• Title/Summary/Keyword: titanium (Ti)

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The Effect of Titanium Interlayer on the Adhesion Properties of TiN Coating (Titanium Interlayer가 TiN 박막의 밀착특성에 미치는 영향)

  • Kong, S.H.;Kim, H.W.;Shin, Y.S.;Kim, M.I.
    • Journal of the Korean Society for Heat Treatment
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    • v.5 no.1
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    • pp.1-12
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    • 1992
  • In order to improve adhesive force of TiN film, we sputtered titanium as interlayer before TiN deposition by Plasma Enhanced Chemical Vapour Deposition. We observed changes of hardness and adhesion at a various thickness of titanium interlayer and also examined analysis. At the critical thickness of the titanium interlayer(about $0.2{\mu}$), adhesive force of TiN films were promoted mostly. But over the critical thickness, a marked reduction of adhesive force was showed, because of the internal stress of titanium interlayer. From AES analysis, the adhesion improvement of TiN films was mainly caused by nitrogen diffusion into titanium interlayer during TiN deposition process which relieved stress concentration at TiN coating-substrate interface.

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Synthesis of Titanium Carbide Nano Particles by the Mechano Chemical Process

  • Ahn, In-Shup;Park, Dong-Kyu;Lee, Yong-Hee
    • Journal of Powder Materials
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    • v.16 no.1
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    • pp.43-49
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    • 2009
  • Titanium carbides are widely used for cutting tools and grinding wheels, because of their superior physical properties such as high melting temperature, high hardness, high wear resistance, good thermal conductivity and excellent thermal shock resistance. The common synthesizing method for the titanium carbide powders is carbo-thermal reduction from the mixtures of titanium oxide($TiO_2$) and carbon black. The purpose of the present research is to fabricate nano TiC powders using titanium salt and titanium hydride by the mechanochemical process(MCP). The initial elements used in this experiment are liquid $TiCl_4$(99.9%), $TiH_2$(99.9%) and active carbon(<$32{\mu}m$, 99.9%). Mg powders were added to the $TiCl_4$ solution in order to induce the reaction with Cl-. The weight ratios of the carbon and Mg powders were theoretically calculated. The TiC and $MgCl_2$ powders were milled in the planetary milling jar for 10 hours. The 40 nm TiC powders were fabricated by wet milling for 4 hours from the $TiCl_4$+C+Mg solution, and 300 nm TiC particles were obtained by using titanium hydride.

In-situ Synthesis and Investment Casting of Titanium Matrix (TiC+TiB) Hybrid Composites (Ti기 (TiC+TiB) 하이브리드 복합재료 반응생성합성 및 정밀주조)

  • Sung, Si-Young;Park, Keun-Chang;Lee, Sang-Hwa;Kim, Young-Jig
    • Journal of Korea Foundry Society
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    • v.24 no.3
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    • pp.159-164
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    • 2004
  • The aim of the present work is to investigate the possibility of in-situ synthesis and net-shape forming of the titanium matrix (TiC+TiB) hybrid composites using a casting route. From the scanning electron microscopy, electron probe micro-analyzer, X-ray diffraction and thermodynamic calculations, the spherical TiC and needle like TiB reinforced hybrid titanium matrix composites could be obtained in-situ by the conventional melting and casting route between titanium and $B_4C$. No melt-mold reaction occurred between the titanium matrix (TiC+TiB) hybrid composites and the SKK mold, since the mold is consisted with interstitial and substitutional metal-mold reaction products. Not only the sound in-situ synthesis but also the economic net-shape forming of the titanium matrix (TiC+TiB) hybrid composites could be possible by the conventional casting route.

A Study on the Synthesis of Titanium Nitride by SHS(Self-propagating High-temperature Synthesis) Method (자체반응열 고온합성법에 의한 질화티타늄 합성에 관한 연구)

  • Ha, Ho;Kim, Kwang-Rae;Lee, Hee-Cheol
    • Journal of the Korean Ceramic Society
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    • v.30 no.12
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    • pp.1096-1102
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    • 1993
  • Titanium nitride was synthesized by reacting Ti powder with nitrogen gas using SHS method. In this process, the effects of nitrogen pressure, dilution with TiN, or additiion of titanium hydride(TiH1.924) on the conversion of Ti to TiN were investigated. In particular, much effects were given to solve the problem of the conversion drop due to partial melting and subsequent sintering of Ti parciels, by controlling combustion temperature and combustion wave velocity via mixing Ti powder with TiN or/and TiH1.924. For the diluted titanium powders with TiN, the conversion close to 100% was resulted when the nitrogen pressure was over 8atm and with diluent content of 60wt%, and the self-propagating reaction was not sustained when the diluent content was higher than 60wt%. For samples mixed to be 55wt% in Ti component in the mixture of Ti, TiH1.924, and 45% TiN, the conversion was closed to 100% when the amount of titanium hydride added was over 7wt% and the nitrogen pressure was higher than 5atm. The combustion reaction, however, was not sustained when titanium hydride added was more than 10wt%.

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Carbothermal Reduction of Spray Dried Titanium-Cobalt-Oxygen Based Oxide Powder by Solid Carbon (분무건조법에 의해 제조된 Ti-Co-O계 산화물 분말의 고체 탄소에 의한 환원/침탄)

  • 이길근;문창민;김병기
    • Journal of Powder Materials
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    • v.11 no.1
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    • pp.28-33
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    • 2004
  • In the present study, the focus is on the analysis of carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fined TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under a flowing argon atmosphere. The changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. The synthesized titanium-cobalt-oxygen based oxide powder has a mixture of $TiO_2$ and $CoTiO_3$. This oxide powder was transformed to a mixed state of titanium car-bide and cobalt by solid carbon through four steps of carbothermal reduction steps with increasing temperature; reduction of $CoTiO_3$ to $TiO_2$ and Co, reduction of $TiO_2$, to the magneli phase($Ti_nO_{2n-1}$, n>3), reduction of the mag-neli phase($Ti_nO_{2n-1}$, n>3) to the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases, and reduction and carburization of the $Ti_nO_{2n-1}$(2$\leq$n$\leq$3) phases to titanium carbide.

Evaluation of Pess Formability for Ti-6Al-4V Sheet at Elevated Temperature (Ti-합금판재(Ti-6Al-4V)의 고온 성형성 평가)

  • Park, J.G.;Park, N.K.;Kim, Y.S.
    • Transactions of Materials Processing
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    • v.19 no.4
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    • pp.230-235
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    • 2010
  • Titanium alloy sheets have excellent specific strength and corrosion resistance as well as good performance at high temperature. Recently, titanium alloys are widely employed not only for aerospace parts but also for bio prothesis and motorcycle. However, the database is insufficient in the titanium alloy for press forming process. In this study, the effect of temperature on the forming limit diagram was investigated for Ti-6Al-4V titanium alloy sheet through the Hecker‘s punch stretching test at elevated temperature. Experimental results obtained in this study can provide a database for the development of press forming process at elevated temperature of Ti-6Al-4V titanium alloy sheet. From the experimental studies it can be concluded that the formability of Ti-6Al-4V titanium alloy sheet is governed by the ductile failure for the testing temperature. The formability of Ti-6Al-4V titanium alloy sheet at $700^{\circ}C$ increases about 7 times compared with that at room temperature.

Selective Carbonization and Nitridation of Titanium in (ZrTi)O2 Powders Synthesized by Copreciptation Method

  • Shin Soon-Gi
    • Korean Journal of Materials Research
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    • v.15 no.10
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    • pp.662-666
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    • 2005
  • Solid solutions of $(Zr/Ti)O_2$ were prepared in powder form by the coprecipitation technique. After mixing with carbon or exposing to nitrogen gas at elevated temperature, titanium cations selectively diffused out from the oxide compound to form titanium carbide (TiC) or titanium nitride (TiN), respectively. TiN formed strong interfacial contacts between the oxide grains. In contrast, TiC formed as small crystallites on oxide grains but did not bind the matrix grains together. TiN therefore played a role in strengthening the interparticle bonding, but TiC weakened the bonding between grains. Partial diffusion of titanium cations also led to nanolayered structure being formed between the oxide grains, which provided weak interfacial layers that fractured in a step-wise fashion.

Effect of Cobalt Oxide on Carbothermal Reduction of Spray Dried Titanium-Cobalt-Oxygen Based Oxide Powder (분무건조법에 의해 제조된 Ti-Co-O계 산화물 분말의 환원/침탄반응에 미치는 코발트 산화물의 영향)

  • Lee, Gil-Geun;Kim, Chan-Young
    • Journal of Powder Materials
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    • v.12 no.5 s.52
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    • pp.336-344
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    • 2005
  • In the present study, the focus is on the effect of cobalt oxide powder in the carbothermal reduction of the titanium-cobalt-oxygen based oxide powder by solid carbon for the optimizing synthesis process of ultra fine TiC/Co composite powder. The titanium-cobalt-oxygen based oxide powder was prepared by the combination of the spray drying and desalting processes using the titanium dioxide powder and cobalt nitrate as the raw materials. The titanium-cobalt-oxygen based oxide powder was mixed with carbon black, and then this mixture was carbothermally reduced under flowing argon atmosphere. Changes in the phase structure and thermal gravity of the mixture during carbothermal reduction were analysed using XRD and TGA. Titanium-cobalt-oxygen based oxide powder desalted at $600^{\circ}C$ had a mixture of $TiO_2\;and\;Co_{3}O_4$. And the one desalted at $800^{\circ}C$ had a mixture of $TiO_2\;and\;CoTiO_3$. In the case of the former powder, the reduction of cobalt oxide powder in the titanium-cobalt-oxygen based oxide powder occurred at lower temperature than the latter one. However, the carbothermal reduction of titanium dioxide powder in the titanium-cobalt-oxygen based oxide powder with a mixture of $TiO_2\;and\;Co_{3}O_4$ occurred at higher temperature than the one with a mixture of $TiO_2\;and\;CoTiO_3$. And also, the former powder showed a lower TiC formation ability than the latter one.

Acidic Properties and Catalytic Activity of Titanium Sulfate Supported on TiO2

  • Sohn, Jong-Rack;Lee, Si-Hoon;Cheon, Park-Won;Kim, Hea-Won
    • Bulletin of the Korean Chemical Society
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    • v.25 no.5
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    • pp.657-664
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    • 2004
  • Titanium sulfate supported on $TiO_2$was prepared by impregnation of powdered $TiO_2$with an aqueous solution of titanium sulfate followed by calcining in air at high temperature. For Ti$(SO_4)_2/TiO_2$ samples calcined at 300 $^{\circ}C$, no diffraction lines of titanium sulfate are observed at $Ti(SO_4)_2$loading up to 30 wt%, indicating good dispersion of $Ti(SO_4)_2$ on the surface of $TiO_2$. The acidity of the catalysts increased in proportion to the titanium sulfate content up to 20 wt% of $Ti(SO_4)_2$. 20 wt% $Ti(SO_4)_2/TiO_2$ calcined at 300 $^{\circ}C$ exhibited maximum catalytic activities for 2-propanol dehydration and cumene dealkylation. The catalytic activities for these reactions, were correlated with the acidity of catalysts measured by ammonia chemisorption method.

Microstructure and Tensile Property of In-Situ (TiB+TiC) Particulate Reinforced Titanium Matrix Composites (반응생성 합성에 의한 (TiB+TiC) 입자강화 Ti기 복합재료의 미세조직 및 인장특성 평가)

  • Choi, Bong-Jae;Kim, Young-Jig
    • Korean Journal of Metals and Materials
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    • v.48 no.8
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    • pp.780-789
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    • 2010
  • The aim of this study is to evaluate the microstructure and tensile property of in-situ (TiB+TiC) particulate reinforced titanium matrix composites (TMCs) synthesized by the investment casting process. Boron carbide ($1,500{\mu}m$ and $150{\mu}m$) was added to the titanium matrix during vacuum induction melting, which can provide the in-situ reaction of $5Ti+B_4C{\rightarrow}4TiB+TiC$. 0.94, 1.88 and 3.76 wt% of $B_4C$ were added to the melt. The phases identification of the in-situ synthesized TMCs was examined using scanning electron microscopy, an X-ray diffractometer, an electron probe micro-analyzer and transmission electron microscopy. Tensile properties of TMCs were investigated in accordance with the reinforcement size and volume fraction. The improvement of tensile property of titanium matrix composites was caused by load transfer from the titanium matrix to the reinforcement and by grain refinement of titanium matrix and reinforcements.