• Title/Summary/Keyword: High alumina glass

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Effect of $Al_2O_3$ Particle Size on Thermal Properties of Glass-Ceramics for LTCC Material (저온동시소성용 결정화 유리의 필러 사이즈가 열적 특성에 미치는 영향)

  • Kim, Jin-Ho;Hwang, Seong-Jin;Lee, Sang-Wook;Kim, Hyung-Sun
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2007.11a
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    • pp.281-281
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    • 2007
  • Low Temperature Co-fired Ceramic (LTCC) technology has been used in electronic device for various functions. LTCC technology is to fire dielectric ceramic and a conductive electrode such as Ag or Cu thick film below the temperature of $900^{\circ}C$ simultaneously. The glass-ceramic has been widely used for LTCC materials due to its low sintering temperature, high mechanical properties and low dielectric constants. To obtain the high strength, addition of filler, the microstructure should have various crystals and low pores in a composite. In this study, two glass frits were mixed with different alumina size(0.5, 2, 3.7um) and sintered at the range of $850{\sim}950^{\circ}C$. The microstructure, crystal phases, thermal and mechanical properties of the composites were investigated using FE-SEM, XRD, TG-DTA, Dilatomer. When the particle size of $Al_2O_3$ filler increased, the starting temperatures for the densification of the sintered bodies, onset point of crystallization, peak crystallization temperature in the glass-ceramic composites decreased gradually. After sintered at $900^{\circ}C$, the glass frits were crystallized as $CaAl_2Si_2O_8\;and\;CaMgSi_2O_6$. The purpose of our study is to understand the relationship between the $Al_2O_3$ particle size and thermal properties in composites.

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Microstructure and annealing effect on fracture behavior in the dental glass-infiltrated alumina (치아용 유리침윤 알루미나에서 파괴거동에 미치는 미세구조 및 어닐링 효과)

  • 정종원;최성철
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.10 no.4
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    • pp.330-336
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    • 2000
  • Effects of microstructure and indentation stress on fracture behavior of glass-infiltrated alumina composite for dental restorative application were investigated by the Hertzian and Vickers indentation method. Indentation stress-strain curve of glass-infiltrated alumina has showed the quasi-plastic behavior - deviation from linearity at high stress and the classical Hertzian cone crack, which could be confirmed the subsurface damage micrographs using bonded-interface specimen technique. The indentation stress-strain curves for the starting preforms are strongly dependent on porosity and microstructure of the preforms. On the other hand, the curves for the infiltrated composites are relatively insensitive to these factors. The failure of composite is originated at quasi-plastic deformation region. Damage and fracture behavior due to Hertzian stress field is theoretically examined, so that the indentation stress field plays a great role in material degradation. After Hertzian indentation annealing processing changes fracture behavior of alumina composite, so that stress field in material is healed through annealing.

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Characteristic Analysis of Chemical Compositions for Ancient Glasses Excavated from the Sarira Hole of Mireuksaji Stone Pagoda, Iksan (익산 미륵사지 석탑 사리공 내 출토 고대 유리 유물의 성분특성 분석)

  • Han, Min Su
    • Journal of Conservation Science
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    • v.33 no.3
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    • pp.215-223
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    • 2017
  • The purpose of this study is to reveal the characteristics, correlations, and colorant materials of those using the chemical compositions of 30 glasses excavated from the Sarari hall of the Mireuksaji stone pagoda, and to determine the correlations between them and other glass excavated from the Wanggungri site. The results of the chemical analysis of the 11 glass beads show that they are a soda glass group with high contents of $SiO_2$ and $Na_2O$; these can be further subdivided into soda-alumina groups ($Na_2O-Al_2O_3-CaO-Si_2O$). The characteristics of the stabilizer are classified as being of the high alumina glass group (LCHA), except for two glasses. It was concluded that colorant materials affected the coloring for glass beads by various components including Ti, Mn, Fe, Cu and Pb. In addition, we examined six lead glasses which are glass plate and unknown fragments that are of a common lead glass system ($PbO-SiO_2$) with respect to the average contents of PbO (70wt.%) and $SiO_2$ (30wt.%). As a result of comparing these relics with those of the glass beads excavated by Wanggungri, there is a similarity in that they belong to the soda glass group. However, the contents of $Na_2O$ are relatively higher than that of the glass beads in the Mireuksaji pagoda, and most of relics include glasses with a low content of $K_2O$ and CaO. In addition, the PbO and $SiO_2$ contents are slightly different in the lead glass. It seems that the glass relics made at two different sites may have used different raw materials or techniques.

Study on Characteristics of Porcelain Insulators for High Strength with Alumina Composition (알루미나 조성에 따른 고강도 자기 애자의 특성 연구)

  • 조한구;한세원;박기호;최연규
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.3
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    • pp.353-359
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    • 2004
  • In this study. porcelain insulator samples which have a different alumina composition were manufactured in order to test electrical and mechanical properties and make an analysis of the propagation phenomena of micro cracks on porcelain body. From XRD quantitative analysis the crystalline phases were different with alumina composition, sample C and D which have about l7wt% Corundum phase without the Cristobalite phase shows better electrical and mechanical properties than sample A and B which have the Cristobalite phase. In dielectrics test on porcelain samples with below l7wt% alumina composition, it was found that the amount of glass phase(SiO$_2$) have an main effect to decrease the dielectric loss(tan$\delta$), and the dielectric breakdown voltage of aluminous porcelain insulators was largely affected by its relative density. As a micro tracks analysis, HRB were measured, then the intensity of HRB increased with the amount of alumina composition. On the other hand, the propagation behaviors of cracks was fairly influenced by the distribution of pores.

Characteristics of Carbon Tetrafluoride Plasma Resistance of Various Glasses

  • Choi, Jae Ho;Han, Yoon Soo;Lee, Sung Min;Park, Hyung Bin;Choi, Sung Churl;Kim, Hyeong Jun
    • Journal of the Korean Ceramic Society
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    • v.53 no.6
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    • pp.700-706
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    • 2016
  • Etch rate, surface roughness and microstructure as plasma resistance were evaluated for six kinds of oxide glass with different compositions. Borosilicate glass (BS) was found to be etched at the highest etch rate and zinc aluminum phosphate glass (ZAP) showed a relatively lower etch rate than borosilicate. On the other hand, the etching rate of calcium aluminosilicate glass (CAS) was measured to be similar to that of sintered alumina while yttrium aluminosilicate glass (YAS) showed the lowest etch rate. Such different etch rates by mixture plasma as a function of glass compositions was dependent on whether or not fluoride compounds were formed on glass and sublimated in high vacuum. Especially, in view that $CaF_2$ and $YF_3$ with high sublimation points were formed on the surface of CAS and YAS glasses, both CAS and YAS glasses were considered to be a good candidate for protective coating materials on the damaged polycrystalline ceramics parts in semi-conductor and display processes.

A Comparison in Characteristics of Chemical Composition of Glass Vessels Excavated from Neungsalli Temple in Buyeo, Korea, from Baekje Period

  • Koh, Min Jeong;Kang, Hyung Tae;Kim, Na Young;Kim, Gyu Ho
    • Bulletin of the Korean Chemical Society
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    • v.33 no.12
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    • pp.4173-4179
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    • 2012
  • From Neungsalli Temple located in Buyeo, ancient glass vessel fragments were discovered along with hundreds of glass beads. In this research, we used SEM-EDS to analyze glass vessel fragments and beads excavated from Neungsalli Temple. Then, we analyzed their chemical composition and examined their characteristics. In particular, we investigated a relationship between glass vessels from Neungsalli temple and Hwangnamdaechong (South tomb). The result of our experiment showed that the glass artifacts from Neungsalli temple were all soda glass. To be specific, the vessel fragments were soda-lime glass and spherical beads were high-alumina soda glass. Then, we compared glass vessel fragments from Neungsalli temple to glass vessels excavated from Hwangnamdaechong. Glass vessels from both sites turned out to be soda lime glass. We classified them further based on raw material used for soda - natron and marine plant ash.

Low dielectric mullite/glass composite (저 유전성 Mullite/Glass 복합체에 관한 연구)

  • 백용혁;김주영;강선명
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.6
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    • pp.606-611
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    • 1999
  • Low dielectric Mullite/Glass composites for substrates were fabricated by mullite by synthesized from kaolin and alumina, and borosilicate glass. By the liquid-sintering, the composites were densified at low sintering temperature in air, allowing confiring with Cu, Ag, Au and Ag-Pd. Crystallization of the borosilicate glass was not occurred. The mullite/50 wt% glass composites fired between 950 and $1100^{\circ}C$ showed good properties for high-performed substrate, such as low dielectric constant (5.2~5.4, at 1MHz), low coefficient of thermal expansion (5.3~$5.7{\times}10^{-6}{\cdot}^0C^{-1}$), and bending strength of 130 MPa.

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A Study on the High Strength of porcelain insulators for transmission line (송전용 자기재 현수애자의 고강도 특성 연구)

  • Cho, H.G.;Han, S.W.;Park, K.H.;Choi, Y.K.;Lee, D.I.;Choi, I.H.;Kim, T.Y.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05e
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    • pp.85-88
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    • 2003
  • In this study, porcelain insulator samples which have a different alumina composition were manufactured in order to test electrical and mechanical properties and make an analysis of the propagation phenomena of micro cracks on porcelain body. From XRD quantitative analysis the crystalline phases were different with alumina composition, sample C and D which have about 17wt% Corundum phase without the Cristobalite phase shows better electrical and mechanical properties than sample A and 8 which have the Cristobalite phase. In dielectrics test on porcelain samples with below 17wt% alumina composition, it was found that the amount of glass phase$(SiO_2)$have an main effect to decrease the dielectric loss$(tan{\delta})$, and the dielectric breakdown voltage of aluminous porcelain insulators was largely affected by its relative density. As a micro cracks analysis, HRS were measured, then the intensity of HRS increased with the amount of alumina composition. On the other hand, the propagation behaviors of cracks was fairly influenced by the distribution of pores.

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Characteristics and Classification of Red Brown Glass Beads Excavated in Korean Peninsula (한반도에서 출토된 적갈색 유리구슬의 특성 및 유형 분류)

  • Kim, Na-Young;Kim, Gyu-Ho
    • Journal of Conservation Science
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    • v.29 no.3
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    • pp.279-286
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    • 2013
  • It is characterized and classified as the type of red brown glass beads to compare the chemical composition and manufacturing technique on the 141 samples in 12 sites of the Three Kingdom Period analyzed until now. It can be divided into three types according to the chemical composition of stabilizers(CaO & $Al_2O_3$) and soda raw materials(MgO & $K_2O$) on the red brown glass beads except one sample. Type I of high alumina glass is identified as the most common types that is 78.6 % of the distribution ratio at analytical samples and is excavated the most from ruin sites. In contrast, type II, 13.6 % of distribution ratio at analytical samples, is about 5 % CaO and $Al_2O_3$, MgO and $K_2O$ at around 1.5 % is similar to the composition of plant ash glass. Type III is that the content of CaO is higher than $Al_2O_3$ and the content of MgO and $K_2O$ is below 1.5 %. It is the same as the composition of natron glass and its share is the lowest as 7.9 %. Of these, type III is divided into two types according to the content of MgO and $K_2O$. It is identified that manufacturing technique of type I and II is drawing and type III is casting method with microscopic investigations. Type II and III is estimated that raw materials is different because is confirmed in the majority of ruins in spite of the fact that distribution ratio is very low. So, red brown glass beads distributed in Korea Peninsula are divided into three types of glass culture.

Changing Process of the Glass Beads from Osan Sucheong Site in Gyeonggi-do, Korea (오산 수청동 유적 부장 유리구슬의 전개양상)

  • Lee, Min-hee;Kim, Na-young;Kim, Gyu-ho
    • Journal of Conservation Science
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    • v.33 no.5
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    • pp.331-344
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    • 2017
  • In this study, glass beads from Osan Sucheong were classified according to color into 10 groups. Among these groups, reddish brown, bluish green, and purplish blue were identified as the main colors of glass beads based on their large quantities in Osan Sucheong. The glass beads of these main colors were then classified according to their chemical compositions and and looked at the changing process. Based on the results, reddish brown and bluish green glass beads can both be divided into five types, and purplish blue glass beads can be divided into four types. Furthermore, according to continuity of type, it was identified as the main attributes that the reddish brown beads belong to two types, whereas the bluish green and purplish blue each belong to one type. Based on a review of primary attributes, beads of these three colors were identified as soda glass and high-alumina glass. The results indicate that these beads came from a single, consistent route of origin into the region. However, it is possible that glass beads came through various routes into Osan Sucheong in the $4^{th}$ century, because many types of chemical compositions have been detected for beads from this time.