bremner

Materials Engineering

To assess corrosion rates of metal alloy bio-absorbable stents an experimental set-up was designed to mimic the coronary artery environment. The artery was modeled using 4mm diameter Tecoflex tubing and the metal alloy stents were inserted into the tubing using a catheter. As is the case in cardiac surgery, the catheter with the stent and a microballoon were maneuvered to the desired position. The microballoon was then slowly inflated to expand the stent and compress it against the tubing walls. The catheter and microballoon were then withdrawn. A circulating pump system was set up to cycle fetal bovine serum (FBS) …

Fluorescence Characterization Of Quantum Dots For Use As Biomarkers, Logan M. Grimes

Materials Engineering

Fluorescence profiles of quantum dots (QDs) were characterized to select the ideal QDs for encapsulation in phospholipids for use as biomarkers to selectively adhere to cancer cells. QDs were synthesized and extracted 0, 30, 60, and 90 seconds after precursor compounds were mixed. These extractions were isolated by extraction time. Portions from each vial were coated in a zinc sulfide shelling procedure, leaving at least half of the QD solution unshelled. These samples were characterized over four days to monitor fluctuations in fluorescence. This was done utilizing an Ocean Optics spectrometer in conjunction with Spectra Suite software. The central wavelength, …

Scanning Tunneling Spectroscopy Under Atmospheric Conditions To Characterize A Tungsten Tip Stm System For Use With Hydrogen Desorption, Ross Gregoriev

Materials Engineering

The electrical surface structure of (111) n-type silicon was investigated through the use of scanning tunneling spectroscopy (STS) to develop a model to determine oxide presence on a passivated silicon surface. I-V curves were obtained with a scanning tunneling microscope (STM) using a tungsten tip on various locations of passivated silicon while the passivation layer desorbed from the surface under standard atmospheric conditions. The derivative (dI/dV) of these curves then revealed the electronic structure of the surface of the sample. Through these scans, it was determined the system was operating in the same mode as a Shockley diode. The separation …

Preparation Of A Polylactic Acid With Hydroxyapatite Reinforcement Composite, Odessa N. Quezon

Materials Engineering

Biodegradable polymers are a prime material choice for temporary biomedical devices due to its ability to degrade into non-toxic products for their use in vivo. However, polylactic acid (PLA) by itself lacks the sufficient strength and stiffness to permit their use as its properties begin to decrease as the polymer degrades. To improve the polymer’s mechanical properties, hydroxyapatite (HA) will be added to the PLA solution to act as reinforcement. The chemical property, glass transition temperature of a polymer, also plays a key role in the mechanical properties of the polymer. PLA’s glass temperature is 130⁰F. A polymer that …

Strength Testing And Material Characterization Of Cactus Spines, Mary Cooper, Jeff Goldstein, Thomas Tarlton

Materials Engineering

Twelve different species of cactus spines from 6 different genera were collected from living specimens and maintained in a dry storage environment. Spines from each species underwent 3-point bend testing, XRD testing, and SEM imaging. XRD analysis was used to verify the presence of cellulose whisker like nanocrystals and to calculate the percent crystallinity of each spine. SEM images were captured of fracture surfaces at viewing angles of 90° and 45° relative to the fracture surface, with magnifications ranging between 150x and 4,000x. A total of six spines from each species were tested in three point bending using a high-resolution …

The Effects Of Heat Treatment On The Grain Growth, Phase Evolution, And Hardness Of Newly Developed Steel-Based Hardfacing Alloys For Industrial Applications, Renee Kuzniar

Materials Engineering

Steel-based hardfacing alloys are welded onto the outside diameter of tool joints in three beads with a slight overlap between welds for underground drilling to prolong the tool joints’ life. Current hardfacing alloys have a shortened life due to cracks occurring in neighboring weld beads. To decrease cracking, the effects of composition and heat treatment on the microstructure was investigated on five alloys. Five small arc-melt circular ingots roughly 1.4 x 0.3 inches were produced. Each sample had varying amounts of C, B, Cr, Mn, Mo, Nb, Si, Ti, V, and W. The carbon levels in the alloys were .91wt%, …

Grain Size Control In Post-Forged C263 Seamless Rolled Rings, Christopher Smith

Materials Engineering

Seamless rolled rings of C263 superalloy were forged by Carlton Forge Works in Paramount, CA and sectioned for mechanical testing. The as-forged ring sections were then machined into tensile samples. To simulate cold working done after Carlton’s forging process, the C263 tensile samples were strained using an Instron tensile tester to 1, 3, 5, 7, and 9% plastic strain. These tensile samples were then solution treated at 2100°F for 30 minutes and water quenched before being aged at 1470°F for 8 hours and air cooled, following Carlton Forge Works’ heat treatment process. The gauge length sections were metallographically prepared and …

Simplifying The Testing And Calculation Of Fracture Toughness Of Thermoplastic And Thermoset Matrix Composite Materials, James Shedden

Materials Engineering

Fracture toughness, or the ability of a material to resist fast fracture by crack propagation is an important property in the use of composite materials for structural designs. Other mechanical tests such as tensile, flexure, and compression are more established and practical than testing fracture toughness. Fracture toughness testing is less commonly used because it requires specific specimens and non-conventional test methods. In composite materials specifically, delamination of the plies of materials is tested for G_IC and G_IIC values to find the critical strain energy release rate of the two types of fracture modes. The common two tests …

Development Of A Production Line Appropriate Test For Teflon Adhesion On 304 Stainless Steel 0.01-0.03" Diameter Coronary Guide Wires, Danielle Dunham

Materials Engineering

A test was developed to determine relative adhesion of Teflon-coated 304 stainless steel guide wires. Two sets of wires were provided by Abbott Vascular for testing: one set was known to have poor Teflon adhesion, the other had acceptable adhesion. A prototype device was designed and manufactured that produced a shear force on the coating by dragging the wire under a ½ inch-diameter 440C hardened stainless steel cylinder. Testing consisted of increasing the force on the wire during each consecutive pass with the cylinder until the Teflon coating failed. The force on the wire during the failure producing pass was …

Residual Stress Measurement Of 7050 Aluminum Alloy Open Die Forgings Using The Hole-Drilling Method, Alexandra Viksne

Materials Engineering

Open die forged 7050 aluminum alloy has residual stresses that can be measured by the hole-drilling method following standard ASTM E837-01. Weber Metals (Paramount, CA) assumes that the stress is uniform throughout the thickness of an open die forged plate. Four different stress relieved 7050 aluminum samples were tested to confirm if the measurements by the hole-drilling method at the surface of a plate is indicative of the stress throughout. The different stress relief methods included: two water quenched samples at temperature ranges of 60°-90°F and 120°-130°F and two samples plastically deformed by forging at room temperature 1% and 3%. …

Analyzing The Flexural Properties Of Self-Constructed Bamboo Laminates, Brett Dorren

Materials Engineering

Bamboo plies of 1/8" and 1/32" thicknesses were glued together to form multiple unidirectional and cross-ply laminates that measured 12" by 12". The thickness of each laminate was between 0.25" and 0.375". All laminates were pressed together with a Tetrahedron MTP-10 bench top precision press at 75°F and 1000 lb_f for 40 minutes. Laminates were then cut with a band-saw into four 3" by 12" test specimens, 24 hours after pressing. Each test specimen was three-point bend tested to identify the modulus of rupture (MOR) and apparent bending stiffness. Three-point bend testing was also performed on laminates that were …

Evaluation Of High Phosphorus Electroless Nickel Platings To Protect Carbon Steel Heat Exchangers In Seawater Service, Nathan Brink

Materials Engineering

The purpose of this project was to determine the suitability of using a high phosphorus electroless nickel (HPEN) coating to prevent corrosion in carbon steel heat exchangers in seawater service. 1 in. x 4 in. samples were cut from ¼ in. SA-516-70 pressure vessel plate, pickled to remove mill scale, dressed with 300 grit sand paper and sent out for plating with 2 mils of HPEN. Due to a clerical error during plating, samples were plated to a significantly lesser extent than requested. Samples were plated with approximately 0.6 mils of HPEN versus the 2 mils requested, however this was …

Measuring The Mechanical Properties Of A Newly Developed Discontinuous Carbon Fiber And Epoxy Composite, Morgan Adams

Materials Engineering

Engineering firm Pratt & Miller have developed a new and previously untested carbon fiber/epoxy composite using a spray lay-up process similar to a process commonly used in fiberglass production. This new composite is made by using a pneumatic chop gun that simultaneously cuts the carbon fibers to a specific length and deposits the chopped fibers and resin onto surface of an exposed mold surface. The composite is then rolled down to flatten and better wet the fibers and then the whole mold is vacuum bagged at room temperature to cure. The flexural stiffness and flexural strength of the composite with …