Hexaaluminate Catalysts for Fuel Reforming

2008 ◽  
Author(s):  
Nicholas E. McGuire ◽  
Neal P. Sullivan ◽  
Robert J. Kee ◽  
Huayang Zhu ◽  
James A. Nabity ◽  
...  
Keyword(s):  
Flow Reactor ◽  
Exchange Process ◽  
Catalyst Support ◽  
Temperature Stability ◽  
Metal Exchange ◽  
High Temperature Stability ◽  
Fuel Reforming ◽  
Transmission Electron ◽  
Wide Range ◽  
Hexaaluminate Catalysts

Hexaaluminate catalysts offer excellent high-temperature stability compared to the equivalent metal-based catalysts. Their stability also lends well to use as a catalyst support. However, use of novel hexaaluminates is limited in fuel processing for fuel-cell applications. In this paper, we report on the performance of hexaaluminates as a catalyst support in the steam reforming of methane. The hexaaluminates are synthesized by a metal-exchange process using alumoxane precursors that enable a wide range of metal substitutions. Performance is evaluated using a unique stagnation-flow reactor that enables detailed probing of the boundary layer above the catalyst-impregnated stagnation surface. Experimental results are compared with models to understand fundamental reaction kinetics and optimize catalyst performance. RhSr-substituted hexaaluminates with a Rh impregnation are shown to yield the best performance. Scanning- and Transmission-Electron Microscopy are used to characterize the different types of hexaaluminates, and to examine the effect of aging on catalyst structure.

Tailored Solutions for Off-Shore Applications by Plazjet Sprayed Coatings

1997 ◽  
Author(s):  
F. Ladru ◽  
E. Lugscheider ◽  
H. Jungklaus ◽  
C. Herbst ◽  
I. Kvernes
Keyword(s):  
Process Control ◽  
Thermal Spraying ◽  
Temperature Stability ◽  
Hard Coatings ◽  
High Temperature Stability ◽  
Coating Quality ◽  
Large Structures ◽  
Wide Range ◽  
Sprayed Coatings ◽  
Suitable Process

Abstract For very large structures and parts in critical environments, a materials solution often cannot be found by using one material. The specific desired properties for those structures, like stiffness, ductility, high temperature stability, corrosion resistance, etc. are difficult to fulfill with only one material. In this case a solution may be found by using coatings and design their specific properties to replenish each other by their combination. The Thermal Spraying processes offer the necessary flexibility of producing thin to thick, ductile, soft to hard coatings while due to the wide range of process temperatures it is possible to process a wide range of materials, both as coating and structure. In this paper the some recent and important developments in Thermal Spraying to produce coatings for technical demanding structures will be described. These developments consist of High Power Plasma Spraying, powder- and process control development. To ensure process consistency during long spraying times and to apply reproducible coating quality a suitable process control is of great importance and the development of temperature control by Pyrometry and Thermography will be presented. The example will be drawn according to the application of a coating on a ball valve for off-shore and ship diesel engine parts (piston and valve).

High-Temperature Spin-On Adhesives for Temporary Wafer Bonding

2007 ◽  
Vol 4 (3) ◽  
pp. 105-111 ◽  
Author(s):  
S. Pillalamarri ◽  
R. Puligadda ◽  
C. Brubaker ◽  
M. Wimplinger ◽  
S. Pargfrieder
Keyword(s):  
High Temperature ◽  
Wafer Bonding ◽  
Heat Dissipation ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Performance Requirements ◽  
Wide Range ◽  
Bonding Properties ◽  
Partial List ◽  
Wafer Thinning

Wafer thinning has been effectively used to improve heat dissipation in power devices and to fabricate flexible substrates, small chip packages, and multiple chips in a package. Wafer handling has become an important issue due to the tendency of thinned wafers to warp and fold. Thinned wafers need to be supported during the backgrinding process, lithography, deposition, etc. Temporary wafer bonding using removable adhesives provides a feasible route to wafer thinning. Existing adhesives meet only a partial list of performance requirements. They do not meet the requirements of high-temperature stability combined with ease of removal. This paper reports on the development of a wide range of temporary adhesives to be used in wafer thinning applications that use both novel and conventional bonding and debonding methods. We have developed a series of novel removable high-temperature spin-on adhesives with excellent bonding properties and a wide range of operating temperatures for bonding and/or debonding to achieve a better processing window.

scholarly journals Probing the Nanoscale Heterogeneous Mixing in a High-Performance Polymer Blend

Polymers ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 192
Author(s):  
Alexander Paul Fellows ◽  
Debashis Puhan ◽  
Janet S. S. Wong ◽  
Michael T. L. Casford ◽  
Paul B. Davies
Keyword(s):  
High Performance ◽  
Domain Boundary ◽  
Temperature Stability ◽  
Chemical Information ◽  
High Temperature Stability ◽  
Force Microscopy ◽  
Domain Structures ◽  
Wide Range ◽  
Physical Mixing ◽  
Cantilever Probes

The blend of polyetheretherketone (PEEK) and polybenzimidazole (PBI) produces a high-performance blend (PPB) that is a potential replacement material in several industries due to its high temperature stability and desirable tribological properties. Understanding the nanoscale structure and interface of the two domains of the blend is critical for elucidating the origin of these desirable properties. Whilst achieving the physical characterisation of the domain structures is relatively uncomplicated, the elucidation of structures at the interface presents a significant experimental challenge. In this work, we combine atomic force microscopy (AFM) with an IR laser (AFM-IR) and thermal cantilever probes (nanoTA) to gain insights into the chemical heterogeneity and extent of mixing within the blend structure for the first time. The AFM-IR and nanoTA measurements show that domains in the blend are compositionally different from those of the pure PEEK and PBI polymers, with significant variations observed in a transition region several microns wide in proximity to domain boundary. This strongly points to physical mixing of the two components on a molecular scale at the interface. The versatility intrinsic to the combined methodology employed in this work provides nano- and microscale chemical information that can be used to understand the link between properties of different length scales across a wide range of materials.

scholarly journals A Low-Temperature Alumina/Copper Diffusion Bonding Process using La-Doped Titanium Interlayers

Coatings ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 401 ◽  
Author(s):  
Cherng-Yuh Su ◽  
Jia-Liang Huang ◽  
Po-Chun Chen ◽  
Hsin-Jung Yu ◽  
Dai-Liang Ma ◽  
...  
Keyword(s):  
Low Temperature ◽  
Diffusion Bonding ◽  
Bonding Temperature ◽  
Oxygen Affinity ◽  
Temperature Stability ◽  
High Strength ◽  
High Temperature Stability ◽  
Transmission Electron ◽  
Temperature Diffusion ◽  
La Doped

Ceramic-to-metal heterojunctions have been established to improve high-temperature stability for applications in aerospace and harsh environments. In this work, we employed low-temperature diffusion bonding to realize an alumina/Cu heterogeneous joint. Using a thin layer of lanthanum-doped titanium (La-doped Ti) to metallize the alumina surface, we achieved the bonding at a temperature range of 250–350 °C. We produced a uniform, thermally stable, and high-strength alumina/Cu joint after a hot-press process in vacuum. Signals from X-ray diffraction (XRD) suggested the successful diffusion of Ti and La into the alumina substrate, as Ti can easily substitute Al in alumina, and La has a better oxygen affinity than that of Al. The transmission electron microscopy and XRD results also showed the existence of CuxTiyO phases without CuxTiy or LaOx. In addition, the bonding strength of alumina/copper hot-pressed at 250, 300, and 350 °C were 7.5, 9.8 and 15.0 MPa, respectively. The process developed in this study successfully lowered the bonding temperature for the alumina/copper joint.

Influence of Deformation on Aging Precipitation Behavior of an Al-Cu-Mg-Si Alloy

2014 ◽  
Vol 936 ◽  
pp. 1247-1251 ◽  
Author(s):  
Xi Wu Li ◽  
Bai Qing Xiong ◽  
Yong An Zhang ◽  
Yan Qi Zeng ◽  
Feng Wang ◽  
...  
Keyword(s):  
Cold Deformation ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Precipitation Behavior ◽  
Scanning Calorimetry ◽  
Σ Phase ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Aging Precipitation ◽  
Stretching Deformation

To meet the stringent requirements of heat-resistance products for aerospace applications, an Al-4.0Cu-1.3Mg-0.6Si alloy containing a cubic σ phase (Al5Cu6Mg2) with excellent high temperature stability was developed. Influence of deformation on aging precipitation behavior of the alloy was investigated by transmission electron microscope (TEM) and differential scanning calorimetry (DSC). The results indicated that cold deformation had great effect on aging precipitation behavior in the alloy. When the alloy was processed a pre-stretching deformation before aging, the precipitation of σ phase was restrained while the S′ phase (Al2CuMg) was promoted. And the nucleation sites played an important role on them.

Synthesis and characterization of pure and nanosized hydroxyapatite bioceramics

2017 ◽  
Vol 6 (2) ◽  
pp. 149-157 ◽  
Author(s):  
Aneela Anwar ◽  
Qudsia Kanwal ◽  
Samina Akbar ◽  
Aisha Munawar ◽  
Arjumand Durrani ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Calcium Nitrate ◽  
Temperature Stability ◽  
Molar Ratio ◽  
Calcium Nitrate Tetrahydrate ◽  
High Temperature Stability ◽  
X Ray ◽  
Transmission Electron ◽  
Nanosized Hydroxyapatite ◽  
Co Precipitation

AbstractSynthetic nanosized hydroxyapatite (HA) particles (<120 nm) were prepared using a co-precipitation technique by adopting two different routes – one from an aqueous solution of calcium nitrate tetrahydrate and diammonium hydrogen phosphate at pH 10 and the other by using calcium hydroxide and phosphoric acid as precursors at pH 8.5 and reaction temperature of 50°C. The lattice parameters of HA nanopowder were analogous to reference [Joint Committee on Powdered Diffraction Standards (JCPDS)] pattern no. 09-432. No decomposition of HA into other phases was observed even after heating at 1000°C in air for 1 h. This observation revealed the high-temperature stability of the HA nanopowder obtained using co-precipitation route. The effects of preliminary Ca/P molar ratio, precipitation, pH and temperature on the evolution of phase and crystallinity of the nanopowder were systematically examined and optimized. The product was evaluated by techniques such as X-ray-diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and Raman spectroscopy analyses. The chemical structural analysis of the as-prepared HA sample was performed using X-ray photoelectron spectroscopy (XPS). After heat treatment at 1000°C for 1 h and ageing for 15 h, the product was obtained as a phase-pure, highly crystalline HA nanorods.

Research on Microstructure Evolution of Spray Forming FVS0812 Alloy Varies with Temperature

2014 ◽  
Vol 543-547 ◽  
pp. 3729-3732
Author(s):  
Rong Hua Zhang ◽  
Biao Wu ◽  
Xiao Ping Zheng
Keyword(s):  
Electron Microscope ◽  
High Temperature ◽  
Energy Dispersive Spectrometer ◽  
Temperature Stability ◽  
Optical Microscope ◽  
Spray Forming ◽  
Effect Of Temperature ◽  
High Temperature Stability ◽  
Transmission Electron ◽  
Microstructure Of The Material

Heat-resistant FVS0812 alloys were prepared by spray forming technique. The effect of temperature on microstructure the alloys was studied by optical microscope (OM), transmission electron microscope (TEM) with energy dispersive spectrometer (EDS), differential scanning calorimeter (DSC) in this paper. The research results show that the microstructure of the material doesnt change obviously after being hold for 3 hours at 420°C temperature. When the temperature is over 420°C, the second coarse phases are found in the alloy. The studies on the microstructure of the alloy exposed at 400°C for 100 hours show that the alloy has excellent high temperature stability.

Inorganically filled carbon nanotubes: Synthesis and properties

2010 ◽  
Vol 82 (11) ◽  
pp. 2097-2109 ◽  
Author(s):  
Ujjal K. Gautam ◽  
Yoshio Bando ◽  
Pedro M. F. J. Costa ◽  
Xiaosheng Fang ◽  
Benjamin Dierre ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
High Temperature ◽  
Mechanical Response ◽  
Chemical Vapor ◽  
Temperature Stability ◽  
Inorganic Materials ◽  
High Temperature Stability ◽  
Heating Rates ◽  
Transmission Electron ◽  
Synthesis Strategy

Since the discovery of carbon nanotubes (CNTs) in 1991, widespread research has been carried out to understand their useful physical and electronic properties and also to explore their use in devices. CNTs have many unique properties such as tunable electrical resistance, mechanical robustness, and high thermal conductivity, which when combined with other inorganic materials such as phosphors or superconductors could lead to hetero-structures with diverse functionality. We have been able to obtain mass production of such materials wherein CNTs form core-shell heterostructures with metals, semiconductors, insulators, and even metal-semiconductor heterojunctions. The emerging strategy employs a high-temperature chemical vapor deposition (CVD) technique and high heating rates. Interestingly, due to their high temperature stability, CNTs can act as a nanoreactor for production of exotic materials inside it. In this article, we take ZnS-filled CNTs as an example to explain our synthesis strategy. We explore the optical behavior of these complex materials, analyzing both their luminescence and degradation upon exposure to an electron beam. In addition, the mechanical response of filled CNTs has been evaluated individually inside a transmission electron microscope fitted with an atomic force microscopy–transmission electron microscopy (AFM–TEM) sample holder. Many applications can be envisioned for these nanostructures ranging from nanothermometers to photo-protective storage and delivery devices.

Synthesis of AnataseTiO2 Having High Specific Surface Area from a Gel Precursor

2011 ◽  
Vol 485 ◽  
pp. 279-282
Author(s):  
Keiko Fukushi ◽  
Sae Nakajima ◽  
Kazuyoshi Uematsu ◽  
Tadashi Ishigaki ◽  
Kenji Toda ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Temperature Stability ◽  
High Specific Surface Area ◽  
High Temperature Stability ◽  
X Ray Diffraction ◽  
Dialysis Treatment ◽  
X Ray ◽  
Transmission Electron

Anatase TiO2 having high temperature stability and specific surface area was synthesized using a gel precursor in very mild conditions. The precursor gel was obtained by dialysis treatment of Na16Ti10O28–HNO3 solution. The samples were characterized by X-ray diffraction analysis, transmission electron microscopy, Brunner–Emmett–Teller method for specific surface area measurements, and thermogravimetric analysis.

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