• Corrosion Science and Technology
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• v.9 no.6
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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.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.11
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• pp.727-730
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• 2015

In this paper, we fabricated organic compounds detector using the MWCNT/PMMA (multi-walled carbon nanotube / polymethylmethacrylate) composite film. We used polymer film as a matrix material for the device framework, and introduced CNTs for reacting with the organic compounds resulting in changing electrical conductivity. Spray coating method was used to form the MWCNT/PMMA composite film detector, and pattern formation of the detector was done by shadow mask during the spray coating process. We investigated changes of electrical conductivity of the detector before and after the organic compounds exposure. Electrical conductivity of the detector tended to decrease after the exposure with various organic compounds such as acetone, tetrahydrofuran (THF), toluene, and dimethylformamide (DMF). Finally we conclude that organic compounds detection by the MWCNT/PMMA composite film detector was possible, and expect the feasibility of commercial MWCNT/PMMA composite film detector for various organic compounds.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.67-72
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• 1998

Due to excellent corrosion resistance, in particular against sea water, Al-2wt.$\%$Zn alloys have been used as the sacrifice anode material for tube of the ORV. Al-2wt.$\%$Zn alloys thermal-sprayed coating, however, were spalled on the lower part of ORV due to the lack of bonding strength between base material and coating layer and the dropping energy of sea water, To overcome the problems of the thermal spray coating, we developed the cladded tube manufacturing process by coextrusion of the clad and base metal. The corrosion resistance of cladded tube was improved by two times at least, compared with that of the present thermal spray coated vaporizer tubes.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.104-105
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• 2013

The buildings constructed with steel structure is coated with certified fire resistive material to resist from fire. Coating materials lose their initial performances as time passes, so they need some maintenance. Fireproof spray-application also loses its performance and this performance loss of thr fireproof spray-application is very important because fire resistance of buildings depends on fireproof spray-application. So this study is to develop Acceleration durability test method of Fireproof spray-application, and use the Certification of fire resistant coating system.

• Korean Journal of Metals and Materials
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• v.47 no.1
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• pp.13-20
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• 2009

This work presents functionally graded coatings (FGC) of hydroxyapatite (HA) and metallic powders on Ti-6Al-4V implants using plasma spray coating method. HA has been the most frequently used coating material due to its excellent compatibility with human bones. However, because of the abrupt changes in thermomechanical properties between HA and the metallic implant across an interface, and residual stress induced on cooling from coating temperture to room temperature, debonding at the interface occurs in use sometimes. In this work, FGC of HA and Ti or Ti-alloy powders is made to mitigate the abrupt property changes at the interface and the effect of FGC on residual stress release is investigated by evaluating the mechanical bond strength between the implant and the HA coating layers. Thermal annealing is done after coating in order to crystallize the HA coating layer which tends to have amorphous structure during thermal spray coating. The effects of types and compositional ratio of metallic powders in FGC and annealing conditions on the bond strength are also evaluated by strength tests and the microstructure analysis of coating layers and interfaces. Finally, biocompatibility of the coating layers are tested under ISO 10993-5.

• Journal of Powder Materials
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• v.23 no.1
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• pp.15-20
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• 2016

Niobium is one of the most important and rarest metals, and is used in the electronic and energy industries. However, it's extremely high melting point and oxygen affinity limits the manufacture of Nb coating materials. Here, a Nb coating material is manufactured using a kinetic spray process followed by hot isotactic pressing to improve its properties. OM (optical microscope), XRD (X-ray diffraction), SEM (scanning electron microscopy), and Vickers hardness and EPMA (electron probe micro analyzer) tests are employed to investigate the macroscopic properties of the manufactured Nb materials. The powder used to manufacture the material has angular-shaped particles with an average particle size of $23.8{\mu}m$. The porosity and hardness of the manufactured Nb material are 0.18% and 221 Hv, respectively. Additional HIP is applied to the manufactured Nb material for 4 h under an Ar atmosphere after which the porosity decreases to 0.08% and the hardness increases to 253 Hv. Phase analysis after the HIP shows the presence of only pure Nb. The study also discusses the possibility of using the manufactured Nb material as a sputtering target.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.512-519
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• 2001

Sink roll has been used in molten Zn-0.2%Al alloy bath of continuous galvanizing line in sinking and stabilizing process of the steel strip in molten metal bath. In this process, although the scraper scraps off the sink roll surface, the dross compounds is builded up on the sink roll surface and the life time of the sink roll is shorten by the dross compounds. The present study was investigated the application of the spray coating layer on sink roll body for improving durability In molten Zn-0.2%Al alloy. Through the durability tests in molten Zn-0.2%Al alloy with various ceramic and cermet coating layer, the optimum bond and top coating material was obtained. As the results, the system of STS430F base metal, WC-l7Co bond and $ZrO_2-SiO_2$ top coating was clarified to be the best quality of durability in molten Zn-0.2%Al alloy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.7
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• pp.462-466
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• 2015

In this paper, we investigated the relations between dispersion of CNTs (carbon nanotubes) and electrical conductivity in the CNT/PVDF (polyvinylidene fluoride) composite film. By adding hydrophobic CNTs as filler into the PVDF matrix, we fabricated hydrophobic and electrically conducting polymer coating film. Dispersion of CNTs in the CNT/PVDF composite film plays a significant role in terms of electrical conductivity and wetting property. Spray coating method was used to form the CNT/PVDF composite films by injecting the dispersed CNTs in the PVDF solution with different weight ratios from 0.7 wt% to 7 wt%. We investigated the electrical properties and contact angles of the CNT/PVDF composite films with the CNT concentration. Finally we discussed the conducting mechanism and feasibility of the CNT/PVDF composite film for the conducting polymer films.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.420.1-420.1
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• 2016

Colloidal quantum dot (CQD) is emerging as a promising active material for next-generation solar cell applications because of its inexpensive and solution-processable characteristics as well as unique properties such as a tunable band-gap due to the quantum-size effect and multiple exciton generation. However, the most widely used spin-coating method for the formation of the quantum dot (QD) active layers is generally hard to be adopted for high productivity and large-area process. Instead, the spray-coating technique may potentially be utilized for high-throughput production of the CQD solar cells (CQDSCs) because it can be adapted to continuous process and large-area deposition on various substrates although the cell efficiency is still lower than that of the devices fabricated with spin-coating method. In this work, we observed that the subsequent treatment of two different ligands, halide ion and butanedithiol, on the lead sulfide (PbS) QD layer significantly enhanced the cell efficiency of the spray CQDSCs. The maximum power conversion efficiency was 5.3%, comparable to that of the spin-coating CQDSCs.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.245-246
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• 2009

The large and high-speed vessels have been greatly advanced, but ship materials have been caused the problem such as corrosion, cavitation and erosion. Cavitation can produce material damage such as pumps, turbines, valves and ship propellers etc. To solve these problems, the cavitation and electrochemical characteristics for thermal spray coating and the sealing are executed to obtain the excellent corrosion protection characteristics in sea water environment.