• Corrosion Science and Technology
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• 제17권1호
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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.

• Corrosion Science and Technology
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• 제20권4호
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• pp.175-182
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• 2021

Magnesium alloy is limited in the industrial field because its standard electrode potential is -2.363 V vs. NHE (Normal Hydrogen Electrode) at 25 ℃. This high electrochemical activity causes magnesium to quickly corrode with oxygen in air; chemical conversion coating prevents corrosion but causes surface defects like cracks and pores. We have examined the anti-corrosion effect of sol-gel coating sealed on the defected conversion coating layer. Sol-gel coatings produced higher voltage current and smaller pore than the chemical conversion coating layer. The conversion coating on magnesium alloy AZ31 was prepared using phosphate-permanganate solution. The sol-gel coating was designed using trimethoxymethylsilane (MTMS) and (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) as precursors, and aluminum acetylacetonate as a ring-opening agent. The thermal shock resistance was tested by exposing specimens at 140 ℃ in a convection oven; the results showed changes in the magnesium alloy AZ31 surface, such as oxidization and cracking. Scanning electron microscope (FE-SEM) analysis confirmed a sealed sol-gel coating layer on magnesium alloy AZ31. Electrochemical impedance spectroscopy (EIS) measured the differences in corrosion protection properties by sol-gel and conversion coatings in 0.35 wt% NaCl solution, and the potentiodynamic polarization test and confirmed conversion coating with the sol-gel coating show significantly improved resistance by crack sealing.

• 한국식품영양과학회지
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• 제42권12호
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• pp.2019-2027
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• 2013

본 연구에서는 고당도, 고점도 및 저산도를 나타낼 수 있는 케이크용 신선편의 과일을 위한 코팅제를 개발하기 위하여 설탕, 펙틴, 알긴산, 카라기난, 잔탄검 및 비타민 C를 이용한 코팅제 배합비율을 선정하였고, 선정된 배합비율로 제조된 코팅제의 냉 해동 안정성 및 제조된 코팅제로 코팅한 파인애플의 저장특성을 살펴보았다. 먼저 다양한 코팅 조성물의 배합비율은 60 brix 이상의 당도와 30,000 cP 이상의 점도 및 pH 4 이하의 산도를 나타내면서 고형분 함량이 가장 낮은 55%(w/w) 설탕, 2%(w/w) 펙틴, 2%(w/w) 알긴산, 0.04%(w/w) 카라기난, 0.1%(w/w) 잔탄검, 0.05%(w/w) 비타민 C 및 40.81%(w/w) 정제수의 비율로 선정하였다. 그리고 코팅제의 냉 해동 안정성에서 점도의 경우 3회의 냉 해동 반복 과정까지는 일정하게 유지되었으나 4회 반복 과정에서는 미비하게 감소되는 경향을 나타내었다(P<0.05). 반면 당도, pH 및 색도는 4회의 반복 과정에서도 일정하게 유지되었다. 그리고 코팅제로 코팅한 파인애플의 경우 코팅하지 않은 파인애플에 비하여 중량 감소율, 경도 변화 및 일반세균수 분포가 낮게 나타났으며(P<0.05), 색도의 경우 두 파인애플 모두 저장기간이 진행될수록 L값이 감소하면서 b값이 증가하여 갈변이 일어나는 것으로 나타나지만 색도차로 비교해볼 때 코팅된 파인애플보다 코팅하지 않은 파인애플의 진행속도가 더 빠른 것으로 나타났다. 그리고 $25^{\circ}C$에서 보다 $4^{\circ}C$에서의 진행속도가 천천히 진행됨을 확인할 수 있었다. 따라서 케이크에 적용하는 신선편의 과일에 코팅제를 적용하여 코팅하고 저온에서 보관함으로써 신선편의 과일의 저장성 향상을 유도할 수 있으므로 케이크의 유통기한 향상에 기여할 수 있을 것으로 생각된다.

• 펄프종이기술
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• 제36권3호
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• pp.74-82
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• 2004

The botanical antimicrobial agent prepared from citrus fruits (BAAC) was prepared to provide inhibitory ability to packaging paper The BAAC diluted in 0.5% and 1% starch solution respectively was applied to packaging paper by the thin coating technique. The antimicrobial packaging paper displayed great inhibitory effect against the putrefying microbes including fungi, yeast and bacteria. Tn addition to antimicrobial activity of the packaging papers, their physical properties such as tensile strength, burst strength, tear strength and bending stiffness could be improved by simultaneous treatment with starch. Both the item packaging by tissue paper and the outer packaging by corrugated boxes, which were treated by the thin coating of BAAC and starch, exhibited great ability in preserving freshness of stored mandann oranges. The more treatment of BAAC was made in the packaging paper, the greater freshness-preserving ability was generated.

• 펄프종이기술
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• 제43권4호
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• pp.76-81
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• 2011

This study was carried out in order to develop a speciality functional coated paper, which can be recognized under a ultraviolet lamp. The special fluorescent whitening agent (FWA) which absorbs ultraviolet light (397~410 nm) and emits it as yellowish light (570~500nm) was used. The special FWA was applied in a coating color in two ways: (1) direct application to a coating color as a FWA; (2) application on pigment surface, drying it and application it as a fluorescence whitening pigments (colored pigments). The effects of the special FWA on coating color properties were tested and the distribution of colored pigments in coated paper was evaluated under a ultraviolet lamp. The results showed that the colored pigments didn't affect on coating color properties. Experimental results showed the possibility of producing a security coated paper using the special FWA. To produce a speciality functional paper, it was found to be proper to apply the special FWA in the form of colored pigment.

• 접착 및 계면
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• 제24권4호
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• pp.124-130
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• 2023

외부 온도 변화에 따른 특성변화가 적어야 하는 자동차 부품용 코팅제는 외부 환경 변화에 의한 노이즈 특성 변화가 매우 중요하다. 이에 내한성, 내후성, 내마모성이 우수한 연질의 폴리우레탄과 하이드록시 말단 혹은 곁사슬이 아민으로 변성된 폴리실록산 등이 널리 사용되고 있다. 본 연구에서는 각각의 폴리머 성분들이 노이즈에 미치는 영향을 확인하기 위하여 수분산 폴리우레탄을 합성하였고, 폴리실록산, ultra high molecular polypropylene (UHMWPP) 분말, 카본블랙, 소광제를 첨가하여 코팅제를 제조하였다. 수분산 폴리우레탄의 hard/soft 세그먼트의 함량을 27.1%/72.9%, 아민으로 변성된 폴리실록산과 하이드록시 말단 폴리실록산이 2:7의 비율에서 노이즈의 발생이 가장 적었으며, 마찰자가 고속에서 움직일 때 마찰계수의 차이가 컸다. 또한 SiO₂를 UHMWPP 분말로 대체함으로써, 노이즈가 감소하였으며 광택도 또한 감소하였다.

• 치위생과학회지
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• 제9권4호
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• pp.405-412
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• 2009

본 연구는 도재소부용 비귀금속에 Au 코팅 층을 형성하고, Au 코팅 층이 금속-도재의 결합력에 미치는 영향을 알아보고자 2출 굴곡 시험 후에 SEM/EDS 방법으로 조사하여 비교하였다. 1. Ni-Cr ally 군과 Co-Cr alloy 군, 그리고 Ti 군의 절단면 시편의 전자현미경 사진에서 Au 코팅 층은 산화층의 확산을 제어하는 것으로 관찰되었다. 2. 2축 굴곡 시험 후에 EDS 분석 결과 Ni-Cr alloy 군과 Co-Cr alloy 군에서 Si 함량은 Au 코팅 층을 형성한 시편에서 약간 감소하였고, 결합실패의 형태는 cohesive failure와 adhesive failure가 혼재된 양상으로 관찰되었다. 3. Ni-Cr alloy 군과 Co-Cr alloy 군에서 Au 코팅 층은 도재-금속 결합력에 미치는 영향은 미미하였다. 4. Ti 군의 결합실패 형태는 Ni-Cr alloy 군과 Co-Cr alloy 군에 비해서 adhesive failure 양상이 두드러지게 관찰되었고, Au 코팅 층은 도재-금속 결합력에 영향을 미치지 않았다. 이상의 결과 비귀금속에 적용한 Au 코팅은 산화층의 확산을 제어 하는 것으로 관찰 되었으나, 금속-도재 간의 결합력 증징에 미치는 효과는 미미하였다. Au 코팅을 이용하여 금속-도재 간의 결합력 증진을 위해서는 많은 연구가 지속되어야 할 것으로 사료된다.

• 대한화학회지
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• 제63권6호
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• pp.411-414
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• 2019

• Corrosion Science and Technology
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• 제14권5호
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• pp.207-212
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• 2015

The purpose of this research was to synthesize fluorine modified waterborne polyurethane dispersion (F-WPU) by soap-free (internal emulsifier) emulsion polymerization techniques, to prepare coating solution based on fluorine modified waterborne polyurethane dispersion (F-WPU) and to compare the chemical and thermo-mechanical properties on the electrogalvanized steel sheet. Environmentally friendly F-WPU was prepared with a fluorinated polyol containing 60 wt% of fluorine. There are various ways of combining a wide variety of fluorinated polyols and diisocyanate to exhibit novel properties of waterborne polyurethane dispersion. Components of coating solution were largely divided into 4 kinds i.e., F-WPU, acrylic emulsion, silane coupling agent, and colloidal silicate. F-WPU coating solution on the electro-galvanized steel sheet showed excellent properties of corrosion resistance, alkali resistance and heat resistance, as compared to other coating solutions using a general waterborne resin. The F-WPU coating solution's reliable effects are possibly due to the fluorine atoms incorporated even in a small amount of F-WPU.

• Corrosion Science and Technology
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• 제11권1호
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• pp.15-19
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• 2012

Both electrogalvanized and hot-dip galvanized steel sheets have been finally produced via organic-inorganic surface coating process on the zinc surface to enhance corrosion resistance and afford additional functional properties. Recently, POSCO has been developed a variety of chromate-free coated steels that are widely used in household, construction and automotive applications. New organic-inorganic hybrid coating solutions as chromate alternatives are comprised of surface modified silicate with silane coupling agent and inorganic corrosion inhibitors as an aqueous formulation. In this paper we have prepared new type of hybrid coatings and evaluated quality performances such as corrosion resistance, spot weldability, thermal tolerance, and paint adhesion property etc. The electrogalvanized steels with these coating solutions exhibit good anti-corrosion property compared to those of chromate coated steels. Detailed components composition of coating solutions and experimental results suggest that strong binding between organic-inorganic hybrid coating layer and zinc surface plays a key role in the advanced quality performances.