New Class Of Refractory Ceramics For Thermal Barrier Coatings,
2014
School of Material Science and Engineering, Tsinghua University
New Class Of Refractory Ceramics For Thermal Barrier Coatings, Wei Pan
Thermal Barrier Coatings IV
No abstract provided.
Mixed Convection In Horizontal Channels Heated Below With External Heat Losses On Upper Plate And Partially Filled With Aluminum Foam,
2014
Seconda Università degli Studi di Napoli
Mixed Convection In Horizontal Channels Heated Below With External Heat Losses On Upper Plate And Partially Filled With Aluminum Foam, Bernardo Buonomo, Oronzio Manca, Lorenzo Marinelli, Sergio Nardini
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
In this paper an experimental investigation on mixed convection in air in a heated channel partially filled with an aluminum foam is carried out. The aluminum foam layer is sets on the lower heated wall of the channel. The channel upper plate has a heat transfer toward the external ambient. The investigation allows to evaluate the effect of the aluminum foam on the mixed convection in the heated channel by wall temperature measurements and flow visualization. Results are given for heated channel without and with foam in terms of wall temperature profiles for different Reynolds number value, form 10 to …
Comparative Analysis Of Geometric Models For Predicting The Dynamic Specific Surface Of Foamlike Media,
2014
Stellenbosch University
Comparative Analysis Of Geometric Models For Predicting The Dynamic Specific Surface Of Foamlike Media, Sonia Woudberg, Francois Smit
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
An adaptable geometric pore-scale model is proposed for predicting the specific surface area of actual foams. The proposed model, based on rectangular geometry, is compared to a cubic unit cell model from the literature based on cylindrical struts, a tetrakaidecahedron model as well as a dodecahedron model (both based on either cylindrical of triangular struts). The predicted specific surface areas of the proposed model are of the same order of magnitude as the other model predictions from the literature. The relative percentage errors in the predicted values are at most equal to the relative percentage errors associated with the measured …
Columnar Structured Thermal Barrier Coatings By Thermal Spray Methods,
2014
Forschungszentrum Jülich, Germany
Columnar Structured Thermal Barrier Coatings By Thermal Spray Methods, Robert Vassen, Nadine Schlegel, Stefan Rezanka, Georg Mauer, Emine Bakan, Daniel Mack
Thermal Barrier Coatings IV
No abstract provided.
Multilayered Thermal Barrier Coatings,
2014
Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, China
Multilayered Thermal Barrier Coatings, Xueqiang Cao
Thermal Barrier Coatings IV
A novel non-destructive inspection technique was developed to measure the residual stresses in TBCs by using Eu3+ photoluminescence piezo-spectroscopy. The relationship between the strongest peak of 5D0→7F2 and stress was determined by the high-pressure experiments and used to evaluate the residual stresses. When the top ceramic coat LZ7C3 in the double-layered coating LZ7C3/YSZ:Eu spalled, the inner YSZ:Eu could produce visible luminescence under UV illumination, providing an indication of the spallation location. The LZ7C3/YSZ:Eu coating spalled bit by bit from LZ7C3 to YSZ:Eu during thermal cycling. The similar thermal expansions of LZ7C3 and YSZ:Eu prolonged the thermal cycling life of the …
Synthesis, Characterization And Mechanistic Studies Of Biomolecules@Mesomofs,
2014
University of South Florida
Synthesis, Characterization And Mechanistic Studies Of Biomolecules@Mesomofs, Yao Chen
USF Tampa Graduate Theses and Dissertations
Encapsulation of biomolecules is of great interest to research advances related to biology, physiology, immunology, and biochemistry, as well as industrial and biomedical applications such as drug delivery, biocatalysis, biofuel, food and cosmetics. Encapsulation provides functional characteristics that are not fulfilled by free biomolecules and stabilizes the fragile biomolecules. In terms of biocatalysis, solid support can often enhance the stability of enzymes, as well as facilitate separation and recovery for reuse while maintaining activity and selectivity. Various kinds of materials have been used for encapsulation of biomolecules, among which, porous materials are an important group. Metal-organic frameworks (MOFs) have attracted …
Characterizing The Pore Structure Of Carbonated Natural Wollastonite,
2014
Purdue University
Characterizing The Pore Structure Of Carbonated Natural Wollastonite, Chiara Villani, Robert Spragg, Raikhan Tokpatayeva, Jan Olek, W. Jason Weiss
International Conference on Durability of Concrete Structures
This paper focuses on examining the pore structure of a cementitious paste made with a calcium silicate (wollastonite) that reacts with carbon dioxide and water to form a hardened solid. The pore structure of the hardened solid has been characterized using vapor sorption and desorption, low-temperature differential scanning calorimetry (LT-DSC), and scanning electron microscopy (SEM). The total porosity was also measured using mass measurement in oven-dry and vacuum-saturated conditions. Evidence exists that support the hypothesis that the solid has two main pore sizes: large macropores (>10 nm) appear to form between the initial calcium silicate particles and small micropores …
Thermal Properties Of Highly Porous Fibrous Ceramics,
2014
Aerospace Research Institute of Materials & Processing Technology
Thermal Properties Of Highly Porous Fibrous Ceramics, Jingjing Sun, Zijun Hu, Jiejie Zhuo, Xiaoyan Wang, Chencheng Sun
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
Highly porous fibrous ceramics were fabricated by vacuum-molding the fiber slurry and sintering the dried felt. The materials comprised of a random network of ceramic fibers and air, with the pore sizes on micron scale. The effects of binder content and porosity on the microstructure and room-temperature thermal conductivity of fibrous ceramics were investigated. It was found that the room-temperature thermal conductivity increased with increasing binder content. In addition, the thermal conductivity decreased from 0.18 to 0.06 W/(m·K) when porosity increased from 73% to 90%, showing nearly a linear relationship. The high-temperature thermal conductivity in the range of 200-1200℃ for …
Fabrication And Microstructural Characterization Of Silica Aerogel By Aging Additional Pressurization,
2014
Aerospace Research Institute of Material & Processing Technology
Fabrication And Microstructural Characterization Of Silica Aerogel By Aging Additional Pressurization, Xiaoyan Wang, Zijun Hu, Chencheg Sun, Jiejie Zhou, Zhao Song
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
SiO2 aerogel with Light-weight and low thermal conductivity is a promising candidate for thermal insulator used for aerospace vehicles. In this paper, we report the preparation and microstructural characterization of SiO2 aerogel by aging pressurization using supercritical drying method. The results showed that the aging pressurization can rapid increase the bulk density from 0.1g/cm3 to 0.45g/cm3 with the pressure changing from 200Pa to 600Pa. When the pressure increases to 800Pa, the density was increased to 0.46g/cm3 slowly. Further polycondensation is driven by the increasing of contact area between skeleton particles when the aging pressure increased. The grid structure became densification …
Sensitivity Analysis Of Effective Thermal Conductivity Of Open-Cell Ceramic Foams Using A Simplified Model Based On Detailed Structure,
2014
Technische Universitat Bergakademie Freiberg
Sensitivity Analysis Of Effective Thermal Conductivity Of Open-Cell Ceramic Foams Using A Simplified Model Based On Detailed Structure, Miguel Mendes, Amjad Asad, Pitt Gotze, Eric Werzner, Rhena Wulf, Dimosthenis Trimis, Ulrich Grob, Subhasis Ray
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
The Effective Thermal Conductivity (ETC) of open-cell porous foams can be predicted from the detailed numerical simulation, considering the complex foam structure obtained from three-dimensional (3D) Computed Tomography (CT)-scan images. An alternative approach could be to consider simplified models for a quick and accurate estimation of the ETC. A model for ETC of open-cell porous foams, using such a simplified approach, has been proposed recently which relies upon a single numerical prediction of the dimensionless ETC under vacuum condition, evaluated using the detailed foam structure obtained from 3D CT-scan information. This model is applied in the present study in order …
Droplet Impact And Penetration On Series Of Parallel Tubes,
2014
University of Toronto
Droplet Impact And Penetration On Series Of Parallel Tubes, S. Hosseini, A. Dalili, Nasser Ashgriz, S. Chandra
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
Impact and penetration of a liquid droplet on a substrate having a line of parallel capillary openings drilled along its thickness is experimentally studies. Different regimes of droplet penetration are identified. At low impact velocities, the droplet impacts on the substrate, spreads, and penetrates into the substrate mainly due to the capillary action in each tubular hole. At higher impact velocities, the droplet impacts on the substrate, spreads and penetrates due to the droplet inertia, and then penetrates further due to the capillary action. Threshold velocities for liquid penetration into capillary tubes are identified. Two penetration regimes, capillary and inertia …
The Preparation And Properties Of Novel Structural Carbon Foams Derived From Different Mesophase Pitches,
2014
Aerospace Research Institute of Materials and Processing Technology
The Preparation And Properties Of Novel Structural Carbon Foams Derived From Different Mesophase Pitches, Liqiong Yu, Zhihai Feng, Zhen Fan, Qing Kong, Lin Xu
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
As a novel porous multi-functional carbon material, carbon foams have high bulk thermal conductivity and low density, making them as excellent materials for thermal management systems applications, such as heat exchangers, space radiators, and thermal protection systems. In this paper, the carbon foams with high thermal conductivity, derived from three kinds of mesophase pitches, were fabricated by the process of foaming, carbonization and graphitization. The microstructures of the foams were examined by scanning electron microscopy. It was found that the pores were uniformly distributed, and the pore wall thickened with increasing foams’ density. The properties of the foams were studied, …
Effective Solid-To-Fluid Heat Transfer Coefficient In Egs Reservoirs,
2014
Tsinghua University
Effective Solid-To-Fluid Heat Transfer Coefficient In Egs Reservoirs, Xiao-Long Ouyang, Rui-Na Xu, Pei-Xue Jiang
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
The present work developed a three-equation local thermal non-equilibrium model to predict the effective solid-to-fluid heat transfer coefficient in the enhanced geothermal system reservoirs based on the volume averaging method. Due to the high rock-to-fracture size ratio, the solid thermal resistance effect in the internal rocks cannot be neglected in the effective solid-to-fluid heat transfer coefficient. The present three-equation local thermal non-equilibrium model can consider the dynamic variation of the solid thermal resistance in transient heat transfer by introducing the penetration temperature difference. The model was validated by comparison with pore-scale numerical simulations and macro-scale LTNE model numerical simulations. The …
Improved Permeability Prediction For Heterogeneous Porous Media By Bundle-Of-Leaky-Tubes With Cross-Flow Model,
2014
The University of Oklahoma
Improved Permeability Prediction For Heterogeneous Porous Media By Bundle-Of-Leaky-Tubes With Cross-Flow Model, Faruk Civan
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
An inherently limiting assumption of the Kozeny-Carman equation of permeability is not allowing interaction across the parallel flow through a bundle of tubes model. While this condition can be observed for flow through sufficiently high porosity homogeneous porous media, the Kozeny-Carman equation cannot represent the permeability of low porosity heterogeneous porous media. This paper presents a modeling of flow through a leaky-flow tube allowing interactions with flow occurring in other flow tubes in a bundle of tubes model of porous media. Then, the effect of such interactions is taken into account by incorporating the pore connectivity by means of the …
Porous Structures Used As Flameproof Pressure Relief Elements A Novel Approach Of Flameless Venting,
2014
Physikalisch Technische Bundesanstalt
Porous Structures Used As Flameproof Pressure Relief Elements A Novel Approach Of Flameless Venting, Julia Hornig, Detlev Markus, Martin Thedens
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
Here, a novel approach to flameless venting is presented, which offers the possibility of improving the design of flameproof enclosures without reducing any safety aspects. This approach is based on the integration of porous structures – such as traditional sintered metals or sintered metal fibers – into the enclosure walls acting as venting and flame-quenching elements. It is shown that proper use of these structures can enormously decrease the maximum explosion pressure while safely avoiding flame transmissions, even for a large number of consecutive internal explosions. However, the transmission of a gas explosion through porous structures is a transient and …
Keynote – Nonlinear Natural Convection In Porous Media And The Collapse Of The Wave Function,
2014
Northern Arizona University
Keynote – Nonlinear Natural Convection In Porous Media And The Collapse Of The Wave Function, Peter Vadasz
5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry
A short review of the problem of nonlinear natural convection in a fluid saturated porous layer heated from below is presented. When the conditions for the onset of convection are met a wave function is obtained as the solution of the linearized equations expressed in terms of a Fourier expansion. Only one mode of this expansion survives at the onset of convection, a result that can be seen as the "Collapse of the Wave function" in a very similar fashion as in quantum mechanics, although the explanations of the latter are very distinct from the ones in quantum mechanics. The …
Effect Of Bondcoat Roughness On Lifetime Of Aps-Tbc Systems In Dry And Wet Gases,
2014
Research Center Julich
Effect Of Bondcoat Roughness On Lifetime Of Aps-Tbc Systems In Dry And Wet Gases, W.J. Quadakkers, D. Naumeko, P. Mor, W. Nowak, L. Singheiser
Thermal Barrier Coatings IV
Low pressure plasma spraying (LPPS) is a process commonly used for deposition of MCrAlY (M=Ni,Co) bondcoats for air plasma spray thermal barrier coatings (APS-TBCs). LPPS produces bondcoats with a high roughness and good oxidation resistance, which are known to play a key role for long lifetimes of APS-TBC’s. An alternative process for the bondcoat deposition is high velocity oxy-fuel (HVOF), which is substantially cheaper than LPPS but even with well optimized spraying parameters generates intrinsically lower bondcoat roughness. In the present work it is shown that a bi-layer MCrAlY-bondcoat consisting of an HVOF-base layer and an upper, thin APS-flashcoat of …
Application Of Eq Bond Coat To Eb-Pvd Tbc Systems,
2014
National Institute for Materials Science
Application Of Eq Bond Coat To Eb-Pvd Tbc Systems, Kazuhide Matsumoto, Kyoko Kawagishi, Yutaka Koizumi, Hiroshi Harada
Thermal Barrier Coatings IV
To prevent the formation of SRZ in the log-time high-temperature exposure of the turbine blades, thermodynamically equilibrium phase such as gamma-prime phase of the substrate is use as an oxidation-resistant bond coat. The previous study clarified that this EQ coating shows excellent interface stability and it does not degrade mechanical strength due to the SRZ formation. In this study, TBC life test of EB-PVD ceramics coated EQ coating is investigated with other conventional MCrAlY coatings. The 4th and 5th generation superalloys are used for substrates. About 150 μm thick of EQ coating, conventional NiCoCrAlY and CoNiCrAlY coating are deposited by …
The Role Of Reactive Elements In Improving The Cyclic Oxidation Performance Of Β- Nial Coatings,
2014
School of Material Science and Engineering, China
The Role Of Reactive Elements In Improving The Cyclic Oxidation Performance Of Β- Nial Coatings, Hongbo Guo, Hui Peng, Dongqing Li, Tian Zhang, Shengkai Gong
Thermal Barrier Coatings IV
the bond coat in thermal barrier coating (TBC) system. However, the oxide scale grown on NiAl spalls readily during high-temperature cyclic oxidation. Reactive elements (REs) as well as their oxides dispersions were investigated to improve the cyclic oxidation performance. In this work, the effects of several REs on the adherence of Al2O3/NiAl interface were investigated by first principles theory calculations and experiments. We find that the solubility of the REs in NiAl alloy arrive at an order of Hf >Zr>Dy>Y>La, all the REs exhibit an affinity for sulfur, with an order of La>Dy>Y>Zr>Hf, …
A Recent History Of Thermal Barrier Coatings For Aero-Propulsion Applications,
2014
Pratt & Whitney
A Recent History Of Thermal Barrier Coatings For Aero-Propulsion Applications, Brian Hazel, Michael J. Maloney
Thermal Barrier Coatings IV
Thermal barrier coatings for aero-propulsion operation have been in use since the 1960s. These thermal barrier coatings are composed of an oxidation resistant metallic base layer and a thermally resistant ceramic top layer. The development and implementation of advances in both the metallic base and the ceramic top layer will be explored. The evolution has included performance and durability improvements, process advances, and understanding and evolution of failure modes. More recent efforts have focus on future challenges for thermal barrier coatings to meet ever increasing operating temperature demands of future applications.
