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Articles 1 - 30 of 84
Full-Text Articles in Engineering Science and Materials
A Polar Turbulence Invariant Map With Applicability To Realisable Machine Learning Turbulence Models, James G. Wnek, Christopher Schrock, Eric M. Wolf, Mitch Wolff
A Polar Turbulence Invariant Map With Applicability To Realisable Machine Learning Turbulence Models, James G. Wnek, Christopher Schrock, Eric M. Wolf, Mitch Wolff
Mechanical and Materials Engineering Faculty Publications
Invariant maps are a useful tool for turbulence modelling, and the rapid growth of machine learning-based turbulence modelling research has led to renewed interest in them. They allow different turbulent states to be visualised in an interpretable manner and provide a mathematical framework to analyse or enforce realisability. Current invariant maps, however, are limited in machine learning models by the need for costly coordinate transformations and eigendecomposition at each point in the flow field. This paper introduces a new polar invariant map based on an angle that parametrises the relationship of the principal anisotropic stresses, and a scalar that describes …
Creating Blood Analogs To Mimic Steady-State Non-Newtonian Shear-Thinning Characteristics Under Various Thermal Conditions, Hang Yi, Alexander Wang, Christopher Wang, Jared Chong, Chungyiu Ma, Luke Bramlage, Bryan Ludwig, Zifeng Yang
Creating Blood Analogs To Mimic Steady-State Non-Newtonian Shear-Thinning Characteristics Under Various Thermal Conditions, Hang Yi, Alexander Wang, Christopher Wang, Jared Chong, Chungyiu Ma, Luke Bramlage, Bryan Ludwig, Zifeng Yang
Mechanical and Materials Engineering Faculty Publications
Blood analogs are widely employed in in vitro experiments such as particle image velocity (PIV) to secure hemodynamics, assisting pathophysiological diagnoses of neurovascular and cardiovascular diseases, as well as pre-surgical planning and intraoperative orientation. To obtain accurate physical parameters, which are critical for diagnosis and treatment, blood analogs should exhibit realistic non-Newtonian shear-thinning features. In this study, two types of blood analogs working under room temperature (293.15 K) were created to mimic the steady-state shear-thinning features of blood over a temperature range of 295 to 312 K and a shear range of 1~250 s−1 at a hematocrit of ~40%. Type …
Ab Initio Simulations For Oxidation Of An Ultra-High Temperature Ceramic (Hfb2), Wesley I. Black
Ab Initio Simulations For Oxidation Of An Ultra-High Temperature Ceramic (Hfb2), Wesley I. Black
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Ultra-High Temperature Ceramics are a class of ceramics that possess high strength and melting points in excess of 3000°C. These ceramics are promising for aerospace applications, where materials need to endure high-temperature and high-stress environments. Utilizing ab initio simulations, this thesis research focuses on the atomistic details of oxidation for a typical ultra-high temperature ceramic material, namely hafnium diboride. The simulations provide energy barriers for transition from the initial to final structures via transition states on the (0 0 0 1) surface. These result in estimates for reaction rates and other thermodynamic features that are essential for assessing applicability under …
Study Of Fiber-Loaded Slurries For Ceramic Matrix Composite Fabrication By Additive Manufacturing, Gaspard Matondo
Study Of Fiber-Loaded Slurries For Ceramic Matrix Composite Fabrication By Additive Manufacturing, Gaspard Matondo
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We studied the additive manufacturing of an alumina-matrix composite reinforced with alumina fibers using the Admatec Admaflex 3D printer, which utilizes digital light processing technology. Oxide-oxide composites are composite materials in which both the matrix and the reinforcing element are ceramic oxides. Monolithic alumina ceramic exhibits a good combination of thermal and mechanical properties, including thermal shock resistance, high melting point, thermal oxidation resistance, good thermal conductivity, hardness, and mechanical strength. However, it is very brittle. Introducing alumina fiber as a reinforcing material into the alumina matrix is expected to enhance mechanical properties, particularly toughness, making the ceramic matrix composite …
Experimental Study Of Drag Characteristics And Dust Removal Performance Of A Hybrid Wet-Filter Precipitator, Hang Yi, Zifeng Yang, Deqiang Chang, Xinjiao Tian, Jingxian Liu
Experimental Study Of Drag Characteristics And Dust Removal Performance Of A Hybrid Wet-Filter Precipitator, Hang Yi, Zifeng Yang, Deqiang Chang, Xinjiao Tian, Jingxian Liu
Mechanical and Materials Engineering Faculty Publications
With their advantages of high dust removal efficiency and low drag characteristics, hybrid wet-filter precipitators have great potential for dust control in coal mines, but the underlying mechanisms are not well understood. In this study, to help fill this knowledge gap, a hybrid wet-filter precipitator consisting of a 40-layer metal filter and a defogger device is designed and a prototype is constructed. Experiments are conducted to investigate its drag characteristics under wind velocities from 0.85 to 5.68 m/s and its dust removal performance under wind velocities of 2 and 4 m/s. On the basis of results with the initial design, …
Using Dft On Ultrasound Measurements To Determine Patient-Specific Blood Flow Boundary Conditions For Computational Hemodynamics Of Intracranial Aneurysms, Hang Yi, Zifeng Yang, Luke Bramlage, Bryan Ludwig
Using Dft On Ultrasound Measurements To Determine Patient-Specific Blood Flow Boundary Conditions For Computational Hemodynamics Of Intracranial Aneurysms, Hang Yi, Zifeng Yang, Luke Bramlage, Bryan Ludwig
Mechanical and Materials Engineering Faculty Publications
Boundary conditions (BCs) is one pivotal factor influencing the accuracy of hemodynamic predictions on intracranial aneurysms (IAs) using computational fluid dynamics (CFD) modeling. Unfortunately, a standard procedure to secure accurate BCs for hemodynamic modeling does not exist. To bridge such a knowledge gap, two representative patient-specific IA models (Case-I and Case-II) were reconstructed and their blood flow velocity waveforms in the internal carotid artery (ICA) were measured by ultrasonic techniques and modeled by discrete Fourier transform (DFT). Then, numerical investigations were conducted to explore the appropriate number of samples (N) for DFT modeling to secure the accurate BC by comparing …
Numerical Investigation Of Supersonic Flow Over A Wedge By Solving 2d Euler Equations Utilizing The Steger–Warming Flux Vector Splitting (Fvs) Scheme, Mitch Wolff, Hashim H. Abada, Hussein Awad Kurdi Awad Kurdi Saad
Numerical Investigation Of Supersonic Flow Over A Wedge By Solving 2d Euler Equations Utilizing The Steger–Warming Flux Vector Splitting (Fvs) Scheme, Mitch Wolff, Hashim H. Abada, Hussein Awad Kurdi Awad Kurdi Saad
Mechanical and Materials Engineering Faculty Publications
Supersonic flow over a half-angle wedge (θ = 15°) with an upstream Mach number of 2.0 was investigated using 2D Euler equations where sea level conditions were considered. The investigation employed the Steger–Warming flux vector splitting (FVS) method executed in MATLAB 9.13.0 (R2022b) software. The study involved a meticulous comparison between theoretical calculations and numerical results. Particularly, the research emphasized the angle of oblique shock and downstream flow properties. A substantial iteration count of 2000 iteratively refined the outcomes, underscoring the role of advanced computational resources. Validation and comparative assessment were conducted to elucidate the superiority of the Steger–Warming flux …
Production Of Cerium Oxide And Zinc Sulfide Composites, Ted Autore
Production Of Cerium Oxide And Zinc Sulfide Composites, Ted Autore
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Zinc sulfide has an infrared cutoff in the LWIR, but its low hardness makes it susceptible to rain erosion and abrasion. A composite of cerium oxide and zinc sulfide that retains an infrared cutoff in the LWIR, and with hardness higher than pure zinc sulfide is a potential solution to the rain erosion and abrasion issue. Several different processes were undertaken in this project to produce such a composite. The different reactions between ZnS and CeO2 were researched, along with the effects of different processing parameters. Composite samples were made that had a better hardness than zinc sulfide but did …
Deep Learning Based Optical Flow Analysis Of High-Speed Flows, Daniel H. Zhang, Zifeng Yang
Deep Learning Based Optical Flow Analysis Of High-Speed Flows, Daniel H. Zhang, Zifeng Yang
Mechanical and Materials Engineering Faculty Publications
Two-dimensional Rayleigh scattering imaging is utilized to quantify the high-speed flow velocity by employing deep learning based optical flow analysis, along with density fields from Rayleigh scattering intensity profiles.
Generating Blood Analog For Laser Induced Fluorescent Particle Image Velocimetry, Chungyiu Ma, Jared Chong, Hang Yi, Zifeng Yang, Luke Bramlage, Bryan Ludwig
Generating Blood Analog For Laser Induced Fluorescent Particle Image Velocimetry, Chungyiu Ma, Jared Chong, Hang Yi, Zifeng Yang, Luke Bramlage, Bryan Ludwig
Mechanical and Materials Engineering Faculty Publications
To mimic blood non-Newtonian viscosity features under designated temperatures from 305 to 315 K, transparent blood analogs were generated by the mixture of xanthan gum and deionized water with fluorescent particles for laser induced fluorescent particle image velocimetry.
3d Flow Field Quantification In An Artery Model Using Optical Flow Method Based On Simulated Multi-Angle Angiography, Zifeng Yang, Hang Yi, Luke Bramlage, Bryan Ludwig
3d Flow Field Quantification In An Artery Model Using Optical Flow Method Based On Simulated Multi-Angle Angiography, Zifeng Yang, Hang Yi, Luke Bramlage, Bryan Ludwig
Mechanical and Materials Engineering Faculty Publications
3D flow field in a numerically simulated arterial model is quantified using the three-dimensional optical flow method based on simulated simultaneous multi-angle X-ray angiography of the blood flow with contrast agent perfusions.
Fabricating And Analyzing Liquid And Polymer Electrolytes For Sodium Ion Batteries, Kekule Augustine
Fabricating And Analyzing Liquid And Polymer Electrolytes For Sodium Ion Batteries, Kekule Augustine
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The abundance and the cost-effectiveness of sodium resources have made sodium-ion batteries (SIBs) viable alternatives to lithium-ion batteries. Developing low-cost and high-performance electrolytes is one of the key areas for the advancement of SIB technology. The highly conductive liquid or solid electrolytes have the potential for practical sodium-ion battery applications. Long-term stability, alternative polymers, and full-cell integrations are other avenues that need further research to improve scalability and performance for SIBs. This research covers preparing and evaluating liquid and polymer electrolytes, with a focus on ionic conductivities. Liquid electrolytes were prepared by the dissolution of different sodium salts including NaCl, …
Dual Airfoil Testing System, Zifeng Yang, Collin Charvat, Jack Stafford, Kyle Mathews, Logan Kelly
Dual Airfoil Testing System, Zifeng Yang, Collin Charvat, Jack Stafford, Kyle Mathews, Logan Kelly
Mechanical and Materials Engineering Faculty Publications
A dual airfoil testing system includes a platform including a frame defining a chamber that is configured to receive a horizontal flow of air for testing a first airfoil and a second airfoil contained in the chamber and a control system including a controller to control a first attack angle stepper motor, a second attack angle stepper motor, at least one gap stepper motor, and at least one stagger stepper motor. The controller is configured to automatically control and adjust the stepper motors to control and adjust the attack angle of the first airfoil, the attack angle of the second …
Morphology And Hemodynamics Of Cerebral Arteries And Aneurysms In A Rare Pair Of Monozygotic Twins, Hang Yi, Zifeng Yang, Luke C. Bramlage, Bryan R. Ludwig
Morphology And Hemodynamics Of Cerebral Arteries And Aneurysms In A Rare Pair Of Monozygotic Twins, Hang Yi, Zifeng Yang, Luke C. Bramlage, Bryan R. Ludwig
Mechanical and Materials Engineering Faculty Publications
In this preliminary study, the underlying pathophysiology mechanisms of cerebral aneurysms (CAs) in monozygotic twins (MTs) were investigated via a rare pair of MTs (twin A and twin B) involving four reconstructed arterial models using preclinical information. First, dimensions and configurated outlines of three-perspective geometries were compared. Adopting an in-vitro validated numerical CA model, hemodynamic characteristics were investigated in the MTs, respectively. Despite expected genetic similarities, morphological comparisons show that configurations of cerebral arteries exhibit significant differences between the twins. The ICA size of twin A is larger than that in twin B (2.23~25.86%), varying with specific locations, attributing to …
Hemodynamic Investigations In Intracranial Aneurysms: A Commentary, Hang Yi, Mark Johnson, Luke Bramlage, Zifeng Yang, Bryan Ludwig
Hemodynamic Investigations In Intracranial Aneurysms: A Commentary, Hang Yi, Mark Johnson, Luke Bramlage, Zifeng Yang, Bryan Ludwig
Mechanical and Materials Engineering Faculty Publications
Intracranial aneurysms (IAs) are abnormal bulges in a blood vessel in the brain that have a potential to rupture and even causing a stroke, which can lead to lasting brain damage, long-term disability, or even loss of life. It has been widely acknowledged that hemodynamic factors, e.g., instantaneous wall shear stress, time-averaged wall shear stress, wall shear stress gradient, gradient oscillatory number, oscillatory shear index, pulsatile blood flow waveform (flow rate magnitude and shape, physical flow period), relative residence time/turnover time, blood pressure, and vortex (i.e., size, location, and numbers), have a close relationship with the pathobiology (i.e., initiation, growth, …
Direct Ink Write Processing Of Signal Crossovers Using Aerosol Jet Printing Method, Lucas A. Clark
Direct Ink Write Processing Of Signal Crossovers Using Aerosol Jet Printing Method, Lucas A. Clark
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Electronics in different applications, such as in medical imaging devices, radar systems, communication transmitters, and optical drives, often require various power and signal lines to be integrated at board level. In such cases, different lines may cross over one another in three-dimensional space for efficient electronic integration. Crossovers are usually achieved by adding additional layers to a PCB. However, these additional layers increase the cost, weight, and complexity of the component. By creating a process and structure to offer board-level heterogenous integration, these factors may be reduced. RF-DC crossovers were designed and additively manufactured using an aerosol jet printer. Benzocyclobutene …
Processing And Characterization Of Inkjet Printed Batio3/Su-8 Nanocomposite Dielectrics, Mustapha A. Muhammad
Processing And Characterization Of Inkjet Printed Batio3/Su-8 Nanocomposite Dielectrics, Mustapha A. Muhammad
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The persistent demand for flexible and wearable electronic components in healthcare, aerospace, media, and transit applications has led to a significant shift from traditional electronics processes to printed electronics. Printed electronics are anticipated to establish itself as the industry's dominant force due to their enhanced flexibility, rapid prototyping capabilities, and seamless integration with everyday objects. They are cost-effective and have the scalable option for large-scale production because additive manufacturing techniques are used. Among the various printing methods available, inkjet printing has recently gained popularity for printing electronics, especially capacitors that require precise and complex structures on different substrates. Inkjet printing …
Rheological Modeling And Inkjet Printability Of Electrode Ink Formulation For Miniature And Interdigital Lithium-Ion Batteries, Habib Temitope-Adebayo Ajose
Rheological Modeling And Inkjet Printability Of Electrode Ink Formulation For Miniature And Interdigital Lithium-Ion Batteries, Habib Temitope-Adebayo Ajose
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The rapid advancement of technology has resulted in a greater need for effective energy storage systems to meet the demands of the transportation and electronics industries. Among various energy storage systems, batteries are the most widely used, primarily because of their ability to store significant amounts of energy. In addition, lithium-ion batteries are prevalent for powering portable electronic devices due to their long cycle life, high energy density, and high operating voltage. The traditional doctor-blade approach has been used over the years for producing batteries. Currently, research is being directed to additively manufacture Li-ion batteries via Drop-on-Demand Inkjet Printing with …
Comparative Study Of Mof's In Phosphate Adsorption, Eniya Karunamurthy
Comparative Study Of Mof's In Phosphate Adsorption, Eniya Karunamurthy
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High concentrations of phosphate are known to adversely affect the environment. Excess phosphate can lead to eutrophication that eventually fosters uncontrollable growth of aquatic plants and algae. This can result in depletion of oxygen content which adversely impacts underwater organism’s survival rates. Metal organic frameworks (MOFs) consist of organic linkers in conjunction with metal ions or clusters arranged within a crystalline structure. They are highly porous and have larger surface area due to their ability to possess extensive void spaces while remaining bulky in nature. MOFs can absorb phosphate from aqueous solutions. We have investigated the use of commercially available …
Characterization Of Aerosol Jet Printed Silver Thin Films Sintered By A Scanning Laser, William A. Metzger
Characterization Of Aerosol Jet Printed Silver Thin Films Sintered By A Scanning Laser, William A. Metzger
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Direct write printing, which is part of additive manufacturing (AM) technology, offers unique capabilities that can complement traditional methods of electronics fabrication. Printing of electrical interconnects via aerosolization is one of the areas in AM that is very important in electronics fabrication. Post-print sintering is a critical step in printed electrical interconnects because it strongly influences the electrical resistivity of the interconnects. Interconnects require the lowest possible resistivity to achieve better performance. Thermal sintering is the most common technique employed in printed interconnects. However, it is limited to substrates that can handle the high temperature requirement for sintering. For polymers …
Developing An In Vitro Validated 3d In Silico Internal Carotid Artery Sidewall Aneurysm Model, Hang Yi, Zifeng Yang, Mark Johnson, Luke Bramlage, Bryan Ludwig
Developing An In Vitro Validated 3d In Silico Internal Carotid Artery Sidewall Aneurysm Model, Hang Yi, Zifeng Yang, Mark Johnson, Luke Bramlage, Bryan Ludwig
Mechanical and Materials Engineering Faculty Publications
Introduction: Direct quantification of hemodynamic factors applied to a cerebral aneurysm (CA) remains inaccessible due to the lack of technologies to measure the flow field within an aneurysm precisely. This study aimed to develop an in vitro validated 3D in silico patient-specific internal carotid artery sidewall aneurysm (ICASA) model which can be used to investigate hemodynamic factors on the CA pathophysiology. Methods: The validated ICASA model was developed by quantifying and comparing the flow field using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations. Specifically, the flow field characteristics, i.e., blood flowrates, normalized velocity profiles, flow streamlines, …
Effects Of Pulsatile Flow Rate And Shunt Ratio In Bifurcated Distal Arteries On Hemodynamic Characteristics Involved In Two Patient-Specific Internal Carotid Artery Sidewall Aneurysms: A Numerical Study, Hang Yi, Mark Johnson, Luke C. Bramlage, Bryan Ludwig, Zifeng Yang
Effects Of Pulsatile Flow Rate And Shunt Ratio In Bifurcated Distal Arteries On Hemodynamic Characteristics Involved In Two Patient-Specific Internal Carotid Artery Sidewall Aneurysms: A Numerical Study, Hang Yi, Mark Johnson, Luke C. Bramlage, Bryan Ludwig, Zifeng Yang
Mechanical and Materials Engineering Faculty Publications
The pulsatile flow rate (PFR) in the cerebral artery system and shunt ratios in bifurcated arteries are two patient-specific parameters that may affect the hemodynamic characteristics in the pathobiology of cerebral aneurysms, which needs to be identified comprehensively. Accordingly, a systematic study was employed to study the effects of pulsatile flow rate (i.e., PFR−I, PFR−II, and PFR−III) and shunt ratio (i.e., 75:25 and 64:36) in bifurcated distal arteries, and transient cardiac pulsatile waveform on hemodynamic patterns in two internal carotid artery sidewall aneurysm models using computational fluid dynamics (CFD) modeling. Numerical results indicate that larger PFRs can cause higher wall …
New Advances In Fluid–Structure Interaction, Wenli Chen, Zifeng Yang, Gang Hu, Haiquan Jing, Junlei Wang
New Advances In Fluid–Structure Interaction, Wenli Chen, Zifeng Yang, Gang Hu, Haiquan Jing, Junlei Wang
Mechanical and Materials Engineering Faculty Publications
Fluid–structure interactions (FSI) play a crucial role in the design, construction, service and maintenance of many engineering applications, e.g., aircraft, towers, pipes, offshore platforms and long-span bridges. The old Tacoma Narrows Bridge (1940) is probably one of the most infamous examples of serious accidents due to the action of FSI. Aircraft wings and wind-turbine blades can break because of FSI-induced oscillations. To alleviate or eliminate these unfavorable effects, FSI must be dealt with in ocean, coastal, offshore and marine engineering to design safe and sustainable engineering structures. In addition, the act of wind on plants and its resultant wind-induced motions …
Influence Of Fill Percentage And Baking Parameters On The Feedability Of Metal-Cored Arc Welding Wires, Angelica Marie Black
Influence Of Fill Percentage And Baking Parameters On The Feedability Of Metal-Cored Arc Welding Wires, Angelica Marie Black
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Adequate feedability is essential for GMAW processes to ensure efficiency. The feedability of a wire refers to the wire’s ability to feed continuously through the contact tip. While there are several known causes of feedability difficulties when using cored welding wires, there are many variables that have yet to be explored thoroughly. Three factors are investigated in this research to determine their effects on feedability of cored wires: fill percentage, baking time, and baking temperature. A set of metal-cored arc welding wires were created with various fill percentages, baking times, and baking temperatures. Tension testing, microhardness testing, microstructural characterization, and …
Effect Of The Extended Rigid Flapping Trailing Edge Fringe On An S833 Airfoil, Hongtao Yu, Zifeng Yang
Effect Of The Extended Rigid Flapping Trailing Edge Fringe On An S833 Airfoil, Hongtao Yu, Zifeng Yang
Mechanical and Materials Engineering Faculty Publications
A 2D numerical simulation was conducted to investigate the effect of an extended rigid trailing edge fringe with a flapping motion on the S833 airfoil and its wake flow field, as an analogy of an owl’s wing. This study aims to characterize the influence of the extended flapping fringe on the aerodynamic performance and the wake flow characteristics downstream of the airfoil. The length (Le) and flapping frequencies (fe) of the fringe are the key parameters that dominate the impact on the airfoil and the flow field, given that the oscillation angular amplitude is fixed at 5◦. The simulation results …
Effect Of Build Geometry And Build Parameters On Microstructure, Fatigue Life, And Tensile Properties Of Additively Manufactured Alloy 718, Anna Dunn
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Additive Manufacturing (AM), particularly laser powder bed fusion, is being studied for use in critical component applications. Tensile and fatigue testing shows differences when built using different laser powers. However, when fabricated in an as-printed geometry, the gauge sections of the two specimens are different and experience different thermal behavior. This work explores microhardness, microstructure size, Niobium segregation, and porosity from samples made with varying laser power and different build geometry sizes representative of the gauge sections in the tensile and fatigue bars. Results show that microhardness varies spatially across the sample. Smaller diameter metallographic coupons (fatigue diameter) have a …
Ab Initio Methylammonium Orientation And Monolayer Effects In Hybrid Perovskite Solar Cells, Jacob M. Artz
Ab Initio Methylammonium Orientation And Monolayer Effects In Hybrid Perovskite Solar Cells, Jacob M. Artz
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Methylammonium lead triiodide (MAPbI3) has garnered attention due to their high solar cell efficiencies and low cost to manufacture, but commercialization is not yet possible owing to poor environmental stability. Thus, researchers seek ways which optimize the performance of the MAPbI3 solar cell by modifying the architecture and through interfacial engineering of the charge transport layers. Difficulties in understanding these devices arise from ion migration, charge separation and recombination, and metastable, thermally active precessions of the methylammonium (MA) moiety in the lead iodide framework. In this work, focus is given to the perovskite and an adsorbed monolayer, 2,3,4,5,6-pentafluorothiophenol (C6F5SH), which …
Ab Initio Methylammonium Orientation And Monolayer Effects In Hybrid Perovskite Solar Cells, Jacob M. Artz
Ab Initio Methylammonium Orientation And Monolayer Effects In Hybrid Perovskite Solar Cells, Jacob M. Artz
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Methylammonium lead triiodide (MAPbI3) has garnered attention due to their high solar cell efficiencies and low cost to manufacture, but commercialization is not yet possible owing to poor environmental stability. Thus, researchers seek ways which optimize the performance of the MAPbI3 solar cell by modifying the architecture and through interfacial engineering of the charge transport layers. Difficulties in understanding these devices arise from ion migration, charge separation and recombination, and metastable, thermally active precessions of the methylammonium (MA) moiety in the lead iodide framework. In this work, focus is given to the perovskite and an adsorbed monolayer, 2,3,4,5,6-pentafluorothiophenol (C6F5SH), which …
Functionalizing Ceramic Matrix Composites By The Integration Of A Metallic Substructure With Comparable Feature Size, Elizabeth Pierce Heckman
Functionalizing Ceramic Matrix Composites By The Integration Of A Metallic Substructure With Comparable Feature Size, Elizabeth Pierce Heckman
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A metallic network has been embedded in a silicon carbide fiber– silicon carbide (SiC) matrix ceramic composite (CMC) in order to combine the functional properties of the metal and the structural properties of the CMC. The processing of the composite involves iterative pre-ceramic polymer infiltration and heating to temperatures at 1100°C. The metallic structure embedded in the CMC must retain its unique properties during processing and cannot convert to a silicide or carbide resulting from diffusion of Si and C species from the SiC matrix. To gain an understanding of the diffusion process, a fully processed CMC with tungsten, tantalum, …
Fabrication And Analysis Of High-Performance Thermochemically Densified Wood, Victor Arulappan Pushparaj
Fabrication And Analysis Of High-Performance Thermochemically Densified Wood, Victor Arulappan Pushparaj
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While wood construction may be as ancient as humanity itself, wood remains one of the most utilized structural materials because of it’s availability, low cost, durability, surprisingly high specific mechanical properties, and renewability. Recent research into wood-based materials has focused on strategies for enhancing the strength and stiffness of as-grown materials. We fabricated densified wood by thermochemically treating raw white oak wood in Na2SO3 and NaOH solutions, followed by compressing the treated wood at 5MPa at high temperature. Treating the raw wood in NaOH and Na2SO3 cleaves the alpha-O-4 ether bond and beta-O-4 ether bonds, thus dissolving most of the …