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Wyświetlanie 1-15 z 78
Tytuł:
Еvaluation of health status of children attending primary schools with different organization of physical education lessons
Autorzy:
Kondratiuk, O.S.
Korshun, M.M.
Garkavyi, S.I.
Garkavyi, S.S.
Powiązania:
https://bibliotekanauki.pl/articles/874642.pdf
Data publikacji:
2018
Wydawca:
Narodowy Instytut Zdrowia Publicznego. Państwowy Zakład Higieny
Opis:
Background. The mandatory swimming lesson in primary schools, equipped with swimming pools, was introduced without studying of its health-saving effectiveness. Objective. The purpose of this study was to evaluate the health status of pupils studying in schools with different organization of physical education lessons. Materials and Methods. Cross-sectional study was organized in two schools with different organization of physical education lessons. The experimental group (E) consisted of 408 children of 1‑4 year of study (210 girls and 198 boys) who during one of the lessons of physical education were engaged in swimming in the school basin. Control group (C) consisted of 279 primary school children (210 girls and 156 boys) from a neighboring educational institution where all physical education lessons were organized in the gym. The health status was evaluated using classical method of complex assessment of the state of health with the subsequent assignment of each child to one of the health groups. Results. In result of evaluation of state of health there was established that among pupils from E group the proportion of boys with harmonious anthropometric parameters is higher (p<0.05), children from this group are stronger than C group (p<0.05). The prevalence of diseases of the musculoskeletal system and the eyes among pupils in E group was lower comparing to the C group (p<0.01). In the E group percentage of pupils assigned to health group I was significantly higher and lower for the II (children with some morpho-functional abnormalities) comparing to the C group. Conclusion. Organization of one mandatory swimming lesson per week in primary school has positive effect on health status of children.
Źródło:
Roczniki Państwowego Zakładu Higieny; 2018, 69, 2
0035-7715
Pojawia się w:
Roczniki Państwowego Zakładu Higieny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variability of the portion of functional PS2 reaction centres in the light of a fluorometric study
Autorzy:
Ficek, D.
Ostrowska, M.
Kuzio, M.
Pogosyan, S.I.
Powiązania:
https://bibliotekanauki.pl/articles/48365.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
marine phytoplankton
variability
quantum yield
chlorophyll a
optical depth
PS2 reaction
environmental factor
photosynthetic apparatus
sea
fluorometric method
light
photosynthesis
Opis:
The paper contains a preliminary analysis of the links between the portion fc of functional PS2 reaction centres in the photosynthetic apparatus of marine phytoplankton and environmental factors. The analysis is based inter alia on fluorometric measurements of fc (see Kolber & Falkowski 1993) in water sampled from different depths and trophic types of sea. From the statistical generalisations was derived an analytical form of the relationship between fc, and the optical depth and trophic type of sea (the trophicity index was taken to be the surface concentration of chlorophyll a). According to this relationship, fc rises as the trophicity of the sea does so. Moreover, there is a certain optimal optical depth for each type of water at which the number of functional PS2 reaction centres reaches a maximum. Above or below this depth the value of fc falls. At the present stage of investigations it seems reasonable to assume that this drop in the number of functional PS2 reaction centres close to the surface is due to the destructive effect of excessive irradiance. On the other hand, their reduced number at greater depths, below the fc maximum, can be attributed to the deficit of light and the consequent destruction of reaction centres.
Źródło:
Oceanologia; 2000, 42, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Using high level roadway to control gas emission in a longwall mining face – numerical simulation study
Autorzy:
Ma, Yongzhen
Cheng, Jianwei
Zhang, Rui
Wang, Zui
Ran, Dezhi
Sheng, Shuping
Zhang, Jufeng
Si, Junhong
Yu, Zhaoyang
Powiązania:
https://bibliotekanauki.pl/articles/2203351.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
symulacja numeryczna
wentylacja górnicza
kopalnia węgla
high level roadway
gob
numerical simulation
u+hLR ventilation method
Opis:
With the increase of coal mining depth, the gas content in coal seams could also become larger and larger, which could suddenly cause an inrush of gas into the longwall mining face. It is very dangerous for miners’ safety in the underground. The U-shaped ventilation pattern of longwall mining face that underground coal mines currently use is not enough to deliver sufficient air quantities to dilute gases in mining faces, which could result in the gas concentration over the required celling limit by government laws. Thus, the mine must stop production. In this paper, the high level roadway (HLR) is designed and the U + HLR new ventilation pattern is proposed to control gas emission in a longwall mining face. Using computational fluid dynamics simulation (CFD) software, the flow field and gas transportation in the mine gob are studied. The optimized ventilation parameters are summarized. It is found that the best vertical distance of the HLR is 35 m over the coal seam and the horizontal distance is 25 m from the air return roadway. It is recommended that the negative suction pressure design of the high level roadway should be ranged from 9000 Pa to 10000 Pa. Based on the study outcomes, the gas emission could be well controlled in mining faces and avoid any gas disaster accidents.
Źródło:
Archives of Mining Sciences; 2022, 67, 4; 715--728
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical and experimental analysis on the interaction properties between tracks and sediments considering sand content for unmanned underwater tracked bulldozer
Autorzy:
Li, Yong
He, Dingchang
Si, Qiaorui
Powiązania:
https://bibliotekanauki.pl/articles/2090708.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
unmanned underwater tracked bulldozer
underwater robot
river bed sediment
shear stress
pressure-sinkage
spychacz gąsienicowy bezzałogowy podwodny
robot podwodny
osad z koryta rzeki
naprężenie ścinające
spadek ciśnienia
Opis:
The unmanned underwater tracked bulldozer (UUTB) is an indispensable equipment for dredging and cleaning obstacles on the river bed in the flood season. The investigation on the interaction properties between the UUTB tracks and sediments provides foundation for the evaluation of operation performance when it works on the inland river bed. Based on the current worldwide research, the sediments mixed by sand, bentonite and water with sand content 0%, 10% and 20% were configured in this study to replace the real sediments on the inland river bed in China. The current pressure-sinkage model and shear stress-shear displacement model were discussed. Three different tracks were tested for the pressure-sinkage and the shear stress-shear displacement on the platform. The relationship between pressure and sinkage under sand content 0%, 10% and 20% are revealed based on the experimental results. The modulus of cohesive deformation and friction deformation of the sediments under said sand content are presented. The curves of shear stress and shear displacement are also obtained, which demonstrates the properties between the tracks and configured sediments under sand content 0%, 10% and 20%. The relationship between the tractive force and slip ratio with three different tracks under said sand content is also presented based on the quantitative analysis, which provides reference for the dynamics control and performance evaluation of UUTB on the inland river bed.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; e136036, 1--13
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical and experimental analysis on the interaction properties between tracks and sediments considering sand content for unmanned underwater tracked bulldozer
Autorzy:
Li, Yong
He, Dingchang
Si, Qiaorui
Powiązania:
https://bibliotekanauki.pl/articles/2173566.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
unmanned underwater tracked bulldozer
underwater robot
river bed sediment
shear stress
pressure-sinkage
spychacz gąsienicowy bezzałogowy podwodny
robot podwodny
osad z koryta rzeki
naprężenie ścinające
spadek ciśnienia
Opis:
The unmanned underwater tracked bulldozer (UUTB) is an indispensable equipment for dredging and cleaning obstacles on the river bed in the flood season. The investigation on the interaction properties between the UUTB tracks and sediments provides foundation for the evaluation of operation performance when it works on the inland river bed. Based on the current worldwide research, the sediments mixed by sand, bentonite and water with sand content 0%, 10% and 20% were configured in this study to replace the real sediments on the inland river bed in China. The current pressure-sinkage model and shear stress-shear displacement model were discussed. Three different tracks were tested for the pressure-sinkage and the shear stress-shear displacement on the platform. The relationship between pressure and sinkage under sand content 0%, 10% and 20% are revealed based on the experimental results. The modulus of cohesive deformation and friction deformation of the sediments under said sand content are presented. The curves of shear stress and shear displacement are also obtained, which demonstrates the properties between the tracks and configured sediments under sand content 0%, 10% and 20%. The relationship between the tractive force and slip ratio with three different tracks under said sand content is also presented based on the quantitative analysis, which provides reference for the dynamics control and performance evaluation of UUTB on the inland river bed.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; art. no. e136036
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The methodical maintenance of independent work in the suplementary professional educational system
Autorzy:
Nevdakh, S.I.
Powiązania:
https://bibliotekanauki.pl/articles/4808.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Humanistyczno-Przyrodniczy im. Jana Długosza w Częstochowie. Wydawnictwo Uczelniane
Opis:
This article reveals the methodic foundations of the organization of independent work in the supplementary professional educational system. The independent work is regarded as one of the compulsory parts of learning process. The author describes the types of independent work, conditions and stages of its organization, principles of its implementation, its methodic and service maintenance. The following types of independent work are presented: studying separate questions, themes, sections, not considered at the lessons and lectures; preparing for assistance to the teacher/lecturer; drawing up a plan; taking a test; writing a review, an annotation, a thesis, a synopsis, an abstract, a thematic report, an essay, a project, a course paper and a diploma paper and others.
В данной статье раскрываются методические основы организации самостоятельной работы в системе дополнительного профессионального образования. Самостоятельная работа является одним из обязательных видов учебной деятельности. Рассматриваются виды самостоятельной работы, условия и этапы ее организации, принципы реализации, методическое и сервисное обеспечение. Представлены виды заданий для самостоятельной работы слушателей: изучение отдельных вопросов, тем, разделов, не рассматриваемых на занятиях; подготовка к ассистированию преподавателю; составление плана; контрольная работа; составление рецензии; составление аннотации; составление тезисов; ведение конспекта; подготовка реферата; подготовка тематического сообщения; написание эссе; выполнение проекта, выполнение курсовой и дипломной работ и др.
Źródło:
Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Kultura Fizyczna; 2010, 09
1895-8680
Pojawia się w:
Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Kultura Fizyczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Impact of Coal Exploitation on Tidal Flat Changes, an Investigation Using Remote Sensing Data in Vietnam
Autorzy:
Pham, Thi Lan
Tong, Si Son
Le, Thi Thu Ha
Le, Thi Le
Hoang, Huu Duc
Powiązania:
https://bibliotekanauki.pl/articles/2020940.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
tidal flat
coal
remote Sensing
przypływy
węgiel
teledetekcja
Opis:
Tidal flat plays a crucial role in socio-economic development and ecological environment. Tidal flats in Ha Long-Cam Pha in Vietnam are impacted by human activities, especially coal mining activities. Using remote sensing data is able to detect, extract, and monitor the changes of tidal flats and exploited coal mine area with multi-temporal, in various scales, and for a large coverage. This study aims to investigate the impact of coal mining activities on the changes of tidal flats using remote sensing in Cam Pha, Ha Long, one of the biggest coal basins in Vietnam. Digital Elevation Models (DEMs) of tidal flats constructed by Landsat satellite images acquired in years 1989, 2001, and 2014 are compared to determine the volume changes. Besides, coal mining activities including coal production, waste rock dump area, and the expansion of open coal mine during the period 1989-2014 are investigated using correspondent Landsat images and the reports from the coal mine companies in the study area. Sediment samples in tidal flats are analyzed to determine the origin of the sediments. As the results, organic matter in the tidal flats is dominant with the concentration of 459 g/kg to 607 g/kg, which is evidence for the impact of coal exploitation on the coastal environment. In addition, the relationship between coal mine activities and tidal flat variation is well observed in this study.
Źródło:
Inżynieria Mineralna; 2021, 2; 521--532
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of energies on the impact breakage characteristic of magnetite ores
Autorzy:
Si, Liang
Cao, Yijun
Li, Guosheng
Powiązania:
https://bibliotekanauki.pl/articles/2200336.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fractal dimension
ore breakage characteristic
particle size distribution
mineral liberation
fracture morphology
Opis:
The energy applied during breakage is the key to enhancing the magnetite liberation degree and improving quality. The relationship between energy and liberation properties remains unclear due to various complicated factors affecting mineral liberation. Therefore, this work aims to study the effect of energy on the breakage characteristics of magnetite ores; the impact breakage test was conducted on magnetite particle groups at different energies using a drop weight impact tester; the statistical analysis was performed based on the fractal theory to research the particle size distribution; the fracture morphology and liberation properties of these ores were analyzed using scanning electron microscope and mineral liberation analyzer. Results show that the particle size distribution of magnetite after breakage conforms to the fractal law. The larger the energy, the greater the fractal dimension for this distribution, showing a linear relation between them, which implies that the fractal dimension can evaluate the breakage degree. The fracture morphology of magnetite ores indicates that as the energy increases, the intergranular fracture evolves into transgranular fracture, proving the influence of energy on fracture modes. It is found that the magnetite liberation degree first increases and then decreases with the rising of energy, indicating that the magnetite liberation can be improved at an appropriate amount of energy. The above conclusions provide a theoretical reference for optimizing energy and improving broken product quality.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 1; art. no. 159098
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Concentration of Defects at Grain Boundaries in Sintered Alumina Determined by Positron Annihilation Lifetime Spectroscopy
Autorzy:
Kansy, J.
Si Ahmed, A.
Liebault, J.
Moya, G.
Powiązania:
https://bibliotekanauki.pl/articles/2028969.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
77.84.Bw
61.72.Mm
Opis:
Sintered alumina samples of grain diameters spanning from 1.2 to 4.5μm have been investigated by positron annihilation lifetime spectroscopy. One series of samples was produced from material containing about 150 ppm impurities (mainly SiO$\text{}_{2}$). The second one was made from material having about 2700 ppm of various elements (SiO$\text{}_{2}$, MgO, CaO). Two models of positron trapping at grain boundaries are compared: The first one relates to the diffusion-limited regime; and the other one - to the transition-limited regime of trapping. As a result the relative change of surface concentration of defects at grain boundaries is determined. Additionally, the positron diffusion constant in bulk alumina at room temperature, D$\text{}_{+}$=0.36±10 cm$\text{}^{2}$/s, is estimated.
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 737-742
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Studying the thermo-gas-dynamic process in a muzzle brake compensator
Autorzy:
Nguyen, Dung Van
Bui, Viet Quy
Nguyen, Dung Thai
Uong, Quyen Si
Truong, Hieu Tu
Powiązania:
https://bibliotekanauki.pl/articles/27309887.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
thermo-gas-dynamic
muzzle device
muzzle brake compensator
automatic gun
dynamiczny termo-gaz
urządzenie wylotowe
kompensator hamulca wylotowego
pistolet automatyczny
Opis:
To reduce the recoil and improve the stability of small arms, a muzzle brake compensator is attached to the muzzle of the barrel. This device uses the kinetic energy of the powder gas escaping from the bore after the bullet is fired. In this paper, the authors present the determination of the thermo-gas-dynamic model of the operation of a muzzle brake compensator and an example of calculating this type of muzzle device for the AK assault rifle using 7.62x39 mm ammunition. The results of the calculation allowed for obtaining the parameters of the powder gas flow in the process of flowing out of the muzzle device, as well as the change in the momentum of the powder gas's impact on the muzzle device. The model proposed in the article provides the basis for a quantitative evaluation of the effectiveness of using the muzzle device in stabilizing infantry weapons when firing.
Źródło:
Archive of Mechanical Engineering; 2023, LXX, 2; 311--328
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on screening performance and parameters optimization of double relatively independent vibrating screen
Autorzy:
Li, Zhanfu
Hu, Yunxiao
Jia, Peiyu
Si, Qiming
Tong, Xin
Powiązania:
https://bibliotekanauki.pl/articles/2146862.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
RSM
non parallel
DEM-MBD co-simulation
relatively independent
Opis:
In view of the existing double-layer linear vibrating screen, the screen surface inclination angle is basically parallel design. This paper puts forward a double-layer non-parallel and relatively independent vibrating screen. Experimental prototype of double-layer relatively independent vibrating screen under variable parameters was manufactured to verify the feasibility of simulations. This paper applied the single-factor tests to establish relationships between screening parameters of double-layer non-parallel and relatively independent vibrating screen and screening performance. What’s more, the combination of screening parameters was optimized using the response surface method (RSM). The optimal combination after the round is as follow: vibration frequency 35 Hz, the angle of eccentric block 14.2°, the inclination of the upper screen 14.6° and the inclination of the lower screen 8.8°.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 6; 156--168
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on particle movement characteristics in sandblast cylinder based on PIV technology
Autorzy:
Hui, Zhiquan
Wu, Feng
Duan, Haojie
Yang, Bo
Lin, Jinmei
Wang, Lian
Huang, Si
Powiązania:
https://bibliotekanauki.pl/articles/778390.pdf
Data publikacji:
2020
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
PIV technology
Sandblast cylinder
Particles
Movement characteristics
Opis:
PIV technology was used to investigate the influence of the particles’ relevant parameters on the instantaneous movement characteristics in the sandblast cylinder under the circumstance of different particle sizes, different section heights and different stacking conditions. As the diameter increased, particles had a greater velocity and energy when approaching the wall, which would cause a serious abrasion. The influence of test selection factors on the particles’ radial velocity of particles was greater than that on axial velocity. The radial velocity and axial velocity on the surface of the cylindrical section were all reduced to a lower level when the particles approach the tank wall. When r > 0.3 R, the particle velocity maintained at a higher level, but then decreased slowly when r > 0.7 R. Therefore, the abrasion of the conical section of the sandblast cylinder when r > 0.3 R should be paid more attention to.
Źródło:
Polish Journal of Chemical Technology; 2020, 22, 3; 38-47
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stress evolution mechanism and thermo-mechanical reliability analysis of copper-filled TSV interposer
Autorzy:
Chen, Yuan
Su, Wei
Huang, Hong-Zhong
Lai, Ping
Lin, Xiao-ling
Chen, Si
Powiązania:
https://bibliotekanauki.pl/articles/1841909.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
through silicon vias
thermo-mechanical reliability
failure mechanism
finite element analysis
3D integrated packaging
thermal cycling experiment
Opis:
Through silicon via (TSV) has become one of the key emerging trends of three-dimensional (3D) packages, as it can realize vertically interconnect between stacked-dies. Due to large mismatch in thermal expansion coefficients (CTE) between the copper via and the silicon, significant mechanical stresses are induced at the interfaces when TSV structure is subjected to thermal stresses, which would greatly affect the reliability and electrical performance of TSV 3D device. In this paper, the relationship between the state of stresses and failure of TSV had been explored by combining finite element model simulation (FEM) and failure physical analysis. The position of the maximum stress of the TSV structure was obtained by FEM analysis. The relationship of stress and displacement change with temperature was also studied. And a thermal cycling experiment was conducted to validate the simulation results. Physical failure analysis after thermal cycling experiment was used to verify the degradation mechanism predicted by thermo-mechanical simulation.
Źródło:
Eksploatacja i Niezawodność; 2020, 22, 4; 705-714
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatio-temporal dynamics of vegetation cover in North-West Algeria using remote sensing data
Autorzy:
Tayeb, Tayeb Si
Kheloufi, Benabdeli
Powiązania:
https://bibliotekanauki.pl/articles/92530.pdf
Data publikacji:
2019
Wydawca:
Oddział Kartograficzny Polskiego Towarzystwa Geograficznego
Tematy:
land cover
spatio-temporal dynamics
remote sensing
NDVI
Oranie
Opis:
Land cover change is the result of complex interactions between social and environmental systems which change over time. While climatic and biophysics phenomena were for a long time the principal factor of land transformations, human activities are today the origin of the major part of land transformation which affects natural ecosystems. Quantification of natural and anthropogenic impacts on vegetation cover is often hampered by logistical issues, including (1) the difficulty of systematically monitoring the effects over large areas and (2) the lack of comparison sites needed to evaluate the effect of the factors. The effective procedure for measuring the degree of environmental change due to natural factors and human activities is the multitemporal study of vegetation cover. For this purpose, the aim of this work is the analysis of the evolution of land cover using remote sensing techniques, in order to better understand the respective role of natural and anthropogenic factors controlling this evolution. A spatio-temporal land cover dynamics study on a regional scale in Oranie, using Landsat data for two periods (1984–2000) and (2000–2011) was conducted. The images of the vegetation index were classified into three classes based on Normalized Difference Vegetation Index (NDVI) values and analysed using image difference approach. The result shows that the vegetation cover was changed. An intensive regression of the woody vegetation and forest land resulted in -22.5% of the area being lost between 1984 and 2000, 1,271 km2 was converted into scrub formations and 306 km2 into bare soil. On the other hand, this class increased by around 45% between 2000 and 2011, these evolutions resulting from the development of scrub groups with an area of 1,875.7 km2.
Źródło:
Polish Cartographical Review; 2019, 51, 3; 117-127
2450-6974
Pojawia się w:
Polish Cartographical Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spark Plasma Sintering of Mn-Zn Ferrite Powders by High Energy Ball Milling
Autorzy:
Suh, Jun Young
Song, Yo-Seung
Chang, Si Young
Powiązania:
https://bibliotekanauki.pl/articles/351276.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high energy ball milling
nano-sized particles
SPS
conventional sintering
density
Opis:
The Mn-Zn ferrite powders prepared by high energy ball milling were heat-treated, subsequently compacted and sintered by spark plasma sintering (SPS). Based on the observation of microstructure, the characteristics of samples after SPS were investigated and compared with ones after conventional sintering. The size of initial powders was approximately 650 nm and decreased to 230 nm after milling at 300 rpm for 3 h. After heat treatment at 973 K for 1 h, the milled powders became larger to approximately 550 nm in size again and the peaks of Mn2 O3 disappeared in XRD patterns. In the samples after SPS, the Fe2 O3 and MnZnFe2 O4 phases decomposed at the higher temperatures than 1173 K and 1373 K, respectively, while only MnZnFe2 O4 phase was detected in the samples conventionally sintered at 1273~1673 K. As the sintering temperature increased, the relative density after SPS increased more quickly than that after conventional sintering. In particular, it reached approximately 99% after SPS at 1473 K.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 565-569
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 78

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