• Journal of the Korean Ceramic Society
• /
• v.36 no.10
• /
• pp.1123-1131
• /
• 1999

Alumina-glass composites which are considered as the material of the choice for all dental crown was prepared by aqeous-based tape casting and sintering for 2h at 1120$^{\circ}C$ followed by glass infiltration for 2h at 1100$^{\circ}C$ Biaxial strength and fracture toughness of the composites were evaluated to determine the optimum composition of the tape as a function of the amount of constituent such as alumina binder and plasticizer. The strength and the fracture toughness of the alumina tape increased with increasing the contents of alumina and binder. These observations are consistent with in fluence of the constituents on mean alumuna particle distance in tapes suggesting that high strength of the glass infiltrated alumina composites is related to toughening by crack bowing. The biaxial strength and the fracture toughness of the composite containing the optimum constituent composition were 523 MPa and 3.3 MPa$.$1/2 respectively.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2003.07a
• /
• pp.814-817
• /
• 2003

The sintering behavior of $BaO-B_{2}O_{3}-ZnO$, which is Pb-free glass-ceramic system, was examined as functions of the composition and the amount and particle size of $Al_{2}O_{3}$ filler. Different kinds of modifiers were added and $Al_{2}O_{3}$ fillers with different particle sizes ($1.5{\mu}m$ and $4.5{\mu}m$) were added. The glass frit-filler composites were sintered in the temperature range $520{\sim}580^{\circ}C$. X-ray diffraction results revealed that some of the composites crystallized during sintering. Dielectric constant and thermal expansion coefficient the glass-ceramics were analyzed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.8 no.4
• /
• pp.14-19
• /
• 2009

Micro fluid channels are machined on quartz glass using powder blasting, and the machining characteristics of the channels are experimentally evaluated. The powder blasting process parameters such as injection pressure, abrasive particle size and density, stand-off distance, number of nozzle scanning, and shape/size of the required patterns affect machining results. In this study, the influence of the number of nozzle scanning, abrasive particle size, and blasting pressure on the formation of micro channels is investigated. Machined shapes and surface roughness are measured, and the results are discussed. Through the experiments and analysis, LOC are ettectinely machined on quartz glass using powder blasting.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.2
• /
• pp.101-105
• /
• 2016

The basic characteristics of glass are highly fragile and brittle consequences the ultimate purpose of glass manufacturing is to make a transparent glass with complex shape. In order to solve this problem, mechanical properties of glass can be increased by crystallization of its amorphous glass. However, glass-ceramics has become opaque through crystallization process due to the distracted interface of glass by precipitated particles. This study has been investigated thermal processing conditions of LAS transparent glass-ceramic by using DTA (differential thermal analysis), in order to control size of precipitated particle and then fabricate transparent glass-ceramic. DTA indicated that crystallization peak area was declined with increased nucleation temperature. Subsequently, we have been established optimum temperature for crystallization depending on the nucleation temperature. The transmission and thermal expansion were measured after crystallization, and the size of precipitated particle was identified in range of 20~100 nm by FE-SEM. In addition, by setting the optimized crystallization condition, with high transmission and low thermal expansion glass was synthesized through this experiment.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.10a
• /
• pp.213-219
• /
• 2001

In this paper, particle velocity of slurry flow, a kind of solid-particle two phase flow, was measured by using a particle tracking velocimetry. Particles are modeled by sphere-shaped glass whose diameters are 3mm, 5mm, and 7mm At first, a particle which is falling in the water is captured and analyzed to give their free falling velocity. The falling velocity was very high up to about 4m/sec in the air, which needs special algorithm for the accurate measurement. For the upwelling slurry flow in the straight duct, there are some noises caused by cavity. However, the effect was so small that it does not affect the measurement of large particles. From the preliminary study of applying the PTV to measurement of particle movement in slurry flow, we could find out the optimum value of parameters: threshold value., searching area radius and correlation area size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.548-551
• /
• 1999

The cure characteristics of metal particle filled DGEBA/MDA/SN/ zeolite epoxy resin composite system for EMI shielding were investigated by dynamic DSC run method and FT-lR spectroscopy. As the heating rate increased, the peak temperature on dynamic DSC curve increased because of the rapid cure reaction. From the straight line of the Kissinger plot, the curing reaction activation energy and pre-exponential factor could be obtained. As the post-curing time at 15$0^{\circ}C$ increased, the glass increased the glass transition temperature or the thermal stability increased. When the post curing time is too long, the system filled with metallic Al particle can be thermally oxidized by the catalytic reaction of metal filler and the thermal stability of the composite for the EMI shielding application may be decreased.

• Journal of the Korean Ceramic Society
• /
• v.21 no.3
• /
• pp.209-216
• /
• 1984

The influence of the particle size of quartz and the change of cooling rate to the strength of conventional triaxial porcelain was studied, . The results indicate that 1. The residual quartz content was increased by particle size increasing. And the strength was increased by increas-ing residual quartz content which increased the total stress in the specimen. But the influence of residual quartz was lessened by the extent of crack between quartz particle and glass matrix 2. In order to increase the strength of the body fast cooling is suitable to small quartz particle and slow cooling is suitable to large quartz particle.

• Tribology and Lubricants
• /
• v.15 no.1
• /
• pp.46-51
• /
• 1999

An analytical model about lateral crack occurring in abrasive wear of brittle solids is developed. Stress field around the lateral crack and stress intensity factor at the crack tip are analytically modeled. Abrasive wear by abrasive particle is experimentally studied. In soda-lime glass, it is observed that chipping by lateral crack occurs and produces the greatest material removal when normal load applied by the abrasive particle is about 1.5∼3.0 N. The prediction of lateral crack length from the model is compared with the experimentally measured length in soda-lime glass.

• Proceedings of the Optical Society of Korea Conference
• /
• 2003.02a
• /
• pp.10-11
• /
• 2003

Metal nanoparticle doped glasses have various applications such as use as photochromic media for optical disk data storage, the fabrication of optical waveguides and waveguide lasers, use as all-optical switches due to their nonlinear optical properties, as well as use in the color glass recycling industry. Recently, an ultrashort pulsed laser has been used as a powerful tool to make microscopic modifications to transparent Metal nano particle doped glasses. (omitted)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.281-281
• /
• 2007

Low Temperature Co-fired Ceramic (LTCC) technology has been used in electronic device for various functions. LTCC technology is to fire dielectric ceramic and a conductive electrode such as Ag or Cu thick film below the temperature of $900^{\circ}C$ simultaneously. The glass-ceramic has been widely used for LTCC materials due to its low sintering temperature, high mechanical properties and low dielectric constants. To obtain the high strength, addition of filler, the microstructure should have various crystals and low pores in a composite. In this study, two glass frits were mixed with different alumina size(0.5, 2, 3.7um) and sintered at the range of $850{\sim}950^{\circ}C$. The microstructure, crystal phases, thermal and mechanical properties of the composites were investigated using FE-SEM, XRD, TG-DTA, Dilatomer. When the particle size of $Al_2O_3$ filler increased, the starting temperatures for the densification of the sintered bodies, onset point of crystallization, peak crystallization temperature in the glass-ceramic composites decreased gradually. After sintered at $900^{\circ}C$, the glass frits were crystallized as $CaAl_2Si_2O_8\;and\;CaMgSi_2O_6$. The purpose of our study is to understand the relationship between the $Al_2O_3$ particle size and thermal properties in composites.