• Corrosion Science and Technology
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• 제9권6호
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• pp.317-324
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• 2010

Marine transportation by ships is characterized by remote, large-volume and lower rates than the others carry system. Ships account for over 80% of all international trading, and marine transportation is an internationally competitive, strategic, and great national important industry. The construction of larger and faster ships has brought about many problems such as cavitations and erosion corrosion. Cavitations and erosion corrosion make damages on materials and leads to break down members due to continuous physical contacts with shock waves and fluids from the generation and extinction of air bubbles in sea water vortex. The steel used for ship constructions was spray-coated with Al wire, and additionally sealed with fluorine silicone sealing material. Results of experiment, corrosion resistance of sealed thermal spray coating was improved, however in cavitation resistance, the large effect was not appeared. Accordingly, this study applied for thermal spray coating to provide better electrochemical characteristics and corrosion resistance in marine environment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.291-291
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• 2010

Organic solar cells have attracted much interest due to the potential advantage of the lightness, simple solution processing and flexibility. Until recently, the focus of organic solar cells research has been on optimization of material processing to improve the power conversion efficiency. However, area scaling is an important position for alternative to the market dominating solar cells. Spray deposition technologies have advantage of less material wastage and possibility of large scale photoactive area coating when compared with spin coating process. We investigated the performance of organic solar cells as a function of active area using two types of deposition process. The commonly used process is spin coating which can be fabricated organic materials deposition for devices. Spray deposition process compare with spin coating for large-area organic solar cells. The spray deposition organic layer shows excellent performance up to the active area of $4\;cm^2$ with the PCE of ~3.0 % under AM.1.5 simulated illumination with an intensity of $100mW/cm^2$. This indicates that the spray deposition process can be used as a mass production process for evaluating large-area organic solar cells.

• 설비공학논문집
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• 제18권4호
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• pp.304-311
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• 2006

Experiments on evaporative spray cooling on the square plate heaters with plain or micro-porous coated surfaces were performed in this study. Micro-porous coated surfaces were made by using DOM [Diamond particle, Omegabond 101, Methyl-Ethyl-Keton] method. In case of purely air-jet cooling, the micro-porous coating doesn't affect the cooling capacity. In spray cooling three different flow patterns (complete wetting, evaporative wetting, dryout) are observed on both plain and micro-porous coated surfaces. The effects of various operating conditions, such as water flow rate, particle size, and coating thickness were investigated on the micro-porous coated surfaces. It is found that the level of surface wetting is an important factor to determine the performance of spray cooling. It depends on the balance between absorbed liquid amount by capillary force over porosity and the evaporative amount. The micro-porous coated surface has largest cooling capacity, especially in the evaporative wetting zone. It is found that the effects of liquid flow rate and coating thickness are significant in evaporative wetting zone, but are not in complete wetting and dryout zones.

• Corrosion Science and Technology
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• 제21권1호
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• pp.68-76
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• 2022

Several technologies are employed to protect substrates from corrosion and erosion damage. In particular, arc thermal spray coating technology is widely used as anti-corrosive technology for steel and concrete structures and is applied to offshore plants and petrochemical and drilling facilities. In this investigation, solid particle impingement erosion experiments were performed on an arc thermal spraying-coated specimen using 85% Al-14% Zn-1% Zr wire rod in KR-RA steel. This study investigated the effect of fluorosilicone sealing on the erosion resistance characteristics of the thermal spray coating layer. The erosion rates of the thermal spray-coated and sealed specimens were 4.1×10^-4 and 8.5×10^-4, respectively. At the beginning of the experiment, the fluorosilicone sealant was almost destroyed by the impact of the solid particles. The destruction time for the coating layer was 10 minutes for the thermal spray-coated specimen and 13 minutes for the sealed specimens, indicating that the sealed specimens had better erosion resistance characteristics to solid particle impingement.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.157.2-157.2
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• 2016

Water repellent surfaces may enhance the condensation by efficiently removing the condensed droplets. However, such surfaces may lose their original performance as they are exposed to external mechanical stresses. In this work, we fabricated spray-coated mechanically robust superhydrophobic surfaces using treated titanium dioxide (Type 1) or silica particles (Type 2). Then we compared the mechanical robustness of such surfaces with the silane-coated superhydrophobic surface and PEEK coated surface using a controlled-sand blasting method. The results show that the spray-coated samples can maintain the same level of the contact angle hysteresis than silane-coated superhydorphobic surface after sand blasting at 2 bar. The spray-coating method was applied to the tube type condenser and the condensation behaviors were observed within the environmental chamber with controlled pressure, humidity and non-condensable gas. Previously-reported droplet jumping was observed in the early stage of the condensation event, but soon the droplet jumping stopped and only dropwise condensation was observed since the condensed droplets were pinned on the cracks at spray-coated surfaces. The static contact angle decreases from $158.0^{\circ}$ to $133.2^{\circ}$, and hysteresis increases from $3.0^{\circ}$ to $23.5^{\circ}$ when active condensation occurs on such surfaces. This work suggests the benefits and limitation of spray-coated superhydrophobic condensers and help develop advanced condensers for practical use.

• 대한조선학회논문집
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• 제47권5호
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• pp.743-749
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• 2010

Multi-nozzle spray painting procedure of the inorganic zinc shop primer was established in order to obtain uniform film thickness. The shop primer paint prevents the corrosion of steel block during shipbuilding. When the dry film thickness of shop primer is insufficient, rust will be generated on the steel block. Otherwise, thick coating of shop primer may be a problem of weld defect. So, it is important to obtain the uniform film thickness of shop primer. The uniformity of dry film thickness is affected by spray speed, distance from spray gun to target surface and overlapping span of spray path. In order to uniformly maintain coating thickness of shop primer, the coating procedure was established based on the correlation of shop primer spray variables.

• Journal of Welding and Joining
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• 제26권6호
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• pp.74-80
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• 2008

A finite element modeling approach has been described for the simulation and analysis of the micron-scaled solid particle impact behavior in kinetic spraying process, using an explicit code (ABAQUS 6.7-2). High-strain-rate plastic deformation and interface bonding features of the copper, nickel, aluminum, and titanium were investigated via FEM in conjunction with the Johnson-Cook plasticity model. Different aspects of adiabatic shear instabilities of the materials were characterized as a concept of thermal boost-up zone (TBZ), and also discussed based upon energy balance concept with respect to relative recovery energy (RRE) for the purpose of optimizing the bonding process.

• 전기학회논문지
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• 제60권1호
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• pp.85-92
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• 2011

Main characteristic in railroad is the guided movement of the wheel by the track through a metal-to-metal contact, conferring to the rail vehicle a single degree of freedom. There are defects such as head check, shelling, corrugation, squats etc in surface of the rail by interface between the wheel and rail. These defects bring about reducing the life-cycle of rails and track components and increasing noises. In case of bad conditions, it is possible to happen to full-scale accident such as derailment. Recently, the track capacity has been increased for increasing speed and operation efficiency. So, maintenance and indirect cost have been increased. Currently, a coating method of rail construction is proposed by using the ceramics in Korea. Rails are used as the earth in electrical railroad systems. Currently traction return current is flowed through wheels of trains. In case of rails coated, problems are caused in the contact power between wheel and coating material of spray. In this paper, electric model is presented in the AT feeding method. In case of rails coated, electric model is presented. Also, standard resistance of the ceramic is demonstrated by contact power between wheel and coating material of spray.

• 한국재료학회지
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• 제24권7호
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• pp.357-362
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• 2014

Thermal barrier coatings(TBCs) are being applied in many industrial fields such as thermal power generation, aviation and seasonal fields. $ZrO_2-Y_2O_3$(8%) thermal spray coating powders are commercially used as thermal-barrier coating materials to protect against oxidation and corrosion of heat-resistant alloys at elevated temperatures. Currently, $ZrO_2-Y_2O_3$(8%) thermal-spray powder is made using the industrial co-precipitation process, which is very complex and requires a lot of time. In this study, orthorhombic $ZrO_2$ and $Y_2O_3$ powders were fabricated by mechanical mixing, which is more economical than the co-precipitation process. A tetragonal, yttria-stabilized zirconia(YSZ) coating-layer was produced by plasma spraying, using orthorhombic $ZrO_2-Y_2O_3$(8%) powder. Our experimental results indicate that $ZrO_2-Y_2O_3$(8%) mixed powder can be used economically in industry because it is no longer necessary to make this powder by liquid and gas-phase methods.

• 한국재료학회지
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• 제25권9호
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• pp.442-449
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• 2015

The effects of coating parameters were investigated in wear resistance coatings of Diamalloy-406 on Inconel 718 to obtain an optimum coating condition by high velocity oxy-fuel spraying. The coating parameters, the flow rates of source gases (hydrogen and oxygen), the powder feed rate, and the spray distance, were designed by the Taguchi method. The optimal conditions were determined: oxygen flow rate 34 FRM, hydrogen flow rate 57 FRM, powder feed rate 35 g/min, and spray distance 7 inch. Friction coefficients of the coating and the substrate decreased with an increasing sliding surface temperature from $25^{\circ}C$ to $450^{\circ}C$. The friction coefficient of Diamalloy-4006 coating decreased as the sliding surface temperature increased from $0.43{\pm}0.01$ at $25^{\circ}C$ to $0.29{\pm}0.01$ at $450^{\circ}C$. The wear trace and wear depth of the coating were smaller than the substrate at all temperatures tested. The relationship between spray parameters and wear resistance was discussed extensively, based on the measured roughness, hardness, and porosity in each coating.