• 한국세라믹학회지
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• 제40권3호
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• pp.255-261
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• 2003

생체활성 유리를 알루미나 기판에 코팅하고 이를 유사 생체 용액에 반응시켰을 때 코팅 유리층 표면에 생성된 수산화 아파타이트 형성 거동 변화에 대하여 연구하였다. 알루미나에 코팅된 생체 활성 유리를 여러 온도에서 열처리하였을 때 다양한 종류의 결정상이 나타났으며, 특히 110$0^{\circ}C$에서 열처리하였을 때는 $\beta$-wollastonite와 apatite, 120$0^{\circ}C$에서 열처리하였을 때는 $\alpha$-wollastonite와 apatite가 생성되었다. 이들 시편을 tris-완충용액에 반응시켰을 때, $\alpha$-wollastonite 결정의 부식 속도가 $\beta$-wollastonite의 부식 속도보다 빨랐다. 그리고 이들 시편을 유사 생체 용액과 반응시켰을 때는 두 코팅층 표면에서 수산화 아파타이트가 형성되었는데, 그 형성 속도는 $\alpha$-wollastonite가 포함된 시편에서 더 빨랐다.

• 한국세라믹학회지
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• 제11권2호
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• pp.31-37
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• 1974

A study was performed to investigate the effect of wollastonite additions with distinguishing from β and α for wollastonite in a mosaic tile body. In this study, the efficiencies by the amounts of additive, maturing conditions and moulding pressure, etc. have been studied mainly with a measurement of thermal analysis, and physical proerties; absorption shore's hardness, linear shringkage, apparent feature and so on. As a result of study, tile body which was contained the wollastonite was reducing the maturing temperature, reducing the absorption ratio, increasing the hardness in propertion to the amounts of wollastonite above the range of 1150°∼1175℃. On the basis of this experiment, the optimum conditions for production species were obtained when wollastonite was added in the range 6%, maturing conditions was operated in the range of 1150°∼1175℃, for 3-4 hrs.

• 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.

• 자원환경지질
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• 제5권4호
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• pp.221-229
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• 1972

Through the series of study on the above subjects, the following were founded. 1. Soluble silica in paddy top-soil (xppm) and maxium possible yield (y) is expressed as following equatic $y=63.97+0.425x-0.00114x^2$ It is known that soluble silica in paddy top-soil in South Korea is limited as 130ppm. 2. Gnder the present Korean condition 90% of paddy-top-soil is estimated to be short in available silica content and the country average to only 78ppm. 3. The total area of Korean paddy-top-soil is about 1,036,710 ha. All requirements of wollastonite in South Korea estimated from the equation $Y=0.94-0.033{\times}$are about 2 million M/T 4. Silicates fertilizer minerals are Bentonite, Zeolite, Wollastonite, Serpentine, and Chlorite. But Wollastonite is most economic and can be supplied to using Korea. 5. Wollastonite is formed in contact metomorphic deposits. Limestone is the country rock of wollastonite. Limestone in Korea is in Ryunchcon system, (Pre-cambrian) Okcheon system, (unknown), Great limestone series (paleozoic), Hongjum series (Paleozoic) and Kyungsang system (mesozoic) so that the zones of these limestone and igneous rock are the possible area which wollastonite can be produced. 6. According to the published geologic map (scale 1/5000), about 25 provinces will be possible area which wollastonite can be produced. In future, I believe that many possible area will be increased. 7. According to this survey at Danyang, total wollastonite resources are about 179,000 M/T and average of soluble $SiO_2$ is 29.84%. 8. According to this survey at Daijeon, total resources are about 57,600 M/T and average of soluble $SiO_2$ is 21.53%. 9. Total wollastonite resources including Danyang, Yangduk, and Daijeon are about 1,172,200 M/T. Considering possible resources, it will be over 20 million M/T and I can say that it is possible to be supply for a score.

• 한국산업보건학회지
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• 제20권4호
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• pp.263-273
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• 2010

Occupational exposure to wollastonite can occur during its mining, processing and using. Wollastonite was analyzed for its physicochemical properties by transmission electron microscope and scanning electron microscope equipped with energy dispersive X-ray spectrometer. Wollastonite fibers were 3.3${\mu}m$ in diameter(av.) and were 30.5${\mu}m$ in length(av.). The atomic composition of wollastonite was Si 56.41% and Ca 43.59%. Respiratory toxicity of wollastonite has been studied in term sequential in Sprague-Dawely rats. UICC chrysotile (average diameter 0.03${\mu}m$, average length 2.93${\mu}m$) was applied as the positive control. The effects of 2mg wollastonite on respiratory system and pathological changes were evaluated after 1, 4, 8, 12 weeks instilled into rat lungs. Inflammation response broke out from 1 week after instilled with wollastonite and the pathological examination further showed increased legions of granulomatous inflammation after 4 weeks, but decreased granulomatous inflammation after 8 weeks, whereas chrysotile induced progressive interstitial granulomatous inflammation and fibrosis as a function of time.

• Elastomers and Composites
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• 제55권4호
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• pp.300-305
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• 2020

In recent times, polymeric foams have been popularly used in various applications. To meet the demand for these applications, polymer foams with excellent mechanical and thermal properties are required. In particular, silicone foam has gained significant attention owing to its superior thermal properties and low density. In this study, the mechanical and thermal properties of silicone foams filled with wollastonite were investigated. A maximum tensile strength of 98.3 kPa was obtained by adding 15 phr of wollastonite. The specific gravity did not exhibit a marked difference up to 10 phr, but it increased substantially above 15 phr wollastonite. Thermogravimetric analysis indicated that adding wollastonite to the silicone foam increased both the amount of residue and the thermal decomposition temperature. The morphologies of the silicone foams filled with wollastonite were observed by scanning electron microscopy.

• 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.

• 한국세라믹학회지
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• 제32권8호
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• pp.893-900
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• 1995

The porous wollastonite ceramics were fabricated after firing calcium silicates, obtained using natural resources and by-products of power plants by hydrothermal synthesis, without organic fibers or asbestos for reinforcement agent. A specimen from diatomite as a SiO2 staring raw material had the highest strength owing to normal grain growth and good densification from homogeneous sperhcial C-S-H hydrates. A specimen from SiO2 sol as a SiO2 starting raw material showed tobermolite, but fly ash and mixed system did xonotlite after hydrothermal synthesis. The specimen from fly ash showed the lowest firing shirikage and strength changes in the firing range from 50$0^{\circ}C$ to 120$0^{\circ}C$. The other phases in all specimens changed to wollastonite phase after firing at 100$0^{\circ}C$. Also the average pore size was distributed from 0.2${\mu}{\textrm}{m}$ to 2${\mu}{\textrm}{m}$.

• 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.

• 한국토양비료학회지
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• 제3권1호
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• pp.23-28
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• 1970

김해(金海) 특이산성(特異酸性) 토양(土壤)(답(畓))에 대(對)한 규회석(珪灰石) 및 $MnO_2$의 효과를 Pot 시험(試驗)으로 실시한 결과(結果) 1. 특이산성토양(特異酸性土壤)(답(畓))에서 문제시(問題視)되는 토양용액(土壤溶液) 중의 Al함량(含量)은 pH의 상승과 더불어 감소되며 이러한 화학적(化學的) 변화(變化)는 규회석(珪灰石)의 시용(施用)으로 더 현저하며 이와 같은 토양(土壤)에 규회석(珪灰石)을 시용(施用)하거나, 혹은 토양(土壤)을 담수상태(湛水狀態)로 하여 토양(土壤)의 pH를 상승시키면 수도(水稻)에 대(對)한 Al해독(害毒)은 문제(問題)가 되지 않으리라 생각 된다. 2. 삼요소(三要素)만을 시용(施用)한 Pot에 생육(生育)한 수도(水稻)가 Fe-toxicity와 유사한 증상을 나타내며 생육(生育)이 부진한 이유(理由)는 식물체(植物體) 중의 Fe와 S의 함량(含量)이 높은데 기인(起因)하며, 규회석(珪灰石)의 시용(施用)으로 식물체(植物體)중의 Fe와 S의 함량(含量)이 현저히 낮아졌고, 또 수도(水稻)의 생육(生育)도 정상적이었다. 3. 토양용액(土壤溶液) 및 식물체(植物體)중의 Fe 함량(含量)은 규회석(珪灰石)의 시용(施用)으로 감소될 수 있기 때문에 특이산성토(特異酸性土)에서 문제(問題)시되는 Fe-toxicity는 규회석(珪灰石)의 시용(施用)으로 피(避)할 수 있다. 4. 규회석(珪灰石)에 병용한 $MnO_2$는 규회석(珪灰石) 단용(單用)보다 식물체(植物體)중의 Fe함량(含量)을 낮추지 못하였다. 5. 규회석(珪灰石)의 시용(施用)은 건물중(乾物重)과 정조수량(精租收量)을 증가(增加)시켰고 규회석(珪灰石)과 병용한 $MnO_2$는 규회석(珪灰石) 단용(單用)보다 수당립수(穗當粒數)와 등숙율(登熟率)을 증가(增加)시켰다. 6. 이상(以上)의 결과(結果)에서 특이산성토(特異酸性土)(답(畓))에 생육(生育)한 수도(水稻)의 생육(生育)이 부진한 주원인(主原因)의 하나가 Fe-toxicity라 생각되며 이와 같은 답토양(畓土壤)에는 규회석(珪灰石)을 시용(施用)하므로서 Fe의 해독작용(害毒作用)을 억제(抑制)할 수 있을 것이다.