• Journal of the Korean institute of surface engineering
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• v.24 no.1
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• pp.34-34
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• 1991

Corrosion behavior of TiN coated steel was studied in terms of thickness of interlayer Ti and TiN coating TiN was are ion plated to a thickness of 1$\mu\textrm{m}$ and 2$\mu\textrm{m}$ respectively with interlayer coating of Ti of 1$\mu\textrm{m}$, 2$\mu\textrm{m}$ and 3$\mu\textrm{m}$. Corrosion resistance of TiN coated steel was evaluated by anodic palarization test in 1N H2SO4 as well as salt spray test. Porosity of each coating was also tested by using SO2 test method. Corrosion current density decreased with increasing TiN coating thickness and Ti interlayer coating markedly enhanced the corrosion resistance. Ti interlayer coating of 2$\mu\textrm{m}$ and 3$\mu\textrm{m}$ prior to 2$\mu\textrm{m}$ TiN coating decreased the corrosion current density of active range by an order of 4 and that of passive range by an order of 2. This improvement was associated with the retardation of corrosive agent penetration with increasing coating thickness and inherent corrosion resistance of Ti interlayer. Ti interlayer coating was also very effective in improvement of corrosion resistance under salt atmosphere.

• Journal of the Korean institute of surface engineering
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• v.25 no.1
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• pp.34-39
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• 1992

Corrosion behavior of TiN coated steel was studied in terms of thickness of interlayer Ti and TiN coating. TiN was arc ion plated to a thickness of 1$\mu\textrm{m}$ and 2$\mu\textrm{m}$ respectively with interlayer coating of Ti of 1$\mu\textrm{m}$, $2\mu\textrm{m}$ and $3\mu\textrm{m}$. Corrosion resistance of TiN coated steel was evaluated by anodic palarization test in 1N $H_2$SO$_4$ as well as salt spray test. Porosity of each coating was also tested by using $SO_2$ test method. Corrosion current density decreased with increasing TiN coating thickness and Ti interlayer coating markedly enhanced the corrosion resistance. Ti interlayer coating of $2\mu\textrm{m}$ and $3\mu\textrm{m}$ prior to $2\mu\textrm{m}$ TiN coating decreased the corrosion current density of active range by an order of 4 and that of passive range by an order of 2. This improvement was associated with the retardation of corrosive agent penetration with increasing coating thickness and inherent corrosion resistance of Ti interlayer. Ti interlayer coating was also very effective in improvement of corrosion resistance under salt atmosphere.

• Tribology and Lubricants
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• v.4 no.2
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• pp.36-43
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• 1988

Titanium carbide(TiC) and titanium nitride(TiN) flims were deposited on $Si_3N_4$-TiC composite cutting tools by chemical vapor deposition(CVD) using $TiCl_4-CH_4-H_2$ and $TiCl_4-H_2-N_2$ gas mixtures, respectively. The nonmetal to metal ratio of deposit increases with increasing $m_{C/Ti}$(mole ratio of CH$_4$ to TiCl$_4$ in the input) for TiC coatings and $m_{N/Ti}$(mole ratio of N$_2$ to TiCl$_4$ in the input) for TiN coatings. The nearly stoiahiometric films could be obtained under the deposition condition of $m_{C/Ti}$ between 1.15 and 1.61 for TiC, and that of $m_{N/Ti}$ between 25 and 28 for TiN. Also maximum microhardness of the coatings can be obtained in these ranges. The interfacial region of TiC coatings on $Si_3N_4$-TiC ceramics is wider than that of TiN coatings according to Auger depth profile analysis, which indicates good interfacial bonding for TiC. Experimental results show that TiC coatings have an randomly equiaxed structure and Columnar structure with(220) preferred orientation can be obtained for TiN coatings. And, multilayer coatings have a dense and equiaxed structure.

• 전자공학회논문지 IE
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• v.48 no.2
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• pp.1-5
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• 2011

The epitaxial GaN layer of $120{\mu}m$ ~ $300{\mu}m$ thickness with a stripe Ti mask pattern is performed by hydride vapor phase epitaxy(HVPE). Ti strpie mask pattern is deposited by DC magnetron sputter on GaN epitaxial layer of $3{\mu}m$ thickness is grown by hydride vapor phase epitaxy(HVPE). Void are observed at point of Ti mask pattern when GaN layer is investigated by scanning electron microscope. The Crack of GaN layer is observed according to void when it is grown more thick GaN layer. The full width at half maximum of peak which is measured by X-ray diffraction is about 188 arcsec. It is not affected its crystallization by Ti meterial when GaN layer is overgrown on Ti stripe mask pattern according as it is measure FWHM of overgrowth GaN using Ti material against FWHM of first growth GaN epitaxial layer.

• Korean Journal of Materials Research
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• v.9 no.6
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• pp.577-582
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• 1999

In order to make the electroconductive $Si_3N_4$-TiN composities, the Si-Ti(N) compacts were nitrided at $1450^{\circ}C$ for 20hours, and then they were post-sintered by a gas-pressure-sintering technique at 1TEX>$1950^{\circ}C$ for 3.5 hours. As starting powders, commercial si powder of about $10\mu\textrm{m}$, two types of Ti powders of 100 and 325 mesh, and fine-sized TiN of $2.5\mu\textrm{m}$ powders were used. In the $Si_3N_4$-TiN sintered bodies used Ti powders, the relative density and fracture strength and electrical conductivity are low due to the existence of large amounts of coarse pores. However, in the $Si_3N_4$-TiN composite used TiN powder, the fracture toughness, fracture strength and electrical resistivity were $5.0MPa{\cdot}m^{1/2}$, 624MPa and $1400{\omega}cm$, respectively. The dispersion of TiN particles in the composite inhibited the growth of $Si_3N_4$ in the shape of rod and made strong strain field contrasts at the $Si_3N_4$-TiNinterfaces. It was recognized that microstructural control is required to improve the electrical conductivity and mechanical properties of $Si_3N_4$-TiN composites by dispersing TiN particles homogeneously.

• Korean Journal of Materials Research
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• v.27 no.11
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• pp.603-608
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• 2017

$Si_3N_4$ is a ceramic material attracting attention in many fields because of its excellent abrasion resistance. In addition, Ti and TiAl alloys are metals used in a variety of high temperature environments, and have attracted much attention because of their high strength and high melting points. Therefore, study of the interface reaction between $Si_3N_4/Ti$ and $Si_3N_4/TiAl$ can be a useful practice to identify phase selection and diffusion control. In this study, $Si_3N_4/Ti_5Si_3+TiN/TiN/Ti$ diffusing pairs were formed in the $Si_3N_4/Ti$ interfacial reaction and $Si_3N_4/TiN(Al)/Ti_3Al/TiAl$ diffusion pathway was identified in the $Si_3N_4/TiAl$ interfacial reaction. The diffusion layers of the interface reactions were identified and, to investigate the kinetics of the diffusion layer, the integrated diffusion coefficients were estimated.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.585-590
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• 1998

Fibrous $Na_xTi_nO_{2n+1}$ whisker was prepared by $H^+/Na^+$ ion-exchange on layered hydrous titanium dioxide ($H_2Ti_4O_9{\cdot}nH_2O$). The ion-exchange reaction was proceeded at 0.5~2.0 M NaOH solution. In the ion-exchange at 2.0 M NaOH solution, 73% of sodium was exchanged and the prepared $Na_xTi_nO_{2n+1}$ whisker was a fibrous crystal of about $10{\sim}20{\mu}m$ of length and about $0.7{\mu}m$ of diameter. The phase transition of the ion-exchange phases identified by the thermal analysis. The result showed that the $Na_xTi_nO_{2n+1}$ whisker was decomposed into $Na_2Ti_6O_{13}$ and $TiO_2$ in the temperature of $200{\sim}600^{\circ}C$.

• Journal of the Korean institute of surface engineering
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• v.34 no.3
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• pp.195-205
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• 2001

The surface characteristics of Ti/TiN films coated on sintered stainless steels (SSS) by electron beam physical vapour deposition (EB-PVD) were investigated. Stainless steel compacts containing 2, 4, and 10wt%Cu were prepared by the electroless Cu-plating method, which results in increased homogenization in the alloying powder. The specimens were coated with Ti and TiN with a 1.0$\mu\textrm{m}$ thickness respectively by EB-PVD. The microstructures were investigated using scanning electron microscopy (SEM). The corrosion behaviors were investigated using a potentiosat in 0.1 M $H_2$$SO_4$, and 0.1M HCl solutions and the corrosion surface was observed using SEM and XPS. The Ti coated specimens showed rough surface compared to Ti/TiN coated specimens. Ti and Ti/TiN coated SSS revealed a higher corrosion and pitting potential from anodic polarization curves than that of Ti and Ti/TiN uncoated SSS. In addition, Ti/TiN coated SSS containing 10wt% Cu exhibited good resistance to pitting corrosion due to the formation of a dense film on the surface and the decrease in interconnected porosity by electroless coated Cu.

• Journal of the Korean institute of surface engineering
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• v.33 no.2
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• pp.93-100
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• 2000

Effects of Ti content and Ti underlayer on the pitting behavior of TiN coated AISI 304 stainless steel have been studied. The stainless steel containing 0.1~1.0wt% Ti were melted with a vacuum melting furnace and heat treated at $1050^{\circ}C$ for 1hr for solutionization. The specimen were coated with l$\mu\textrm{m}$ and 2$\mu\textrm{m}$ thickness of Ti and TiN by E-beam PVD method. The microstructure and phase analysis were conducted by using XRD, XPS and SEM with these specimen. XRD patterns shows that in TiN single-layer only the TiN (111) Peak is major and the other peaks are very weak, but in Ti/TiN double-layer TiN (220) and TiN (200) peaks are developed. It is observed that the surface of coating is covered with titanium oxide (TiO$_2$) and titanium oxynitride ($TiO_2$N) as well as TiN. Corrosion potential on the anodic polarization curve measured in HCl solution increase in proportion to the Ti content of substrate and by a presence of the Ti underlayer, whereas corrosion and passivation current densities are not affected by either of them. The number and size of pits decrease with increasing Ti content and a presence of the coated Ti film as underlayer in the TiN coated stainless steel.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.266-267
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• 2011

질화갈륨(GaN)은 높은 전자이동도 및 높은 항복전계를 가지며 낮은 온저항으로 인하여 에너지효율이 우수하기 때문에 고출력 전력소자 분야에서 많은 관심을 받고 있다. GaN을 이용한 고출력 전력소자의 경우 상용화 수준에 근접할 만한 기술적 진보가 있었으나, 페르미 레벨 고정(Fermi-level pinning) 현상, 소자의 누설전류 등 아직 해결되어야 할 문제를 갖고 있다. 본 연구에서는 실리콘 기판 위에 성장된 GaN 에피탁시를 활용한 고출력 전력소자의 누설전류를 억제시키기 위해 오믹 접합 중 Au의 상호확산을 억제하는 중간층 금속(Mo or Ni)을 변화시켰으며 오믹 열처리 온도에 따른 특성을 비교 연구하였다. $Cl_2$와 $BCl_3$를 이용하여 0.6 ${\mu}m$ 깊이의 메사 구조가 활성영역을 형성하였고, Si 도핑된 n-GaN 위에 Ti/Al/Mo/Au (20/100/25/200 nm) 와 Ti/Al/Ni/Au (20/100/25/200 nm) 오믹 접합을 각각 설계, 제작하였다. 오믹 열처리시의 GaN 표면오염을 방지하기 위해 $SiO_2$ 희생층을 증착하였다. 오믹 접합 형성을 위해 각 750$^{\circ}C$, 800$^{\circ}C$, 850$^{\circ}C$에서 30초간 열처리를 진행 하였으며, 이후 6 : 1 BOE 용액으로 $SiO_2$ 희생층을 제거하였다. 750, 800, 850$^{\circ}C$에서 Ti/Al/Mo/Au 구조의 오믹 접합 저항은 각 2.56, 2.34, 2.22 ${\Omega}$-mm 이었으며, Ti/Al/Ni/Au 구조의 오믹 접합 저항은 각 43.72, 2.64, 1.86 ${\Omega}$-mm이었다. Isolation 누설전류를 측정하기 위해서 두 개의 오믹 접합 사이에 메사 구조가 있는 테스트 구조를 제안하였다. Isolation 누설전류는 Ti/Al/Mo/Au 구조에서 두 오믹 접합 사이의 거리가 25 ${\mu}m$이고 100 V일 때 750, 800, 850 $^{\circ}C$의 열처리 온도에서 각 1.25 nA/${\mu}m$, 2.48 nA/${\mu}m$, 8.76 nA/${\mu}m$이었으며, Ti/Al/Ni/Au 구조에서는 각 1.58 nA/${\mu}m$, 2.13 nA/${\mu}m$, 96.36 nA/${\mu}m$이었다. 열처리 온도가 증가하며 오믹 접합 저항은 감소하였으나 isolation 누설전류는 증가하였다. 750$^{\circ}C$ 열처리에서 오믹 접합 저항은Ti/Al/Mo/Au 구조가 Ti/Al/Ni/Au 구조보다 약 17배 우수하였고, 850$^{\circ}C$ 고온의 열처리 경우 Ti/Al/Mo/Au 구조의 isolation 누설전류는 8.76 nA/${\mu}m$로 Ti/Al/Ni/Au의 누설전류 96.36 nA/${\mu}m$보다 약 11배 우수하였다. Ti/Al/Mo/Au가 Ti/Al/Ni/Au 보다 오믹 접합 저항과 isolation 누설전류 측면에서 전력용 GaN 소자에 적합함을 확인하였다.