• Title/Summary/Keyword: phosphate coating treatment

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Effect of Phosphate Surface Treatment on the Localized Corrosion Resistance of UNS G41400 Steel (UNS G41400 강의 인산염 표면 처리에 따른 국부 부식 저항성)

  • Jun-Seob Lee;Siwook Park
    • Corrosion Science and Technology
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    • v.22 no.6
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    • pp.429-434
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    • 2023
  • This study investigated the localized corrosion behavior of a UNS G41400 steel surface treated with manganese phosphate. The phosphate coating, primarily composed of oxygen (O), phosphorus (P), and manganese (Mn) elements, had an approximate thickness of 6 ㎛. The particles comprising the coating varied in size by several micrometers; smaller particles were mainly composed of O, P, Mn, and iron (Fe) elements, indicating incomplete formation of the manganese phosphate film. Potentiodynamic polarization curves revealed a decrease in anodic current after surface treatment and a shift in corrosion potential toward the noble direction after treatment. After immersion in a 3.5 wt% NaCl solution for 96 hours, localized corrosion was observed, with some regions retaining residual phosphate film. Even though localized corrosion occurred on the treated surface, it was less severe than that on the untreated UNS G41400 steel surface. These findings suggest that manganese phosphate coating improved resistance to localized corrosion.

Characteristics of Environmentally-Friendly Conversion Coating of AZ31 Magnesium Alloy by a Alkaline Phosphate-Permanganate Solution (알카리성 인산-과망간산 용액을 이용한 AZ31 마그네슘 합금의 친환경 화성 처리 및 화성 피막의 특성 평가)

  • Kim, Myung-Hwan;Lee, Man-Sig;Kwag, Sam-Tag;Moon, Myung-Jun
    • Journal of the Korean institute of surface engineering
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    • v.44 no.3
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    • pp.82-88
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    • 2011
  • A uniform chromium-free conversion coating treated with an alkaline phosphate- permanganate solution was formed on the AZ 31 magnesium alloy. The effect of acid pickling on the morphology and on the corrosion resistance of the alkaline phosphate-permanganate conversion coating was investigated. The chemical composition and phase structure of conversion coating layer were determined via optical microscopy, SEM, EDS, XPS and XRD. Results show that the conversion coatings are relatively uniform and continuous, with thickness 1.8 to $2.4\;{\mu}m$. The alkaline phosphate-permanganate conversion coating was mainly composed of elements Mg, O, P, Al and Mn. The conversion-coated layers were stable compounds of magnesium oxide and spinel ($MgAl_2O_4$). These compounds were excellent inhibitors to corrosion. The electrochemical corrosion behaviors of coatings in 3.5 wt.% NaCl solutions were evaluated by electrochemical impedance spectroscopy, potentiodynamic polarization technique. EIS results showed a polarization resistance of $0.1\;k{\Omega}$ for the untreated Mg and $16\;k{\Omega}$ for the alkaline phosphate-permanganate conversion treatment sample, giving an improvement of about 160 times. The results of the electrochemical measurements demonstrated that the corrosion resistance of the AZ 31 magnesium alloy was improved by the alkaline phosphate-permanganate conversion treatment.

Research on the Development of Inline Phosphate Coating Process Technology to Secure the Properties of Parts for Power Transmission Machinery (동력전달용 기계부품의 물성 확보를 위한 인라인 인산염 피막처리 공정기술개발)

  • Kim, Deok-Ho;Ku, Young-Jin
    • 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.

Study on the coating weight and corrosion resistance of Zinc phosphate for surface treatment of ammunition (탄약 표면 처리용 아연계 인산염 피막의 중량 및 내식성에 관한 연구)

  • Kim, Myung-Hyun;Lee, Seung-Yong;Lee, Hyun-Hee;Lee, Young-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.10
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    • pp.603-610
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    • 2017
  • Steel used for various industrial fields including ammunition is vulnerable to corrosion so surface treatments are required such as plating, painting and chemical conversion coating. Zinc phosphate, used for ammunition manufacturing, is used to stick the stable compound on the surface by chemical conversion of metal. The quality of phosphate coating depends on many factors such as total acidity and iron content. In this study, we studied the influence of total acidity and iron content on coating weight and corrosion resistance of phosphate coating. The surface structure of the coating becomes dense and corrosion resistance is improved with increasing iron content. However, total acidity influences only the thickness and phosphate coating weight. In conclusion, this study suggests the optimal range of total acidity and iron content to manufacture the ammunition.

Development of Hybrid Sol-Gel Coating to Prevent Corrosion of Magnesium Alloys (마그네슘 합금의 방청을 위한 하이브리드 졸-겔 코팅제의 개발)

  • Lee, Dong Uk;Kim, Young Hoon;Moon, Myung Jun
    • Corrosion Science and Technology
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    • v.17 no.1
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    • pp.30-36
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    • 2018
  • The high rate of corrosion of magnesium alloys makes it limited for industrial applications. Therefore, surface treatment is required to enhance their corrosion resistance. In our study, a chemical conversion coating for protecting the corrosion of the magnesium alloy, AZ31B, was prepared by using a phosphate-permanganate solution. The chemical conversion coating had a limited protection ability due to defects arising from cracks and pores in the coating layer. The sol-gel coating was prepared by using trimethoxymethylsilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors, and aluminum acetyl acetonate as a ring opening agent. The corrosion protection properties of sol-gel and conversion coatings in 0.35wt% NaCl solution were measured by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test. The EIS results indicated that the resistance of the chemical conversion coating with the sol-gel coating was significantly improved through the sol-gel sealed phosphate-permanganate conversion coating. The results of the potentiodynamic polarization test revealed that the sol-gel coating decreased the corrosion current density ($I_{corr}$). The SEM image showed that the sol-gel coating sealed conversion coating and improved corrosion protection.

Effect of sodium hexa-meta phosphate as pore-sealing agent on the corrosion performance of Al-Zn coating deposited by twin-wire arc thermal spray process in 3.5 wt.% NaCl solution (3.5 중량% NaCl 용액에서 쌍선 아크 용사 공정으로 증착된 Al-Zn 코팅의 부식 성능에 대한 기공 밀봉제로서의 헥사메타인산나트륨의 영향)

  • Singh, Jitendra Kumar;Adnin, Raihana Jannat;Lee, Han-Seung
    • 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.

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A Study on the Acid Drainage Neutralizing System for Ecological Vegetation on the Acid Drainage Slope (산성배수 비탈면의 생태적 녹화를 위한 산성배수 중화기법 연구)

  • Cho, Sung Rok;Shim, Sang Ryul;Kim, Jae Hwan
    • Journal of the Korean GEO-environmental Society
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    • v.20 no.1
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    • pp.27-33
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    • 2019
  • Research was initiated to find out acid drainage neutralizing techniques for ecological vegetative growth on the acid drainage slope. Four different acid drainage neutralizing techniques [no treatment, limestone layer treatment, phosphate treatment, and limestone layer + phosphate treatment] were treated on the acid drainage slope. There was a significant difference observed in treated acid neutralizing techniques for acidity, surface coverage rate, death rate and plant root status. Treated acid neutralizing techniques were effective for neutralizing acidity and vegetative growth in order of [first: limestone layer + phosphate treatment, second: phosphate treatment, third: limestone layer treatment and fourth: no treatment]. The limestone layer and the phosphate treatments were effective for neutralizing acidity and vegetative growth, respectively. However, the phosphate treatment was more effective compared to the limestone layer treatment on the acid drainage slope. We figured out that the phosphate treatment is more effective for neutralizing acidity and vegetative growth because of coating effect of sulfides.

Characterization of Dacrotized Bolts (다크로 방식 처리된 볼트의 특성 평가)

  • Yang, Chi-Hoon;Ko, Jeong;Kim, Dae-Yong
    • 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.

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Evaluation of water-Soluble Lubricant for Cold Forging and Optimization of Coating Process (냉간단조용 수용성 윤활제의 평가 및 윤활 처리 공정의 최적화)

  • Lim, W.J.;Lee, I.S.;Je, J.S.;Ko, D.C.;Kim, B.M.
    • 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.

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Characteristics Evaluation of Conversion Coating of Acid Pickling AZ31 Magnesium Alloy by a Chromium-Free Phosphate-Permanganate Solution (비크롬계 인산-과망간산 용액을 이용한 AZ31 마그네슘 합금의 산처리에 따른 화성 피막의 특성 평가)

  • Kim, Myung-Hwan;Kwag, Sam-Tag;Moon, Myung-Jun
    • 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.