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Sintering Multi-scale Virtual Reality
Olevsky Eugene A. 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
The directions of further developments in the modeling of sintering are pointed out, including multi-scale modeling of sintering, on-line sintering damage criteria, particle agglomeration, sintering with phase transformations. A true multi-scale approach is applied for the development of a new meso-macro methodology for modeling of sintering. The developed macroscopic level computational framework envelopes the mesoscopic simulators. No closed forms of constitutive relationships are assumed for the parameters of the material. The model framework is able to predict the final dimensions of the sintered specimen on a global scale and identify the granular structure in any localized area for prediction of the material properties.
Tailored Powder Composites by Freeze Drying, Electrophoretic Deposition and Sintering
Olevsky Eugene A.,Wang Xuan 한국분말야금학회 2006 한국분말야금학회 학술대회논문집 Vol.2006 No.1
Two approaches for the fabrication of tailored powder composites with specially distributed pore-grain structure and chemical composition are investigated. Electrophoretic Deposition (EPD) followed by microwave sintering is employed to obtain functionally graded materials (FGM) by in-situ controlling the deposition bath suspension composition. and zeolite FGM are successfully synthesized using this technique. In order to fabricate an aligned porous structure, unidirectional freezing followed by freeze drying and sintering is employed. By controlling the temperature gradient during freezing of powder slurry, a unidirectional ice-ceramic structure is obtained. The frozen specimen is then subjected to freeze drying to sublimate the ice. The obtained capillary-porous ceramic specimen is consolidated by sintering. The sintering of the graded structure is modeled by the continuum theory of sintering.
Sintering and Microstructure Characteristics of 42CrMo4 Steel Processed by Spark Plasma Sintering
Ridvan Yamanoglu,William Bradbury,Eugene A. Olevsky,Randall M. German 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.5
Rapidly solidified micron sized 42CrMo4 steel powder with a size range of 150-250 μm produced by plasma rotating electrode process was consolidated using a recently developed spark plasma sintering (SPS) process. The relationship between sintering parameters (temperature and soaking time) and microstructural properties was investigated. The effect of slow and high heating regimes on the consolidation of sintered compacts has been also investigated. Maximum relative density (99.2%) was obtained at 1000 °C, under 50 MPa pressure, with 8 min holding time and 200 °C/min heating rate. The microstructure of sintered steel was influenced by carburization occuring inside the graphite SPS process die. The diffusion of carbon produced martensite structure near the surface region and hardened the surface. This effect was investigated in detail using optical microscopy and hardness measurement. Scanning electrone microscopy was also used to examine the fracture surface of sintered compacts. High heating rate promoted the relative density at low temperature compared to high temperature.