• Journal of the Korean Magnetics Society
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• v.16 no.5
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• pp.240-244
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• 2006

In this paper, magnetic properties and annealing behavior of spin valve structures using Mo(MoN) layers as underlayers were studied varying the thickness of the underlayers. The spin valve structure was consisted of Si substrate/$SiO_2(2,000{\AA})/Mo(MoN)(t{\AA})/NiFe(21\;{\AA})/CoFe(28\;{\AA})/Cu(22\;{\AA})/CoFe(18\;{\AA})/IrMn(65\;{\AA})/Ta(25\;{\AA})$. Also, MoN films were deposited on Si substrates and their thermal annealing behavior was analyzed. The resistivity of the MoN film increased as the $N_2$ gas flow rate was increased. After annealing at $600^{\circ}C$, XRD results did not show peaks of silicides. XPS results indicated MoN film deposited with 5 sccm of $N_2$ gas flow rate was more stable than the film deposited with 1 sccm of $N_2$ gas flow rate. The variations of MR ratio and magnetic exchange coupling fold were small for the spin valve structures using Mo(MoN) underlayers up to thickness of45 ${\AA}$. MR ratio of spin valves using MoN underlayers deposited with various $N_2$ gas flow rate was about 7.0% at RT and increased to about 7.5% after annealing at $220^{\circ}C$. Upon annealing at $300^{\circ}C$, the MR ratio decreased to about 3.5%. Variation of $N_2$ gas flow rate up to 5 sccm did not change the MR ratio and $H_{ex}$ appreciably.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.308-317
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• 1993

The study is related to the synthesis of acrylic acid by selective oxidation of acrolein on Mo-V-W multicomponent mixed oxide catalysts. Mo-V-W-O(WVM), Mo-V-O/Mo-W-O(VM/WM), Mo-W-O/Mo-V-O(WM/VM) and mechanical mixtures of Mo-V-O and Mo-W-O(M-VM+WM) were prepared and characterized by BET, XRD, SEM and EPMA. Catalytic activity of these catalysts was tested in a continuous fixed bed reactor. In WVM catalysts small amount of tungsten added to VM increased surface area and selectivity of acrylic acid, but excess amount of tungsten decreased reaction rate of acrolein and selectivity. VM/WM catalysts, VM supported on WM, showed higher activity and selectivity than WM/VM catalysts where WM is supported on VM. Phase cooperation between WM and VM was observed in mechanical mixture of WM and VM and they showed higher yield than WM or VM.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1109-1113
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• 1999

sothemal reduction at $50^{\circ}C$ using $Pt/MoO_3$ or $Pt/MoO_3/SiO_2$ made by dry impregnation or physical mixture of $Pt^{\circ}$ and $MoO_3$ demonstrated that the $H_2$ uptake vis $H_2$ spillover from Pt into $MoO_3$ was enhanced as calcination temperature was increased. Surface area of exposed Pt crystallites measured by CO chemisorption was decreased with higher calcination temperature. In addition, TEM showed that $MoO_x$ overlayers were formed on Pt crystallites after calcination at $400^{\circ}C$. Consequentially, it was found that this increased active contact sites between Pt and $MoO_3$ due to surface morphological change was one of the dominant factors for this increased $H_2$uptake via $H_2$ spillover from Pt crystallites into $MoO_3$.

• Journal of the Korean Chemical Society
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• v.38 no.2
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• pp.160-168
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• 1994

Pentadentate Schiff base molybdenum(Ⅴ) complexes such as [Mo(Ⅴ)O(Sal-DET)(NCS)] and [Mo(Ⅴ)O(Sal-DPT)(NCS)] were synthesized by Sabat method. The structure of these complexes were identified by elemental analysis, spectroscopy, and thermogravimetric analysis(T.G.A.). It was found that the mole ratio of Schiff base ligand to the complexes was found to be 1 : 1. The redox processes of the complexes were investigated by cyclic voltammetric and differential pulse polarographic technique in nonaqueous solvent containing 0. 1 M tetraethyl ammonium perchlorate(TEAP) as supporting electrolyte at glassy carbon electrode. It was found that diffusion controlled reduction processes of four steps with one electron were 2Mo(Ⅴ)$\rightleftarrow^{e-}$ Mo(Ⅴ)Mo(Ⅳ) $\longrightarrow^{e-}$ 2Mo(Ⅳ), Mo(Ⅳ) $\longrightarrow^{e-}$ Mo(Ⅲ) $\longrightarrow^{e-}$ Mo(Ⅱ)

• Journal of the Korean Magnetics Society
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• v.3 no.3
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• pp.221-228
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• 1993

The general requirements of recording media include recording performance, environmental stability, runnability on the drive or deck, and manufacturability. CoCrMo thin films were prepared using RF sputtering system for a study on chemical stability. Surface degradation of the CoCrMo thin film was studied by SEM, XPS and AES. Surface degradation was found to be dependent of sputtering condition and Mo content. Addition of Mo to CoCr thin film improved dramatically its surface degradation resistance in dilute sulfuric acid, as indicated by active-passive transition appeared in electrochemical polarization curve. Futhermore, the passive current density was decreased with increasing Mo content. The reduction in a number density of corrosion sites by Mo addition vms observed, after accelerated corrosion test. AES survey indicated that corrosion occured on the site with Cr depletion and highly concentrated chloride ions.

• Journal of the Korean Ceramic Society
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• v.36 no.5
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• pp.471-477
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• 1999

Fe and Fe-Mo binder were used to produce TiB2 based cermet by a pressureless sintering. The densification behaviour of TiB2-Fe-Mo cermet during liquid-phase sintering in argon was studied in relation to binder phase charactertics. The effects of Mo addition and sintering condition on the sintering behaviour and mechanical properties were also investigated. TiB2-based cermets with Fe-Mo binder composition showed a better sinterability than the cermets with only Fe binder. In TiB2-Fe-Mo cermet higher densities in the wide temperature range were obtained and also fully densified sintered cermet were obtained at 1873K The enhancement in the densification phenomenon of TiB2-Fe-Mo system can be explained by improved liquid phase wettability associated with the roles of Mo components as solute atoms. When Fe-Mo binders were used cermets with a finer grain size and enhanced mechanical properties wereproduced and new phases such as Fe2B and Mo2FeB2 were observed in the sintered cermet. The highest bending strength was obtained from the 20vol% Fe-Mo cermet and these hardness-fracture toughness combination in the wide binder compositions is better than that of TiB2-Fe cermet. In order to improve mechanical properties microstructure control with high purity powders is desirable because high purity powders prevent the formation of Fe2B and Mo2FeB2 phase which comsume the ductile binder phase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.403-409
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• 2018

Inconel 713C which of a commercial Ni super alloy have the composition of 70 % Ni, 12 % Cr, 6 % Al and 4 % Mo. Mo is very expensive and have some economic value to recover in the alloy. In this study, liquid-liquid exraction(solvent extraction and stripping) has been performed to separate Mo from the synthetic leaching solution of spent Inconel 713C alloy and prepare to Mo powder by dying, evaporation and heat treatment. The experiments were conducted by using synthetic leaching solution which was prepared $NaMoO_4$ $2H_2O$ by dissolved in distilled water. Alamine336 and Cyanex272 dissolved in kerosene were used as extractants. The extraction percentage of Mo by Alamine336 is 99 % in the condition of the range of pH 1 to 4 and 1 % of concentration of Alamine336. The stripping solutions are used by HCl, $H_2SO_4$ and $HNO_3$ solutions and the concentrations were controlled by distilled water. The concentrations of HCl, $H_2SO_4$ and $HNO_3$ as stripping solutions are increased, the stripping percentages of Mo are increased and the stripping percentage of Mo by $HNO_3$ is higher than other stripping solutions. After liquid-liquid extraction and heat treatment, $MoO_3$ powder which of the purity of 97.5 % was prepared.

• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.95-98
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• 2007

In this paper, the magnetic properties and the annealing behavior of spin valve structures with Mo(MoN) underlayers were studied for various underlayer thickness. The spin valve structure was Si substrate/Mo(MoN)$(t{\AA})/NiFe(21{\AA})/CoFe(28{\AA})/Cu(22{\AA})/CoFe(18{\AA})/IrMn(65{\AA})/Ta(25 {\AA})$. Mo and MoN films were deposited on Si substrates and their thermal annealing behavior was analyzed. The deposition rate of the MoN thin film was decreased and tile resistivity of the MoN thin films were increased as the $N_2$ gas flow was increased. The variations of MR ratio and magnetic exchange coupling field of spin valve structure were smaller with MoN underlayers than that with Mo underlayers up to thickness of $51{\AA}$. MR ratio of spin valves with Mo underlayers was 2.86% at room temperature and increased up to 2.91 % after annealing at $200^{\circ}C$. Upon annealing at $300^{\circ}C$, the MR ratio decreased about 2.16%. The MR ratio of spin valves structure with MoN underlayers for $N_2$ gas flow 1 sccm was 5.27% at room temperature and increased up to 5.56% after annealing at $200^{\circ}C$. Upon annealing at $300^{\circ}C$, the MR ratio decreased about 4.9%.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.37-44
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• 1999

Hardness characteristics and microstructures of $Nb/MoSi_2$ laminate composites were evaluated from the variation of fabricating conditions such as preparation temperature, applied pressure and pressure holding time. $Nb/MoSi_2$ laminate composites composed of $MoSi_2$ powder and Nb sheets were fabricated by the hot press. From experimental results, it was found that the lamination from Nb sheet and $MoSi_2$ powder was an excellent strategy to improve hardness characteristics of monolithic $MoSi_2$. However, interfacial reaction products like(Nb, Mo)$SiO_2\;and\;Nb2Si_3$ formed at the interface of $Nb/MoSi_2$ and increased with fabricating temperature.

• International Journal of Ocean System Engineering
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• v.2 no.4
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• pp.244-249
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• 2012

In this study, a monolithic MoSi2 matrix reinforced with 20 vol% SiC particles, a SiC/MoSi2 composite matrix reinforced with 20 vol% ZrO2 particles, and a ZrO2/MoSi2 composite were fabricated using hot press sintering at $1350^{\circ}C$ for 1 h under a pressure of 30 MPa. The Vickers hardness and sliding wear resistance of the monolithic MoSi2, ZrO2/MoSi2, and SiC/MoSi2 composite were investigated at room temperature. A wear behavior test was carried out using a disk-type wear tester with a silicon nitride ball. The ZrO2/MoSi2 composite showed an average Vickers hardness value and excellent wear resistance compared with the monolithic MoSi2 and SiC/MoSi2 composite at room temperature.