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졸-겔법을 이용한 Al₂O₃-CoO 계 박막의 제조와 특성에 관한 연구
심문식(Moon Sik Shim),임용무(Yong Mu Lim) 한국안광학회 1999 한국안광학회지 Vol.4 No.2
This paper reports the preparation and characterization of colored coatings of Al₂O₃,CoO. Films of 25㏖% CoO doped Al₂O₃, have been prepared on soda-lime-silica slide glasses by the sol-gel process from Al-alkoxide and Co-nitrate. The films have been characterized by a photospectroscopy and hardness tester. The color, spectral reflectance and spectral transmittance of the films was expressed in Lab color chart and on spectra plot. Microhardness of the films increased with increasing of the heating temperature. Transmittance and reflectance of the films decreased with increase of the heating temperature and coating times. The coating films showed various light-yellow, deep-yellow, greenish-yellow color as a function of the coating times and heating temperature.
Gd₂O₃-ZrO₂계 고체전해질의 미세구조와 전기전도도
임용무 광주보건대학 2000 論文集 Vol.25 No.-
The zirconia ceramics containing 3~5mol% GdO were sintered at 160℃ for 5h. With additions of less than 10mol% of gadolinia, the sintered zirconia consists of both cubic and monoclinic crystalline phases. During sintering of the zirconia, lots of cracks developed as is typical of non-stabilized zirconia ceramics. But the addition of 15mol% of GdO makes the zirconia stabilized as a cubic phase with lattice parameter a=5.168Å. By two-probe impedance spectroscopy, the Cole-Cole plot for the 15mol%GdO-ZrO measured at 600℃ showed two well separated semicircles. The resistivity of the grain, R and of the grainboundary, R was 148 and 215ohm?㎝, prspectively. The blocking factor a was 0.31. The total eletrical conductivity of 15mol%GdO-ZrO at 1000℃ was 0.15S/㎝, and the activation energy obtained from Arrhenius plot was 0.92eV.
HAp전구체용액의 감압침투법에 의한 Hydroxyapatite 소결체의 미세구조 제어
류영래,임용무 광주보건대학 1998 論文集 Vol.23 No.-
In order to make high density of hydroxyapatite, an infiltration processing was adopted. The HAp precursor solution derived by sol-gel processing was infiltrated into the pre-heated specimen. And the density and the microstructure were experimentally analyzed in accordance with the pre-heating temperature and the infiltration times. The precipitation of the HAp precursor was crystallized in the surface of grains forming open pores through dry and heat treatment. Those showed a pillar shape and an uniaxial crystal growth, wherein remained in a micro-crystal group, after sintering at 1250℃ for 3h. The density of the sintered HAp having no infiltration was 94.3% corresponding to the theoretical density. However, the density thereof was increased from 96.6% for the first infiltration to 96.8% for the third infiltration and was decreased for the more infiltration times. Futhermore, in case of the four times, the average radius and the total volume of the pores of sample pre-heated in 1100℃ were reduced in 1.233Å and 3.26×10^(-3)cc/g, respectively, thereby making it possible to produce the densified hydroxyapatite, relative density 96.8%, by the control of the microstructure, e.g., the removal of the pore and the reduction of the pore volume.
강유전성 BaTiO₃의 분극처리에 의한 유사체액 내에서 Calcium Phosphate 생성
송종은,김은주,황규석,임용무,박영준 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4
Barium titanate (BaTiO3; BTO) has wide application in industry, particularly in the manufacturing of dynamic random access memory chips, electro-optical switches, optical modulators, shutters, optical mixers, and sensors, owing to its ferroelectric and piezoelectric properties after poling treatment. There has recently been considerable interest in the properties of its role in osseointegration. In this study, we investigated the possibility of treating BTO by poling to improve osseointegration by examining the calcium phosphate (Ca-P) crystal growth behavior on the poled and non-poled BTO surfaces in simulated body fluids (SBF). The BTO samples were sintered at 1350℃ for 2 h in air, producing an average grain size of 7 ㎛, which were confirmed by SEM observation. The sintered BTO samples were then polarized (Ep=5 kV/cm) from 160℃ to 25℃ in a Si oil bath for 2 h. The poled and non-poled BTO samples were immersed in 1.5 SBF for 15 days, or 30 days at 37℃. After the immersion period, the morphological and compositional changes of the surface of the immersed BTO specimens were investigated using a field emission scanning electron microscope (FE-SEM) and an energy dispersive X-ray spectrometer (EDX). Qualitative analysis was then performed using fourier transform infrared (FTIR) analysis. Weak and coarse Ca-P crystals had grown on the surface of the non poled BTO, while a marked difference in the Ca-P forming pattern was visible for the poled BTO, showing the negatively charged surface induces a Ca-P layer more easily. We assumed that rapidly adsorbed cations (Ca2+ ions) on the negatively charged surface at the initial stage acted as nuclei for the formation of Ca-P crystals, while no nuclei would be available on the positively charged surface, due to the fact that sodium chloride (NaCl) crystals were formed owing to anion adsorption (Cl ions). In summary, these results demonstrate that poling the ferroelectric BTO surface negatively the possibility of implant osseointegration.