• Journal of Technologic Dentistry
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• v.35 no.1
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• pp.19-27
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• 2013

Purpose: The aim of this research was to evaluate the shear bond strength of different zirconia veneering ceramics with and without liner glass materials to yttria partially-stabilized tetragonal zirconia polycrystalline(Y-TZP). Methods: Five co mmercial zirconia veneering ceramics were used in this study, E-Max(EM), Creation ZI(CR), Cercon ceram kiss(CE), Triceram(TR) and Zirkonzahn ICE(ZI). All samples were prepared according to manufacturer's instructions. Experimental industrially manufactured Y-TZP ceramic blocks(diameter: 2.7 mm; height: 13.5 mm) were used in this study. Shear bond strength between zirconia ceramic coping and zirconia veneering ceramics were evaluated by the push-shear bond test. The fracture load data were analyzed using ANOVA and Scheffe's test(${\alpha}$=0.05). The fractured surfaces of zirconia core ceraimc and zirconia veneering ceramics were observed using a scanning electron microscope(SEM). Results: The mean shear bond strengths ranged from 20 MPa ($20.12{\pm}6.34$ MPa) to 66.6 MPa ($66.62{\pm}10.01$ MPa). The Triceram(TRG) showed the highest value and Creation ZI(CR) showed the lowest value. In all groups, Zirconia liner and glass material groups was significantly higher shear bond strength than without liner(P<0.05), with the exception of Cercon ceram kiss(CE)groups. Conclusion: Zirconia bonding materials may have the advantage of improved bond strength between zirconia ceramic core and veneering ceramics.

• Journal of the Korean Ceramic Society
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• v.16 no.1
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• pp.21-25
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• 1979

This study is proposed to find an appropriate body for high expansion glass ceramics of ${Na}_2O-{Al}_2O_3-{SiO}_2$ system. The compositions of basic glasses are selected to be melted easily and to be crystallized into nepheline with various contents of alumina. The crystallization temperatures of basic glasses are determined by DTA. The crystals in the basic glasses developed by heat treatment are investigated by X-ray diffraction analysis, and thermal properties such as expansion coefficients, fusion points are measured. We find, therefore,that crystallization temperatures, crystal phases and thermal properties are affected by content of alumina.

• Journal of the Korean Ceramic Society
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• v.29 no.10
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• pp.779-784
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• 1992

In producing cordierite glass-ceramics by sintering, following experiments were conducted in order to determine the optimum heat-treatment schedule for high-crystallinity and dense sintered body. The glass composition of 11.67MgO-29.46Al2O3-52.88SiO2-5P2O5-1B2O3 (wt%) was selected on the basis of the early experiment. The 3-step heat treatment schedule was determined by the results of DTA, Dilatometric measurement and high-temperature XRD, where the particle-size-controlled glass powder was used. The degree of densification and the crystallinity were evaluated by the measurement of the bulk density and X-ray scattering intensity. The specimen fired with the optimum conditions showed ${\alpha}$-cordierite phase, relative density ∼98%, crystallinity ∼92%, thermal expansion coefficient ∼30${\times}$10-7/$^{\circ}C$, dielectric constant ∼5.5 and resistivity ∼1.0${\times}$1012 {{{{ OMEGA }}cm, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.58-60
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• 1988

The dielectric properties of glass ceramics with BaTiO$_3$ crystallites are described. In this study measurements were made over the frequency range 1kHz-10MHz and temperature range $25^{\circ}C$-15$0^{\circ}C$. There are several minor constituents in the glass which needed to obtain the desired properties. The fluorine ion substitutes for oxygen in glass-crystallized BaTiO$_3$. And additions of Mg ion is used to shift the Curie temperature. We show the addition of Mg ion lowers the Curie point to about 323。K.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.301-307
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• 2012

SiAlON glasses are silicates or alumino-silicates, containing Mg, Ca, Y or rare earth (RE) ions as modifiers, in which nitrogen atoms substitute for oxygen atoms in the glass network. These glasses are found as intergranular films and at triple point junctions in silicon nitride ceramics and these grain boundary phases affect their fracture behaviour. This paper provides an overview of the preparation of M-SiAlON glasses and outlines the effects of composition on properties. As nitrogen substitutes for oxygen in SiAlON glasses, increases are observed in glass transition temperatures, viscosities, elastic moduli and microhardness. These property changes are compared with known effects of grain boundary glass chemistry in silicon nitride ceramics. Oxide sintering additives provide conditions for liquid phase sintering, reacting with surface silica on the $Si_3N_4$ particles and some of the nitride to form SiAlON liquid phases which on cooling remain as intergranular glasses. Thermal expansion mismatch between the grain boundary glass and the silicon nitride causes residual stresses in the material which can be determined from bulk SiAlON glass properties. The tensile residual stresses in the glass phase increase with increasing Y:Al ratio and this correlates with increasing fracture toughness as a result of easier debonding at the glass/${\beta}-Si_3N_4$ interface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.396-399
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• 2004

저온 동시소성용 glass-ceramics의 소결 경향성 연구를 위해 lead-borosilicate계 glass를 frit화하여 알루미나분말과 $TiO_2$분말을 $10{\sim}50\;vol%$로 각각 혼합한 후 여러 온도에서 소결하여 소결과 유전 특성을 조사하였다. 그 결과 glass의 연화온도(Ts)가 낮을수록 최대 치밀화 온도가 낮았으며, 반면에 소결밀도는 Ts가 높을수록 높았는데, 이는 glass-ceramicss에서의 결정화도와 관계하였다. 본 연구를 통해 glass-ceramic에서의 소결특성은 glass와 ceramic의 반응성에 의한 2상 석출 정도에 큰 영향을 받음을 알 수 있었으며, ceramic filler로서 알루미나와 $TiO_2$를 이용하여 $900^{\circ}C$에서 소성이 가능하였다. 알루미나의 경우 유전특성$({\epsilon}r=8.5,\;Q{\times}fo=6000)$이 기판용 저유전율 재료로 사용이 가능하였고, $TiO_2$의 경우도 유전특성($({\epsilon}r=17,\;Q{\times}fo=4000)$)이 필터용 고유전율 재료로 사용 가능하도록 높게 나타났다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.311-315
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• 2000

Vanadate glass in the $LiO_2-P_2O_5-Bi_2O_3-V_2O_5$ system containing 10mol% glass fonner, $P_2O_5$ and $Bi_2O_3$ was prepared by melting the batch in pt. crucible followed by Quenching on the copper plate. We found that $LiO_2-P_2O_5-Bi_2O_3-V_2O_5$ glass-ceramics obtained from nucleation of glass showed signifieantly higher capacity and longer cycle life than conventionally made crystalline $LiV_3O_{8}$. In the present paper, we describe the charge / discharge properties during crystallization process and find the best crystallization condition of $LiO_2-P_2O_5-Bi_2O_3-V_2O_5$ glass as cathod material.

• Journal of the Korean Ceramic Society
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• v.40 no.2
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• pp.172-177
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• 2003

Effect of glass addition on the low-temperature sintering and microwave dielectric properties of $BaTi_4O_9$-based ceramics were studied to develop the materials for the functional substrate of low-temperature co-fired ceramics. When 10 wt% of glass was added, sufficient densification was obtained and the relative density more than 98% was reached at the sintering temperature of$875{\circ}C$. The microwave dielectric properties were k=32, Q＊f=9000 GHz, ${ au}_f$=10 ppm/${\circ}C$. As the amount of glass increased, phase decompositions from $BaTi_4O_9;to;BaTi_5O_{11};and;Ba_4Ti_{13}O_{30}$ was observed.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.68.2-68
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• 2000

• Proceedings of the Korean Ceranic Society Conference
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• 2000.10a
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• pp.208.1-208
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• 2000