• Transactions of Materials Processing
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• v.33 no.5
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• pp.330-340
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• 2024

The martensitic Ni-Ti shape memory alloys(SMA) can achieve a two-way shape memory effect (TWSME) through thermomechanical training/cycling. In this study, the surface of Ni-Ti SMA sheets was treated by depositing a certain number of titanium (Ti) powder layers using a selective laser meling (SLM) process to enhance TWSME. The results showed that a unique TWSME of approximately 12% with good stability was achieved after 100 training cycles when the optimum number of five Ti layers was deposited. A larger HAZ and lower cooling rate pushed more Ti particles into the grains rather than the grain boundaries, providing more time for Ti to react with NiTi to form Ti-rich intergranular Ti2Ni(Ox) precipitates. This resulted in further hindering of dislocation movement within the grains and the generation of internal stress fields required for attaining a larger TWSME. With an increase in the number of Ti-deposited layers, there was no noticeable reduction in the one-way shape memory effect (OWSME) through the initial cycling. This was due to the high residual tensile stress caused by the lower thermal expansion of the Ti layer compared to the Ni-Ti sheet.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.6
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• pp.235-239
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• 2011

TiCrN layers (Ti : Cr = 20 : 80 and 5 : 95 wt%) were deposited on Inconel 617 and the effect of TiCrN coating on the high temperature stability of Inconel 617 up to $1000^{\circ}C$ was examined. XRD analysis and microstructural observation showed that vigorous and inhomogenous Cr diffusion to the surface was suppressed by TiCrN layer compare to the uncoated Inconel 617. This led to a distinctive enhancement in thermal oxidation resistance of Inconel 617.

• Journal of Surface Science and Engineering
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• v.45 no.3
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• pp.106-110
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• 2012

Oblique angle deposition (OAD) is a physical vapor deposition where incident vapor flux arrives at non-normal angles. It has been known that tilting the substrate changes the properties of the film, which is thought to be a result of morphological change of the film. In this study, OAD has been applied to prepare single and multilayer TiN films by cathodic arc deposition. TiN films have been deposited on cold-rolled steel sheets and stainless steel sheet. The deposition angle as well as substrate temperature and substrate bias was changed to investigate their effects on the properties of TiN films. TiN films were analyzed by color difference meter, scanning electron microscopy, nanoindenter and x-ray diffraction. The color of TiN films was not much changed according to the deposition conditions. The slanted and zigzag structures were observed from the single and multilayer films. The relation between substrate tilting angle (${\alpha}$) and the growth column angle (${\beta}$) followed the equation of $tan{\alpha}=2tan{\beta}$. The indentation hardness of TiN films deposited by OAD was low compared with the ones prepared at normal angle. However, it has been found that $H^3/E^2$ ratio of 3-layer TiN films prepared at OAD condition was a little higher than the ones prepared at normal angle, which can confirm the robustness of prepared films.

• Journal of Surface Science and Engineering
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• v.38 no.2
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• pp.79-82
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• 2005

This study investigated the effect of nitriding on the hardness and adhesion properties of $TiB_2$ coatings. Inductively coupled plasma (ICP) was used for both nitriding and deposition. By applying ICP, H13 steel was nitrided at a high rate of $50\;{\mu}m/hr$. After nitriding, a Fe4N compound layer or a diffusion layer was formed according to the hydrogen/nitrogen ratio. Both layers could improve the load-bearing capacity of the substrate by increasing the substrate hardness. The adhesion of the $TiB_2$ coatings increased to $\~30N$ after nitriding, but the hardness of the coating was lowered to 20-30 GPa. However, the adhesion of the $TiB_2$ coatings with a high hardness (>60 GPa) could not be improved substantially by nitriding due to the large difference in hardness between the coating and the substrate. The grain size of the $TiB_2$ coating was larger on the nitrided substrates, resulting in a decrease in the hardness of the coating.

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.63-66
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• 2003

It is experimentally shown that a $TiO_2$ film on Si(111) substrate was prepared by using the technique of D.C. reaction sputter deposition with $Ar^{+}$ ion beam bombardment, and a layer-like structure was observed from the depth profile of the interface between $TiO_2$ film and Si substrate with Scanning Electron Microscopy and Electron Probe. It was also surprisingly discovered that Ti atoms could be detected at about 9 $\mu$m depth. The $TiO_2$-Si interface bombarded by $Ar^{+}$ ion beams revealed multi-layer structures, a mechanism might be caused by defect diffusion, impurity and matrix relocation. Multi-relocations of impurity and matrix atoms were as a result of profile broadening of the $TiO_2$-Si interface, and the spread due to matrix relocation in this system is shown to exceed much more the spread due to impurity relocation.

• Korean Journal of Materials Research
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• v.22 no.7
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• pp.379-383
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• 2012

$TiO_2$ thin films consisting of positively charged poly(diallyldimethylammonium chloride)(PDDA) and negatively charged titanium(IV) bis(ammonium lactato) dihydroxide(TALH) were successfully fabricated on glass beads by a layer-by-layer(LBL) self-assembly method. The glass beads used here showed a positive charge in an acid range and negative charge in an alkaline range. The glass beads coated with the coating sequence of(PDDA/TALH)n showed a change in the surface morphology as a function of the number of bilayers. When the number of bilayers(n) of the(PDDA/TALH) thin film was 20, Ti element was observed on the surface of the coated glass beads. The thin films coated onto the glass beads had a main peak of the (101) crystal face and were highly crystallized with XRD diffraction peaks of anatase-type $TiO_2$ according to an XRD analysis. In addition, the $TiO_2$ thin films showed photocatalytic properties such that they could decompose a methyl orange solution under illumination with UV light. As the number of bilayers of the(PDDA/TALH) thin film increased, the photocatalytic property of the $TiO_2$-coated glass beads increased with the increase in the thin film thickness. The surface morphologies and optical properties of glass beads coated with $TiO_2$ thin films with different coating numbers were measured by field emission scanning electron microscopy(FE-SEM), X-ray diffraction(XRD) and by UV-Vis spectrophotometry(UV-vis).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.10
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• pp.826-832
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• 1998

In this study the thin films with the structure of Si+SiO$_2$+TiN are made by RF supttering method. TiN, which has small diffusion coefficient and low resistivity, is evaporated between SiO$_2$ and Al layers. It investigates the V-R characteristics depending on the thickness of SiO$_2$ which is used as insulation layer and researches its effects on voltage stability of thin film and varistor. These films show very small resistance valus in negative(-) voltage and large and large value in positive voltage band, and with the increase of voltage, resistance value is rapidly reduced and the satisfactory characteristic of varistor is shown at +1[V]. It is found that resistance value of TiN thin film is small and also TiN thin film has more current than the thin film which is not evaporated by TiN thin film. When Al electrode is evaporated of SiO$_2$ thin film, spiking occurs, but the spiking can be prevented with evaporation of TiN between SiO$_2$ and Al layers and this thin films in made easily because of its good attachment. With the increase of voltage, the resistance is changed into non-linear pattern and the bidirectional varistor characteristic is shown and then its theory can be verified by this experiment. Accordingly, when TiN is evaporated of Si Wafer(n-100), it obtains better voltage-resistance than thin film which is not evaporated and also when varistor character is used electrically to automatic control element such as elimination of flame, power distribution arrestor and constant voltage compensation, satisfactory reproducibilities are expected.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.9
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• pp.423-429
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• 2002

RuOx thin films were fabricated by the method of liquid delivery MOCVD using Ru(C$_{8}$ $H_{13}$ $O_2$)$_3$ as the precursor and their thermal effects and conductivity were investigated. Ru films deposited at 25$0^{\circ}C$ were annealed at $650^{\circ}C$ for 1min with Ar, $N_2$ or N $H_3$ ambient. The changes of the micro-structure, the surface morphology and the electrical resistivity of the Ru films after annealing were studied. Ar gas was more effective than $N_2$ and N $H_3$ gases as an ambient gas for the post annealing of the Ru films, because of smaller resistivity and denser grains. The X-ray diffraction and X-ray photoelectron spectroscopy results indicate that the Ru $O_2$ phase and the silicidation are not observed regardless of the ambient gases. The minimum resistivity of the Ru film is found to have the value of 26.35 $\mu$Ω-cm in Ar ambient. Voids were formed at Ru/TiN interface of the Ru layer after annea1ing in $N_2$ ambient. The $N_2$ gas generated due to the oxidation of the TiN layer accumulated at the Ru/TiN interface, forming bubbles; consequently, the stacked film may peel off the Ru/TiN interface.e.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1375-1381
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• 2018

In this paper, we studied coatings of the DLC thin film for improving loosening torque of dental implant screw. We used a filtered arc ion plating process which can realize the most dense DLC layer by coating the DLC thin film on the surface of the dental abutment screw. It showed both hardness comparable to diamond and low friction coefficient similar to graphite, and to improve the loosening phenomenon by increasing the screw tightening force Cr/CrN, Ti/TiN or Ti/TiN/Cr/CrN buffer layers were deposited for 5 to 10 minutes to improve the adhesion of the DLC thin film to the surface of the Ti (Gr.5), and then the DLC thin film was coated for about 15 minutes. As a result, the Cr/CrN buffer layer exhibited the highest hardness of 29.7 GPa, the adhesion of 18.62N on average, and a very low coefficient of friction of less than 0.2 as a whole. And we measured loosening torque after one million times with masticatory movement simulator. As a result, the values of the coated screw loosening torque were clearly higher than those of the uncoated screw. From this, it was found that the DLC coating was effective methods improving the loosening torque. In addition, it was confirmed that the cytotoxicity test and cell adhesion test showed high biocompatibility.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.244-245
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• 2015

PEALD TiN 금속 전극을 갖는 MOS device에서 SC1 ($NH_4/H_2O_2/H_2O=1:2:5$), SPM ($H_2SO_4/H_2O_2=10:1$), $H_2O_2$ etch chemical을 이용해 TiN 식각 후 oxide 표면 잔류 Ti에 의한 전기적 특성 분석을 진행 하였다. Etch chemical 중 SPM을 이용한 소자의 전기적 특성이 우수하였는데, 이는 잔류Ti atom의 양이 다른 etch chemical을 사용한 것 대비 낮았기 때문이다. 이로 인하여 낮은 leakage current, less frequency dependence의 특성이 관찰되었다. 또한, 후속 열처리를 통해 더욱 우수한 특성이 관찰 되었다. 이러한 공정기술은 single 전극을 갖는 CMOS 형성 시 사용 될 수 있을 것으로 기대된다.