• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.126-129
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• 2009

In this study, it was aimed to develop the re-use technology of ultra-fine silicon powders, by-products during the current production process of high purity poly-Si feedstock. For this goal, the compacts of the silicon powders were tried to fabricate by CIP (Cold Isostatic Pressing) method using silicon rubber mold without chemical binder materials. The density ratio of the silicon powder compacts reached 74%. In order to simulate the actual handling and charging conditions of feedstock material in casting process, a shaking test was carried out and mass loss measured. Finally, the silicon powder compacts were melted using a cold crucible induction melting method and the purity assessment was conducted by Hall effect measurement.

• Journal of Powder Materials
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• v.4 no.2
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• pp.90-99
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• 1997

Densification behavior and grain growth of tool steel powder compacts during pressureless sintering, sinter forging, and hot isostatic pressing were investigated. Experimental data were compared with results of finite element calculations by using the constitutive model of Abouaf and co-workers and that of McMeeking and co-workers. Densification and deformation of tool steel powder compacts were studied by implementing power-law creep, diffusional creep, and grain growth into the finite element analysis. The shape change of a powder compact in the container during hot isostatic pressing was also studied. The theoretical models did not agree well with experimental data in sinter forging, however, agreed well with experimental data in hot isostatic pressing.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.66-69
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• 2000

In order to analyze the densification behaviour of stainless steel powder compacts during hot isostatic pressing (HIP) at elevated temperatures, a power-law creep constitutive model based on the plastic deformation theory for porous materials was applied to the densification. Various densification mechanisms including interparticle boundary diffusion, grain boundary diffusion and lattice diffusion mechanisms were incorporated in the constitutive model, as well. The power-law creep model in conjunction with various diffusion models was applied to the HIP process of 316L stainless steel powder compacts under 50 and 100 MPa at 1125 $!`\acute{\dot{E}}$. The results of the calculations were verified using literature data It could be found that the contribution of the diffusional mechanisms is not significant under the current process conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.735-742
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• 2000

Densification behaviors of mixed metal powder under high temperature were investigated. Experimental data of mixed copper and tool steel powder with various volume fractions of Cu powder were obtained under hot isostatic pressing and hot pressing. By mixing the creep potentials of McMeeking and co-workers and of Abouaf and co-workers originally for pure powder, the mixed creep potentials with various volume fractions of Cu powder were employed in the constitutive models. The constitutive equations were implemented into a finite element program (ABAQUS) to compare with experimental data for densification of mixed powder under hot isostatic pressing and hot pressing. Finite element calculations by using the creep potentials of Abouaf and co-workers agreed reasonably well with experimental data, however, those by McMeeking and co-workers underestimate experimental data as observed in the case of pure metal powders.

• Economic and Environmental Geology
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• v.12 no.1
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• pp.17-28
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• 1979

Geodetic and geophysical quantities related to gravity data are analyzed using three-dimensional sin x/x method for the southern part of the Korean peninsula and adjacent Japan Sea. The thickness of isostatic crust is found as 26 km. The average isostatic gravity anomaly in this area is appeared to be +24.8 mgal, of which result indicates that the surface features are under-compensation or the thickness of the crust is thinner than normal. It is noteworthy that the general trend of the deflections of the vertical in direction is nearly perpendicular to the geological structure having a direction of NNE-SSW in the southern part of Korea.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.652-657
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• 2001

Densification behavior of aluminum alloy(A16061) powder was investigated under cold compaction. Experimental data were obtained under triaxial compression with various loading conditions. A special form of the Cap model was proposed from experimental data of A16061 powder under triaxial compression. The proposed yield function and several yield functions in the literature were implemented into a finite element program (ABAQUS) to compare with experimental data for densification behavior of A16061 powder under cold isostatic pressing and die compaction. The agreement between finite element calculations from the proposed yield function and experimental data is very good under cold isostatic pressing and die compaction.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.1
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• pp.95-104
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• 2002

Densification behavior of aluminum alloy(A16061) powder was investigated under cold compaction. Experimental data were obtained under triaxial compression with various loading conditions. A special form of the Cap model was proposed from experimental data of A16061 powder under triaxial compression. The proposed yield function and several yield functions in the literature were implemented into a finite element program (ABAQUS) to compare with experimental data for densifcation behavior of A16061 powder under cold isostatic pressing and die compaction. The agreement between finite element calculations from the proposed yield function and experimental data is very good under cold isostatic pressing and die compaction.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.663-664
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• 2006

Sintered Ti(C,N)-based cermets were treated with hot isostatic pressing (HIP) at different nitrogen pressures. The tribological properties of the treated cermets have been evaluated. The results show that a hard near-surface area rich in TiN formed after HIP treatment. The cermets treated at higher pressure had a relatively lower friction coefficient and specific wear rate. In all cases the microhardness of treated cermets is higher than that without HIP natridation. The wear mechanisms of cermets were hard particle flaking-off and ploughing. It was also found that the HIP natridation is well-suited for improving the tribological properties of cermets.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.10a
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• pp.131-138
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• 1996

A new yield criterion for metal powder compaction based on continuum mechanics has been proposed. It includes three parameters to characterize the geometrical hardening of powder compact and strain hardening of incompressible metal matrix. The elasto-plastic finite element method to describe compaction of metal powders has been formulated using the new yield criterion. The values of parameters in the yield criterion can be determined using cold isostatic pressing(CIP). The finite element method can simulate compaction behavior of various copper powders.

• Korean Journal of Materials Research
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• v.12 no.8
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• pp.634-640
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• 2002

To improve the ductility of mTEX>$(Al +12.5%Cu)<_3$Zr intermetallics, which are the potential high temperature structural materials, the mechanical alloying behavior, the effect of pressure and temperature on the $Ll_2$, phase formation and the behavior of the cold isostatic press and sintering were investigated. However mechanically alloyed A1$_3$Zr alloy have been known to have high mechanical strength even at high temperature, its workability was poor. A method of solution is refined grain size and phase transformation from $DO_{23}$ to $Ll_2$.$ Ll_2$ structure TEX>$(Al+12.5%Cu)<_3$Zr with nanocrystalline microstructure intermetallic powders where were prepared by mechanical alloying of elemental powders. Grain sizes of the as milled powders were less than 10nm (from transmission electron microscopy, TEM). Thermal analyses showed that $Ll_2$ structure was stable up to$ 800^{\circ}C$ for 1hour $(Al+ 12.5%Cu)<_3$Zr. $(Al+12.5%Cu)<_3$Zr has been consolidated by cold isostatic pressing (CIP 138, 207, 276, 414MPa) at room temperature and subsequent heat treatment at high temperatures where $Ll_2$ structure was stable under vacuum atmosphere. The results showed that 94.2% density of Ll$_2$ compacts was obtained for the (Al +12.5%Cu)$_3$Zr by sintering at 80$0^{\circ}C$ for 1hour (under CIPed 207MPa). This compact of the grain size was 40nm.