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Jingjing Zhang,Yeong-Min Park,Xing Yan Tan,Mun Ki Bae,Dong Jun Kim,Tae Hwan Jang,Min Su Kim,Seung Whan Lee,김태규 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.6
Pigments with minute particle sizes, such as carbon black (CB) and pigment red 48:2 (P.R.48:2), are the most important types of pigment and have been widely used in many industrial applications. However, minute particles have large surface areas, high oil absorption and low surface energy. They therefore tend to be repellent to the vehicle and lose stability, resulting in significant increases in viscosity or reaggregation in the vehicle. Therefore, finding the best way to improve the dispersion properties of minute particle size pigments presents a major technical challenge. In this study, minute particle types of CB and P.R.48:2 were treated with nitrogen gas plasma generated via radio frequency-plasma enhanced chemical vapor deposition (RF-PECVD) to increase the dispersion properties of minute particles in deionized (DI) water. The morphologies and particle sizes of untreated and plasma treated particles were evaluated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). The average distributions of particle size were measured using a laser particle sizer. Fourier transform infrared spectroscopy was carried out on the samples to identify changes in molecular interactions during plasma processing. The results of our analysis indicate that N2 plasma treatment is an effective method for improving the dispersibility of minute particles of pigment in DI water.
Wei Jin,Jingjing Tan,Jiaxin Yan,Yao Tao,Ningning Yao,Xiaomeng Ruan,Cuijin Pei 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.6
The normative solid-state reaction process was adopted to prepare Li3Mg4NbO8 ceramics with LiF addition. We investigatedthe impacts of LiF additive on the crystal structure, sinterabillity as well as dielectric performance at microwave region of theLi3Mg4NbO8-basic ceramics. XRD analysis confirmed that the addition of LiF to Li3Mg4NbO8 lead to the formation of newphase Li4Mg4NbO8F with cubic rock salt structure. The densified temperature of Li3Mg4NbO8-basic ceramics could beeffectively reduced from 1150 oC to 900 oC with LiF addition. Both the permitivity (εr) and quality factor (Qf) of presentceramics were is closely correlated with the bulk density and cell volume. The 900 oC-sintered Li3Mg4NbO8-basic ceramicsowned excellent chemical compatibility with silver and optimized microwave dielectric performance (εr ~13. 4, Qf ~ 32,400GHz at 9.4 GHz, and temperature coefficient of resonant frequency (τf) ~ -43.0 ppm/℃).
Effects of V2O5 on sinterability and microwave dielectric properties of NaCa4V5O17 ceramics
Guoguang Yao,Yang Li,Jingjing Tan,Cuijin Pei,Yan Zhang,Jia Chen 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.3
The NaCa4V5O17 ceramics owing low sintering temperature had been prepared via conventional solid state reaction methodusing V2O5 as vanadium source. The sinterability, microwave dielectric characterisations and compatibility with Ag wereinvestigated. Pure phase NaCa4V5O17 with triclinic structure was confirmed by Rietveld refinement and Raman spectrum. Thepermittivity (εr) and quality factor (Qxf) values mainly depended on the relative density, whereas the temperature coefficientof resonant frequency (τf) value was closely connected with the tetrahedral distortion of V(1)O4. The NaCa4V5O17 ceramicssintered at 800 oС owned high densification and moderate microwave dielectric performances under 10.7 GHz: εr = 9.5, Q×f= 34,200 GHz, τf = -90.0 ppm/oС, but poor chemical compatibility with Ag paste.