• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.521-527
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• 2017

Phosphorus is one of the limiting nutrients for the growth of phytoplankton and algae and is therefore one of leading causes of eutrophication. Most phosphorous in water is present in the form of phosphates. Different technologies have been applied for phosphate removal from wastewater, such as physical, chemical precipitation by using ferric, calcium or aluminum salts, biological, and adsorption. Adsorption is one of efficient method to remove phosphates in wastewater. To find the optimal media for phosphate removal, physical characteristics of media was analysed, and the phosphate removal efficiency of media (silica sand, slag, zeolite, activated carbon) was also investigated in this study. Silica sand showed highest relative density and wear rate, and phosphate removal efficiency. Silica sand removed about 36% of phosphate. To improve the phosphate removal efficiency of silica sand, Fe coating was conducted. Fe coated silica sand showed 3 times higher removal efficiency than non-coated one.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.81-82
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• 2022

Al and Zn are used to protect the steel structures from corrosion. In the present studies, 15Al-85Zn alloy wires has been used for the deposition of coating by arc thermal spray process. Moreover, this process of coating exhibited severe defects formation, therefore, this coating was post-treated with different concentrations i.e. 0.05, 0.1 and 0.5M sodium hexa meta phosphate (Na6[(PO3)6]: SHMP) to fill to defects of deposited coatings and assessed their corrosion resistance in 3.5 wt.% NaCl solution with exposure periods. After the treatment, the porosity of the coating reduced significantly by formation of composite oxide films onto the coating surface. Initially, 0.5 M SHMP treated coating exhibited highest in total impedance due to significant reduction of porosity but once the exposure periods are extended, the composite oxides are dissolved, thus, total impedance is decreased.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.413-417
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• 2018

The $Li_4Ti_5O_{12}$ of anode material for the hybrid capacitor was coated using $CePO_4$, $M_3(PO_4)_2$ (M=Mg, Zn). The capacitance of phosphate coated $Li_4Ti_5O_{12}$ was found to be lower than that of $Li_4Ti_5O_{12}$, whereas the equivalent series resistance was higher than that of $Li_4Ti_5O_{12}$. With an increase in cycle number, the base of cylindrical cell exhibited swelling due to gas generated from the reaction between $Li_4Ti_5O_{12}$ and electrolyte. The swelling cycle number of phosphate coated $Li_4Ti_5O_{12}$ was higher than that of $Li_4Ti_5O_{12}$ due to improvement in electrochemical stability. Based on the results, it is proposed that phosphate coating can be employed as a barrier layer to control the gassing reaction by isolating the $Li_4Ti_5O_{12}$ particle from electrolyte solution.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.2_2
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• pp.199-208
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• 2022

The steel wire or steel bar processing process applied to the manufacture of various bolts and power transmission shafts was improved by applying in-line phosphate film treatment technology. By applying a polymer lubricant for a non-reactive metal forming process and a non-reactive non-phosphorus lubricating coating agent, the film formation for each process time was comparatively analyzed and reviewed. Compared to the nine processes applied previously, the in-line phosphate film treatment technology applied with only two processes has been effectively improved in terms of reduction of treatment time, reduction of facility installation area, prevention of water pollution due to wastewater, and non-use of ozone-depleting substances. In addition, it was found that it can have an important effect on productivity improvement and price competitiveness from the simplification of quality control and process control as well as improvement of the working environment.

• Journal of Applied Reliability
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• v.1 no.2
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• pp.95-108
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• 2001

To enhance the corrosion resistance of a bolt by surface treatment, dacrotization was considered as a substitute for phosphate coating which is widely used for general applications. In this study, comparisons were made among 5 different kinds of surface treatments including dacrotization and phosphate coating with respect to corrosion resistance, adhesion property with painting, and preload when tightened. The result shows that the dacrotized and surface-stabilized bolt is much superior in every aspects studied herein to others. An excellent corrosion resistance and a fairly good adhesion property with painting were achieved in the dacrotized and surface-stabilized bolt. When tightened at the same torque, the amount of preload and its deviation of dacrotized and surface-stabilized bolt were comparable with those of phosphate coated bolt.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.1
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• pp.84-90
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• 2010

The cold forging Process applies surface lubricant coating in order to smooth the friction during the cold forging process. Currently, most of the lubrication processes apply the zinc phosphate coating, which requires 11 steps and disposes sludge. But the water based lubrication process, which has been newly developed, takes 3 steps only and does not cause sludge. In this study, we present the optimal condition of water based lubrication for the cold forging of axle shaft by an experimental design method. Experimental results with minitab shall be able to predict the optimum water based lubricating conditions for the cold forging processes.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.795-804
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• 2007

Statement of problem. Nano-scale calcium-phosphate coating on the anodizing titanium surface using ion beam-assisted deposition (IBAD) has been recently introduced to improve the early osseointegration. However, not much is known about their surface characteristics that have influence on tissue-implant interaction. Purpose. This study was aimed to investigate microtopography, surface roughness, surface composition, and wettability of the titanium surface modified by the anodic oxidation and calcium phosphate coating using IBAD. Material and methods. Commercially pure titanium disks were used as substrates. The experiment was composed of four groups. Group MA surfaces represented machined surface. Group AN was anodized surface. Group CaP/AN was anodic oxidized and calcium phosphate coated surfaces. Group SLA surfaces were sandblasted and acid etched surfaces. The prepared titanium discs were examined as follows. The surface morphology of the discs was examined using SEM. The surface roughness was measured by a confocal laser scanning microscope. Phase components were analyzed using thin-film x-ray diffraction. Wettability analyses were performed by contact angle measurement with distilled water, formamide, bromonaphtalene and surface free energy calculation. Results. (1) The four groups showed specific microtopography respectively. Anodized and calcium phosphate coated specimens showed multiple micropores and tiny homogeneously distributed crystalline particles. (2) The order of surface roughness values were, from the lowest to the highest, machined group, anodized group, anodized and calcium phosphate deposited group, and sandblasted and acid etched group. (3) Anodized and calcium phosphate deposited group was found to have titanium and titanium anatase oxides and exhibited calcium phosphorous crystalline structures. (4) Surface wettability was increased in the order of calcium phosphate deposited group, machined group, anodized group, sandblasted and acid etched group. Conclusion. After ion beam-assisted deposition on anodized titanium, the microporous structure remained on the surface and many small calcium phosphorous crystals were formed on the porous surface. Nanoscale calcium phosphorous deposition induced roughness on the microporous surface but hydrophobicity was increased.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.195-198
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• 2006

Zinc phosphate coating is required in nearly all steel cold forging operations. However, the chemical byproducts of this lubricant system are difficult to dispose of and have a negative environmental impact. In order to replace zinc phosphate based lubricants partially or completely, candidate lubricant has been developed in this study. The performance evaluation of these lubricants was conducted using the double cup extrusion test and spike forging test. With the use of the commercial FEM code DEFORM, friction factor calibration curves, i.e. cup height ratio vs. punch stroke and spike height vs. punch stroke, were established for different friction factor values. By matching the cup height ratio and the punch stroke and spike height vs. punch stroke from experiment to that obtained from FE simulations, the friction factor of the lubricants was determined. Three water-soluble lubricants; namely, Mec Homat, Royalcoat, and the developed lubricant were found to perform comparable to or better than zinc phosphate.

• Journal of the Korean institute of surface engineering
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• v.43 no.2
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• pp.73-79
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• 2010

A chromium-free conversion coating for AZ31 magnesium alloy has been obtained by using a permanganatephosphate solution, which has been developed with acid pickling. Examination have been carried out on the conversion coatings for morphology, composition and corrosion resistance. The morphology of the conversion-coated layer was observed using optical microscope and SEM. It was shown that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to 2.7 ${\mu}m$. The chemical composition of conversion coating was mainly consisted of Mg, O, P, K, Al and Mn by EDS analysis. It was found that the corrosion resistance of the AZ31 magnesium alloy has been improved by the permanganate-phosphate conversion treatment from electrochemical polarization.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.149-154
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• 2007

The zinc prosphate film treatments used to lubricating treatment of mostly cold forging processes. But there are several problems happened to lubricating treatment process such as happening harmful environment on person, complex lubrication processing occurring in energy and time consumption, eco-destructive and chemical by-product generation, the needs of waste disposal etc. As a result, a water-soluble lubricant was developed to replace the perfect or some of the zinc prosphate film in the world. In order to solve these problems, this study evaluated the performance of the typical water-soluble. In this study, for these requirement inquiry of two part. First, about possibility of replace zinc phosphate lubricant, quantitatively evaluation developed of water-soluble lubricant for cold forging vs zinc phosphate lubricant. Second, About optimization of coating Process use to equipment with practicable automatic coating Process. The performance evaluation of these lubricants was conducted using the double cup extrusion test and spike forging test. With the use of the commercial FE code DEFORM, friction factor calibration curves, i.e. cup height ratio vs. punch stroke and spike height vs. punch stroke, were established for different friction factor values. By matching the cup height ratio and the punch stroke and spike height vs. punch stroke from experiment to that obtained from FE simulations, the friction factor of the lubricants was determined. Survey of comparative analysis use to SEM that sprayed lubricant surface structure of grain shape and characteristic of lubricant performance based on grain shape and deformed lubricant surface expansion. As a result, developed lubricant were found to perform comparable to or better than zinc phosphate. And thought this result, innovatively cope with generated problem of existing lubrication process.