Mg 합금의 PEO 공정 조건에 따른 산화피막 결정상과 내부식성에 대한 연구 II. 내부식성

김배연,김용남,전민석,함재호,Kim, Bae-Yeon,Kim, Yong-Nam,Jeon, Min-Seok,Ham, Jae-Ho 한국결정성장학회 2018 한국결정성장학회지 Vol.28 No.2

AZ31과 AZ91 Mg 합금을 Na-P 및 Na-Si 전해질을 사용하여 전해질의 농도, 인가전압, 처리시간에 따라 여러가지 조건에서 PEO 처리하여 5%의 농도를 갖는 염수분무법으로 내부식성 연구를 하였다. 일반적으로 산화피막 코팅 두께가 증가하면 내부식성이 증가하였다. 코팅두께보다 산화피막 표면의 기공크기가 커지면 장기 내부식성은 나빠지는 경향을 보인다. 산화피막의 전체적인 산화물 결정상이 증가할수록, 또 MgO 결정상 대신 $Mg_2SiO_4$ 상과 같은 다른 결정상이 증가할수록 내부식성이 월등히 증가하는 것을 알 수 있었다. Mg alloys AZ31 and AZ91 were Plasma-Electrolytic-Oxidized in Na-P and Na-Si system electrolyte at various concentration, applied voltage and time. Thickness and surface roughness of PEO coating were examined. Salt spraying test were carried out to compare their corrosion resistances. Generally, corrosion resistances rate were increased as thickness and crystallinity increasing. Size of pore being larger, long term corrosion resistance decreased. It is turned out that $Mg_2SiO_4$ and other crystalline phase rather than MgO might be increase corrosion resistance dramatically.

Ion Implantation으로 Ca를 첨가한 단결정 $Al_2$O$_3$의 Crck-Like Pore의 Healing 거동-H. Hexagonal Ligaments and Type of Healing

김배연 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.8

Ion implantation, photo-lithography, Ar ion milling과 hot press 법을 이용한 micro-fabrication techrique을 사용하여 고순도 알루미나 단결정인 사파이어의 내부에, 조절된 Ca의 첨가량을 갖고 있는, crack과 비슷한 형태의 기공들을 형성시켰다. 이 bi-cryslal을 각각의 온도에서 열처리하여 Ca 이온이 고온에서 알루미나의 morphology와 hcaling에 미치는 영향을 관찰하였다. 열처리 온도가 올라감에 따라서 crack-like pore의 내부에 hcxagonal bridging ligaments가 생성되었는데, 열처리 온도와 Ca의 첨가량이 증가할수록 크기가 커지는 것을 관찰할 수 있었고, 생성된 hexagonal bndgmg ligaments는 열처리가 진행됨에 따라 서서히 커지면서 모서리가 둥글어지는 현상을 관찰할 수 있었다. Bicrystal 내부에 형성된 crack-like pore는 열처리가 진행되면서 edge regression. ligamcnt growth 및 flow의 3가지의 특징적인 형태로 진행되었다. 이때 edge regression은 상대적으로 저온에서부터 전체 crack-like pore에서 서서히 일어나기 시작하였으며, ligament growth는 일부 crack-like pore에서 진행되있으며, 대단히 빠른 속도로 crack healing이 진행됨을 추정할 수 있었다. Flow는 $1800^{\circ}C$ 이상의 고온에서 모든 crack-like pore에 걸쳐서 느리게 일어남을 알 수 있었다. Inner crack-like pores with controlled amount of Ca impurity level in the high purity alumina single crystal sapphire had been created by micro-fabrication technique which includes ion implantation photo-lithography Ar ion milling and hot press technique. The morphological change and the healing of crack-like pore in the Ca doped high purity single crystal alumina during high temperature heat treatment in vacuum were observed using optical microscopy. The hexagonal bridging ligaments were developed and the size of hexagonal bridging ligaments had been increased with temperature and Ca amount and had grown to their corner rounded. It appeared that the hexagonal bridging ligaments would have an equilbrium size with temperature and the amount of Ca addition. Three kinds of crack-like pore healing type were observed. Edge regression and ligament growth were observed from relatively low temperature in the crack-like pore. Edge regression were found in almost all of the crack-like pore but the ligament growth were found only in the several crack-like pores accelerating heating very fast. Flow type healing was observed above $1800^{\circ}C$ and It healed the crack-like pore very slowly.

Ion Implantation으로 Ca를 첨가된 단결정 $Al_2$O$_3$의 Crack-Like Pore의 Healing 거동-III: Stability of Crack-Like Pore

김배연 한국세라믹학회 1999 한국세라믹학회지 Vol.36 No.9

The inner crack-like pore with controlled amount of Ca impurity in the high purity alumina single crystal sapphire had been created by micro-fabrication technique which includes ion implanation photo-lithography Ar ion milling and hot press technique. The crack-like pores in two-hour hot pressed specimen were extremely stable even after heat treating at 1,80$0^{\circ}C$ for 5 hours almost no healing was observed. But the crack-like pores in one-hour hot pressed specimen at 1,30$0^{\circ}C$ were healed by heat treatment and the amount of healing was increased with the heat treatment time and temperature and the amount of Ca addition. The edges of crack-like pore parallel to <1100> direction in (001) basal plane were stable but the edges normal to this direction in (00101) plane <1120> direction were unstable to facetting This means that the surface energy of alumina along the <1100> direction in (0001) basal plane in much lower than <1120> direction.

플라즈마 전해 산화 코팅에 있어서 알루미늄 합금 모재 성분의 물리적, 결정학적 영향 I. PEO 층의 물성

김배연,이득용,김용남,전민석,송준광,김성엽,김광엽,Kim, Bae-Yeon,Lee, Deuk-Yong,Kim, Yong-Nam,Jeon, Min-Seok,Song, Jun-Kwang,Kim, Sung-Youp,Kim, Kwang-Youp 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.3

Physical properties of Plasma electrolytic oxidized 8 different types of Al alloys, A-1100, A-2024, A-5052, A-6061, A-6063, A-7075, ACD-7B and ACD-12 were investigated. The electrolyte for PEO was $Na_2SiO_3$ solutions with NaOH and some alkali earthen metal salts. Porous layer near the surface of PEO coating was not found, and surface roughness Ra50 was below 2.5 ${\mu}m$. Surface roughness was affected by growth rate of plasma electrolytic oxidized layer, not by Si content in Al alloy.

마이크로 유기-무기 복합체가 포틀랜드 시멘트 수화에 미치는 영향(I) MontmorillonitPVA 층간 화합물의 형성

김배연,김창은,최진호 한국세라믹학회 1985 한국세라믹학회지 Vol.22 No.4

For studying the influence of addition of Polyvinyl alcohol (PVA)-montmorillonite complex on the hydration of Portland cement the PVA-montmorillonite derivatives were prepared in advance an characterized system-of Portland cement the PVA-montmorillonite derivatives were prepared in advance and characterized systema-tically. PVA with the polymerizationdegree ranging from 500 to 2000 have been intercalated into the lamellar structure of hydrated montmorillonites which were fractionated under 2㎛ by Stock's rule. In all cases the constant basal spacing of ∼20Å was determined whatever the molecular weight of PVA used. And the carbon chain orientation of PVA in the interfoliar space has been deduced to be parallel with bilayer structure.

$Ca^{++}$를 implant한 단결정 $Al_2O_3$에서 열처리에 의한 형태학적 변화

김배연 한국결정성장학회 1999 韓國結晶成長學會誌 Vol.9 No.3

Ion implantation, photo-lithography, Ar ion milling, hot press를 이용한 micro-fabrication 방법으로 고순도 단결정 알루미나 표면에 Ca를 제한된 양으로 첨가하고, 내부에 여러 가지 형태의 기공을 갖는 bi-crystal을 만들었다. 이 bi-crystal 고순도 알루미나에 미치는 Ca의 영향을 평가하기 위하여 내부 기공의 형태 변화와 결정의 성장을 열처리에 따라 광학현미경으로 관찰하였다. 열처리에 따라 inner crack-like pore의 내부표면에 dot와 육각형의 형태를 갖는 결정 입자가 생성되는 것을 관찰할 수 있었다. $1,500^{\circ}C$로 열처리한 경우에 CaO . $6Al_2O_3$로 생각되는 bar 형태의 결정이 표면에 석출되는 것이 관찰되었으며, 이 결정이 $1,600^{\circ}C$에서 열처리하면 사라지는 것으로 보아 이 온도 부근에서 알루미나에 대한 Ca의 solubility limit 또는 diffusion rate가 변화하는 것으로 생각된다. Controlled Ca impurity implanted inner crack-like pore in the high purity alumina bi-crystal had been created by micro-fabrication technique, which includes ion implantation, photo-lithography, Ar ion milling, and hot press. The morphological change and the growth od crystals formed by heat treatment in Ca doped high purity single crystal alumina, were observed using optical microscopy. The dot was developed and hexagon like crystal appeared on inner surface of crack-like pore after heat treatment. Bar type crystals, probably CaO . $6Al_2O_3$, were observed on the inner surface of 100ppm Ca implanted specimen after 1 hour heat treatment at $1,500^{\circ}C$, but this bar type crystal disappeared after 1 hour heat treatment at $1,600^{\circ}C$. This disappearance means that there should be little increase of Ca solubility limit to alumina and/or changes of diffusion coefficient of Ca in alumina around this temperature.

Mg 합금의 PEO 공정 조건에 따른 산화피막 결정상과 내부식성에 대한 연구 I. 결정상

김배연,김용남,전민석,함재호,Kim, Bae-Yeon,Kim, Yong-Nam,Jeon, Min-Seok,Ham, Jae-Ho 한국결정성장학회 2018 한국결정성장학회지 Vol.28 No.2

내부식성이 약해서 응용이 제한되고 있는 Mg 합금 AZ31과 AZ91의 내부식성을 향상시키기 위하여 Na-P 및 Na-Si 전해액을 사용하여 공정조건에 따라 PEO 처리를 하여 표면 피막의 결정상과 morphology를 관찰하였다. PEO 처리한 표면 산화피막에서 가장 흔히 발견되는 결정상은 MgO이며 비정질상의 존재도 알 수 있었다. 전해액에서부터 비롯된 Na, P 및 Si 성분이 산화피막의 형성에 첨가되어 $Na_{3.59}Mg_{2.71}(PO_4)_3$ 상과 $Mg_2SiO_4$ 결정상이 관찰되었다. 산화표면은 PEO 처리 전압, 전해질 농도, 처리 시간에 따라서 기공율이 감소하다가, 이후 기공율과 기공의 크기가 증가하는 경향을 관찰할 수 있었다. To increase corrosion resistance of Mg alloy, AZ31 and AZ91 were PEO treated with different applied voltage and time conditions. We used Na-P and Na-Si system electrolyte. Crystalline phase and morphology were investigated. MgO was Most common crystal phase and vitreous phase could be found. Crystalline phase of $Na_{3.59}Mg_{2.71}(PO_4)_3$ and $Mg_2SiO_4$ also could be found. Porosity of oxidized surface tends to decrease with increasing PEO applied voltage, treat time and concentration of electrolyte, after then, size of pore increased and total number of pore decreased, distinctly.

Screen Printable MoSi2 도전성 Paste를 이용한 세라믹 면상 발열체 제조

김배연,한동빈,정철원 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.4

Screen printable MoSi2 paste and its ceramic sheet heater were investigated. MoSi2 powder without Mo5Si3 second phase, which causes so-called pest phenomena, was synthesized by SHS technique. Over glaze was also developed for preventing pest phenomenon. The maximum temperature of MoSi2 ceramic heater was over 500oC. After several heat up and cooling cycle, the MoSi2 heater reveals pest phenomenon. Conductive MoSi2 paste could be used in electronic ceramics, i.e., MLCC, LTCC, HTCC, and etc.

플라즈마 전해 산화 코팅에 있어서 알루미늄 합금 모재 성분의 물리적, 결정학적 영향 II. PEO 층의 결정상 분석

김배연,이득용,신민철,신현규,김병곤,김성엽,김광엽 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.4

Physical properties of Plasma electrolytic oxidized 8 different kinds of Al alloys, A-1100, A-2024, A-5052, A-6061, A-6063, A-7075, ACD-7B and ACD-12 were investigated. The electrolyte for PEO was Na2SiO3 and NaOH and some alkali earthen metal salts system solution. η-alumina, as well as γ-alumina, was main crystal phase, which were ever reported. Also, Al4.95Si1.05O9.52 was found only in this research. So we can conclude that the process conditions of PEO apparatus and composition and concentration of its electrolyte affects crystal structure and physical properties of PEO layers much more than the compositions of Al alloy.

플라즈마 전해 산화 코팅에 있어서 인산염 전해액과 모재 성분 변화가 Al 산화피막 물성에 미치는 영향 I. PEO층의 물성

김배연,김정곤,이득용,전민석,김용남,김성엽,김광엽,Kim, Bae-Yeon,Kim, Jeong-Gon,Lee, Deuk-Yong,Jeon, Min-Seok,Kim, Yong-Nam,Kim, Sung-Youp,Kim, Kwang-Youp 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.3

Physical properties of plasma electrolytic oxidized layers of 8 different kinds of Al alloys, A-1100, A-2024, A-5052, A-6061, A-6063, A-7075, ACD-7B and ACD-12 were investigated. The electrolyte for plasma electrolytic oxidation was mixture of distilled water, $Na_2P_2O_7$, KOH and some metal salts. Growth rate of oxide layer was slower in $Na_2P_2O_7$ electrolyte system than in $Na_2SiO_3$ system, and Ra50 surface roughness of oxidized layer was below $1.2{\mu}m$. Surface hardness in $Na_2P_2O_7$ electrolyte system is higher than in $Na_2SiO_3$ system, and roughness was lower in $Na_2P_2O_7$ electrolyte system than in $Na_2SiO_3$ system.