• 한국광물학회지
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• 제9권1호
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• pp.1-6
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• 1996

Woolastonite from Susan occurs as intercalations in limestone beds of Lower Paleozoic Joseon Supergroup. It is a thermal metamorphic product of impure limestone. Electron microprobe analysis shows that it is considerably pure wollastonite. It has triclinic cell with a=7.932$\AA$, b=7.328$\AA$, c=7.069$\AA$, $\alpha$=89.995$^{\circ}$, $\beta$=$95.255^{\circ}$, and $ \Upsilon=103.367^{\circ}$.Dissolution behaviors of wollastonite have been studied conducting three different dissolution experiments; two different reactions with HC1 (one batch and one re-initialization experiment) and one traction with distilled water. In the batch type powder wollastonite-HCl reaction, pH of solution rapidly increases in the early stage and then its rate of increase slows down to reach plateau resulting in parabolic relationship with time. It is represented by the early rapid rise and fall in pH giving a sharp pH-edge and succeeding slow rise in the re-initialization experiment. The early rapid rise in pH is due to the rapid sorption of H- in solution to oxygens on the reactive surface of wollastonite and the fall in pH means that all reactive surface sites are occupied by H- ions and no more H- adsorption occurs. The slow rise in pH following the pH- edge is due to the dissolution of wollastonite as evidenced by the correlation of pH variation and cation concentration. Dissolution of powder wollastonite in HCl shows linear trend with time. Si is dissolved predominantly over Ca at a constant rate. Ca is dissolved predominantly in the very early stage. Dissolution rate of coarse-grained wollastonite fragments in distilled water is parabolic with times howing a rapid reaction in the early stage and a slow reaction in the advanced stage. The Ca/Si ratio in solution is high in the case of coarse-grained wollastonite fragment as compared with powder wollastonite. The coarse-grained wollastonite fragment-water (acid) reaction resulted in the solution with an elevated constant pH value (alkaline) giving an important significance on the environmental view point.

• Corrosion Science and Technology
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• 제22권4호
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• pp.257-264
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• 2023

Ti-6Al-4V alloys are mainly used as dental materials due to their excellent biocompatibility, corrosion resistance, and chemical stability. However, they have a low bioactivity with bioinertness in the body. Therefore, they could not directly bond with human bone. To improve their applications, their bone bonding ability and bone formation capacity should be improved. Thus, the objective of this study was to improve the bioinert surface of titanium alloy substrate to show bioactive characteristics by performing surface modification using wollastonite powder. Commercial bioactive wollastonite powder was successfully deposited onto Ti-6Al-4V alloy using a room temperature spray process. It was found that wollastonite-coated layer showed homogeneous microstructure and uniform thickness. Corrosion resistance of Ti-6Al-4V alloy was also improved by plasma electrolytic oxidation treatment. Its wettability and bioactivity were also greatly increased by wollastonite coating. Results of this study indicate that both plasma electrolytic oxidation treatment and wollastonite coating by room temperature spray process could be used to improve surface bioactivity of Ti-6Al-4V alloy substrate.

• Smart Structures and Systems
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• 제24권4호
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• pp.541-552
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• 2019

Construction development and greenhouse gas emissions have globally required a strategic management to take some steps to stain and maintain the environment. Nowadays, recycled aggregates, in particular ceramic waste, have been widely used in concrete structures due to the economic and environmentally friendly solution, requiring the knowledge of recycled concrete. Also, one of the materials used as a substitute for concrete cement is wollastonite mineral to decrease carbon dioxide (CO2) from the cement production process by reducing the concrete consumption in concrete. The purpose of this study is to investigate the effect of wollastonite on the mechanical properties and durability of conventional composite concrete, containing recycled aggregates such as compressive strength, tensile strength (Brazilian test), and durability to acidic environment. On the other hand, in order to determine the strength and durability of the concrete, 5 mixing designs including different wollastonite values and recovered aggregates including constant values have been compared to the water - cement ratio (w/c) constant in all designs. The experimental results have shown that design 5 (containing 40% wollastonite) shows only 6.1% decrease in compressive strength and 4.9% decrease in tensile strength compared to the control plane. Consequently, the use of wollastonite powder to the manufacturing of conventional structural concrete containing recycled ceramic aggregates, in addition to improving some of the properties of concrete are environmentally friendly solutions, providing natural recycling of materials.

• 자원리싸이클링
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• 제13권1호
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• pp.54-58
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• 2004

Wollastonite-type glass ceramics were prepared by milling and firing at various temperatures using an automobile waste glass and waste shell as starting materials. Powder mixture ground by disk-type ball mill for 3 hours was pressed into a disk. The pressed specimen was fired at $850^{\circ}C$,$950^{\circ}C$ and $1050^{\circ}C$ for 1 hour in air. From FE-SEM observation, with an increase of the firing temperature from $850^{\circ}C$ to $1050^{\circ}C$, whisker-type phase was grown to about 10 $\mu\textrm{m}$ in length. Specimen fired at $1050^{\circ}C$ showed the formation of well-crystallized whisker-type wollastonite grains and the highest compressive strength.

• 한국토양비료학회지
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• 제6권4호
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• pp.221-226
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• 1973

현(現) 비료(肥料) 공정규격(公定規格)에 보증성분(保證成分)이 미달(未達)되는 규회석(珪灰石)의 비효(肥效) 및 규회석(珪灰石)의 가용(可溶) 규산분석법(珪酸分析法)을 검토(檢討)코져, 가용규산함량(可溶珪酸含量)이 상이(相異)한 수종(數種)의 규회석(珪灰石) 및 규회석(珪灰石)과 가용성규산(可溶性珪酸)을 함유(含有)하지 않은 암석(岩石)의 혼합분말(混合粉末)을 광재(鑛滓)와 대조(對照)하여 벼에 대한 재배시험(栽培試驗)을 수행(遂行)하여 규산(珪酸)의 흡수량(吸收量)을 조사(調査)하고, 공시(供試) 규회석(珪灰石)을 수종(數種)의 완형용액(緩衡溶液)에 침출(浸出)하여 규산가용율(珪酸可溶率)과 식물체(植物體)가 흡수(吸收)한 규산함량(珪酸含量)과 상관관계(相關關係) 및 규회석(珪灰石)의 X-선회절분석(線回折分析)을 하여 다음과 같은 결과(結果)를 얻었다. 1. 가용성(可溶性) 규산함량(珪酸含量)(N/2 HCl)이 높은 규회석(珪灰石)일수록 식물체중의 규산함량 및 흡수량(吸收量)을 증가(增加)시켰다. 2. 광재(鑛滓) 처리구(處理區)의 벼 짚중(中) 규산흡수량(珪酸吸收量)은 가용성(可溶性) 규산함량(珪酸含量)이 4.1%인 규회석분말구(珪灰石粉末區)와 같이 가장 낮았다. 3. 가용성(可溶性) 규산함량(珪酸含量)이 높은 규회석(珪灰石)에 잡석(雜石)을 혼합(混合)하여 시비(施肥)하여도 수도체(水稻體)의 규산함량(珪酸含量)은 동량(同量)의 가용성규산함량(可溶性珪酸含量)을 함유(含有)한 규회석(珪灰石)과 같은 효과이었다. 4. 각종(各種) 완형용액(緩衡溶液)에 침출(浸出)된 가용규산(可溶珪酸)과 짚중(中) 규산함량(珪酸含量) 및 흡수량(吸收量)과는 고도(高度)의 유의성(有意性)이 있는 정(正)의 상관(相關)이었으며 N/2염산(鹽酸) 침출규산(浸出珪酸) 분석법(分析法)도 규회석(珪灰石)의 규산분석법(珪酸分析法)으로써 충분(充分)히 사용(使用)될 수 있는 방법(方法)이었다. 5. 규회석(珪灰石)의 X-선(線) 회절(回折)은 규회석(珪灰石)의 조성(造成)을 찾아낼 수 있으며, 결정(結晶)이 불량(不良)한 규회석(珪灰石) 일수록 가용규산함량(可溶珪酸含量)이 높았다.

• 마이크로전자및패키징학회지
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• 제6권1호
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• pp.11-21
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• 1999

For microelectronic packaging application, the crystallizable glass powder in CaO-$A1_2O_3-SiO_2-B_2O_3$system was mixed with various amounts of alumina inclusions (\approx 4 $\mu \textrm{m}$), and its sintering behavior, crystallization behavior, and dielectric constant were examined in terms of vol% of alumina and the reaction between the alumina and the glass. Sintering of the CASB glass powder alone at $900^{\circ}C$ resulted in full densification (99.5%). Sintering of alumina-filled composite at $900^{\circ}C$ also resulted in a substantial denslfication higher than 97% of theoretical density, In this case, the maximum volume percent of alumina should be less than 40%. XRD analysis revealed that there was a partial dissolution of alumina into the glass. This alumina dissolution, however, did not show the particle growth and shape accommodation. Therefore, the sintering of both the pure glans and the alumina-filled composite was mainly achieved by the viscous flow and the redistribution of the glass. Alumina dissolution accelerated the crystallization initiation time at $1000^{\circ}C$ and hindered the densification of the glass. Dielectric constants of both the alumina-filled glass and the glass-ceramic composites were increased with increasing alumina content and followed rule of mixture. In case of the glass-ceramic matrix composites showed relatively lower dielectric constant than the glass matrix composite. Furthermore, as alumina content increased, crystallization behavior of the glass was changed due to the reaction between the glass and the alumina. As alumina reacted with the glass matrix, the major crystallized phase was shifted from wollastonite to gehlenite. In this system, alumina dissolution strongly depended on the particle size: When the particle size of alumina was increased to 15 $\mu\textrm{m}$, no sign of dissolution was observed and the major crystallized phase was wollastonite.

• 대한치과기공학회지
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• 제21권1호
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• pp.5-14
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• 1999

Glass ceramics for dental crown prosthesis were prepared by crystallization of CaO-MgO-SiO2-$P_2O_5-TiO_2$ glasses. Their crystallization behaviors have been investigated as a function of heattreatment temperature, holding time and chemical composition in relation to mechinical properties. Crystallization peak temperatures were determined by differential thermal analysis(DTA). Crystalline phases and mircostructures of heat-treated sample were determined by the means of powder X-ray diffraction(XRD) and scanning electron microscopy(SEM). The final crystalline phase assemblages and the microstructures of the samples were found to be dependent on glass compositions, heattreatment temperature, and holding time. 1st crystallization peak temperature(TP), affected strongly by apatite, was found to be increased or decreased. From the experiment, the following results were obtained : 1. The crystallization peak temperature($T_P$) formed by apatite increased until adding up to 9wt% $TiO_2$ to base glass composition, then decreased above that. 2. Apatite($Ca_{10}P_6O_{25}$), whitlockite(${\beta}-3CaO-P_2O_5$), $\beta$-wollastonite($CaSiO_3$), magnesium tianate($MaTiO_3$) and diopside(CaO-MgO-$2SiO_2$) crystal phase were precipitated in MgO-CaO-$SiO_2-TiO_2-P_2O_5$ glass system containing 9wt% and 11wt% of $TiO_2$ 3. Vickers hardness of samples increased with increasing heat-treatment temperature and Vickers hardness of S415T9 samples heat-treated at 1075 was approxi-mately 813Kg $mm^{-2}$ as maximum value. 4. Vickers hardness of samples increased due to precipitation of apatite, whitlockite, $\beta$-wollastonite, magnesium titanate, and diopside crystal phases within glass matrix.

• 보존과학회지
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• 제25권4호
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• pp.439-450
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• 2009

접착용 에폭시 수지 L-30과 충전용 에폭시 수지 L-50을 대상으로 활석, 규사, 규회석을 중량비 5, 50, 80, 120, 150% 비율로 혼합하여 첨가제에 따른 에폭시수지의 특성을 고찰하였다. 각 재료의 점도와 색도를 측정하고, 이온크로마토그래피 분석, 주사전자현미경관찰을 실시하였다. 또한 실제 석조문화재 적용 시 안정성을 평가하고자 초음파속도와 압축강도, 접촉각 측정을 실시하였다. 활석을 혼합한 경우 에폭시 몰탈은 낮은 초음파 속도를 보이며, 압축강도는 배합 비율이 높아짐에 따라 감소하는 경향을 보인다. 반면 규회석을 혼합한 에폭시 몰탈의 경우에는 상대적으로 높은 초음파 속도를 보이며, 배합 비율이 높아짐에 따라 강도가 증가하는 경향이 관찰되었다. 이는 석조문화재의 접착 충전제의 물성이 첨가제의 특성, 즉 입도 및 형태에 의해 영향을 받는다고 해석할 수 있다. 따라서 충전제는 수지의 종류는 물론 첨가제의 종류와 특성, 배합비에 따른 특성이 다르므로, 문화재 적용 시에는 이를 고려한 처리제의 선택이 중요하다.

• 한국세라믹학회지
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• 제11권4호
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• pp.25-30
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• 1974

The mixture of quartz powder and slaked lime with plenty water was oscillated in an autoclave and treated hydrothermally under the pressure of 10 kg/$\textrm{cm}^2$ for 8 hours. The main mineral synthesized was confirmed 11$\AA$ tobermorite by the method of X-ray diffraction and selected area electron diffraction. Tobermorite was heat-treated at 40$0^{\circ}C$, 80$0^{\circ}C$ and 100$0^{\circ}C$ for investigation of transformation of morphology and structure. Electron micrographs showed the thin platy structure of synthetic tobermorite with a little of crumpled foil or fibrous semi-crystalline calcium silicate hydrates. No difference in structure was appeared under the temperature of 80$0^{\circ}C$ but tobermorite converted gradually into wollastonite at 800$^{\circ}$~85$0^{\circ}C$. On heating, moulded material from tobermorite hardly shrinks under 80$0^{\circ}C$.

• 한국건축시공학회지
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• 제24권2호
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• pp.181-191
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• 2024

석회석은 시멘트의 주원료로써 90% 이상을 사용하고 있으며, 고온 소성 과정에서 및 석회석의 탈탄산 반응으로 많은 양의 CO₂를 배출한다. 이에 석회석 사용량 저감을 위해 원료를 대체할 수 있는 부산물에 관한 연구들이 진행 중이다. 또한 광물 탄산화는 기체인 CO₂를 탄산염 광물로 전환하는 기술로 산업시설에서 배출되는 CO₂를 포집하여 광물로 저장 및 자원화할 수 있다. 한편, 건설폐기물은 계속적으로 증가하는 추세로, 폐콘크리트는 많은 부분을 차지하고 있다. 폐콘크리트는 파쇄 및 분쇄를 통해 순환골재로써 활용되고 있으나 이때 발생하는 폐콘크리트 미분말은 유효하게 재이용 되지 못하고 대부분 폐기 또는 매립되는 실정이다. 이에 본 연구에서는 폐콘크리트를 석회석 대체재로써 활용하여 광물 탄산화 기술을 적용할 수 있는 이산화탄소 반응경화 시멘트 제조 가능성을 확인하고자 한다. 폐콘크리트 미분말 치환율 및 이산화탄소 반응 경화 시멘트의 주요 광물이 생성되는 조건인 SiO₂/(CaO+SiO₂) 몰비에 따른 광물 분석 결과, 폐콘크리트 미분말 치환율과 SiO₂/(CaO+SiO₂) 몰비가 높을수록 주요 광물인 Pseudowollastonite와 Rankinite 생성량이 증가하였다. 또한 세 가지 SiO₂/(CaO+SiO₂) 몰비에서 공통적으로 폐콘크리트 미분말을 50% 치환한 경우 Gehlenite가 생성되었으며, 생성량 또한 유사하였다. 이는 콘크리트 미분말에 함유하고 있는 Al₂O₃ 성분이 CaO와 SiO₂와 반응하여 Gehlenite가 합성된 것으로 판단된다. Gehlenite의 경우 Pseudowollastonite와 Rankinite와 같이 광물 탄산화를 통해 탄산염 광물인 CaCO₃를 생성하는 산화물로써 이는 Al₂O₃가 함유된 산업부산물을 원료로 사용하는 경우 이산화탄소 반응경화 시멘트의 광물로써 활용이 가능할 것으로 기대한다.