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Статті в журналах з теми "Gas shrinkage porosity"
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Dybowski, Bartłomiej, Łukasz Poloczek, and Andrzej Kiełbus. "The Porosity Description in Hypoeutectic Al-Si Alloys." Key Engineering Materials 682 (February 2016): 83–90. http://dx.doi.org/10.4028/www.scientific.net/kem.682.83.
Повний текст джерелаАнотація:
Al-Si alloys are the most important group among aluminum casting alloys. They are widely used in automotive and aerospace industries. Chemical modification of the Al-Si alloys leads to formation of fine, fibrous Al-Si eutectic mixture ensuring high mechanical properties. The modification is however known to increase the alloy porosity, which may, in turn, result in decrease of its properties. The following paper presents results of the research on quantitative description of the Al-Si cast alloys porosity and influence of Na modification on the porosity of AlSi9Mg alloy. Porosity in the hypoeutectic Al-Si alloys occurs in four types: shrinkage cavities, shrinkage porosity, isolated gas pores and gas pores surrounded by shrinkage porosity. Na modification leads to increase of shrinkage pores volume fraction.
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Kim, Sung Bin, Young Hoon Yim, Joong Mook Yoon, and Doru Michael Ştefănescu. "Prediction of Shrinkage Defects in Iron Castings Using a Microporosity Model." Materials Science Forum 925 (June 2018): 411–18. http://dx.doi.org/10.4028/www.scientific.net/msf.925.411.
Повний текст джерелаАнотація:
A numerical model for prediction of shrinkage defects in iron castings has been developed. The model is based on gas pores evolution during solidification. It describes the evolution of gas concentration using mass conservation, and the change in melt pressure due to solidification contraction using Darcy’s equation, with mixture continuity assumption in the liquid and the mushy zone. Gas pores nucleation has been calculated using the partial pressure of gas obtained from Sievert’s law. The growth of porosity has been estimated using an equation based upon the total melt pressure on the pore, concentration and temperature of the gas. The porosity model was calibrated against literature data for microporosity, and then applied to the prediction of shrinkage defects in a ductile iron casting. Comparison between the model predictions and experimental measurements indicated that the porosity model can be applied not only to the prediction of micro-shrinkage but also to that of macro-shrinkage. Existing shrinkage prediction models based upon thermal models, such as Niyama criterion and the modulus of retained melt in mushy regions cannot predict correctly both micro- and macro-shrinkage.
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Roskosz, Stanisław. "Quantitative Characterization of Shrinkage and Gas Pores in Turbine Blades Made of MAR M247 and IN 713C Superalloys." Solid State Phenomena 197 (February 2013): 64–69. http://dx.doi.org/10.4028/www.scientific.net/ssp.197.64.
Повний текст джерелаАнотація:
The subject matter of the paper is the quantitative evaluation of gaseous and shrinkage porosity in construction elements of a low-pressure aircraft engine turbine using quantitative metallography methods. The research material comprised blades and blade segments with a polycrystalline structure made of IN 713C and MAR M247 superalloys. One of the major problems that occur in the precision castings is their porosity: gaseous, which is the result of emission of dissolved gases from the superalloy during solidification, and shrinkage, being the result of shrinkage of the superalloy and of insufficient feeding of the interdendritic space. The developed practical procedure of selective measurement of gaseous and shrinkage porosity enabling the examination of precision castings made of high-temperature creep resisting nickel superalloys is presented.
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Thanabumrungkul, S., W. Jumpol, Rungsinee Canyook, N. Meemongkol, and Jessada Wannasin. "Characterization of Microstructure and Shrinkage Porosity of a Semi-Solid Metal Slurry in Gravity Die Casting." Solid State Phenomena 285 (January 2019): 161–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.285.161.
Повний текст джерелаАнотація:
Current aluminum automotive parts such as wheels, engine and transmission components are produced by tilted gravity die casting for control gas porosity. But, there are still problems resulting in inefficient production: shrinkage porosity, microstructure size and uniformity. Shrinkage porosity is one of the major issues which affects mechanical properties such as strength and elongation in tilted pour permanent mold. Recent work using slurry casting technique has shown potential in gravity sand casting. Results show that the casting parts have complete filling at low solid fractions and the casting yield is also higher than conventional gravity sand casting. This paper extends important work for potential industrial applications in gravity die casting: microstructure size, uniformity, solid fraction control for micro shrinkage level.
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Rashid, Abira. "Optimization of Shrinkage Porosity in Grinding Media Balls by Casting Design Modification and Simulation Technique." International Journal for Research in Applied Science and Engineering Technology 9, no. VIII (August 15, 2021): 344–53. http://dx.doi.org/10.22214/ijraset.2021.37352.
Повний текст джерелаАнотація:
Shrinkage porosity or cavity are associated with the solidification of the metal either due to gas/air entrapment or when the shrinkage occurring during solidification is not entirely compensated by the riser. Shrinkage cavities occurring in the casting reduces its strength which leads to unfulfillment of the desired serviceability. In this paper, casting design has been modified using the DISA manual to achieve directional solidification which directly relates to improvement of casting quality. The running of metal from pouring basin into casting along with solidification has been analysed through PROCAST which is a casting simulation software based on Finite Element Method and CAFE (Cellular Automata Finite Element) Model. The feeding system of the casting has been modified in terms of shape and volume to minimize air aspiration effect and promote directional solidification. The model used is of grinding media balls casting of high chromium cast iron. The feeding pattern, feeding velocity and solidification with respect to pouring temperature, pouring rate, ambient temperature and film coefficient has been analysed. The final optimum range of all parameters with corresponding minimum shrinkage porosity in casting was obtained. Main aim was to minimize shrinkage porosity in the main casting, ignoring gating and feeding system. The actual minimization of shrinkage porosity comes out around 56 %.
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Wannasin, Jessada, Marc Fuchs, Ji Yong Lee, Cheol Ung Lee, T. V. L. Narasimha Rao, and Merton C. Flemings. "GISS Technology: Principle and Applications in Die Casting." Solid State Phenomena 285 (January 2019): 470–75. http://dx.doi.org/10.4028/www.scientific.net/ssp.285.470.
Повний текст джерелаАнотація:
In the past, there have been a lot of effort to solve gas and shrinkage porosity defects in die casting. The common solutions are vacuum technology, jet cooling technology, and application of squeeze pins. However, these solutions often increase the die casting production costs. A new solution that has recently been introduced worldwide is GISS Technology. This technology applies the superheated slurry casting process. Gas and shrinkage porosity defects can be reduced. Furthermore, the production costs are lowered due to die life extension, cycle time reduction, melting energy reduction, and lubrication usage reduction. This paper describes the principle of GISS Technology, and selected applications and case studies are also be presented.
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Ignaszak, Z., and J. Hajkowski. "Contribution to the Identification of Porosity Type in AlSiCu High-Pressure-Die-Castings by Experimental and Virtual Way." Archives of Foundry Engineering 15, no. 1 (March 1, 2015): 143–51. http://dx.doi.org/10.1515/afe-2015-0026.
Повний текст джерелаАнотація:
Abstract The paper concerns the problem of discontinuity in high pressure die castings (HPDC). The compactness of their structure is not perfect, as it is sometimes believed. The discontinuities present in these castings are the porosity as follow: shrinkage and gas (hydrogen and gas-air occlusions) origin. The mixed gas and shrinkage nature of porosity makes it difficult to identify and indicate the dominant source. The selected parameters of metallurgical quality of AlSi9Cu3 alloy before and after refining and the gravity castings samples (as DI - density index method), were tested and evaluated. This alloy was served to cast the test casting by HPDC method. The penetrating testing (PT) and metallographic study of both kinds of castings were realized. The application of the NF&S simulation system allowed virtually to indicate the porosity zones at risk of a particular type in gravity and high-pressure-die-castings. The comparing of these results with the experiment allowed to conclude about NF&S models validation. The validity of hypotheses concerning the mechanisms of formation and development of porosity in HPDC casting were also analyzed.
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Bhagavath, Shishira, Zhixuan Gong, Tim Wigger, Saurabh Shah, Bita Ghaffari, Mei Li, Shashidhara Marathe, Shyamprasad Karagadde, and Peter D. Lee. "Mechanisms of gas and shrinkage porosity formation in solidifying shear bands." Journal of Materials Processing Technology 299 (January 2022): 117338. http://dx.doi.org/10.1016/j.jmatprotec.2021.117338.
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Zhou, Fengde, Guangqing Yao, Zhonghua Tang, and Oyinkepreye D. Orodu. "Influence and Sensitivity Study of Matrix Shrinkage and Swelling on Enhanced Coalbed Methane Production and CO2 Sequestration with Mixed Gas Injection." Energy Exploration & Exploitation 29, no. 6 (December 2011): 759–75. http://dx.doi.org/10.1260/0144-5987.29.6.759.
Повний текст джерелаАнотація:
Matrix compressibility, shrinkage and swelling can cause profound changes in porosity and permeability of coalbed during gas sorption and desorption. These factors affect the distribution of pressure, methane production and CO2 sequestration. This paper compares the effects of cleat compression and matrix shrinkage and swelling models with the injection of different compositional gas mixtures (CO2 and N2). It shows that well performance, pressure distribution and properties of the seam are strongly affected by matrix shrinkage and swelling. Matrix shrinkage and swelling also affects net present value of the enhanced coalbed methane recovery scheme. In order to select the best enhanced coalbed methane recovery schemes, economic evaluation and sensitivity studies are necessary.
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Rattanadakul, Sureebhorn, Jessada Wannasin, Somjai Janudom, Thawatchai Plookphol, and Sirikul Wisutmethangoon. "Effects of Solid Fractions in a Slurry Casting Process on Shrinkage and Microstructure of 7075 Aluminum Alloy." Advanced Materials Research 968 (June 2014): 125–28. http://dx.doi.org/10.4028/www.scientific.net/amr.968.125.
Повний текст джерелаАнотація:
Effects of Gas Induce Semi Solid (GISS) on shrinkage porosity of 7075 aluminum alloy were investigated. Initial solid fractions were controlled by rheocasting time at 5, 10 and 15 seconds and 4 and 6 bar of gas pressure. The results showed that the initial solid fractions were increased by increasing rheocasting time and gas pressure. As for the shrinkage, values of the GISS process samples were lower than those of the conventional process samples. In addition, the shrinkage areas of semi solid samples were decreased by increasing the initial solid fractions. The microstructure of semi solid samples was shown to be uniform globular grains along the samples.
Дисертації з теми "Gas shrinkage porosity"
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O'Brien, Evan Daniel. "Welding with Low Alloy Steel Filler Metal of X65 Pipes Internally Clad with Alloy 625: Application in Pre-Salt Oil Extraction." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1469018389.
Повний текст джерела
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Абдулкеримов, Илимдар Диляверович. "Технологическое обеспечение качества резьбовых соединений в глухих отверстиях деталей из алюминиевых сплавов деформирующим инструментом". Thesis, НТУ "ХПІ", 2015. http://repository.kpi.kharkov.ua/handle/KhPI-Press/20297.
Повний текст джерелаАнотація:
Диссертация на соискание учёной степени кандидата технических наук по специальности 05.02.08 – технология машиностроения. Национальный технический университет "Харьковский политехнический институт", Харьков, 2016.
Диссертация посвящена решению научно-технической задачи технологического обеспечения герметичности резьбовых соединений деталей из алюминиевых сплавов с газо-усадочной пористостью деформирующим инструментом. В работе проведен анализ существующих систем обработки глухих отверстий в алюминиевых сплавах из газо-усадочных материалов, выявлены основные факторы, определяющие качество и производительность процесса обработки отверстий. Показано, что для таких процессов как обеспечение необходимых эксплуатационных характеристик соединений нужно управлять параметрами состояния поверхностного слоя в процессе их изготовления, а также уметь рассчитывать их на стадии проектирования технологического процесса. Показано исследование технологических свойств алюминиевого сплава АК12М2, полученного литьем под давлением, а именно проведено моделирование ППД литейного алюминиевого сплава АК12М2, а также сравнение свойств поверхности до и после ППД и влияние угла деформации с учетом количества циклов ППД на качество поверхности. Результаты проведенных исследований позволили дать практические рекомендации по внедрению результатов работы на ОАО "Пневматика" (г. Симферополь), а именно показана обработка на примере детали корпус крана ПКР25 и получены герметичные разъемных соединения в деталях из алюминиевых сплавов с газо-усадочной пористостью. Проведено сравнение качества резьбовых соединений, получаемых по базовому и новому варианту обработки и оценка экономической эффективности. Это позволило снизить технологическую себестоимость и получить экономический эффект в размере 18207 грн., за счёт снижения трудоёмкости обработки, затрат на инструмент и технологические жидкости.The thesis for the degree of candidate of technical sciences, specialty 05.02.08 - technology of mechanical engineering. National Technical University "Kharkiv Polytechnic Institute", Kharkov, 2016. The dissertation is devoted to the processing to ensure the tightness of threaded connections of details from aluminum alloys deformed gas shrinkage porosity tool. Analytical and experimental research method of machining of the threaded holes in applying deforming tools based modeling of the process of forming a trumpet groove in blind holes deforming tool. Theoretically grounded possibility of the surface layer of quality blind holes after PPD alloy AK12M2. The new design tools and practical advice on selecting treatment regimes that ensure maximum processing efficiency deaf threaded holes. The economic effect of the introduction of the main provisions of the production of 18,207.44 UA.
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Абдулкерімов, Ілімдар Діляверович. "Технологічне забезпечення якості різьбових з'єднань у глухих отворах деталей з алюмінієвих сплавів деформуючим інструментом". Thesis, НТУ "ХПІ", 2016. http://repository.kpi.kharkov.ua/handle/KhPI-Press/20295.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.02.08 – технологія машинобудування. Національний технічний університет "Харківський політехнічний інститут", Харків, 2016.
Дисертація присвячена вирішенню проблеми технологічного забезпечення герметичності різьбових з'єднань деталей з алюмінієвих сплавів з газо-усадковою пористістю деформуючим інструментом. У роботі проведено аналіз існуючих систем обробки глухих отворів у деталях з газо-усадкових матеріалів. Проведено аналітичне та експериментальне дослідження методу механічної обробки різьбових отворів при застосуванні деформуючого інструменту з урахуванням моделювання процесу формоутворення трубних різьб у глухих отворах деформуючим інструментом. Розроблено конструктивні й технологічні параметри деформуючого інструменту для глухих отворів під трубну різьбу в деталях з алюмінієвих сплавів з газо-усадковою пористістю. Теоретично обґрунтовано можливість забезпечення якісного поверхневого шару глухих отворів після ППД сплаву АК12М2. Запропоновано нові конструкції інструменту та практичні рекомендації щодо вибору режимів обробки, що забезпечують високу ефективність обробки глухих різьбових отворів. Економічний ефект від упровадження основних положень роботи у виробництво становить 18207 грн.The thesis for the degree of candidate of technical sciences, specialty 05.02.08 - technology of mechanical engineering. National Technical University "Kharkiv Polytechnic Institute", Kharkov, 2016. The dissertation is devoted to the processing to ensure the tightness of threaded connections of details from aluminum alloys deformed gas shrinkage porosity tool. Analytical and experimental research method of machining of the threaded holes in applying deforming tools based modeling of the process of forming a trumpet groove in blind holes deforming tool. Theoretically grounded possibility of the surface layer of quality blind holes after PPD alloy AK12M2. The new design tools and practical advice on selecting treatment regimes that ensure maximum processing efficiency deaf threaded holes. The economic effect of the introduction of the main provisions of the production of 18,207.44 UA.
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Zhang, Yao. "Comportement hydrique et poro-mécanique des bétons à hautes performances Andra : influence de la microstructure." Thesis, Ecole centrale de Lille, 2014. http://www.theses.fr/2014ECLI0009/document.
Повний текст джерелаАнотація:
Cette thèse étudie la rétention d’eau à haute HR et le retrait sous température modérée des bétons CEMI et CEMV de l’Andra, en lien avec leur microstructure.Pour étudier l’origine des variations de Sw à haute HR, du béton est séché à HR= 92-100%. Pour les deux bétons, l’échantillonnage influe significativement sur Sw. Pour le CEMI, à HR=100%, la taille joue aussi, en lien avec un mécanisme de séchage par désorption de surface ; à HR=92&98%, ce béton n’est plus sensible aux effets de surface ; il est sensible aux conditions expérimentales. Pour le CEMV, l’effet de la taille existe quelle que soit l’HR, mais il est peu sensible aux conditions expérimentales.A partir de 60°C, le retrait de dessiccation présente quatre phases en fonction de la perte de masse relative. Pour le béton CEMI séché jusqu’en phase 3 ou 4, la possible rigidification de la matrice solide est investiguée par un essai couplé de poro-élasticité et transport de gaz. Pour un même échantillon en phase 3 puis en phase 4, on mesure une légère augmentation du Ks ; la perméabilité au gaz est significativement plus sensible au confinement. Par contre, la rigidification du matériau est limitée en comparaison de l’effet d’échantillonnage.Au MEB, les phases et la morphologie des bétons sont quantifiées. Le CEM I et le CEM V ont des phases solides identiques, mais le CEM V comprend des phases spécifiques (ajout de laitiers et cendres volantes). Les C-S-H du CEM V ont un rapport C/S globalement plus bas que le CEM I. Ce rapport reste similaire pour trois gâchées différentes. Par contre, l’occurrence de pores millimétriques varie significativement, du fait de modes de mise en oeuvre sensiblement différentsThis thesis focuses on water retention at high relative humidity (RH) (92-100%) and dessiccation shrinkage under moderate temperature (60-80°C) for two high performance concretes CEMI and CEMV (from Andra), in relation with their microstructure.To investigate the origins of the variations in water saturation degree Sw at high RH, both concretes are dried at RH=92, 98 and 100%, from the fully saturated state. For both concretes, sampling affects significantly Sw. For CEMI at 100%RH, sample size also affects Sw, due to surface drying (desorption); at 92 and 98%RH, CEMI is no longer sensitive to surface drying effects; it is sensitive to experimental conditions (RH, T). CEMV is affected by sample size whatever the RH, but not by experimental conditions.From 60°C drying temperature, the relationship between shrinkage and relative mass loss presents four distinct phases. CEMI concrete is dried at 65°C until phase 3 or 4, and then submitted to a coupled poro-mechanical and gas permeability test. For the same sample tested in phase 3 and then 4, a difference in solid skeleton incompressibility modulus Ks is measured, which is significantly lower than the differences in Ks due to sampling.With the Scanning Electron Microscope, the solid phases and morphology of both concretes are quantified. CEM I and CEM V comprise identical phases, even portlandite, yet CEM V concrete has some specific phases, owing to the addition of slag and fly ash. The C-S-H in CEM V have a lower C/S ratio than in CEM I. The (C/S) ratio remains similar when comparing between three different batches. Besides, millimetric pores vary significantly, owing to differences in manufacturing
Частини книг з теми "Gas shrinkage porosity"
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Kostin, I., A. Sidorov, S. Belyaev, A. Startsev, A. Krokhin, A. Krechetov, and A. A. Iliin. "Reducing Gas Shrinkage Porosity in Al–Mg Alloy Slabs." In The Minerals, Metals & Materials Series, 912–17. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65396-5_121.
Повний текст джерела
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Lee, Soon Gi, and Arun M. Gokhale. "Phenomena of Formation of Gas Induced Shrinkage Porosity in Pressure Die-Cast Mg-Alloys." In Essential Readings in Magnesium Technology, 211–16. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118859803.ch35.
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Lee, Soon Gi, and Arun M. Gokhale. "Phenomena of Formation of Gas Induced Shrinkage Porosity in Pressure Die-Cast Mg-Alloys." In Essential Readings in Magnesium Technology, 211–16. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-48099-2_35.
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Balasundaram, A., and A. M. Gokhale. "Digital Image Analysis Technique for Characterization of Shrinkage and Gas (Air) Porosity in Cast Magnesium Alloys." In Magnesium Technology 2001, 154–59. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118805497.ch28.
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"Shrinkage Porosity and Gas Porosity." In Casting, 370–74. ASM International, 2008. http://dx.doi.org/10.31399/asm.hb.v15.a0005222.
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Campbell, John. "Defects in Aluminum Alloy Castings." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000253.
Повний текст джерелаАнотація:
Most of the major defects in Al alloy castings are the result of entrainment processes. The entrainment of the surface of the liquid creates bifilm defects, and the entrainment of air creates bubbles and bubble trails. Occasionally the entrainment of foreign inclusions, such as sand inclusions, can also be a problem. Bifilms form the initiators of gas porosity, shrinkage porosity, hot tears, and cracks. Since bifilms can be controlled by improved melting and casting techniques, all these defects are controllable. In addition, bifilms control the mechanical properties of castings, particularly tensile elongation, toughness, and fatigue. The other important effects caused by bifilms such as invasive corrosion behavior including pitting, stress corrosion cracking, and possibly hydrogen embrittlement, are beyond the scope of this review.
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Dispinar, Derya. "Melt Quality Assessment." In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-120052503.
Повний текст джерелаАнотація:
It is well known that the reaction of liquid aluminum with the moisture in the environment results in two products: aluminum oxide and hydrogen gas that dissolves in aluminum. Both of these products are considered to be detrimental to the properties of aluminum alloys. Therefore, test equipment has been developed to check the levels of these defects in the melt. Many of these involve expensive and consumable tools. In addition, an experienced personnel may be required to interpret the results. Nonetheless, aluminum oxide is harmless as long as it remains on the surface. The problem begins when this oxide is entrained into the liquid aluminum such as turbulence during transfer or mold filling in a non-optimized design. This can only happen by folding of the oxide. During this action, rough surface of the oxides comes in contact to form no bonds. These defects are known as bifilms that have certain characteristics. First, they act as cracks in the cast parts since they are oxides. It is important to note that aluminum oxide has thin amorphous oxide (known as young oxides) and thick crystalline oxide (γ-Al2O3) that may be formed in a casting operation. Second, almost zero force is required to open these bifilms due to the unbonded folded oxide skins. Thus, these defects can easily form porosity by unravelling during solidification shrinkage. On the other hand, the formation of porosity by hydrogen is practically impossible. Theoretically, hydrogen has high solubility in the liquid but it has significantly low solubility in solid aluminum. Thus, it is suspected that hydrogen is rejected from the solidification front to form hydrogen gas and porosity. However, the hydrogen atom has the smallest atomic radii and high diffusibility. Therefore, segregation of hydrogen in front of the growing solid is difficult. In addition, the energy required for hydrogen atoms to segregate and form hydrogen gas molecule is around 30,000 atm. Under these conditions, porosity formation by hydrogen is not likely to be achieved. Hydrogen probably stays in a supersaturated state or diffuses homogeneously through the cast part. The effect of hydrogen can only be seen when it can diffuse into the unbonded gap between the bifilms to open them up to aid the unravelling of bifilms to form porosity. This phenomenon can be easily detected by a very simple test called reduced pressure test. When a sample is solidified under vacuum, the bifilms start to open up. Since all porosity is formed by bifilms, the cross section of the sample solidified under vacuum can be analyzed by means of image analysis software. The sum of maximum length of pores can be measured as an indication of melt quality. Since bifilms are the most detrimental defects, this value is called “bifilm index” given in millimetres, which makes this test the only test that can quantify aluminum melt quality in such detail including both the effects of bifilms and hydrogen together. Several Al-Si alloys were used at various conditions: degassing with lance, ceramic diffusers, and graphite rotary has been compared. Gravity sand casting, die casting, and low-pressure die casting methods were evaluated. The effect of grain refiners and modifiers was studied. And the evolution of the bifilm index has been presented.
Тези доповідей конференцій з теми "Gas shrinkage porosity"
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Shenefelt, Jeffrey R., Rogelio Luck, John T. Berry, and Robert P. Taylor. "Solidification Modeling and Porosity Control in Aluminum Alloy Castings." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0710.
Повний текст джерелаАнотація:
Abstract Commercial software packages enable the thermal environment of shaped castings to be determined provided the boundary conditions are well understood. Criteria functions (CF’s) based on the thermal environment provide a means for estimating shrinkage porosity within a casting. However, the CF’s do not account for gas driven porosity forming within the casting. This paper reviews the CF’s and additional approaches to account for hydrogen evolution in aluminum-copper and aluminum-silicon alloys.
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Chen, H., M. Li, Y. Zhang, C. Liu, and Y. Li. "Productivity Prediction of Coalbed Methane Considering the Permeability Changes in Coal." In SPE Energy Resources Conference. SPE, 2014. http://dx.doi.org/10.2118/spe-169922-ms.
Повний текст джерелаАнотація:
AbstractThis paper describes a three-dimensional numerical model for predicting the coalbed methane (CBM) production. The model describes single phase gas desorption from coal matrix, diffusion to the fracture and two-phase flow of gas and water in the natural fracture system as well as the permeability changes in coal which result from effective stress changes and matrix shrinkage due to gas desorption. The model was discretized by a finite difference method. The implicit pressure-explicit saturation (IMPES) method was used to solve the two-phase flow equations and gas desorption equation was solved implicitly.The numerical model was validated by the field data from Qinshui basin in China. Based on the model, the impact of various reservoir and Langmuir isothermal adsorption parameters on the gas production was investigated.The results show that the gas production rate of the coalbed methane predicted by this model is in good accordance with the field data. The permeability near the wellbore dramatically decreases as the reservoir pressure drops at the early production period while at the later production period, the permeability near the wellbore increases because of the matrix shrinkage. The permeability changes far away from the wellbore are not so remarkable. In addition, the gas production rate increases with the increased permeability, seam thickness and Langmuir pressure constant while it decreases with the increased porosity and Langmuir volume constant.The numerical model can be used to predict and analyze the production performance of CBM reservoirs and the research results provide theoretical support for CBM production.
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Shipley, James, Chad Beamer, and Johannes Gårdstam. "Recent Developments in The Use of Hip for The Offshore Industry." In Offshore Technology Conference. OTC, 2021. http://dx.doi.org/10.4043/31252-ms.
Повний текст джерелаАнотація:
Abstract The use of additive manufacturing (AM) technology is growing rapidly for offshore use, whilst established production technologies such as powder metallurgy near-net-shape (PM-NNS) continue to be used. New standards are being introduced and many of the oil and gas majors are now developing supply chains to ensure rapid supply of high-quality complex parts. Environmental concerns are helping to drive this with use of near-net-shape technologies to reduce carbon dioxide emissions through more efficient designs and metal forming methods. Hot isostatic pressing (HIP) has been used to remove shrinkage porosity and internal defects in cast products for many years, predominantly to improve mechanical properties and fatigue resistance. Recently, there has been an increasing focus on AM processes for demanding applications where localized corrosion and similar internal defects and porosity are a concern. HIP technology is being used to either produce PM-NNS parts, or for the post processing of AM produced components to ensure defect free material prior to service in demanding environments. This paper will present a broad overview in the use of HIP equipment to produce parts and components to the offshore industry.
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Moeini Sedeh, Mahmoud, and J. M. Khodadadi. "Effect of Marangoni Convection on Solidification of Phase Change Materials Infiltrated in Porous Media in Presence of Voids." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17316.
Повний текст джерелаАнотація:
Void formation is encountered in the form of air pockets during preparation of composite thermal energy storage systems, consisting of phase change materials (PCM) infiltrated into a high-conductivity porous structure. The presence of voids within the pores of a porous structure degrades the thermal and phase change behavior of such composites. Recent work devoted to multiphase modeling of the infiltration of PCM in liquid state into porous media and formation of voids showed that among the various contributing driving forces (i.e. gravity, pressure gradient and interfacial forces), the interfacial forces (resulting from surface tension and contact angle) play a significant role at the pore level. Additionally, modeling the solidification and melting of PCM within the pores in presence of a void revealed that there is a temperature gradient along the interface between the PCM and void. Considering the surface tension as the major driving force at the pore level, this temperature gradient is large enough to give rise to a gradient in surface tension that then triggers the Marangoni convection at the interface. Thus, as a convection mechanism, it affects the phase change process as well as the interface shape. Therefore, in this paper, the effects of the Marangoni convection on PCM solidification time and shape of the interface was investigated at the pore level. A numerical approach was employed for solidification of a PCM based on the combination of the Volume-of-fluid (VOF) and enthalpy-porosity methods, including the variation of the surface tension with temperature, i.e. Marangoni effects. A two-dimensional model of a pore was developed based on the average geometric features of the pores in a porous structure with interconnecting pores. Following the grid independence study, the transient simulation of solidification was performed, whereas the PCM within the pore and the air within the void were treated as incompressible liquid and compressible gas, respectively. The liquid density change during the solidification was included to explicate the formation of shrinkage void and its distribution within the pores. The PCM solidification time and shape of the final interface between the PCM and air pocket (representing the amount and distribution of the shrinkage void evolving during the solidification) were extracted and compared between the cases with and without Marangoni convection. For verification purposes, the volume of the predicted infiltration void is in agreement with experimental measurements and the volume of the shrinkage void shows a good agreement with theoretical volume change. The final shape of the interface was justified and turned out to be in agreement with the prevailing Marangoni convection pattern.
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Sricharoenchaikul, Viboon, and Duangduen Atong. "Thermal Conversion Characteristic of Pelletized Jatropha Residue and Glycerol Waste." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90223.
Повний текст джерелаАнотація:
Adverse environmental effects resulting from fossil fuel usage as well as foreseeable conventional energy depletion lead to the exploration of alternative fuel materials especially the renewable ones. In this work, characterization of synthetic fuel material formed by pelletization of Jatropha residue (physic nut) using glycerol waste as a binder was carried out in order to investigate the feasibility of utilizing these waste materials as another renewable energy source. Both wastes are by products from biodiesel manufacturing process. Synthetic fuel materials of Jatropha residue mixed with 0–50% glycerol waste were formed to length of about 11 mm and diameter of about 13 mm under pressure of 7 MPa in a hydraulic press. Maximum compressive stress (2.52×105 N/m2) of the fuel pellet occurred at 10% glycerol waste. Thermal conversion characteristic of solid fuel was studied by using single particle reactivity testing scheme at temperature of 500–900°C under partial oxidation atmosphere. In general, higher glycerol content in solid fuel as well as oxygen concentration in reacting gas resulted in greater decomposition rate from 0.006–0.110 g/sec. Burning started with a relative short drying phase, followed with a longer pyrolysis time and thereafter the dominated char combustion time which took around 35–57% of total conversion time. The average total conversion time varied from 26 to 288 sec, depended mainly on reaction temperature. Higher glycerol content resulted in char with lower density and higher shrinkage with greater porosity. Greatest changes in pellet diameter, height, and density of 75.6%, 89.2%, and 91.5%, respectively, were exhibited at 5% oxygen atmosphere and 900°C. The results suggested that Jatropha residue mixed with glycerol is suitable for utilization as quality solid fuel.
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Zunjarrao, Suraj C., Abhishek K. Singh, and Raman P. Singh. "Structure-Property Relationships in Polymer Derived Amorphous/Nano-Crystalline Silicon Carbide for Nuclear Applications." In 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89515.
Повний текст джерелаАнотація:
Silicon carbide (SiC) is a promising candidate for several applications in nuclear reactors owing to its high thermal conductivity, high melting temperature, good chemical stability, and resistance to swelling under heavy ion bombardment. However, fabricating SiC by traditional powder processing route generally requires very high temperatures for pressureless sintering. Polymer derived ceramic materials offer unique advantages such as ability to fabricate net shaped components, incorporate reinforcements and relatively low processing temperatures. Furthermore, for SiC based ceramics fabricated using polymer infiltration process (PIP), the microstructure can be tailored by controlling the processing parameters, to get an amorphous, nanocrystalline or crystalline SiC. In this work, fabrication of polymer derived amorphous and nano-grained SiC is presented and its application as an in-core material is explored. Monolithic SiC samples are fabricated by controlled pyrolysis of allylhydridopolycarbosilane (AHPCS) under inert atmosphere. Chemical changes, phase transformations and microstructural changes occurring during the pyrolysis process are studied as a function of the processing temperature. Polymer cross-linking and polymer to ceramic conversion is studied using infrared spectroscopy (FTIR). Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) are performed to monitor the mass loss and phase change as a function of temperature. X-ray diffraction studies are done to study the intermediate phases and microstructural changes. Variation in density is carefully monitored as a function of processing temperature. Owing to shrinkage and gas evolution during pyrolysis, precursor derived ceramics are inherently porous and composite fabrication typically involves repeated cycles of polymer reinfiltration and pyrolysis. However, there is a limit to the densification that can be achieved by this method and porosity in the final materials presents difficulties in interpreting “true” properties from bulk measurements. Hence, hardness and modulus measurements are carried out using instrumented nanoindentation to establish property–structure relationship for SiC derived from the polymer precursor. It is seen that the presence of nanocrystalline domains in amorphous SiC significantly influences the modulus and hardness.
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Dibua, Obehi G., Anil Yuksel, Nilabh K. Roy, Chee S. Foong, and Michael Cullinan. "Nanoparticle Sintering Model, Simulation and Calibration Against Experimental Data." In ASME 2018 13th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/msec2018-6383.
Повний текст джерелаАнотація:
One of the limitations of commercially available metal Additive Manufacturing (AM) processes is the minimum feature size most processes can achieve. A proposed solution to bridge this gap is microscale selective laser sintering (μ-SLS). The advent of this process creates a need for models which are able to predict the structural properties of sintered parts. While there are currently a number of good SLS models, the majority of these models predict sintering as a melting process, which is accurate for microparticles. However, when particles tend to the nanoscale, sintering becomes a diffusion process dominated by grain boundary and surface diffusion between particles. As such, this paper presents an approach to model sintering by tracking the diffusion between nanoparticles on a bed scale. Phase Field Modeling (PFM) is used in this study to track the evolution of particles undergoing sintering. Part properties such as relative density, porosity, and shrinkage are then calculated from the results of the PFM simulations. These results are compared to experimental data gotten from a Thermogravimetric Analysis done on dried copper nanoparticle inks, and the simulation constants are calibrated to match physical properties.
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Lasne, Patrice, Mickael Barbelet, Olivier Jaouen, Frederic Costes, Ihab Ragai, and Harry Tempelman. "Simulation of the Heat Treatment of an Automotive Cast Part." In ASME 2010 International Manufacturing Science and Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/msec2010-34152.
Повний текст джерелаАнотація:
In this paper, simulation of the casting and heat treatment processes of front spindle of a rigid dump truck are presented. The objectives are to present how the different operations can be simulated in order to predict the local phases in the different areas of the part. To reach these objectives, two software packages are used in sequenced. The first one, Thercast, is used to simulate the casting operation. The second one, Forge, is applied to the water-quenching simulation. The general formulations used are shortly presented in this paper. The aim of casting simulation is to compute the metal behavior from the liquid state at the pouring stage to the solid state during cooling into the mold. Filling and cooling phases simulations, taking into account the air gap, ensure that no internal defects like shrinkage, porosity, micro porosity or hot tearing are taking place into the part. Forge software allows the water quenching stage simulation. A model is used to deduct the IT diagram (Isothermal Transformation diagram) from the material composition. The initial grain size influences the transformation kinetics. Another main phenomenon is the efficiency of the cooling bath. The results of the simulation (phase distribution, distortion, residual stresses) strongly depend on these input conditions. Thus, the effect of input data variations on final results must be studied. The modeling approach is validated by comparisons with micrographic observations. Another solution to determine the reliability of the models is to observe the local properties in the quenched part. The prediction of the local micro hardness can be used to evaluate the accuracy of the quenching models.