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Full-Text Articles in Engineering
The Qualification Of Sealability And Creep Relaxation Of Additively Manufactured Zytel Gaskets For Pem Fuel Cells, Robert Lazarin
The Qualification Of Sealability And Creep Relaxation Of Additively Manufactured Zytel Gaskets For Pem Fuel Cells, Robert Lazarin
Open Access Theses & Dissertations
The purpose of this thesis is to study the feasibility of low-cost additive manufacturing of gaskets for proton exchange membrane fuel cells exposed to extreme temperature conditions ranging from -55°C to 100°C. With the growing popularity and decreasing costs of additive manufacturing technologies, specifically Material Extrusion (ME), research is being conducted to determine the feasibility of ME components. Thermally cycled PEMFCs may exhibit accelerated gasket deterioration, therefore, the mechanical stability of material extruded gaskets following a harsh thermal cycle must be assessed. The feasibility of the material extruded gaskets will be proven by manufacturing optimization and mechanical testing. The target …
Investigation Of Refractory High Entropy Alloys For Extreme Environment Applications, Rebecca Alexandra Romero
Investigation Of Refractory High Entropy Alloys For Extreme Environment Applications, Rebecca Alexandra Romero
Open Access Theses & Dissertations
High entropy alloys (HEAs) have emerged as an exciting class of materials with the potential for a wide range of structural, high-temperature applications. HEAs may be defined on a compositional basis as five or more principal elements in equimolar ratios. This definition led to the term âhigh entropyâ due to the high configurational entropy which is obtained with principal elements in these amounts. The combination of elements has contributed to materials that may favor solid-solution phases over intermetallic phases and have the potential to possess highly desired material properties including high yield and creep strength. The inclusion of refractory metals …
Effect Of Temperature On A Piezoelectric Mass Flow Rate Sensor Signal, Lyan Eduardo Gutierrez Hernandez
Effect Of Temperature On A Piezoelectric Mass Flow Rate Sensor Signal, Lyan Eduardo Gutierrez Hernandez
Open Access Theses & Dissertations
On this research, we are trying to demonstrate that a piezoelectric flow sensor made of PZT can produce a higher and fluctuating signal when exposed to elevated temperatures presented on the system. This type of application can be beneficial for systems that involve changes in temperature such as compressors and be able to predict certain situations presented on those systems that can be catastrophic, that is the case for surge and stall. Therefore, a system capable of going from 25â?°C-90â?°C was designed where a piezoelectric sensor was inserted at a specific location to analyze the signal produced by these changes …
Design Optimization And Optical Characterization Of A High Temperature Solar Receiver, Samia Afrin
Design Optimization And Optical Characterization Of A High Temperature Solar Receiver, Samia Afrin
Open Access Theses & Dissertations
Concentrated solar power (CSP) is a fast forwarding technology in power generation sector because of its' competitive price, abundance in nature and the most important fact is its' energy storage capability. Among the four types of available CSP technology, central receiver has more potential concerning with high temperature, power block efficiency and levelized cost of energy (LCOE). Other than conventional type of receiver design, the concept of this work is very particular in a sense of its design novelty.
National Renewable Energy Laboratory (NREL) come up with a new concept of high temperature solar receiver called near black body (NBB) …
The Effects Of Uncommon Silicides On The Oxidation Of Alloys From The Nb-Cr-Si System, Daniel Brendan Voglewede
The Effects Of Uncommon Silicides On The Oxidation Of Alloys From The Nb-Cr-Si System, Daniel Brendan Voglewede
Open Access Theses & Dissertations
Niobium based alloys are being tapped as potential successors to current nickel base superalloys in high temperature applications. In the aerospace industry, high temperature materials are constantly being pushed to higher temperature regimes in order to improve engine efficiency however current superalloys cannot be pushed further due to melting temperature limitations. Niobium, being a refractory metal, can withstand much higher temperatures than nickel however its oxidation properties are woefully inadequate.
The purpose of this study is to ascertain whether increased silicon additions can improve niobium oxidation properties by: forming ternary silicides with better oxidation properties and by preventing the formation …
Development And Characterization Of The Oxidation Behavior Of Various High Temperature Niobium Based Alloys, Benedict Isabel Portillo
Development And Characterization Of The Oxidation Behavior Of Various High Temperature Niobium Based Alloys, Benedict Isabel Portillo
Open Access Theses & Dissertations
The oxidation response of various niobium based refractory alloys from the Nb-Mo-Si-B-X alloy system has been examined at temperatures between 700 and 1400°C in air. The development of these alloys was part of an ongoing effort to develop and discover a new materials system capable of replacing nickel based super alloys. Additions of titanium were found to provide limited oxidation resistance. A discontinuous layer of TiO2 was observed to from at temperatures above 1100°C. Alloys containing titanium additions were observed to suffer from pest oxidation at low and intermediate temperatures due to the development of Nb2O5. Poor oxidation resistance at …
An Ab-Initio Study Of The Elastic Properties Of Important Group Iv Diborides At High Temperatures, Manny Gonzales
An Ab-Initio Study Of The Elastic Properties Of Important Group Iv Diborides At High Temperatures, Manny Gonzales
Open Access Theses & Dissertations
Presented is an ab-initio Molecular Dynamics (MD) study, employing the Density Functional Theory (DFT), of the lattice parameter, thermal expansion coefficients and elastic constants of ZrB2, TiB2 and HfB2 as a function of temperature. The MD trajectories provide the equilibrium lattice parameters at finite temperatures, and the gradient of the energy from these equilibrium solutions is then used to calculate the components of the stiffness tensor. The results for ZrB2 are shown to agree well with reported experimental results for the lattice parameters and elastic constants as a function of temperature.
High Temperature Oxidation Characteristics Of Nb-10w-Xcr Alloys, Maria Del Pilar Moricca
High Temperature Oxidation Characteristics Of Nb-10w-Xcr Alloys, Maria Del Pilar Moricca
Open Access Theses & Dissertations
The use of refractory metals in high temperature applications has been attractive for several years. Systems based on niobium represent a potential new generation of refractory materials systems because of their low density, high melting points, and strength at elevated temperatures. Despite these desirable characteristics, the widespread use of niobium-based alloys is limited because its oxidation resistance is still inadequate for structural applications. Understanding the oxidation kinetics of Nb-based alloys and the role of the different phases in the oxidation process is of crucial importance to improve the oxidation resistance of these materials.
The effect of Cr content on the …