• 대한기계학회논문집A
• /
• 제21권10호
• /
• pp.1674-1682
• /
• 1997

Fatigue tests were performed to investigate the effect of ceramic coatings as in TiN and TiCN on fatigue crack growth properties of ceramic coated 1Cr-1Mo-0.25V steel with different coating thickness in laboratory air conditions. The experimental results are described with respect to a Paris equation, da/dN=C(.DELTA.K)$^{m}$ , where the crack growth rate of coated specimens provided as similar growth rate as that of the uncoated specimen regardless of coating thickness. Furthermore, it was observed that the type of coating layer had virtually no effect on crack growth rate in the full region of stress intensity factor range. And it was also appeared that the final crack length of TiCN coated specimens was short compared to that of TiN coated, and the substrate specimens, in which it was inferred due to lowering the toughness of coated material from high hardness of TiCN coating layer itself.

• 한국수소및신에너지학회논문집
• /
• 제16권2호
• /
• pp.122-129
• /
• 2005

The characteristics of hydrogen storage have been investigated in the Ti-Cr-Mo and Ti-Cr-V ternary alloys with bcc structure. The alloys were melted by arc furnace and remelted 4-5 times for homogeneity. The lattice parameters, microstructures and phases of the alloys were examined by SEM, EDX and XRD, and the Pressure-Composition isotherms of the alloys were measured. From these data the relationship of the maximum and effective hydrogen storage capacities vs. chemical composition, lattice parameter and the radius of tetrahedral site were analyzed and discussed. The results showed that all of these alloy, in the range of the this study, had mainly bcc solid solutions with small amount of Ti segregation due to a lower melting point of Ti compared with other elements. Lattice parameters of the alloys were very near to the atomic average values of lattice parameters of the constituent elements. It was also found that maximum hydrogen storage capacities of the Ti-Cr-Mo alloys increased with increasing Ti content and the radius of tetrahedral site but the effective hydrogen storage capacities decreased after showing the maximum. The hydrogen storage capacities of the Ti-Cr-V alloys were almost same even though the V contens were quite different from alloy to alloy and this could be attributed to the almost same Ti/Cr ratio of the alloys. The maximum effective hydrogen storage capacity of the Ti-Cr-Mo alloys was revealed at Ti content of about 40${\sim}$50 at% and radius of tetrahedral site of 0.43${\sim}$0.45 nm. The Ti-Cr-V alloys showed the hydrogen storage capacities of 3.0 wt% and effective hydrogen storage capacities of 1.5 wt%.

• 한국산학기술학회논문지
• /
• 제8권3호
• /
• pp.432-436
• /
• 2007

자동차 구조용 재료에 대하여 물리적 증착 코팅방법에 의한 트라이볼로지 특성을 연구 하였다. 코팅 재료는 탄화티탄(TiC)과 질화티탄(TiN)이다. 실험은 펠렉스 마찰 마모시험기를 이용하여 하중과 온도에 다양한 조건을 적용하여 마찰과 마모 거동에 대하여 트라이볼로지 특성을 결정하고 평가하였다. 연구결과 코팅하지 않았을 때보다 코팅하였을 때가 윤활 특성이 향상 되었고, 특히 내마모성 및 극압성 그리고 열 안정성이 훌륭하였다.

• 대한전자공학회논문지
• /
• 제27권11호
• /
• pp.55-61
• /
• 1990

비로소 높게 이온주입된 다결정 실리콘에 대한 C54 구조를 갖는 $TiSi_{2}$의 열적 안정성과 $TiSi_{2}{\times}As{\longrightarrow}TiAs{\times}2Si$의 TiAs 석출물 형성반응이 다결정 실리콘 박막의 표면 상태 거칠어짐에 미치는 영향을 살펴보았다.

• 한국재료학회지
• /
• 제24권11호
• /
• pp.625-631
• /
• 2014

To investigate the deformation properties of TiC-(5-20) mol% Mo solid solution single crystals at high temperature by compression testing, single crystals of various compositions were grown by the radio frequency floating zone technique and were deformed by compression at temperature from 1250K to 2270K at strain rates from $5.1{\times}10^{-5}$ to $5.9{\times}10^{-3}/s$. The plastic flow property of solid solution single crystals was found to be clearly different among a three-temperature range (low, intermediate and high temperature ranges) whose boundaries were dependent on the strain rate. From the observed property, we conclude that the deformation in the low temperature range is controlled by the Peierls mechanism, in the intermediate temperature range by the dynamic strain aging and in the high temperature range by the solute atmosphere dragging mechanism. The work softening tends to become less evident with an increasing experimental temperature and with a decreasing strain rate. The temperature and strain rate dependence of the critical resolved shear stress is the strongest in the high temperature range. The curves are divided into three parts with different slopes by a transition temperature. The critical resolved shear stress (${\tau}_{0.2}$) at the high temperature range showed that Mo content dependence of ${\tau}_{0.2}$ with temperature and the dependence is very marked at lower temperature. In the higher temperature range, ${\tau}_{0.2}$ increases monotonously with an increasing Mo content.

• 공업화학
• /
• 제5권3호
• /
• pp.478-500
• /
• 1994

융제법을 이용하여 육티탄산칼륨 wisker를 합성하였다. 바람직한 융제를 설정하기 위해 $V_2O_5$, $Bi_2O_3$, $B_2O_3$, $Pb_3O_4$, KCl, $K_4P_2O_7$, $K_2WO_4$ 그리고 $K_2MoO_4$의 8가지 형태의 융제가 조사되었으며 반응온도와 반응시간, $K_2CO_3$에 대한 $TiO_2$의 몰비, $K_2CO_3$와 $TiO_2$의 혼합물에 대한 flux의 몰비, 티탄산칼륨 섬유의 합성을 위한 서냉효과 등의 변수들이 결정화에 미치는 바를 조사하였다. 적절한 융제는 $K_2MoO_4$ 및 $K_2WO_4$였으며 이 두 flux를 사용한 적절한 섬유상 결정화 조건은 반응온도 $1000{\sim}1100^{\circ}C$, 반응시간 5hr, 시료 $K_2CO_3$에 대한 $TiO_2$의 혼합물에 대한 융제의 몰비는 4.0 그리고 $K_2CO_3$에 대한 $TiO_2$의 몰비는 6.0이 가장 바람직하였으며 아울러 서냉조작은 장섬유의 성장에 효과적이었다.

• 한국재료학회지
• /
• 제31권7호
• /
• pp.392-396
• /
• 2021

Expensive PCBN or ceramic cutting tools are used for processing of difficult-to-cut materials such as Ti and Ni alloy materials. These tools have the problem of breaking easily due to their high hardness but low fracture toughness. To solve these problems, cutting tools that form various coating layers are used in low-cost WC-Co hard material tools, and research on various tool materials is being conducted. In this study, binderless-WC, WC-6 wt%Co, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are densified using horizontal ball milled WC-Co, WC-Co-Mo₂C powders, and spark plasma sintering process (SPS process). Each SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are almost completely dense, with relative density of up to 99.5 % after the simultaneous application of pressure of 60 MPa and almost no significant change in grain size. The average grain sizes of WC for Binderless-WC, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are about 0.37, 0.6, 0.54, and 0.43 ㎛, respectively. Mechanical properties, microstructure, and phase analysis of SPSed Binderless-WC, WC-6 wt%Co-1 wt% Mo₂C, and WC-6 wt%Co-2.5 wt% Mo₂C hard materials are investigated.

• 공업화학
• /
• 제7권4호
• /
• pp.670-678
• /
• 1996

방사성 폐기물 소각로의 배기가스 중에 포함되어 있는 NOx를 제거하기 위하여 선택적 촉매 환원법에 활용되는 촉매들의 특성을 조사하였다. 촉매는 $V_2O_5$, $MoO_3$, 그리고 $SnO_2$를 하니컴 형태의 $TiO_2$ 담체에 담지시켜 제조하였으며 촉매의 종류, 반응온도, feed의 조성, $NH_3$/NO 몰비의 영향 등이 반응특성에 미치는 영향을 실험실 규모의 반응기에서 조사하였다. 10% $V_2O_5/TiO_2$ 촉매가 $350^{\circ}C$에서 94.4%의 높은 $NO{\rightarrow}N_2$ 전환율을 보였으며 열적 안정성이 좋은 $MoO_3$의 첨가는 높은 전환율을 보이는 온도범위를 확장시켜 주었다.

• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2004년도 춘계학술강연 및 발표대회 강연 및 발표논문 초록집
• /
• pp.12-12
• /
• 2004

• Journal of Welding and Joining
• /
• 제14권6호
• /
• pp.93-100
• /
• 1996

Effect of a flux composition on weld metal toughness in submerged arc welding with 60kgf/$\textrm{mm}^2$ grade C-Mo type wires was investigated and interpreted in terms of weld metal microstructure and hardenability. Flux workability was also studied by characterizing a weld bead profile. Compared to other weld metals, .weld metal used alumina basic flux with nickel showed lowest oxygen content, highest hardenability and the most acicular ferrite. The highest impact toughness of that weld metal, however, was attributed to the tough matrix due to the nickel rather than to the larger amount of acicular ferrite. Manganese silicate flux had better workability than alumina basic flux, showing broader welding conditions resulting in a depth-to-width ratio of 0.5. The composition of oxides in the weld metal was dependent on the flux composition, showing MnO-SiO$_2$-TiO in manganese silicate flux and MnO-SiO$_2$-Al$_2$O$_3$-TiO in alumina basic flux. MnO-SiO$_2$composition in both oxides was similar to a tephroite.