• 한국세라믹학회지
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• 제55권2호
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• pp.95-107
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• 2018

This presentation will give an overview of Ca-aluminate based biomaterials and their proposed use within the field of nanostructured biomaterials. The paper describes typical features of Ca-aluminate materials with regard to technology, chemistry, biocompatibility including hemocompatibility and bioactivity, and developed microstructure. Special focus will be on the developed microstructure, which is in the nanosize range. Application possibilities within odontology, orthopedics, and drug delivery are presented. The nanostructure including pore size below 5 nm in these structures opens up this material for some use in specific dental-related applications in which antibacterial and bacteriostatic aspects are of importance, and as thin coating on implants within dental and orthopaedic applications. Nanosize porosity is essential in drug delivery systems for controlled release of medicaments. The priority field for Ca-aluminate biomaterials is implant materials, which use minimally-invasive techniques to offer in vivo, on-site developed biomaterials.

• 한국세라믹학회지
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• 제23권3호
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• pp.27-34
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• 1986

The hydration of flyash-$Ca(OH)_2-CaSO_4$.$2H_2O$ system was stuedied with varing mixing ratio of flyahs $Ca(OH)_2$ and caSO4.2H2O The samples were steam-cured for 1-7 days at 9$0^{\circ}C$. The optimum mixing composition was flyash : Ca (OH)2=65:35 with 15% $CaSO_4$.42H_2O$ added which produced the hardened material having the best compressive strength (300kg/$cm^2$) Also the low specific gravity(1, 2) of the hardened paste suggests the possibility that it can be used as a light-weight building material. The added $CaSO_4$.42H_2O$ constituted calcium-sulfo-aluminate hydrates which activates the formation of C-S-H hy-drates. Both hydrates developed the strength of hardened paste. The amount of calcium-sulfo-aluminate hydrates was increased when the $CaSO_4$.42H_2O$ was added over 15% however the increased amount did not help the development of strength because of the individually grown calcium-sulfo-aluminate hydrates.

• 한국구조물진단유지관리공학회 논문집
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• 제24권4호
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• pp.1-9
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• 2020

본 연구는 철근콘크리트 구조물의 염해 내구성 향상의 일환으로써, 보통 포틀랜드 시멘트에 실험체별 다른 비율의 칼슘 알루미네이트 시멘트와 합성 CA₂를 혼입하여 혼입 비율에 따른 염소이온 고정능력을 평가하였다. 침지 후 실험체의 물리·화학적 특성을 압축강도, 공극 구조, 수화물 분석으로 염소이온침투깊이를 EPMA를 통하여 고찰하였다. 클링커 조성에 CA가 34%미만일 경우 실험체의 조밀성이나 강도 발현 양상이 구조재료로서 사용 제한이 없을 것이라고 판단되었으며 CAC와 CA₂를 5:5비율로 혼입하여 실험체에 치환한 실험체가 CAC 혹은 CA₂만 치환한 실험체보다 염소이온 침투억제능력 과 AFm상 및 프리델 염 생성이 높은 것으로 확인할 수 있었다. 결과적으로, 시멘트 페이스트 대비 칼슘 알루미네이트 클링커 치환율이 증가함에 따라 일반적으로 염소이온 고정능력이 향상하였고, CA-CA₂비율에 따라 염소이온 고정 능력 및 염소이온 침투억제 능력에 차이가 있음을 확인할 수 있었다. 실험 범위 내에서 CA-CA₂비율이 39:60이며 시멘트 페이스트 대비 10% 치환한 실험체인 M 10 가 가장 우수한 것으로 나타났다.

• 한국세라믹학회지
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• 제15권4호
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• pp.199-204
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• 1978

In the present investigation, refined alumina obtained from alunite locally available was used as a aluminous source to synthesize monocalcium aluminate $(CA)_3$ the major mineral constituent of alumina cement. The influence of $SiO_2$ and $Fe_2O_3$ contents on the formation of monocalcium aluminate was studied by X-ray diffraction analysis mainly. About 0.8-1.0 of $Al_2O_3/C_3O$ mol ratio and less than 4 percent of $SiO_2$ were desirable for the effective formation of CA. The small amount of alkali and sulphur contents contained in refined alumina from alunite as the impurities were affected to form $C_4A_3S$ and $C_3S_2$, disadvantageous compounds for the alumina cement, therefore the impurities should be restricted in minimum content as possible.

• 한국세라믹학회지
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• 제41권12호
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• pp.933-938
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• 2004

[ $3CaO{\cdot}Al_{2}O_3$ ] 클링커 제조 원료로서의 굴 패각과 정유 폐 촉매의 사용 가능성과 이들 조합물의 클링커 소성성 및 광물 생성거동을 광물상과 미구조 관찰을 중심으로 확인하였다. 굴 패각에 함유된 불순물은 클링커의 합성에 영향을 미치지 않았고 이들 조합물은 비교적 저온에서 $12CaO{\cdot}7Al_{2}O_3$를 생성한 후 다시 CaO와의 반응으로 $3CaO{\cdot}Al_{2}O_3$를 생성하므로 $1400^{\circ}C$에서의 1회 소성으로 클링커 합성이 가능하였다. 그 이상의 온도에서는 분해용융이 진행되었으며 동일한 소성 조건에서 알루미나원으로 수산화알루미늄을 사용할 경우에는 $3CaO{\cdot}Al_{2}O_3$의 생성이 완료되기 전에 용융되어 클링커의 합성이 불가능하였다.

• 한국세라믹학회지
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• 제51권1호
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• pp.37-42
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• 2014

$Mn^{4+}$-doped $CaAl_4O_7$ ($CA_2$) and $CaAl_{12}O_{19}$ ($CA_6$) powders were prepared under different conditions, with changes in the amounts of flux, Mn concentration, and mole ratio of $Al_2O_3$ to $CaCO_3$ in the starting mixtures, which affected the structure and the luminescence. $CA_2:Mn^{4+}$ and $CA_6:Mn^{4+}$ had the same excitation and emission spectra but with different intensities. The excitation spectra exhibited broad bands (320 - 470 nm) centered at 395 nm, while red emission bands were observed at 656 nm. The emission intensity of $CA_6:Mn^{4+}$ was nearly twice as high as that of $CA_2:Mn^{4+}$, as the $Mn^{4+}$ ions were located in an octahedral crystal field in the $CA_6$, but not in the $CA_2$.

• 한국세라믹학회지
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• 제31권4호
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• pp.389-398
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• 1994

Calcium aluminate glasses transmit light at relatively long wavelengths up to 6 ㎛ and exhibit also low Rayleigh scattering values. However they have a tendency to get devitrified easily, which limits their use as routine optical materials. Here, the ternary system CaO-Al2O3-SiO2 glasses with low-silica (<30 mol%) were prepared to prevent the devitrification of CaO-Al2O3 glasses and the properties were investigated as functions of composition. The addition of SiO2 to calcium aluminate glasses promoted their stability, which was due to the decrease of non-bridging oxygens and the reconnection of network. As SiO2 was added, density, refractive index, molar volume of oxygens and thermal expansion coefficient decreased continuously. But the glass transition temperatures with increasing SiO2 contents were raised and then lowered. It was postulated that the anomaly was related to the changes of the middle range order as well as the short range order. As the amount of SiO2 in the glass was increased, the IR cut-off values moved to shorter wavelength owing to 'Si-O' antisymetric stretching vibration. The IR cut-off wavelength of the glasses with 5 and 30 mol% SiO2 was 4.90, 4.55 ㎛, respectively.

• Journal of Periodontal and Implant Science
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• 제32권4호
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• pp.753-767
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• 2002

The purpose of this study was to evaluate histologically the effect of LiF-maleic acid added calcium aluminate(LM-CA) bone cement & CA-PMMA composite bone cement on the healing of calvarial defect in Sprague-Dawley rats. The critical size defects were surgically produced in the calvarial bone using the 8mm trephine bur. The rats were divided in three groups : In the control group, nothing was applied into the defect of each rat. LM-CA bone cement was implanted in the experimental group 1 and CA-PMMA composite bone cement was implanted in the experimental group 2. Rats were sacrificed at 2, 8 weeks after surgical procedure. The specimens were examined by histologic analysis, especially about the bone-cement interface and the response of surrounding tissue. The results are as follows; 1. In the control group, inflammatory infiltration was observed at 2 weeks. At 8 weeks, periosteum and duramater were continuously joined together in the defect area. But the center of defect area was filled up with the loose connective tissue. 2. In the experimental group 1, the bonding between implanted bone cement and the existing bone was seen, which more increased in 8 weeks than 2 weeks. Inflammatory infiltration and the dispersion of implanted bone cement particles were seen in both 2 weeks and 8 weeks. 3. In the experimental group 2, implanted bone itself had a dimensional stability and no bonding between implanted bone cement and the existing bone was seen in both 2 weeks and 8 weeks. Implanted bone cement was encapsulated by fibrous connective tissue. In addition, inflammatory infiltration was seen around implanted bone cement. On the basis of these results, when LM-CA bone cement or CA-PMMA composite bone cement was implanted in rat calvarial defect, LM-CA bone cement can be used as a bioactive bone graft material due to ability of bonding to the existing bone and CA-PMMA can be used as a graft material for augmentation of bone-volume due to dimensional stability.

• 콘크리트학회논문집
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• 제17권6호
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• pp.1011-1018
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• 2005

액상 숏크리트 급결제(알칼리 알루미네이트, 2종의 알카리프리)가 시멘트 계의 수화 특성에 미치는 영향을 조사했다. 새로운 알카리프리계 숏크리트용 급결제(AF2)를 적용할 경우 기존의 알칼리 알루미네이트 급결제에 비해 초결, 종결 시간은 단축되었고, 1일 압축 강도는 유사했다. 12시간 경과된 모르타르 시편의 압축 강도는 알칼리 급결제가 첨가된 시편이 가장 높았으나, 이후 최종 강도는 알칼리 급결제를 첨가한 시편이 가장 낮았다. 그러나 알카리프리가 첨가된 AF1, AE2 시편의 압축 강도는 28일까지 plain과 유사했다. XRD와 DSC 분석을 통해 알칼리계 급결제는 주로 수산화칼슘, 알카리프리계 급결제는 에트링자이트 결정 성장으로 응결이 촉진된 것을 확인했다.

• 콘크리트학회지
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• 제2권4호
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• pp.83-90
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• 1990

최근 개발되어 사용되고 있는 초속경시멘트는 그 조성광물중에 Cakcium-aluminate(11 Cao \ulcorner7Al2O3\ulcornerCaF2) 및 그 수화물이 존재하고 있어 이것들이 산과 극렬반응을 일으켜 시멘트 경화체에 균열과 붕괴현상을 가져온다. 본 연구는 이러한 초속경 시멘트를 사용한 경화체가 Polymet에 의한 개길로 어느 정도의 내산성을 발휘할 수 있는지를 실험한 내용으로 P/C=15 및 20%에서는 다른 시멘트를 사용한 경우와 비슷한 내산성이 있음을 알 수 있었다.