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Materials Science and Engineering Faculty Research & Creative Works
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- Friction stir processing (4)
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Articles 1 - 23 of 23
Full-Text Articles in Engineering
Purification Of Solar Grade Silicon Using Electromagnetic Field, Anping Dong, Lucas N.W. Damoah, Lifeng Zhang, Hui Zhu
Purification Of Solar Grade Silicon Using Electromagnetic Field, Anping Dong, Lucas N.W. Damoah, Lifeng Zhang, Hui Zhu
Materials Science and Engineering Faculty Research & Creative Works
Non-metallic particles and the metallic impurity elements in the solar cell silicon have a strong detrimental effect on the conversion efficiency of the solar cell. Removing these impurities is one of the important tasks for silicon refining. the current paper proposed a new approach to purify silicon - electromagnetic (EM) separation. Since the non-metallic particles and the metallic impurity elements are non- or less conductive while the molten silicon is well conductive, under EM field, the Lorenz force will push the particles to the boundary layer, thus separate these inclusions. in the current study, a high frequency EM field was …
Non-Metallic Particles In Solar Grade Silicon (Sog-Si), Lucas Nana Wiredu Damoah, Anping Dong, Lifeng Zhang, Hui Zhu
Non-Metallic Particles In Solar Grade Silicon (Sog-Si), Lucas Nana Wiredu Damoah, Anping Dong, Lifeng Zhang, Hui Zhu
Materials Science and Engineering Faculty Research & Creative Works
This study investigated the non-metallic inclusions in Solar 2rade Silicon (SoG-Si), especially the distribution of inclusions in the top 15mm layer of multicrystalline silicon ingot. the SoG-Si ingot produced from directional solidification process usually pushes the impurities to the top and finally cut off and discarded, which leads to material loss. the hard inclusions lead to wire breakages during the cutting of the ingot into wafers. the main kinds of inclusions found in top-cut silicon scraps from two manufacturers have been investigated using acid extraction, automated feature analysis techniques and SEM-EDS and optical Microscope: They are needle-like Si3N4 and lumpy …
Thermal Properties Of Lunar Regolith Simulants, Kenneth W. Street, Chandra Ray, Doug Rickman, Daniel A. Scheiman
Thermal Properties Of Lunar Regolith Simulants, Kenneth W. Street, Chandra Ray, Doug Rickman, Daniel A. Scheiman
Materials Science and Engineering Faculty Research & Creative Works
Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH-, the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Thermo-Gravimetric Analysis (TGA) with Fourier Transform Infrared (FTIR) analysis provides information on …
Plasma Processing Of Lunar Regolith Simulant For Oxygen And Glass Production, S. Sen, D. Butts, J. S. O'Dell, C. S. Ray
Plasma Processing Of Lunar Regolith Simulant For Oxygen And Glass Production, S. Sen, D. Butts, J. S. O'Dell, C. S. Ray
Materials Science and Engineering Faculty Research & Creative Works
Tools for extracting life-sustaining resources from the moon are needed to support the vision for space exploration. of particular interest is the production of oxygen for life support and propulsion. on the lunar surface the only practical source for oxygen is the lunar regolith. Described in this paper is an innovative plasma reduction technique for the production of oxygen from lunar regolith. Thermodynamic calculations showed that the regolith oxides could be dissociated to yield up to 7.3 weight percent oxygen when exposed to extremely high temperatures of up to 3000°C. Subsequently the use of a plasma flame to obtain oxygen …
Effect Of Process Parameters On Abnormal Grain Growth During Friction Stir Processing Of A Cast Al Alloy, S. Jana, Rajiv S. Mishra, J. A. Baumann, G. Grant
Effect Of Process Parameters On Abnormal Grain Growth During Friction Stir Processing Of A Cast Al Alloy, S. Jana, Rajiv S. Mishra, J. A. Baumann, G. Grant
Materials Science and Engineering Faculty Research & Creative Works
The effects of process parameters and friction stir processing (FSP) run configurations on the stability of nugget microstructure at elevated temperatures were evaluated. Cast plates of an Al-7Si-0.6Mg alloy were friction stir processed using a combination of tool rotation rates and tool traverse speeds. All single pass runs showed some extent of abnormal grain growth (AGG), whereas multi-pass runs were more resistant to AGG. Additionally, higher tool rotation rate was found to be beneficial for controlling AGG. These effects were analyzed by comparing the result of this work with other published results and AGG models. © 2010 Elsevier B.V.
Microstructural Evolution During Fatigue Of Ultrafine Grained Aluminum Alloy, P. S. De, Rajiv S. Mishra
Microstructural Evolution During Fatigue Of Ultrafine Grained Aluminum Alloy, P. S. De, Rajiv S. Mishra
Materials Science and Engineering Faculty Research & Creative Works
A comparative study of the surface microstructural changes during fatigue of a precipitation hardened (PH) aluminum alloy in ultrafine grained (UFG) and microcrystalline conditions was done using orientation imaging microscopy (OIM). with increase in applied stress amplitude, the fatigue life of fine-grained PH alloy deteriorated. on the other hand, at lower stress amplitudes an improvement in fatigue life was noted. This trend was reversed for the coarse-grained PH alloy. in UFG alloy, the fatigue life improved at all stress amplitudes. the variation in fatigue life response between coarse, fine and ultrafine grain PH alloy was due to the increased interaction …
Thermodynamics Of Strained Vanadium Dioxide Single Crystals, Yijia Gu, Jinbo Cao, Junqiao Wu, Long-Qing Chen
Thermodynamics Of Strained Vanadium Dioxide Single Crystals, Yijia Gu, Jinbo Cao, Junqiao Wu, Long-Qing Chen
Materials Science and Engineering Faculty Research & Creative Works
Vanadium dioxide undergoes a metal-insulator transition, in which the strain condition plays an important role. To investigate the strain contribution, a phenomenological thermodynamic potential for the vanadium dioxide single crystal was constructed. The transformations under the uniaxial stress, wire, and thin film boundary conditions were analyzed, and the corresponding phase diagrams were constructed. The calculated phase diagrams agree well with existing experimental data, and show that the transformation temperature (and Curie temperature) strongly depends on the strain condition.
Analysis Of Microstructural Evolution During Friction Stir Welding Of Ultrahigh-Strength Steel, M. Ghosh, K. Kumar, R. S. Mishra
Analysis Of Microstructural Evolution During Friction Stir Welding Of Ultrahigh-Strength Steel, M. Ghosh, K. Kumar, R. S. Mishra
Materials Science and Engineering Faculty Research & Creative Works
Friction stirs lap-welded advanced high-strength M190 steel exhibited formation of lath martensite at weld nuggets, a ferrite layer at faying surfaces and a ferrite-pearlite microstructure at the bottom of the stir zone. the phase transformation was governed by severe plastic deformation in the austenitic region followed by cooling. the strain rate and peak temperature played key roles in controlling the prior-austenitic grain size and were correlated to the Zener-Hollomon parameter. an empirical relationship has been obtained for dynamically recrystallized austenite grains. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Effect Of Friction Stir Processing On Microstructure And Tensile Properties Of An Investment Cast Al-7si-0.6mg Alloy, Saumyadeep Jana, Rajiv S. Mishra, John A. Baumann, Glenn J. Grant
Effect Of Friction Stir Processing On Microstructure And Tensile Properties Of An Investment Cast Al-7si-0.6mg Alloy, Saumyadeep Jana, Rajiv S. Mishra, John A. Baumann, Glenn J. Grant
Materials Science and Engineering Faculty Research & Creative Works
Friction stir processing (FSP) is emerging as a promising tool for microstructural modification. the current study assesses the effects of FSP on the microstructure and mechanical properties of an investment cast Al-7Si-Mg alloy. FSP eliminates porosity and significantly refines eutectic Si particles. the extent of particle refinement varied with changes in processing conditions. a high tool rotation rate and a low-to-intermediate tool traverse speed generated a higher volume fraction of finer particles. Tensile ductility changed significantly as a result of FSP, whereas ultimate tensile strength improved only marginally. Yield strength was similar in both cast and FSP samples under various …
Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Tieshu Huang, Nikhil D. Doiphode, M. N. Rahaman, Ming-Chuan Leu, B. Sonny Bal, D. E. Day
Freeze Extrusion Fabrication Of 13-93 Bioactive Glass Scaffolds For Bone Repair, Tieshu Huang, Nikhil D. Doiphode, M. N. Rahaman, Ming-Chuan Leu, B. Sonny Bal, D. E. Day
Materials Science and Engineering Faculty Research & Creative Works
There is an increasing demand for synthetic scaffolds with the requisite biocompatibility, internal architecture, and mechanical properties for the bone repair and regeneration. In this work, scaffolds of a silicate bioactive glass (13-93) were prepared by a freeze extrusion fabrication (FEF) method and evaluated in vitro for potential applications in bone repair and regeneration. The process parameters for FEF production of scaffolds with the requisite microstructural characteristics, as well as the mechanical and cell culture response of the scaffolds were evaluated. After binder burnout and sintering (60 min at 700°C), the scaffolds consisted of a dense glass network with interpenetrating …
Processing And Characterization Of New Oxy-Sulfo-Telluride Glasses In The Ge-Sb-Te-S-O System, C. (Charmayne) Smith (Lonergan), J. Jackson, L. Petit, C. Rivero-Baleine, K. Richardson
Processing And Characterization Of New Oxy-Sulfo-Telluride Glasses In The Ge-Sb-Te-S-O System, C. (Charmayne) Smith (Lonergan), J. Jackson, L. Petit, C. Rivero-Baleine, K. Richardson
Materials Science and Engineering Faculty Research & Creative Works
New oxy-sulfo-telluride glasses have been prepared in the GeSbTeSO system employing a two-step melting process which involves the processing of a chalcogenide glass (ChG) and subsequent melting with TeO2 or Sb2O3. The progressive incorporation of O at the expense of S was found to increase the density and the glass transition temperature and to decrease the molar volume of the investigated oxy-sulfo-telluride glasses. We also observed a shift of the visNIR cut-off wavelength to longer wavelength probably due to changes in Sb coordination within the glass matrix and overall matrix polarizability. Using Raman spectroscopy, correlations …
Removal Of Inclusions From Aluminum Through Filtration, Lucas Nana Wiredu Damoah, Lifeng Zhang
Removal Of Inclusions From Aluminum Through Filtration, Lucas Nana Wiredu Damoah, Lifeng Zhang
Materials Science and Engineering Faculty Research & Creative Works
Filtration experiments were carried out using both an AlF3 slurry-coated and an uncoated Al2O3 ceramic foam filter to study the removal of nonmetallic inclusions and impurity elements. the results showed that the 30-ppi ceramic foam filter removed up to 85 pct inclusions from aluminum. Several pictures of two- and three-dimensional morphologies of both nonmetallic and intermetallic inclusions also have been presented. the following contributing mechanisms for the removal of nonmetallic inclusions in the deep-bed filtration mode are proposed: (1) collision with walls and interception effect and (2) the formation of both intermetallic and nonmetallic inclusion bridges during filtration. Fluid dynamics …
Room-Temperature Protonic Conduction In Nanocrystalline Films Of Yttria-Stabilized Zirconia, Hugo J. Avila-Paredes, Enrique Barrera-Calva, Harlan U. Anderson, Roger A. De Souza, Manfred Martin, Zuhair A. Munir, Sangtae Kim
Room-Temperature Protonic Conduction In Nanocrystalline Films Of Yttria-Stabilized Zirconia, Hugo J. Avila-Paredes, Enrique Barrera-Calva, Harlan U. Anderson, Roger A. De Souza, Manfred Martin, Zuhair A. Munir, Sangtae Kim
Materials Science and Engineering Faculty Research & Creative Works
We report the results of our investigation on protonic conduction in 1 µm-thick polycrystalline films of 8 mol% yttria-stabilized zirconia (YSZ) with an average grain size of 17 nm prepared on sapphire substrate using a spin-coating process. Protonic conductivity of the films is found to be higher by over an order of magnitude (at 30 °C) than earlier reported values for nanocrystalline YSZ bulk ceramics with a similar grain size. This value is comparable to the oxygen-ionic conductivity of this material presented at about 400 °C. These results suggest that, besides grain size, the structural characteristics of the grain boundaries …
Investigation Of Creep Threshold Stresses Using In Situ Tem Straining Experiment In An Al-5y2o3-10sic Composite, S. P. Deshmukh, Rajiv S. Mishra, I. M. Robertson
Investigation Of Creep Threshold Stresses Using In Situ Tem Straining Experiment In An Al-5y2o3-10sic Composite, S. P. Deshmukh, Rajiv S. Mishra, I. M. Robertson
Materials Science and Engineering Faculty Research & Creative Works
Creep behavior of metal matrix composites is similar to dispersion strengthen alloys and characterized by the presence of a threshold stress below which the creep rate is negligible. This threshold stress is attributed, at least in dispersion-strengthened alloys, to dislocation particle interactions in which the detachment of the dislocations from the particle is the rate-limiting step. Creep experiments were performed on an Al-5Y2O3-10SiC composite in the temperature range of 473 and 573 K and the nature of the dislocation-particle interaction was determined by performing in situ straining experiments at elevated temperature in a transmission electron microscope. …
The Strength Of Silicate Glasses: What Do We Know, What Do We Need To Know?, Charles R. Kurkjian, Prabhat K. Gupta, Richard K. Brow
The Strength Of Silicate Glasses: What Do We Know, What Do We Need To Know?, Charles R. Kurkjian, Prabhat K. Gupta, Richard K. Brow
Materials Science and Engineering Faculty Research & Creative Works
In the last few years, there has been increased interest in methods to improve the practical strength of inorganic glasses. during this same time period, new theoretical and experimental techniques have appeared. in this paper, we discuss this interest and indicate how and where these new techniques may help us to achieve our objective to increase the practical strength of glass. Our ability to measure the intrinsic inert strength of glass fibers as well as the development of stresses around indentations and scratches now allows us to attack these two important issues experimentally. Likewise, major advances have been made in …
Functionally Graded Materials By Laser Metal Deposition (Preprint), Syamala R. Pulugurtha, Joseph William Newkirk, Frank W. Liou, Hsin-Nan Chou
Functionally Graded Materials By Laser Metal Deposition (Preprint), Syamala R. Pulugurtha, Joseph William Newkirk, Frank W. Liou, Hsin-Nan Chou
Materials Science and Engineering Faculty Research & Creative Works
Fabrication of functionally graded materials (FGMs) by laser metal deposition (LMD) has the potential to offer solutions to key engineering problems over the traditional metalworking techniques. But the issues that need to be addressed while building FGMs are intermixing in the layers and cracking due to the residual stresses. This paper is to present the study of the effect of process parameters (laser power and travel speed) on the degree of dilution between the substrate (or, previous layer) and powder material for few metallurgical systems.
Effect Of Friction Stir Processing On Fatigue Behavior Of An Investment Cast Al-7si-0.6 Mg Alloy, S. Jana, Rajiv S. Mishra, J. B. Baumann, G. Grant
Effect Of Friction Stir Processing On Fatigue Behavior Of An Investment Cast Al-7si-0.6 Mg Alloy, S. Jana, Rajiv S. Mishra, J. B. Baumann, G. Grant
Materials Science and Engineering Faculty Research & Creative Works
Cast aluminum alloys in general show poor fatigue performance due to the presence of defects. Friction stir processing (FSP) can be used as a tool to enhance the mechanical properties of cast alloys by eliminating such defects. in the present study FSP led to a five times improvement in fatigue life of an investment cast Al-7Si-0.6 Mg hypoeutectic alloy. the reason for such an enhancement was linked to the closure of casting porosities, which acted as crack nucleation sites in the as cast condition. Porosities acted as notches in the as cast alloy and led to an order of magnitude …
Reaction Sintered Zirconium Carbide/Tungsten Composite Bodies And A Method For Producing The Same, Shi C. Zhang, Greg Hilmas, William Fahrenholtz
Reaction Sintered Zirconium Carbide/Tungsten Composite Bodies And A Method For Producing The Same, Shi C. Zhang, Greg Hilmas, William Fahrenholtz
Materials Science and Engineering Faculty Research & Creative Works
A method of sintering a composite body characterized by a transition metal carbide phase (such as a ZrC phase) substantially evenly distributed in a second, typically refractory, transition metal (such as W) matrix at ambient pressures, including blending a first predetermined amount of first transition metal oxide powder (such as ZrO2) with a second predetermined amount of second transition metal carbide powder (such as WC powder). Next the blended powders are mixed to yield a substantially homogeneous powder mixture and a portion of the substantially homogeneous powder mixture is formed into a green body. The body is fired …
An Analysis Of Strength And Ductility Of Ultrafine Grained Al Alloys, R. Kapoor, P. S. De, R. S. Mishra
An Analysis Of Strength And Ductility Of Ultrafine Grained Al Alloys, R. Kapoor, P. S. De, R. S. Mishra
Materials Science and Engineering Faculty Research & Creative Works
This paper brings together and compares data of various ultrafine grained (UFG) Al alloys processed through different routes. in general, the trend of decreasing ductility with increasing strength was observed for the UFG alloys. as compared to the coarse grained (CG) alloys, the UFG alloys show a lower ductility, a lower extent of work-hardening and a lower uniform elongation. Unlike the CG alloys, which show a large fraction of uniform to total elongation, in UFG alloys this fraction varies with processing technique. It is shown here that aging of some UFG Al alloys improves ductility. Further, it is shown that …
Influence Of Fraction Of High Angle Boundaries On The Mechanical Behavior Of An Ultrafine Grained Al-Mg Alloy, R. Kapoor, N. Kumar, R. S. Mishra, C. S. Huskamp, K. K. Sankaran
Influence Of Fraction Of High Angle Boundaries On The Mechanical Behavior Of An Ultrafine Grained Al-Mg Alloy, R. Kapoor, N. Kumar, R. S. Mishra, C. S. Huskamp, K. K. Sankaran
Materials Science and Engineering Faculty Research & Creative Works
The mechanical behavior of ultrafine grained AA5052 processed through different techniques-rolled, annealed, friction stir processed (FSP) and equal channel angular pressed (ECAP)-were compared and correlated with microstructure. the microstructure was characterized using electron back scattered diffraction to obtain the boundary spacing, the fraction of high angle boundaries and to estimate the dislocation density from local misorientations. Both FSP and ECAP conditions had ultrafine boundary spacing, but the fraction of high angle boundaries was larger for the FSP condition. Tensile deformation carried out at 297K, and 10-3s-1 showed a lower work-hardening rate and recovery rate for FSP as compared to the …
Friction Stir Processing Of Commercial Grade Marine Alloys To Enable Superplastic Forming, Christopher B. Smith, Arun Mohan, Rajiv S. Mishra, Murray Mahoney, Mike Miles, Scott M. Gillis, Lee M. Cerveny, Gerald Opichka
Friction Stir Processing Of Commercial Grade Marine Alloys To Enable Superplastic Forming, Christopher B. Smith, Arun Mohan, Rajiv S. Mishra, Murray Mahoney, Mike Miles, Scott M. Gillis, Lee M. Cerveny, Gerald Opichka
Materials Science and Engineering Faculty Research & Creative Works
The use of friction stir processing (FSP) on marine grade aluminum sheet has been investigated with the objective of locally enhancing the material properties. This can potentially allow low-cost commercial grade aluminum to be used in superplastic forming applications or further enhance the formability to allow more complex geometries to be formed. FSP has been demonstrated to enable super plasticity (uniform elongations >250%) in 5083-H116 over a range of friction stir processing conditions. © (2010) Trans Tech Publications.
Impedance Spectroscopy Of Batio₃ Cubes Suspended In Lossy Liquids As A Physical Model Of Two-Phase System, Piotr Z. Jasinski, Vladimir Petrovsky, Fatih Dogan
Impedance Spectroscopy Of Batio₃ Cubes Suspended In Lossy Liquids As A Physical Model Of Two-Phase System, Piotr Z. Jasinski, Vladimir Petrovsky, Fatih Dogan
Materials Science and Engineering Faculty Research & Creative Works
Impedance spectroscopy techniques were used for analysis of the physical model in a two-phase system toward determining of dielectric constant of dielectric particles suspended in liquids at various solids loading (volume fraction) levels. Model experimental studies were conducted using BaTiO3 as a dielectric material that was prepared as small cubes of uniform size (2×2×1 mm). Barium titanate (BT) cubes having a dielectric constant of 3850 were immersed in liquids of low dielectric constant and moderate electrical conductivity. Measured impedance spectra consisted of two semicircles, which were fitted for (R∥C)(R∥C) equivalent circuit. The parameters obtained from fitting were compared with the …
Effect Of Phosphorus On Cleavage Fracture In Κ-Carbide, N. I. Medvedeva, Ryan A. Howell, David C. Van Aken, Julia E. Medvedeva
Effect Of Phosphorus On Cleavage Fracture In Κ-Carbide, N. I. Medvedeva, Ryan A. Howell, David C. Van Aken, Julia E. Medvedeva
Materials Science and Engineering Faculty Research & Creative Works
To understand the origin of cleavage fracture which dominates in Fe(Mn)-Al-C alloys at a high phosphorus concentration, we performed first-principles study of the phosphorus effect on ideal cleavage energy and critical stress in κ-carbide, Fe3 AlC, a precipitate in the austenitic alloys. We find that phosphorus has higher solubility in Fe3 AlC than in γ-Fe and sharply reduces the cleavage characteristics of κ-carbide. We show that strong anisotropy of the Fe-P bonds in Fe3 (Al,P) C under tensile stress, leads to the appearance of large structural voids and may facilitate crack nucleation.