Articoli di riviste: "Secondary precipitation"

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Gu, Yi Jie, Yong Hu, Hong Quan Liu, Heng Hui Zhou, Zhen Guo e Zu Wang Hu. "Synthesis the Precursor of LiNi_0.5Mn_0.5O₂ via an Improved Carbonate Co-Precipitation". Advanced Materials Research 233-235 (maggio 2011): 32–35. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.32.

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Spherical Ni0.5Mn0.5CO3 is synthesized via carbonate co-precipitation method which uses NH4HCO3 as the precipitator. However, obvious agglomerate of secondary particles occurs when NH4HCO3 is used as the precipitator. The agglomerate particles can result in inferior physical characteristic. An improved carbonate co-precipitation which used NH4HCO3 doped with different proportion of NaOH as a new precipitator is tested in our study. Observed by SEM and Mastersizer, spherical morphology with narrow particle size distribution is synthesized with the proportion of NaOH reaches 10%. The element line analysis by Electron Probe Micro-analyzer shows symmetrical distributions of Ni and Mn elements via the improved carbonate co-precipitation.

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Wysocka, Izabela. "Wastewater parameters after the process of phosphorus compounds removal by the metal dissolution method in comparison with precipitation and electrocoagulation methods". Ochrona Srodowiska i Zasobów Naturalnych 28, n. 1 (1 marzo 2017): 8–13. http://dx.doi.org/10.1515/oszn-2017-0001.

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Abstract Precipitation methods are commonly used for removing phosphorus compounds from wastewater. Chemical precipitation method, based on adding iron, aluminium or calcium salts to the treated wastewater, is often used. Another possible way of precipitating phosphates is metal dissolution method, which is presented in this paper. The main difference between these two methods is how the phosphate precipitating ions are introduced to the wastewater. This paper discusses advantages and disadvantages of the metal dissolution method in comparison with traditional precipitation methods. Differences in the secondary contamination of treated wastewater by iron ions, conductivity, total alkalinity and pH correction process; the use of recyclable wastes; and energy consumption are discussed.

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Yang, Song, Kwo-Sen Kuo e Eric A. Smith. "Persistent Nature of Secondary Diurnal Modes of Precipitation over Oceanic and Continental Regimes". Journal of Climate 21, n. 16 (15 agosto 2008): 4115–31. http://dx.doi.org/10.1175/2008jcli2140.1.

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Abstract This investigation seeks a better understanding of the assorted mechanisms controlling the global distribution of diurnal precipitation variability based on the use of the Tropical Rainfall Measuring Mission (TRMM) microwave radiometer and radar data. The horizontal distributions of precipitation’s diurnal cycle are derived from 8 yr of TRMM Microwave Imager (TMI) and Precipitation Radar (PR) measurements involving three TRMM standard rain retrieval algorithms; the resultant distributions are analyzed at various spatiotemporal scales. The results reveal both the prominent and expected late-evening (LE) to early-morning (EM) precipitation maxima over oceans and the counterpart prominent and expected mid- to late-afternoon (MLA) maxima over continents. Moreover, and not generally recognized, the results reveal a widespread distribution of secondary maxima, which generally mirror their counterpart regime’s behavior, occurring over both oceans and continents. That is, many ocean regions exhibit clear-cut secondary MLA precipitation maxima, while many continental regions exhibit just as evident secondary LE–EM maxima. This investigation is the first comprehensive study of these globally prevalent secondary maxima and their widespread nature, a type of study only made possible when the analysis procedure is applied to a high-quality global-scale precipitation dataset. The characteristics of the secondary maxima are mapped and described on global grids using an innovative clock-face format, while a current study that is to be published at a later date provides physically based explanations of the seasonal regional distributions of the secondary maxima. In addition to a primary “explicit” maxima identification scheme, a secondary “Fourier decomposition” maxima identification scheme is used as a cross-check to examine the amplitude and phase properties of the multimodal maxima. Accordingly, the advantages and ambiguities resulting from the use of a Fourier harmonic analysis are investigated.

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Shin, Byung-Hyun, Dohyung Kim, Sanghyup Park, Myungwon Hwang, Junghyun Park e Wonsub Chung. "Precipitation condition and effect of volume fraction on corrosion properties of secondary phase on casted super-duplex stainless steel UNS S32750". Anti-Corrosion Methods and Materials 66, n. 1 (7 gennaio 2019): 61–66. http://dx.doi.org/10.1108/acmm-06-2018-1958.

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Purpose The secondary phase decreased the corrosion resistance because of the segregation of Cr and Mo. Therefore, this paper aims to study the precipitation condition and the effect of secondary phase with volume fraction on corrosion behavior. Design/methodology/approach Secondary phase precipitated approximately from 375°C to 975°C because of saturated Cr and Mo at grain boundary by growth of austenite. Therefore, heat treatment from 800°C to 1,300°C was applied to start the precipitation of the secondary phase. Findings The secondary phase is precipitated at 1,020°C because of segregation by heterogeneous austenite. The growth of austenite at 1,000°C needs the time to saturate the Cr and Mo at grain boundary. When the volume fraction of austenite is 56 per cent (14 min at 1,000°C), the secondary phase is precipitated with grain boundary of austenite. The secondary phase increased the current density (corrosion rate) and decreased the passivation. That is checked to the critical pitting temperature (CPT) curves. The 1 per cent volume fraction of secondary phase decreased CPT to 60°C from 71°C. Research limitations/implications The precipitation of secondary phase not wants anyone. Casted super-duplex stainless steel (SDSS) of big size precipitates the secondary phase. This study worked the precipitation condition and the suppression conditions of secondary phase. Social implications Manufacturers need precipitation condition to make high-performance SDSS. Originality/value The corrosion resistance of SDSS is hard the optimization because SDSS is dual-phase stainless steel. The precipitation of the secondary phase must be controlled to optimize of the corrosion resistance of SDSS. Anyone not studied the precipitation condition of secondary phase and the effect of secondary phase with volume fraction on corrosion behavior of SDSS.

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Ryu, Young-Hee, Seung-Ki Min e Christoph Knote. "Role of Upwind Precipitation in Transboundary Pollution and Secondary Aerosol Formation: A Case Study during the KORUS-AQ Field Campaign". Journal of Applied Meteorology and Climatology 61, n. 2 (febbraio 2022): 159–74. http://dx.doi.org/10.1175/jamc-d-21-0162.1.

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Abstract Clouds and precipitation play critical roles in wet removal of aerosols and soluble gases in the atmosphere, and hence their accurate prediction largely influences accurate prediction of air pollutants. In this study, the impacts of clouds and precipitation on wet scavenging and long-range transboundary transport of pollutants are examined during the 2016 Korea–United States Air Quality (KORUS-AQ) field campaign using the Weather Research and Forecasting Model coupled with chemistry. Two simulations—one in which atmospheric moisture is constrained and one in which it is not—are performed and evaluated against surface and airborne observations. The simulation with moisture constraints is found to better reproduce precipitation as well as surface PM2.5, whereas the areal extent and amount of precipitation are overpredicted in the simulation without moisture constraints. As a results of overpredicted clouds and precipitation and consequently overpredicted wet scavenging, PM2.5 concentration is generally underpredicted across the model domain in the simulation without moisture constraints. The effects are significant not only in the precipitating region (upwind region, southern China in this study) but also in the downwind region (South Korea) where no precipitation is observed. The difference in upwind precipitation by 77% on average between the two simulations leads to the difference in PM2.5 by ∼39% both in the upwind and downwind regions. The transboundary transport of aerosol precursors, especially nitric acid, has a considerable impact on ammonium-nitrate aerosol formation in the ammonia-rich downwind region. This study highlights that skillful prediction of atmospheric moisture can have ultimate potential to skillful prediction of aerosols across regions.

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Lumley, R. N., I. J. Polmear e A. J. Morton. "Interrupted aging and secondary precipitation in aluminium alloys". Materials Science and Technology 19, n. 11 (novembre 2003): 1483–90. http://dx.doi.org/10.1179/026708303225008112.

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Yang, F. M., X. F. Sun, W. Zhang, Y. P. Kang, H. R. Guan e Z. Q. Hu. "Secondary M6C precipitation in K40S cobalt-base alloy". Materials Letters 49, n. 3-4 (giugno 2001): 160–64. http://dx.doi.org/10.1016/s0167-577x(00)00361-x.

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Macchi, C. E., A. Somoza, A. Dupasquier e I. J. Polmear. "Secondary precipitation in Al–Zn–Mg–(Ag) alloys". Acta Materialia 51, n. 17 (ottobre 2003): 5151–58. http://dx.doi.org/10.1016/s1359-6454(03)00364-1.

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Li, Y. H., J. D. Fambrough e C. T. Montgomery. "Mathematical Modeling of Secondary Precipitation From Sandstone Acidizing". SPE Journal 3, n. 04 (1 dicembre 1998): 393–401. http://dx.doi.org/10.2118/53001-pa.

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Holba, V. "Secondary structure of periodic precipitation patterns in gelatin". Colloid & Polymer Science 267, n. 5 (maggio 1989): 456–59. http://dx.doi.org/10.1007/bf01410193.

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Balabin, Yuriy, Aleksey Germanenko, Boris Gvozdevsky, Evgeniy Maurchev e Evgeniya Mikhalko. "Precipitation-related increase events of the electromagnetic component of secondary cosmic rays: Spectral analysis". Solar-Terrestrial Physics 9, n. 2 (29 giugno 2023): 37–47. http://dx.doi.org/10.12737/stp-92202305.

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We report the measurement results of differential spectra of electromagnetic radiation in the range 0.1–4 MeV, which occurs in the atmosphere as a component of secondary cosmic rays. Spectral monitoring was performed using a spectrometer based on the Nai (TL) crystal in 2022–2023. The main purpose of the measurements was to determine spectral characteristics of the electromagnetic radiation during increase events, when the electromagnetic radiation flux from the atmosphere rises by tens of percent with respect to the background level. From a thorough analysis of the spectra of many dozens of events, we have drawn a conclusion that although the lines of natural radionuclides are present on the spectra and contribute their share, their total contribution to the increase events is ~0.1 of the total energy supplied during an increase. We unambiguously conclude that the effect of increasing electromagnetic radiation during precipitation is not due to the presence of radionuclides in precipitation.

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Palomo, C., N. Rodríguez, E. Iglesias, J. Nieto, J. Cobos e J. Quiñones. "Incorporation of REE into Secondary Phase Studtite." MRS Proceedings 1665 (2014): 71–77. http://dx.doi.org/10.1557/opl.2014.630.

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ABSTRACTThe formation of uranyl peroxide phases was identified as a corrosion product of spent fuel by Hanson et al [1]. The subsequent analysis of this phase showed that metastudtite retained 241Am, 237Np and 239Pu [2]. In this study, the retention of radionuclide Pu4+ and An3+, released from the spent fuel matrix into studtite structure, has been evaluated by the precipitation of studtite from uranyl dissolution with variable concentrations of REE (Th, Nd, Sm and Eu). Three different precipitation conditions parameters were studied: media of synthesis, time of synthesis and REE concentration. Synthesized phases were characterized by XRD and the cell parameter was calculated. The REE incorporation was determined by ICP-MS analysis. The results showed that studtite could incorporate 63% of Th in solution during its precipitation. Changes in the “a” cell parameter were identified. The results suggest that studtite coprecipitated with REE could play a role as a limiting for the REE mobility.

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Svetozarević, Jelena. "Precipitation changes in the hills of the upper Nišava river basin (1961-2020)". Pirotski zbornik, n. 47 (2022): 119–31. http://dx.doi.org/10.5937/pirotzbor2247119s.

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The study represents a report on the monthly, seasonal and annual amounts of precipitation, extremely dry and extremely rainy periods. The paper analyzes two 30-year periods from 1961-1990. and from 1991-2020. Data from the four meteorological stations in the upper part of the Nišava basin (Babušnica, Bela Palanka, Pirot and Dimitrovgrad) have ben used, three of which are in the Nišava basin and one of which (Babušnica) is in the immediate vicinity of the basin. The main goal of the paper is to provide an overview of the change in the precipitation in Pirot district at the end of the 21st century. The district is mainly an agricultural area and rainfall is very important for its development. The continental type of pluviometric regime is represented in the district of Pirot. The analysis of annual precipitation shows that the area of Pirot records a decrease in the annual sum of the precipitation with the increase in Dimitrovgrad, while Bela Palanka and Babušnca have no significant changes. In the first period that was considered by the conducted analysis (1961-1990), the secondary maximum precipitations occur on the average during the month of November and for the period of 1991-2020, the secondary maximum precipitation is a month earlier, in October, except for the station in Bela Palanka.

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Semenova, Irina P., e Alexander Medvedev. "Influence of Severe Plastic Deformation and Ageing on the Microstructure and Mechanical Properties of β-Alloy Ti-6.8Mo-4.5Fe-1.5Al". Materials Science Forum 667-669 (dicembre 2010): 731–36. http://dx.doi.org/10.4028/www.scientific.net/msf.667-669.731.

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This work presents the possibility of strength enhancement in the -alloy Ti-6.8Mo-4.5Fe-1.5Al via equal channel angular pressing at room temperature without precipitation of a secondary -phase. Influence of the initial structure of the alloy and ageing temperature on the density of precipitations and dimensions of the secondary -phase is revealed. It has been stated that combination of the solid solution treatment with the subsequent ECAP processing and final ageing is an effective way to achieve superior strength and ductility.

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Rožnovská, Gabriela, Vlastimil Vodárek e Zdeněk Kuboň. "Precipitation of Secondary Phases in a Supermartensitic 13Cr6Ni2.5MoTi Steel during Heat Treatment". Materials Science Forum 891 (marzo 2017): 161–66. http://dx.doi.org/10.4028/www.scientific.net/msf.891.161.

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The balance between strength and toughness of supermartensitic steels can be controlled by heat treatment parameters. Quality heat treatment usually consists of quenching and single or double tempering above the Ac1 temperature. Such a treatment results in stabilization of reverted austenite in the tempered martensite. Tempering can also be accompanied by intensive precipitation processes, especially in high alloyed grades. A detailed TEM characterisation of precipitation processes in a 13Cr6Ni2.5MoTi supermartensitic steel proved that single tempering at temperatures of 600°C and 690°C was accompanied by precipitation of three minor phases: MX (TiX), M23C6 and Laves phase (Fe2Mo type). Precipitation processes were more intensive at 690°C. Volume fractions of MX and M23C6 phases were low. Laves phase precipitation was intensive and particles of this minor phase grew fast. However, thermodynamic calculations using the Thermocalc software suggest that Laves phase is not an equilibrium phase in the steel under consideration.

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Lilensten, J., e M. Galand. "Proton-electron precipitation effects on the electron production and density above EISCAT (Tromsø) and ESR". Annales Geophysicae 16, n. 10 (31 ottobre 1998): 1299–307. http://dx.doi.org/10.1007/s00585-998-1299-8.

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Abstract. The suprathermal particles, electrons and protons, coming from the Sun and precipitating into the high-latitude atmosphere are an energy source for the Earth's ionosphere. They interact with the ambient thermal gas through inelastic and elastic collisions. Most of the physical quantities perturbed by the precipitation, such as the electron production rate, may be evaluated by solving the stationary Boltzmann transport equation, which yields the particle fluxes as a function of altitude, energy, and pitch angle. This equation has been solved for the three different suprathermal species (electrons, protons and hydrogen atoms). We first compare the results of our theoretical code to a coordinated DMSP/EISCAT experiment, and to another approach. Then, we show the effects that pure proton precipitation may have on the ionosphere, through primary and secondary ionization. Finally, we compare the effects of proton precipitation and electron precipitation in some selected cases above EISCAT (Tromsø) and ESR.Key words. Ionosphere (auroral ionosphere; ionosphere-magnetosphere interactions; particle precipitation).

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Gultepe, I., A. J. Heymsfield, P. R. Field e D. Axisa. "Ice-Phase Precipitation". Meteorological Monographs 58 (1 gennaio 2017): 6.1–6.36. http://dx.doi.org/10.1175/amsmonographs-d-16-0013.1.

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AbstractIce-phase precipitation occurs at Earth’s surface and may include various types of pristine crystals, rimed crystals, freezing droplets, secondary crystals, aggregates, graupel, hail, or combinations of any of these. Formation of ice-phase precipitation is directly related to environmental and cloud meteorological parameters that include available moisture, temperature, and three-dimensional wind speed and turbulence, as well as processes related to nucleation, cooling rate, and microphysics. Cloud microphysical parameters in the numerical models are resolved based on various processes such as nucleation, mixing, collision and coalescence, accretion, riming, secondary ice particle generation, turbulence, and cooling processes. These processes are usually parameterized based on assumed particle size distributions and ice crystal microphysical parameters such as mass, size, and number and mass density. Microphysical algorithms in the numerical models are developed based on their need for applications. Observations of ice-phase precipitation are performed using in situ and remote sensing platforms, including radars and satellite-based systems. Because of the low density of snow particles with small ice water content, their measurements and predictions at the surface can include large uncertainties. Wind and turbulence affecting collection efficiency of the sensors, calibration issues, and sensitivity of ground-based in situ observations of snow are important challenges to assessing the snow precipitation. This chapter’s goals are to provide an overview for accurately measuring and predicting ice-phase precipitation. The processes within and below cloud that affect falling snow, as well as the known sources of error that affect understanding and prediction of these processes, are discussed.

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Chaus, Alexander S., e F. I. Rudnickii. "Diffusion and Secondary Carbide Precipitation in High-Speed Steels". Defect and Diffusion Forum 297-301 (aprile 2010): 1071–76. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.1071.

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Besides primary carbides, so-called secondary carbides are usually observed in high-speed steel (HSS) microstructure, which precipitate from the oversaturated solid solution upon its cooling. Some of the secondary carbides precipitate from an oversaturated austenite at cooling during solidification or quenching, in both cases, in the form of the relatively big particles in the bulk of a matrix. Considerably finer secondary carbides precipitate in martensitic condition during tempering inducing secondary hardening in HSSs. In general, secondary carbides of both types have obvious effect on the fracture mode of HSSs. The precipitation of secondary carbides in HSSs in solidified and heat-treated conditions has been investigated. The microstructures of HSSs have been examined using light and electron microscopy (both scanning and transmission), X-ray diffraction analysis, and energy dispersive X-ray spectrometry. Results indicate that diffusion of both carbon and alloying elements plays an important role in the secondary carbide precipitation in HSSs.

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Yin, M., D. D. Risanti, Jiang Hua Chen e Sybrand van der Zwaag. "A TEP Study on the Microstructural Development in AA2024 during Interrupted Ageing". Advanced Materials Research 89-91 (gennaio 2010): 669–74. http://dx.doi.org/10.4028/www.scientific.net/amr.89-91.669.

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This work utilizes thermoelectric power (TEP) measurement to track secondary precipitation during the interrupted ageing cycle for AA2024 alloys as well as the subsequent re-ageing cycle. Clear evidences of secondary precipitation were observed which affect the further precipitation sequence during re-ageing. The TEM results confirm that S and S” phases co-exist upon re-ageing.

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Baumann, Carsten, Markus Rapp e Antti Kero. "Secondary electron emission from meteoric smoke particles inside the polar ionosphere". Annales Geophysicae 34, n. 6 (23 giugno 2016): 573–80. http://dx.doi.org/10.5194/angeo-34-573-2016.

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Abstract. The charging by secondary electron emission (SEE) from particles is known as a significant charging process in astrophysical plasmas. This work aims at evaluating the significance of SEE for charging of meteoric smoke particles (MSPs) in the Earth's polar atmosphere. Here, the atmosphere is subject to a bombardment of energetic electrons from the magnetosphere (and partly the sun). We employ the SEE formalism to MSPs in the upper mesosphere using electron precipitation fluxes for three different precipitation strengths. In addition, we address the possible effect of tertiary electron emission (TEE) from MSPs induced by atmospheric secondary electrons for one precipitation case. The SEE and TEE rates from MSPs of different sizes are compared to plasma attachment and photodetachment and photoionization rates of MSPs. The needed concentration of electrons and ions have been modeled with the Sodankylä Ion and Neutral Chemistry (SIC) model with included electron precipitation spectra as an additional ionization source. We find that secondary electron emission from MSPs is not a relevant charging mechanism for MSPs. The electron attachment to MSPs and photodetachment of negatively charged MSPs are the most important processes also during energetic electron precipitation.

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Krähenmann, S., e B. Ahrens. "On daily interpolation of precipitation backed with secondary information". Advances in Science and Research 4, n. 1 (29 marzo 2010): 29–35. http://dx.doi.org/10.5194/asr-4-29-2010.

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Abstract. This paper investigates the potential impact of secondary information on rainfall mapping applying Ordinary Kriging. Secondary information tested is a natural area indicator, which is a combination of topographic features and weather conditions. Cross validation shows that secondary information only marginally improves the final mapping, indicating that a one-day accumulation time is possibly too short.

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OISHI, Yoshiki, Shintaro MIYAMOTO, Hiroshi MINAGAWA e Makoto HISADA. "STUDY ON PRECIPITATION MECHANISM OF ETTRINGITE AS SECONDARY MINERAL". Cement Science and Concrete Technology 71, n. 1 (2017): 117–24. http://dx.doi.org/10.14250/cement.71.117.

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Buha, J., R. N. Lumley, A. G. Crosky e K. Hono. "Secondary precipitation in an Al–Mg–Si–Cu alloy". Acta Materialia 55, n. 9 (maggio 2007): 3015–24. http://dx.doi.org/10.1016/j.actamat.2007.01.006.

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Shin, Byung-Hyun, Dohyung Kim e Jang-Hee Yoon. "Crystallization of Secondary Phase on Super-Duplex Stainless Steel SAF2507: Advanced Li-Ion Battery Case Materials". Crystals 14, n. 4 (18 aprile 2024): 378. http://dx.doi.org/10.3390/cryst14040378.

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The demand for Li-ion batteries has increased because of their extensive use in vehicles and portable electronic devices. This increasing demand implies greater interaction between batteries and humans, making safety a paramount concern. Although traditional batteries are fabricated using Al, recent efforts to enhance safety have led to the adoption of AISI304. The strength and corrosion resistance of AISI304 are greater than those of Al; however, issues such as stress-induced phase transformation and low high-temperature strength have been observed during processing. Duplex stainless steel SAF2507, which is characterized by a dual-phase structure consisting of austenite and ferrite, exhibits excellent strength and corrosion resistance. Although SAF2507 demonstrated outstanding high-temperature strength up to 700 °C, it precipitated a secondary phase. The precipitation of this secondary phase, believed to be caused by the precipitation of the carbides of Cr and Mo, has been extensively studied. Research on the precipitation of the secondary phase near 1000 °C has been conducted owing to the annealing temperature (1100 °C) of the SAF2507 solution. The secondary phase precipitates at approximately 1000 °C because of slow cooling rates. However, few studies have been conducted on the precipitation of the secondary phase at approximately 700 °C. This study analyzed the precipitation behavior of the secondary phase at 700 °C when SAF2507 was applied and assessed its safety during heat generation in Li-ion batteries. The precipitation behavior was analyzed using field emission scanning electron microscopy for morphology, energy-dispersive X-ray spectroscopy for composition, and X-ray diffraction for phase identification.

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Chen, Yong, Xin Long Zhang, Ji Lai Lu, Wei Jing Liu e Yong Tu. "Accelerated Seeded Precipitation Pre-Treatment for the Improvement of Reverse Osmosis Membrane". Applied Mechanics and Materials 477-478 (dicembre 2013): 1365–68. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.1365.

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The research on accelerated seeded precipitation pre-treatment for the improvement of secondary RO membrane was investigated. The influences of seed type, initial pH and seed dosage on accelerated seeded precipitation were studied. SEM images for the secondary RO membrane were also discussed.

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Shin, Byung-Hyun, Seongjun Kim, Jinyong Park, Jung-Woo Ok, Dohyung Kim e Jang-Hee Yoon. "Study of Precipitated Secondary Phase at 700 °C on the Electrochemical Properties of Super Duplex Stainless Steel AISI2507: Advanced High-Temperature Safety of a Lithium-Ion Battery Case". Materials 17, n. 9 (25 aprile 2024): 2009. http://dx.doi.org/10.3390/ma17092009.

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Super duplex stainless steel (SDSS) is a suitable structural material for various engineering applications due to its outstanding strength and corrosion resistance. In particular, its high-temperature strength can enhance the safety of electronic products and cars. SDSS AISI2507, known for its excellent strength and high corrosion resistance, was analyzed for its microstructure and electrochemical behavior at the ignition temperature of Li-ion batteries, 700 °C. At 700 °C, AISI2507 exhibited secondary phase precipitation values of 1% and 8% after 5 and 10 h, respectively. Secondary phase precipitation was initiated by the expansion of austenite, forming sigma, chi, and CrN phases. The electrochemical behavior varied with the fraction of secondary phases. Secondary phase precipitation reduced the potential (From −0.25 V to −0.31 V) and increased the current density (From 8 × 10−6 A/cm2 to 3 × 10−6 A/cm2) owing to galvanic corrosion by sigma and chi. As the fraction of secondary phases increased (From 0.0% to 8.1%), the open circuit potential decreased (From −0.25 V to −0.32 V). Secondary phase precipitation is a crucial factor in reducing the corrosion resistance of SDSS AISI2507 and occurs after 1 h of exposure at 700 °C.

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Jia, Wenxiong, Hui Xiong, Guofeng Zhu, Yang Shi, Zhiyuan Zhang, Le Yang, Miaomiao Zhang e Fuhua Zhang. "Influence of Sub-Cloud Secondary Evaporation and Moisture Sources on Stable Isotopes of Precipitation in Shiyang River Basin, Northwest China". Water 14, n. 17 (30 agosto 2022): 2700. http://dx.doi.org/10.3390/w14172700.

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Fractionation of stable isotopes in precipitation runs through the water cycle, and deuterium excess is a second-order parameter linking water-stable oxygen and hydrogen isotopes. It is strongly influenced by under-cloud evaporation in unsaturated air, especially in arid climates. Based on the improved Stewart model, this study used 670 precipitation stable isotope data and measured meteorological element data from 11 sampling points from January 2018 to September 2019 to verify the existence of sub-cloud secondary evaporation in the Shiyang river basin and quantitatively calculate the intensity of sub-cloud secondary evaporation and its influence on precipitation stable isotopes. The study used the vapor flux and the improved Lagrangian model to track the moisture source of precipitation and analyze the influence of the moisture source of different paths on the stable isotopes of precipitation. Therefore, this study is helpful to understand the evapotranspiration loss mechanism and recharge mechanism of moisture in the watershed. The results showed that there is sub-cloud secondary evaporation in the Shiyang River Basin, and from the seasonal scale, the sub-cloud secondary evaporation is stronger in spring and summer, but weaker in autumn and winter, which makes heavy isotopes enriched in spring and summer and depleted in autumn and winter. From the perspective of spatial distribution, the sub-cloud secondary evaporation is stronger in the midstream and downstream of the Shiyang river, resulting in more enrichment of heavy isotopes. In the vertical direction, the sub-cloud secondary evaporation at 850–700 hPa is the strongest, which enriches the heavy isotope in this layer and reduces the deuterium excess. In addition, the main moisture source of precipitation in the Shiyang River Basin is the westerly air mass, and the mid and high-latitude land sources contribute more moisture to the precipitation. However, the supply of the sea source is very limited, which makes the deuterium excess of precipitation higher and does not show regional consistency and seasonality well.

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Koutsoukis, T., Abdelkrim Redjaïmia e G. Fourlaris. "Characterization of Precipitation Sequences in Superaustenitic Stainless Steels". Solid State Phenomena 172-174 (giugno 2011): 493–98. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.493.

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Superaustenitic stainless steels exhibit excellent corrosion resistance, at a wide variety of exposure temperatures, especially in chloride containing environments, coupled with desirable mechanical properties. Previous studies have shown that these steels are prone to precipitation of secondary phases, such as sigma phase (σ), chi phase (χ), Laves-phase, carbides, nitrides or secondary austenite, when exposed at elevated temperatures, directly affecting their mechanical properties and corrosion behaviour. A detailed study of the effect of isothermal ageing on the microstructure of S32654 (Fe-24Cr-21Ni-7Mo-0.5N-0.013C) and S31254 (Fe-20Cr-18Ni-6Mo-0.2N-0.012C) superaustenitic stainless steels was carried out. Samples were aged within the temperature range of 650οC to 950οC for times up to 3000 h. Following ageing, precipitation of secondary phases was clearly observed with precipitates varying in volume fraction, size, shape and spatial distribution. Several secondary phases were identified via transmission electron microscopy (TEM) and electron diffraction (ED). The orientation relationships between the austenitic matrix and the secondary phases were identified. Interaction and also phase transformation among different types of precipitates, such as between precipitates and the austenitic matrix were observed and an attempt of understanding these phase transformations was carried out.

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29

Zhou, Ben Zhi, Xiao Ming Wang, Yong Hui Cao, Wei Jian Kong e Yi Lin Tang. "Water and Soil Conservation Characteristics for Two Typical Subtropical Forests in Southeast China". Advanced Materials Research 518-523 (maggio 2012): 4827–31. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.4827.

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Moso bamboo and natural secondary forests are the typical forest types in subtropical area in China. With field observation at the Qiangjiangyuan Forest Ecosystem Research Station. the effect of the two typical forests was compared on soil and water conservation and their difference was quantified. The results showed that: (1) The runoff coefficients for moso bamboo and natural broad-leaved secondary forest go up with increase of precipitation. (2) Natural broad-leaved secondary and moso bamboo forests both are pretty good in preservation of water source and water and soil conservation. The former is better than the latter. moso bamboo forest is over 90% higher than natural broadleaved secondary in runoff generation, and three times higher in sediment yield. (3) Runoff for two forest types has a significant correlation with precipitation outside the forest. Total runoff has a significant linear relation with precipitation, and the runoff coefficient has a logarithm correlation with precipitation.

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30

Calliari, Irene, Marco Breda, Claudio Gennari, Luca Pezzato, Massimo Pellizzari e Andrea Zambon. "Investigation on Solid-State Phase Transformations in a 2510 Duplex Stainless Steel Grade". Metals 10, n. 7 (17 luglio 2020): 967. http://dx.doi.org/10.3390/met10070967.

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Duplex and Super Duplex Stainless Steels are very prone to secondary phases formation related to ferrite decomposition at high temperatures. In the present paper the results on secondary phase precipitation in a 2510 Duplex Stainless Steel, heat-treated in the temperature range 850–1050 °C for 3–30 min are presented. The precipitation starts at grain boundaries with a consistent ferrite transformation for very short times. The noses of the Time–Temperature–Precipitation (TTP) curves are at 1000 °C for σ-phase and at 900 °C for χ-phase, respectively. The precipitation sequence involves a partial transformation of χ into σ, as previously evidenced in 2205 and 2507 grades. Furthermore, the experimental data were compared to the results of Thermo-Calc calculations. Understanding and ability to predict phase stability in 2510 duplex stainless steel is a key factor to design optimal welding processes that avoid any secondary phase precipitation in the weld bead as well as in the heat-affected zone.

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31

Sosa, Matías, Alejandro Sepulveda Buitrago e Alberto Carlos Picasso. "STUDY OF M23C6 PRECIPITATION IN A 45Ni-35Cr-Nb ALLOY". Acta Metallurgica Slovaca 25, n. 3 (25 settembre 2019): 180. http://dx.doi.org/10.12776/ams.v25i3.1312.

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The 45Ni-35Cr-Nb alloy, commonly known as ET45 micro, produced in the form of centrifugally cast tubes, was studied by means of optical microscopy after aging treatments at 1073 and 1173 K for different times. A description of M23C6 secondary carbides precipitation phenomenon was made as a function of time. The purpose of carrying out a kinetic study of the precipitation of this phase is to be able to calculate the activation energy required for secondary precipitation. This allows to infer what is the mechanism associated with it. Analysis after using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) model showed that secondary carbide precipitation occurs in a single stage. It was found that this phenomenon, which is assisted by diffusion, has an activation energy of 196 kJ/mol. This value would indicate that the diffusion of Cr atoms in the austenitic matrix is the phenomenon that dominates the precipitation of the M23C6 secondary carbide.

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32

Woodley, William L., e Daniel Rosenfeld. "Secondary Seeding as a Means of Propagating Seeding Effects in Space and Time". Journal of Weather Modification 34, n. 1 (26 gennaio 2018): 31–38. http://dx.doi.org/10.54782/jwm.v34i1.232.

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Secondary seeding, whereby unseeded clouds ingest ice particles from clouds that earlier had received direct glaciogenic (e.g., silver iodide) treatment, is hypothesized to be a possible additional mechanism for the propagation of seeding effects in space and for time. The ingested ice particles, after experiencing some growth in the donor cloud, act to glaciate the receptor cloud during its active growth phase and provide it precipitation embryos. These embryos give the new cloud a head-start on precipitation development as they grow further as graupel to precipitation size in the updraft laden with high quantities of supercooled cloud water. This enhancement of precipitation-forming processes is postulated to be strongest in microphysically continental clouds in which natural and seeding-induced primary glaciation and hydrometeor growth are slow. A case study is presented to illustrate these processes.

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33

Lumley, Roger N., J. Buha, Ian J. Polmear, A. J. Morton e A. Crosky. "Secondary Precipitation in Aluminium Alloys & Its Role in Modern Heat Treatment". Materials Science Forum 519-521 (luglio 2006): 283–90. http://dx.doi.org/10.4028/www.scientific.net/msf.519-521.283.

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This paper reviews some of the practical outcomes of exploiting secondary precipitation during the heat treatment of aluminium alloys and discusses current understanding of this phenomenon. Recent studies have utilised the techniques of positron annihilation spectroscopy (PAS), 3D atom probe (3DAP) as well as the more traditional transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) to investigate early precipitation events that occur during secondary ageing at low temperatures (~20-65°C). This work has confirmed that clustering and GP zone formation can modify the nature and distribution of precipitates that form when ageing is subsequently resumed at more elevated temperatures. Prospects for achieving further improvements in heat treatment schedules and alloy compositions to take greater advantage of secondary precipitation are also considered.

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34

Kim, Yu-Mi, Se-Weon Choi, Young-Chan Kim, Chang-Seok Kang e Sung-kil Hong. "Influence of the Precipitation of Secondary Phase on the Thermal Diffusivity Change of Al-Mg2Si Alloys". Applied Sciences 8, n. 11 (24 ottobre 2018): 2039. http://dx.doi.org/10.3390/app8112039.

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Al-Si-Mg alloys are investigated to determine the relationship between changes in the thermal diffusivity and precipitation behavior of the Mg2Si phase with various contents of Mg2Si and aging treatment conditions. The samples were solid solution-treated and then quenched with water (80 °C). Aging treatments were implemented at temperatures ranging from 180 to 240 °C for 5 h. The precipitation behavior of Mg2Si was observed using a heat flow curve using differential scanning calorimetry analysis. The thermal diffusivity of Al-Mg2Si alloy was affected by the precipitation of the Mg2Si phase, particularly in the meta-stable β phase. In the temperature range of precipitation occurrence, the thermal diffusivity of the alloy increased with the temperature when the precipitation of the meta-stable β phase of the sample was incomplete. However, at the same temperature, the samples in which precipitation had completed did not have any increased thermal diffusivity. The thermal diffusivity of the samples decreased when the meta-stable Mg2Si phase had dissolved in the matrix. The precipitation and dissolution of Mg2Si mainly affected the variation of thermal diffusivity in Al-Si-Mg. In contrast, the stable Mg2Si phase was not affected by changes in thermal diffusivity at a high temperature.

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35

Shi, Wei Ning, Hai Fei Zhou e Xin Fang Zhang. "Rapid Dissolution of Secondary Phase in Cold-Rolling Al-Cu-Mg Alloy by Electropulsing Treatment". Materials Science Forum 990 (maggio 2020): 3–7. http://dx.doi.org/10.4028/www.scientific.net/msf.990.3.

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The Al-Cu-Mg alloy is a precipitation-strengthening alloy, which is traditionally dissolving lots of secondary phase and precipitating in subsequent aging process, thus having been applied to aerospace and automobile industry due to its low density and high strength. However, the high temperature and long operating time needed for the dissolution of secondary phase consume numerous energy. In this work, rapid dissolution of secondary phase in cold-rolling Al-Cu-Mg alloy was achieved by coupling treatment of thermal field and pulsed electric current. The energy consumption for dissolving secondary phasewas reduced from 495°C operating 1h to 450°C operating several minutes. Therefore, the coupling treatment of thermal field and pulsed electric current significantly improves the dissolving rate and decreases the energy consumption.

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36

de Alencar Pires, Sandro, Marcos Flavio de Campos, C. J. Marcelo e Carlos Roberto Xavier. "Secondary Austenite Precipitation during the Welding of Duplex Stainless Steels". Materials Science Forum 869 (agosto 2016): 562–66. http://dx.doi.org/10.4028/www.scientific.net/msf.869.562.

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In this work a multipass welding procedure was carried out on a 2205 Duplex stainless steels (DDS) plate. Due to the reheating cycle caused by the adopted procedure, it has favored the precipitation of secondary austenite at the weldment microstructure, besides of encouraging the grain growth at the heat affected zone (HAZ).

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37

Mesquita, Rafael Agnelli, Celso Antonio Barbosa, E. Valencia Morales e H. J. Kestenbach. "Secondary Carbide Precipitation in Low Silicon Hot Work Tool Steels". Materials Science Forum 636-637 (gennaio 2010): 612–17. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.612.

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A reduction from 1.0 to 0.3%Si has recently been shown to improve mechanical properties of H11-type hot work tool steels. The present paper shows that an important improvement in toughness can be explained by the effect of Si content on the precipitation sequence of secondary carbides during tempering after quenching. Carbide particle distributions were observed and identified by electron microscopy, allowing to relate the effect of Si on mechanical properties directly to its effect on cementite and subsequent alloy carbide formation during high temperature tempering.

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38

Smoukov, Stoyan K., István Lagzi e Bartosz A. Grzybowski. "Independence of Primary and Secondary Structures in Periodic Precipitation Patterns". Journal of Physical Chemistry Letters 2, n. 4 (31 gennaio 2011): 345–49. http://dx.doi.org/10.1021/jz101679t.

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39

Lissarrague, Matías Humberto Sosa, Alfredo Juan, César Lanz, Bruno La Rocca e Alberto Picasso. "KINETIC ANALYSIS OF SECONDARY PRECIPITATION IN A HP40-Nb ALLOY". Acta Metallurgica Slovaca 25, n. 4 (18 dicembre 2019): 223. http://dx.doi.org/10.12776/ams.v25i4.1361.

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Abstract (sommario):

The HP40-Nb heat resistant alloy (35Ni-25Cr-Nb) was analysed by means of optical microscopy after aging treatments at 1073 and 1173 K for different times, in order to apply the classic Johnson – Mehl - Avrami – Kolmogorov kinetic model (JMAK), and thus calculate the activation energy of secondary M23C6 precipitation, which occurs during thermal aging. The relevance of this theoretical analysis is to infer the mechanism that controls the nucleation and growth of M23C6 secondary carbides, since the amount and morphology of these phase influences the mechanical properties as well as the corrosion resistance in service. After performing the kinetic analysis using the JMAK model, the activation energy was found to be 208 kJ/mol, which would indicate that the secondary precipitation in this alloy is controlled by the Cr-diffusion phenomenon along the austenitic matrix.

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40

Jiang, W. H., X. D. Yao, H. R. Guan, Z. Q. Hu e W. H. Jiang. "Secondary carbide precipitation in a directionally solified cobalt-base superalloy". Metallurgical and Materials Transactions A 30, n. 3 (marzo 1999): 513–20. http://dx.doi.org/10.1007/s11661-999-0043-7.

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41

Jönsson, Jörgen, Julia Jönsson e Lars Lövgren. "Precipitation of secondary Fe(III) minerals from acid mine drainage". Applied Geochemistry 21, n. 3 (marzo 2006): 437–45. http://dx.doi.org/10.1016/j.apgeochem.2005.12.008.

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42

Германенко, Алексей, Aleksey Germanenko, Юрий Балабин, Yuriy Balabin, Борис Гвоздевский, Boris Gvozdevsky, Леонид Щур e Leonid Schur. "Nature of gamma radiation variations during atmospheric precipitations". Solar-Terrestrial Physics 2, n. 1 (1 giugno 2016): 78–88. http://dx.doi.org/10.12737/19880.

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The Polar Geophysical Institute has developed a complex facility for continuously monitoring various components of secondary cosmic rays. Gamma radiation during precipitation events has been found to increase the year round regardless of the season. A series of experiments has revealed that there is no precipitation pollution by any natural or artificial radionuclides. Radiation spectrum does not have any characteristic lines of elements. We propose a mechanism providing a satisfactory description for this phenomenon.

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43

Patrick, C. J., D. J. McGarvey, J. H. Larson, W. F. Cross, D. C. Allen, A. C. Benke, T. Brey et al. "Precipitation and temperature drive continental-scale patterns in stream invertebrate production". Science Advances 5, n. 4 (aprile 2019): eaav2348. http://dx.doi.org/10.1126/sciadv.aav2348.

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Secondary production, the growth of new heterotrophic biomass, is a key process in aquatic and terrestrial ecosystems that has been carefully measured in many flowing water ecosystems. We combine structural equation modeling with the first worldwide dataset on annual secondary production of stream invertebrate communities to reveal core pathways linking air temperature and precipitation to secondary production. In the United States, where the most extensive set of secondary production estimates and covariate data were available, we show that precipitation-mediated, low–stream flow events have a strong negative effect on secondary production. At larger scales (United States, Europe, Central America, and Pacific), we demonstrate the significance of a positive two-step pathway from air to water temperature to increasing secondary production. Our results provide insights into the potential effects of climate change on secondary production and demonstrate a modeling framework that can be applied across ecosystems.

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44

Sullivan, Sylvia C., Christian Barthlott, Jonathan Crosier, Ilya Zhukov, Athanasios Nenes e Corinna Hoose. "The effect of secondary ice production parameterization on the simulation of a cold frontal rainband". Atmospheric Chemistry and Physics 18, n. 22 (21 novembre 2018): 16461–80. http://dx.doi.org/10.5194/acp-18-16461-2018.

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Abstract. Secondary ice production via processes like rime splintering, frozen droplet shattering, and breakup upon ice hydrometeor collision have been proposed to explain discrepancies between in-cloud ice crystal and ice-nucleating particle numbers. To understand the impact of this additional ice crystal generation on surface precipitation, we present one of the first studies to implement frozen droplet shattering and ice–ice collisional breakup parameterizations in a mesoscale model. We simulate a cold frontal rainband from the Aerosol Properties, PRocesses, And InfluenceS on the Earth's Climate campaign and investigate the impact of the new parameterizations on the simulated ice crystal number concentrations (ICNC) and precipitation. Near the convective regions of the rainband, contributions to ICNC can be as large from secondary production as from primary nucleation, but ICNCs greater than 50 L−1 remain underestimated by the model. The addition of the secondary production parameterizations also clearly intensifies the differences in both accumulated precipitation and precipitation rate between the convective towers and non-convective gap regions. We suggest, then, that secondary ice production parameterizations be included in large-scale models on the basis of large hydrometeor concentration and convective activity criteria.

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45

Moras, Charly A., Lennart T. Bach, Tyler Cyronak, Renaud Joannes-Boyau e Kai G. Schulz. "Ocean alkalinity enhancement – avoiding runaway CaCO₃ precipitation during quick and hydrated lime dissolution". Biogeosciences 19, n. 15 (1 agosto 2022): 3537–57. http://dx.doi.org/10.5194/bg-19-3537-2022.

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Abstract. Ocean alkalinity enhancement (OAE) is a method that can remove carbon dioxide (CO2) from the atmosphere and counteract ocean acidification through the dissolution of alkaline minerals. Currently, critical knowledge gaps exist regarding the dissolution of different minerals suitable for OAE in natural seawater. Of particular importance is to understand how much alkaline mineral can be dissolved before secondary precipitation of calcium carbonate (CaCO3) occurs, since secondary CaCO3 precipitation reduces the atmospheric CO2 uptake potential of OAE. Using two types of mineral proposed for OAE, quick lime (CaO) and hydrated lime (Ca(OH)2), we show that both (<63 µm of diameter) dissolved in seawater within a few hours. No CaCO3 precipitation occurred at a saturation state (ΩA) of ∼5, but CaCO3 precipitation in the form of aragonite occurred above an ΩA value of 7. This limit is lower than expected for typical pseudo-homogeneous precipitation, i.e. in the presence of colloids and organic matter. Secondary precipitation at low ΩA (∼ 7) was the result of heterogeneous precipitation onto mineral surfaces, most likely onto the added CaO and Ca(OH)2 particles. Most importantly, runaway CaCO3 precipitation was observed, a condition where significantly more total alkalinity (TA) was removed than initially added. Such runaway precipitation could reduce the OAE CO2 uptake efficiency from ∼ 0.8 mol of CO2 per mole of added TA down to 0.1 mol of CO2 per mole of TA. Runaway precipitation appears to be avoidable by dilution below the critical ΩA threshold of 5, ideally within hours of the mineral additions to minimise initial CaCO3 precipitation. Finally, OAE simulations suggest that for the same ΩA threshold, the amount of TA that can be added to seawater would be more than 3 times higher at 5 ∘C than at 30 ∘C. The maximum TA addition could also be increased by equilibrating the seawater to atmospheric CO2 levels (i.e. to a pCO2 of ∼ 416 µatm) during addition. This would allow for more TA to be added in seawater without inducing CaCO3 precipitation, using OAE at its CO2 removal potential.

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46

Pezzato, Luca, Mattia Lago, Katya Brunelli, Marco Breda, Enrico Piva e Irene Calliari. "Effect of Secondary Phases Precipitation on Corrosion Resistance of Duplex Stainless Steels". Materials Science Forum 879 (novembre 2016): 1495–500. http://dx.doi.org/10.4028/www.scientific.net/msf.879.1495.

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Duplex Stainless steels (DSS) are biphasic austeno-ferritic steels in which the best combination of mechanical and corrosion resistance properties is achieved for almost equal volume fraction of the phases. These steels are classified according to their pitting corrosion resistance, assessed by the PREN index (Pitting Resistance Equivalent Number) which, although qualitatively, is widely employed as comparison. The present work is aimed to study the pitting resistance of four DSS grades (SAF 2101, 2304, 2205 and 2507) in the as-received condition and after isothermal aging in the critical range 750°C-900°C, to highlight the effect of secondary phases precipitation on the corrosion behavior. The materials were potentiodynamically tested in artificial seawater (pH7) at room temperature and the corresponding Critical Pitting Temperatures (CPT) were determined according to ASTM G150. Secondary phase precipitation mainly affected the lean duplex grades whereas the high-alloyed DSS were more stable even if large precipitation occurred.

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47

Salem, Islam, Mohamed Kamal El-Fawkhry, Ahmed A. Abdel-Khalek, M. H. Khedr e Taha Mattar. "Exo-Inoculant Modification of Secondary Phase Precipitation in H13 Tool Steel". Key Engineering Materials 835 (marzo 2020): 13–21. http://dx.doi.org/10.4028/www.scientific.net/kem.835.13.

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Secondary phase carbides in term of type and morphology are considered as the most challenge facing the applications of hot work tool steel. AISI H13 tool steel is one of the most applicable hot work tool steel grades. M23C6, M6C and MC are the common secondary carbides that are forming throughout the martensite matrix of H13 tool steel. In this research, nanoinoculant silicon nitride was added to the molten H13 tool steel to act as an inoculant for the secondary carbide categories through ladle treatment process. By using OM and SEM, it was observed that nanoinoculant has the great impact in the nucleation of secondary carbides into fine shape, in particular M23C6 type. In addition, mechanical tests proved that the nucleation of secondary carbides promotes the mechanical properties of hot work H13 tool steel to its ultimate. Impact toughness of the inoculated H13 tool steel was observed with higher value than that was done at the ordinary H13 tool steel. At the meantime, wear resistance of inoculated H13 tool steel was multiplied two times higher than as delivered H13 tool steel.

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48

Lawson, R. Paul, Roelof Bruintjes, Sarah Woods e Colin Gurganus. "Coalescence and Secondary Ice Development in Cumulus Congestus Clouds". Journal of the Atmospheric Sciences 79, n. 4 (aprile 2022): 953–72. http://dx.doi.org/10.1175/jas-d-21-0188.1.

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Abstract Understanding ice development in cumulus congestus (CuCg) clouds, which are ubiquitous globally, is critical for improving our knowledge of cloud physics, precipitation and climate prediction models. Results presented here are representative of data collected in 1008 penetrations of moderate to strong updrafts in CuCg clouds by five research aircraft in six geographic locations. The results show that CuCg with warm (∼23°C) cloud-base temperatures, such as in tropical marine environments, experience a strong collision–coalescence process. Development of coalescence is also correlated with drop effective radius >∼12 to 14 μm in diameter. Increasing the cloud-base drop concentration with diameters from 15 to 35 μm and decreasing the drop concentration < 15 μm appears to enhance coalescence. While the boundary layer aerosol population is not a determinate factor in development of coalescence in most tropical marine environments, its impact on coalescence is not yet fully determined. Some supercooled large drops generated via coalescence fracture when freezing, producing a secondary ice process (SIP) with production of copious small ice particles that naturally seed the cloud. The SIP produces an avalanche effect, freezing the majority of supercooled liquid water before fresh updrafts reach the −16°C level. Conversely, CuCg with cloud-base temperatures ≤ ∼8°C develop significant concentrations of ice particles at colder temperatures, so that small supercooled water drops are lofted to higher elevations before freezing. Recirculation of ice in downdrafts at the edges of updrafts appears to be the primary mechanism for development of precipitation in CuCg with colder cloud-base temperatures. Significance Statement Cumulus congestus clouds occur globally and account for a significant amount of precipitation in the tropics. The physics underlying the warm rain process and development of ice in cumulus congestus clouds are fundamental to a better understanding of precipitation formation. The collected data show that the strength of collision–coalescence is strongly influenced by cloud-base temperature, and that millimeter-diameter supercooled cloud drops will form in convective clouds with base temperatures warmer than 20°C. When supercooled large drops form, there is a secondary ice process that rapidly freezes the large majority of supercooled cloud water before updrafts reach the −16°C level. Incorporating results from the observations will improve cloud-resolving and climate prediction models.

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Dedekind, Zane, Annika Lauber, Sylvaine Ferrachat e Ulrike Lohmann. "Sensitivity of precipitation formation to secondary ice production in winter orographic mixed-phase clouds". Atmospheric Chemistry and Physics 21, n. 19 (12 ottobre 2021): 15115–34. http://dx.doi.org/10.5194/acp-21-15115-2021.

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Abstract. The discrepancy between the observed concentration of ice nucleating particles (INPs) and the ice crystal number concentration (ICNC) remains unresolved and limits our understanding of ice formation and, hence, precipitation amount, location and intensity. Enhanced ice formation through secondary ice production (SIP) could account for this discrepancy. Here, in a region over the eastern Swiss Alps, we perform sensitivity studies of additional simulated SIP processes on precipitation formation and surface precipitation intensity. The SIP processes considered include rime splintering, droplet shattering during freezing and breakup through ice–graupel collisions. We simulated the passage of a cold front at Gotschnagrat, a peak at 2281 m a.s.l. (above sea level), on 7 March 2019 with the Consortium for Small-scale Modeling (COSMO), at a 1 km horizontal grid spacing, as part of the RACLETS (Role of Aerosols and CLouds Enhanced by Topography and Snow) field campaign in the Davos region in Switzerland. The largest simulated difference in the ICNC at the surface originated from the breakup simulations. Indeed, breakup caused a 1 to 3 orders of magnitude increase in the ICNC compared to SIP from rime splintering or without SIP processes in the control simulation. The ICNCs from the collisional breakup simulations at Gotschnagrat were in best agreement with the ICNCs measured on a gondola near the surface. However, these simulations were not able to reproduce the ice crystal habits near the surface. Enhanced ICNCs from collisional breakup reduced localized regions of higher precipitation and, thereby, improved the model performance in terms of surface precipitation over the domain.

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Makhmutov, V. S., E. A. Maurchev, G. A. Bazilevskaya e I. A. Mironova. "Development of a Method for Recovery of the Energy Spectra of Precipitating Electrons from the Data of Measurements in the Atmosphere". Геомагнетизм и аэрономия 63, n. 5 (1 settembre 2023): 638–43. http://dx.doi.org/10.31857/s0016794023600564.

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Regular measurements of fluxes of charged particles in the Earth’s atmosphere conducted by theLebedev Physical Institute (LPI) made it possible to register since 1963 more than 500 cases of precipitationof energetic electrons in the northern polar latitudes. The obtained experimental data represent the world’sonly database on the precipitation of electrons registered directly in the Earth’s atmosphere. Primary precipitatingelectrons are absorbed in the upper layers of the atmosphere. However, the fluxes of secondary photonsgenerated by them can penetrate deep into the atmosphere, sometimes to heights of ~20 km, which areaccessible for balloon measurements by the Lebedev Physical Institute. This paper presents a new techniquefor reconstructing the energy spectrum of precipitating electrons developed on the basis of the Monte Carlosimulation of the processes of electron propagation in the atmosphere. The applicability of the technique tothe accumulated experimental data is shown, and new results are presented for individual events recorded inthe atmosphere.

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