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Wyświetlanie 1-15 z 54
Tytuł:
Effect of Trace Elements (Co, Cr) on the Microstructure and Physical Properties of Al-Si-Cu-Mg-Fe Extruded Alloy
Autorzy:
Ahn, S. S.
Sharief, P.
Lee, C. H.
Son, H. T.
Kim, Y. H.
Kim, Y. C.
Hong, S.
Hong, S. J.
Powiązania:
https://bibliotekanauki.pl/articles/352787.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-Si alloy
microstructure
extrusion
coefficient of thermal expansion
trace elements
Opis:
Trace elements Co, Cr were added to investigate their influence on the microstructure and physical properties of Al-Si extruded alloy. The Co, Cr elements were randomly distributed in the matrix, forms intermetallic phase and their existence wereconfirmed by XRD, EDS and SEM analysis. With addition of trace elements, the microstructure was modified, Si particle size was reduced and the growth rate of β-(Al5 FeSi) phase limited. Compared to parent alloy, hardness and tensile strength were enhanced while the linear coefficient of thermal expansion (CTE) was significantly reduced by 42.4% and 16.05% with Co and Cr addition respectively. It is considered that the low CTE occurs with addition of Co was due to the formation of intermetallic compound having low coefficient of thermal expansion. The results suggested that Co acts as an effective element in improving the mechanical properties of Al-Si alloy.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 3; 857-862
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carbon Co-Deposition During Gas Reduction of Water-Atomized Fe-Cr-Mo Powder
Autorzy:
Ali, B.
Choi, S. H.
Seo, S. J.
Maeng, D. Y.
Lee, C. G.
Kim, T. S.
Park, K. T.
Powiązania:
https://bibliotekanauki.pl/articles/352709.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
water atomization
Fe-based powder
oxide reduction
powder metallurgy
sinter-hardening alloys
Opis:
The water atomization of iron powder with a composition of Fe-3Cr-0.5Mo (wt.%) at 1600°C and 150 bar creates an oxide layer, which in this study was reduced using a mixture of methane (CH4) and argon (Ar) gas. The lowest oxygen content was achieved with a 100 cc/min flow rate of CH4, but this also resulted in a co-deposition of carbon due to the cracking of CH4. This carbon can be used directly to create high-quality, sinter hardenable steel, thereby eliminating the need for an additional mixing step prior to sintering. An exponential relationship was found to exist between the CH4 gas flow rate and carbon content of the powder, meaning that its composition can be easily controlled to suit a variety of different applications.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1119-1124
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Fe Content on the Microstructure and Mechanical Properties of Ti-Al-Mo-V-Cr-Fe Alloys
Autorzy:
Bae, K.-C.
Oak, J.-J.
Kim, Y. H.
Park, Y. H.
Powiązania:
https://bibliotekanauki.pl/articles/351896.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Ti alloy
near-β titanium alloy
aircraft applications
structural material
landing gear
Opis:
To investigate the effect of Fe content on the correlation between the microstructure and mechanical properties in near-b titanium alloys, the Ti-5Al-5Mo-5V-1Cr-xFe alloy system has been characterized in this study. As the Fe content increased, the number of nucleation sites and the volume fraction of the α phase decreased. We observed a significant difference in the shape and size of the α phase in the matrix before and after Fe addition. In addition, these morphological deformations were accompanied by a change in the shape of the α phase, which became increasingly discontinuous, and changed into globular-type α phase in the matrix. These phenomena affected the microstructure and mechanical properties of Ti alloys. Specimen #2 exhibited a high ultimate tensile strength (1071 MPa), which decreased with further addition of Fe.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1105-1108
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A queueing system with heterogeneous impatient customers and consumable additional items
Autorzy:
Baek, J.
Dudina, O.
Kim, C.
Powiązania:
https://bibliotekanauki.pl/articles/907646.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
marked Markovian arrival process
consumable additional items
phase type distribution
impatient customer
Markowski proces zgłoszeń
system kolejkowy
rozkład fazowy
klient niecierpliwy
Opis:
A single-server queueing system with a marked Markovian arrival process of heterogeneous customers is considered. Type-1 customers have limited preemptive priority over type-2 customers. There is an infinite buffer for type-2 customers and no buffer for type-1 customers. There is also a finite buffer (stock) for consumable additional items (semi-products, half-stocks, etc.) which arrive according to the Markovian arrival process. Service of a customer requires a fixed number of consumable additional items depending on the type of the customer. The service time has a phase-type distribution depending on the type of the customer. Customers in the buffer are impatient and may leave the system without service after an exponentially distributed amount of waiting time. Aiming to minimize the loss probability of type-1 customers and maximize throughput of the system, a threshold strategy of admission to service of type-2 customers is offered. Service of type-2 customer can start only if the server is idle and the number of consumable additional items in the stock exceeds the fixed threshold. Stationary distributions of the system states and the waiting time are computed. In the numerical example, we show some interesting effects and illustrate a possibility of application of the presented results for solution of optimization problems.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2017, 27, 2; 367-384
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A study on the development of a new grinding processes for high-lead ball screw nuts
Autorzy:
Choi, Ch.
Ha, Y.
Kim, H.
Lee, C.
Powiązania:
https://bibliotekanauki.pl/articles/99599.pdf
Data publikacji:
2010
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
high-lead ball screw nuts
new grinding process
surface roughness
Opis:
This paper proposes a method that machines the race of high-lead ball screw nuts, which is difficult to machine using the existing geometrical machining method, without any interferences and changes in its load rating in order to perform the high-speed in ball screws. This study calculates the inclination angle of the axis of the grinding stone for avoiding the contact of the axis to the inner diamete of the nut and determines the shape of the grinding stone through changing the inclination angle and dressing curvature determined in a dressing device Then, the grinding condition will be determined by measuring the shape meter of the screw race for solving the problem. Also, the surface roughness of the grinded surface was measured using a surface roughness tester, and check with applying a grinding process of product not being high-lead ball screw.
Źródło:
Journal of Machine Engineering; 2010, 10, 1; 50-57
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An analysis on the thermal characteristics according to the viscosity of bearing lubricant and the cooling condition for the high speed motor spindle
Autorzy:
Choi, D. B.
Lee, J. J.
Kim, S. T.
Kwon, H. D.
Kim, C. Y.
Powiązania:
https://bibliotekanauki.pl/articles/1429194.pdf
Data publikacji:
2008
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
high speed motor spindle
thermal displacement cooling condition
lubricant viscosity
Opis:
Thermal displacement of the high speed machine tools has a large influence on machining accuracy. The high speed motor spindle with many heat sources is widely used for the high speed machine tools recently. The important problem in this spindle is to reduce and minimize the thermal effects by motor and bearings. This paper presents the analysis on thermal characteristics for high speed motor spindle system with oil-air lubricated angular contact ceramic ball bearings and built-in motor. An analysis on the thermal characteristics of spindle is performed according to the cooling conditions and the viscosity of bearing lubricants by using finite element method. This results can be applied to the design and manufacturing for the high speed motor spindle.
Źródło:
Journal of Machine Engineering; 2008, 8, 4; 88-98
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of Carbon Nanotube Based Reflection Type X-ray Source
Autorzy:
Choi, H.
Kim, J.
Lee, C.
Powiązania:
https://bibliotekanauki.pl/articles/1807922.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
75.47.Gk
73.50.Fq
Opis:
X-ray imaging technology is a useful and leading medical diagnostic tool for health care professionals to diagnose disease in human body. Carbon nanotube based X-ray source, which we have developed in this study, could be also useful and supply integrated diagnostic X-ray imaging tool in diagnosis. Conventionally, thermionic type of tungsten filament X-ray tube is widely employed in the field of biomedical and industrial application fields. However, intrinsic problems, such as poor emission efficiency, low imaging resolution, and high electrical energy consumption etc., may cause the limitation of using the X-ray tube. To fulfill the current market requirement, specifically for medical diagnostic field, we have developed rather a portable and compact carbon nanotube based X-ray device in which microfocus high imaging resolution can be feasible.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1078-1080
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Extraction Process Of Rare Earth Elements From NdFeB Powders Via Alkaline Treatment
Nowy sposób ekstrakcji pierwiastków ziem rzadkich z proszków NdFeB w roztworach alkalicznych
Autorzy:
Chung, K. W.
Kim, C.-J.
Yoon, H.-S.
Powiązania:
https://bibliotekanauki.pl/articles/355324.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
recycling
NdFeB magnet
alkaline treatment
leaching
selective leaching efficiency
recykling
magnes neodymowy
obróbka alkaliczna
ługowanie
wydajność
Opis:
The alkaline treatment of NdFeB powders in NaOH solution at various equivalent amounts of NaOH at 100°C was performed. The resultant powders were then leached in 0.5M H2SO4 solution at 25°C for 2 minutes. At 5 equivalents of NaOH, neodymium in NdFeB powders was partially transformed to neodymium hydroxide. The transformation of neodymium to neodymium hydroxide actually occurred at 10 equivalents of NaOH and was facilitated by increasing the equivalent of NaOH from 10 to 30. In addition, iron was partially transformed to magnetite during the alkaline treatment, which was also promoted at a higher equivalent of NaOH. The leaching yield of neodymium from alkaline-treated powders was increased with an increasing equivalent of NaOH up to 10; however, it slightly decreased with the equivalent NaOH of over 10. The leaching yield of iron was inversely proportional to that of rare earth elements. NdFeB powders treated at 10 equivalents of NaOH showed a maximum leaching yield of neodymium and dysprosium of 91.6% and 94.6%, respectively, and the lowest leaching yield of iron of 24.2%, resulting in the highest selective leaching efficiency of 69.4%.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1301-1305
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Purity Tungsten Spherical Particle Preparation From WC-Co Spent Hard Scrap
Wytwarzanie wysokiej czystości sferycznych cząstek wolframu z twardego złomu WC-Co
Autorzy:
Han, C.
Na, H.
Choi, H.
Kim, Y.
Powiązania:
https://bibliotekanauki.pl/articles/351951.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
WC-Co
spent hard scrap
hydrometallurgy
RF thermal plasma
twardy złom
hydrometalurgia
plazma termiczna
Opis:
Tungsten carbide-cobalt hard metal scrap was recycled to obtain high purity spherical tungsten powder by a combined hydrometallurgy and physical metallurgy pathway. Selective leaching of tungsten element from hard metal scrap occurs at solid / liquid interface and therefore enlargement of effective surface area is advantageous. Linear oxidation behavior of Tungsten carbide-cobalt and the oxidized scrap is friable to be pulverized by milling process. In this regard, isothermally oxidized Tungsten carbide-cobalt hard metal scrap was mechanically broken into particles and then tungsten trioxide particle was recovered by hydrometallurgical method. Recovered tungsten trioxide was reduced to tungsten particle in a hydrogen environment. After that, tungsten particle was melted and solidified to make a spherical one by RF (Ratio Frequency) thermal plasma process. Well spherical tungsten micro-particle was successfully obtained from spent scrap. In addition to the morphological change, thermal plasma process showed an advantage for the purification of feedstock particle.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1507-1509
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recovery Of Valuable Metals In Tin-Based Anodic Slimes By Carbothermic Reaction
Odzysk cennych metali ze szlamów anodowych na bazie Sn metodą reakcji karbotermicznej
Autorzy:
Han, C.
Kim, Y.-M.
Son, S. H.
Choi, H.
Kim, T. B.
Kim, Y. H.
Powiązania:
https://bibliotekanauki.pl/articles/352796.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
tin
anodic slime
carbothermic reduction
carbon
recovery
cyna
szlam anodowy
reakcja karbotermiczna
węgiel
odzysk metali
Opis:
This study investigated the recovery of anodic slimes by carbothermic reaction in the temperature range of 973~1,273K and amount of carbon as a function of time. Tin anodic slime samples were collected from the bottom of the electrolytic cells during the electro-refining of tin. The anodic slimes are consisted of high concentrated tin, silver, copper and lead oxides. The kinetics of reduction were determined by means of the weight-loss measurement technique. In order to understand in detail of carbothermic reaction, thermodynamic calculation was carried out and compared with experiments. From thermodynamic calculation and experiment, it was confirmed that Sn-based anodic slime could be reduced by controlling temperature and amount of carbon. However, any tendency between the reduction temperature and carbon content for the reduction reaction was not observed.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1213-1216
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on Effects of Mold Temperature on the Injection Molded Article
Autorzy:
Han, J.-H.
Kim, Y.-C.
Powiązania:
https://bibliotekanauki.pl/articles/351919.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
injection molding
mold temperature
cooling temperature
molded article
Opis:
This is a study of the effects of temperature of injection mold on the injection molded article. By supplying water of the proper temperature in the cooling line of mold in the cooling process, the mold was the appropriate temperature, and the deformation of the injection molded article was examined according to the mold temperature. In this study, we conducted simulation analysis and experiments, and the results were analyzed. The minimum deformation of the injection molded article model obtained by supplying 50°C water in the cooling line is 0.003 mm, and the maximum deformation was 0.813 mm. Injection molded article models obtained by supplying 20°C water were found to be a minimum of 0.002 mm, with deformation of up to 0.761 mm. When comparing both conditions, the error rate of injection molded article obtained by supplying 20°C water in the mold cooling line was lower by about 0.18%.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1271-1274
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of an Incentive-Based Obesity Management Program in a Workplace
Autorzy:
Hwang, G.
Yoon, C.
Jung, H.
Kim, Y.
Powiązania:
https://bibliotekanauki.pl/articles/90493.pdf
Data publikacji:
2011
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
obesity
workplace
incentive
BMI
Opis:
This study is to analyze the effectiveness of an incentive-based obesity management program (the Midas Project aimed to improve good health habits) at an electronics company in 2005. A total of 95 company participants with a high body mass index (BMI) were recruited for a health promotion program for 3 months that awarded gold medals as an incentive for body fat loss. BMI decreased from 28.8 to 27.8 kg/m² (p = .000), body weight decreased from 87.2 to 83.5 kg (p = .000), and body fat weight decreased from 25.4 to 23.3 kg (p = .000). Systolic and diastolic blood pressure decreased from 130.5 to 125.1 mmHg (p = .002), from 86.4 to 81.7 mmHg (p = .009). The percentage of participants exercising more than 3 times per week increased from 27.3 to 52.3% (p = .000). The percentage who avoided overeating at parties and midnight eating increased from 65.9 to 72.7% (p = .767) and 70.5 to 84.1% (p = .172), respectively. This incentive-based obesity management program was effective in improving not only BMI but also health status.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2011, 17, 2; 147-154
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double Step Sintering Behavior Of 316L Nanoparticle Dispersed Micro-Sphere Powder
Dwuetapowe spiekanie mikrosferycznych nanocząstek proszku 316L
Autorzy:
Jeon, B.
Sohn, S. H.
Lee, W.
Han, C.
Kim, Y. D.
Choi, H.
Powiązania:
https://bibliotekanauki.pl/articles/355221.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
316L stainless steel
nanoparticle dispersed micro-sphere
pulse wire explosion
sintering
stal nierdzewna 316L
spiekanie dwuetapowe
mikrosferyczne nanocząstki
Opis:
316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present study, a nanoparticle dispersed micro-sphere powder is synthesized by pulse wire explosion of 316L stainless steel wire in order to facilitate compaction ability and sintering ability. Nanoparticles which are deposited on the surface of micro-powder are advantageous for a rigid die compaction while spherical micro-powder is not to be compacted. Additionally, double step sintering behavior is observed for the powder in the dilatometry of cylindrical compact body. Earlier shrinkage peak comes from the sintering of nanoparticle and later one results from the micro-powder sintering. Microstructure as well as phase composition of the sintered body is investigated.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1155-1158
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Modification of Self-Consolidated Microporous Ti Implant Compacts Fabricated by Electro-Discharge-Sintering in Air
Autorzy:
Jo, Y. J.
Yoon, Y. H.
Kim, Y. H.
Chang, S. Y.
Kim, J. Y.
Lee, Y. K.
Van Tyne, C. J.
Lee, W. H.
Powiązania:
https://bibliotekanauki.pl/articles/356790.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
titanium
implant
porous
sintering
X-ray photoelectron spectroscopy (XPS)
Opis:
A single pulse of 0.75-2.0 kJ/0.7g of atomized spherical Ti powders from 300 mF capacitor was applied to produce a microporous Ti implant compact by electro-discharge-sintering (EDS). A solid core in the middle of the compact surrounded by a microporous layer was found. X-ray photoelectron spectroscopy was employed to study the surface characteristics of the EDS Ti compact and it revealed that Ti, C and O were the main constituents on the surface with a smaller amount of N. The surface was lightly oxidized and was primarily in the form of TiO2 resulting from the air oxidation during EDS processing. The lightly oxidized surface of the EDS compact also exhibited Ti nitrides such as TiN and TiON, which revealed that the reaction between air constituents and the Ti powders even in times as short as 128 msec.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1287-1291
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bringing Kano’s perspective to AHP: the 2D-AHP decision model
Autorzy:
Jung, U.
Yim, S.
Lim, S.
Kim, C.
Powiązania:
https://bibliotekanauki.pl/articles/407247.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
analytic hierarchy process (AHP)
Kano model
hybrid model
multicriteria decision making
two dimension perspective
Opis:
AHP and the Kano model are such prevalent TQM tools that it may be surprising that a true hybrid decision-making model has so far eluded researchers. The quest for a hybrid approach is complicated by the differing output perspective of each model, namely discrete ranking (AHP) versus a multi-dimensional picture (Kano). This paper presents a hybrid model of AHP and Kano model, so called two-dimension AHP (2D-AHP). This paper first compares the two approaches and justifies a hybrid model based on a simple conceit drawn from the Kano perspective: given a decision hierarchy, child and parent elements can exhibit multi-dimension relationships under different circumstances. Based on this premise, the authors construct a hybrid two-dimension AHP model whereby a functionaldysfunctional question-pair technique is incorporated into a traditional AHP framework. Using the proposed hybrid model, this paper provides a practical test case of its implementation. The 2D-AHP approach revealed important evaluation variances obscured through AHP, while a survey study confirmed that the 2D-AHP approach is both feasible and preferred in some respects by respondents. Although there have been rich research efforts to combine AHP and Kano model, most of them is simply about a series of individual usage of each methodology. On the other hand, the type of hybridization between AHP and Kano model in this paper is quite unique in terms of the two dimensional perspective. The model provides a general approach with application possibilities far beyond the scope of the test case and its problem structure, and so calls for application and validation in new cases.
Źródło:
Management and Production Engineering Review; 2016, 7, 4; 16-26
2080-8208
2082-1344
Pojawia się w:
Management and Production Engineering Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 54

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