• 한국분말재료학회지
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• 제15권5호
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• pp.365-370
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• 2008

In this study, bottom-up powder processing and top-down severe plastic deformation processing approaches were combined in order to achieve both full density and grain refinement with least grain growth. The numerical modeling of the powder process requires the appropriate constitutive model for densification of the powder materials. The present research investigates the effect of representative powder yield function of the Shima-Oyane model and the critical relative density model. It was found that the critical relative density model is better than the Shima-Oyane model for powder densification behavior, especially for initial stage.

• 한국정밀공학회지
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• 제17권8호
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• pp.87-93
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• 2000

Powder Forging technology is being developed rapidly because of its economic merits and the possibility of lightening parts by replacing steel parts with aluminum ones especially in automotive parts manufacturing. Recently Powder Forging process is widely used for manufacturing primary mechanical parts as a combined technology of P/M and precision hot forging. This paper describes the process conditions for the powder forging of Aluminium alloy piston. For example powder alloy design preform design by FEM simulation cold of compaction of specimens and preform sintering of preform powder forging process. The characteristics of sintered compaction of specimens and preform sintering of preform powder forging process. The characteristics of sintered products and final forged piston ones are investigated with tensile strength hardness ductility and so on. Eventually its results prove the improve mechanical properties of the piston produced by powder forging.

• 대한기계학회논문집A
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• 제34권10호
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• pp.1543-1548
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• 2010

분말단조 공정은 정형의 자동차부품을 제작하는데 널리 이용되고 있다. 분말야금이란 금속 원료 분말을 사용하여 원하는 제품의 형태로 성형을 한 다음 적정온도에서 소결하여 필요한 금속 제품을 제조하는 기술을 말한다. 본 연구에서는 자동차 엔진의 경량화를 위한 피스톤 제작에 관한 것이다. 분말단조로 제작 되어진 엔진 피스톤의 특성을 유한요소해석을 통해서 알아보겠다. 유한요소해석은 DEFORM/3D 를 이용해서 성형성을 평가하도록 하겠다. 성형온도, 구배각도, 마찰계수의 변화에 따른 피스톤의 성형성을 알아보겠다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1296-1297
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• 2006

Both plastic and elastic properties change dramatically from the beginning to the end of the compaction phase. Previous investigations have shown that powder transfer and high powder flow during initial compaction at low density affects the strength of the final component significantly. Investigated here are shear failure and elastic shear modulus in the low density range for hard metal powder and for pre-alloyed water atomized iron powder. Direct shear test equipment for sand and clay has been modified to measure the shearing properties of powder for an axial loading between 1 kPa and 500 kPa.

• 동아시아식생활학회지
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• 제23권6호
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• pp.760-767
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• 2013

This study investigated the quality of noodles containing different amounts of collagen powder. Noodles were prepared at ratios of 1, 3, 5 and 7% collagen power based on flour weight. The water binding capacity of the collagen powder was higher than that of flour. The rate of weight increase and volume increase of the noodles as well as the pH and turbidity of the soups were significantly increased with increasing amounts of collagen powder. The noodles showed decreased L and a values, and increased b values with increasing collagen powder in the flour composite. Hardness, springiness and chewiness of cooked noodles increased significantly with the increase in collagen powder content. cohesiveness and brittleness decreased with increasing amounts of added collagen powder. DPPH radical scavenging activity was improved significantly the addition of the collagen powder. Finally sensory evaluation results indicated that the noodles containing 1, 3% collagen powder had higher quality as compared to the other samples. Overall the results suggest that collagen powder is effective for improving the appearance and texture of noodles.

• 한국분말재료학회지
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• 제25권6호
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• pp.482-486
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• 2018

Despite numerous advances in the preparation and use of GaN, and many leading-edge applications in lighting technologies, the preparation of high-quality GaN powder remains a challenge. Ammonolytic preparations of polycrystalline GaN have been studied using various precursors, but all were time-consuming and required high temperatures. In this study, an efficient and low-temperature method to synthesize high-purity hexagonal GaN powder is developed using sub-micron $Ga_2O_3$ powder as a starting material. The sub-micron $Ga_2O_3$ powder was prepared by an ultrasonic spray pyrolysis process. The GaN powder is synthesized from the sub-micron $Ga_2O_3$ powder through a nitridation treatment in an $NH_3$ flow at $800^{\circ}C$. The characteristics of the synthesized powder are systematically examined by X-ray diffraction, scanning and transmission electron microscopy, and UV-vis spectrophotometer.

• Asian-Australasian Journal of Animal Sciences
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• 제25권11호
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• pp.1605-1610
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• 2012

Two experiments were conducted to study the effects of red pepper (Capsicum frutescens) powder or red pepper pigment on the performance and egg yolk color of laying hens. In Exp. 1, 210, thirty-wk old, Hy-line Brown laying hens were fed one of seven diets containing 0.3, 0.6, 1.2, 2.0, 4.8 or 9.6 ppm red pepper pigment or 0.3 ppm carophyll red. Each diet was fed to three replicate batteries of hens with each battery consisting of a row of five cages of hens with two hens per cage (n = 3). In Exp. 2, 180, thirty-wk old, Hyline Brown laying hens, housed similarly to those in Exp. 1, were fed an unsupplemented basal diet as well as treatments in which the basal diet was supplemented with 0.8% red pepper powder processed in a laboratory blender to an average particle size of $300{\mu}m$, 0.8% red pepper powder processed as a super fine powder with a vibrational mill ($44{\mu}m$) and finally 0.8% red pepper powder processed as a super fine powder with a vibrational mill but mixed with 5% $Na_2CO_3$ either before or after grinding. A diet supplemented with 0.3 ppm carophyll red pigment was also included (n = 3). In both experiments, hens were fed the red pepper powder or pigment for 14 days. After feeding of the powder or pigment was terminated, all hens were fed the basal diet for eight more days to determine if the dietary treatments had any residual effects. In Exp. 1, there were no differences in egg-laying performance, feed consumption or feed conversion ratio due to inclusion of red pepper pigment in the diet. Average egg weight was higher (p<0.05) for birds fed 1.2, 2.4 or 9.6 ppm red pepper pigment than for birds fed the diet containing 0.3 ppm red pepper pigment. On d 14, egg color scores increased linearly as the level of red pepper pigment in the diet increased. In Exp. 2, feeding red pepper powder did not affect egg-laying performance, feed consumption or feed conversion ratio (p>0.05). However, compared with the control group, supplementation with all of the red pepper powder treatments increased egg weight (p<0.05). All the red pepper powder treatments also increased (p<0.05) the yolk color score compared with the control. The results of the present study suggest that both red pepper powder and pigment are effective feed additives for improving egg yolk color for laying hens.

• 한국세라믹학회지
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• 제46권5호
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• pp.528-533
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• 2009

High purity $\beta$-SiC powders were synthesized using sol-gel processing. TEOS and phenol resin were used as the starting material for the silicon source and carbon source, respectively. The process turned out to be capable of producing high purity SiC powder purity degree with 99.98 %. However, it was difficult to control the shape and size of $\beta$-SiC powders synthesized by sol-gel process. In this study, $\beta$-SiC powder with size of $1{\sim}5$ um an 30 nm were used as the seeds for $\beta$-SiC to control the $\beta$-SiC powder morphology. It was found that $\beta$-SiC powder seeds was effective to increase the powder average size of synthesized $\beta$-SiC using sol-gel process by acting as the preferred growing sites for $\beta$-SiC.

• 한국분말재료학회지
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• 제30권3호
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• pp.233-241
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• 2023

In this study, we evaluated the effects of acid leaching on the properties of Cr powder synthesized using self-propagating high-temperature synthesis (SHS). Cr powder was synthesized from a mixture of Cr2O3 and magnesium (Mg) powders using the SHS Process, and the byproducts after the reaction were removed using acid leaching. The properties of the recovered Cr powder were analyzed via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), particle size analysis (PSA), and oxygen content analysis. The results show that perfect selective leaching of Cr is challenging because of various factors such as incomplete reaction, reaction kinetics, the presence of impurities, and incompatibility between the acid and metal mixture. Therefore, this study provides essential information on the properties under acidic conditions during the production of high-quality Cr powder using a self-propagating high-temperature synthesis method.

• 한국분말재료학회지
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• 제20권4호
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• pp.280-284
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• 2013

Stress-strain curves are fundamental properties to study characteristics of materials. Flow stress curves of the powder materials are obtained by indirect testing methods, such as tensile test with the bulk materials and powder compaction test, because it is hard to measure the stress-strain curves of the powder materials using conventional uniaxial tensile test due to the limitation of the size and shape of the specimen. Instrumented nanoindentation can measure mechanical properties of very small region from several nanometers to several micrometers, so nanoindentation technique is suitable to obtain the stress-strain curve of the powder materials. In this study, a novel technique to obtain the stress-strain curves using the combination of instrumented nanoindentation and finite element method was introduced and the flow stress curves of Fe powder were measured. Then obtained stress-strain curves were verified by the comparison of the experimental results and the FEA results for powder compaction test.