• Journal of the Korean Society for Heat Treatment
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• v.13 no.5
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• pp.355-359
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• 2000

Ion beam assisted deposition system was used to deposit CNx coatings with various thickness on the substrates of high-frequency induction hardened steels. Rolling contact fatigue tests were performed using Polymet RCF-1 machine with a constant supply of lubricant. Rolling contact fatigue life was substantially different in the steels with various thickness of CNx coatings. The optimum thickness of CNx coating was found to be $8.9{\mu}m$, showing the longest fatigue life, mainly caused by higher resistance to initiation of cracks and protective overcoat remaining to the surface failure during rolling contact fatigue. Cracks were initiated in the substrates under the surface of wear track and propagated to the surface, which eventually resulted in the failure. The reduction of fatigue life observed in the specimen with elimination of CNx coating during rolling contact fatigue was explained by the substrates deformation.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.30-36
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• 1998

The plasma-spray technique is currently the most frequently used method to produce calcium phosphate coatings. Hydroxyapatite(HAp), one form of calcium phosphate, is preferred by its ability to form a direct bond with living bone, resulting in improvements of implant fixation and faster bone healing. Recently, concerns have been raised regarding the viable use and long-term stability of plasma-spray HAp coatings due to its nature of comparatively thick, porous, and poor bonding strength to metal implants. Thin layers (maximum of few microns) of calcium phosphate were formed by an e-beam evaporation with and without ion bombardments. The Ca/P ration of film was controlled by either using the evaporants having the different ration of Ca/P with addition of CaO, or adjusting the ion beam assist current. The Ca/P ration had great effects on the structure formation after heat treatment and the dissolution bahavior. The calcium phosphate films produced by IBAD exhibited high adhesion strength.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.105-112
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• 2002

We studied the optical and structural properties of conventional and ion-beam-assisted-deposition (IBAD) Nb$_2$O$_{5}$ films which were evaporated by an electron beam gun. The vacuum-to-air spectral shift and the cross sectional SEM images of the Nb$_2$O$_{5}$ films were investigated. The results show that the IBAD Nb$_2$O$_{5}$ films have a higher packing density than the conventional Nb$_2$O$_{5}$ films. The average refractive index of IBAD Nb$_2$O$_{5}$ films was increased, while the extinction coefficient was decreased compared with the conventional films. As the oxygen flow was increased, the average refractive index and extinction coefficient of the conventional and IBAD films decreased. Both the conventional and IBAD Nb$_2$O$_{5}$ films showed inhomogeneity in refractive index, and the degree of inhomogeneity of the IBAD Nb$_2$O$_{5}$ films became larger as the ion current density was increased. All Nb$_2$O$_{5}$ films were found to be amorphous by x-ray diffraction (XRD) analysis, and hence the crystal structure of Nb$_2$O$_{5}$ films was not changed by IBAD.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.117-117
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• 2000

높은 광학적 투과성과 전기전도성을 갖는 ITO film은 solar cell같은 optoelectronic device나 휴대용 소형 TV, flat panel display 등의 투명전극으로 그 응용 분야가 광범위하여 많은 연구가 수행되어져 왔다. 기판으로서 유리를 사용할 때 생기는 활용범위 제한을 극복하고자 최근 유기물 위에 증착이 가능한 저온 증착방법에 대한 연구가 활발히 이루어지고 있다. 그 가운데 이온빔과 같은 energetic한 beam을 이용한 박막의 제조는 기판을 플라즈마 발생지역으로부터 분리시켜 이온빔의 flux 및 에너지, 입사각 등의 자유로운 조절을 통해 상온에서도 우수한 성질의 박막형성 가능성이 제시되어 지고 있다. ITO박막을 형성하는 방법 중 스프레이법이나 CVD법과 같은 화학적 증착방법은 증착시 350-50$0^{\circ}C$의 고온이 필요하고 현재 가장 많이 응용되어 지고 있는 sputter법은 15$0^{\circ}C$정도의 가열이 필요하므로 앞으로 응용가능성이 매우 커서 많은 연구가 진행중인 플라스틱과 아크릴 같은 flexible 한 기판위 증착에 적용이 불가능하다. 본 실험에서는 IBAD(Ion Beam Assisted Deposition)법을 이용하여 저온 ITO film을 유리와 유기막위에 증착하는 연구를 수행하였다. 유기막위에 증착된 ITO는 보다 가볍고 충격에 강하고 유리에 못지 않은 투과성을 가지고 있으나 현재 film의 quality 향상에 대한 요구가 증대되어 지고 있는 실정이다. 따라서, 본 실험에서는 dual oxygen ion gun의 조건변화에 따른 ITO film의 특성변화를 관찰하였다. 고정된 증？율에 한 개 ion gun에 ion flux를 고정시킨 후 또 다른 ion gun에서 발생하는 oxygen radical의 영향을 조사하였으며 oxygen radical의 rf power에 따른 변화는 OES(Optical emission spectroscopy)를 사용하였다. 너무 적은 oxygen ion beam flux나 oxygen radical은 film의 전도도 및 투과도를 저하시켰고 반면 너무 과도한 flux의 증가 시는 전도도는 감소하였고 투과도는 증가하는 경향을 보였다. 기판에 도달하는 oxygen ion flux는 faraday cup을 이용하여 측정하였으며 증착된 ITO film은 XPS, UV-spectrometer, 4-point probe를 이용하여 분석하였다.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.204-208
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• 2002

We investigate the dependence of indium tin oxide (ITO) thin films on the mixing ratio of Ar:O$_2$ produced by an ion-gun and $O_2$ injected inside the divergence angle of the ion-beam to optimize their sheet resistance and transmittance. The substrate is placed outside the divergence angle, and the films are grown by ion mixing with ITO evaporated at room temperature. From the XRD measurement ITO films are found to be amorphous. ITO thin films show the highest transmittance of 85% at 3$\times$10$^{-5}$ Torr of 0$_2$ and Ae:O$_2$ ratio of 40:60, and the smallest sheet resistance of 132 $\Omega$/$\square$at 1$\times$10$^{-5}$ Torr of $O_2$ and As:O$_2$ ratio of 40:60.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.147-151
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• 2000

We deposited the ion assisted ${Ta_2}{O_5}$ films and conventional thermal evaporated ${Ta_2}{O_5}$ films by using electron beam gun, and measured the optical properties and mechanical properties of the fabricated films according to the evaporation conditions. In the case of the TazOs films by oxygen ion assisted deposition with the anode voltage of 120 V, and current density of $50~500\muA/cm^2$, the refractive index exhibited 2.15 which was higher than the conventionally deposited film index 1.94 and the tensile stress exhibited $5.0\times10^8 dyne/cm^2$ which was lower than $7.0\times10^8 dyne/cm^2$. This properties coincided with the optical and mechanical properties of the films deposited at the elevated substrate temperature of $230^{\circ}C$. In the case of the argon ion assisted films the tensile stress was decreased but the absorption existed at the short wavelength in the visible spectral region. And all the fabricated films were found to be amorphous by the X-ray diffraction analysis. lysis.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.27-27
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• 1998

진공기술의 응용과 진공환경의 이용은 더 이상 논하지 않더라도 산업 전반에 그 충요성이 점점 더 커가고 있다. 이러한 여건에도 불구하고 진공율 이용하는 system 개밟의 국산화는 수 입하는 system으$\mid$ 수에 비하여 절대적으로 부족하며, 또한 개발하는 system의 자동화는 거의 이 루어지지 않고 있으며, 자동화된 진공판련 system은 거의 대부분 수입에 의흔하고 있다. 실험 실 규모에서부터 System올 하나하나 개밭하고, 이톨 자동화하는 노력과 일이 진행됨다면 산업 응용에 있어서도 자연스럽게 자동화된 system으$\mid$ 개발이 이루어 질 것이다 .. system 자동화는 상 품수명의 단축과 이에 따른 다품종 소량을 요구하는 시장수요에 대응하고, 인력절감과 고풀짙 화로 생산성 향상의 요구에 대응하기 위하여 필요하다. 본 연 구에 서 는 e-beam evaporator로 evaporation하면 서 ion beam으로 assist하여 thin film율 제 작하는 IBAD vacuum system율 싫 계 및 제 작하고[1,2], PLC[3,떼톨 이 용하여 system 자동화톨 하였다 .. thin film 제작 process는 먼저 기본 진공상태로 만뚫고 난 뒤, e-beam evaporator로 e evaporation하면서 ion beam source로 assist하여 substrate 011 thin film율 제조한다 226;. thin film올 제 조하면서 thickness monitor로 sample의 thickness rate톨 control 하고, sample의 균얼성과 밀착 성을 고려하여 substrate톨 rotation 및 heating 할 수 있도록 싫계, 제작하였다. 양질의 박막올 제조하기 위해서 진공환경이 좋은 상태로 제공되어야 한다. 이톨 위하여 oil free operation 0 I 가 능한 dry pump와 turbo molecular pump로 고진공 배기 하였다. 진공도의 흑점은 thermal effect 툴 고려하여 cold cathode ion gauge률 사용하였고, intro chamber와 main chamber 사이에는 g gate valve톨 설치하여 벌도로 운용되도록 하였다. 이러한 process를 박막의 두께, 진공도, 시 간, 온도, 공정 동의 조건올 기훈으로 자동화한 것이다. 또한 정전과 단수에 대한 interlock 기능 도 고려하였다.하였다.

• Korean Journal of Optics and Photonics
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• v.8 no.1
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• pp.37-41
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• 1997

The optical property, the environmental stability and the crystallization of ZnS thin films prepared by ion-assisted deposition (IAD) were investigated and compared with those of conventional electron-beam deposited thin films. The humidity(R.H. 85%) test and the thermal(15$0^{\circ}C$) show that the IAD films have relatively higher refractive index, smaller extinction coefficient and environmentally more stable than the conventional films. It is believed to originate from the reduced adsorption of moisture which reflect the increased packing density and the improved microstructure by ion bombardment. XRD experiments also confirm that conventionally grown films have an amorphous in comparison with the crystalline structured IAD films.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.527-532
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• 2005

Ionic polymer metal composites (IPMC) are soft polymeric smart materials having large displacement at low voltage in air and water. The polymeric electrolyte actuator consists of a thin and porous membrane and metal electrodes plated on both faces, in impregnation electro-plating method. The response and actuation of actuator are governed. Among many factors governing the activation and response of IPMC actuator, the surface electrode plays an important role. In this study, the well-designed modification of electrode surface was carried out in order to improve the chemical stability well as electromechanical characteristics of the IPMC actuator. We employed Ion Beam Assisted Deposition (IBAD) method to prepare the topologically homogeneous thin surface electrode. After roughing the surface of Nafion membrane in order to get a larger surface area, the IPMC was prepared by impregnation for electro-plating and re- coating on the surface through traditional chemical deposition, followed by an additional surface treatment with high conductive metals with IBAD. It was observed that our IPMC specimen shows the enhanced surface electrical properties as well as the improved actuation and response characteristics under applied electric field.

• Korean Journal of Optics and Photonics
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• v.4 no.3
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• pp.260-265
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• 1993

An in-situ stress measurement interferometer is constructed and used to measure the intrinsic stress in Ti$O_2$ thin films during their growth by ion-assisted deposition. It is found that the stress increases with the momentum transferred by the ion beam to the growing film and is fairly well agreed with Windischmann's model. The variation of the stress with thickness is qualitatively explained in terms of the balance between the compressive stress produced by the ion beam and the surface diffusion determined by the surface temperature.