• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.680.2-680.2
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• 2006

• Advances in materials Research
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• v.6 no.4
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• pp.343-348
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• 2017

High-pressure gas atomization was employed to prepare the Fe-based $Fe_{50}Cr_{24}Mo_{21}Si_2B_3$ alloy powder. The effect of flow rate of atomizing gas on the median powder diameter was studied. The results show that the powder size decreased with increasing the flow rate of atomizing gas. Fe-based alloy coatings with amorphous phase fraction was then prepared by high velocity oxygen fuel spraying (HVOF) of gas atomized $Fe_{50}Cr_{24}Mo_{21}Si_2B_3$ powder. Microstructural studies show that the coatings present dense layered structure and low porosity of 0.17% in about $200{\mu}m$ thickness. The Fe-based alloy coating exhibits an average hardness of about 1230 HV. Our results show that the HVOF process results in dense and well-bonded coatings, making it attractive for protective coatings applications.

• Journal of Welding and Joining
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• v.14 no.3
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• pp.66-74
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• 1996

In this study, friction and wear properties of flame sprayed specimens and hard Cr plating specimens were tested, and their properties were compared each other in dry and lubrication condition. Ni-Cr powder and steel powder were used as the spray powder and sprayed on the steel(S45C) substrate by flame sprayed method. Each wear surface was observed with SEM after friction and wear test. The friction coefficient of the as-forged steel specimens was the highest among surface treatment specimens, and the other specimens appeared in order as follows ; hard Cr-plating specimens, Ni-Cr powder sprayed specimens, steel powder sprayed specimens. Comparing the wear volumes in dry condition, as forged steel specimens appeared the greatest wear volume, and the other specimens appeared wear volume in order as follows ; Ni-Cr powder sprayed specimens, steel powder sprayed specimens, hard Cr plating specimens. In friction and wear test, the hard Cr plating specimens were worn by the abrasive phenomenon, involving the cracks. The wear volume of steel powder sprayed specimens was lower than that of Ni-Cr powder sprayed specimens. Comparing the tensile strength of both sprayed coating layers, the steel powder sprayed coating layer was better than Ni-Cr powder sprayed coating layer.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.240-242
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• 2000

This study was investigated absorption properties of electromagnetic wave in thermal sprayed Sr-ferrite coatings. The experiment of this study was ; manufactured thermal spraying powder for improving absorption-efficiency, processed for increasing strength of thermal spray coatings, and measured the electromagnetic wave shielding efficiency. This study was obtained excellent absorption-efficiency by thermal sprayed Sr-ferrite coatings.

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.63.2-63
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• 2002

• Magazine of the Korea Concrete Institute
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• v.27 no.5
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• pp.49-51
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• 2015

• Korean Journal of Materials Research
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• v.12 no.10
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• pp.784-790
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• 2002

For mass product of nanocrystalline ZnO ultrafine powders, self-sustaining combustion process(SCP) and ultrasonic spray combustion method(USCM) were applied at the same time. Ultrasonic spray gun was attached on top of the vertical type furnace. The droplet was sprayed into reaction zone of the furnace to form SCP which produces spherical shape with soft agglomerate crystalline ZnO particles. To characterize formed particles, fuel and oxidizing agent for SCP were used glycine and zinc nitrate or zinc hydroxide. Respectively, with changing combustion temperature and mixture ratio of oxidizing agent and fuel, the best ultrasonic spray conditions were obtained. To observe ultrasonic spray effect, two types of powder synthesis processes were compared. One was directly sprayed into furnace from the precursor solution (Type A), the other directly was heated on the hot plate without using spray gun (Type B). Powder obtained by type A was porous sponge shape with heavy agglomeration, but powder obtained using type B was finer primary particle size, spherical shape with weak agglomeration and bigger value of specific surface area. 9/ This can be due to much lower reaction temperature of type B at ignition time than type A. Synthesized nanocrystalline ZnO powders at the best ultrasonic spray conditions have primary particle size in range 20~30nm and specific surface area is about 20m$^2$/g.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.291-301
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• 2017

Objectives: In order to improve the working environment and solve the complaints, many efforts have been made to remove the odor from the industrial process. There are many disposal methods to remove odor, but there are many disadvantages and inadequate applications. The Purpose of this study was to develop a bag-filer system for odor removal using powder adsorbent. Methods: The bag-filter system is composed of a shear bag filter, an absorbent spraying system and an absorbent circulation system. The spraying absorbent system was connected with the inlet duct of the shear bag filter for inputting adsorbent. And the absorbent circulation system can transport the collecting adsorbent from hoper to the inlet duct of the system. As a result, the adsorbent can remove odor with recycling in the system. Also affective factors like the powdered absorbent combination and injection method was researched for maximization of system efficiency. The study was conducted in two stages. The first step was testing equipment made and the second is to evaluate the efficiency of the odor control by connecting to the actual odor generation process. Results: Both experiment stages showed efficient odor control ability. The adsorption efficiency of the system is demonstrated and the odor was adsorbed well by the powder adsorbent. It is essential to accurately understand the characteristics of the odorous and use the appropriate adsorbent. Although the powder adsorbent was used in the experiment, the problem of scattering did not occur due to the high degree of system sealing. Also the system manufactured in this study was designed to recycle the adsorbent, so adsorbent reuse or batch processing is convenient. Conclusions: The applicability of the system has been proven through this research. Customized systems for industrial process and the appropriate adsorbent base on the characteristics of pollutant generation will show efficient odor collection ability.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.283-288
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• 2006

Trichoderma harzianum YC459 (Th 459), isolated from sawdust compost, was effective in controlling cucumber and tomato gray mold caused by Botrytis cinerea under controlled and plastic film tunnel conditions. A water suspension of the wettable powder formulation of Th 459 significantly $(P\leq0.05)$ reduced the severity of cucumber gray mold by foliar spraying at all tested concentrations from $10^5\;to\;10^8$ colony forming unit (cfu)/ml in repeated experiments. The control efficacy was maintained at least seven days with the average control value of 70% in cucumber pot tests. Mixing one to eight grams of the granular formulation ($10^8cfu/g$ dry weight) of Th 459 into one liter nursery potting mix at seeding also significantly $(P\leq0.05)$ reduced the severity of cucumber gray mold by suppression of lesion formation three weeks after treatment. Application of mixing granular formulation at seeding in combination with foliar spraying during cultivation provided a more significant reduction $(P\leq0.05)$ of cucumber gray mold than granule mixing or leaf spray alone. The foliar spraying of the formulated wettable powder of Th 459 significantly $(P\leq0.05)$ reduced the infection of tomato fruits by B. cinerea as effective as the chemical fungicide, dichlofluanid, in three plastic film tunnel experiment trials. It is suggested that effective control of gray mold of cucumber and tomato can be provided by both treatment of Th 459 into potting mix and foliar spray through induction of systemic resistance and direct inhibition of the pathogen.

• Journal of Powder Materials
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• v.16 no.3
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• pp.185-190
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• 2009

Fe-Cr steels are the most promising candidate for interconnect in solid oxide fuel cells. In this study, an effective, dense and well adherent (LaSr)(CrCo)$O_3$ [LSCC] coating layer was produced onto 430 stainless steel (STS-430) by atmospheric plasma spraying and the oxidation behavior as well as electrical properties of the LSCC coated STS-430 were investigated. A significant oxidation of pristine STS-430 occurred at $800^{\circ}C$ in air environment, leading to the formation of $Cr_2O_3$ and $FeCr_2O_4$ scale layer up to ${\sim}7{\mu}m$ after 1200h, and consequently increased an area specific resistance of $330\;m{\Omega}{\cdot}cm^2$. Although the plasma sprayed LSCC coating contained the characteristic pore network, the coated samples presented apparent advantages in reducing oxidation growth of STS-430, resulting a decrease in oxide scale thickness of ${\sim}1{\mu}m$ at $800^{\circ}C$ after 1200h. The area specific resistance of the LSCC coated STS-430 was much reduced to ${\sim}7\;m{\Omega}{\cdot}cm^2$ after exposure at $800^{\circ}C$ for 1200h, compared to that of the pristine STS-403.