• Title/Summary/Keyword: Composite ceramic

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BPCR Bonded Partial Ceramic Restoration: A conservative approach

  • Maeng, Myeong-Ho
    • Journal of the Korean Academy of Esthetic Dentistry
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    • v.15 no.2
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    • pp.35-38
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    • 2006

  • A technique is presented through clinical cases for restoring anterior teeth to enhance dental esthetics using bonded partial ceramic restorations (BPCRs) without or with minimum reduction of tooth structures. These restorations offer the advantages of the superior properties of ceramic materials and the conservative nature of a direct composite restoration at the same time.

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Al2O3/Al Composites Fabricated by Reaction between Sintered SiO2 and Molten Al (실리카 소결체와 용융 알루미늄과의 반응에 의한 $Al_2$O$_3$/Al 복합체의 제조)

  • 정두화;배원태
    • Journal of the Korean Ceramic Society
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    • v.35 no.9
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    • pp.923-932
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    • 1998

  • Al2O3/Al composites were produced by displacement reaction method which was carried out by imm-ersing the sintered silica preform which was prepared form fused silica powder in molten aluminu. an ac-tivation energy of 94kJ/mole was calculated from Al-SiO2 reaction data in 1000-130$0^{\circ}C$ temperature range With increase of reaction temperature the alumina particle in the Al2O3/Al composites produced with pur metal Al showed grain growth and the growth of alumina particle in Al2O3/Al composite produced by using of Mg contained Al alloy was inhibited. The flexural strength of Al2O3/Al composites produced at 100$0^{\circ}C$ showed the highest value as 393 MPa. Flexural strength of the composite fabricated at 85$0^{\circ}C$ showed higher deviation than that of the composite produced at above 100$0^{\circ}C$ Low flexural strength of the composite fa-bricated at 120$0^{\circ}C$ due to the growth of pore and alumina particle size. The hardness of composites de-pended on alumina content in Al2O3/Al composite decreased with increasing of aluminium content in case the same alumina content and increased with increasing of silicon content in composite.

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Synthesis and properties of $Al_2O_3-SiC$ Composites from Alkoxides III. Effect of Composite Powder Type on the Sintering Characteristics and Properties of $Al_2O_3-SiC$ Comopsites (알콕사이드로부터 $Al_2O_3-SiC$ 복합재료의 제조 및 특성 III. 복합분말의 형태에 따른 $Al_2O_3-SiC$ 복합재료의 소결 특성 및 물성)

  • 이홍림;김규영
    • Journal of the Korean Ceramic Society
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    • v.30 no.4
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    • pp.316-324
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    • 1993

  • Three types of dispersed, coated and mechanically mixed SiC reinforced Al2O3 composite powders were used to investigate the effect of composite powder type on sintering characteristics and properties of Al2O3-SiC composites. Sinterability of coated type composite powders was superior to that of other composite powders when they were pressureless sintered at 1500~1$700^{\circ}C$ for 2h in Ar atmosphere. However, sinterabilities (>98% TD) of each type of composite powders were similar when they were hot pressed at 180$0^{\circ}C$ for 1h under 30MPa in N2 atmosphere. SiC powders were randomly distributed in the specimen prepared from dispersed type composite powders, whereas homogeneously distributed for coated type specimens. It was found that SiC powders inhibited the grain growth of Al2O3, and fracture toughness was increased by the increment of crack growth resistance due to residual stress by secondary SiC particles within Al2O3 grains.

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The Effect of Nitride Coating on SiC Platelet in $Al_2O_3/SiC$ Hybrid-Composite ($Al_2O_3/SiC$ Hybrid-Composite에서 SiC에 질화물 코팅의 영향)

  • 이수영;임경호;전병세
    • Journal of the Korean Ceramic Society
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    • v.34 no.4
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    • pp.406-412
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    • 1997

  • Al2O3/SiC hybrid-composite has been fabricated by the conventional powder process. The addition of $\alpha$-Al2O3 as seed particles in the transformation of ${\gamma}$-Al2O3 to $\alpha$-Al2O3 provided a homogeneity of the microstructure. The grain growth of Al2O3 are significantly surpressed by the addition of nano-size SiC particles. Dislocation were produced due to the difference of thermal expansion coefficient between Al2O3 and SiC and piled up on SiC particles in Al2O3 matrix, resulting in transgranular fracture. The high fracture strength of the composite was contributed to the grain refinement and the transgranular fracture mode. The addition of SiC platelets to Al2O3/SiC nano-composite decreased the fracture strength, but increased the fracture toughness. Coated SiC platelets with nitrides such as BN and Si3N4 enhanced fracture toughness much more than non-coated SiC platelets by enhancing crack deflection.

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