• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.2053-2065
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• 2003

The current trend in automotive finishing industry is to use more electrostatic rotating bell (ESRB) need space to their higher transfer efficiency. The flow physics related with the transfer efficiency is strongly influenced by operating parameters. In order to improve their high transfer efficiency without compromising the coating quality, a better understanding is necessary to the ESRB application of metallic basecoat painting for the automobile exterior. This paper presents the results from experimental investigation of the ESRB spray to apply water-borne painting. The visualization, the droplet size, and velocity measurements of the spray flow were conducted under the operating conditions such as liquid flow rate, shaping airflow rate, bell rotational speed, and electrostatic voltage setting. The optical techniques used in here were a microscopic and light sheet visualization by a copper vapor laser, and a phase Doppler particle analyzer (PDPA) system. Water was used as paint surrogate for simplicity. The results show that the bell rotating speed is the most important influencing parameter for atomization processes. Liquid flow rate and shaping airflow rate significantly influence the spray structure. Based on the microscopic visualization, the atomization process occurs in ligament breakup mode, which is one of three atomization modes in rotating atomizer. In the spray transport zone, droplets tend to distribute according to size with the larger drops on the outer periphery of spray. In addition, the results of present study provide detailed information on the paint spray structure and transfer processes.

• Journal of Environmental Science International
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• v.17 no.8
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• pp.925-932
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• 2008

Manufactures of automotive repair finishes are tending to reduce more and more the level of volatile organic compounds (VOCs) in their paint processes in order to comply with increasingly strict environmental legislation. The production of high solids paints is a way to solve this problem. However, the application of high-solids paints is limited primarily by the viscosity of resin which is strongly related to painting ability: the higher solid content, the lower desired property. In this study, alkyl copolymer with low viscosity was synthesized by the introduction of the monomers with long-side chains and functional groups which improve flexibility and cross-linking density, respectively. The solid content of the paint prepared with the synthesized resin was 80wt% and its VOCs was reduced by 20%, compared to the commercialized paint. Also, the physical and mechanical properties of coatings on steel sheets were similar to commercialized one.

• KIEAE Journal
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• v.9 no.1
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• pp.47-53
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• 2009

To know the effect of smells from eco-friend and existing interior construction materials to human response, EEG of subjects' were measured. EEG signals were measured from 8 electrodes according to the international 10-20 system (Fp1, Fp2, F3, F4, Fc3, Fc4, P3, P4) from 10 healthy subjects in seven odor construction material. Followings are results. When stimuli of smell were suggested, non-stimuli pattern of ${\alpha}$-wave is largely in right occipitallobe part and rare in frontallobe part respectively. In case of eco-friend materials' smell, there is a activation of EEG in right occipitallobe part for every stimuli. But in case of eco-friend paint and Hwang-to, ${\alpha}$-wave is appeared in most part of brain even in frontallobe part. Especially for wet cedar case, activation of brain is very positive in right occipitallobe part and in frontallobe part. When comparing the normalized sensitivity of ${\beta}$-wave which appears in negative response, the preference ratio order is like this. Normal paint ${\rightarrow}$ MDF ${\rightarrow}$ Eco-friend paint ${\rightarrow}$ Gypsum board ${\rightarrow}$ Cedar ${\rightarrow}$ Wet cedar ${\rightarrow}$ Hwang-to.

• Journal of the Korean institute of surface engineering
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• v.49 no.1
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• pp.1-13
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• 2016

This review deals with one of the surface modification techniques, chemical conversion coating and particularly cerium-based conversion coatings (CeCC) as a promising substitute for chromium and phosphate conversion coating on magnesium and its alloys. The CeCCs are commonly considered environmentally friendly. The effects of surface preparation, coating thickness, bath composition, and e-paint on the corrosion behavior of CeCCs have been studied on the AZ31 magnesium alloy. This review also correlates the coating microstructural, morphological, and chemical characteristics with the processing parameters and corrosion protection. Results showed that the as-deposited coating system consists of a three layer structure (1) a nanocrystalline MgO transition layer in contact with the Mg substrate, (2) a nanocrystalline CeCC layer, and (3) an outer amorphous CeCC layer. The nanocrystalline CeCC layer thickness is a function of immersion time and cerium salt used. The overall corrosion protection was crucially dependent on the presence of coating defects. The corrosion resistance of AZ31 magnesium alloy was better for thinner CeCCs, which can be explained by the presence of fewer and smaller cracks. On the other hand, maximum corrosion protection was achieved when AZ31 magnesium samples with thin CeCCs are e-painted. The e-paint layer further restricts and hinders the movement of chloride and other aggressive ions present in the environment from reaching the magnesium surface.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.1
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• pp.75-84
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• 2021

In this study, to evaluate deterioration propagation life and deterioration curve of the shop painted and field re-painted steel bridges, accelerated corrosion tests were carried out on 4 types of heavy-duty painting systems with different surface treatments. The surface treatments prior to painting were examined by hand tool(SSPC SP-2), power tool(SP-3,) or blast cleaning(SP-10) considering shop painting and field re-painting. The paint deterioration curves for each painting system and surface treatment were evaluated based on corrosion propagation from the initial paint defects. From the test results, the paint deterioration life of shop painted and field re-painted system was evaluated and compared by using corrosivity categories and durability performance evaluation of structural steel. The deterioration propagation life of shop and field paint was estimated in 18 to 21 years and 5.3 to 8.0 years with atmospheric corrosion category C4.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.64-68
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• 2009

It has been observed that coated steel structures deteriorate more rapidly than the designed lifetime due to acid rain caused by air pollution, etc. Therefore, improving the corrosion resistance of anti-corrosive paint is very important in terms of safety and the economic point of view. In this study, the corrosion resistance of five kinds of anti-corrosive paints, including the Acryl, Fluorine, and Epoxy resin series, were investigated with electrochemical methods, such as corrosion potential measurements, polarization curves, diffusion limiting current density, etc. As a result, the corrosion resistance of the F101 specimen with the fluorine resin series was found to be superior to the other specimens, while E100 with the epoxy resin series also showed a somewhat good corrosion resistance. Furthermore, it was observed that the amount of water and oxygen entering the inner side of a painted film increased with an increase in immersion time, irrespective of the kind of resin series. However, the oxygen diffusion limiting current density of a specimen with good corrosion resistance was relatively decreased compared to other specimens, because of the difficulty of oxygen diffusion penetrating to the inner side of the film. Consequently it is suggested that we can qualitatively evaluate the corrosion resistance of an anti-corrosive paint by measuring the diffusion limiting current density as an electrochemical method.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.193-193
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• 2003

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.585-591
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• 2013

A robot automation system for coating uniformly a big radiator used in PPS(Packaged Power Station), which consists of 6-axis robot with spray gun, travelling vehicle, supply device of coating paint and thinner with pressured air, HMI controller and robot path OLP(Off-Line Programming), was developed. Experimental results on an optimum operation condition show that a coating thickness is $43{\mu}m$, which is satisfied to a design reference of $25-100{\mu}m$. A productivity of the developed coating robot automation system based on OLP is about 12.6 times of that of manual operation.

• Corrosion Science and Technology
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• v.13 no.1
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• pp.15-19
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• 2014

Recently, anti-fouling paints which does not include the poison components such as tin(Sn), copper(Cu) have been increasingly developed in order to inhibit the environmental contamination of the sea water. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical point of view. In this study, five types of anti-fouling paints as self polishing type were investigated on the relationship between their polarization characteristics and wear ratios. It was verified that there was apparently a good relationship between the wear ratio and polarization characteristics, for example, the wear ratio increased with increasing the impedance ratio, and increased or decreased with the corrosion potential shifting in the negative or positive direction respectively. In addition, the wear ratio decreased with decreasing the corrosion current density. Consequently, it is suggested that we can qualitatively expect the wear ratio by only measuring the polarization characteristics. Therefore, before the examination of the wear ratio was actually carried out in the field, the evaluation of polarization property in the laboratory may give a available reference data for their developments.

• 전자공학회논문지 IE
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• v.47 no.2
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• pp.47-53
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• 2010

The purpose of this paper is to build on automatic system for the shot ball transfer hoist. The shot ball is used to remove completely paint or leftovers before spreading the new paint on a large vessels surface. The shot ball is made of melted iron through cooling process, and it is transferred to hopper by electromagnet of hoist. Currently, the transfer process of the shot ball is performed by manual operation, and the transfer process is inefficient. So we have developed an automatic system to replace the manual system. The developed automation systems have efficient and accurate position control performance.