Browse Topic: Powder metallurgy

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Light Weight Aluminum Composite Bearing Liners for Vertical LiftF-0081-2025-02405/20/2025
Gamma Alloys manufactures aluminum matrix composite bearing liners for helicopter transmissions that have the performance of steel liners at one third the weight. These bearing liners have diameters between 2.5 and 24 inches. Our composites are made by blending aluminum powders with spheroidized alumina particles. These powders are then vacuum hot pressed into billets. These billets are then extruded into shapes that can be machined into bearing liners. The extrusion process transforms the powder metallurgy product into a wrought product. Over 2000 liners have been made and are currently flying in R&D vehicles since 2018 with no maintenance issues.
Harrigan, William, Peabody, Micah, Zhang, Yuzheng
Aluminum Alloy Powder 7.0Si - 0.55Mg - 0.12TiAMS7020 (Current)11/9/2021
This specification covers an aluminum alloy in the form of pre-alloyed powder.
AMS AM Additive Manufacturing Metals
Metal Powder Feedstock Size ClassificationsAMS7025 (Current)4/22/2021
This specification covers particle size classifications and corresponding particle size distribution requirements for metal powder feedstock conforming to a classification.
AMS AM Additive Manufacturing Metals
Tungsten Carbide-Cobalt Chrome Powder Agglomerated and SinteredAMS7882C (Historical)4/21/2020
This specification covers tungsten carbide-cobalt chrome in the form of powder.
AMS F Corrosion Heat Resistant Alloys Committee
Tungsten Carbide-Cobalt PowderAMS7879G (Current)4/21/2020
This specification covers tungsten carbide-cobalt in the form of powder.
AMS F Corrosion Heat Resistant Alloys Committee
Study on Effect of Laser Peening on Inconel 718 Produced by DMLS Technique *CSP Meta Testing 2*2019-28-014610/11/2019
In Additive manufacturing, Direct Metal Laser Sintering (DMLS) is a rapid manufacturing technique used for manufacturing of functional component. Finely powered metal is melted by using high-energy fiber laser, by Island principle strategy that produces mechanically and thermally stable metallic component with reduced stresses, thermal gradients and at high precision. Inconel is an austenitic chromium nickel-based superalloy often used in the applications which require high strength and temperature resistant. It can retain its properties at high temperature. An attempt is made to examine the effect of laser shot peening (LSP) on DMLS Inconel 718 sample. Microstructure shows elliptical shaped structure and formation of new grain boundaries. The surface roughness of the material has been increased due to the effect of laser shock pulse and ablative nature. Macro hardness increased to 13% on the surface. Depth wise microhardness was investigated, found to be 17% increase on the sub-layer of the material due to the effect of a hardened matrix formed by precipitation hardening and grain size refinement attributed by laser shock peening. SEM analysis shows larger grains are being refined into smaller grains. The residual stress analysis result shows compressive residual stress values have increased.
Navin Kumar, Nattudurai, Yadav, Aditya Chandrakant, Raja, Kumar, Prabhakaran, Subramanian, Naiju, Chooriyaparambil Damodaran, Kalainathan, Sivaperuman
The Future of 3D Printing: From Prototyping to ProductionTBMG-3537010/1/2019
Additive manufacturing, better known as 3D printing, has been evolving for the last 30 years. Now it’s set to enter the mainstream, and evolving technology including new printers and 3D printed metals have the potential to transform manufacturing and logistics across multiple sectors.
Contaminant-Free SteelTBMG-336081/1/2019
For many highly stressed engineering applications like bearings and gears, contaminated steel parts can lead to devastating outcomes such as an emergency shutdown or the end of a mission. Ensuring that these critical components are as homogeneous as possible and free from porosity and other flaws is vital to performance, yet conventional steelmaking processes have multiple pathways of entry for unwanted contamination.
MIM and 3D Printing: Precision Cleaning and Product Finishing of Medical DevicesTBMG-3325111/1/2018
As the miniaturization trend continues to take the medical device world by storm, manufacturing with metal injection molding (MIM) and additive processes such as 3D printing are gaining widespread acceptance, allowing designers more options for creating parts economically that would otherwise be impossible to manufacture. In many instances, these state-of-the-art MIM and 3D printed processes are not possible without the use of special cleaning and or solvent-based process treatments.
Nickel Alloy, Corrosion and Heat-Resistant, Powder for Additive Manufacturing, 62Ni - 21.5Cr - 9.0Mo - 3.65NbAMS7001 (Current)6/8/2018
This specification covers a corrosion and heat-resistant nickel alloy in the form of pre-alloyed powder.
AMS AM Additive Manufacturing Metals
Process Requirements for Production of Metal Powder Feedstock for Use in Additive Manufacturing of Aerospace PartsAMS7002 (Historical)6/8/2018
This specification is to prescribe process requirements for production of metal powder feedstock for use in additive manufacturing of aerospace parts.
AMS AM Additive Manufacturing Metals
Transmission-Mounted Power Control Unit Including 12-Volt DC-DC Converter for Two-Motor Hybrid System2018-01-04574/3/2018
This research proposes a third-generation power control unit (PCU) for a two-motor hybrid system. To make a more compact intelligent power unit (IPU) to be located under the second seat, a PCU with a 12-volt DC-DC converter (DCDC) that mounts directly on the transmission was developed, whereas the DCDC was previously mounted within the IPU. Since this has a considerable impact on the engine room layout, the technology described below was used to make the PCU even more compact than the second-generation unit. The power module, a key component of the PCU, now uses Ag nanoparticles sintering bonding rather than conventional solder bonding. This helps lower thermal resistance and enables smaller power semiconductors. The voltage control unit (VCU) has a new circuit that uses a multi-stage switching circuit and electric power transfer capacitor instead of the conventional chopper circuit. This makes it possible to shrink the reactor to less than 65% of its usual volume without raising the carrier frequency, and enables a layout that efficiently uses both sides of the water jacket (W/J), so that no specially designed W/J needs to be added just for the DCDC. As for the W/J seal, friction stir welding (FSW) to increase rigidity was used to reduce seal width and to make the W/J itself more compact. The use of these compactness technologies enabled the PCU to maintain all the efficiency of a second-generation PCU and made it possible to build the DCDC in the PCU with its volume less than a second-generation one. Development of this PCU makes the IPU much more compact and provides a similar amount of trunk space as in a gasoline-powered vehicle.
Ozuchi, Yasuhiro, Tomokage, Ryoji
Process Enables 3D Printing of Nanoscale Metal StructuresTBMG-287004/1/2018
In 3D printing — also known as additive manufacturing — an object is built layer-by-layer, allowing for the creation of structures that would be impossible to manufacture by conventional subtractive methods such as etching or milling.
Q&A: Dr. Manyalibo “Ibo” Matthews, Deputy Group Leader, Laser Materials Group, Lawrence Livermore National Laboratory, Livermore, CATBMG-2827811/1/2017
Dr. Matthews and his team have developed a new laser-based method for 3D printing of large metal objects called Diode-Based Additive Manufacturing (DiAM). It uses high-powered lasers to flash-print an entire layer of metal powder. The process will enable large metal objects to be printed in a fraction of the time typically needed for metal 3D printers.
Functionally Graded Metal-Metal Composite StructuresTBMG-2770010/1/2017
NASA Langley Research Center has developed a functionally graded metal-metal composite structure. The structure is created using a method that avoids deleterious reactions between the different metal constituents, as would be observed via conventional melt processing. The results are unique alloy compositions and arrangements not typically available through conventional processing routes.
The Rapid Rise of Beryllium-Aluminum Alloys in Aerospace17AERP08_016/1/2017
Enhanced performance operating envelopes for aerospace platforms continue to challenge industry limits. Aerospace platform operators demand extreme performance in harsh environments from the aircraft, UAVs, and satellites they deploy today: lighter weight, greater strength, superior fuel efficiency and operational range, vibration-mitigated platforms, low coefficients of thermal expansion, better corrosion resistance - the list goes on. Whether in defense or commercial applications, product competition continues to drive the performance envelope in design, materials selection, and manufacturing of these systems, all the while working to contain costs and meet challenging delivery schedules. In general, materials technologies to increase performance are desired and can be implemented, but they must come with an acquisition or operational cost decrease.
Aluminum Alloy, Sheet 6.5Fe - 1.3Si - 0.60V (8022-H112) Powder Metallurgy Product, Strain HardenedAMS4266B (Current)5/25/2017
This specification covers an aluminum alloy powder metallurgy product in the form of sheet 0.010 to 0.250 inch (0.25 to 6.35 mm) in nominal thickness.
AMS D Nonferrous Alloys Committee
Aluminum Alloy, Sheet 8.6Fe - 1.8Si - 1.3V (8009-H112) Powder Metallurgy Product, Strain HardenedAMS4308B (Current)4/4/2017
This specification covers an aluminum alloy powder metallurgy product in the form of sheet 0.010 to 0.250 inch (0.25 to 6.35 mm) in nominal thickness.
AMS D Nonferrous Alloys Committee
Improvement of the Thermal Durability of an Exhaust Gas Purifying Catalyst Using Size-Controlled Pt-Hydroxide Clusters2016-32-007011/8/2016
An exhaust gas purifying catalyst must be durable, i.e., it must maintain a sufficient catalytic performance even after thermal degradation. Therefore, large amounts of platinum group metals (PGMs), such as Pt, Pd, and Rh, should be loaded onto the catalyst substrate. Exhaust gas heat deteriorates the catalyst by sintering the PGM particles, which decreases the active surface area. It is important to reduce the PGM load and many researchers have therefore attempted to carry out PGM load reduction while maintaining sufficient durability. We found that Pt ions could form Pt-hydroxide clusters in a hexahydroxyplatinate (IV) (Pt(OH)6·H2O) nitric acid solution. The Pt-hydroxide cluster size could be controlled by varying the Pt and nitric acid concentrations and solution temperature. We expected that these “larger Pt-hydroxide clusters” would be efficient at improving the durability because a larger cluster size in the solution would equate to a greater distance between each Pt particle or uniform distribution of Pt particles on the support material. The greater distance or uniform distribution would lower the opportunity for Pt particle association at high temperatures. Therefore, we investigated the catalytic performance of a Pt catalyst containing larger Pt-hydroxide clusters. The Pt catalyst containing larger Pt-hydroxide clusters exhibited an improved catalytic activity after thermal duration. Transmission electron microscopy (TEM) images revealed that the Pt particle distribution was more uniform on the Pt catalyst containing the larger Pt-hydroxide clusters than on the conventional catalyst. This uniformity is assumed to be the reason for the improved durability.
Tsuda, Toyofumi, Miura, Kazuya, Hikasa, Akio, Hosoi, Keiji, Kimata, Fumikazu
High Performance Aluminum Casting Alloys for Engine Applications2016-32-001911/8/2016
In the early 1980's, some promising research and development efforts focused on powder metallurgy revealed that aluminum alloys containing 4 wt% cerium exhibit high temperature mechanical properties exceeding those of the best commercial aluminum casting alloys currently in production. Cerium oxide is an abundant rare earth oxide that is often discarded during the refining of more valuable rare earths such as Nd and Dy. Therefore, the economics are compelling for cerium as an alloy additive. In this paper, we report select results obtained during an investigation of the castability of aluminum-cerium alloys and determine compositional modifications that may be required to ensure the compatibility of the alloy with near net shape casting methods such as advanced sand casting, die casting, permanent mold casting and squeeze casting. Al-Ce alloys were cast in binary composition of 6-16 wt% Ce. Commercially pure aluminum ingots were melted and held at approximately 785°C. Ternary and quaternary alloys with Si and Mg additions were also investigated. Test bars were cast to establish mechanical properties and step plates and hot tear molds were used to determine sensitivity to solidification conditions and hot tearing sensitivity respectively. Finally, air cooled engine cylinder heads were cast in sand molds to get a sense of castability in complicated shape castings.
Weiss, David
Powder Reuse and Its Effects on Laser Based Powder Fusion Additive Manufactured Alloy 7182016-01-20719/20/2016
Laser Based Powder Bed Fusion, a specific application of additive manufacturing, has shown promise to replace traditionally fabricated components, including castings and wrought products (and multiple-piece assemblies thereof). In this process, powder is applied, layer by layer, to a build plate, and each layer is fused by a laser to the layers below. Depending on the component, it appears that only 3-5% of the powder charged into the powder bed fusion machine is fused. Honeywell’s initial part qualification efforts have prohibited the reuse of powder. Any unfused powder that exits the dispenser (i.e., surrounds the build or is captured in the overflow) is considered used. In order for the process to be broadly applicable in an economical manner, a methodology should be developed to render the balance of the powder (up to 97% of the initial charge weight) as re-usable. Though multiple manufacturers may be re-using powder, there is no industry standard methodology or practice for powder re-use. The present study (with 10 uses of the same powder lot) shows no appreciable impact on nickel-base superalloy 718 chemistry, powder size / distribution, or mechanical properties, with exception of gradual increase in oxygen content of the powder.
Hann, Brian A.
Methodology Linking Formulation, Microstructure and Mechanical Properties of Friction Materials2016-01-19109/18/2016
An original methodology is described to characterize mechanical properties of braking sintered material from the microstructure. Firstly, a compressive test on cube extracted from the friction pad is performed. This compressive test is instrumented with a camera leading to use the digital image correlation method giving local information. Indeed, it is possible to identify the elastic and residual strains mechanisms and to make connection with the microstructure. All these information are introduced in a finite element analysis to identify the mechanical properties of the components using an optimization algorithm. As regards of the 2D measurements, it is relevant to confirm the tendency with a 3D information. Secondly, an ex-situ compression test in a micro tomography is performed. This test is coupled to digital image correlation and a 3D simulation is performed exhibiting elastic-plastic behavior and confirming results found in the 2D study. The methodology proposed allows determining nonlinear behavior of friction material but also identifying which components and microstructural mechanisms are involved.
Dufrenoy, Philippe, Magnier, Vincent, MANN, Ruddy, CRISTOL, Anne-Lise, SERRANO, ITZIAR
A Study of Pad Properties vs. Friction, Wear and Brake Squeal: Processing/Porosity Effects2016-01-19159/18/2016
As some brake engineers believe that brake squeal can be related to pad hardness, friction coefficient or compressibility while others disagree, a study has been undertaken to develop further insights. Two commercial formulas, one low-copper NAO and the other copper-free NAO, were made into disc pads of varying porosity without an underlayer and they were checked for specific gravity, porosity, hardness (HRS and HRR), natural frequencies, compressibility, friction, wear and squeal. With increasing porosity, the hardness and natural frequencies continue to decrease. The compressibility definitely does not increase, but rather slightly decrease or stays the same. The coefficient of friction decreases for the low-copper along with pad and disc wear reduction, and increases for the copper-free along with pad wear increase with no change in disc wear. No obvious correlation emerges between brake squeal and pad hardness, friction coefficient or compressibility. After the pads were compressed under 30, 100 and 160 bars, the hardness of the pad surface is found to increase, suggesting permanent compaction under the pressures while the interior of the pad, 5 mm deep, shows slightly increased hardness in the case of 18% and 22% porosity, not in the case of 13% porosity. The results raise a question about the meaning and usefulness of compressibility measurements.
Sriwiboon, Meechai, Rhee, Seong, Kaewlob, Kritsana, Tiempan, Nipon, Samankitesakul, Rungrod
NASA PS400 High-Temperature Solid Lubricant CoatingTBMG-228549/1/2015
NASA has an ongoing need for high-temperature solid lubricant coatings to reduce friction and wear in turbine engines, rocket engines, and other mechanical systems. Such lubricants must be thermally and chemically stable in air, vacuum, and reducing environments like hydrogen. Traditional lubricants like oil, grease, and PTFE (Polytetrafluoroethylene), and even more exotic solid lubricants like graphite and molybdenum disulphide, lack such capabilities. The key problem is to identify and formulate a material that possesses good mechanical properties, long-term environmental durability, and acceptable friction and wear-reducing characteristics while being practical to apply to bearings, seals, and other mechanical components.
Improved Attachment Design for Ceramic Turbine Blades Via Hybrid ConceptsTBMG-225508/1/2015
This innovation is a hybrid metal-ceramic matrix composite (CMC) turbine blade in which a SiC/SiC CMC airfoil section is bonded to a single-crystal superalloy root section in order to mitigate risks associated with an all-CMC blade inserted in a superalloy disk. This will allow current blade attachment technology (SX blade with a dovetail attachment to a slotted Ni disk) to be used with a ceramic airfoil. The bond between the CMC and single crystal will be primarily mechanical in nature, and enhance with clamping arising from thermal expansion mismatch. Two single-crystal root sections will be bonded to each other using diffusion bonding at temperatures near 1,200 °C. The single crystals will form a clamshell around the CMC, with little or no gap between the metal and ceramic. Upon cooling, the metal will shrink around the CMC to firmly clamp it. It is envisioned that this will allow the blade root to operate at temperatures up to about 800 °C. Single crystals will resist stress relaxation at this temperature, thus maintaining clamping loads for long lives. The hybrid concept plus the method of manufacture is new technology.
Development of Pd-Only Catalyst for LEV III and SULEV302015-01-10034/14/2015
This research is aimed at development of the catalyst for gasoline automobiles which uses only palladium (Pd) among platinum group metals (PGMs). And the conformity emission category aimed at LEV III-SULEV30. For evaluation, the improvement effect was verified for 2013 model year (MY) ACCORD (LEV II-SULEV) as the reference. As compared with Pd-rhodium (Rh) catalyst, a Pd-only catalyst had the low purification performance of nitrogen oxides (NOx), and there was a problem in the drop in dispersion of Pd by sintering, and phosphorus (P) poisoning. The following was performed in order to improve these. 1) NOx purification performance was improved using an enhanced basicity support material by promoting the dissociation of N and O in NOx 2) sintering of Pd was controlled using the anchoring effect of praseodymium-zirconia (PrZrOx) 3) poisoning inhibition of Pd and the support material was carried out utilizing the P trapping effect of praseodymium (Pr) Tail pipe emission was set to the LEV III-SULEV30 regulation conformity level by these improvement and optimization.
Kakema, Tomohito, Suehiro, Yukio, Matsuzono, Yoshiaki, Narishige, Takeshi, Hashimoto, Masanori
Elastic Deployable Composite Tubular Roll-Out BoomTBMG-217724/1/2015
The objective of this work was to develop an innovative deployable boom/structure technology that is ultra-lightweight (<30-grams/meter potential), and has extremely compact stowage volume (>100:1 compaction ratio), broad scalability (no size limits envisioned), high deployed frequency, high deployed strength, good thermal/dimensional stability, reliable/immediate and repeatable controlled deployment, high stiffness maintained during the entire deployment sequence, affordability (simple, easily produced tubular structure, very low parts count, and proven tube manufacture provides low cost and rapid assembly), space environmental survivability, and broad mission applicability.
Effect of Phosphorous on Powder Metal Gears2014-01-23359/30/2014
Phosphorous is an important alloying element in powder metallurgy applications. It is used in Powder metal parts for effective Sintering, dimensional stability, improved machinability, corrosion resistance etc. However it does have some negative effects on properties of Powder metal parts. The purpose of the paper is to study the effect of phosphorous on Powder metal gear of Mix A and Mix B having identical composition differing only in phosphorous content. The samples were detailed on each stage, viz. sintering & Heat treatment. In addition two defective samples were studied to observe the extent to which phosphorous may deteriorate the Powder metal Gear.
Natesan, Balakrishnan
A Methodology for Investigating and Modelling Laser Clad Bead Geometry and Process Parameter Relationships2014-01-07374/1/2014
Laser cladding is a method of material deposition through which a powdered or wire feedstock material is melted and consolidated by use of a laser to coat part of a substrate. Determining the parameters to fabricate the desired clad bead geometry for various configurations is problematic as it involves a significant investment of raw materials and time resources, and is challenging to develop a predictive model. The goal of this research is to develop an experimental methodology that minimizes the amount of data to be collected, and to develop a predictive model that is accurate, adaptable, and expandable. To develop the predictive model of the clad bead geometry, an integrated five-step approach is presented. From the experimental data, an artificial neural network model is developed along with multiple regression equations. A multi-layer perceptron network application is employed which uses a feed forward back propagation network architecture for the overall training process through external data consisting of input (process parameters) and target (shape parameters) values. Once a desired level of network training is achieved, simulation results (predicted shape parameters) are generated for a new input data set within the trained network boundary conditions. Furthermore, a comparison between different approaches to sensitivity analysis (clamping technique and sensitivity index) is presented to illustrate the uncertainty in the outputs of the model in relation to its inputs. Experimental validation is conducted by predicting specific process parameters for unique bead geometry. The predicted and resulting bead geometry values are seen within the 95th percentile accuracy.
Aggarwal, Kush, Urbanic, Ruth, Aggarwal, Luv
Aluminum Alloy, Sheet 8.6Fe - 1.8Si - 1.3V (8009-H112) Powder Metallurgy Product, Strain HardenedAMS4308A (Historical)12/4/2013
This specification covers an aluminum alloy powder metallurgy product in the form of sheet 0.010 to 0.250 inch (0.25 to 6.35 mm) in nominal thickness.
AMS D Nonferrous Alloys Committee
Development of Rare Earth-saving Magnet Using Localized Diffusion Method2013-01-17574/8/2013
Nd₂Fe₁₄B sintered magnets are used in the drive motors of hybrid, electric and other vehicles. A magnet in which rare earth content is reduced by means of a localized diffusion method has been developed in order to reduce the volume of dysprosium. The distribution of the demagnetization fields in a motor is not uniform, so the necessary coercivity distribution for the magnets was quantified using Computer-Aided Engineering (CAE). Then material specifications of the localized dysprosium diffusion satisfied with this coercivity distribution was determined, and optimal manufacturing conditions including the position of dysprosium diffusion were set. The coercivity distribution in every position of the magnet using localized diffusion method was inspected. As a result, the magnet was satisfied with coercivity distribution demanded by CAE. Furthermore, evaluation of motor characteristics, especially the demagnetizing characteristic concerned with dysprosium reduction, showed this developed magnet to possess identical characteristics to a conventional magnet. Dysprosium resources represent a particular issue among the rare earths more generally, and the technology developed in this project is able to reduce dysprosium use in magnets by approximately 30% without compromising motor performance.
Higashi, Takayuki, Miyoshi, Takehiro, Kato, Ryutaro, Kono, Michihisa, Inoue, Masashi, Nagumo, Toshiyuki, Fukui, Takahiro, Ohsaki, Kojiro, Iwasaki, Makoto
Less-Invasive Ventricular Assist Device for Late-Stage Heart FailureTBMG-155011/1/2013
The first full-support, miniaturized ventricular assist device designed to be placed in the pericardial space, was approved by the FDA in late November. HeartWare International, Inc., Framingham, MA, an innovator of less invasive, miniaturized circulatory support technologies to treat advanced heart failure, said that its Ventricular Assist System was approved as a bridge to cardiac transplantation in patients who are at risk of death from refractory end-stage left ventricular heart failure.
Modeling of the Elastic Modulus of Brake Pad Materials with High Viscoelastic Content2012-01-17869/17/2012
This work presents the modeling and investigation of the mechanical behavior of brake pad materials with high viscoelastic content, reinforced with particles and fibers. A simplified model is presented, with the purpose of prediction of the elastic modulus of this class of material. The model consists in the modification of the Rule of Mixtures, with the introduction of a term referring to the particle phase present in the composite material. It is introduced an alignment factor, in order to adjust the magnitude of orientation of the fibers in the stage of material compaction process. Also, the influence of the viscoelastic phase is modeled according to the percolation theory. Three standard brake pad materials with different viscoelastic contents were produced and tested. The composite materials produced were tested by three-point bending, in order to determine their mechanical properties. The comparison between mechanical properties obtained experimentally and the theoretical results demonstrate good agreement with the real behavior of the composite material.
Silva, João G. P. da, Pereira, Carlos H. S., Casaril, Alexandre, Varante, Paulo E. D., Al-qureshi, Hazim A.
Self-Sealing Wet Chemistry Cell for Field AnalysisTBMG-146279/1/2012
In most analytical investigations, there is a need to process complex field samples for the unique detection of analytes, especially when detecting low-concentration organic molecules that may identify extraterrestrial life. Wet chemistry based instruments are the techniques of choice for most laboratorybased analysis of organic molecules due to several factors including less fragmentation of fragile biomarkers, and ability to concentrate target species resulting in much lower limits of detection. Development of an automated wet chemistry preparation system that can operate autonomously on Earth and is also designed to operate under Martian ambient conditions will demonstrate the technical feasibility of including wet chemistry on future missions. An Automated Sample Processing System (ASPS) has recently been developed that receives fines, extracts organics through solvent extraction, processes the extract by removing non-organic soluble species, and delivers sample to multiple instruments for analysis (including for non-organic soluble species). The key to this system is a sample cell that can autonomously function under field conditions.
Electronic and Atomistic Roles of Cordierite Substrate in Sintering of Washcoated Catalysts for Automotive Exhaust Gas Emissions Control: Multi-scale Computational Chemistry Approach based on Ultra-Accelerated Quantum Chemical Molecular Dynamics Method2012-01-12924/16/2012
Multi-scale computational chemistry methods based on the ultra-accelerated quantum chemical molecular dynamics (UA-QCMD) are applied to investigate electronic and atomistic roles of cordierite substrate in sintering of washcoated automotive catalysts. It is demonstrated that the UA-QCMD method is effective in performing quantum chemical molecular dynamics calculations of crystals of cordierite, Al₂O₃ and CeZrO₄ (hereafter denoted as CZ). It is around 10,000,000 times faster than a conventional first-principles molecular dynamics method based on density-functional theory (DFT). Also, the accuracy of the UA-QCMD method is demonstrated to be as high as that of DFT. On the basis of these confirmations and comparison, we performed extensive quantum chemical molecular dynamics calculations of surfaces of cordierite, Al₂O₃ and CZ, and interfaces of Al₂O₃ and CZ with cordierite at various temperatures. These calculations coupled with mesoscopic sintering simulations have demonstrated that the cordierite surface forms strong bonds with Al₂O₃ and CZ, which was seen to improve significantly the sintering property of washcoated catalysts under various conditions.
Miyamoto, Akira, Nagumo, Ryo, Suzuki, Ai, Miura, Ryuji, Tsuboi, Hideyuki, Hatakeyama, Nozomu, Takaba, Hiromitsu, Kozawa, Sumio, Chatterjee, Athonu, Okada, Akira
Finite Element Analysis of Friction-Assisted Powder Compaction Process2012-01-00514/16/2012
The major disadvantage of powder metallurgy (PM) is the density gradient throughout the green powder compacts. During the compaction process, due to the existence of friction at powder-tool interfaces, the contact surfaces experience a non-uniform stress distribution having to do with variable friction coefficient and tool kinematics, consequently resulting in density gradient throughout the powder compacts. This represents a serious problem in terms of the reliability and performance of a final product, as the density gradient may contribute to a crack-defect generation during the compaction cycle, and more importantly a non-uniform compact shrinkage during the sintering process. Simulation analyses were conducted using the finite element software, MSC.Marc Mentat, and Shima and Oyane powder constitutive model, to study and suppress the causes of density gradient in the cylindrically shaped green powder compacts. A newly proposed friction-assisted compaction technique was employed, consisting of a moving upper-punch and a die, which uses friction force at the powder-die interface to assist in the compaction of powder. Numerical results are presented and compared with the literature and experimental tests. The simulation analyses had shown that the overall heterogeneity of the corresponding green powder compacts may be considerably reduced by using the proposed friction-assisted compaction technique.
Kostiv, Orest, Behdinan, Kamran, Hashemi, Seyed
Aluminum Alloy, Sheet 6.5Fe - 1.3Si - 0.60V (8022-H112) Powder Metallurgy Product, Strain HardenedAMS4266A (Historical)11/3/2011
This specification covers an aluminum alloy powder metallurgy product in the form of sheet 0.010 to 0.250 inch (0.25 to 6.35 mm) in nominal thickness.
AMS D Nonferrous Alloys Committee
Development of a High Temperature Power Module Technology with SiC Devices for High Density Power Electronics2011-01-262010/18/2011
This paper presents the development of a high density packaging technology for wide band gap power devices, such as silicon carbide (SiC). These devices are interesting candidates for the next aircraft power electronic converters. Effectively they achieve high switching frequencies thanks to the low losses level. High switching frequencies lead to reduce the passive components size and to an overall weight reduction of power converters. Moreover, SiC devices may enable operation at junction temperatures around 250°C. The cooling requirement is much less stringent than for usual Si devices. This might considerably simplify the cooling system, and reduce the overall weight. To achieve the integration requirements for SiC devices, classical wire bonding interconnection is replaced by a stacked packaging using bump interconnection technologies, called sandwich. These technologies offer two thermal paths to drain heat out and present more power integration possibilities. To make reliable sandwich packaging, high temperature solder alloys using low temperature processes are evaluated. Among these assembly techniques, there are the Transient Liquid Phase bonding with Au-Sn solder alloy and the nanopaste silver sintering technique. These techniques are studied as solder assembly solutions to ensure the die-attach and the bumps interconnects. Therefore, the thermo-mechanical behavior of sandwich packaging using silver sintering process and various bump configurations were evaluated under a thermal cycling profile between -40°C and +185°C by means of numerical simulation. Finally, the design optimization of these high temperature packaging technologies is pointed out.
Cissé, Alioune, Massiot, Gregor, Munier, Catherine, Vidal, Paul-Etienne, Carrillo, Francisco, Iturriz, Marcelo
Iridium-Doped Ruthenium Oxide Catalyst for Oxygen EvolutionTBMG-108489/1/2011
NASA requires a durable and efficient catalyst for the electrolysis of water in a polymer-electrolyte-membrane (PEM) cell. Ruthenium oxide in a slightly reduced form is known to be a very efficient catalyst for the anodic oxidation of water to oxygen, but it degrades rapidly, reducing efficiency. To combat this tendency of ruthenium oxide to change oxidation states, it is combined with iridium, which has a tendency to stabilize ruthenium oxide at oxygen evolution potentials. The novel oxygen evolution catalyst was fabricated under flowing argon in order to allow the iridium to preferentially react with oxygen from the ruthenium oxide, and not oxygen from the environment.
Polytetrafluoroethylene (PTFE) Extrusions, Normal Strength, As SinteredAMS3656D (Historical)8/25/2011
This specification covers a virgin, unfilled polytetrafluoroethylene (PTFE) in the form of extruded and sintered rods, tubes, and profiles.
AMS P Polymeric Materials Committee
Molybdenum Disulfide Coating, Thin Lubricating Film, Impingement AppliedAMS2526A (Historical)8/10/2011
This specification covers a coating consisting of finely-powdered molybdenum disulfide in a heat-resistant inorganic binder applied to parts.
AMS B Finishes Processes and Fluids Committee
Polytetrafluoroethylene (PTFE) Extrusions, Premium Strength, As SinteredAMS3657B (Historical)8/9/2011
This specification covers a virgin, unfilled polytetrafluoroethylene (PTFE) in the form of extruded and sintered rods, tubes, and profiles.
AMS P Polymeric Materials Committee
Solvent/Non-Solvent Sintering To Make Microsphere ScaffoldsTBMG-107378/1/2011
A solvent/non-solvent sintering tech- nique has been devised for joining poly- meric microspheres to make porous matri- ces for use as drug-delivery devices or scaf- folds that could be seeded with cells for growing tissues. Unlike traditional sinter- ing at elevated temperature and pressure, this technique is practiced at room tem- perature and pressure and, therefore, does not cause thermal degradation of any drug, protein, or other biochemical with which the microspheres might be loaded to impart properties desired in a specific application. Also, properties of scaffolds made by this technique are more repro- ducible than are properties of comparable scaffolds made by traditional sintering.
Laser Sintering for Customized Medical ApplicationsTBMG-99215/1/2011
Engineers have long been aware of the potential of laser sintering to create innovative and beneficial medical products. Because it is an additive (layer-by-layer) manufacturing process, laser sintering can build parts free of the traditional constraints imposed by machining or molding.
High-Temperature Solid Lubricant CoatingTBMG-83048/1/2010
NASA PS400 is a solid lubricant coating invented for high-temperature tribological applications. This plasma-sprayed coating is a variant of the previously patented PS304 coating, and has been formulated to provide higher density, smoother surface finish, and better dimensional stability.
Zinc-Doped Tricalcium Phosphate Ceramic for Surgical ImplantsTBMG-78705/1/2010
A ceramic body consisting of the phases of tricalcium phosphate and/or hydroxyapatite provides biocompatibility with hard tissues. When such a ceramic body is implanted in a bone, direct connection is formed between the bone and the ceramic body without intervention of any fibrous connective tissues. This zinc-containing or zinc-doped ceramic material mainly consists of tricalcium phosphate and is suitable as a ceramic material for biomedical use. In particular, the material provides surgical implant materials for hard tissue consisting of zinc-doped tricalcium phosphate to promote bone formation by releasing zinc in the body.
Method for Detecting Perlite Compaction in Large Cryogenic TanksTBMG-78164/1/2010
Perlite is the most typical insulating powder used to separate the inner and outer shells of cryogenic tanks. The inner tank holds the low-temperature commodity, while the outer shell is exposed to the ambient temperature. Perlite minimizes radiative energy transfer between the two tanks. Being a powder, perlite will settle over time, leading to the danger of transferring any loads from the inner shell to the outer shell. This can cause deformation of the outer shell, leading to damaged internal fittings.
Silicon Oxycarbide Aerogels for High-Temperature Thermal InsulationTBMG-65701/1/2010
A high-performance, silicon oxycarbide (SiOC) aerogel material is suitable for use as thermal insulation at temperatures approaching 1,200 °C. These aerogel composites were created using cost-effective and commercially available polymeric precursors (the polymethylsiloxane resin, SOC-A35, from Starfire Systems), thus enabling scaleup and mass commercialization. The SiOC aerogels exhibited bulk densities and thermal conductivities that rival traditional silica-based aerogels. Prolonged exposure to temperatures above 1,000 °C had virtually no effect on the thermal conductivity, surface area, pore volume, or pore diameter of SiOC aerogels.
Mechanical Design Limits for a Wrought Cu-15Ni-8Sn Spinodal Alloy2009-01-325511/10/2009
High performance copper alloys are the materials of choice for highly loaded rotating and sliding bearings. The Cu-15Ni-8Sn system is relatively modern, invented in the 1970's, and strengthened by a spinodal transformation that achieves high strength with usable engineering ductility. The development of novel casting technology combined with large scale hot working is largely credited with the ability to produce the large rods, bars, tubes and plate product forms needed by the aerospace industry. Wrought rod, bar and tube properties have been statistically assessed and form the basis for design limits listed in the most current MMPDS (Metallic Materials Properties Development and Standardization) handbook as well as AMS 4596A. The microstructure and metallurgical behavior of Cu-15Ni-8Sn spinodal alloy (C72900 TX00) will be discussed in this paper. Pin bearing, compression and shear strengths as well as physical properties will be described. Fracture characteristics of the microstructure will also be illustrated. SEM and optical metallography show the predominant mechanism for crack movement to be transgranular for highly constrained deformation zones and predominantly intergranular in general. At high magnification the grain boundary fractures show much local ductility.
Cribb, W. Raymond, Grensing, Fritz C.
X-38 Advanced SublimatorTBMG-590911/1/2009
A document discusses a heat rejection device for transferring heat from a space vehicle by venting water into space through the use of a novel, two-stage water distribution system. The system consists of two different, porous media that stop water-borne contaminants from clogging the system and causing operational failures.
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