• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.185-186
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• 2006

Numerical Simulation of powder die pressing is conducted on Case Study geometry. Influence of fill density distribution and punch kinematics upon green density distribution and punch loading are studied and discussed. Deviations in punch kinematics due to punch deflection influence the most the results in term of density and force.

• 대한기계학회논문집A
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• 제28권8호
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• pp.1140-1151
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• 2004

This paper reports on the finite elements analysis for die compaction process of cemented carbide tool parts. Experimental data were obtained under die compaction and triaxial compression with various loading conditions. The elastoplastic constitutive equations based on the yield function of Shima and Oyane were implemented into an explicit finite element program (ABAQUS/Explicit) and implicit finite element program (PMsolver/Compaction-3D) to simulate compaction response of cemented carbide powder during die compaction. For simulation of die compaction, the material parameters for Shima and Oyane model were obtained by uniaxial die compaction test. Explicit finite element results were compared with implicit results for cemented carbide powder.

• 한국재료학회지
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• 제18권8호
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• pp.411-416
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• 2008

In this research, fine-structure TiO2 bulks were fabricated in a combined application of magnetic pulsed compaction (MPC) and subsequent sintering and their densification behavior was investigated. The obtained density of $TiO_2$ bulk prepared via the combined processes increased as the MPC pressure increased from 0.3 to 0.7 GPa. Relatively higher density (88%) in the MPCed specimen at 0.7 GPa was attributed to the decrease of the inter-particle distance of the pre-compacted component. High pressure and rapid compaction using magnetic pulsed compaction reduced the shrinkage rate (about 10% in this case) of the sintered bulks compared to general processing (about 20%). The mixing conditions of PVA, water, and $TiO_2$ nano powder for the compaction of $TiO_2$ nano powder did not affect the density and shrinkage of the sintered bulks due to the high pressure of the MPC.

• 한국분말재료학회지
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• 제7권1호
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• pp.42-49
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• 2000

Densificationbehavior of conventional austenitic stainless steel powder compacts was studied by comparing the relative density of sintered compact(Ds)with that of green compacts(Dg)prepared with various catbon contents and P/M process. Dg of 304and 316 powders by warm compaction under pressure of 686 MPa at heating temperature of powder(553K) and dies (573K) were 80% and 81%, repectively, whichwere 2 and 3% higher than those of conventional green compacts at the same pressure. Ds of 304 compacts sintered at 1373K in H2 gas has the same value of 84% max. regardless of compacting temperature, and Ds of 316 compacts at the same sintering conditions were 80% by conventional compaction and 83% by warm compaction. Oxygen contents of 304 and 316 sintered compacts were increased 1.43∼2.94% and 0.010∼0.921% higher than those of raw powders and warm green compacts, respectively. In other case, Ds of 316 compacts sintered at 1573K in vacuum had the same value of 86%max. And Ds of 316 compacts at the same sintering conditions were 83% and 86% by conventional and warm compaction, respectively. Oxygen contents of 304 sintered compacts were 0.321% and 0.360%, and in case of 316, they were 0.419% and 0.182% by the respective compating condition. With carbon additions in the range 0.1∼0.6% Ds increased to the extent of 86∼89% in 304 sintered compacts, and to 82∼84% and 85∼87% in 316 according to different two compacting peocesses compared to those of sintered compacts without carbon addition.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.203-204
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• 2006

There is an increasing demand for PM-processes with the capability to produce parts of higher complexity than with conventional press and sinter technology in high production numbers. Warm-flow-compaction (WFC) makes use of improved flowability of powders when blended in an appropriate ratio with fine powder fractions and lubricating binders. Here the process is shown with examples of PM-Steels. General features possible with the process like pressing of undercuts and threaded bores are shown.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.20-21
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• 2006

Through different projects, CETIM and its scientific and industrial partners have evaluated the potential of the High Velocityy Compaction Technology in terms of materials and component shape. Various kinds of powder materials were studied: metals, ceramics and polymers. The HVC process was used with success to manufacture gears, large parts and multilevel components. Due to the high density of HVC parts, the green machining process enables shapes to be produced that would otherwise be impossible to compact and components to be produced with very hard sintered and homogeneous materials.

• 한국세라믹학회지
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• 제30권2호
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• pp.157-163
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• 1993

Hot pressing after cold cyclic compaction of Al2O3 powder mixtures containing SiC whiskers or Al2O3 short fibers is studied with emphasis on the effects of cold cyclic compaction. The green density of the mixtures increases as the cycle number increases and the cyclic pressure becomes higher. The higher green density is also obtained by cold cyclic compaction with the lower pressrue than a single stroke cold compaction. To achieve a higher densification during hot pressing, cold cyclic compaction before hot pressing is more efficient compared to the conventional hot pressing process (without cold cyclic compaction). Moreover, a low cyclic pressure did not affect on toughening mechanism by whisker reinforcement.

• 대한기계학회논문집A
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• 제22권4호
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• pp.924-938
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• 1998

Densification behavior of ceramic powder under cold compaction was investigated. Experimental data were obtained for zirconia powder and alumina powder under triaxial compression with various loading conditions. A special form of the Cap model was proposed from experimental data under triaxial compression for a yield function of ceramic powder. The proposed yield function was inplemented into a finite element program (ABAQUS) to study densification behaviors of zirconia and alumina powders under die compaction. The effect of friction between the powder and die wall was also investigated. Density distributions of powder compacts were measured and compared with finite element results.

• Nuclear Engineering and Technology
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• 제34권1호
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• pp.60-67
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• 2002

The effects of ball-milling time(0 ~4 hrs) have been investigated on the change of powder characteristics, compaction behavior (compaction pressure range : 200 ~400MPa) and sinterability (1700'c in Ha atmosphere) of two different UO$_2$ powders (ex-ADU and ex-AUC) prepared by the wet process. It is observed that, while the ex-ADU UO$_2$ was little affected, the ex-AUC UO$_2$ was largely affected by the ball-milling treatment. This may be attributed to the characteristics of particle size formed during the preparation step, i.e.., the former has a small average size of about 1.0${\mu}{\textrm}{m}$, while the latter has a relatively large average size of about 301n. It appeared that the effective size reduction by ball-milling treatment is limited to the particle size larger than l${\mu}{\textrm}{m}$, and to the extent of maximum decrease in size of about 0.5tn. In the case of ex-AUC UO$_2$, it is observed that the particle size decreased with ball-milling time and green density and sintered density of the pellets prepared from ball-milled powder increased compared with those of pellets prepared from the as-received powder under the same conditions. This may be attributed mainly to the fine particles formed during the ball-milling treatment.

• 한국분말재료학회지
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• 제12권1호
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• pp.24-29
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• 2005

Nano Fe-6.5wt%Si powders have been synthesized by mechano-chemical process (MCP) for an application of soft magnetic core. Owing to hard and brittle characteristics of Fe-6.5Si nano powders having large surface area, it is very difficult to reach high density more than 70% of theoretical density (~7.4 g/$cm_3$) by cold compaction. To overcome such problem a magnetic pulsed compaction (MPC), which is one of dynamic compaction techniques, was applied. The green density was achieved about 78% (~5.8 g/$cm_3$) by MPC at room temperature.