• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1995년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
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• pp.36-36
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• 1995

• 한국세라믹학회지
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• 제43권11호
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• pp.700-702
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• 2006

We prepared a Ni-ferrite encapsulated Mo-permalloy powder through simple electroless plating and heat treatment. It was observed that Ni-ferrite particles formed in a spherical form on each Mo-permalloy grain. The microstructure and the magnetic characteristics of the encapsulated powders depended strongly on oxidation time in the heat-treatment. When the powder was oxidized for 60 min, a dense Ni-ferrite layer covered the Mo-permalloy grain, which in turn exhibited high saturation magnetization of 85.8 emu/g. The magnetic core prepared additionally with the encapsulated powder exhibited a resonant frequency of 12 kHz.

• 대한금속재료학회지
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• 제50권6호
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• pp.445-448
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• 2012

We studied the effect of temperature and reaction time by investigating the various temperatures and reaction times in the reduction of molybdenum oxide ($MoO_3$) to molybdenum (Mo) powder in hydrogen gas. We also studied the effect of the reaction of reduction according to the various hydrogen gas flow rates. We surveyed the reduction from molybdenum oxide to molybdenum powder in hydrogen gas and checked two temperature ranges, one from $400^{\circ}C$ to $600^{\circ}C$ and the other from $700^{\circ}C$ to $900^{\circ}C$. We found that the reaction ratio of molybdenum oxide increased with an increasing temperature and also increased with an increasing reaction time, but hydrogen gas did not influence the reduction ratio of molybdenum oxide. We examined molybdenum powders fabricated by ball milling for two hours, using with X-ray diffraction (XRD) and a scanning electron microscopy (SEM).

• 한국재료학회지
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• 제8권3호
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• pp.206-213
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• 1998

순첨분말에 $(CuNO_3)_2$, $Ni(NO_3)_2)_2$, $(NH_4)_6Mo_7O_{24}$를 이온확산시켜 부분확산합금강분으로 제조하고, Cu, Ni, Mo의 함량에 따른 성형성, 소결성, 기계적특성을 조사하였다. 연구결과 각각 Cu 1.50wt%, Ni 1.75wt%, Mo 0.50wt%일 때, 경도 및 인장강도는 우수하고, 수축률의 변화는 거의 없음을 알 수 있었다. 이러한 결과를 이용하여 Cu 1.50wt%, Ni 1.75wt%, Mo 0.50wt%가 함께 이온확산된 부분합금강분을 제조하여 특성을 조사하고, 스웨덴의 Hoganas사에서 수입되고 있는 부분합금강분(distalloy AB/ sub /)과 성형성, 소결성 및 기계적 특성을 비교하여 분석한 결과 본 연구방법에 의해 제조된 것이 성형성이 우수하고, 소결치수의 변화가 거의 없었으며, 같은 소결밀도 및 소경온도 조건에서 인장강도는 $15~20Kg/\textrm{mm}^2$, 경도는 Hv20-30 더 크고, 열처리 하였을 때도 경도 및 인장강도가 좀 더 양호한 결과를 얻었다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1994년도 춘계학술대회강연 및 발표대회 강연및 발표논문 초록집
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• pp.40-41
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• 1994

• Journal of Advanced Marine Engineering and Technology
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• 제22권1호
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• pp.67-76
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• 1998

Friction materials for brake linings and clutches have severe performance requirements. The principal function of such frictional elements is to convert kinetic energy to heat, and then either to absorb or to dissipate heat. In order to achieve these objectives, the coefficient of friction must be as high as possible, independent of variations in operating conditions, and the necessary energy conversion must be accomplished with a minimum of wear on the contacting parts. In this study, Al powder, Al bronze powder and Mo powder used in general for automobile brake was sprayed on automobile brake disc to restrain rust and to maintain friction performance. Dynamo and corrosion tests have been carried out. It is concluded that the sprayed disc with Al bronze powder has the most improved frictional performance and anti-corrosive characteristics. The main results obtained can be summarized as follows; 1. From the corrosion current density test for gray cast iron and sprayed disc with powders of Al, Al bronze and Mo, it was cleared that the spray treatment with Al bronze powder showed the most superior anti-corrosive characteristics than other powders. 2. By anode polarization toward the noble direction from corrosion potential, corrosion current density with sprayed brake disc by Al-bronze powder was the lowest. 3. Mean frictional coefficients obtained from dynamo test are as follows : the sprayed disc with Al(99.99%) powder was 0.190 ; the sprayed disc with Al-bronze powder was 0.312 ; the sprayed disc with Mo powder was 0.257 ; the non-sprayed disc of gray cast iron was 0.331. In the case of the sprayed disc Al-bronze powder showed the most excellent frictional characteristics . 4. Amount of burnish quantity obtained from burnish test by dynamometer is as follows : the sprayed disc with Al-powder was 1.079 mm : the sprayed disc with Al-bronze powder was 0.155 mm : the sprayed disc with Mo powder was 0.253 mm : the non-sprayed disc of gray cast iron was 0.241 mm. Al-bronze powder also showed the most excellent burnish characteristics.

• Journal of Magnetics
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• 제16권3호
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• pp.318-321
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• 2011

A new Fe-based amorphous compound powder was prepared from Fe-Si-B amorphous powder by crushing amorphous ribbons as the first magnetic component and Fe-Cr-Mo metallic glassy powder by water atomization as the second magnetic component. Subsequently by adding organic and inorganic binders to the compound powder and cold pressing, the new Fe-based amorphous compound powder cores were fabricated. This new Fe-based amorphous compound powder cores combine the superior DC-Bias properties and the excellent core loss. The core loss of 500 kW/$m^3$ at $B_m$ = 0.1T and f = 100 kHz was obtained When the mass ratio of FeSiB/FeCrMo equals 3:2, and meanwhile the DC-bias properties of the new Fe-based amorphous compound powder cores just decreased by 10% compared with that of the FeSiB powder cores. In addition, with the increasing of the content of the FeCrMo metallic glassy powder, the core loss tends to decrease.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.134-135
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• 2006

Ancorsteel 4300, a high performance Cr-Si-Ni-Mo steel, was unveiled two years ago as the first in a series of powder metallurgy alloys that will simulate wrought steel compositions. Advantages of this alloy include good compressibility, high hardenability, and excellent dimensional stability. More important, however, is that this alloy has the ability to be effectively sintered at $1120^{\circ}C$ and maintain oxygen contents below 500 ppm. This unique blend of performance and processing capabilities provides static and dynamic properties that exceed those of conventional powder metallurgy alloys and approach wrought gearing materials. A second Cr-Si-Ni-Mo alloy has now been developed that offers complimentary performance levels at a lower Mo content. This manuscript reviews properties of the two chromium steels with comparisons to traditional sinter-hardened and heat-treated powder metallurgy alloys.

• 대한치과기공학회지
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• 제37권4호
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• pp.235-242
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• 2015

Purpose: The aims of this study are compare with microstructure and mechanical properties of Co-Cr-Mo alloys fabricated by powder metallurgy(P/M) process and casting process respectively. Methods: Microstructure and micro-hardness were tested by SEM and Vickers Hardness Tester. The sintered specimen was produced by furnace-coolling after sintering, however the casting specimen were produced thru air-cooling and water-cooling after the casting. For observation of phase transformation during sintering, DSC analyzing was carried out. Results: Mean pore size of sintered Co-Cr-Mo alloy was $4.32{\mu}m$ and that of casting alloy was $1.63{\mu}m$. Hardness of sintered alloy was lower than water-quenched casting alloy. Conclusion: Proper sintering temperature of Co-Cr-Mo alloy was above $1,200^{\circ}C$ and pore size of casting specimen were finer than sintered specimen, but hardness were similar.

• 한국분말재료학회지
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• 제20권1호
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• pp.7-12
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• 2013

The effect of particle size distribution on green and sintered properties of Fe-Cr-Mo prealloy powder was investigated in this study. For the study, prealloyed Fe-Cr-Mo powders with different particle sizes were mixed as various ratios and cold compacted at various pressure and sintered at $1250^{\circ}C$ for 30 min, $90%N_2+10%H_2$ atmosphere in the continuous sintering furnace. The results shows that the powders with large particle size distribution have high compressibility and low ejection force. However the green strength are much less than those with small particle size distribution. Tensile prperties of the sintered specimes with large particles size also have high strength and elongation.