• Korean Journal of Materials Research
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• v.24 no.11
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• pp.632-638
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• 2014

We investigated the effects of DMAB (Borane dimethylamine complex, C2H10BN) in electroless Ni-B film with addition of DMAB as reducing agent for electroless Ni plating. The electroless Ni-B films were formed by electroless plating of near neutral pH (pH 6.5 and pH 7) at $50^{\circ}C$. The electroless plated Ni-B films were coated on screen printed Ag pattern/PET (polyethylene terephthalate). According to the increase of DMAB (from 0 to 1 mole), the deposition rate and the grain size of electroless Ni-B film increased and the boron (B) content also increased. In crystallinity of electroless Ni-B films, an amorphization reaction was enhanced in the formation of Ni-B film with an increasing content of DMAB; the Ni-B film with < 1 B at.% had a weak fcc structure with a nano crystalline size, and the Ni-B films with > 5 B at.% had an amorphous structure. In addition, the Ni-B film was selectively grown on the printed Ag paste layer without damage to the PET surface. From this result, we concluded that formation of electroless Ni-B film is possible by a neutral process (~green process) at a low temperature of $50^{\circ}C$.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.104-111
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• 2001

B-doped hydrogenated amorphous silicon carbide (a-SiC:H) thin films were prepared by plasma-enhanced chemical-vapor deposition in a gas mixture of $SiH_4, CH_4,\;and\; B_2H_6$. Physical and chemical properties of a-SiC:H films grown with varing the ratio of $B_2H_6/(SiH_4+CH_4)$ were characterized with various analysis methods including scanning electron microscopy (SEM), X-ray diffractometry (XRD), Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, secondary ion mass spectroscopy (SIMS), UV absorption CH_4spectroscopy and electrical conductivity measurements. With the B-doping concentration, the doping efficiency and the micro-crystallinity were decreased and the film became amorphous when $B_2H_6/(SiH_4{plus}CH_4)$ was over $5{\times}10^{-3}$. The addition of $B_2H_6$ gas during deposition decreased the H content in the film by lowering the quantity of Si-C-H bonds. Consequently, the optical band gap and the activation energy of a-SiC:H films were decreased with increasing the B-doping level.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.1-5
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• 2022

We investigate the effect of surface disorder on the lower critical field (H_c1) of MgB₂ thin films with a thickness of 850 nm, where the disorder on the surface region is produced by the irradiation of 140 keV Co ions with the dose of 1 × 10¹⁴ ions/cm². The thickness of the damaged region by the irradiation is around 143 nm, corresponding to ~17% of the whole thickness of the film, thereby forming the disordered MgB₂ overlayer on the pure MgB₂ layer. The magnetic field dependence of magnetization, M(H), for the pristine MgB₂ thin film and the film with overlayer is measured at various temperatures, and H_c1 is determined from the difference (△M) between the Meissner line and magnetization signal with the criterion of △M = 10^-3 emu. Intriguingly, the film with the disordered overlayer shows a remarkably large H_c1(0) = 108 Oe compared to the H_c1(0) = 84 Oe of pristine film, indicating that the disordered MgB₂ overlayer on the pure MgB₂ layer serves to prevent the penetration of vortices into the sample. These results provide new ideas for improving the superheating field to design high-performance superconducting radio-frequency cavities.

• Journal of the Korean institute of surface engineering
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• v.41 no.2
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• pp.43-47
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• 2008

Cubic boron nitride(c-BN) films were deposited on tungsten carbide insert tool by microwave plasma enhanced chemical vapor deposition(MPECVD) from a gas mixture of triethyl borate$(B(C_2H_5O)_3)$, ammonia $(NH_3)$, hydrogen$(H_2)$ and argon(Ar). The qualities of deposited thin film were investigated by x-ray diffrac-tion(XRD), field emission scanning electron microscopy(FE-SEM) and micro Raman spectroscope. The surface morphologies of the synthesised BN as well as crystallinity appear to be highly dependent on the flow rate of $B(C_2H_5O)_3$ and $(NH_3)$ gases. The deposited film had more crystallized phases with 5 scem of $B(C_2H_5O)_3$ and $(NH_3)$ gases than with 2 sccm, and the phase was identified as c-BN by micro Raman spectroscope and XRD. The adhesion strength were also increased with increasing flow rates of $B(C_2H_5O)_3$ and $(NH_3)$ gases.

• Journal of the Korean Society of Food Culture
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• v.7 no.4
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• pp.297-301
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• 1992

To investigate effects of the surface finishing methods (A : conventional press stone, B : enclosing in polyethylene (PE) bag, C : press-tone wrapped with PE film and D : covered with Chinese cabbage leaves 4cm in thickness on Kimchi) on Kimchi quality, pH-values, redness, film forming yeast growth, hardness and sensory quality of Kimchi during storage (for 60 days, at $10{\pm}5^{\circ}C$) in glass vessel $(11{\times}30cm)$ were investigated. pH of the top layer of A, C and D sample were higher than the optimum pH (4.2) of Kimchi, film forming yeast occurred on the surface of Kimchi, color of top layer Kimchi juice was darkened, and panel score of freshness and firmness was significantly worse (p<0.01) than that of sample B. However, in the case of Kimchi stored in PE bag (B), film forming yeast were can't detected visually in the surface of Kimchi, pH values were low as good quality Kimchi, freshness and firmness panel scores and hardness were significantly better (p<0.01) than A, C and D, and redness of juice of top layer of B was also preserved clearly for 60 days. Accordingly among the four surface finishing methods, the B-method was most effective in preserving of y of Kimchi.

• Progress in Superconductivity and Cryogenics
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• v.16 no.3
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• pp.7-9
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• 2014

Single-crystal like $MgB_2$ thin film was grown on (000l) $Al_2O_3$ substrate by using hybrid physical-chemical vapor deposition (HPCVD) system. Single crystal properties were studied by X-ray diffraction (XRD) and the full width at half maximum (FWHM) of the (0001) $MgB_2$ peak is $15^{\circ}$, which is very close to that has been reported for $MgB_2$ single-crystal. It indicates that the crystalline quality of thin film is good. Temperature dependence on resistivity was investigated by physical property measurement system (PPMS) in various applied fields from 0 to 9 T. The upper critical field ($H_{c2}$) and irreversibility field ($H_{irr}$) were determined from PPMS data, and the estimated values are comparable with that of $MgB_2$ single-crystals. The thin film shows a high critical temperature ($T_c$) of 40.4 K with a sharp superconducting transition width of 0.2 K, and a high residual resistivity ratio (RRR=21), it reflects that $MgB_2$ thin film has a pure phase structure.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.193-200
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• 2023

Titanium alloy (grade-4) is commonly used in industrial and medical applications. To improve its corrosion resistance and biocompatibility for medical use, it is necessary to form a titanium oxide film. In this study, the morphology of the oxide film formed by anodizing Ti-grade 4 using different electrolytes was analyzed. Wetting properties before and after surface modification with SAM coating were also observed. Electrolytes used were categorized as A, B, and C. Electrolyte A consisted of 0.3 M oxalic acid and ethylene glycol. Electrolyte B consisted of 0.1 M NH₄F and 0.1 M H₂O in ethylene glycol. Electrolyte C consisted of 0.07 M NH₄F and 1 M H₂O in ethylene glycol. Samples B and C exhibited a porous structure, while sample A formed a thickest oxide film with a droplet-like structure. AFM analysis and contact angle measurements showed that sample A with the highest roughness exhibited the best hydrophilicity. After surface modification with SAM coating, it displayed superior hydrophobicity. Despite having the thickest oxide film, sample A showed the lowest insulation resistance due to its irregular structure. On the other hand, sample C with a thick and regular porous oxide film demonstrated the highest insulation resistance.

• Journal of the Korean institute of surface engineering
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• v.23 no.1
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• pp.34-43
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• 1990

Al-Si piston alloys such as AlS10CuMg have been anodized to examine apossibility of forming a hard film aat relatively higher temperatures compard with those in conventional sulfuric acid processes. Three types of electrolytes have been employed in this study ; electrolyte A(15% H2SO4, $0^{\circ}C$), electrolyte B(12% H2SO4, 1% oxalic, $10^{\circ}C$), electrolyte C(tartaric acid 125g/L+oxalic 75g/L+aluminum sulfate 225g/L, $25^{\circ}C$). Hard anodisine process in electrolyte B at a current density of 1.54A/dm2 produced a harder film of VHN 396 at a relatibely low film forming voltage compared with those obtained in other electrolyte at equivalent current density. A liner relationship between hardness and abrasion resistance exists for Al-Si piston alloys. The hardness of anodized film decreasees with increasing silicon content in Al-Si alloys and also with bath temperature. The film hardeness of Na-modified alloy os higher than that of P-modified alloy due to its finer microstructre. The film on the silicon phase in Al-Si alloys is observed to be formed by lateral growth of oxide film nucleated at surroundings.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.535-540
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• 1994

Thin film magnet was fabricated by radio frequency magnetron sputtering using $Nd_13/(Fe.Co)_{70}B_{17}$ alloy target and magnetic properties were investigated according to sputtering conditions from the metallurgical point of view. we could obtain the best preferred orientation of $Nd_2Fe_{14}B$ phase at substrate temperatures between $450^{\circ}C$ and $460^{\circ}C$ with the input power 150W, and thin films had the anisotropic magnetic properties. But, as the thickness of thin film increased, the c-axis orientation gradually tended to be disordered and magnetic properties also become isotropic. Just like Nd-Fe-B meltspun ribbon, the microstructure of thin film magnet was consisted of very find cell shaped $Nd_2Fe_{14}B$ phase and the second phase along grain boundary. While, domain structure showed maze patterns whose magnetic easy axis was was perpendicular to film plane of thin film. It was concluded from these results that the perpendicualr anisotropy in magnetization was attributed to the perpendicular alignment of very find $Nd_2Fe_{14}B$ grains in thin film.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1761-1763
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• 1998

ITO(Iridium-Tin Oxide) thin film, as discharge electrodes in AC PDP, should have low resistivity and high transparency. Regarded as a high deposition rate method, the ITO thin film fabricated by the facing target sputtering system has been studied in this paper. The electrical property of the ITO film deposited below $150^{\circ}C$ is not satisfied. The SEM pictures show that the ITO films deposited below $150^{\circ}C$ are amorphous. After being annealed the amorphous ITO films become crystalline, and for this reason, the electrical property of amorphous ITO films can be effectively improved by annealing process. An ITO film with the resistivity as low as $1.99{\times}10^{-4}$ and transparency above 85% has be gotten after vacuum annealing at $300^{\circ}C$ for 2 hours while deposited at $75^{\circ}C$. The corresponding deposition rate is $220{\AA}/min$.