Super High Temperature Research Articles

Non‐Volatile Glycerin Gel Enhanced by Sub‐5 nm Particles with Super Elasticity, Recoverability, and High Temperature Resistance

AbstractA gel material that can be applied to industry needs to fulfill two requirements: excellent mechanical properties and high temperature resistance. Previous research developed a hydrogel enhanced by sub‐5 nm particles, with excellent mechanical properties. While its application in the open environment is still limited by the volatilization of inner moisture, in this research, a non‐volatile gel (NV gel) enhanced by 5‐nm spherulites is manufactured. The NV gel remains stable after staying at 90 °C for 24 h. Meanwhile, being enhanced by sub‐5 nm nanospherulites, the NV gel shows good mechanical properties: with 200 ppm nanoparticle content, the tensile strength reaches 814 kPa and the compressive stress is 173.41 MPa at a recoverable 99% strain. The high temperature resistance is characterized by thermogravimetric analysis (TGA) and mechanical testing after thermal treatment. Transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, time of flight secondary ion mass spectrometry, and thermogravimetric analysis are used to evaluate the microstructure of NV gel. Possessing non‐volatile and good mechanical properties at the same time, this NV gel becomes very suitable for fulfilling the application requirement as an engineering material.

Research on Damage Mode of Super-high Temperature Composite Ceramic with Boride Base

Because of the space experiments of various countries, there are so many small pieces of debris in space, leading to the accident of spacecraft. Through AUTODYN software numerical analysis and SPH method, a numerical simulation study was carried out on the failure mode of the cylinder projectile impacting the double-layer ceramic target plate of aluminum alloy and boride base superhigh temperature composite ceramic at ultra high speed. The variation of perforation radius of the projectile against double target plate was obtained. The paper concludes that, in the failure mode of different mass projectiles striking double target plate, the total perforation radius of the second layer boride base superhigh temperature composite ceramic target increases first, then decreases and finally explodes.

The Interaction between Erosion Particle and Gas Stream in High Temperature Gas Burner Rig for Thermal Barrier Coatings

Abstract Thermal barrier coatings (TBCs) as a kind of temperature-resistance materials have been widely applied in super high temperature components in aircraft engines. However, TBCs are subjected to harsh service environment such as high temperature oxidation and erosion, which lead to the coating failure. It is important to investigate the effect of fire temperature, angle and velocity of particle on erosion to understand the failure mechanism. In this paper, the temperature and velocity distributions of erosion particles in high temperature gas burner rig are investigated by using the fluid–solid coupling method with the discrete random walk model. The results show that a non-uniform distribution of temperature appears in different positions of the central axis, and the temperature of particle is affected obviously by the gas stream and particle size. The trajectory of particles and velocity diagrams under different particle size are determined by coupling the continuous phase with the erosion particles.

Basic research of water jet cavitation toward the development of super high temperature and pressure bubble generation mechanism

Basic research of water jet cavitation toward the development of super high temperature and pressure bubble generation mechanism

High-efficiency copper-based electrocatalysts for oxygen electroreduction by heating metal-phthalocyanine at superhigh temperature

The highly efficient Cu-based ORR catalysts (Cu–N–C) were obtained by the pyrolysis of mesoporous KIT-6 silica-supported phthalocyanines at superhigh temperature (1000 °C). The prepared Cu–N–C catalyst was demonstrated as one of the best Cu-based electrocatalysts for ORR, with 0.82 V half-wave potential in 0.1 M KOH and 0.72 V half-wave potential in 0.1 M HClO4. It showed the competitive ORR activity to high-performance Fe- or Co-based carbon catalysts. Moreover, the ORR catalytic performance of Cu–N–C could be further enhanced by co-doping few Fe species (Fe–Cu–N–C) into the carbon framework. It revealed about 30 mV higher half-wave potential and better stability than Cu–N–C catalyst in both alkaline and acidic media. Cu–N–C and Fe–Cu–N–C electrocatalysts could be produced at a scale of over 15 g by facilely enlarging the amount of phthalocyanine precursors. The high-efficiency ORR performance and scalable synthesis of Cu–N–C and Fe–Cu–N–C catalysts enabled them to be the potential substitutes to Pt-based electrocatalyst for ORR.

Fabricating of high-performance functional graphene fibers for micro-capacitive energy storage.

Although graphene is a typical two dimensional materials, it has converted to multi-dimensional materials with many unique properties. As an example, the one dimensional graphene fiber is fabricated by utilizing ionic liquid as coagulation and functional diamines as cross-linkers to connect graphene oxide layers. The fibers show excellent mechanical properties and superior electrical performance. The tensile strength of the resultant fibers reaches ~729 MPa after a super high temperature thermal annealing treatment at 2800 °C. Additionally, quasi-solid-state flexible micro-capacitors are fabricated with promising result on energy storage. The device show a specific volumetric capacity as high as ~225 F/cm3 (measured at 103.5 mA cm−3 in a three-electrode cell), as well as a long cycle life of 2000 times. The initial results indicate that these fibers will be a good candidate to replace energy storage devices for miniaturized portable electronic applications.

Simulation of Thin Film Thermocouple for High Temperature Measurement Applicable to Missiles

<p>Thermocouples have been extensively used for the measurement of temperature since the advent of seebeck effect. Numerous sensors have been developed for temperature measurement, yet measurement of high temperature flowing fluid has been a challenging task. For the measurement of static temperature the measuring device should travel with the fluid at the same speed without disturbing the flow, which is quite unrealistic. So indirect determination of static temperature of flowing fluid is done by using thermocouple exposed into the flowing fluid. Other sensors available for high temperature measurement may lead to problems like resistance in the flow path of fluid which changes the structural dynamics. Thin film thermocouple (TFTC) based on W-W26Re for super high temperature measurement has been investigated which can be used in missiles for surface temperature measurement of nozzle and rocket interior surface. TFTC does not cause disruption in the flow path with maintaining structural integrity. The W-W26Re thermocouple offers advantage of higher seebeck coefficient at high temperature i.e. above 750 K, and usability in vacuum, inert and hydrogen atmosphere. Zirconia Fiber has been proposed as insulation protection material over thermocouple. Modelling and simulation of the TFTC for the temperature range 300 K - 2900 K has been presented. FEA model using PDE has been presented to implement heat equation, current balance quation, Gauss theorem and Neumann boundary condition. The expected voltage production on exposed temperature gradient has been studied.</p>

Mössbauer and XRD Studies of N0.6Cu0.2Zn0.2Ce(x)Fe2-xO4 Ferrites by Sol-Gel Auto-Combustion.

In this work, stoichiometric Ni0.6Cu0.2Zn0.2Ce(x)Fe2-xO4 ferrites with 0 ≤ x ≤ 0.85 have been prepared by Sol-Gel auto-combustion method and we have investigated the effect of impurity CeO2 phase to the microstructure and hyperfine magnetic field in spinel ferrite. The results of XRD patterns confirm that the average crystallite size of samples decreases with Ce3+ substitution increasing and the lattice parameters vary as a function of x content. 57Fe Mössbuaer spectra at room temperature for all samples confirm the [Fe(3+)-O2-Fe3+] super exchange interaction decrease due to cerium substitution. For low temperature auto-combustion samples it reveals one normal sextet line and one doublet line x ≤ 0.25, which show well-resolved ferromagnetic order. Lattice defects are determined and Mössbuaer spectrums vary from magnetic sextet to relaxation doublet at x > 0.45 due to a mass of CeO2 phase. In contrast, the Mössbuaer spectra for the samples sintered at 800 °C/3 h detect the secondary phase-Fe2O3 where the cation distribution occurs and it collapses to paramagnetic doublet (x ≥ 0.85). So Ce3+ substitution has its maximum limit values of super exchange interaction and high sintering temperature will affect this interaction. SEM shows the crystallite of the un-doped specimen sintered at 800 °C/3 h form well.

Transient Thermodynamic Behaviors of Super-high Temperature Gas-carrying Duct under Rapid Depressurization

The thermodynamic behaviors analysis for the transient flow of a compressible gas in a duct after an accidental rupture is undertaken based on the numerical simulation, which is performed by solving the coupled conservation equations, momentum equations and energy equations of an axisymmetric, transient, viscous flow. Applied in high temperature and high pressure atmosphere, super high temperature gas-carrying duct is constructed in structure as: thermal insulating media is installed between the liner tube and the outer wall of the hot gas duct. This structure is widely used in engineering such as the pipeline of the nuclear reactor, oil transportation and aerospace engineering. The pressure and the temperature, and their corresponding differences in insulating media and depressurization channel are calculated numerically. The results show that the depressurization rates in the insulting media and depressurization channel are much lower than that in the hot gas duct, and due to the insulting media, the max pressure differences vary with different amplitudes of depressurization. Compared the results with available experimental and numerical data conducted by Weber, they share the same trends though there are differences between the simulation and the experimental results, and the comparisons validate the effectiveness of the model and method.

New Mechanism of Saving Energy and Reducing Pollution in Burning Processing of Emulsified Oil

A new mechanism of saving energy and reducing pollution is brought forward by analyzing water characters in high temperature condition and all factors which bring saving energy and reducing pollution in the combustion process of emulsification oil. The theory shows that the reason of saving energy and reducing pollution is that emulsification oil can reduce surplus air ratio effectively in the combustion process. These reasons include that of improving the burning flame temperature, avoiding the local super-high temperature, decreasing the amount of NOX and the conversion of SO2 oxidize to SO3, strengthening the burning and heat transmission and reducing the soot of the flue gas.By this new theory, the reasons of saving energy and reducing pollution in the combustion process of emulsification gasoline, emulsification diesel oil, emulsification heavy oil and other slurry fuel of W/O or O/W can be well explained. At the same time, the new mechanism was well validated in the combustion process of hard asphalt water slurry.

A comparative study on life cycle assessment of micro and macro components

Micro manufacturing is an extremely demanding technological field where very special materials are used, extreme production condition like clean room, super high temperature, toxic chemicals, etc. are employed. Due to these facts, micro products can be environmentally damaging even after their smaller dimensional scale. So performing of LCA for micro products is equally important as it is for macro products. Keeping this motivation in mind, current paper systematically performs the LCA of a micro Socket used in hearing aids. The analysis makes a guide line about how to use the conventional knowledge about LCA and tools for the efficient LCA analysis of the micro parts. A comparative study is made in the paper by comparing two different sockets of hearing aid and it shows well how to make a comparative study for LCA when the manufacturer makes a new product to replace an old one. Another comparative study is made in the paper for micro and macro which shows that scaled up effect of the micro product compared to macro counterpart. The critical finding of this comparative study shows that the relative environmental damage done by micro product is higher than the macro product and that is confirmed by the net impact analysis. Finally, the LCA procedure presented in the paper, and the knowledge documented can be a valuable source of information for the researchers and scientists who work with the LCA of micro and macro products.

An optimized highly active and thermo-stable oxidation catalyst Pd/Ce–Zr–Y/Al2O3 calcined at superhigh temperature and used for C3H8 total oxidation

A series of supported catalysts Pd/Ce–Zr–Y/Al2O3 with different Y loadings (0%, 2%, 5%, 10% by weight) were prepared by ultrasonic-assisted impregnation, and employed for C3H8 total oxidation. It is found that these catalysts possess high catalytic activity and high thermal stability even after calcination at 1100°C, especially for the one promoted by 5% Y. In addition, this catalyst also exhibits best water-vapor resistance performance. The results of H2-TPR and XPS show that the addition of proper amount of Y to Pd/Ce–Zr/Al2O3 can enhance the interaction between Pd species and the support, thus increasing the dispersion of Pd species. The TEM, TPHD and CO pulse chemisorption results conformably reveal that the catalyst Pd/Ce–Zr–Y/Al2O3 containing 5% Y possesses the highest Pd dispersion as compared with others. However, excessive amounts of Y lead to remarkable decrease of BET surface area, lowering the dispersion of Pd species and weakening the interaction between Pd species and support; as a result, the catalyst exhibits lower oxidation activity. Combined with all the results of catalytic oxidation performance, water-vapor resistance performance and multiple characterizations, it is concluded that the Pd/Ce–Zr–Y/Al2O3 catalyst containing 5% Y possesses the greatest application potential for the catalytic removal of hydrocarbon pollutants released by engines during cold-start period.

Ir protective coatings for carbon structural materials

Ir coatings were deposited on the heat-treated C/C composites and graphite by double glow plasma. Microstructure and morphology of the coating and substrate were observed by SEM and TEM. The effect of the surface treatment for the carbon structural materials on the microstructure of the coating was investigated. Many large gaps and pores appeared on the surface of the substrates after heat treatment. The Ir coating did not fully covered on the surface of heat-treated C/C composite and graphite substrates because of the large gaps and pores on the surface of substrates. The Ir coating exhibited excellent ablation resistance at super-high temperature. After super-high temperature ablation, the coating kept the integrity, but the coating was weekly bonded to the substrates. Some microcracks and micropores appeared on the surface of as-ablated coating. The Ir coating would need thick enough to cover and fill the large microgaps and micropores on the surface of the heat-treated C/C and graphite substrates.

Preparation of High Heating Value Gas, High Quality Bio-Oil and Added Value Carbon Materials from Caragana Pyrolyzed via Super-High Temperature Steam

Caragana is an abundant plant as the feedstock of biomass energy in China. In this study, pyrolysis of Caragana in the presence of high temperature medium and characterization of products has been carried out. Evaluation of experimental results showed that faster devolatilization and char with increased surface area obtained in the presence of high temperature steam comparing to N2. Analysis of the obtained liquid revealed that the H/C and O/C ratios in the liquid are 1.5 and 0.16 respectively. Further more gas composition during high temperature steam pyrolysis differs from gas composition derived from N2 pyrolysis which indicates interaction of steam with vapors and solid species even at low treatment temperatures. The derived products’ yields and characteristics indicate possible exploitation of derived char as activate carbon precursor. Liquid fraction composition makes it suitable for exploitation as liquid fuel and/or chemical feedstock.

Growth of large crystallites of Co 37Ni 34Al 29 ferromagnetic shape memory alloys under super-high temperature gradient directional solidification

Large crystallites of Co 37Ni 34Al 29 ferromagnetic shape memory alloys were prepared by zone melting liquid metal cooling (ZMLMC) directional solidification; the effect of solidification rate and temperature gradient on the crystal microstructure and orientation was studied. Results show that at the solidification rate of 15 μm/s the alloy morphology exhibits coarse columnar crystal that is several millimeters in size and with worm-like γ′ precipitate, while at 150 μm/s it presents coarse dendrite surrounded by β+γ interdendritic eutectic. At the temperature gradient of 800 K/cm, a strong 〈1 1 0〉 oriented austenite crystal can be obtained at 15 μm/s and the preferred orientation turns into 〈1 0 0〉 direction as the solidification rate increases to 150 μm/s. The change of preferred orientation with solidification rate becomes more remarkable when the temperature gradient reaches 1200 K/cm.

Super Smooth Modification of Al2O3 Ceramic Substrate by High Temperature Glaze of CaO–Al2O3–SiO2 System

The rough surface of ceramic substrate is an obstacle for the scale down of line-width for thin film passive integrated devices (PID). In this paper, a modification method for Al2O3 ceramic substrate with super smooth in surface was proposed. Coating a layer of CaO–Al2O3–SiO2 (CAS) glass was performed to flat the rough surface of alumina substrate by sol–gel method. It was found that addition of 0.06% V2O5 can inhibit the recrystallization of the glaze. The root-mean-square (RMS) roughness of the glazed substrates reached a surprising flatness as small as 0.5 nm, and its melting temperature is higher than 1300 °C. This substrate with super flatness and high temperature endurance may be promising for high performance thin film devices.

Microstructure Characterization of Alumina/Carbon Nanotubes Composite Coating

Alumina/carbon nanotubes (Al2O3/CNTs) composite coating was synthesized by plasma spray employing mixtures of Al2O3-coated CNTs and nano-sized α-Al2O3 at atmosphere. This coating was characterized for the microstructure and the composition by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM), thermo gravimetric analysis (TG), differential scanning calorimetry analysis (DSC) and scanning electron microscopy (SEM). The results show that the thickness of the coating is about 0.5mm and the constituent elements were changed to α-Al2O3, CNTs and γ-Al2O3 duo to the superhigh temperature during the plasma spray process. The great mass of the mixtures were melted well and the CNTs were dispersed uniformly in the melted ceramic. The oxidation resistance and the microwave absorption properties were discussed simply to describe the functions of the composite coating.

(Invited) Advanced (Millisecond) Annealing in Silicon Based Semiconductor Manufacturing

Rapid thermal annealing has taken a new turn at the beginning of this century with the advent of term "advanced annealing". Although the annealing techniques are a few decades old, they have not seen many applications in the semiconductor industry until recently, primarily due to the complexity of the tools involved and their mechanical interaction with silicon wafers. The tolerance for dopant diffusion has reduced significantly from one ITRS node to next. Advanced anneals rely primarily on achieving super-high temperatures (>1100oC) in very short periods of time (milliseconds). These anneals provide the relevant thermal budget for dopant activation processes with minimal diffusion, thus making them attractive. However, as process integration has become more complex additional challenges are encountered by super-high temperature anneals at the recent technology nodes. Additionally, these annealing techniques impart severe mechanical stress on wafers by heating the wafers at rates >10^5 oC/s. This paper will focus on simulation and experimental verification of stress that is experienced by silicon wafers during a millisecond annealing process

The propagation and deposition of fast muons in dense DT mixture

The propagation of the fast muon population mainly due to collisional effect in a dense deuterium–tritium (DT for short) mixture is investigated and analysed within the framework of the relativistic Fokker–Planck equation. Without the approximation that the muons propagate straightly in the DT mixture, the muon penetration length, the straggling length, and the mean transverse dispersion radius are calculated for different initial energies, and especially for different densities of the densely compressed DT mixture in our suggested muon-driven fast ignition (FI). Unlike laser-driven FI requiring super-high temperature, muons can catalyze DT fusion at lower temperatures and may generate an ignition sparkle before the self-heating fusion follows. Our calculation is important for the feasibility and the experimental study of muon-driven FI.

Microstructural characteristics and formation mechanism of direct laser-sintered Cu-based alloys reinforced with Ni particles

Direct metal laser sintering (DMLS) was used to consolidate Cu-based alloy powder (Cu–10Sn and Cu–8.4P) reinforced with Ni particles. Phases, microstructures, compositions, and mechanical properties of laser-sintered part were studied. It showed that particle bonding was through a liquid phase sintering mechanism involving the complete melting of matrix alloy powder and the non-melting of cores of Ni reinforcing particles. A significant smoothening of Ni particles occurred in the liquid and the dissolved Ni element alloyed with Cu element to form CuNi solid solution, leading to a coherent particle/matrix interface after solidification. The dendrites of matrix alloys developed directionally and the primary dendritic spacing was highly refined to ∼1.5 μm, due to laser-induced super high temperature gradient and solidification rate. The additive P element acted as a localized deoxidizer to prevent the sintering system from oxidation by formation of CuPO 3, thereby enhancing liquid–solid wettability and resultant sintering activity. A high densification level of 95.2% theoretical density was obtained after sintering. The fracture surface of laser-sintered part was mainly featured by a strong ductile type of fracture. The dynamic nanohardness of Ni reinforcing phase and Cu-based matrix alloys reached 1.82 GPa and 0.99–1.35 GPa, respectively.