• Journal of Powder Materials
• /
• v.19 no.6
• /
• pp.416-423
• /
• 2012

This paper introduces an effect of a preparing $ZrO_2$-Ag composite on its mechanical properties and microstructure. In present study, $ZrO_2$-Ag was prepared by reduction-deposition route and wetting dispersive milling method, respectively. Two type of Ag powders (nano Ag and micron Ag size, respectively) were dispersed into $ZrO_2$ powder during wetting dispersive milling in D.I. water. Each sample was sintered at $1450^{\circ}C$ for 2hr in atmosphere, and then several mechanical tests and analysis of microstructure were carried out by bending test, hardness, fracture toughness and fracture surface microstructure. As for microstructure, the Ag coated $ZrO_2$ showed homogeneously dispersed Ag in $ZrO_2$ in where pore defect did not appear. However, $ZrO_2$-nano Ag and $ZrO_2$-micro Ag composite appeared Ag aggregation and its pore defect, which carried out low mechanical property and wide error function value.

• Journal of Powder Materials
• /
• v.17 no.4
• /
• pp.281-288
• /
• 2010

A carbon doped $TiO_2$ (C-$TiO_2$) photocatalyst, which shows good photocatalytic activity to Ultraviolet irradiation and visible irradiation, was successfully prepared by co-grinding of $TiO_2$ with ethanol or Activated Carbon(C), followed by heat treatment at $200^{\circ}C$ in air for 60 min. Ethanol and C were used as a representative agent of liquid and solid for carbon doping. Their influence on improving photocatalytic ability and carbon doping degree was studied with degradation of methyl orange and XPS analysis. The product prepared by co-grinding of $TiO_2$ with Ethanol had Ti-C and C-O chemical bonds and showed higher photocatalytic activity than the product prepared by co-grinding of $TiO_2$ with C, where just C-O chemical bond existed. As a result, mechanochemical route is useful to prepare a carbon doped $TiO_2$ photocatalyst activating to visible irradiation, where the solid-liquid operation is more effective than solid-solid operation to obtain a carbon doped $TiO_2$.

• Journal of Wetlands Research
• /
• v.14 no.4
• /
• pp.629-635
• /
• 2012

This study was conducted to evaluate the removal behaviors of DOM(dissolved organic matter) and phosphorus in eutrophic lake water by coagulation process with PAC(powdered activated carbon). It was observed that the removal characteristic of soluble matter was different from that of dissolved one, and the removal of DOM was effected by both pH and coagulant dosage. It was founded that PAC could increase the removal efficiency by an adsorption of DOM in coagulation process. A formation of soluble and colloidal matters resulted in the degradation of phosphorus removal efficiency in a chemical precipitation process. The phosphorus removal efficiency could be enhanced by an absorption of colloidal matter and dissolved complex with PAC addition. In addition, the PAC addition caused the increase of floc density in coagulation process, that led to the rise of sedimentation rate, and resulted in a significant improvement of solid-liquid separation efficiency.

• Resources Recycling
• /
• v.9 no.3
• /
• pp.3-12
• /
• 2000

A Study on the cementation for the recovery of Cu, Ni and Co with Mn metallic powders in leaching solution from the manganese nodule that have removed Fe ions was studied. The results showed that the recovery efficiencies of metal ions with Mn powders increased when the temperature, pH and the concentration of chloride ions were increased in mixed solution. And the recovery efficiencies of Cu was 98% and not changed with the addition amounts of Mn powders but, in case of Co and Ni, the recovery efficiencies were increased with the addition amounts. The particle size of precipitate was about $5\mu\textrm{m}$. From the results of experiment we proposed the two-step cementation process for the recovery of Cu, Ni and Co with Mn powders.

• Food Engineering Progress
• /
• v.13 no.2
• /
• pp.79-84
• /
• 2009

Effect of baking on the physicochemical properties including pH, moisture content, hardness, color, and spread factor was investigated using a model system of cookies incorporated with strawberry powder as a value-added food ingredient. Strawberry powder was incorporated into cookie dough at 4 levels (0, 2, 4, and 6% w/w) by replacing equivalent amount of wheat flour of the cookie dough. After aging and sheeting, cookies were baked at 170$^{\circ}C$ for 15 min in an oven. The baked cookies were cooled to room temperature for 1 hr and packed in airtight bags prior to all measurements. The pH of dough and hardness of cookies decreased significantly with increase in strawberry powder content (p<0.05). Moisture content of the dough was not significantly affected by strawberry powder but mean values tended to increase as the strawberry powder content increased. Lightness (L$^{*}$-value) and yellowness (b$^{*}$-value) significantly decreased as the strawberry powder content increased; on the other hand, redness (a$^{*}$-value) increased significantly (p<0.05). Spread factor also increased significantly as the strawberry content increased in the formulation (p<0.05). Finally, correlation analysis indicated that level of strawberry powder incorporation was well-correlated with all the physicochemical properties studied. It is also noted that there was a significant positive correlation between the moisture content of dough and spread factor (p<0.05).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.37 no.10
• /
• pp.1323-1329
• /
• 2008

For the development of new products using salmon, development of seasoned salmon powder was attempted and its characteristics were also examined. In the seasoned salmon powder prepared in this experiment (product P), the proximate composition was 42.1% moisture, 30.3% protein, 18.9% lipid, and 6.2% ash, and the Hunter color value showed 68.14 for the lightness, 7.86 for the redness, 19.13 for the yellowness and 35.12 for the color difference. TCA soluble-N content of product P was 360 mg/100 g, which is higher than that of commercial product (234 mg/100 g). In taste values, total value was 2.2 times higher in product P than in commercial product, and their major free amino acid was only glutamic acid. In both product P and commercial product, the major fatty acids were 16:0, 18:1n-9, 18:2n-6, and 22:6n-3. Total content of amino acid was higher in the product P (29.05 g/100 g) than in commercial product (20.79 g/100 g), and their major amino acids were aspartic acid, glutamic acid, leucine, and lysine. The results of sensory evaluation on the taste, color, and flavor showed that product P was superior to commercial product.

• Journal of the Korean Magnetics Society
• /
• v.21 no.5
• /
• pp.157-162
• /
• 2011

The effect of ferrous/ferric molar ratio and precipitants on the formation of nano size magnetite particle was investigated by coprecipitation method. Ferrous sulfate and ferric sulfate were used as iron sources and sodium hydroxide and ammonium hydroxide was used as a precipitant. Single phase magnetite was synthesized with all of experiment conditions (ferrous/ferric molar ratios and precipitants). Particle size was smaller, and particle size distribution was narrower when NaOH was used than $NH_4OH$ was used. The crystallinity and particle size was increased and narrower particle size distribution with increasing molar ratio ferrous/ferric sulfate with the same precipitant. Super paramagnetism could be obtained at all of experiment conditions. The highest saturation magnetization (72 emu/g) was obtained when the ferrous/ferric molar ratio was 2.5 and precipitant was used $NH_4OH$.

• Resources Recycling
• /
• v.31 no.6
• /
• pp.60-65
• /
• 2022

This study presents the carburization process for recycling sludge, which was formed during silicon wafer machining. The sludge used in the carburization process is a mixture of silicon and silicon carbide (SiC) with iron as an impurity, which originates from the machine. Additionally, the sludge contains cutting oil, a fluid with high viscosity. Therefore, the sludge was dried before carburization to remove organic matter. The dried sludge was washed by acid cleaning to remove the iron impurity and subsequently carburized by heat treatment under vacuum to form the SiC powder. The ratio of silicon to SiC in the sludge was varied depending on the sources and thus carbon content was adjusted by the ratio. With increasing SiC content, the carbon content required for SiC formation increased. It was demonstrated that substoichiometric SiC_x (x<1) was easily formed when the carbon content was insufficient. Therefore, excess carbon is required to obtain a pure SiC phase. Moreover, size reduction by high-energy milling had a beneficial effect on the suppression of SiC_x, forming the pure SiC phase.

• Resources Recycling
• /
• v.9 no.5
• /
• pp.28-32
• /
• 2000

In this study, the new processing method to produce magnetite for mono-component black toner was studied using spray roaster. The produced magnetite is compared with TMB 125 made by Magnox, USA. When the weight ratio of the ferrous chloride and the ferric chloride is varied from 3:7~7:3 under $N_2$ atmosphere, the 100% major phase of magnetite is obtained. However, when the content of he ferrous chloride is higher than 70wt%, the content of FeO is increased. The phase of $\Gamma-Fe_2O_3$ is shown in th range of over 70wt% of the ferric chloride. The magnetite produced by spray roasting has a saturation magnetization of 80~85 emu/g and a coercivity of 110~130 Oe. The shape of the particle is irregular sphere and hte size of the magnetite is the range of $0.3~0.5\mu\textrm{m}$. It is shown that the magnetite made by spary roasting is enough to apply to the magnetic material of toner.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.27 no.6
• /
• pp.303-308
• /
• 2017

The $FeCl_3$ waste solution used to etch various metals contains valuable metal such as nickel. In this study, we recovered as high purity nickel carbonate crystalline powders from nickel-containing etching waste solution after regeneration of iron chloride. Firstly we eliminated about of the iron impurities under the condition of pH 4 using 5 % NaOH aqueous solution and then removed the remaining impurities such as Ca, Mn and Zn etc. by using solvent extractant D2EHPA (Di-(2-ethylhexyl) phosphoric acid). Thereafter, nickel carbonate powder having a purity of 99.9 % or more was obtained through reaction with sodium carbonate in a nickel chloride solution.