905 Matching Results

Search Results

Advanced search parameters have been applied.

Plastic Magnesia

Description: Report issued by the Bureau of Mines over the production methods and uses of plastic magnesia. Methods, properties, and uses of plastic magnesia are discussed. This report includes tables, illustrations, and photographs.
Date: 1925
Creator: Ralston, Oliver C. & Pike, Robert D.
Partner: UNT Libraries Government Documents Department

Interfacial structures and energetics of the strengthening precipitate phase in creep-resistant Mg-Nd-based alloys

Description: This article discusses the study of two interfaces– {112}β1/{1100}Mg and {111}β1/{1120}Mg– that are commensurate with β1/hcp-Mg orientation relationship via first principles calculations.
Date: January 17, 2017
Creator: Choudhuri, Deep; Banerjee, Rajarshi & Srivilliputhur, Srinivasan
Partner: UNT College of Engineering

Some effects of heat transfer at Mach number 2.0 at stagnation temperatures between 2,310 and 3,500 degrees R on a magnesium fin with several leading-edge modifications

Description: Report presenting testing of four models of a thin magnesium fin, with the leading edge swept back 35 degrees, of a type used to stabilize the first stages of rocket-propelled multistage hypersonic models. The investigation was carried out to determine some effects of aerodynamic heating at high stagnation temperatures on the leading edges of fins and to determine the relative effectiveness of several leading-edge protective methods. The fins tested included a basic fin, a fin with a blunt leading edge, a fin with a blunt leading edge wrapped with Inconel, and a fin with a blunt leading edge made of stainless steel.
Date: April 18, 1957
Creator: Bland, William M., Jr. & Bressette, Walter E.
Partner: UNT Libraries Government Documents Department

PROPERTIES AND HANDLING PRACTICES FOR MAGNESIUM: A LITERATURE SURVEY

Description: A survey of Mg including the cost and availability of various high- purity grades, safe handling considerations, methods of distillation and production physical and thermodynamic properties, and the binary and ternary alloys is presented. A bibliography is included with 157 references. (J.R.D.)
Date: March 1, 1958
Creator: Breederman, M.; Bennett, G.A.; Burris, L. Jr.; Dillon, I.G.; Winsch, I.O.; Nathans, M.W. et al.
Partner: UNT Libraries Government Documents Department

Laser beam welding of AZ31B-H24 magnesium alloy.

Description: The laser beam weldability of AZ31B magnesium alloy was examined with high power CW CO{sub 2} and pulsed Nd:YAG lasers. The low viscosity and surface tension of the melt pool make magnesium more difficult to weld than steel. Welding parameters necessary to obtain good welds were determined for both CW CO{sub 2} and pulsed Nd:YAG lasers. The weldability of the magnesium alloy was significantly better with the Nd:YAG laser. The cause of this improvement was attributed to the higher absorption of the Nd:YAG beam. A lower threshold beam irradiance was required for welding, and a more stable weldpool was obtained.
Date: September 29, 1998
Creator: Leong, K. H.
Partner: UNT Libraries Government Documents Department

In-situ white beam microdiffraction study of the deformation behavior in polycrystalline magnesium alloy during uniaxial loading

Description: Scanning white beam X-ray microdiffraction has been used to study the heterogeneous grain deformation in a polycrystalline Mg alloy (MgAZ31). The high spatial resolution achieved on beamline 7.3.3 at the Advanced Light Source provides a unique method to measure the elastic strain and orientation of single grains as a function of applied load. To carry out in-situmeasurements a light weight (~;;0.5kg) tensile stage, capable of providing uniaxial loads of up to 600kg, was designed to collect diffraction data on the loading and unloading cycle. In-situ observation of the deformation process provides insight about the crystallographic deformation mode via twinning and dislocation slip.
Date: January 19, 2007
Creator: Source, Advanced Light; Tamura, Nobumichi; Lynch, P.A.; Stevenson, A.W.; Liang, D.; Parry, D. et al.
Partner: UNT Libraries Government Documents Department

Use of MgO to mitigate the effect of microbial CO{sub 2} production in the Waste Isolation Pilot Plant

Description: The Waste Isolation Pilot Plant (WIPP), located in a salt bed in southern New Mexico, is designed by US Department of Energy to demonstrate the safe and permanent disposal of design-basis transuranic waste. WIPP performance assessment requires consideration of radionuclide release in brines in the event of inadvertent human intrusion. The mobility of radionuclides depends on chemical factors such as brine pmH (-log molality of H{sup +}) and CO{sub 2} fugacity. According to current waste inventory estimates, a large quantity ({approximately} 10{sup 9} moles C) of organic materials will be emplaced in the WIPP. Those organic material will potentially be degraded by halophilic or halotolerant microorganisms in the presence of liquid water in the repository, especially if a large volume of brine is introduced into the repository by human intrusions. Organic material biodegradation will produce a large amount of CO{sub 2}, which will acidify the WIPP brine and thus significantly increase the mobility of actinides. This communication addresses (1) the rate of organic material biodegradation and the quantity of CO{sub 2} to be possibly generated, (2) the effect of microbial CO{sub 2} production on overall WIPP performance, and (3) the mechanism of using MgO to mitigate this effect.
Date: January 29, 1997
Creator: Wang, Y.; Brush, L.H. & Bynum, R.V.
Partner: UNT Libraries Government Documents Department

Conversion of light hydrocarbon gases to metal carbides for production of liquid fuels and chemicals. Quarterly technical status report, April 1, 1995--June 30, 1995

Description: Upgrading of the experimental apparatus was necessitated by problems encountered in the previous scoping runs with CH{sub 4}/MgO. To further improve plasma stability, a pressure controller was installed on the cooling chamber to maintain the chamber pressure constant at 1 atm and a mass flow controller was installed on the main plasma gas inlet line. With a fully functional data acquisition and control system, there is now the capability to record arc voltage, arc current, chamber pressure, feed gas mass flow, and cooling water and gas temperatures during the relatively short experimental runs. With this system, an improved sampling protocol can also be implemented whereby gas and solid sampling are initiated only when fully developed flowrates of methane and MgO are established in the plasma. Solid products from a scoping run under conditions of excess MgO above the stoichiometric requirement for 100% conversion of the methane exhibited intense reactivity in the open atmosphere, indicating high concentrations of magnesium carbide in the product. The hypothesis is that reaction begins with hydrolysis of the carbide by atmospheric moisture giving acetylene and/or methylacetylene which then, because of the intense local heating (possibly due to the fine particle sizes of the recently formed carbides), are ignited to produce flaming combustion.
Date: August 1, 1995
Creator: Diaz, A.F.; Modestino, A.J. & Howard, J.B.
Partner: UNT Libraries Government Documents Department

Microstructure for Enhanced Plasticity and Toughness

Description: Magnesium is the lightest metal with a very high specific strength. However, its practical applicability is limited by its toughness and reliability. Mg, being HCP has low ductility. This makes the improvement of toughness a grand challenge in Mg alloys. Friction stir processing (FSP) is a thermomechanical technique used to effect microstructural modification. Here, FSP was utilized to affect the toughness of WE43 sheets through microstructural modification. Room temperature Kahn-type tests were conducted to measure the toughness of WE43 sheets. Microscopic techniques (SEM, TEM) was utilized to study the effect of various microstructural factors like grain size, texture, constituent particles, precipitates on crack initiation and propagation. Tensile properties were evaluated by mini-tensile tests. Crack growth in WE43 sheets was also affected by mechanics and digital image correlation (DIC) was utilized to study the plastic zone size. The underlying mechanisms affecting toughness of these sheets were understood which will help in formulating ways in improving it. WE43 nanocomposites were fabricated via FSP. Uniform distribution of reinforcements was obtained in the composites. Improved mechanical properties like that of enhanced strength, increased hardness and stiffness were obtained. But contrary to other metal matrix composites which show reduction in ductility with incorporation of ceramic reinforcements, the nanocomposites showed good strength-ductility combination. The composites were precisely characterized and mechanisms governing this property were studied. The nano-length of the reinforcements was observed to be the main criteria and the dislocation-particle interaction, the main reason behind the strength-ductility property.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: August 2016
Creator: Das, Shamiparna
Partner: UNT Libraries

Dissimilar Friction Stir Welding Between Magnesium and Aluminum Alloys

Description: Joining two dissimilar metals, specifically Mg and Al alloys, using conventional welding techniques is extraordinarily challenging. Even when these alloys are able to be joined, the weld is littered with defects such as cracks, cavities, and wormholes. The focus of this project was to use friction stir welding to create a defect-free joint between Al 2139 and Mg WE43. The stir tool used in this project, made of H13 tool steel, is of fixed design. The design included an 11 mm scrolled and concave shoulder in addition to a 6 mm length pin comprised of two tapering, threaded re-entrant flutes that promoted and amplified material flow. Upon completion of this project an improved experimental setup process was created as well as successful welds between the two alloys. These successful joints, albeit containing defects, lead to the conclusion that the tool used in project was ill fit to join the Al and Mg alloy plates. This was primarily due to its conical shaped pin instead of the more traditional cylindrical shaped pins. As a result of this aggressive pin design, there was a lack of heat generation towards the bottom of the pin even at higher (800-1000 rpm) rotation speeds. This lack of heat generation prohibited the material from reaching plastic deformation thus preventing the needed material flow to form the defect free joint.
Date: December 2016
Creator: Reese, Gregory A
Partner: UNT Libraries

Possibility of MGB2 application to superconducting cavities

Description: A metallic superconductor, magnesium diboride (MgB{sub 2}), which has a transition temperature of {approx}39 K, was discovered in early 2001. Published data taken at 10 GHz demonstrate that the material has a surface resistance comparable to niobium. This paper discusses the possibility of MgB{sub 2} as compared to Nb and Nb{sub 3}Sn. Also, a possible method of fabricating a MgB{sub 2} cavity using the hot isostatic press (HIP) technique is proposed.
Date: January 1, 2002
Creator: Tajima, T. (Tsuyoshi)
Partner: UNT Libraries Government Documents Department

THE REACTIONS OF MAGNESIUM AND MAGNESIUM ALLOYS WITH GASES AT HIGH TEMPERATURES

Description: The ignition temperature of Mg is influenced by numerous variables of which the most important appear to be alloying (or dissimilar metal contact) and the concentration of the Mg vapor over the heated metal. Most alloying elements lower the ignition temperature; however, Re additions inhibit the pyrophoricity of alloys up to temperatures in excess of their melting point. Although there is evidence that the ignition temperature of Mg is O/sub 2/-pressure sensitive, its effects are slight in comparison to the above factors. Similarly, the changes observed in the ignition temperature resulting from changing the corrosive gas to CO/sub 2/ and SO/sub 3/ are slight. The corrosion products resulting from decomposition of these gases are MgO and C for atmospheres composed of CO/sub 2/, air, and 0/sub 2/, and MgSO/sub 4/ in the case of SO/sub 2/ atmospheres. Moisture in the above gases accelerates the corrosion rate. In CO/sub 2/, the rate is increased by moisture by a factor of 4 in one month to a factor of 2 after two months. There is no information on the effect of moisture on the ignition temperature; however, if the correlation between oxidation rates and ignition temperatures is still valid, it is expected that moisture will lower the ignition temperature. For fuel elements of U canned in Mg, it is believed that the real hazard in case of a can failure due to excessive temperature is the pyrophoricity of U, which ignites at 350 deg C in air. (auth)
Date: January 20, 1958
Creator: Inouye, H.
Partner: UNT Libraries Government Documents Department

PERFORMANCE OF CHIPPED MAGNESIUM VERSUS HAMMERMILLED MAGNESIUM IN THE BOMB REDUCTION OF TETRAFLUORIDE. PART I

Description: The O. Hommel Company, of Carnegie, Penna., supplied Mallinckrodt Chemical Works with three types of Mg chips or powder (Type 84, 85B, and 87B) formed by machining Mg ingots. This material was tested and compared with standard New England Lime Mg in a series of reduction runs. A new type of powder (Type 93) developed by the O. Hommel Company during the course of the first experiment was also sert to Mallinckrodt Chemical Works foi preliminary testing. As this was superior to the other tynes tested, a large batch was made up and sent to both Electro Metallurgical Company and Mallinckrodt Chemical Works in order to confirm the preliminary results obtained by Mallinckrodt Chemical Works alone. (auth)
Date: June 1, 1945
Partner: UNT Libraries Government Documents Department

Processing of Special Metal for Hanford

Description: The object of this project is to reduce the impurities and raise the density of rejected slugs and briquetted turnings from these slugs by recasting the material. Summary and conclusions are (1) slugs and briquettes made from turnings produced when these slugs were machined can be recast with great improvement in quality; (2) casting this material is quite hard on graphite crucibles, but a long-range program might point the way to better graphite usage; (3) this metal run alone gives fair yields (88.8% to 94.8%) if heated to 2500 F and then cooled to 2400 F before pouring. Mixing with virgin metal improves the final quality, but does not materially increase the yield; (4) briquettes should not be mixed with magnesium before recasting.
Date: March 10, 1947
Creator: Oppold, William A.
Partner: UNT Libraries Government Documents Department

The Effects of Externally Solidified Product on Wave Celerity and Quality of Die Cast Products

Description: The cold chamber die casting process is used to produce essentially all the die cast aluminum products and about 50% of the die cast magnesium products made today. Modeling of the cold chamber die casting process and metallographic observations of cold chamber die cast products indicate that typically 5 to 20% of the shot weight is solidified in the shot sleeve before or during cavity filling. The protion of the resulting die casting which is solidified in the shot sleeve is referred to as externally solidified product, or, when identified as a casting defect, as cold flakes. This project was directed to extending the understanding of the effects of externally solidified product on the cold chamber die casting process and products to enable the production of defect-free die castings and reduce the energy associated with these products. The projected energy savings from controlling the fraction of externally solidified product in die cast components is 40 x 10 Btu through the year 2025.
Date: October 10, 2003
Creator: Mobley, Carroll; Sahai, Yogeshwar & Brevick, Jerry
Partner: UNT Libraries Government Documents Department

Analysis of the potential for new automotive uses of magnesium

Description: This paper describes the scope of a new project, just initiated, for the Lightweight Materials Program within the Office of Transportation Materials. The Center for Transportation Research and the Energy Technology Division at Argonne National Laboratory will assess the feasibility and technical potential of using magnesium and its alloys in place of steel or aluminum for automotive structural and sheet applications in order to enable more energy-efficient, lightweight passenger vehicles. The analysis will provide an information base to help guide magnesium research and development in the most promising directions.
Date: December 31, 1994
Creator: Stodolsky, F.; Gaines, L.; Cuenca, R. & Wu, S.
Partner: UNT Libraries Government Documents Department