• Advances in materials Research
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• v.13 no.3
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• pp.221-232
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• 2024

Waste tire management and recycling have grown to be significant issues because they bring up a global environmental concern. Thus, turning recycled waste tires into useful products may help tackle the environmental issue. This research aims to study and compare the effect of recycled carbon black (rCB) and commercial carbon black (CB) at certain 15 vol. % of filler loading on the mechanical, thermal, morphology and electrical properties of epoxy/CB composites. For this project, epoxy resin, diethyltoluenediamine (DETDA), recovered carbon black (rCB) and commercial carbon black (CB) graded N330, N550, N660 and N774 were mixed and compared accordingly to the formulation determined. The CB content was dispersed in the epoxy matrix using the mechanical mixing technique. The distribution and dispersion of CB in the epoxy matrix affect the characteristics of the conductive composites. rCB content at 15 vol% was selected at fixed content for comparison purposes due to the optimum value in electrical conductivity results. The flexural strength results followed the sequence of rCB>N774>N660>N550>N330. As for electrical conductivity results, epoxy/N330 exhibited the highest conductivity value, while the others achieved a magnitude of X10^-3 due to the highest external surface area of N330. In terms of thermal stability, epoxy/N330 and epoxy/N774 were slightly more stable than epoxy/rCB.

• Resources Recycling
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• v.30 no.1
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• pp.77-82
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• 2021

Reduction of CO2 emissions is an important issue in the steel industry, and the research on carbon materials that can partially replace cokes is necessary to reduce CO2 emissions. Meanwhile, the biomass fuel contains some fixed carbon, and the carbon content in the biomass can be increased by torrefaction. As one of the biomass fuels, coffee grounds contains about 55 mass% of carbon, and its about 270,000 tons are landfilled and incinerated annually in Korea. In addition, research on the recycling process due to the increase in annual coffee consumption is required. In this study, the effect of temperature on the concentration of fixed carbon in coffee grounds was investigated during torrefaction. Moreover, the effects of mixing ratio of torrefied coffee grounds with cokes on the carbon concentration and dissolution efficiency in the metal sample were investigated.

• Journal of the Korean Ceramic Society
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• v.19 no.2
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• pp.95-100
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• 1982

Instead of barium carbonate, domestic barite was used as the flux in manufacturing theinsulating porcelain. To avoid the problems arising from the decomposition of barite in the body during firing, BaO.$Al_2O_3$ was synthesized at $1300^{\circ}C$ for 5 hours. synthetic BaO.$Al_2O_3$ was mixed with other materials such as kaoline, alumina, clay, dolomite. The RO content (CaO. MgO. BaO) of the batches was varied from range of 4 to 14wt. % at 2wt. % - intervals, and firing temperature was varied from 1280 to 140$0^{\circ}C$-at 4$0^{\circ}C$ intervals The properties such as water absorption, bulk density. mechnical strength, specific resistance, and linear shrinkage were measured. The body containing 12 wt.% of RO content showed the satisfactory for the application in the Fixed Carbon Film Resistor.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.289-301
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• 1995

The effect of Air/$C_3H_8$ gas addition on the compound layer growth of steels nitrocarburised in $NH_3+Air+C_3H_8$ mixed gas atmospheres was investigated. It is considered that amount of residual $NH_3$ was varied according to alternation of Air/$C_3H_8$ mixing ratio and volume content. The compound layer formed from nitrocarburising was composed of ${\varepsilon}-Fe_{2-3}$(C, N) and ${\gamma}^{\prime}-Fe_4$(C, N). According as Air/$C_3H_8$ mixing ratio increased, the superficial content of ${\gamma}^{\prime}-Fe_4$(C, N) within the compound layer was increased, at the same time the growth rate of compound layer and porous layer was increased. In the case of alloy steel at the fixed gas composition, the growth rate of compound layer and porous layer was worse than carbon steel and compound layer phase composition structure primarily consisted of E phase. As the carbon content of materials was increasing in the given gas atmospheres, the growth rate of compound layer and porous layer was increased and the superficial content of ${\varepsilon}-Fe_{2-3}$(C, N) within the compound layer was increased.

• Journal of the Korean Society for Heat Treatment
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• v.15 no.5
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• pp.219-227
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• 2002

This study has been performed to investigate the effect of $CO_2$ content on the growth characteristics of the compound layer, porous layer and corrosion characteristics of carbon steels after gaseous nitrocarburizing in $70%-NH_3-CO_2-N_2$ at $580^{\circ}C$ for 2.5 hrs. The results obtained from the experiment were the thickness of the compound and porous layers increased with increasing $CO_2$ contents. At the same fixed gas composition the thickness of the compound and porous layer increased with increasing carbon content of the specimens. X-ray diffraction analysis showed that compound layer was mainly consisted of ${\varepsilon}-Fe_{2-3}(N,C)$ and ${\gamma}^{\prime}-Fe_4N$ as the increased with $CO_2$ contents in atmosphere, compound layer was chiefly consisted of ${\varepsilon}-Fe_{2-3}(N,C)$ phase. With increasing $CO_2$ content and total flow rate in gaseous nitrocarburizing, the amount of ${\varepsilon}-Fe_{2-3}(N,C)$ phase in the compound layer was increased. The current density of passivity decreased with increasing $CO_2$ content due to the development of porous layer at the out most surface of ${\varepsilon}-Fe_{2-3}(N,C)$.

• Journal of the Korean Ceramic Society
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• v.49 no.6
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• pp.625-630
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• 2012

Highly porous silicon carbide (SiC) ceramics were fabricated from polysiloxane, SiC and carbon black fillers, AlN-$Y_2O_3$ additives, and poly (ether-co-octene) (PEOc) and expandable microsphere templates. Powder mixtures with a fixed PEOc content (30 wt%) and varying SiC filler contents from 0-21 wt% were compression-molded. During the pyrolysis process, the polysiloxane was converted to SiOC, the PEOc generated a considerable degree of interconnected porosity, and the expandable microspheres generated fine cells. The polysiloxane-derived SiOC and carbon black reacted and synthesized nano-sized SiC with a carbothermal reduction during a heat-treatment. Subsequent sintering of the compacts in a nitrogen atmosphere produced highly porous SiC ceramics with porosities ranging from 78 % to 82 % and a flexura lstrength of up to ~7 MPa.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.777-781
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• 2008

In this work, silver nanoparticles-containing polyacrylonitrile (PAN) solutions in N,N-dimethylformamide (DMF) were electrospun to be webs consisting of nanofibers. The inputted voltage and PAN content in the solution were fixed at 15 kV and 10 wt.% in DMF with 10 cm of tip-to-collector distance (TCD). The PAN/Ag nanofiber webs were stabilized by oxidation at 250 ${^{\circ}C}$ for 2 h in air and carbonized at 1000 ${^{\circ}C}$ for 2 h in $N_2$. The resultant diameter distribution and morphologies of the nanofibers were evaluated by scanning electron microscope analysis. The electrochemical behaviors of the nanofiber webs were also observed by cyclic voltammetry tests. It was found that the presence of silver nanoparticles in carbon nanofiber webs led to the increase of specific capacitance and the decrease of fiber diameters.

• Journal of the Korean Wood Science and Technology
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• v.39 no.4
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• pp.281-290
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• 2011

We analyzed the basic characteristics and adsorption property of carbonized materials from thinning byproducts of major Korean wood species for evaluating as charcoal making raw material. Yield of charcoal was decreased with increasing the carbonization temperature for all wood species. Refining degrees was 9.0 at $400^{\circ}C$, 3.3~5.0 at $600^{\circ}C$ and 0 at $800^{\circ}C$, and was no difference among wood species. With increasing the carbonization temperature, the fixed carbon content was also increased, and charcoal from softwoods had more fixed carbon content than that from hardwoods. Specific surface area was increased with increasing the carbonization temperature, softwood charcoal had more specific surface area than that of hardwood. Pinus rigida showed the highest specific surface area. In formaldehyde removal by charcoal, some materials had highest at $600^{\circ}C$ and the others had highest at $800^{\circ}C$. Pinus koraiensis, Qurcus acutissima and MDF showed maximum formaldehyde removal ability at $600^{\circ}C$. Ethylene gas removal ability of charcoal was increased with increasing the carbonization temperature, and the charcoal from Pinus rigida and Robinia pseudoacacia had higher ethylene gas removal ability than the other species.

• Resources Recycling
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• v.32 no.3
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• pp.38-44
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• 2023

Leaching tests were conducted using sulfuric acid and sodium hydroxide solutions to remove impurities from domestic graphite concentrate. As a result of the leaching experiment using sulfuric acid solution and sodium hydroxide solution, respectively, the difference of removal efficiency was insignificant when the concentration of sodium hydroxide or sulfuric acid was 2 mol/L or more. The fixed carbon content increased with increasing the temperature in the sulfuric acid solution leaching, while it remains constant above 150℃ in sodium hydroxide solution. For the repeated sequential leaching tests, the leaching conditions were 2 mol/L NaOH, 200℃, 1 hour in the sodium hydroxide solution leaching and 2 mol/L H₂SO₄, 100℃, 1 hour in the sulfuric acid solution leaching, respectively. When sulfuric acid leaching followed by sodium hydroxide solution leaching was repeated 5 times, the fixed carbon increased to 99.95% and ash content decreased to 0.048%, while the fixed carbon increased to 99.98% and ash content was reduced to 0.018 when sodium hydroxide solution leaching followed by sulfuric acid solution leaching was repeated 5 times.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.38-43
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• 2022

The effect of introducing oxygen functional groups by oxygen plasma treatment of activated carbon on adsorption properties of cesium ions was investigated. During the oxygen plasma treatment, the frequency, power, and oxygen gas flow rates were fixed at 100 kHz, 80 W, and 60 sccm, respectively, while the reaction time was varied. Under the experimental conditions, the amount of cesium ion adsorption increased as the content of oxygen groups on C-O-C and O=C-O bonds increased when the reaction time with oxygen gas was 10 minutes. However, when the reaction time increased to 15 minutes, the oxygen functional group content decreased resulting in the decrease of the adsorbed cesium ion amount. On the other hand, unlike the oxygen content of the surface-treated activated carbon, the specific surface area and pore properties were hardly affected by the oxygen plasma reaction time. As a result, the oxygen plasma-treated activated carbon improved the cesium ion removal rate by up to 97.3% compared to that of the untreated activated carbon. This is considered to be due to the content of oxygen groups on C-O-C and O=C-O bonds introduced on the surface of the activated carbon through oxygen plasma treatment.