• Journal of the Korean Ceramic Society
• /
• v.52 no.6
• /
• pp.395-402
• /
• 2015

The suspension plasma spray (SPS) technique has been used to obtain dense $Y_2O_3$ coatings and to overcome the drawbacks of the conventional air plasma spray (APS). SPS uses suspensions containing micrometer or sub-micrometer sized powders dispersed in liquid media. In this study, microstructure developments and mechanical properties have been investigated as functions of particle size of source material and plasma processing parameters such as plasma power and stand-off distance. The microstructure of the coating was found to be highly related to the particle size and the plasma processing parameters, and it was directly reflected in the hardness and the adhesion strength. When fine powder (BET $16.4m^2/g$) was used as a raw material in the suspension, there was, with increasing stand-off distance, a change from a dense structure with a slightly bumpy surface to a porous structure with a cauliflower-like surface. On the other hand, when a coarse powder (BET $2.8m^2/g$) was used, the coating density was lower, with microscopic splats on the surface. Using fine $Y_2O_3$ powders, the coating layer with an optimum short stand-off distance showed a high hardness of approximately 90% of that of sintered $Y_2O_3$ and an adhesion strength several times higher than that of the coating by conventional APS.

• Journal of the Korean Ceramic Society
• /
• v.45 no.6
• /
• pp.309-319
• /
• 2008

This study evaluates a range of materials that may be used to design prostheses for bone. It is found that nanocrystalline ceramic-polymer composite could be the best material for prosthetic bone with respect to biocompatibility, morphology, chemistry, and compatibility with the piezoelectric and mechanical behavior of long human bones, such as the femur.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.11 no.4
• /
• pp.527-534
• /
• 2023

This paper conducted a study on the application of ceramic materials for bridge bearing that can complement the durability of PTFE, a conventional bridge bearing friction material, and exhibit low coefficient of friction and friction behavior without lubricant. The ceramic material was zirconia (ZrO₂), and the friction behavior was evaluated according to the roughness coefficient. The roughness coefficient was divided into 0.8 and 0.027, and the average coefficient of friction was calculated to be 0.16 under 15 MPa surface pressure. Afterward, ceramic was made into friction material and applied to the bridge bearing, and performance comparison with PTFE bridge bearing was conducted through compression test and friction test. In the compression test, the ceramic and PTFE bridge bearing showed ideal compression behavior depending on the load. No fractures or defects were observed in the ceramic bridg bearing, but lubricant loss was observed in the PTFE bridge bearing. The average coefficient of friction of the ceramic bridge bearing analyzed through friction behavior was 0.16. The inherent material properties of the physical and chemical properties of ceramics, the excellent mechanical properties derived from the performance evaluation, and the coefficient of friction of 0.16 suggest that it can be considered as a friction material.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.332-332
• /
• 2010

We have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films withouWe have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films without a high temperature sintering process. In order to remove the coffee ring effect in the ink drop, we have introduced a co-solvent system in order to create Marangoni flow in the ink drop, which leads to the dense packing of ceramic powders on the substrate during inkjet process. The packing density of the Inkjet-printed $Al_2O_3$ films is around 60% (max. 70%) which is very high compared to the value obtained from the same material films by other conventional methods such as film casting, dip coating process, etc. The voids inside the films (which are around 40% of the entire film volume) are filled with the polymer resin (Cyanate ester) by the infiltration process. This resin infiltration is also implemented by the inkjet printing process right after the Ah03 film ink-jetting process. The microstructures of the printed $Al_2O_3$ films are investigated by Scanning Electron Microscope (SEM) to understand the degree of packing density in the printed films. The inkjet-printed $Al_2O_3$ films have been characterized to investigate its thickness and roughness. Quality factor of the printed $Al_2O_3$ film is also measured to be over 300 at 1MHz.

• Journal of Sensor Science and Technology
• /
• v.31 no.5
• /
• pp.318-323
• /
• 2022

Barium titanate (BaTiO₃) is considered to be a beneficial ceramic material for multilayer ceramic capacitor (MLCC) applications because of its high dielectric constant and low dielectric loss. Numerous attempts have been made to improve the physical properties of BaTiO₃ in response to recent market trends by employing multicomponent alloying strategies. However, owing to its significant number of atomic combinations and unpredictable physical properties, finding a traditional experimental approach to develop multicomponent systems is difficult; the development of such systems is also time-consuming. In this study, 168 new structures were fabricated using special quasi-random structures (SQSs) of Ba_1-xCa_xTi_1-yZryO₃, and 1680 physical properties were extracted from first-principles calculations. In addition, we built an integrated database to manage the computational results, and will provide big data solutions by performing data analysis combined with AI modeling. We believe that our research will enable the global materials market to realize digital transformation through datalization and intelligence of the material development process.

• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.7 s.172
• /
• pp.7-18
• /
• 2005

• 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 Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05c
• /
• pp.23-26
• /
• 2002

In ceramic systems using LTCC, many components including embedded passives and TRL's are used for composition of 3-dimensional circuit. So the exact analysis on this components must be performed. As for the TRL's, material properties including electrical conductivity of metal, loss factor and effective dielectric constant of dielectric material and geometrical factors like roughness of surface, vias, dimension of TRL structure have a large effect on the characteristics of transmission lines. Such properties of materials have different values in each system with ideal ones presented in text book. In this research, the effective material properties in each system are examined and the effect of material properties and geometrical factors on the characteristics of TRL's are analyzed and quantified by simulation and measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.89-92
• /
• 2004

Nowadays, the study on the ceramic components and modules that used in telecommunication system is being performed. The technology that co-fired both a ceramic material and a silver conductor is usually used to develop small telecommunication components and modules. In the study, It is that the lumped elements equivalent circuit with easy tuning control can be matched more accurate at the 50ohm than the transmission line.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1993.05a
• /
• pp.19-21
• /
• 1993

The perovskite type ferroelectrics has been studied to make a flim out of ceramic capacitor with large capacity and miniaturization. In this study. we make a capacitor in small size and high capacity, and measure SEM and dielectric permitivity of BCTM ceramic capacitor.