Effect of various surface treatments by the sol-gel method on the bond and flexural strengths of zirconia-porcelain

심재훈,홍민호 대한치과재료학회 2022 대한치과재료학회지 Vol.49 No.3

This study investigates the effect of a silica coating using the sol-gel method on the bonding between zirconia and porcelain. The specimens were manufactured by precise machining in accordance with the international standard (ISO 9693:2019) using commercially available zirconia (IPS-E-max-ZirCAD). The specimens were then classified into an untreated group (control), and 50 µm sandblasted, 110 µm sandblasted, 0.5 mol% sol-gel, and 0.25 mol% sol-gel treated groups. The control group was subjected to grinding treatment only, the sandblasted group used aluminum oxide, and the sol-gel group was impregnated with the test solution, dried, and sintered according to the manufacturer’s instructions. The sintered specimen underwent a grinding process, and after being layered on the zirconia specimen using a dedicated mold, it was fired according to the manufacturer's instructions. In this study, the strength was measured using a universal testing machine by applying a load until fracture occurred at the center of the specimen. Comparison of the results for the poor bonding between the initial zirconia and porcelain revealed that the sol-gel groups showed the highest bonding strength. In the absence of silica treatment, the control and 110 µm sandblasted groups showed a significantly lower bonding strength that that of the sol-gel treated groups. The 50 µm sandblasted group showed a slightly higher bonding strength than the control and 110 µm sandblasted groups owing to the rough surface of the 50 µm sandblasted specimens. When a load was continuously applied and the zirconia was finally destroyed, the sol-gel group showed lower flexural strengths (different from the initial strength) owing to the change in the elastic modulus due to silica penetration. The flexural strengths exhibited by the sol-gel treated groups were statistically significantly lower than those of the control and 110 µm sandblasted groups. The remaining three groups showed flexural strengths that did not significantly exceed the manufacturer’s strength value. Thus, when zirconia and porcelain were combined and silica was penetrated by the sol-gel method, the bonding strength increased, but the final flexural strength of zirconia was lowered due to the change in the elastic modulus.

Sol-gel법으로 이산화티탄(TiO₂)을 저온소성 도포시킨 경량골재콘크리트의 아세트알데히드(CH₃CHO) 제거 특성

이승한(Lee Sung Han),여인동(Yeo In Dong),정용욱(Jung Yong Wook),장석수(Jang Suk Soo) 대한토목학회 2011 대한토목학회논문집 A Vol.31 No.2A

최근 대기오염 물질을 제거하기 위하여 TiO₂ 등의 광촉매 재료를 사용한 기능성콘크리트에 대한 연구가 활발히 이루어지고 있다. 이들 연구에서 TiO₂의 흡착은 콘크리트에 직접 혼합하거나, 현탁액을 표면에 직접 도포하는 방법을 사용하고 있다. 이 중 콘크리트에 TiO₂를 직접 혼합하는 방법은 TiO₂의 사용량에 비하여 효능이 떨어져 표면에 직접 도포하는 방법이 많이 이용된다. TiO₂의 표면도포는 광촉매의 활성화와 접착성 증대를 위하여 400℃이상의 고온 열처리를 실시하게 되며, 이는 콘크리트 수회생성물의 탈수 · 수축으로 내부균열을 발생시키는 원인이 되기도 한다. 이에 이 연구에서는 TiO₂의 저온도포가 가능한 Sol-gel법으로 TiO₂를 제조하였으며 펄라이트 사용 경량골재콘크리트에 저온 고정화하여 TiO₂도포 성능을 평가하였다. 또한 펄라이트 입경을 2.5~5.0 ㎜와 5.0 ㎜이상으로 구분하여 펄라이트 입경, TiO₂ 혼입방법과 혼입률 및 시간경과에 따른 CH₃CHO 제거 특성을 검토하였다. 실험결과, Sol-gel법으로 제조한 TiO₂를 120℃에서 저온 도포할 때 XRF 정량분석에서 TiO₂38%, SiO₂ 29%, CaO 18% 순으로 나타나 TiO₂ 도포율은 높게 나타났다. 또한 펄라이트 입경 2.5~5.0 ㎜에서 TiO₂를 저온도포한 경량골재콘크리트의 CH₃CHO 제거 특성은 Sol-gel법으로 제조된 TiO₂를 7% 표면 도포하였을 경우 94%로 나타나 10%를 혼입할 때 72%에 비해 약 20%정도 높게 나타났다. 또한 펄라이트 입경 5.0 ㎜이상에서 TiO₂를 10%로 치환하여 혼합하였을 경우 CH₃CHO 제거율은 69%로 펄라이트 입경 2.5~5.0 ㎜에 대한 72%와 비슷하게 나타나 펄라이트 입경이 CH₃CHO 제거율에 미치는 영향은 크지 않았다. 시간 경과에 따른 CH₃CHO 제거 특성은 전 시험편의 10시간 평균 제거율이 20시간 전체 제거율의 84% 수준으로 나타나 반응 초기에 제거율이 높은 것으로 나타났다. Recently studies on functional concrete with a photocatalytic material such as TiO₂ have actively been carried out in order to remove air pollutants. The absorbtion of TiO₂ from those studies is applied by it being directly mixed into concrete or by suspension coated on the surface. When it comes to the effectiveness, the former process is less than that of the latter compared with the TiO₂ lise. As a result, the direct coating of TiO₂ on materials' surface is more used for effectiveness. The Surface spread of it needs to have a more than 400℃ heat treat done to stimulate the activation and adhesion of photocatalysis. Heat treat consequently leads hydration products in concrete to be dehydrated and shrunk and is the cause of cracking. The study produces TiO₂ used Sol-gel method which enables it to be coated with a low temperature treat, applies it to pearlite using Lightweight Aggregate Concrete fixed with a low temperature treat and evaluates the spread performance of it. In addition to this, the size of pearlite is divided into two types: One is 2.5 ㎜ to 5.0 ㎜ and the other is more than 5.0 ㎜ for the benefit of finding out the removal characteristics of CH₃CHO whether they are affected by pearlite size, mixing method and ratio with TiO₂ and elapsed time. The result of this experiment shows that although TiO₂ produced by Sol-gel method is treated with 120 temperature, it maintains a high spread rate on the XRF(X ray Florescence) quantitative analysis which ranks TiO₂ 38 percent, SiO₂ 29 percent and CaO 18 percent. In the size of perlite from 2.5 ㎜ to 5.0 ㎜, the removal characteristic of CH₃CHO from a low temperature heated Lightweight concrete appears 20 percent higher when TiO₂ with Sol-gel method is spreaded on the 7 percent of surface. In other words, the removal rate is 94 percent compared with the 72 percent where TiO₂ is mixed in 10 percent surface. In more than 5.0 mm sized perlite, the removal rate of CH₃CHO, when TiO₂ is mixed with 10 percent, is 69 percent, which is similar with that of the previous case. It suggests that the size of pearlite has little effects on the removal rate of CH₃CHO. In terms of Elapsed time, the removal characteristic seems apparent at the early stage, where the average removal rate for the first 10 hours takes up 84 percent compared with that of 20 hours.

항균성 Ag-30CaO·70SiO₂ Gel의 MC3T3 세포적합성에 관한 연구

윤금재,류재경,안응모,김윤종,김택남,노인섭,조성백,Yoon, Geum-Jae,Ryu, Jae-Kyung,An, Eung-Mo,Kim, Yun-Jong,Kim, Taik-Nam,Noh, In-Sup,Cho, Sung-Beck 한국재료학회 2014 한국재료학회지 Vol.24 No.12

It is known that bones get damaged by accidents and aging. Since the discovery of Bioglass, various kinds of ceramics have been also found to bond to living bone; some of these ceramics are already being clinically used as bone-repairing materials. In the present study, antibacterial calcium silicate gel ($Ag-30CaO{\cdot}70SiO_2$ gel) was prepared by sol-gel method in order to control the microstructure, which is related to the dissolution rate and induction period of apatite formation in body environment. In addition, biological $Ag-30CaO{\cdot}70SiO_2$ is tested. This was done to impart antimicrobial activity to the $30CaO{\cdot}70SiO_2$. Ag ion was added during sol-gel synthesis to replace the $H_2O$ added during the making of the $30CaO{\cdot}70SiO_2$ gel, which has silver solutions of various concentration. After the sol-gel process, 1N-$HNO_3$ solution was used to wash the gel when synthesizing the gel, in order to maintain the porous structure and remove PEG, water soluble polymers. Then, the apatite forming ability of the sol-gel derived CaO-$SiO_2$ gels was investigated using simulated body fluid (SBF), which had almost the same ion concentration as that of human blood plasma. The gels were analyzed by FT-IR spectroscopy, SEM observation, XRD, and fluorescent microscopy. The apatite was successfully created even after washing the gel; apatite is present in an amorphous state, and was found to affect the concentration of the Ag ion in cells in MC3T3 live & dead assay results. From these results, it is suggested that a good material that can be used to repair defects of nature bone is $Ag-30CaO{\cdot}70SiO_2$ gel.

A Study on the Corrosion Behavior of Magnesium Alloy Sealed with Chemical Conversion Coating and Sol-gel Coating

( Dong Uk Lee ),( Shivshankar Chaudhari ),( Seung Yong Choi ),( Myung Jun Moon ),( Min Young Shon ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.4

Magnesium alloy is limited in the industrial field because its standard electrode potential is -2.363 V vs. NHE (Normal Hydrogen Electrode) at 25 ℃. This high electrochemical activity causes magnesium to quickly corrode with oxygen in air; chemical conversion coating prevents corrosion but causes surface defects like cracks and pores. We have examined the anti-corrosion effect of sol-gel coating sealed on the defected conversion coating layer. Sol-gel coatings produced higher voltage current and smaller pore than the chemical conversion coating layer. The conversion coating on magnesium alloy AZ31 was prepared using phosphate-permanganate solution. The sol-gel coating was designed using trimethoxymethylsilane (MTMS) and (3-Glycidyloxypropyl) trimethoxysilane (GPTMS) as precursors, and aluminum acetylacetonate as a ring-opening agent. The thermal shock resistance was tested by exposing specimens at 140 ℃ in a convection oven; the results showed changes in the magnesium alloy AZ31 surface, such as oxidization and cracking. Scanning electron microscope (FE-SEM) analysis confirmed a sealed sol-gel coating layer on magnesium alloy AZ31. Electrochemical impedance spectroscopy (EIS) measured the differences in corrosion protection properties by sol-gel and conversion coatings in 0.35 wt% NaCl solution, and the potentiodynamic polarization test and confirmed conversion coating with the sol-gel coating show significantly improved resistance by crack sealing.

Morphology and Optical Properties of a Porous Silicon-Doped Sol-Gel Host

M. Naziruddin Khan,A. S. Al Dwayyan,M. Al Hoshan 대한금속·재료학회 2013 ELECTRONIC MATERIALS LETTERS Vol.9 No.5

Porous silicon (PSi) fabricated by a chemical route was successfully separated in 1,4-dioxane and then incorporated in a sol-gel host. The properties of PSi in both solution and a sol-gel environment were investigated using optical techniques, and strong luminescence was observed. The morphology of PSi was similar in solution and the sol-gel, with particles positioned close together. The PSi samples were highly crystalline. Transmission electron microscopy of PSi in solution revealed that the particles were monodisperse and roughly spherical in shape, with a diameter of around 5 nm. The effect of embedding PSi in a sol-gel matrix on its optical properties was investigated. Changes in the photoluminescence peaks of PSi during the phase transition from sol to dried gel were observed. PSi exhibited good photoluminescence stability in the sol-gel matrix, and crack-free sol-gel rods were obtained.

솔젤법에 의해 제작된 $TiO_2$ 솔과 $SiO_2$ 솔의 점도 특성에 대한 분석

유도현,You Do-Hyun 대한전기학회 2005 전기학회논문지C Vol.54 No.12

[$TiO_2$] sol and $SiO_2$ sol were prepared using sol-gel method. As $H_{2}O$/Alkoxide ratios increased, sol had cluster structure and as $H_{2}O$/Alkoxide ratios decreased, sol had linear structure. Gelation time of $TiO_2$ sol was faster than that of $SiO_2$ sol according to the time. In comparison with initial viscosity between $TiO_2$ sol and $SiO_2$ sol, $TiO_2$ sol was highest at $H_{2}O/Ti(OC_{3}H_{7})_{4}=5$, $SiO_2$ sol was almost constant according to $H_{2}O/Si(OC_{2}H_{5})_{4}$ ratios.

Synthesis of organic-inorganic hybrids using alkoxysilane-functionalized polymer precursor via non-hydrolytic Sol-Gel process

김보영,김나혜,김주영 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1

일반적으로 물을 사용하는 Sol-Gel 공정(hydrolytic sol-gel process)은 잔류 용매와 물의 증발로 인하여 하이브리드 합성 구조 제어 및 재현성의 손실을 초래한다. 이러한 문제점을 해결하기 위해 최근에는 물을 사용하지 않는 비가수 Sol-Gel 공정(nonaqueous sol-gel process)을 이용한 연구가 진행되고 있으며, 비가수 Sol-Gel 공정은 분자 수준의 균질성을 통해 개선된 모폴로지를 제공한다. 본 연구에서는 물을 사용하지 않는 비가수 Sol-Gel 공정을 통하여 Alkoxysilane group이 도입된 새로운 형태의 유기 알콕시 실란 전구체를 사용하여 O-I hybrid를 제조하고 물리적 특성을 평가하였다.

뉴트럴레드가 고정화된 다공성 졸-겔 필름을 이용한 고감도 광섬유 pH 센서의 특성

전다영 ( Da Yeong Jeon ),유욱재 ( Wook Jae Yoo ),신상훈 ( Sang Hun Shin ),한기택 ( Ki Tek Han ),박장연 ( Jang Yeon Park ),박병기 ( Byung Gi Park ),조승현 ( Seung Hyun Cho ),이봉수 ( Bong Soo Lee ) 한국센서학회 2012 센서학회지 Vol.21 No.3

In this study, a fiber-optic pH sensor based on a pH sol-gel film is fabricated. The sol-gel film is made by co-polymerizing tetramethoxysilane, trimethoxymethylsilane, ethanol and distilled water. As a pH indicator, a neutral red is immobilized in a thin porous film formed by the sol-gel process. The pH change in a sensing probe gives rise to a change in the color of the pH sol-gel film, and the absorbance of reflected light through the pH sol-gel film is also changed. By using a spectrometer, therefore, the spectra of reflected lights in the sensing probe with different pH values are measured. Also, the relationships between the pH values and the absorbance are analyzed on the basis of the color variations of the pH sol-gel films. In repeated experiments, the fiber-optic pH sensor shows that it has reversibility, a high reproducibility and a wide absorbance change in a pH range from pH 5 to 9. Also, we confirmed that the fabricated pH sol-gel film exhibits a fast response time, little or no pH indicator leaching and a dynamic range of 2.04 dB from pH 5 to 9. Based on the results of this study, a fiber-optic pH sensor can be developed for the pH monitoring in the harsh environments.

졸-겔 필름을 이용한 반사형 광섬유 pH 센서의 개발

유욱재 ( Wook Jae Yoo ),서정기 ( Jeong Ki Seo ),장경원 ( Kyoung Won Jang ),문진수 ( Jin Soo Moon ),한기택 ( Ki Tek Han ),박장연 ( Jang Yeon Park ),이봉수 ( Bong Soo Lee ),조승현 ( Seung Hyun Cho ),허지연 ( Ji Yeon Heo ),박병기 ( B 한국센서학회 2011 센서학회지 Vol.20 No.4

A reflection-type fiber-optic pH sensor, which is composed of a pH sol-gel film, plastic optical fibers, a mirror, a light source and a spectrometer, is developed in this study. As pH indicators, a bromthymol blue, a cresol red and a thymol blue are used, and they are immobilized in the sol-gel films. The emitted light from a light source is guided by a fiber-optic Y-coupler and plastic optical fibers to the pH sol-gel film in a pH sensing probe. The pH change in the sensing probe gives rise to a change in the color of the pH sol-gel film, and the optical characteristic of reflected light through the pH sol-gel film is also changed. Therefore, we have measured the spectra of reflected lights, which are changed according to the color variations of the pH sol-gel films with different pH values, by using of a spectrometer. Also, the relationships between the pH values and the intensities of reflected lights are obtained on the basis of the color variations of the pH sol-gel films.

Hydrogen production by steam reforming of liquefied natural gas (LNG) over mesoporous Ni-Al₂O₃ aerogel catalyst prepared by a single-step epoxide-driven sol-gel method

Bang, Yongju,Seo, Jeong Gil,Youn, Min Hye,Song, In Kyu Elsevier 2012 International journal of hydrogen energy Vol.37 No.2

<P><B>Abstract</B></P> <P>A mesoporous Ni-Al<SUB>2</SUB>O<SUB>3</SUB> aerogel catalyst was prepared by a single-step epoxide-driven sol-gel method and a subsequent supercritical CO<SUB>2</SUB> drying method (NA-ES catalyst). For comparison, a mesoporous Ni-Al<SUB>2</SUB>O<SUB>3</SUB> aerogel catalyst was also prepared by a single-step alkoxide-based sol-gel method and a subsequent supercritical CO<SUB>2</SUB> drying method (NA-AS catalyst). Differences in physicochemical properties and catalytic activities of mesoporous Ni-Al<SUB>2</SUB>O<SUB>3</SUB> aerogel catalysts in the steam reforming of liquefied natural gas (LNG) were investigated. Textural properties of Ni-Al<SUB>2</SUB>O<SUB>3</SUB> aerogel catalysts were affected by the preparation method. Nickel species were highly dispersed in alumina through the formation of nickel aluminate phase in both NA-ES and NA-AS catalysts. However, chemical states of Al atoms in both catalysts were quite different. In addition, nickel species in the NA-ES catalyst exhibited high reducibility and high dispersion compared to those in the NA-AS catalyst. In the steam reforming of LNG, NA-ES catalyst exhibited a better catalytic performance than NA-AS catalyst in terms of LNG conversion and hydrogen yield, although both catalysts showed a stable catalytic performance during the reaction without deactivation behavior. Furthermore, NA-ES catalyst with small average nickel diameter suppressed water-gas shift reaction. Reducibility and dispersion of nickel species served as important factors determining the catalytic performance of the catalysts.</P> <P><B>Graphical abstract</B></P> <P>In the steam reforming of liquefied natural gas (LNG), NA-ES catalyst (a mesoporous Ni-Al<SUB>2</SUB>O<SUB>3</SUB> aerogel catalyst prepared by a single-step epoxide-driven sol-gel method) showed better LNG conversion and hydrogen yield than NA-AS catalyst (a mesoporous Ni-Al<SUB>2</SUB>O<SUB>3</SUB> aerogel catalyst prepared by a single-step alkoxide-based sol-gel method).</P> <P>[DISPLAY OMISSION]</P> <P><B>Highlights</B></P> <P>► Hydrogen was produced by steam reforming of liquefied natural gas (LNG). ► A Ni-Al<SUB>2</SUB>O<SUB>3</SUB> catalyst was prepared by an epoxide-driven sol-gel method (NA-ES). ► A Ni-Al<SUB>2</SUB>O<SUB>3</SUB> catalyst was prepared by an alkoxide-based sol-gel method (NA-AS). ► NA-ES showed higher LNG conversion and hydrogen yield than NA-AS.</P>