• Particle and aerosol research
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• v.11 no.1
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• pp.9-19
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• 2015

This study investigated the effects of ball mill operation condition on the morphology of raw powders in the dry-type milling process using three types of ball mills traditional ball mill, stirred ball mill and planetary ball mill. Furthermore, since spherical powders offer the best combination of high hardness and high density, the optimum milling condition to produce sphere-shaped powders was studied. The applied rotation speed ranged from 200rpm (low rotation speed) to 700rpm (high rotation speed). The used ball size ranged from 1mm to 5mm. The metal powder morphology was studied using SEM, XRD and PSA. The aimed spherical powders could be obtained under the optimum experimental conditions: traditional ball mill(200rpm, 1mm ball), planetary ball mill (500rpm, 1mm ball) and also planetary ball mill (700rpm, 1 and 3 mm ball). The results show to the development of new material using spherical type copper powder/CNT composites for air-craft and automotive applications.

• Journal of Powder Materials
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• v.15 no.2
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• pp.125-135
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• 2008

[ $TiO_2$ ] nanotubes for photocatalytic application have been synthesized by hydrothermal method. $TiO_2$ nanotubes are formed by washing process after reaction in alkalic solution. Nanotubes with different morphology have been fabricated by changing NaOH concentration, temperature and time. $TiO_2$ nanoparticles were treated inside NaOH aqueous solution in a Teflon vessel at $110^{\circ}C$ for 20 h, after which they were washed with HCl aqueous solution and deionized water. Nanotube with the most perfect morphology was formed from 0.1 N HCl washing treatment. $TiO_2$ nanotube was also obtained when the precursor was washed with other washing solutions such as $NH_4OH$, NaCl, $K_2SO_4$, and $Na_2SO_3$. Therefore, it was suggested that $Na^+$ ion combined inside the precursor compound slowly comes out from the structure, leaving nanosheet morphology of $TiO_2$ compounds, which in turn become the nanotube in the presence of hydroxyl ion. To stabilize the sheet morphology, the different type of washing treatment solution might be considered such as amine class compounds.

• Journal of Sericultural and Entomological Science
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• v.41 no.1
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• pp.54-60
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• 1999

Antheraea pernyi silk powder was prepared by treatment with HCl and NaOH. The degree of hydrolysis of Antheraea pernyi silk fiber was examined. The morphology and structural characteristics of Antheraea pernyi silk powder were investigated by using SEM, FTIR and X-ray diffractometer. As the concentration of HCl and NaOH and tratment temperature increased, in general, the degree of hydrolysis of Antheraea pernyi silk fiber increased. On the other hand, the degree of hydrolysis of Antheraea pernyi treated with 3 N NaOH at 120$^{\circ}C$ for 24 hr was 70 wt%, which was lower than that of 90$^{\circ}C$(83 wt%). The morphology of acid/alkali resistance fraction of Antheraea pernyi silk fibroin was transformed from fiber form to powered one with an increase of hydrolysis. The conformation of Antheraea pernyi silk powder characterized by FT-IR spectrometer and X-ray diffractometer ${\beta}$-sheet and ${\alpha}$-helix structure.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.533-542
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• 1995

The present study investigated the effectiveness of pretreatment on dentin bonding. The adhesive resin was 5% 4-methacryloyloxyethyl trimellitate anhydride (4-META) in methyl methacrylate (MMA) combined with poly-MMA powder. Polymerization of this resin was initiated by tri-n-butyl borage (TBB). Ground bovine dentin samples were etched with either an aqueous solution of 10% citric (10-0 solution) (Group I) or aqueous solution of 10% citric acid and 3% ferric chloride(10-3 solution) (Group ll ). After etching, the primer (an aqueous solution of 35% hydroxyethyl methacrylate (HEM- A) and 5% glutaraldehyde was applied on the differently etched surfaces (Group III , Group IV). The 10-0 treatment showed the lowest tensile bond strength, followed by the 10-3 treatment, primer application after the 10-0 treatment and primer application after the 10-3 treatment. The relationship among the surface morphology after pretreatment, fractured surface morphology and tensile bond strength was examined. It revealed that the surface morphology change by different pretreatment influenced the bond strength and the resulting fractured surface morphology. The correlation of tensile bond strength with the fracture morphology was explained.

• Archives of Metallurgy and Materials
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• v.65 no.3
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• pp.993-996
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• 2020

In this study, we demonstrate a facile and cost-effective way to synthesize Nd-Fe-B of various shapes such as powders, rods and fibers using electrospinning, heat-treatment and washing procedures. Initially Nd-Fe-B fibers were fabricated using electrospinning. The as-spun Nd-Fe-B fibers had diameters ranging 489 to 630 nm depending on the PVP concentration in reaction solutions. The different morphologies of the Nd₂Fe₁₄B magnetic materials were related to the difference in thickness of the as-spun fibers. The relationships between the as-spun fiber thickness, the final morphology, and magnetic properties were briefly elucidated. The intrinsic coercivity of Nd₂Fe₁₄B changed with the change in morphology from powder (3908 Oe) to fiber (4622 Oe). This work demonstrates the effect of the Nd-Fe-B magnetic properties with morphology and can be extended to the experimental design of other magnetic materials.

• Korean Journal of Materials Research
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• v.27 no.9
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• pp.489-494
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• 2017

ZnS powder was synthesized using a relatively facile and convenient glycothermal method at various reaction temperatures. ZnS was successfully synthesized at temperatures as low as $125^{\circ}C$ using zinc acetate and thiourea as raw materials, and diethylene glycol as the solvent. No mineralizers or precipitation processes were used in the fabrication, which suggests that the spherical ZnS powders were directly prepared in the glycothermal method. The phase composition, morphology, and optical properties of the prepared ZnS powders were characterized using XRD, FE-SEM, and UV-vis measurements. The prepared ZnS powders had a zinc blende structure and showed average primary particles with diameters of approximately 20~30 nm, calculated from the XRD peak width. All of the powders consisted of aggregated secondary powders with spherical morphology and a size of approximately $0.1{\sim}0.5{\mu}m$; these powders contained many small primary nanopowders. The as-prepared ZnS exhibited strong photo absorption in the UV region, and a red-shift in the optical absorption spectra due to the improvement in powder size and crystallinity with increasing reaction temperature. The effects of the reaction temperature on the photocatalytic properties of the ZnS powders were investigated. The photocatalytic properties of the as-synthesized ZnS powders were evaluated according to the removal degree of methyl orange (MO) under UV irradiation (${\lambda}=365nm$). It was found that the ZnS powder prepared at above $175^{\circ}C$ exhibited the highest photocatalytic degradation, with nearly 95 % of MO decomposed through the mediation of photo-generated hydroxyl radicals after irradiation for 60 min. These results suggest that the ZnS powders could potentially be applicable as photocatalysts for the efficient degradation of organic pollutants.

• Journal of the Korean Ceramic Society
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• v.53 no.5
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• pp.529-534
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• 2016

Nanocrystalline powder of zirconia stabilized with 8 mol% yttria (YSZ) has been synthesized through oxalate process using $ZrOCl_2{\cdot}8H_2O$ and $Y(NO_3)_3{\cdot}6H_2O$ as starting materials. Understanding of the characteristic changes of YSZ powder as a function of processing conditions is crucial in developing dense and porous microstructures required for fuel cell applications. In this research, microstructure change, surface area, particle shape and particle size were measured as a function of different processing conditions such as calcination temperature, stirring speed and concentration of starting materials. The resultant crystallite sizes were calculated by XRD-LB (X-Ray Diffraction Line-Broadening) method, BET method, and morphology of the crystal was observed in TEM and FE-SEM. The TEM examination showed that the powder synthesized with 0.7 M of YSZ concentration had a spherical morphology with sizes ranging from 20 to 40 nm. However, the powder was gradually aggregated above 1.0 M of YSZ concentration with the aggregation being intensified as the YSZ concentration was increased.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1328_1329
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• 2009

Nano porous indium tin oxide (ITO) powder was synthesized employing a new route sol-gel combustion hybrid method using Ketjen Black as a fuel. The nano porous ITO powder was composed of $SnCl_4$-98.0% and $In(NO_3)_3{\cdot}XH_2O$-99.999%, produce with a $NH_4OH$ with sol-gel method as a catalyst [1,2]. Crystal structures were examined by powder X-ray diffraction (XRD), and those results show shaper intensity peak at $25.6^{\circ}(2{\Theta})$ of $SnO_2$ by increased sintering temperature. A particle morphology as well as crystal size was investigated by scanning electron microscopy(FE-SEM), and the size of the nano porous powder was found to be in the range of 20~30nm. ITO films could controlled by nano porous powder at various sintering temperature in this paper[3,4]. The sol-gel combustion method was offered simple and effective route for the synthesis of nano porous ITO powder[5].

• Journal of the Korean Ceramic Society
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• v.47 no.2
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• pp.127-131
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• 2010

Biomimetic whisker-like apatite was formed on thermally and NaOH-treated titanium powder in a simulated body fluid (SBF). In the early process of the SBF immersion, the surface structure of the titanium powder was loosened, possibly due to the dissolution of $Na^+$ ions on the surface of the titanium powder into SBF. When immersed for 7 days in SBF, fine precipitates appeared on the titanium surfaces; the coating layer (<200 nm in thickness) consisted of nanostructured, amorphous whisker-like and particulate phase, observed by TEM. With the extension of the immersion time to 16 days, the chrysanthemum flower type morphology of carbonated hydroxyapatite with a nanocrystallinity was developed on the surface of the titanium powder.

• Journal of the Korean Ceramic Society
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• v.14 no.3
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• pp.163-168
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• 1977

As a wet chemical drying process "hot petroleum drying method" was applied and developed for preparing uniformly fine oxide powder with high purity and sinterreactivity. Using this method solution of sulfates was dried in hot petroleum bath (~17$0^{\circ}C$) to sulfate powder from which corresponding mullite doped by Fe3+ ion was formed. Particle size, shape, decomposition by heat, and phase identification of sulfate andoxide powders determined by DTA, TGA, X-ray diffraction, analysis and electron microscopy: sulfate powder prepared by this drying method is an intimate mixture of the amorphous form of uniformly and finely distributed spherical particles (0.05-0.1$\mu$). Mullitization with the sulfate powder occurs at 110$0^{\circ}C$ in air. The morphology of mullite particle made by firing the sulfate powder at 135$0^{\circ}C$ in oxygen atmosphere is granular of 0.1-0.3$\mu$ in size. This drying process proved to be a very effective method for preparing fine, homogeneous, and highly sinterreactive multicomponent oxide powder without conventional ceramic process of mixing, milling, and granulating. This process can be also applied for preparing electronic ceramic materials which are requisite for high purity and homogeneity.mogeneity.