• Advances in nano research
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• v.1 no.4
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• pp.211-218
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• 2013

A low-cost, green and reproducible citric acid assisted synthesis of nanocrystalline $Al_{0.5}Ag_{0.5}TiO_3$ (n-AAT) powder is reported. X-ray, FTIR, energy dispersive X-ray, transmission electron microscopy and scanning electron microscopy analyses are performed to ascertain the formation of n-AAT. X-ray diffraction data analysis indicated the formation of monoclinic structure. Spherical shaped particles having the sizes of 3-15 nm are found. The mechanism of nano-transformation for the soft-chemical synthesis of n-AAT has been explained using simple organic chemistry rules and nucleation and growth theory. Dielectric study revealed that AAT ceramic might be a suitable candidate for capacitor applications.

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.298-302
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• 2018

Photocatalytic properties of nitrogen doped titanium dioxide were investigated. Photocatalytic degradation of methylene blue under UV and visible light was carried out to characterize N-doped $TiO_2$. The result of XPS indicated that nitrogen atoms substitute for oxygen sites within the crystal structure of $TiO_2$. In the UV-Vis DRS spectra, N-doped amorphous $TiO_2$ absorbed UV light with little absorption of visible light, while the absorption of visible light of amorphous/anatase $TiO_2$ remarkably increased. Methylene blue photocatalytic degradation appeared by the irradiation of UV or visible light onto the N-doped anatase phase of $TiO_2$. However, the degradation rate of visible light was lower than that of UV light. The photocatalytic degradation rate of the amorphous/anatase $TiO_2$ sample was higher than that of the anatase $TiO_2$. These results indicate that the high surface area of amorphous/anatase $TiO_2$ sample, which was about three times larger than those of the anatase $TiO_2$ sample, may be related to small particles of N-doped anatase $TiO_2$.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.634-638
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• 1998

Monodisperse, spherical $PMSQ/TiO_2$ composite fine powders were prepared by modified sol-gel process where 300 nm $TiO_2$ fine powders were used as seed particles for hetero-condensation with hydrolyzed MTMS (Methyltrimethoxysilane). The reaction was carried out under $N_2$ atmosphere at ambient temperature using $NH_3$ as a catalyst. Methanol was used as a solvent. Powder was obtained by the filtration of the solution with a glass filter and washing with acetone. The stirring rate, reaction temperature, $[H_2O]/[MTMS]$ and $[MTMS]/[TiO_2]$ ratio were varied to investigate shapes and sizes of particles. Monodisperse particles of $1-2{\mu}m$ diameter were obtained with [MTMS]=0.2 M, $[NH_3]=0.6M$, $[H_2O]/[MTMS]=100$, $[MTMS]/[TiO_2]=10-50$ at ambient temperature with mild stirring condition. These composite particles had a contact angle of almost 180 degree contact angle with water, which proves their excellent hydrophobicity. The study of UV absorption spectra showed that they have UV protecting effect.

• Korean Journal of Materials Research
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• v.20 no.8
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• pp.429-433
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• 2010

In this study, activated carbon (AC) as a carbon source was modified with different concentrations of cobalt chloride ($CoCl_2$) to prepare a Co-AC composite, and it was used for the preparation of Co-AC/$TiO_2$ composites with titanium oxysulfate (TOS) as the titanium precursor. The physicochemical properties of the prepared Co-AC/$TiO_2$ composites were characterized by $N_2$ adsorption at 77 K, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The photocatalytic treatments of organic dyes were examined under an irradiation of visible light with different irradiation times. $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine AC, which was $389\;m^2/g$. From the XRD results, the Co-AC/$TiO_2$ composites contained a mixturephase structuresof anatase and rutile, but a cobalt oxide phase was not detected in the XRD pattern. The EDX results of the Co-AC/$TiO_2$ composites confirmed the presence of various elements, namely, C, O, Ti, and Co. Subsequently, the decomposition of methylene orange (MO, $C_{14}H_{14}N_3NaO_3S$) and rhodamine B (Rh.B, $C_{28}H_{31}ClN_2O_3$) in an aqueous solution, respectively, showed the combined effects of an adsorption effect by AC and the photo degradation effect by $TiO_2$. Especially, the Co particles in the Co-AC/$TiO_2$ composites could enhance the photo degradation behaviors of $TiO_2$ under visible light.

• Journal of Powder Materials
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• v.20 no.3
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• pp.221-227
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• 2013

$TiB_2$-reinforced iron matrix composite (Fe-$TiB_2$) powder was in-situ fabricated from titanium hydride ($TiH_2$) and iron boride (FeB) powders by the mechanical activation and a subsequent reaction. Phase formation of the composite powder was identified by X-ray diffraction (XRD). The morphology and phase composition were observed and measured by field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The results showed that $TiB_2$ particles formed in nanoscale were uniformly distributed in Fe matrix. $Fe_2B$ phase existed due to an incomplete reaction of Ti and FeB. Effect of milling process and synthesis temperature on the formation of composite were discussed.

• Journal of Welding and Joining
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• v.14 no.2
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• pp.46-56
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• 1996

HAZ impact toughness of Ti-oxide steel was investigated and compared to that of a conventional Ti-nitride steel. Toughness variations of each steel with weld peak temperatures and cooling rates were interpreted with microstructural transformation characteristics. In contrast to Ti-nitride steel showing continuous decrease in HAZ toughness with peak temperature, Ti-oxide steel showed increase in HAZ toughness above $1400^{\circ}C$ peak temperature. The HAZ microstructure of the Ti-oxide steel is characterized by the formation of intragranular ferrite plate, which was found to start from Ti-oxide particles dispersed in the matrix of the steel. Large austenite grain size above $1400^{\circ}C$ promoted intragranular ferrite plate formation in Ti-oxide steel while little intragranular ferrite plate was formed in Ti-nitride steel because of dissolution of Ti-nitrides. Ti-oxides in the Ti-oxide steel usually contain MnS and have crystal structures of TiO and/or $Ti_2O_3$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1026-1029
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• 2006

Particulate reinforced titanium composites were produced by PM rout. Differents volumetric percentages of TiN reinforcements were used, 5,10,15 vol%. Samples were uniaxial pressed and vacuum sintered at differents temperatures between $1200-1300^{\circ}C$. Density, porosity, shrinkage, mechanical properties and microstructure were studied. Elastic properties and strength resistance were analysed by flexural strength and tension tests, and after the test, fractured samples were analysed too, obtaining a correlation between the fracture, interparticulated or intraparticulated, and the reinforcement addition.. Hardness and microhardness test were applied too, in order to complete the study about mechanical properties. In order to study wear resistance pin-on-disc test were used. In addition, the temperature influence, the reactivity between matrix and reinforcement, and the microstructures developed were observed by optical and electron microscopy.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2480-2486
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• 2018

Mesoporous $TiO_2$ microspheres were prepared by spray pyrolysis for photocatalysis. Post modification of $TiO_2$ by heat treatment was performed to optimize its photocatalytic performance. First, spherical $TiO_2$ particles with mesoporous structure were synthesized at pyrolysis temperatures of 500, 600, and $700^{\circ}C$. After characterization by XRD, SEM, and $N_2$ adsorption, a sample prepared at $500^{\circ}C$ was found to possess desirable properties for photocatalytic performance through post-modification. In methylene blue degradation, mesoporous $TiO_2$ microspheres synthesized at $500^{\circ}C$ outperformed other microspheres. Furthermore, samples obtained by spray pyrolysis at $500^{\circ}C$ were calcined at various temperatures as a post-modification process. The sample calcined at $350^{\circ}C$ showed improved photocatalytic activity due to optimal anatase crystallinity and surface area.

• International Journal of Precision Engineering and Manufacturing
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• v.5 no.1
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• pp.19-26
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• 2004

The growth of solid particles in TiC-XC-2vo1.% and TiC-XC-30vo1.% Ni alloys, (where X=Zr, W or Mo) was fitted to the equation of the form $d^3$-${do}^3$=Kt during the liquid phase sintering at 1,673K. Also, the grain growth behavior decreased markedly with the addition of ${MO}_2$C or WC and increased with the addition of zrC. The contiguity was greater in the alloys with a smaller growth rate constant and especially, decreased by increasing the Ni content in the TiC-${MO}_2$C-Ni alloy. In addition, the effect of the addition of carbide on the grain growth of 2 vo1.% Ni alloys was found to be similar to that of 30vo1.% Ni alloys. Consequently, the grain growth mechanism cannot be explained by the usual solution / reprecipitation process, but can be explained in terms of a new growth velocity equation, which includes the effects of contiguous carbide grain boundaries in restricting the overall grain growth, as well as the area of the solid / liquid interface in the alloy.

• Analytical Science and Technology
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• v.21 no.3
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• pp.229-236
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• 2008

$C/TiO_2$ composites were prepared with surface modified MWCNT sequentially after HCl treatment and TNB as titanium source. There is a single crystal structure which is anatase in all of the samples from the data of XRD. The SEM microphotographs of $C/TiO_2$ composites show that the $TiO_2$ particles were well mixed with the CNT. There are C, O and Al with strong Ti peaks in all samples from EDX results, and it also shows that the sample CT has much more amount of C and Ti content than that of sample HCT. Finally, the photocatalytic activities for the $C/TiO_2$ composites have more effective than that of pristine $TiO_2$.