• 한국분말재료학회지
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• 제28권6호
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• pp.483-490
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• 2021

A new Fe-Cr-Mo-B-C amorphous alloy is designed, which offers high mechanical strength, corrosion resistance as well as high glass-forming ability and its gas-atomized amorphous powder is deposited on an ASTM A213-T91 steel substrate using the high-velocity oxygen fuel (HVOF) process. The hybrid coating layer, consisting of nanocrystalline and amorphous phases, exhibits strong bonding features with the substrate, without revealing significant pore formation. By the coating process, it is possible to obtain a dense structure in which pores are hardly observed not only inside the coating layer but also at the interface between the coating layer and the substrate. The coating layer exhibits good adhesive strength as well as good wear resistance, making it suitable for coating layers for biomass applications.

• 한국분말재료학회지
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• 제30권1호
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• pp.47-52
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• 2023

The purpose of this study is to develop and evaluate amorphous spray-dried microparticles (SDM) containing levosulpiride to increase its solubility. SDM are prepared via solvent evaporation using polyvinylpyrrolidone (PVP) as the water-soluble polymer and Cremophor RH40 as the surfactant. The SDM is prepared by varying the amounts of PVP and Cremophor RH40, and its physicochemical properties, solubility, and dissolution are confirmed. All levosulpiride-loaded SDMs converted the crystalline drug into an amorphous form, significantly improving drug solubility and dissolution compared with the drug alone. SDM consisting of drug/PVP/Cremophor RH40 in a weight ratio of 5:10:3, with increased solubility (720 ± 36 vs. 1822 ± 51 ㎍/mL) and dissolution rate (10.3 ± 2.2 vs. 92.6 ± 6.0%) compared with drug alone, shows potential as a commercial drug for improved oral bioavailability of levosulpiride.

• The Korean Journal of Ceramics
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• 제6권2호
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• pp.155-158
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• 2000

NMR study has been used for measuring precise quantity of the amorphous phase in the $Si_3N_4$powder. Care must be taken to allow the $^{29}$Si nuclear spin system to fully relax between pulses in order to make the signals proportional to the number of nuclei in each phase. $^{29}$Si MAS spectrum was decomposed into the three spectra of $\alpha$-, $\beta$-, and amorphous $Si_3N_4$assuming pseudo-Voigt function. Moreover, the Rietveld analysis of the powder X-ray diffraction data was performed to measure quantity of crystalline phases as $\alpha/\beta$ ratio.

• 한국분말재료학회지
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• 제17권1호
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• pp.7-12
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• 2010

In this work, effect of various process-control agents (PCAs) on the mechanical alloying of amorphous alloy of $Al_{85}Y_8Ni_5Co_2$ has been investigated. The dependence of the particle shape, size and crystallization behavior of the amorphous alloy powders on the type of PCAs and their concentrations was investigated by using X-ray diffraction, field-emission scanning electron microscopy and differential scanning calorimetry. It was found that the additive of toluene could affect positively the amorphization and thermally induced crystallization processes, as well as the size refinement, morphology and particle-size distribution of as-milled powders in comparison with alloy obtained without PCA.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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• pp.424-428
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• 2012

공기흡입형 추진기관은 운용의 단순함, 저비용, 저장의 용이성 등의 장점으로 각광받고 있는 추진 기관이다. 본 논문에서는 Boron을 이용한 공기흡입형 추진기관의 가스발생기에 사용될 추진제 연구를 수행하였다. 이를 위하여, Amorphous Boron Powder를 적용한 추진제에 다양한 첨가제를 사용하여 연소특성을 파악하였고, Boron bead를 제조하여 추진제에 적용하여 Amorphous Boron Power를 적용한 추진제와의 차이점을 비교 분석 하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.680.1-680.1
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• 2006

• 한국세라믹학회지
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• 제26권1호
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• pp.81-90
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• 1989

High purity alumina and amorphous silica were prepared from Ha-dong kaolin by means of appliance of sulfuric acid. The effect of sulfuric acid concentration, reaction temperature and reaction time on the formation of aluminum sulfate was investigated. The precipitation conditions ofaluminum sulfate from the sulfuric acid solution with ethanol and ammonium hydroxide were deteremined. In the optimum condition, the conversion of aluminum oxide in kaolin to aluminum oxide powder was 85.0 percent. Alumina powder was prepared by calcination of the precipitates, and its purity was 99.0 percent.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.990-991
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• 2006

• 한국재료학회지
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• 제21권2호
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• pp.106-110
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• 2011

A high thermal conductive AlN composite coating is attractive in thermal management applications. In this study, AlN-YAG composite coatings were manufactured by atmospheric plasma spraying from two different powders: spray-dried and plasma-treated. The mixture of both AlN and YAG was first mechanically alloyed and then spray-dried to obtain an agglomerated powder. The spray-dried powder was primarily spherical in shape and composed of an agglomerate of primary particles. The decomposition of AlN was pronounced at elevated temperatures due to the porous nature of the spray-dried powder, and was completely eliminated in nitrogen environment. A highly spherical, dense AlN-YAG composite powder was synthesized by plasma alloying and spheroidization (PAS) in an inert gas environment. The AlN-YAG coatings consisted of irregular-shaped, crystalline AlN particles embedded in amorphous YAG phase, indicating solid deposition of AlN and liquid deposition of YAG. The PAS-processed powder produced a lower-porosity and higher-hardness AlN-YAG coating due to a greater degree of melting in the plasma jet, compared to that of the spray-dried powder. The amorphization of the YAG matrix was evidence of melting degree of feedstock powder in flight because a fully molten YAG droplet formed an amorphous phase during splat quenching.

• 한국분말재료학회지
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• 제30권1호
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• pp.41-46
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• 2023

In this study, an Al₈₂Ni₇Co₃Y₈ (at%) bulk metallic glass is fabricated using gas-atomized Al₈₂Ni₇Co₃Y₈ metallic glass powder and subsequent spark plasma sintering (SPS). The effect of powder size on the consolidation of bulk metallic glass is considered by dividing it into 5 ㎛ or less and 20-45 ㎛. The sintered Al₈₂Ni₇Co₃Y₈ bulk metallic glasses exhibit crystallization behavior and crystallization enthalpy similar to those of the Al₈₂Ni₇Co₃Y₈ powder with 5 ㎛ or less and it is confirmed that no crystallization occurred during the sintering process. From these results, we conclude that the Z-position-controlled spark plasma sintering process, using superplastic deformation by viscous flow in the supercooled liquid-phase region of amorphous powder, is an effective process for manufacturing bulk metallic glass.