• 자원리싸이클링
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• 제32권2호
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• pp.19-32
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• 2023

본 연구에서는 수소분위기 내 사염화타이타늄의 마그네슘 열환원을 이용한 수소화타이타늄 분말 합성 과정 중 온도 및 소결 조건에 따른 분말 특성 변화를 조사하였다. 수소화타이타늄 생성에 미치는 온도의 영향을 검토하기 위해 1023~1123 K의 1 atm 수소분위기에서 약 30 분간 사염화타이타늄과 마그네슘을 반응시켰다. 환원반응 후 생성된 수소화타이타늄 분말의 소결이 진행되도록 0~120 분간 환원반응 온도를 유지시켰으며, 반응 종료 후 회수된 생성물의 산소농도를 분석하였다. 실험결과, 1023 K에서는 TiH_1.924 이 생성되었으나, 1073K 및 1123 K에서는 TiH_1.924와 TiH_1.5의 혼합물이 생성되었다. 또한, 반응온도가 높을수록 생성된 수소화타이타늄 분말의 수소농도는 감소하였다. 반응온도 및 소결시간이 증가할수록 분말의 산소농도는 감소하였으며, 이는 분말의 비표면적 감소에 기인하였다. 반응온도 1073 K 및 소결시간 120 분 실험조건에서 최저 산소농도 0.246 mass%인 TiH_1.924와 TiH_1.5의 혼합물이 제조되었다.

• 한국지반환경공학회 논문집
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• 제11권1호
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• pp.5-11
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• 2010

본 연구에서는 에어로졸 증착법을 사용하여 광촉매 $TiO_2$ 박막을 제조하기 위하여 원심분리기의 회전속도, vibration milling 시간에 의한 입경 변화 등과 같은 운전인자의 영향을 검토하였고, 제조된 고정화 $TiO_2$ 광촉매 박막의 경우와 $TiO_2$ 광촉매 분말을 부유 상태로 존재시킨 경우와의 막투과 특성의 변화를 실험적으로 비교검토 하였다. 원심분리기의 회전속도 1000-3000rpm 에서 얻어진 $TiO_2$ 분말은 저온 분사 성형법(aerosol deposition, AD)으로 $TiO_2$ 박막을 제조하는데 있어서 nozzle powder 막힘 현상과 같은 문제점을 나타내었다. 한편, vibrating milling에 의해 제어된 $TiO_2$ 분말의 평균입경 크기는 vibrating milling 2시간 후 약 420nm로 AD법을 이용한 입자의 증착에 효과적인 것으로 나타났다. XRD 분석 결과, 광촉매에 효과적인 아나타제 상을 잘 유지하고 있는 것으로 나타났으며, 이러한 결과로부터 vibrating milling은 $TiO_2$ 분말을 제어하는데 있어 적절한 전처리 공정임을 확인할 수 있었다. 제조된 $TiO_2$ 박막의 여과 특성으로 $TiO_2$ 분말을 분리막의 표면에 고정화 한 경우가 부유 상태일 경우보다 더 높은 막투과 유속을 나타내었다.

• 한국재료학회지
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• 제33권6호
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• pp.242-250
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• 2023

Titanium, which has excellent strength and toughness characteristics, is increasingly used in the aerospace field. Among the titanium alloys used for body parts, more than 80 % are Ti-6Al-4V alloys with a tensile strength of 931 MPa. The spark plasma sintering (SPS) method is used for solidification molding of powder manufactured by the mechanical milling (MM) method, by sintering at low temperature for a short time. This sintering method avoids coarsening of the fine crystal grains or dispersed particles of the MM powder. To improve the mechanical properties of pure titanium without adding alloying elements, stearic acid was added to pure titanium powder as a process control agent (PCA), and MM treatment was performed. The properties of the MM powder and SPS material produced by solidifying the powder were investigated by hardness measurement, X-ray diffraction, density measurement and structure observation. The processing deformation of the pure titanium powder depends on the amount of stearic acid added and the MM treatment time. TiN was also generated in powder treated by MM 8 h with 0.50 g of added stearic acid, and the hardness of the powder was higher than that of Ti-6Al-4V alloy when treated with MM for 8 h. When the MM-treated powder was solidified in the SPS equipment, TiC was formed by the solid phase reaction. The SPS material prepared as a powder treated with MM 8 h by adding 0.50 g of stearic acid also formed TiN and exhibited the highest hardness of Hv1253.

• 한국분말재료학회지
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• 제20권5호
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• pp.338-344
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• 2013

Fe-TiC composite was fabricated from Fe and TiC powders by high-energy milling and subsequent spark-plasma sintering. The microstructure, particle size and phase of Fe-TiC composite powders were investigated by field emission scanning electron microscopy and X-ray diffraction to evaluate the effect of milling conditions on the size and distribution of TiC particles in Fe matrix. TiC particle size decreased with milling time. The average TiC particle size of 38 nm was obtained after 60 minutes of milling at 1000 rpm. Prepared Fe-TiC powder mixture was densified by spark-plasma sintering. Sintered Fe-TiC compacts showed a relative density of 91.7~96.2%. The average TiC particle size of 150 nm was observed from the FE-SEM image. The microstructure, densification behavior, Vickers hardness, and fracture toughness of Fe-TiC sintered compact were investigated.

• 한국분말재료학회지
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• 제12권4호
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• pp.249-254
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• 2005

Titanium dioxide was prepared by Polymer Complex Solution Method(PCSM) according to the mole ratio of Titanium (IV) isopropoxide(TTIP)/solvent and polymer(Poly Ethylene Glycol). Polymer electrolytes were usually made by dispersing preproduced ceramic nanoparticles in a polymer matrix. Using this method, pure and nano-sized $TiO_2$ powder was synthesized through a simple procedure and polymer entrapment route. At the optimum amount of the polymer, the titanium ions are dispersed in solution and a homogeneous polymeric network is formed. The maximum intensity of anatase phase of $TiO_2$ was achieved by calcining at $500^{\circ}C$ for 2h. The synthesized $TiO_2$ powders were nano-sized and the average size was about 50nm. Anatase/Rutile ratio of the synthesized $TiO_2$ was 70%/30%.

• 한국재료학회지
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• 제18권8호
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• pp.411-416
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• 2008

In this research, fine-structure TiO2 bulks were fabricated in a combined application of magnetic pulsed compaction (MPC) and subsequent sintering and their densification behavior was investigated. The obtained density of $TiO_2$ bulk prepared via the combined processes increased as the MPC pressure increased from 0.3 to 0.7 GPa. Relatively higher density (88%) in the MPCed specimen at 0.7 GPa was attributed to the decrease of the inter-particle distance of the pre-compacted component. High pressure and rapid compaction using magnetic pulsed compaction reduced the shrinkage rate (about 10% in this case) of the sintered bulks compared to general processing (about 20%). The mixing conditions of PVA, water, and $TiO_2$ nano powder for the compaction of $TiO_2$ nano powder did not affect the density and shrinkage of the sintered bulks due to the high pressure of the MPC.

• 청정기술
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• 제24권4호
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• pp.280-286
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• 2018

본 연구에서는 금속산화물 2종, $TiO_2$ 분말과 $Al_2O_3$ 분말을 이용하여 건식 조건에서의 기상 VOCs 흡착 성능을 평가하였으며, BET분석과 암모니아 in-situ FT-IR 분석을 통해 비표면적, 표면 산점을 분석하고 성능과의 상관성을 평가하였다. 그 결과 $TiO_2$ 분말, $Al_2O_3$ 분말은 각각 $317.6m^2\;g^{-1}$, $64m^2\;g^{-1}$의 비표면적을 갖으며, $TiO_2$ 분말의 경우 표면에 다수의 산점이 관찰되었다. 두 금속 산화물 분말을 이용하여 기상 VOCs 흡착 성능을 평가한 결과, 비표면적이 크고 다수의 산점을 보유한 $TiO_2$ 분말이 비교적 우수한 흡착 성능을 나타내었다. 특히 비표면적이 흡착성능에 직접적인 영향을 미치는 것으로 판단되며, 산점에 의한 영향에 대해서는 추가적인 연구가 요구된다. 우수한 흡착 성능을 나타낸 $TiO_2$를 기반으로 honeycomb, hollow fiber, disc의 성형체로 제조 한 결과, 분말보다 흡착 성능은 낮았으나 적용성 측면에서 유리하며 제조공정의 특성상 우수한 열적 내구성을 갖는 polymeric disc 흡착제의 경우, 수회의 고온 탈착공정 후에도 흡착 성능을 안정적으로 유지함을 확인하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.394-397
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• 2008

In this research, the fine-structure TiO2+Ti bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their densification behavior was investigated. The obtained density of $TiO_2$+Ti bulk prepared by the combined processes was increased with increasing MPC pressure from 0.7 to 1.7 GPa. Relatively higher density (88%) in the MPCed specimen at 0.7Gpa was attributed to the decreasing of the inter-particle distance of pre-compacted component. High pressure and rapid compaction by Magnetic Pulsed Compaction could reduce shrinkage rate (about 10%) of the sintered bulks compared to that of general processing (about 20%). Mixing conditions of PVA, water, Ti and $TiO_2$ nano powder for compaction of $TiO_2$ nano powder did not affect on density and shrinkage of the sintered bulks due to high pressure of MPC.

• 한국분말재료학회지
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• 제20권4호
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• pp.285-290
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• 2013

$Ti_2AlN$ composites are a laminated compounds that posses unique combination of typical ceramic properties and typical metallic(Ti alloy) properties. In this paper, the powder synthesis, SPS sintering, composite characteristics and machinability evaluation were systematically conducted. The random orientation characteristics and good crystallization of the $Ti_2AlN$ phase are observed. The electrical and thermal conductivity of $Ti_2AlN$ is higher than that of Ti6242 alloy. A machining test was carried out to compare the effect of material properties on micro electrical discharge drilling for $Ti_2AlN$ composite and Ti6242 alloy. Also, mixture table as a kind of tables of orthogonal arrays was used to know how parameter is main effective at experimental design. Consequently, hybrid $Ti_2AlN$ ceramic composites showed good machining time and electrode wear shape under micro ED-drilling process. This conclusion proves the feasibility in the industrial applications.

• 한국전기전자재료학회논문지
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• 제28권9호
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• pp.561-564
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• 2015

Nano-size $BaTiO_3$ powder was synthesized by relatively simple hydrothermal reaction method. Finely dispersed Ti hydroxide precursor was first precipitated using $Ti(SO_4)_2$ and NaOH solution by applying ultrasonic power and washed thoroughly to remove $SO_4{^{2-}}$ and $Na^+$ ion. Then hydrothermal reaction was done at $160^{\circ}C$ for 6 hrs using solution prepared by washed Ti hydroxide precursor slurry and $Ba(OH)_2{\cdot}8H_2O$ with Ti:Ba mole ratio of 1:1. 200 ~ 500 nm size and uniform size distributed $BaTiO_3$ powder was synthesized by relatively low temperature and simple process.