• Korean Journal of Materials Research
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• v.16 no.9
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• pp.533-537
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• 2006

The effects of binary solvent mixtures with various ratios of toluene and ethanol on the properties of slurries and green sheets were investigated. Viscosity of slurry was changed by varying the ratio of solvent mixture which affected the solubility of binder. The relative solvency behavior of a solvent mixture could be predicted with the Hildebrand solubility parameter(${\delta}$) and hydrogen bonding index( ${\gamma}$). The minimum viscosity, the best dispersion of binder, was reached at the composition of toluene:ethanol=4:6, which corresponded to our forecast. The mechanical properties of green sheets related to evaporation of solvents were influenced by the composition of the solvent mixture. At the azeotrope the skin was formed on a drying cast during the drying process because of fast evaporation. At a range of concentrations over 50wt% toluene, green sheets could not be fully dried at low temperature due to excessive toluene. The mechanical properties of green sheets were excellent at the azeotrope-like composition of toluene:ethanol=4:6 which has a little excess of toluene over the azeotrope.

• Computers and Concrete
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• v.12 no.4
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• pp.553-563
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• 2013

The present study aims to show how the problem of reproducing, as closely as possible, binders of historic mortars by mixing raw materials which are commercially available, can be formulated as a linear optimization problem. The study points out that by mixing five standard raw materials (end-members) it is possible to obtain mortar binders with the almost same chemical compositions of those determined on the historic and archaeological mortar samples studied in some recent scientific papers. An advanced function of the Microsoft Excel spreadsheet, the Solver add-in, was used for the calculation of the right amount of each raw material to be mixed for producing the new binders. This approach could be useful to provide an optimal solution in the process of restoration of ancient monuments, where it is necessary to replace the historic mortars with new highly compatible repair mortars.

• Journal of Powder Materials
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• v.5 no.3
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• pp.199-209
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• 1998

A new low melting inorganic binder, monoclinic $HBO_2$, has been developed for Selective Laser Sintering (SLS) of alumina powder by dehydration process of boron oxide powder in a vacuum oven at $120^{\circ}C$. It led to better green SLS parts and higher bend strength far green and fired parts compared to other inorganic binders such as aluminum and ammmonium phosphate. This appeared to be due to its low viscosity and better wettability of the alumina particle surface. A low density single phase ceramic, aluminum borate ($Al_{18}B_4O_{33}$), and multiphase ceramic composites, $A_{12}O_3-A_{14}B_2O_9$, were successfully developed by laser processing of alumina-monoclinic $HBO_2$ powder blends followed by post-thermal processing; both $Al_{18}B_4O_{33}$ and $A_{14}B_2O_9$ have whisker-like grains. The physical and mechanical properties of these SLS-processed ceramic parts were correlated to the materials and processing parameters. Further densification of the $A_{12}O_3-A_{14}B_2O_9$ ceramic composites was carried out by infiltration of colloidal silica, and chromic acid into these porous SLS parts followed by heat-treatment at high temperature ($1600^{\circ}C$). The densities obtained after infiltration and subsequent firing were between 75 and 80% of the theoretical densities. The bend strengths are between 15 and 33 MPa.

• Tribology and Lubricants
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• v.18 no.5
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• pp.324-332
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• 2002

In order to enhance the thermal stability of binder materials of bonded type solid lubricants, several metal-alkoxide based sol-gel materials such as methyltrimethoxysilane(MTMOS), titaniumisopropoxide$(Ti(Opr^i)_4),$ zirconiumisopropoxide $(Zr(Opr^i)_4)$ and aluminumbutoxide$(Al(Obu^t)_4)$ were chemically modified by epoxy-, acrylic- and fluoro-silane compounds, respectively. Friction and wear characteristics of these hybrid ceramic materials were tested with a micro tribo-tester, and evaluated with respect to both heat-curing temperature and the time. Test results generally showed that hybrid ceramic materials modified by epoxy-silane compounds had a low friction compared to others. And the higher het-curing temperature and the longer heat treatment time resulted in the higher friction and the lower wear. IR spectroscopic analyses revealed that these results were caused mainly by the increased metal oxide content in hybrid ceramics when the heat-curing temperature was over $320^{\circ}C.$

• Journal of Korean Society on Water Environment
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• v.25 no.4
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• pp.515-521
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• 2009

In this study, the applicability of $CaCO_3$ as a seed material for crystallization reaction was tested. $CaCO_3$ was ground to lesser than 425 mesh and was made to media mixed with binder. Batch experiment was to investigate the ${PO_4}^{3-}-P$ removal efficiency of different parameters such as $CaCO_3$ dosage and binder ratio, size, type and mass of media. In addition, the effect of phosphorus removal from wastewater was tested using a lab-scaled crystallization reactor. At the results of the batch test, phosphorus removals were improved with increasing $CaCO_3$ dosage and media mass but were decreased with increasing media size. Moreover, phosphorus removals were influenced by specific surface area but media type. The average T-P and ${PO_4}^{3-}-P$ removal efficiency in a lab-scaled crystallization reactor with $CaCO_3$ media for wastewater were shown to be 60.2% and 60.3% for 18 days of operation time.

• Journal of Powder Materials
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• v.24 no.2
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• pp.147-152
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• 2017

Spherical-type zirconia granules are successfully fabricated by a spray-drying process using a water solvent slurry, and the change in the green density of the granule powder compacts is examined according to the organic polymers used. Two organic binders, polyvinyl alcohol (PVA) and 2-hydroxyethyl methacrylate (HEMA), which are dissolved in a water solvent and have different degrees of polymerization, are applied to the slurry with a plasticizer (polyethylene glycol). The granules employing a binder with a higher degree of polymerization (PVA) are not broken under a uniaxial press; consequently, they exhibit a poor green density of $2.4g/cm^3$. In contrast, the granule powder compacts employing a binder with a lower degree of polymerization (HEMA) show a higher density of $2.6g/cm^3$ with an increase in plasticizer content. The packing behavior of the granule powders for each organic polymer system is studied by examining the microstructure of the fracture surface at different applied pressures.

• Polymer(Korea)
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• v.31 no.5
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• pp.442-446
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• 2007

Alkali soluble and photo-curable polyesters were prepared from fluorene epoxy acrylate and various aromatic dianhydrides. To make a black matrix for LCD color-filter application, photo-resist solution was made by mixing synthesized polyester as binder, carbon black as pigment, initiator and multifunctional monomer in solvent. Black matrix pattern was formed on the glass substrate by lithography process. In this study, we synthesized various polyester-based binder polymers for LCD color-filter applications, and compared the analytical properties of those polymers and lithography patterns.

• Hwankyungkyoyuk
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• v.11 no.2
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• pp.102-117
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• 1998

Responsible environmental behavior of Youths who will live in the 21C needs the ‘Personalization of Environment’, which means the process or the result of awareness to the non-personal environment as the personal environment to show the responsible environmental behaviors through the intended physical and psychological contacts to environment. This study intended to analyze various programs of national parks, zoo, children's garden and Project Learning Tree in the United States and to discuss the possibility of ‘personalization of environment’ and implication for environmental education of Korea. Literature review, field trips, personal interviews and internet searches were used to collect information and data. Programs of North Cascade National Park, Mt. Rainier National Park and 4-H Children's Garden in Michigan State University showed the cases of direct personalization of environment focusing on the direct contact with nature. The programs of Binder Park Zoo in Battle Creek and Project Learning Tree showed the possibilities of indirect personalization of environment forming meaningful relationships with nature through various indirect activities. It is suggested that various natural education programs in Unites States make nature and places meaningful for the people and it needs to be applied for the environmental education programs in Korea.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.839-845
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• 2006

Graphite has hexagonal closed packing structure with two bonding characteristics; (1) van der waals bonding between c axis, and (2) covalent bonding in the a and b axis. The weak van der waals bonds cause self-lubricant property, and the strong covalent bonds cause excellent electric and thermal conductivity. Furthermore, graphite is chemically very inert because of the material composed of only carbon elements. Thus, graphite is very useful for mechanical sealing materials. However, Graphite have porous microstructure because starting materials of graphite produce many volatile during the manufacturing processes. This causes low density of graphite, which is unsuitable for the mechanical sealing materials. Thus, further impregnation process is generally needed to enhance the graphite density. In this work, high density graphite is prepared with the principle of densification when coke and pitch binder, prepared from thermal treatment of coal tar pitch, become dehydrogenation during graphitization or carbonization.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.1
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• pp.40-43
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• 2016

Transparent color coating films were fabricated on a glass substrate by using sol-gel hybrid binder and organic dye. Sol-gel hybrid binder coating film fabricated with PTMS of 0.03 mole showed a very high pencil hardness of 9 H. As the withdrawal speed increased from 1.0 mm/s to 5.0 mm/sec, The yellowness ($b^*$) of coating glass also gradually increased. The transmittance of yellow color coating glass was 82.6% and the haze of coating glass was 0.35%. Red and blue color coating glasses also showed the high transmittance of 62.4% and 80.6% respectively. The surface hardness of color coating films was 6 H.