• International Journal of Concrete Structures and Materials
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• v.8 no.3
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• pp.185-199
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• 2014

As the national transportation infrastructure ages and deteriorates, many existing bridges require frequent and costly maintenance and repairs. The objective of this work was to synthesize new and existing types of beam end coatings and treatments that have been proven to extend the life of new and existing concrete and steel bridge beams. A comprehensive literature review, along with online surveys and phone interviews of State department of transportations (DOTs) and coating manufacturers was conducted to gather information about existing and recently developed technologies. The study revealed that while many promising coatings and treatments are offered on the market, there is a lack of readily available laboratory results that would enable direct comparison of the available methods. This finding applies in terms of the coatings' durability and the potential for extending the service life of existing bridges. Most of the interviewed State DOTs' personnel assessed the products listed in respective DOT's Qualified Products Lists as performing 'well'. However, there was significant variability between states in the type of the products used. Among the agencies contacted, none was able to suggest the most promising or advanced products, either for concrete or steel bridge beam end treatments. This suggests that comprehensive laboratory evaluation would be necessary for selecting the best available beam end treatments and coatings.

• Korean Journal of Materials Research
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• v.16 no.7
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• pp.430-434
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• 2006

Au/Ni coatings are widely used in the electrical interconnect system, such as connectors, sockets and wire crimps. But due to repeated mechanical contacts, fretting corrosion occurs and causes a rapid increase in resistance. As an attempt to resolve these problem, application of Ni-P-PTFE to replace Ni undercoats was proposed, for which basic materials properties of Ni-P-PTFE coatings for preventing fretting corrosion was examined in this study. The Ni-P-PTFE coatings were formed by electroless Ni plating and PTFE coating followed by the heat-treatment. PTFE particles were found to be uniformly distributed in the Ni-P matrix. The Ni-P-PTFE coatings showed the excellent anti-adherent property with the contact angle of $104.3^{\circ}$, microhardness of 144.3 Hv comparable to that of Ni-P, and electric conductivity equivalent to that of Ni-P.

• Tribology and Lubricants
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• v.35 no.2
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• pp.106-113
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• 2019

We investigated the application of tetrahedral amorphous carbon (ta-C) coatings to fabricate a glass lens manufactured using a glass molding process (GMP). In this work, ta-C coatings with different thickness (50, 100, 150 and 200 nm) were deposited on a tungsten carbide (WC-Co) mold using the X-bend filter of a filtered cathode vacuum arc. The effects of thickness on mechanical and tribological properties of the coating were studied. These ta-C coatings were characterized by atomic force microscopy, scanning electron microscopy, nano-indentation measurements, Raman spectrometry, Rockwell-C tests, scratch tests and ball on disc tribometer tests. The nano-indentation measurements showed that hardness increased with an increase in coating thickness. In addition, the G-peak position in the Raman spectra analysis was right shifted from 1520 to $1586cm^{-1}$, indicating that the $sp^3$ content increased with increasing thickness of ta-C coatings. The scratch test showed that, compared to other coatings, the 100-nm-thick ta-C coating displayed excellent adhesion strength without delamination. The friction test was carried out in a nitrogen environment using a ball-on-disk tribometer. The 100-nm-thick ta-C coating showed a low friction coefficient of 0.078. When this coating was applied to a GMP, the life time, i.e., shot counts, dramatically increased up to 2,500 counts, in comparison with Ir-Re coating.

• Korean Journal of Materials Research
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• v.15 no.10
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• pp.621-625
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• 2005

Effects of rf power, pressure, sputtering gas composition, and substrate temperature on the deposition rate of the $WC_x$ coatings were investigated. The effects of rf power and sputtering gas composition on the hardness and corrosion resistance of the $WC_x$ coatings deposited by reactive sputtering were also investigated. X-ray diffraction (XRD) and Auger electron spectroscopy (AES) analyses were performed to determine the structures and compositions of the films, respectively. The hardnesses of the films were investigated using a nanoindenter, scanning electron microscopy, ana a salt-spray test, respectively. The deposition rate of the films was proportional to rf power and inversely proportional to the $CH_4$ content of $Ar/CH_4$ sputtering gas. The deposition rate linearly increased with increasing chamber pressure. The hardness of the $WC_x$ coatings Increased as rf power increased. The highest hardness was obtained at a $Ar/CH_4$ concentration of $10 vol.\%$ in the sputtering gas. The hardness of the $WC_x$ film deposited under optimal conditions was found to be much higher than that of the electroplated chromium film, although the corrosion resistance of the former was slightly lower than that of the latter.

• 한국전기화학회:학술대회논문집
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• 2001.10a
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• pp.19-19
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• 2001

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.53-53
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• 2007

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.218-218
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• 2009

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2002.05a
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• pp.7-8
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• 2002

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.230-230
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• 2009

• Journal of Powder Materials
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• v.14 no.6
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• pp.372-379
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• 2007

The microstructure, mechanical and electrochemical properties of plasma electrolytic coatings (PEO) coatings on Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn-2.0 wt%Y alloys prepared by gas atomization, followed by compaction at 320 for 10 min under the pressure of 700 MPa and sintering at 380 and 420 respectively for 24 h, were investigated, which was compared with the cast Mg-1.0 wt%Zn alloy. All coatings consisting of MgO and $Mg_2SiO_4$ oxides showed porous and coarse surface features with some volcano top-like pores distributed disorderly and cracks between pores. In particular, the surface of coatings on Mg-1.0 wt%Zn-2.0 wt%Y alloy showed smaller area of pores and cracks compared to the Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn alloys. The cross section micro-hardness of coatings on the gas atomized Mg-Zn-Y alloys was higher than that on the cast Mg-1.0 wt%Zn alloy. Additionally, the coated Mg-1.0 wt%Zn-2.0 wt%Y alloy exhibited the best corrosion resistance in 3.5%NaCl solution. It could be concluded that the addition of Y has a beneficial effect on the formation of protective and hard coatings on Mg alloys by plasma electrolytic oxidation treatment.