Kyu-Sung Han

Preparation and characterization of CoAl 2 O 4 blue ceramic nano pigments by attrition milling

Cobalt aluminate () is a highly stable pigment with excellent resistance to light, weather, etc., which has resulted in widespread use as a ceramic pigment. Due to the unique optical characteristics, is generally used as a coloring agent to decorate porcelain products, glass, paints and plastics. Here, pigments were synthesized by polymerized complex method and solid state reaction. Then pigment were grinded using the attrition milling with 1 mm size zirconia ball for 3 hours. The attrition milling process was performed at the constant speed of 800 rpm and ball to powder weight ratio (BPR) was 100 : 1. The characteristics of synthesized pigment were analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), particle size analyser (PSA) and CIE . The XRD patterns of show single phase spinel structure. The particle size of measured by FE-SEM, TEM and PSA analysis was in the range of 100~200 nm. The blue color of obtained pigments could be confirmed through CIE measurement.

Effect of Bi and Zr addition on yellow colour properties of environment-friendly ceria-based pigments

Inorganic pigments have been received a great attention for various applications including paint, glazed ceramic ink, art tile, and building exterior due to their excellent thermal and chemical stability. Traditionally, the compositions of , CdS and CdSe have been widely used as a yellow inorganic pigment. However, the use of these compositions has been restricted in recent years, because they contain harmful elements such as Cd, Cr, Pb and Se. In this study, new environment-friendly ceria-based pigment was synthesized using solid state reaction. Crystal structure and morphology of the obtained yellow pigment were analyzed using XRD and SEM, respectively. Substitutional effect of Zr and Bi on the pigment color was analyzed using UV-vis. spectrophotometer and CIE analysis. The crystal structure of the obtained pigments was dependent on the calcination temperature. The color characteristics and absorption band of the pigments were dependent on the calcination temperature and Zr, Bi contents. As a result, all the obtained yellow pigments showed the effective absorption ranged from ultraviolet to visible light, and (x

High-power Nd3+:glass laser system in KAIST (Sinmyung I)

A high-power Nd 3+ : glass laser system has been constructed and tested. This system consists of a master oscillator, a four-pass amplifier for preamplification, and five-stage amplifiers. The system has been demonstrated in excess of 80 J (2 TW) at 40-ps pulse duration. Final laser beam quality was quite good due to the compensation of the polarization distortion in the four-pass preamplifier, the minimization of the diffraction effect by the image relaying, and the elimination of high spatial frequency components by the spatial filtering. This enables us to obtain high laser output power without any severe spatial spiking effects. Gains and spatial profiles of output pulses were measured after each amplifier stage.

플라이애시 첨가에 따른 세라믹 벽타일 소지의 물성변화

Recently, there have been many efforts to establish suitable processes for recycling fly ash, which is produced in thermal power plants and which poses serious environmental problems. Use of fly ash as a major ingredient of ceramic tiles can increase fly ash utilization, as well as reduce the cost of raw materials in ceramic tile production. In this study, the effects of fly ash addition on ceramic tile properties such as bending strength, water absorption and porosity were investigated. A manufacturing process of ceramic tile was developed for utilization of fly ash with high carbon content. In this approach, it is important to hold the ceramic tiles at a temperature that is sufficient for carbon oxidation, before the pores supplying oxygen to the inside of the ceramic tile are sealed. Ceramic wall tiles were manufactured with 0-40wt% of fly ash addition. The water absorption and porosity of the fired body were slightly changed with increasing fly ash content up to 30wt% and decreased with greater amounts of fly ash addition. The bending strength of ceramic tile including 10wt% fly ash increased, reaching a level comparable to that of ceramic tile without fly ash.

Characterization and synthesis of aqueous pink-red ceramic ink for digital inkjet printing

Ceramic ink-jet printing technology in art tiles, decorated tablewares and other porcelain products has many advantages of fast and precision printing of various images with high efficiency and low cost. For the application to ink-jet printing, ceramic ink requires a stable dispersibility with nano-sized pigments. In this paper, characteristics of pink-red aqueous ceramic ink for ink-jet printing was demonstrated. CaCr0.1Sn0.8SiO5 pigment was synthesized using solid state reaction and deagglomerated using attrition milling. The aqueous ceramic ink contains 10 wt% of the obtained CaCr0.1Sn0.8SiO5 nanopigment with 0.4 wt% of sodium dodecyl sulfate (SDS) as a dispersion agent. Viscosity of CaCr0.1Sn0.8SiO5 aqueous ceramic ink was adjusted using 0.18 wt% of polyvinyl alcohol (PVA) for a suitable jetting from the nozzle. The prepared pink-red ceramic ink showed a good jetting property with formation of a single sphere-shaped droplet after 180 μs without a tail and satellite droplet.

Synthesis and characterization of Y 2 O 3 : Eu 3+ red nano phosphor powders using RF thermal plasma

is an excellent red-emitting phosphor, which has been widely used for display devices due to highly luminescent property and chemical stability. In this study, red phosphors were prepared using the solid state reaction and RF thermal plasma synthesis. The particle size of phosphors obtained by the solid state reaction varied from 10 to , and 30~100 nanometer sized particles were obtained from a liquid form of raw material through RF thermal plasma synthesis without an additional heat treatment. Photoluminescence measurements of the obtained particles showed a red emission peak at 611 nm (). PL intensity of red nano phosphors prepared by RF thermal plasma synthesis was comparable to that of red phosphors prepared by the solid state reaction, indicating that nano-sized red phosphors could be successfully synthesized using one-step process of RF thermal plasma.

Synthesis of carbon nanosheets using RF thermal plasma

An ultrathin sheet-like carbon nanostructure provides an important model of a two-dimensional graphite structure with strong anisotropy in physical properties. As an easy and cheap route for mass production, RF thermal plasma synthesis of freestanding carbon nanosheet from CH (Methane) and C H (Propane) is presented. Using vapor synthesis process with RF inductively thermal plasma, carbon nanosheets were obtained without catalysts and substrates. The synthesized carbon nanosheets were characterized using transmission electron microscopy (TEM), Raman spectroscopy, X- ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. The carbon nanosheets synthesized using methane and propane generally showed 5~6 and 15~16 layers with a wrinkled morphology and size of approximately 100 nm.

Synthesis of high purity carbon powders using inductively thermal plasma

Silicon carbide (SiC) has recently drawn an enormous industrial interest because of its useful mechanical properties such as thermal resistance, abrasion resistance and thermal conductivity at high temperature. Especially, high purity SiC is applicable to the fields of power semiconductor and lighting emitting diode (LED). In this work, high purity carbon powders as raw material for high purity SiC were prepared by a RF induction thermal plasma. Dodecane (C12H26) as hydrocarbon liquid precursor has been utilized for synthesis of high purity carbon powders. It is found that the filter- collected carbon powders showed smaller particle size (10~20 nm) and low crystallinity compared to the reactor-collected carbon powders. The purities of reactor-collected and filter-collected carbon powders were 99.9997 % (5N7) and 99.9993 % (5N3), respectively. In addition, the impurities of carbon powders synthesized by RF induction thermal plasma were mainly originated from the surrounding environment.