Phase Transformation of Nb in Carburized Zone of 25Cr35NiNb+MA Alloy After Service

Abstract25Cr35NiNb+MA alloy is widely used in ethylene pyrolysis furnace tube, the highest service temperature can be 1100°C, and has high resistance to creep and carburization. Ethylene pyrolysis furnace tube will suffer carburizing during service, which lead to phase transformation. Phase transformation of 25Cr35NiNb+MA heat-resistant ethylene pyrolysis furnace tube was investigated after service and the Nb transition during service was discussed. The phase transformation of ethylene pyrolysis furnace tube was characterized with field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive spectrum (EDS). Results reveal that the microstructure of as-cast 25Cr35NiNb+MA alloy contains NbC carbides on the dendrite boundaries. During service at high temperature, the NbC carbides transform to blocky G-phase (Ni16Nb6Si7) between M23C6 and matrix. As the carburizing process occurs, the blocky G-phase (Ni16Nb6Si7) gradually transforms to granular NbC, and distribute at the center of chromium carbide. The granular NbC will improve resistance of creep

INTERACTION OF WHEY PROTEIN WITH MODIFIED STAINLESS STEEL SURFACES

Modified stainless steel surfaces were fouled with whey protein solutions to study the deposition mechanisms and the effects of surface modification. Stainless steel samples were coated with diamond-like carbon (DLC) and titanium nitride (TiN). These surfaces are expected to present different surface chemistries to stainless steel in terms of their functional groups and hydrophobic or hydrophilic nature. Thus, it is expected that foulant-surface interactions will differ for the various fouled surfaces. The substrates were exposed to a flowing whey protein solution in a fouling rig designed to achieve laminar flow. X-ray Photoelectron Spectroscopy (XPS) was used to study the initial protein-surface interactions of samples fouled for 1 minute at 75°C. Ellipsometry was used to study the fouling and cleaning performance of samples fouled at 75°C and 85°C for up to 30 minutes followed by ultrasonic caustic cleaning of selected samples. XPS showed the presence of similar protein functional groups on all fouled surfaces. The bonding mechanisms during fouling of DLC is different to the stainless steel and TiN surfaces. The peptide link played a more active role at the deposit-surface interface for the non-polar DLC surface, while it was less significant for the two polar surfaces. Ellipsometry revealed that for the three surfaces, fouling increased in the order DL

Impacts of potential future sea level rise on the North branch of the Changjiang river estuary: Quantifying the saline water intrusion in the dry season

The phenomenon of global sea level rise (SLR) is undeniable; the 4th IPCC report summaries that the\ud average rise rate of global is 1.8 mm/y since 1961. It is widely taken for granted that SLR will have a severe impact on\ud saline water intrusion processes in estuarine areas. In this paper, by using a two-dimensional hydrodynamic model\ud (MIKE21) and SLR scenarios of 0.5m, 1m and 2m, the impacts of potential future SLR on the North Branch of the\ud Changjiang River Estuary are evaluated by quantifying salinity changes in the dry season. The field data of tidal levels,\ud flow velocities and salinities are employed to validate the model, and the computed results match the observed values\ud well, which indicates that the validated model can provide reliable performances in reproducing the hydrodynamic and\ud saline water intrusion processes in the Changjiang River Estuary, then this validated numerical model was run with\ud present sea level as well as 0.5m, 1m and 2 m SLR scenarios in the dry season respectively. The computations show\ud that: i)the amplification of tidal levels in the upper reach of the South Branch is greater than that in the upper reach of\ud the North Branch with SLR; ii)the ebb and flood discharges in the upper cross-section of the North Branch both respond\ud to SLR with a significant increase trend, with the ebb flow split ratio of the North Branch increasing from 3.8% to\ud 10.3% in 2m SLR scenario; iii)the salinity in the North Branch presents a decrease trend with SLR, and the decreasing\ud extent in the upper reach is 11.4%-33.4%, which is obvious greater than that in the middle and lower reaches.\ud Consequently, it can be concluded that SLR enhances the ebb hydrodynamics and alleviates the saline water intrusion in\ud the North Branch

THE THERMO-HYDRODYNAMICS OF A CONCENTRIC OHMIC HEATER FOR PROCESSING DAIRY FLUIDS

The thermo-hydraulic performance of a 300W concentric annular ohmic heater was investigated. To minimize possible electrochemical reactions and corrosion, a higher frequency was applied and factors of field strength and frequency were studied. 2D computer simulation solving momentum, thermal and electrical energy was performed using the FlexPDE software. A good agreement between experimental and analytical analysis of static heating was obtained. There were significant differences between calculated and measured wall temperature near the entrance. The calculated outlet temperature was however in reasonable agreement with the experiment value

Novel species of Calonectria associated with Eucalyptus leaf blight in Southeast China

Leaf blight caused by Calonectria spp. is an important disease occurring on Eucalyptus trees grown in plantations of Southeast Asia. Symptoms of leaf blight caused by Calonectria spp. have recently been observed in commercial Eucalyptus plantations in FuJian Province in Southeast China. The aim of this study was to identify these Calonectria spp. employing morphological characteristics, DNA sequence comparisons for the β-tubulin, histone H3 and translation elongation factor-1α gene regions and sexual compatibility. Four Calonectria spp. were identified, including Ca. pauciramosa and three novel taxa described here as Ca. crousiana, Ca. fujianensis and Ca. pseudocolhounii. Inoculation tests showed that all four Calonectria spp. found in this study were pathogenic on two different E. urophylla × E. grandis hybrid clones, commercially utilised in eucalypt plantations in China

Comparative Study on Magnetic Properties and Microstructure of As-prepared and Alternating Current Joule Annealed Wires

AbstractX-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), magnetic measurement including impedance measurement were used for investigating the microstructure and magnetic properties of as-prepared and alternating current Joule annealed (ACJA) Co-rich amorphous microwires for potential sensor applications. Experimental results indicated that as-cast and ACJA wires both were amorphous characteristic, while ACJA wire has an enhanced local ordering degree of atom arrangement. There was a transform of magnetic properties after ACJA treatment, namely increasing coercivity, maximum magnetic permeability and saturation magnetization, resulting from the coactions of magnetic anisotropy and magnetic moment exchange coupling. Moreover, ACJA treatment can drastically improve the GMI property of melt-extracted wires. At 5MHz, the maximum GMI ratio [ΔZ/Z0]max of ACJA wire increases to 205.93%, which is nearly 4.1 times of 50.62% for as-cast wire, and the field response sensitivity ξmax of ACJA wire increases to 463.70%/Oe by more than 2 times of 212.15%/Oe for as-cast wire. From sensor application perspective, the sensor applied frequency range (SAFR) of ACJA wire is 3MHz-7MHz (the better working frequency is at 5MHz). It can therefore be concluded that the ACJA wire (60mA, 480s, 50Hz) has better GMI and magnetic properties, is more suitable for potential magnetic sensor applications working at low-frequency and relatively high-working-magnetic field

Properties and Performance of Two Wide Field of View Cherenkov/Fluorescence Telescope Array Prototypes

A wide field of view Cherenkov/fluorescence telescope array is one of the main components of the Large High Altitude Air Shower Observatory project. To serve as Cherenkov and fluorescence detectors, a flexible and mobile design is adopted for easy reconfiguring of the telescope array. Two prototype telescopes have been constructed and successfully run at the site of the ARGO-YBJ experiment in Tibet. The features and performance of the telescopes are presented

STRUCTURAL CHARACTERISTICS OF BATCH PROCESSED AGRO-WASTE FIBRES

The characterisation of agro-wastes fibres from Nigeria using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) has been done. Fibres extracted from groundnut shell, coconut husk, rice husk, palm fruit bunch and palm fruit stalk are processed using two novel cellulose fibre production methods developed by the authors. Cellulose apparent crystallinity calculated using the deconvolution of the diffractometer trace shows that the amorphous portion of cellulose was permeable to hydrolysis yielding high crystallinity after treatment. All diffratograms show typical cellulose structure with well-defined 110, 200 and 040 peaks. Palm fruit fibres had the highest 200 crystalline cellulose peaks compared to others and it is an indication of rich cellulose content. Surface examination of the resulting fibres using SEM indicates the presence of regular cellulose network structure with some agglomerated laminated layer of thin leaves of cellulose microfibrils. The surfaces were relatively smooth indicating the removal of hemicellulose, lignin and pectin

Constitutive Equations and Processing Maps for 49MnVS3 Non-Quenched and Tempered Steel

Flow stress variations of 49MnVS3 non-quenched and tempered steel are studied in isothermal compression tests on a Gleeble-1500D thermal simulated test machine at a deformation temperatures of 950, 1000, 1150, and 1200° C, and strain rates of 0.1, 1, 5, and 10 s⁻¹, with obtaining the strain hardening exponent n and deformation activation energy Q of the alloy. Thus, the constitutive equations and processing maps of compression flow behavior for 49MnVS3 non-quenched and tempered steel at high temperatures are established. It shows that the peak stress is shownto significantly reduced with a decrease in the strain rate and increase in deformation temperature when the alloy deforms at high temperature, and the deformation activation energy is 350.98 kJ/mol. When the true strain of 49MnVS3 non-quenched and microalloyed steel high-temperature deformation is 0.5, the optimum process parameters of the alloy are determined to be 1150–1200° C for the deformation temperature and 2–10 s⁻¹ for the strain rate, based on the criterion that the process parameters of higher power dissipation efficiency values should be chosen in the dynamic recrystallization region as the best processing technology.Изменение напряжения течения незакаленной и закаленной стали 49MnVS3 исследовали путем проведения испытаний на изотермическое сжатие на установке Gleeble-1500D, моделирующей высокотемпературные условия, при температурах деформации 950, 1000, 1150, 1200° C и скоростях деформации 0,1; 1; 5 и 10 c⁻¹ с показателем степени деформационного упрочнения n и значением энергии активации деформации сплава Q. Установлены определяющие уравнения и схемы обработки компрессионного режима течения для незакаленной и закаленной стали 49MnVS3 при высокой температуре. Анализ уравнений показал, что максимальное значение напряжения значительно уменьшается при снижении скорости деформации и повышении температуры деформации, если сплав подвергается деформации при высокой температуре, а значение энергии активации деформации составляет 350,98 кДж/моль. Если значения истинной деформации незакаленной стали 49MnVS3 и высокотемпературной деформации микролегированной стали составляют 0,5, то оптимальные параметры процесса обработки сплава определяются при температуре деформирования 1150…1200° C и скорости деформации 2…10 c⁻¹ на основе критерия, который способствует отбору параметров с более высокой эффективностью рассеивания мощности в области динамической рекристаллизации в качестве оптимальной технологии обработки.Зміну напруження течії незагартованої і загартованої сталі 49MnVS3 досліджували шляхом проведення випробувань на ізотермічний стиск на установці Gleeble-1500D, що моделює високотемпературні умови, за температур деформації 950, 1000, 1150, 1200° C та швидкості деформації 0,1; 1; 5 і 10 c⁻¹ із показником степеня деформаційного зміцнення n і значенням енергії активації деформації сплаву Q. Установлено визначальні рівняння і схеми обробки компресійного режиму течії для незагартованої і загартованої сталі 49MnVS3 за високої температури. Аналіз рівнянь показав, що максимальне значення напруження значно зменшується зі зниженням швидкості деформації і підвищенні температури деформації, якщо сплав зазнає деформації за високої температури, а значення енергії активації деформації дорівнює 350,98 кДж/моль. Якщо значення істинної деформації незагартованої сталі 49MnVS3 і високотемпературної деформації мікролегованої сталі дорівнюють 0,5, то оптимальні параметри процесу обробки сплаву визначаються за температури деформування 1150...1200° C і швидкості деформації 2...10 c⁻¹ на основі критерію, який сприяє відбору параметрів із більш високою ефективністю розсіяння потужності в області динамічної рекристалізації як оптимальної технології обробки

Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and νp nucleosynthesis processes

© 2018 The Authors. Published by Elsevier B.V. This manuscript is made available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence (CC BY-NC-ND 4.0). For further details please see: https://creativecommons.org/licenses/by-nc-nd/4.0/Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of 82Zr and 84Nb were measured for the first time with an uncertainty of ∼10 keV, and the masses of 79Y, 81Zr, and 83Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low α separation energies for neutron-deficient Mo and Tc isotopes, making the formation of Zr–Nb cycle in the rp-process unlikely. The new proton separation energy of 83Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus 84Sr relative to the neutron-deficient molybdenum isotopes in the previous νp-process simulations.Peer reviewe