Layering시 복합레진 층간의 계면 결합에서 oxygen inhibition layer가 필수적인가?

김선영,조병훈,백승호,이인복 大韓齒科保存學會 2008 Restorative Dentistry & Endodontics Vol.33 No.4

본 연구의 목적은 여러 가지 계면조건의 변화를 통해서 layering 시 복합레진 층간의 결합에 oxygen inhibition layer (OIL)가 필수적인지를 고찰해보는 것이다. 가로 × 세로 × 두께가 16 × 28 × 2.5 ㎜인 알루미늄판에 지름 3.7 ㎜의 구멍을 형성하여 몰드를 제작하고 다음과 같이 복합레진 (Z-250, 3M ESPE)을 충전하여 광중합하였다. 1 군: 하층판에 복합레진을 충전하고 광중합 한 후, 상층판을 접합하고 레진을 충전하여 광중합을 하였다 (OIL를 남김). 2군: 하층판에 복합레진을 충전하고 팡중합 한 후 acetone에 적신 cotton으로 문질러서 OIL를 제거하고 상층판을 접합하여 복합레진을 충전하고 광중합을 하였다 (OIL를 제거). 3군: 하층판에 복합레진을 충전하고 Mylar strip을 접합하여 공기와의 접촉을 차단한 후 광중합을 하였다. Mylar strip을 제거하고 상층판을 접합 후 복합레진을 충전하여 광중합을 하였다 (OIL형성을 억제). 4군: 하층판에 복합레진을 충전하고 광중합 한 후 glycerin을 OIL표면에 도포하고 다시 광중합하였다. 상층판을 접합하여 복합레진을 충전하고 광중합을 하였다 (OIL를 중합). 5군 (대조군): 하층판과 상층판의 경계에 복합레진층의 계면이 위치하지 않도록 복합레진을 bulk충전하였다 (계면 형성 없이 bulk 충전한 복합레진). 24시간 100% 습도에서 보관 후 상층판과 하층판 사이의 계면 전단결합강도를 측정하고 파절 양상을 관찰하였다. 계면을 통한 중합과정의 확산을 관찰하기 위하여 제조한 광개시제가 들어있지 않은 실험적 복합레진 (Exp_Com)을 몰드에 충전하고 상부에 flowable 복합 레진 (Aelite Flow) 또는 접착레진 (ScotchBond Multipurpose)을 접촉시킨 후 광조사하였다. 몰드내의 미중합된 Exp_Com을 acetone bath 에서 5 분 동안 제거한 후 몰드내에 다시 Aelite Flow를 충전하고 광중합을 시행하였다. 경화된 복합레진 시편의 단면을 관찰하여 ExP_Com 층의 두께를 측정하였다. OIL를 배제하거나 중합시킨 2-4 군은 OIL이 존재하는 1 군과 통계적으로 유의한 결합강도의 차이를 보이지 않았으며, Mylar strip을 이용하여 OIL의 생성을 억제했던 3 군과 glycerin을 도포하여 OIL를 중합시킨 4 군은 계면을 생성하지 않은 대조군인 5 군과도 통계적으로 유의한 차이를 보이지 않았다. 중합과정의 확산에 의해 중합개시제가 포함되지 않은 Exp_Com내에 중합된 층이 생겨난 것을 시각적으로 확인할 수 있었으며, Exp_Com의 중합층 두께는 flowable 레진의 경우 20,95 (0.90) um였고 접착레진의 경우 42.13 (2.09) 였다. This study was aimed to investigate whether an oxygen inhibition layer (OIL) is essential for the interfacial bonding between resin composite layers or not. A composite (Z-250, 3M ESPE) was filled in two layers using two aluminum plate molds with a hole of 3.7 ㎜ diameter. The surface of first layer of cured composite was prepared by one of five methods as followings. thereafter second layer of composite was filled and cured: Group 1 - OIL is allowed to remain on the surface of cured composite; Group 2 - OIL was removed by rubbing with acetone-soaked cotton; Group 3 - formation of the OIL was inhibited using a Mylar strip; Group 4 - OIL was covered with glycerin and light-cured; Group 5 (control) - composite was bulk-filled in a layer. The interfacial shear bond strength between two layers was tested and the fracture modes were observed. To investigate the propagation of polymerization reaction from active area having a photo-initiator to inactive area without the initiator, a flowable composite (Aelite Flow) or an adhesive resin (Adhesive of ScotchBond Multipurpose) was placed over an experimental composite (Exp_Com) which does not include a photoinitiator and light-cured. After sectioning the specimen, the cured thickness of the Exp_Com was measured. The bond strength of group 2, 3 and 4 did not show statistically significant difference with group 1. Groups 3 and 4 were not statistically significant different with control group 5. The cured thicknesses of Exp_Com under the flowable resin and adhesive resin were 20.95 (0.90) um and 42.13 (2.09), respectively.

고에너지 전자빔 투사방법에 의한 2층 VC/Ti-6Al-4V 표면복합재료의 제조와 마모 및 파괴특성

吳俊喆,李昌燮,李聖鶴 대한금속재료학회 2001 대한금속·재료학회지 Vol.39 No.12

This study is concerned with the analysis of microstructure, hardness, wear resistance, and fracture toughnes of two-layered VC/Ti-6Al-4V surface composites fabricated by high energy electron beam irradiation. The mixture of VC powders and CaF_2 flux was deposited on a Ti-6Al-4V substrate, and then electron beam was irradiated on these powder mixture to fabricate a one-layered surface composite. A two-layered surface composite was also fabricated by irradiating electron beam again onto the powder mixture deposited on the one-layered surface composite. The composite layers of 1.2∼1.5 ㎜. in thickness were homogeneously formed without defects, and contained a large amount (25∼40 vol.%) of (Ti, V)C precipitates in the martensitic or V-rich β-Ti matrix. This microstructural modification including the formation of hard carbides and hardened matrices in the surface composite layers improved hardness and wear resistance. Particularly in the two-layered surface composite containing more carbides, the wear resistance was greatly enhanced by seven times higher than that of the Ti-6Al-4V substrate. In-situ observation of fracture process showed that microcracks were initiated at carbides and propagated along these microcracked carbides, and that in the two-layer surface composite, more microcracks were easily formed at carbides than in the one-layed composite, thereby showing lower fracture toughness.

고에너지 전자빔 투사방법으로 제조된 2층 비정질 합금 표면복합재료의 미세조직 연구

이규홍,윤은섭,이성학,김낙준 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.9

This study is concerned with the fabrication of two-layered amorphous/Cu surface composites by high-energy electron-beam irradiation. The mixture of Zr-base amorphous powders and LiF+MgF₂ flux was deposited on a pure Cu substrate, and then electron beam was irradiated on these powder mixture to fabricate a one-layered surface composite. A two-layered surface composite was also fabricated by irradiating electron beam again onto the powder mixture deposited on the one-layered surface composite. The composite layers of 1.6~1.7 mm in thickness were homogeneously formed without defects, and the two-layered composite contained a few fine crystalline phase particles in the amorphous matrix. This fabrication could be achieved by (1) the use of flux which protected the oxidation environments, (2) the second electron-beam irradiation which melted already-formed crystalline particles, and (3) the fast cooling rate of the irradiation method which provided the high amorphous forming ability. Such a development of the fabrication technique of amorphous alloy surface composites presented new applicability of amorphous alloys to structures and components requiring excellent mechanical properties.

Effect of heat treatment on the bending behavior of tri-layered Cu/Al/Cu composite plates

Kim, I.K.,Hong, S.I. Scientific and Technical Press ; Elsevier Science 2013 Materials & design Vol.47 No.-

Bending and fracture behaviors of tri-layered Cu/Al/Cu composite plates were processed by roll-bonding and the effects of work hardening and displacement rate sensitivity during bending on the overall bending behavior and fracture were investigated. As-roll-bonded composite exhibited the extensive load plateau before a relatively rapid load drop. The more localized bending in the as-roll-bonded Cu/Al/Cu clad composite can be attributed to the near-zero work hardening rate in bending. For the Cu/Al/Cu composites annealed at 300<SUP>o</SUP>C and up to 450<SUP>o</SUP>C, the pronounced work hardening during bending tends to distribute the bending deformation uniformly. For the as-roll-bonded Cu/Al/Cu composite, a fatal crack perpendicular to the Cu/Al interface through the bottom Cu layer was formed by the large tensile stress associated with the severely localized bending. A large crack parallel to the interface adjacent to the fatal crack through the bottom Cu layer appeared to have propagated in Al layer, not along the interface between Al and the bottom Cu layer, suggesting the excellent bonding between Al and Cu in the as-roll-bonded Cu/Al/Cu. For annealed clad composites at 500<SUP>o</SUP>C, the localized bending is thought to be caused by the growth of cracks along the interface reaction layer, resulting in the fracture of bottom Cu layer.

Layer-by-Layer 코팅법을 적용한 복합막 제조와 투과성능 평가

전이슬,임지원 한국막학회 2015 멤브레인 Vol.25 No.6

In this study, composite membrane is prepared by Layer-by-Layer method using hydrophobic polymer as a coating material on the polysulfone support. The existence of coating layer on the surface and cross section was confirmed by the scanning electronic microscopy. The flux and rejection of the resulting membranes were characterized using 100 ppm NaCl feed solution. PVSA, PEI, PAA, PSSA, PSSA_MA were used as a coating polymer in this study. The composite membrane prepared by using 8,000 ppm PAA solution (Ion strength = 0.35, Coating time = 3 min) and 10,000 ppm PEI solution (Coating time = 4 min). As a result, PAA-PEI composite membrane showed flux of 101 LMH and salt rejection of 66.7%. The composite membrane showed the comparable performance as good as NE 4040-70 (Flux = 30 LMH, Rejection = 40~70%) model produced by Toray Chemical co. 폴리설폰막 위에 친수성 고분자를 Layer-by-Layer법으로 코팅하여 복합막을 제조하였다. FE-SEM 분석을 통하여복합막 표면과 기공 내 코팅층을 확인하였다. 또한 100 ppm NaCl 용액에 대한 복합막의 투과성능 평가를 실시하였다. 복합막 제조를 위한 코팅 고분자는 PVSA, PEI, PAA, PSSA, PSSA_MA를 사용하였다. 폴리설폰막 표면에 8,000 ppm PAA (이온세기 0.35) 수용액을 3분 동안 코팅한 뒤 10,000 ppm PEI 수용액을 4분 동안 코팅하였다. 그 결과 PAA-PEI 복합막의 투과도는 101 LMH, 제거율은 66.7%로 가장 좋은 투과성능을 나타내었다. PAA-PEI 복합막의 투과성능은 도레이케미칼의 NE 4040-70 (투과도 = 30 LMH, 염 배제율 = 40~70%) 제품과 유사한 성능을 보여주는 우수한 투과 특성을 나타내었다.

Dual-layered nanocomposite substrate membrane based on polysulfone/graphene oxide for mitigating internal concentration polarization in forward osmosis

Lim, Sungil,Park, Myoung Jun,Phuntsho, Sherub,Tijing, Leonard D.,Nisola, Grace M.,Shim, Wang-Geun,Chung, Wook-Jin,Shon, Ho Kyong Elsevier 2017 Polymer Vol.110 No.-

<P><B>Abstract</B></P> <P>A novel thin-film composite (TFC) forward osmosis (FO) membrane with dual-layered substrate membrane was fabricated by a double-blade casting technique using different polysulfone (PSf) concentrations for top (15 wt%) and bottom (7 wt%) substrate layers. Graphene oxide (GO) was incorporated in the substrate layer, and the dual casting approach resulted in a membrane support with a highly porous bottom structure and a dense top skin layer on which the polyamide active layer was effectively formed. The dual-layered TFC PSf/GO membrane (TFC-PSf<SUB>d</SUB>GO) exhibited high water permeability, and ion selectivity was enhanced by the presence of well dispersed hydrophilic GO in the PSf substrate. The TFC-PSf<SUB>d</SUB>GO also exhibited the lowest specific reverse salt flux (<I>J</I> <SUB> <I>s</I> </SUB> <I>/J</I> <SUB> <I>v</I> </SUB> = 0.19 g L<SUP>-1</SUP>) and a more favorable structural parameter (S = 130 μm) compared to GO-free membranes. Using deionized water as feed solution and 1 M NaCl as draw solution (DS), TFC-PSf<SUB>d</SUB>GO had <I>J</I> <SUB> <I>v</I> </SUB> = 33.8 L m<SUP>−2</SUP> h<SUP>−1</SUP> and <I>J</I> <SUB> <I>s</I> </SUB> = 6.9 g<SUP>−2</SUP> h<SUP>−1</SUP> under AL-FS mode, and <I>J</I> <SUB> <I>v</I> </SUB> = 61.5 L m<SUP>−2</SUP>h<SUP>−1</SUP> and <I>J</I> <SUB> <I>s</I> </SUB> = 14.0 g<SUP>−2</SUP> h<SUP>−1</SUP> under AL-DS mode. The potential of TFC-PSf<SUB>d</SUB>GO for commercial application was further evaluated by fabricating it with a fabric backing support (denoted as TFC-PSf<SUB>d</SUB>GO<SUB>f</SUB>). Compared to TFC-PSf<SUB>d</SUB>GO, TFC-PSf<SUB>d</SUB>GO<SUB>f</SUB> exhibited only 14% decline in its water flux. The overall results reveal that, fabrication of TFC substrate membrane via dual-blade casting approach along with GO incorporation produced high-performance TFC FO membranes which likely reduced the internal concentration polarization effects.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The dual-layered PSf/GO membrane was developed to mitigate the ICP effect. </LI> <LI> The dual-layered PSf substrates exhibited higher porosity and water permeability. </LI> <LI> Incorporation of GO further improved hydrophilicity of membrane substrate. </LI> <LI> The dual-layered PSf/GO membrane demonstrated the best membrane performances. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Structure and Mechanical Properties of a Layered Composite Based on Fe–Cr–V Alloy and High-Nitrogen High-Chromium Steel After Hot Pressing and Annealing

V. M. Khatkevich,S. O. Rogachev,S. A. Nikulin,E. N. Tokmakova 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

A hot pressing method was used to obtain a layered composite consisting of alternating layers of AISI 439 type steel witha high nitrogen content (0.8%) and Fe-20% Cr-5%V alloy with a low nitrogen content (less than 0.02%). Annealing of thecomposite at T = 700–850 °C after hot pressing leads to diffusion of nitrogen from the nitrided AISI 439 layers into theFe–Cr–V layers, the formation of diffusion zones containing dispersed vanadium nitrides in the Fe–Cr–V layers and theformation of diffusion zones with a low nitrogen content in the AISI 439 layers. A tendency towards a decrease in the sizesof the vanadium nitride particles with decreasing annealing temperature was revealed. Annealing at T = 750 °C increasesthe plastic characteristics and reduces the strength characteristics of the composite compared to the state after hot pressing. The presence of dispersed vanadium nitrides precipitated in the composite structure during annealing increases the strengthof the composite by 15%.

Bond Strength Evaluations of Composite Pavement Using Accelerated Pavement Testing and Experimental Construction

Han Jin Oh,Jun Young Park,Hyung Bae Kim,Won Kyong Jung 한국도로학회 2018 한국도로학회 학술대회 발표논문 초록집 Vol.2018 No.05

Composite pavements are constructed by placing a high functional asphalt surface layer on a high performance concrete rigid base layer and provide a more durable, high functional surface to road users. Service life of composite pavements is dependent on the bonding performance of the lower rigid base and the flexible surface layer. Accordingly, it is necessary to place an impermeability layer between the functional surface layer and the rigid base to enhance bonding performance and to prevent moisture penetration into the rigid base and deterioration of pavement. In order to use optimal composite pavement sections, two types were applied to impermeability layer: highly impermeable water-tight SMA and mastic asphalt currently in use. APT (Accelerated Pavement Testing) and experimental construction were carried out to evaluate bond strengths between the rigid base and the impermeability layer depending on the type of impermeability layers. Composite pavement sections for the APT had a 22 cm concrete rigid base layer and a 5cm functional surface, as well as either 5cm of SMA impermeability layer and 5cm of mastic layer. After applying around 8,574,000 ESALs, pull-off test was conducted, which showed that the mastic section outperformed the SMA section. In the experimental construction, three types of rigid base layers, JCP (Jointed Concrete Pavement), CRCP (Continuously Reinforced Concrete Pavement), and RCCP (Roller Compacted Concrete Pavement), were used for composite pavement sections, and as in the APT, two types of impermeability layers, SMA and mastic, were used per rigid base layer of new and deteriorated concrete pavement. Therefore, seven composite pavement sections in total were constructed. We measured the bond strength over one year or so following the construction of these composite pavement sections and found that regardless of the type of rigid base layer and whether it was new or not, those sections with a mastic impermeability layer had high bond strengths.

Ultrathin gutter layer for high-performance thin-film composite membranes for CO₂ separation

Yoo, Myung Jin,Kim, Kyung Hyun,Lee, Jun Hyeok,Kim, Tae Woo,Chung, Chin Wook,Cho, Young Hoon,Park, Ho Bum Elsevier 2018 Journal of membrane science Vol.566 No.-

<P><B>Abstract</B></P> <P>Ultrathin film composite (TFC) membranes with selective layers less than 100 nm thick are highly desired to maximize the permeance of gas separation membranes for high energy efficiency. For membranes with ultrathin selective layers, a gutter layer is usually required to prevent pore penetration in the selective layers. Also, according to a recent model, the introduction of a gutter layer strongly improves TFC membrane performance by increasing the overall membrane performance up to an order of magnitude. Unfortunately, this improvement comes with an undesired decrease in selectivity unless the gutter layer is properly designed. This study found that the gutter layer permeability should be five- to tenfold that of the selective layer to minimize the decrease in selectivity. However, the most commonly used material for the gutter layer, polydimethylsiloxane, does not meet the requirements for high-performance membrane materials. Thus, here we report a gutter material with CO<SUB>2</SUB> permeance sixfold that of polydimethylsiloxane, and prepare a TFC membrane with ultrathin gutter (75 nm) and selective layers (70 nm) for CO<SUB>2</SUB>/N<SUB>2</SUB> separation. This work represents a guideline for developing next-generation TFC membranes and provides a comprehensive understanding of the impact of the gutter layer.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A gutter layer with over sixfold enhanced CO<SUB>2</SUB> permeance was prepared. </LI> <LI> Inductively coupled plasma was used for hydrophilic treatment with minimized damage. </LI> <LI> Ultrathin (< 100 nm) selective layer was successfully coated on the gutter layer. </LI> <LI> The as-prepared membrane exhibited 1455 GPU of CO<SUB>2</SUB> permeance with CO<SUB>2</SUB>/N<SUB>2</SUB> 68. </LI> <LI> Long-term stability was confirmed upon 10,000 min operation. </LI> </UL> </P>

Al/SiCp 복합재료의 마모거동에 미치는 MML의 영향

김영식,김균택 한국트라이볼로지학회 2009 한국윤활학회지(윤활학회지) Vol.25 No.1

Al-based composites reinforced with SiC particulate were fabricated using a thermal spray process, and dry sliding wear behavior of the composites was investigated. Pre-mixed Al and SiC powders were sprayed on an Al6061 substrate by flame spraying, and dry sliding wear test were performed under various sliding speed and applied load conditions against Al2O3 ball. Wear behavior of the composites was studied by using scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). And build-up mechanism of MML on the worn surface of the composites was examined. It was revealed that these MML was formed of debris from the contact surface of the composites and effected to wear behavior of the composites protecting the contact surface of the composites.