• Journal of Powder Materials
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• v.9 no.4
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• pp.203-210
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• 2002

A new PIM in-process joining technique has been developed for more complicated and functional PIM components by application of the exuded wax from the green compacts during solvent debinding step. At first, various stainless steels and iron compacts with rectangular shape were combined, and the joining behaviors and properties were investigated by shear and tensile test, and microscopic observation. Subsequently, perfect joined three pieces of thin and hollow compacts were obtained for the combination of same and different stainless steels, and it was difficult to join the iron and stainless steel compacts in hydrogen atmosphere because of the different starting temperature of shrinkage. However, pretty good joined iron and stainless steel compacts were obtained by consideration of particle size and vacuum atmosphere. Finally, for the combination of ferro-silicon and austenitic stainless steel compacts, high functionality (magnetic (1.60Tes1a) & non-magnetic) and perfect joint were obtained.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1187-1188
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• 2006

This paper compares the effect of using different types of iron powders for the preparation of $Sm_2Fe_{17}$ by calciothermic reduction-diffusion (CRD). Three types of iron powder were used: carbonyl, sponge and water atomized. The results show that, when immediately nitrogenated after the CRD process, $Sm_2Fe_{17}$ prepared from sponge and water atomized iron powders yield $Sm_2Fe_{17}N_3$-magnets with a high degree of texture. However, after a suitable treatment with hydrogen followed by nitrogenation, $Sm_2Fe_{17}$-powders made from Carbonyl iron produce magnets with the best quality regarding coercivity, remanence and degree of texture.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1284-1285
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• 2006

We reported a P/M soft magnetic material with core loss value of $W_{10/1k}=68W/kg$, which is lower than that of 0.35mm-thick laminated material, by using high purity gas-atomized iron powder. Lack of mechanical strength and high cost of powder production are significant issues for industrial use. In order to achieve both low core loss and high strength by using inexpencive powder, the improvement of powder shape and surface morphology and binder strength was conducted. As the result, the material based on water-atomized powder with 80 MPa of TRS and 108 W/kg of core loss (W10/1k) was achieved.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.790-791
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• 2006

The fracture behavior and mechanical characteristics of sintered rare-earth magnets were investigated. It shows that the fracture behavior and bending strength of the magnets obviously exhibit anisotropy. Sm-Co magnets tend to cleavage fracture in the close-packed (0001) plane or in the ($10\bar{1}1$) plane. The fracture mechanism of $Nd_2Fe_{14}B$ magnet mainly appears to be intergranular fracture. The anisotropy of fracture behavior and mechanical strength of sintered rare-earth magnets is caused mainly by the strong crystal-structure anisotropy and the grain alignment texture. The effects of Nd content, and Pr, Dy substitution on the impact stability of $Nd_2Fe_{14}B$ magnets were also reported.

• Journal of Powder Materials
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• v.18 no.3
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• pp.221-225
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• 2011

In the current study, the effects of particle size on compaction behavior of water-atomized pure iron powders are investigated. The iron powders are assorted into three groups depending on the particle size; 20-45 ${\mu}M$, 75-106 ${\mu}M$, and 150-180 ${\mu}M$ for the compaction experiments. The powder compaction procedures are processed with pressure of 200, 400, 600, and 800 MPa in a cylindrical die. After the compaction stage, the group having 150-180 ${\mu}M$ of particle size distribution shows the best densification behavior and reaches the highest green density. The reason for these results can be explained by the largest average grain size in the largest particle group, due to the low plastic deformation resistance in large grain sized materials.

• Journal of Powder Materials
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• v.1 no.2
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• pp.181-189
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• 1994

The compacts of pure and phosphorus-coated iron powder with 0~0.8%C were sintered at $1100^{\circ}C$ for 40 min. in cracked ammonia gas atmosphere. The tensile and impact strengths were measured and the relationship of the results with carbon content, phosphorus, quenching and tempering was investigated. The results obtained can be summarized as follows : (1) The tensile strength of sintered compacts increased slowly with carbon content. Increase in tensile strength by heat treatment was evident especially in the low carbon specimen. The specimen with phosphorus showed higher strength compared to pure iron compacts value. (2) No inflection point of elasticplastic deformation on stress-strain curve was observed in sintered steel. The elastic modulus of sintered steel had the same tendency as tensile strength. But the elongation showed the opposite tendency. (3) The impact absorption energy of sintered steel without addition of phosphorus decreased successively with carbon content and by quenching and tempering. On the contrary, addition of phosphorus resulted in an increase of the impact absorption energy. Quenching and tempering did not affect the impact energy especially in high carbon content. (4) The main fracture source was pore in specimen and the propagation of crack occured mostly along the grain boundaries. But the intragranular fracture was also observed in high carbon, quenched and tempered specimen, and especially in the specimen with phosphorus.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1995.04a
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• pp.18-18
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• 1995

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2005.11a
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• pp.59-60
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• 2005

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.996.1-996.1
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• 2006

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2002.04b
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• pp.48-50
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• 2002

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