• Journal of Electrochemical Science and Technology
• /
• v.9 no.1
• /
• pp.1-8
• /
• 2018

The effect of mixing ratio on the corrosion protection of carbon steel coated by a film composed of poly(vinylidene) fluoride (PVDF) and poly(methyl methacrylate) (PMMA) was examined using electrochemical impedance spectroscopy. Surface crystallization behavior and thermal properties of the PVDF/PMMA coated carbon steel were evaluated using polarized optical microscopy and differential scanning calorimetry, respectively. A Maltese cross-pattern spherulite crystal was observed in the PVDF/PMMA coating film, which became more apparent with increasing PVDF content. The highest corrosion protection performance was achieved with 60 wt.% PVDF-coated carbon steel, and delamination and corrosion reactions were observed for 20 wt.% PVDF-coated carbon steel. Further, corrosion protection performance with an amorphous/crystal mixture (PVDF/PMMA, 60/40 (w/w)) was better than those observed in the amorphous domain and the perfect-crystal domain of the PVDF/PMMA blended coating system.

• Journal of the Korean Vacuum Society
• /
• v.22 no.1
• /
• pp.31-36
• /
• 2013

For the simplification of doping process in amorphous carbon film, arsenic (As) ions were implanted on the nucleated silicon wafer before the growth process. Then amorphous carbon films were grown at the condition of $CH_4/H_2=5%$ by microwave plasma chemical vapour deposition. Because the implanted seeds were grown at the high temperature and the implanted ions were spread, it was possible to reduce the process steps by leaving out the annealing process. When the implanted amorphous carbon films were electrically characterized in diode configuration, field emission current of $0.1mA/cm^2$ was obtained at the applied electric field of about $2.5V/{\mu}m$. The results show that the implanted As ions were sufficiently doped by the self-annealing process by using the growth after implantation.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.381.2-381.2
• /
• 2014

In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.310-310
• /
• 2011

Morphological evolution of amorphous carbon film is investigated by molecular dynamics simulation. Here, energetic carbon atoms (75 eV) are deposited on the diamond (001) substrate to find effect of incidence angles. At normal and near-normal incidences ($0^{\circ}{\sim}30^{\circ}$) atomically smooth surfaces are observed during their growth. However, rough surfaces emerge and develop into a ripple structure at grazing incidences ($60^{\circ}{\sim}70^{\circ}$). The different growth modes according to the incidence angles can be described by impact-induced displacements of atoms. Downhill transport along any sloped surfaces is predominant for the case of normal incidence. As the incidence angles become grazing, uphill transport is allowed along the surfaces, which have smaller slopes than incidence angle, so the surface features can be amplified. Impact-induced transport and self-shadowing effect can be responsible to the initial growth of seeding structures at a grazing incidence, which would be grown up as tilted columnar structures in further depositions.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.484-487
• /
• 2001

Amorphous carbon thin films were deposited using laser ablation technique on Si(100) substrates at different temperatures. In this study, effects of the substrate temperature on the properties of amorphous carbor, films were systematically investigated. The surface morphologic and structural properties of the films were studied by scanning electron microscopy (SEM) and raman spectroscope, respectively. With increasing of the substrate temperature, the surface morphologies were changed significantly. Moreover the intensity ratio of D-band and G-band and the full width at half maximum of these bands were dependent on substrate temperatures.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.335-335
• /
• 2011

Instability of a thin film attached to a compliant substrate often leads to emergence of exquisite wrinkle patterns with length scales that depend on the system geometry and applied stresses. However, the patterns that are created using the current techniques in polymer surface engineering, generally have low aspect ratio of undulation amplitude to wavelength, thus, limiting their application. Here, we present a novel and effective method that enables us to create wrinkles with a desired wavelength and high aspect ratio of amplitude over wavelength as large as to 2.5:1. First, we create buckle patterns with high aspect ratio of amplitude to wavelength by deposition of an amorphous carbon film on a surface of a soft polymer poly(dimethylsiloxane) (PDMS). Amorphous carbon films are used as a protective layer in structural systems and biomedical components, due to their low friction coefficient, strong wear resistance against, and high elastic modulus and hardness. The deposited carbon layer is generally under high residual compressive stresses (~1 GPa), making it susceptible to buckle delamination on a hard substrate (e.g. silicon or glass) and to wrinkle on a flexible or soft substrate. Then, we employ glancing angle deposition (GLAD) for deposition of a high aspect ratio patterns with amorphous carbon coating on a PDMS surface. Using this method, pattern amplitudes of several nm to submicron size can be achieved by varying the carbon deposition time, allowing us to harness patterned polymers substrates for variety of application. Specifically, we demonstrate a potential application of the high aspect wrinkles for changing the surface structures with low surface energy materials of amorphous carbon coatings, increasing the water wettability.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.434-434
• /
• 2011

Electrochemical method have been employed in this work to modify the chemical vapour deposited nitrogen doped hydrogen amorphous diamond-like carbon (N-DLC) film to fabricate nickel and copper nano particle modified N-DLC electrodes. The electrochemical behaviour of the metal nano particle modified N-DLC electrodes have been characterized at the presence of glucose in electrolyte. Meanwhile, the N-DLC film structure and the morphology of metal nano particles on the N-DLC surface have been investigated using micro-Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. The nickel nano particle modified N-DLC electrode exhibits a high catalytic activity and low background current, while the advantage of copper modified N-DLC electrode is drawn back by copper oxidizations at anodic potentials. The results show that metal nano particle modification of N-DLC surface could be a promising method for controlling the electrochemical properties of N-DLC electrodes.

• Journal of the Korean Vacuum Society
• /
• v.16 no.2
• /
• pp.122-127
• /
• 2007

In this research, amophous carbon films (a-C, a-C:H, a-C:N) were synthesized by closed-field unbalanced magnetron (CFUBM) sputtering using graphite target. We also fabricated amorphous carbon films with applying negative DC bias voltage of 200 V in during the deposition in working pressure. Also, a-C:H and a-C:N films was synthesized by adding acethylene($C_{2}H_{2}$) and nitrogen(N) gases of 4 and 3 sccm into Ar pressure. The a-C:H film synthesized at -200 V exhibited the maxumum hardness of 26.3 GPa, the smooth surface of 0.1 nm and the good adhesion of 30.5 N. And a-C:N film synthesized at -200 V exhibited at -200 V exhibited the best adhesion of 32 N. This paper examined the effect of $C_{2}H_{2}$ gas, $N_{2}$ gas and negative DC bias voltage as the parameter for improving the physical properties and the relation between structral and physical properties of carbon films.

• Journal of the Korean Vacuum Society
• /
• v.20 no.5
• /
• pp.333-338
• /
• 2011

In this work, we have fabricated the amorphous carbon (a-C:H) thin film by using unbalanced magnetron sputtering method with the magnetron source of inside/outside electromagnetic coils as the protective coating materials. We have investigated the tribological properties of amorphous carbon films prepared with various electromagnetic coil currents for the change of the plasma density, such as hardness, friction coefficient, adhesion, and surface roughness. Raman and HRTEM were used to study the microstructure of carbon films. In the result, the hardness and adhesion properties of a-C:H films were improved with increasing electromagnetic coil current due to the increase of the plasma density to the substrate. Thus, these results can be explained by the increase of $sp^2$ bonding and cluster number in the amorphous carbon film, related to the improved bombardment around substrate and the increased substrate temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.05a
• /
• pp.130-132
• /
• 2006

In this paper, the author describes a-C films grown in pure methane plasma without any diluent gas by using RF plasma-enhanced CVD, and the variations in their structural features and surface morphologies are examined as a function of substrate temperature. Raman spectroscopy and scanning electron microscopy were performed to characterize the properties of the film.