Engineering Commons^™

Γ/Γ' Co-Base Superalloys – New High Temperature Materials Beyond Ni-Base Superalloys?, Steffen Neumeier, Christopher H. Zenk, Lisa P. Freund, Mathias Göken

Beyond Nickel-Based Superalloys II

In 2006 a new L1₂ phase, Co₃(Al,W), was discovered in the Co-Al-W system which has led to the development of novel Co-base superalloys with g/g¢ microstructures similar to those of the well-established Ni-base superalloys. First investigations on simple ternary alloys could show that these Co-Al-W based alloys exhibit higher solidus temperatures and show less segregations after casting compared to typical Ni-base superalloys. This leads to the question whether this g/g¢ Co-base superalloys can be regarded as new class of high temperature materials that can compete with or even supersede established Ni-base superalloys.

In the first part of …

Microstructural Analysis And High Temperature Creep Of Mo-9si-8b Alloys With Al And Ge Additions, Peter Kellner, Rainer Völkl, Uwe Glatzel

Beyond Nickel-Based Superalloys II

Refractory metals and their alloys show potential for high temperature applications, due to the increased melting point and creep resistance. Spark plasma sintering technology as well as argon arc melting is used to prepare quaternary and quinternary Mo-9Si-8B-xAl-yGe (x is 0 or 2; y is 0 or 2) samples. Compositions are stated in at.%. All the compositions consist of a Mo solid solution (α-Mo) and two intermetallic phases: Mo₃Si (A15) and Mo₅SiB₂ (T₂). On the one hand, no zirconium is added to the alloys to avoid evaporation of MoO₃ due to the …

Enhanced Oxidation Resistance Of Ti-Rich Mo-Si-B Alloys By Pack-Cementation Process, Camelia Gombola, Daniel Schliephake, Martin Heilmaier, John H. Perepezko

Beyond Nickel-Based Superalloys II

To increase efficiency by higher combustion temperatures of aircraft engines and energy generation, new high temperature materials are inevitable. Mo-Si-B alloys for example satisfy several requirements such as good oxidation and creep resistance. Recently, novel Ti-rich Mo-Si-B alloys have shown an increased creep resistance compared to Ti-free Mo-Si-B alloys by the formation of Ti-silicide precipitates during processing. However, due to the formation of a duplex SiO₂ – TiO₂ oxide layer, where fast inwards diffusion of oxygen takes place, the oxidation resistance is poor.

In this study we show that oxidation resistance of Mo-Si-B-Ti alloys can be enhanced drastically …

Microstructural Stability Of Co-Re-Cr-Ta-C Alloy Strengthened By Tac Precipitates, Debashis Mukherji, Ralph Gilles, Lukas Karge, Pavel Strunz, Přemysl Beran, Joachim Rösler

Beyond Nickel-Based Superalloys II

It is becoming increasingly clear that new materials that can operate at substantially higher temperatures than Ni-base superalloys are needed for future gas turbines. High melting Co-Re-Cr based alloy strengthened by carbides, particularly the MC type carbide, shows promise [1]. A fine dispersion of globular TaC precipitate is exploited for this purpose. Additionally Cr, which is mainly added to improve oxidation resistance, also stabilizes lamellar M₂₃C₆ type Cr carbide. The microstructure of a Co-Re-Cr-Ta-C alloy with the two types of carbides is seen in Fig. 1.

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Mo-9si-8b Alloys With Additons Of Zr – Microstructure And Creep Properties, Uwe Glatzel, Christian Hochmuth, Rainer Völkl

Beyond Nickel-Based Superalloys II

Three phase Mo-9Si-8B (at.%) alloys are a prominent example for a potential new high temperature structural material. Due to their high melting point and excellent creep resistance. In this study the effect of Zr addition (0…4 at.%) on the microstructure and creep properties of Mo-9Si-8B (at.%) alloys is investigated. Two powder metallurgical processes, hot isostatic pressing (HIP) and spark plasma sintering (SPS), are used to prepare specimens. The resulting microstructures are examined using SEM and TEM analysis. SPS alloys exhibit smaller grain sizes and fewer oxides compared to the HIP alloys, because of the oxygen availability during HIP. The more …

Microstructure And Creep Resistance Of Ti-Rich Mo + Mo5si3 + Mo5sib2 Alloys, Daniel Schliephake, Martin Heilmaier

Beyond Nickel-Based Superalloys II

New materials are necessary to increase efficiency of power generation and aircraft engines by higher combustion temperatures. Recently, it was found that alloying with high amounts of Ti replaces Mo₃Si by Mo₅Si₃ and stabilizes the phase field Mo + Mo₅Si₃ + Mo₅SiB₂, which could be beneficial for higher oxidation resistance, since Mo₅Si₃ is more oxidation resistant than Mo₃Si. Additional, Ti-rich Mo-Si-B alloys show an increased creep resistance compared to Ti-free Mo-Si-B alloys and a significant reduction in the alloy density. However, using the …

Design Of Gamma-Prime-Strengthened Co-Based Superalloys: Where We Are And Where We Need To Go, Eric A. Lass

Beyond Nickel-Based Superalloys II

Since the first report of a stable two-phase g-g’ (FCC-L12) phase field in ternary Co-Al-W in 2006, there has been significant research effort in developing this new class of Co-based g’-strengthened superalloys for high temperature applications. Much of the focus has been on characterizing and improving high temperature properties such as the g’ solvus temperature, high temperature strength and creep resistance, corrosion and oxidation behavior. Much of this work has been conducted experimentally utilizing the wealth of knowledge of Ni-based superalloys gathered over the last several decades. Efforts into developing effective modeling tools, such as thermodynamic and diffusion databases, have …

Improving The Oxidation Resistance Of Refractory Metals Via Aluminum Diffusion Coatings And Halogen Effect, A.S. Ulrich, M.C. Galetz

Beyond Nickel-Based Superalloys II

Recently, refractory metals and their alloys have received increasing attention for the purpose of substituting Ni-based single crystal superalloys. Compared to commonly used materials, refractory metals have significantly higher melting points while their mechanical properties seem adequate at high temperatures. The main challenge for their application is, that refractory metals show low oxidation resistances at elevated temperatures. Aluminum diffusion layers are promising coatings to suppress harmful oxidation by forming a protective oxide layer. This study deals with the application of such aluminum reservoir layers and with the investigation of their protective properties. Four different unalloyed refractory metals, molybdenum, tantalum, tungsten …

Conference Program, Howard J. Stone

Beyond Nickel-Based Superalloys II

No abstract provided.

From Dilute Polyelectrolyte Solutions To Entangled Polyelectrolyte Networks: A Study Of Sodium Carboxymethyl Cellulose In Water By Light Scattering And Rheology, Juliette S. Behra, Timothy N. Hunter, Olivier J. Cayre, Johan Mattsson

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Sodium carboxymethyl cellulose (Na CMC) is widely used in industry for its thickening and swelling properties. Applications are very broad and include pharmaceutical, food, home and personal care products as well as the paper industry, water treatment and mineral processing. Na CMC is a linear negatively charged water-soluble polymer derived from cellulose. Its behaviour in water is known to be very complex and a function of several parameters including the characteristics of the polymer itself [1] such as molecular weight and degree of substitution as well as the solution concentration and dissolution conditions [2] (e.g. addition order of the system …

Soft Matter Films Interfaced To Electronic Devices: Capacitance-Modulated Field Effect Transistors Integrating Protein Layers, Gerardo Palazzo, Luisa Torsi, Maria Magliulo, Antonia Mallardi

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Soft matter systems interfaced to an electronic device are presently one of the most challenging research activity that has relevance not only for fundamental studies but also for the development of highly performing bio-sensors.

Layers of proteins anchored on solid surfaces have small capacitance that undergoes to only minute changes as the ligand–protein complex is formed.

For properly designed systems, the protein layer represents smallest capacitance in a series of capacitors and as such dominates the overall capacitance. When such a protein layer is integrated in a Field Effect Transistor (FET) transduction is remarkably sensitive as the transistor output current …

Relative Humidity As A New Parameter In Rheological Testing, Jörg Läuger, Gunther Arnold

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Besides temperature and pressure the water content of a sample as well as the relative humidity of the ambient air are important parameter influencing the rheological behavior of many complex fluids such as for example gels, biomaterials, polymeric systems, food products, and adhesives.

The aim of this contribution is to introduce a newly designed environmental control chamber for the use with a rotational rheometer.

A combination of a modified convection oven and an external humidity generator enables to work under defined relative humidity (RH) and temperature (T) in the ranges of RH = 5 to 95 % and T = …

Passive Microrheology As A Useful Tool For Milk Gel Analyses, Roland Ramsch, Giovanni Brambilla, Mathias Fleury, Pascal Bru, Gérard Meunier

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Passive microrheology based on Diffusing Wave Spectroscopy (DWS) [1,2] is presented as a straightforward tool for the analysis of milk gel preparation. Diffusing Wave Spectroscopy consists of analysing the interferential images of light, which is backscattered by the sample. This so called speckles images, which are detected by a CCD camera, change in time due to the Brownian motion of the particles that scatter the light. The variation of the images as a function of time can be directly correlated to the viscoelastic properties of the sample. As it is an optical method, it is perfectly adapted to study the …

Non-Uniform Flow Of Colloidal Glasses And Gels: The “Shear-Gradient Concentration Coupling Instability”, J.K.G. Dhont

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

There are several types of shear-induced instabilities in soft-matter systems, like vorticity- and gradient-banding, that are by now well-understood. There is, however, an instability that can be referred to as “the Shear-gradient Concentration Coupling instability” (the SCC-instability) that has been largely ignored due to the lack of understanding of its microscopic origin, since its phenomenological description a few decades ago. This instability is due to a postulated shear-gradient induced mass flux together with a strong coupling of the stress to concentration. The origin of the shear-induced mass flux resulting from direct interactions is so far not understood, and explicit expressions …

Conference Program, Samiul Amin, Saad Khan

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

No abstract provided.

Super-Soft And Super-Elastic Dry Gels, Michael Rubinstein, William F. M. Daniel, Mohammad V. Vatankhah, Joanna Burdyńska, Krzysztof Matyjaszewski, Jaroslaw Paturej, Sergey Panyukov, Andrey V. Dobrynin, Li-Heng Cai, Thomas E. Kodger, Rodrigo E. Guerra, Adrian F. Pegoraro, David A. Weitz, Sergei S. Sheiko

Colloidal, Macromolecular & Biological Gels: Formulation, Properties & Applications

Molecular combs and bottlebrushes are a new class of polymer architecture allowing for anomalously low density of entanglements in polymer melts. The conformations and rheological properties of melts of these branched macromolecule composed of a flexible backbone and side chains densely tethered to it are investigated theoretically, experimentally and by computer simulations.^1,2 We develop the rule for dialing in the desired value of the melt plateau modulus of these molecules as low as 1000 times below the conventional values for linear polymer melts and experimentally verify the validity of our theory. The theory also predicts that elastomers made from …

Direct Numerical Simulation Of Reactive Flow Through A Fixed Bed Of Catalyst Particles, Abdelkader Hammouti, Florian Euzenat, Daniel Rakotonirina, Anthony Wachs

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Many catalytic refining and petrochemical processes involve two-phase reactive systems in which the continuous phase is a fluid and the porous phase consists of rigid particles randomly stacked. Improving both the design and the operating conditions of these processes represents a major scientific and industrial challenge in a context of sustainable development. Thus, it is above all important to better understand all the intricate couplings at stake in these flows: hydrodynamic, chemical and thermal contributions. The objective of our work is to build up a multi-scale modelling approach of reactive particulate flows and at first to focus on the development …

An Innovative Culture Technique For Microalgae Using Hollow Fiber Membranes, Yoshihiko Sano, Takeshi Suzuki, Akira Nakayama

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

A hollow fiber culture system has been proposed for supplying the carbon dioxide to the microalgae, to replace the conventional air bubbling system which has been adopted to supply carbon dioxide in most conventional microalgal culture. In order to examine the usefulness of hollow fiber membranes for the microalgal culture, the microalgal growth rate for Chlorella sp. and the effective mass transfer coefficient of carbon dioxide through the hollow fiber membranes have been measured using the proposed photobioreactor filled with hollow fibers. The microalgal growth rate using hollow fiber membranes was found to be three times greater than that observed …

Active Nanomaterials For Biomedical Applications, Gianni Ciofani

Nanotechnology in Medicine: From Molecules to Humans

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Numerical Investigation Of The Phase Change In Transpiration Cooling With The Vof Method, Xiao-Long Ouyang, Pei-Xue Jiang

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Transpiration cooling with phase change is numerically investigated in the present work. As shown in Figure 1, a liquid coolant flow is injected into a porous medium from the bottom side. The porous medium receives heat from the hot gas on the top surface and heats the coolant. Thus, phase change can occur in this porous medium. The surface temperature, the heat flux received by the porous medium, the phase distribution and the flow and cooling characteristics are the most important unknowns on this topic.

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Modeling Flow, Heat And Mass Transfer In A Porous Biomass Plug - When Used In An Electrically Heated Tobacco System, Markus Nordlund, Arkadiusz K. Kuczaj

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Heating porous biomass samples is utilized in many industries for drying or extracting Volatile Organic Compounds (VOC) from the biomass. The heating may trigger physical and chemical processes within the material, such as release of VOC, thermal degradation and evaporation. Most of the processes triggered by the increased temperature are occurring simultaneously and are strongly interdependent. For most practical applications, it is important to have control of the complex processes occurring during heating to generate stable and controllable release of VOC. This is the case for products delivering the released VOC to consumers by inhalation, as is the case of …

A Mini-Review On The Fractal-Monte Carlo Method And Its Applications In Porous Media, Boming Yu

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Porous media widely exist in nature such as soil, rocks, sandstones, oil/gas//water reservoirs, biological tissue and organics, etc., and in many sciences and engineering applications. Since microstructures of porous media are extremely complicated, this makes very difficult to predict the transport properties such as thermal conductivities and permeabilities of porous media by analytical solutions. Usually, numerical simulations such as control volume method, molecular dynamics and Lattice Boltzmann method etc. are often applied. However, results by numerical simulations are often correlated as empiric expressions, which usually contain one or more empiric constants.

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Generation Of Simple Extended Porous Surface Expression From Results Of Pore-Level Conjugate Heat Transfer In Spherical-Void-Phase Porous Blocks, Anthony G. Straatman, Alex Kalopsis, Nolan Dyck

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Studies of convection in porous media continue to be of scientific interest due to the increasing utility of highly-conductive porous materials in heat exchange applications. Of central interest is the ability to model flow and heat transfer through a porous material with high accuracy in a manner that is computationally inexpensive. To this end, use of thermal-equilibrium (TE) or non-thermal-equilibrium (NTE) volume–averaged techniques are of great interest, but use of such methods requires information that is averaged out to be supplied as model coefficients for simple constitutive models that characterize the physical processes. Such models and coefficients are typically derived …

Combined Effects Of Internal Heat Generation And Viscous Dissipation For Double Diffusive With Forchheimer Fluid Model, Dinesh P.A., Rushi Kumar B., Suresh Babu R

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

In this paper, a numerical study using shooting technique is applied for a double diffusive flow for the combined effects of internal heat generation and viscous dissipation over a vertical heated plate under the influence of variable fluid properties is carried out. The governing equations of the physical problem are non-linear and coupled partial differential equations for velocity, temperature and concentration distributions. Using a suitable similarity transformation, the governing equations are transformed to ordinary differential equations involving the various non-dimensional parameters of the problem.

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Effects On The Pore Structure And Permeability Change By Coke Deposition During Crude Oil In-Situ Combustion, Qianghui Xu, Bin Ma, Hang Jiang, Ran Xu, Chao Huang, Lin Shi

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

In-situ combustion(ISC) is an enhanced oil recovery technique to exploit the unconventional crude oil resources with high recovery efficiency. Great amount of reaction heat is released in-place by burning the solid residue, so-called coke at the combustion front with the temperature higher than 400℃. Significant open ISC questions include the effect of coke formation on the pore structure and permeability. Coke deposition reduces the permeability and increases the permeability heterogeneities which will affect the oxygen transport in the formation, thereby influencing the oxygen participating reactions downstream. However, the existing empirical or semi-empirical relationships are still questionable to model the permeability …

Experiments Of Water's Effect On Mechanical Properties Of Shale Rocks, Fuquan Song, Fuying Qi

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

The multiple hydraulic fracturing is an indispensable means to improve the production mass of natural gas in development of shale gas. The fracturing water consumption of a horizontal well reaches 10x103 m3. However, the water been injected into shale layer is not reverse discharged completely. How does this part of water stays in shale layer? What's the role it plays? And how does it have any effects on the development? We studied effects of water on shale rock mechanical properties experimentally to answer these questions.

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Numerical Simulation Of Thermal Energy Storage With Phase Change Material And Aluminum Foam, Bernardo Buonomo, Oronzio Manca, Davide Ercole, Sergio Nardini

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

A Latent Heat thermal energy storage system (LHTESS) is employed as a thermal buffer, since it avoids the intermittent supply of thermal energy due to the behaviour of the thermal source, in particular the renewable thermal source like the solar radiation. Therefore a LHTESS allows supplying the thermal energy in continuous way. The principal material of a LHTESS is the phase change material (PCM) given that it storages a high quantity of thermal energy during its phase change process thanks to the high value of latent heat. Moreover the thermal energy is stored at quasi-constant temperature because during the phase …

Effect Of The Variable Porosity On The Heat Transfer Process In Solar Air Receiver, Pei Wang, D. Y. Liu

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Solar air receiver is the core component of central receiver system (CRS) in solar thermal power plants due to the unique feature of some porous medium like silicon carbide foam ceramic and so on. In the air receiver, the porous material receives the concentrated sunlight from the heliostat field and heats up the pumped inlet air by convection and radiation. The incident radiation is distributed in the inner space of the porous medium rather than located on the boundary of the heated face in the front of the receiver. Aiming at this phenomenon which called volumetric effect, we propose a …

Internal Heat Generation Effect On Mixed Convection Heat And Mass Transfer Over A Vertical Heated Plate With Soret And Dufour Effects, Dinesh P.A., Nalinakshi N., Chandrashekhar D. V.

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

Study and analysis of internal heat generation effect of two-dimensional, steady, laminar, heat and mass transfer mixed convection flow of a viscous incompressible fluid from a vertical heated plate embedded in a sparsely packed porous medium with variable fluid properties such as permeability, porosity, thermal conductivity and solutal diffusivity with the Soret and Dufour effects are considered and studied numerically. The boundary layer flow in the porous medium is governed by Lapwood-Forcheimer-Brinkman extended Darcy model.

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Proposal Of Utilizing Uni-Directional Porous Copper For Extremely High Heat Flux Removal, Kazuhisa Yuki, Kio Takai, Yoshiki Indou, Koichi Suzuki

Sixth International Conference on Porous Media and Its Applications in Science, Engineering and Industry

This paper proposes new heat removal devices utilizing uni-directional porous copper against extremely high heat flux conditions. Before designing those, we discuss some key parameters of porous media to enable a high heat flux removal over 10 MW/m² at a low flow rate of water, which are effective thermal conductivity, permeability, liquid supply to a heat transfer surface, and contact thermal resistance between the porous medium and the heat transfer surface. These discussions indicate utilizing the uni-directional porous media as shown in Fig. 1 from the view point of its higher thermal conductivity, direct supply of cooling liquid toward …