• Journal of the Korean institute of surface engineering
• /
• v.29 no.4
• /
• pp.261-267
• /
• 1996

The characteristics and adhesion strength of TiN layer deposited by D. C. magnetron sputtering were investigated. Three types of TiN layers were deposited on STS304 stainless steel. Scratch tests were performed to determine the effect of deposition temperature, the thickness of coated TiN layer and the titanium inter-layer on the adhesion strength. TiN multilayer with titanium inter-layer showed the highest critical load in the deposition temperature range of $25^{\circ}C$ to $300^{\circ}C$. Adhesion strength of TiN multilayer with titanium inter-layer was raised from 15N to 20N by raising deposition temperature from $25^{\circ}C$ to $400^{\circ}C$. Adhesion strength was raised from 18N to 38N by increasing the thickness of outer layer of TiN multilayer from 2.1 $\mu\textrm{m}$ to 9.5 $\mu\textrm{m}$.

• Journal of the Korean Society for Heat Treatment
• /
• v.14 no.2
• /
• pp.81-88
• /
• 2001

The effects of post-oxidation and sulfnitriding treatments on the phase transformation in the nitrided case of tool steels have been studied. Dense and compact $Fe_3O_4$ layer was formed at the outer surface of nitride compound layer by post-oxidation treatment and multi layer of iron sulfide(FeS) was formed in the compound layer by sulfnitriding treatment. The surface hardness decreased because of formation of the soft oxide or sulfide at the nitride surface. Diffusion layer of nitride case was not affected by post-oxidation treatment or sulfnitriding treatment of nitrided alloy tool steels.

• Journal of Korean Vacuum Science & Technology
• /
• v.3 no.1
• /
• pp.49-53
• /
• 1999

We have studied the field emission characteristics of diamond-like-carbon (DLC) films deposited by a layer-by-layer technique using plasma enhanced chemical vapor deposition, in which the deposition of a thin layer of DLC and a CH4 plasma exposure on its surface were carried out alternatively. The hydrogen-free DLC can be deposited by CH4 plasma exposure for 140 sec on a 5 nm DLC layer. N2 gas-phase doping in the CH4 plasma was also carried out to reduce the work function of the DLC. The optimum [N2]/[CH4] flow rate ratio was found to be 9% for the efficient electron emission, at which the onset-field was 7.2 V/$\mu\textrm{m}$. It was found that the hydrogen-free DLC has a stable electron emitting property.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.28A no.5
• /
• pp.380-386
• /
• 1991

Hydrogen plasma-assisted epitaxial(PAE) growth of GaAs/Si and GaAs/Ge/Si with Ge buffer layer has been investigated. By means of photoluminescence, Nomarski microscopu, and $\alpha$-step, it could be known that GaAs on Si with Ge buffer layer has better crystalline quality than GaAs on Si without Ge buffer layer. The stoichiometry of GaAs layer on Si was confirmed by the depth profile of Auger electron spectroscope (AES). Also the native oxide(SiO$_2$) layer on Si substrate was plama-etched and the removal of the oxide layer was confirmed by AES. Photoluminescence peak wavelength of GaAs/Ge/Si with Ge buffer of 1\ulcorner thickness and GaAs growth rate of 160$\AA$/min was 8700$\AA$and FWHM was 12$\AA$.

• Transactions on Electrical and Electronic Materials
• /
• v.1 no.4
• /
• pp.7-10
• /
• 2000

Bi$_2$Sr$_2$CuI$\_$x/(Bi(2001)) thin films are fabricated by atomic layer by layer deposition using ion beam sputtering(IBS) method. During the deposition , 10 %-ozone/oxygen mixture gas of typical 25.0$\times$10$\^$-5/ Torr is applied with ultraviolet light irradiation for oxidation. XRD and RHEED investigations reveal out that a buffer layer with some different compositions is formed at the early deposition stage of less then 10 units cell and then c-axis oriented Bi(2201) is grown.

• Journal of Welding and Joining
• /
• v.7 no.4
• /
• pp.46-55
• /
• 1989

Zirconia coatings are performed by the plasma spraying on the substrate of Al-Si alloy. In case of plasma sprayed ceramic coatings, it is important to control properly residual stress occurred during cooling process. Residual stress in coating layer varies with sprayed conditions and is influenced greatly by the coating layer thickness. Surface residual stress due to coating layer thickness is measured by X-ray diffraction method and the residual stress in coating layer is estimated by the deflection of coating layer when the restraint force in substrate was removed. When zirconia was coated on the substrate, tensile residual stress remains on zirconia coated surface layer. The tensile stress is increased to 0.35mm thickness and after 0.45mm thickness it is decreased abrouptly. A thick bond and composite coating reduce the zirconia surface stress and composite coating controls effectively the thick zirconia surface stress.

• Fibers and Polymers
• /
• v.4 no.2
• /
• pp.49-53
• /
• 2003

Polyurethane (PU) layer and copolymer consisted of the different molecular weights (1000 and 2000 g/mol) of poly(propylene glycol) (PPG) were prepared. The damping and mechanical properties of these materials were compared with PU 1000 made by PPG having the molecular weight of 1000 g/mol. The optimum composition of PU2000 used for PU layer and copolymer was diphenylmethane diioscynate (MDI)/propylene glycol (PPG)/butanediol (BD) (1/0.3/0.7) based on the damping and mechanical properties. The damping peak of PU copolymer was higher than those of PU layer and PUI 1000 in low temperature range (-30- $10^{\circ}C$). For application in noise reduction, the transmission loss of the mechanical vibration through solid structure was measured. PU layer and copolymer were used as a damping layer. The transmission loss of PU copolymer was more effective than those of PU layer and PU 1000 in the experimental frequency range.

• Journal of the Korean Applied Science and Technology
• /
• v.19 no.4
• /
• pp.297-301
• /
• 2002

We investigated the effect of electron injection layer on the performance of organic light emitting devices (OLEDs). As an electron injection layer, the quinolate metal complexes were used. We optimized the device efficiency by varying the thickness of the quinolate metal complexes layer. The device with 1 nm of the quinolate metal complexes layer showed significant enhancement of the device performance and device lifetime. We also compared the effect of 8-hydroxyquinolinolatolithium (Liq) with that of bis(8-quinolinolato)-zinc ($Znq_{2}$) and 8-hydroxyquinolinolatosodium (Naq) as an electron injection layer. As a result, Liq is considered as a better materials for the electron injection layer than $Znq_{2}$ and Naq.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.3
• /
• pp.261-267
• /
• 2002

The integral boundary layer equation for the air side and the diffusion equation for the frost layer are numerically analyzed in order to predict the behavior of frost layer growth. The thickness and density of the frost layer obtained from the present study agree well with those of previous numerical results and experimental data with a maximum error of 13%. The characteristics of heat and mass transfer within the frost layer and the frost layer growth along the flow direction are investigated by performing numerical analysis. The effects of operating conditions on the frost layer growth are also examined.

• Journal of Magnetics
• /
• v.14 no.4
• /
• pp.168-171
• /
• 2009

We propose a new type of spin torque nano-oscillator structure with an exchange- biased free rotating layer. The proposed spin torque nano-oscillator consists of a fixed layer and a free rotating layer with an additional anti-ferromagnetic layer, which leads to an exchange bias in the free rotating layer. The spin dynamics of the exchange-biased free rotating layer can be described as an additional exchange field because the exchange bias manifests itself by the existance of a finite exchange bias field. The exchange bias field plays a similar role to that of a finite external field. Hence, microwave generation can be achieved without an external field in the proposed structure.