• Title/Summary/Keyword: spraying thickness

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A Study on the Process for Improving Mechanical Property of Sand Casting by Using the Binder Jetting Method (사형 주조에서 바인더 젯 3D 프린터를 이용한 기계적 물성 향상을 위한 공정 연구)

  • Jung-Chul Hwang;Tae-Sung Kim
    • Journal of the Korea Safety Management & Science
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    • v.25 no.1
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    • pp.23-29
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    • 2023
  • Among the Additive Manufacturing (AM) technologies, the Binder-Jetting printing technology is a method of spraying an adhesive on the surface of powder and laminate layer by layer. Recently, this technique has become a major issue in the production of large casting products such as ship-building, custom vehicles and so on. In this study, we performed research to make actual mold castings and increase mechanical property by using special sand and water-based binders. For use as a mold, it has a strength of more than 3MPa and permeability. Various experiments were carried out to obtain suitable them. The major process parameters were binder jetting volume, binder types, layer thickness and heat treatment condition. As a result of this study, the binder drop quantity was measured to be about 60 pico-liter, layer thickness was 100㎛ and the heat treatment condition was measured about 1,000℃ and compressive strength were measured to be more than 5MPa. The optimum condition of this experiment was established through actual casting of aluminum. The equipment used in this study was a Freeforms T400 model (SFS Co., Ltd.), and the printing area of 420 * 300 * 250mm and resolution of 600dpi can be realized.

An Electrochemical Evaluation of the Corrosion Properties of the Steel with the Type and the Thickness of Metallizing Coatings (금속용사 코팅제의 종류 및 두께에 따른 강재 내식성의 전기화학적 평가)

  • Kang, Myeong-Sik;Eom, Sung-Hyun;Cho, Yeon-Chul;Ahn, Jae-Woo;Kim, Seong-Soo;Lee, Jeong-Bae
    • Resources Recycling
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    • v.25 no.3
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    • pp.55-62
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    • 2016
  • Steel structures exposed to extremely corrosive environment like marine environments and industrial area are generally manufactured by applying various protection treatment to increase their lifetime. Metal spraying is one of the protection methods to overcome some drawbacks of the widely employed technologies. Therefore, lots of research needs to be done to improve the corrosion resistance of steel structures. In this study, the corrosion resistance of steel structures was evaluated with the variation in the type and thickness of metal spray by measuring the corrosion potential and current density. As a raw material for spraying, Zn, Al and their mixture were employed to obtain coating thickness of $30{\sim}100{\mu}m$. Our data indicated that the pure zinc coating with $100{\mu}m$ showed the lowest corrosion potential. In the case of pure Al and Zn 85%-Al 15%, the corrosion potential and current density was decreased compared to pure zinc. It was found that the corrosion potential was decreased with the increase of coating thickness irrespective of the type of the coating.

Numerical Simulation of an Impinging Jet with Various Nozzle-to-strip Distances in the Air-knife System

  • So, Hong-Yun;Yoon, Hyun-Gi;Chung, Myung-Kyoon
    • Corrosion Science and Technology
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    • v.9 no.6
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    • pp.239-246
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    • 2010
  • When galvanized steel strip is produced through a continuous hot-dip galvanizing process, the thickness of the adhered zinc film is controlled by impinging a thin plane nitrogen gas jet. The thickness of the zinc film is generally affected by impinging pressure distribution, its gradient and shearing stress at the steel strip. These factors are influenced by static pressure of gas spraying at air knife nozzle, a nozzle-to-strip distance and strip and a geometric shape of the air knife, as well. At industries, galvanized steel strip is produced by changing static pressure of gas and a distance between the air knife nozzle and strip based on experimental values but remaining a geometric shape of nozzle. Splashing and check-mark strain can generally occur when a distance between the air knife nozzle and strip is too short, while ability of zinc removal can lower due to pressure loss of impinging jet when a distance between the air knife nozzle and strip is too long. In present study, buckling of the jet and change of static pressure are observed by analyzing flow characteristics of the impinging jet. The distance from the nozzle exit to the strip varies from 6 mm to 16 mm by an increment of 2 mm. Moreover, final coating thickness with change of a distance between the air knife nozzle and strip is compared with each case. An ability of zinc removal with the various distances is predicted by numerically calculating the final coating thickness.

An Experimental Study on the Evaluation of EMP Shielding Performance of Concrete Applied with ATMSM Using Zn-Al Alloy Wire (Zn-Al 합금 선재를 이용한 금속용사 공법 적용 콘크리트의 전자파 차폐 성능 평가에 관한 실험적 연구)

  • Choi, Hyun-Jun;Park, Jin-Ho;Min, Tae-Beom;Jang, Hyun-O;Lee, Han-Seung
    • Journal of the Korea Institute of Building Construction
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    • v.19 no.3
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    • pp.209-217
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    • 2019
  • EMP (Electromagnetic Pulse) usually means High Power Electromagnetic Wave (HPEM). In the case of the shielding plate against the EMP, there is a possibility of deterioration of the electromagnetic wave shielding performance due to the skill of the constructor, bad construction, deformation of the shielding plate at the connection portion (joint portion). The inefficient use of space due to the separation distance is also pointed out as a problem. Therefore, this study aims to derive the optimum electromagnetic shielding condition by applying ATMSM to concrete as a part of securing electromagnetic wave shielding performance with reflection loss against concrete wall. Experimental parameters included concrete wall thickness and application of Zn-Al ATMSM. For the concrete wall, the wall thickness was 100 to 300mm, which is generally applied, and experimental parameters were set for the application of Zn-Al metal spraying method to evaluate electromagnetic shielding performance. Experimental results showed that as the thickness increases, the electromagnetic shielding performance increases due to the increase of absorption loss. In addition, after the application of Zn-Al ATMSM, the average shielding performance increased by 56.68 dB on average, which is considered to be increased by the reflection loss of the ATMSM. In addition, it is considered that the shielding performance will be better than that when the conductive mixed material and the ATMSM are simultaneously applied.

A Study on the high temperature oxidation behavior of zirconia plasma coatings on Haselloy X (Zirconala 용사된 Hastelloy X의 고온산화거동)

  • 김재철;신억균;박영규;최시경;김길무
    • Journal of the Korean institute of surface engineering
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    • v.30 no.4
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    • pp.285-297
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    • 1997
  • Finned segment, with which are lined inner wall of the turbine combustors, are subject to severe degradation when they are exposed to a hostile environmment at elevated temperature. To protect the finned segment from this environment and to maintain good mechanical properties of components at high temperature, they are preferred to be coated. The most governing factor for the durability of coatings used in the high temperature is the microstructure of coatings; these are splat from, distibution of microcacks, size and distribution of pores, thickness of coating layer, adhesion between coating layer, and oxidation of band coating. In this study, based on the evaluation of the imported finned segment, new finned segment segment was manufactured with optimum plasma spraying parameters, and their properties were examined. Using $ZrO_2(8wt$Y_2O_3)$,/TEX> powder for ceramic coating and 67Ni-22Cr-10Al-0.5Y mixing powder for bond coating, thickness of ceramic and bond coating layer were varied in order to find optimum condition, the results showed that B2T4(bond coating : 100~250$\mu\textrm{m}$, ceramic coating : 250~300$\mu\textrm{m}$) was the best among the specimens tested. Compared to the imported finned segment, B2T4 has better bond strength, hardness, and isothermal and cyclic oxidation resistance.

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A Study on the Mechanical Properties and Residual Stresses of the Thermally Sprayed Alumina Ceramic Coating Layer (알루미나 세라믹(Alumina Ceramic) 코팅층의 기술적인 특성과 잔류응력의 해소에 관한 연구)

  • 김영식
    • Journal of Ocean Engineering and Technology
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    • v.10 no.2
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    • pp.88-97
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    • 1996
  • The pupose of this study is to improve the mechanical properies and to evaluate the residual stresses of flame-sprayed Alumina ceramic coating layer. The first work in this study is to investigate the effects of strengthening heat treatments on the mechanical properties of coating layer. Strengthening heat treatments for sprayed specimens were carried out in vaccum furnace. The mechanical properties such as microhardness, thermal shock resistance, adhesive strength and erosion resistance were tested for the sprayed specimens after strengthening heat treatments. And it was clear that the mechanical properties of coating layer were much improved by strengthening heat treatments. The second work in this study is to evalute the residual stresses in coating lsyer by numerical analysis. FDM and FEM were used to analyze temperature distribution and residul stresses in coating layer. It was proved that are tensile stresses in coating layer and that residual stresses can be controlled by the appropriate selection of the spraying parameters such as preheat temperature, coating thickness and bond coat thickness.

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Development of Automatic Recognition and Spray Control System for Reducing the Amount of Marine Coating paint (선박용 피도물 도료 사용량 절감을 위한 인식 및 스프레이 자동제어시스템 개발)

  • Jung, Young-Deuk
    • Journal of the Korea Safety Management & Science
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    • v.21 no.3
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    • pp.23-27
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    • 2019
  • The first aim of the study is to improve the productivity by uniformizing the thickness of coating and reducing quality-inspection time. The second aim is to cut down on the raw materials for coating by prevent the waste of spraying in the air during a painting process through a real-time coating-size-recognition monitering to fit the target components. To achieve the two aims, a simplified version of automatic coating control system for recognition of coating for vessels and Spray. With the sytem, following effects are expected: First, quality improvement will be achieved by uniformizing the film-thickness. Second, it will reduce the waste of coating paint by constructing the speed of the coating, the spray gun robot transfer time, and the number of DBs according to the size of the vessel. Third, as a 3D industry, it will be able to solve the difficulty of supply of labors and save up the labor costs. Therefore, in the future, further research will be needed to be applied to various products with DB design that designates the variable value, which is added for each type of pieces by comparing the difference between various types of workpieces and linear ones.

Thermal System Analysis for Optimization of Torch Position in The Core Making Machine. (중자조형기의 토치위치 최적화를 위한 열계해석)

  • 한근조;안성찬;심재준;한동섭
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2000.11a
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    • pp.587-590
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    • 2000
  • The new core making method economized on core sand requested. The new method is heating core box until it reaches reasonable temperature and then spraying core sand with core binder into core box. Inner temperature distribution have to uniform in order to form core of uniform thickness. Therefore, in this study we treat of inner temperature distribution of core box in priority. First, determine proper torch number. Next, optimize the torch position to minimize the average of absolute deviation(AVEDEV) of inner temperature. The results are as followed : 1. The torch number that makes inner temperature distribution about $300^\circ{C}$ uniformly is 25. 2. When $S_H$ and $S_V$ is 0.7, the torch position is optimized and AVEDEV is 5.85.

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Effect of Removal Efficiency of Formaldehyde by Input Coating Concentration of Photocatalyst - with Study of Standardization of Coating Thickness - (광촉매 코팅농도가 포름알데히드 제거능에 미치는 효과 - 코팅 두께 표준화 연구를 중심으로 -)

  • Park Young G.;Han Man-So
    • Journal of environmental and Sanitary engineering
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    • v.20 no.4 s.58
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    • pp.51-58
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    • 2005
  • Photocatalytic degradation using $TiO_2$ Particles suspended in a reactor was experimentally performed to degrade the formaldehyde of indoor pollutants. Exponential increase of degradation appears to prove light availability due to the scattering of W light by particles themselves. Comparative removal studies of formaldehyde were done in both cases of dipping and spraying immobilized techniques of $TiO_2$ Particles suspended in solution. Experiments were performed under several different experimental conditions such as initial concentration of formaldehyde, UV intensity and concentration of photocatalysts. Optimal conditions to degrade formaldehyde were obtained under the conditions of $30\;mg/cm^2$ concentration of catalyst and UV intensity of 30 Watt at the distance of 30 cm using immobilized technique by dipping coating.

Potential for Augmentation of Fruit Quality by Foliar Application of Bacilli Spores on Apple Tree

  • Ryu, Choong-Min;Shin, Jung-Nam;Qi, Wang;Ruhong, Mei;Kim, Eui-Joong;Pan, Jae-Gu
    • The Plant Pathology Journal
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    • v.27 no.2
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    • pp.164-169
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    • 2011
  • Previous studies have addressed the management of phyllosphere pathogens by leaf and root-associated microbes. The present study evaluated the effect of the foliar application of three strains of Bacillus spp. on plant growth and fruit quality. The application of a bacilli spore preparation significantly improved leaf growth parameters such as leaf thickness and photosynthesis capacity, indicating that bacilli treatment directly promoted leaf growth. In addition, foliar treatment resulted in an improvement in the key indicators of fruit quality including water, glucose, and sucrose contents. The present results suggest that foliar spraying of beneficial bacilli is a potential treatment of wide application for the improvement of apple quality. Foliar application of bacilli preparation as effective plant growth-promoting rhizobacteria broadens the spectrum of their availability for orchard application.