• Journal of the Korean Ceramic Society
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• v.27 no.2
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• pp.179-186
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• 1990

Silicon carbide porous materials used for hot gas filters were prepared using oxide binder. Chamotte, frit and H3PO4 were starting materials to synthesize the oxide binder for high temperature-use. Room temperature bending strength of the silicon carbide porous body was increased with increasing firing temprature or with the amount of the content of frit in the oxide binder. However, in the oxidebinder fired above132$0^{\circ}C$, cristobalite form of AlPO4 phase which undergoes rapid inversion became more prominent with increasing firing time. the average pore size of the silicon carbide filter materials was found to be about one third of the average grain size of the silicon carbide powder used in this study.

• Resources Recycling
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• v.13 no.1
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• pp.54-58
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• 2004

Wollastonite-type glass ceramics were prepared by milling and firing at various temperatures using an automobile waste glass and waste shell as starting materials. Powder mixture ground by disk-type ball mill for 3 hours was pressed into a disk. The pressed specimen was fired at $850^{\circ}C$,$950^{\circ}C$ and $1050^{\circ}C$ for 1 hour in air. From FE-SEM observation, with an increase of the firing temperature from $850^{\circ}C$ to $1050^{\circ}C$, whisker-type phase was grown to about 10 $\mu\textrm{m}$ in length. Specimen fired at $1050^{\circ}C$ showed the formation of well-crystallized whisker-type wollastonite grains and the highest compressive strength.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.570-574
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• 2010

Silver conducting films were formed from nano-sized silver powders and glass frits prepared by flame spray pyrolysis. The mean sizes of the silver powders and glass frits were 73 and 63 nm, respectively. Nano-sized glass frits improved the adhesion strength of the silver conducting film to the glass substrate. The densities of the silver conducting films increased by increasing the glass contents of the films at firing temperatures of 400 and $500{^{\circ}C}$. The specific resistances of the silver conducting films with 5 wt.% glass of silver component were 7.8, 4.2 and 2.4 cm at firing temperatures of 400, 450 and $500{^{\circ}C}$.

• The Korean Journal of Ceramics
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• v.3 no.3
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• pp.195-198
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• 1997

Post-firing process of electronic ceramic, such as electroding and encapsultion with resin, often causes damage by thermal shock. The thermal shock behavior of $BaTiO_3$ ceramics was investigated by the down-quench test, where the relative strength retained is determined after the sample is quenched from an elevated temperature into a fixed temperature bath. The critical temperature drop, $\DeltaTc$, was evaluated for three kinds of sintered $BaTiO_3$ ceramics, which were formed by extrustioin, uniaxial pressing using granules, and uniaxial pressing using powders. A drastic loss in strength caused by microcracking was observed for the specimens quenched with $\DeltaT\geq150^{\circ}C$. This concentp can be adopted as a method of the quality control by monitoring the sudden drop of the strength of capacitor products after each exposure to heat.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.59-60
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• 2011

The purpose of this study is to produce the low-carbon eco-friendly inorganic composite at room temperature by an alkali accelerator without firing process at high temperature, and complement the problem of previous studies, the deterioration in strength caused by cracking, with incorporation of PVA fibers. Results of reviewing the changes in the strength properties of PVA showed that test body mixed with PVA fibers had the superiority in strength expression.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.270-275
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• 2019

Mica capacitor is being adopted for high voltage firing unit of guided weapon system because of its superior impact enduring property relative to ceramic capacitor. Reliability of localized mica high voltage capacitors was verified through environmental test like terminal strength test, humidity test, thermal shock test and accelerated life test for application to high voltage firing unit. Failure mode of mica capacitor is a decrease of insulation resistance and its final dielectric breakdown. Main constants of accelerated life model were derived experimentally and voltage constant and activation energy were 5.28 and 0.805 eV respectively. Lifetime of mica capacitor at normal use condition was calculated to be 38.5 years by acceleration factor, 496, and lifetime at accelerated condition and this long lifetime confirmed that mica high voltage capacitor could be applied for firing unit.

• Journal of Technologic Dentistry
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• v.39 no.3
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• pp.153-159
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• 2017

Purpose: In this study, a corresponding porcelain coating material was applied to dental Co-Cr metal among PFM. Methods: The bonding strength of the fired specimens was measured by a three-point flexural rigidity test. SEM/EDS was used to observe the surface component of specimens. Results: First, All groups were higher than the minimum bonding strength of 25 MPa specified in ISO 9693 for dental metal-ceramics specimens. Second, The bonding strength of control group(WO) is 44.64 MPa. Experimental group DM was 35.45 MPa and DP was 31.82 MPa(P<0.05). Tukey's HSD tests results have shown that the bonding strength in control group(WO) is higher than that of experimental group(DM, DP). Third, In the case of metal - porcelain bonding strength, the application of opaque porcelain and firing were higher than those of the group treated with degassing process. Conclusion: The bonding strength was higher when the powder opaque porcelain was applied than the paste opaque porcelain.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.3
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• pp.111-122
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• 2021

Purpose: The purpose of this in vitro study was to investigate the flexural strength and translucency of three layers in 5Y-ZP and to assess the effect of additional firings on these properties. Materials and Methods: Sintered zirconia blocks were sectioned according to three layers : incisal, transition, and body. Disc-shaped specimens were fabricated from each layer. The diameter of specimens was 15.0 mm and each thickness of specimens for biaxial flexural strength test and translucency was 1.2 mm and 1.0 mm. The specimens were classified into subgroups according to the number of firing (0, 1, and 3 times; n = 10/subgroup) and the additional firings were performed under 900℃ using a furnace. Biaxial flexural strength and translucency was measured using universal testing machine and uv-vis spectrophotometer. X-ray diffraction (XRD) analysis was used for measurement of the phase identification. One-way ANOVA, Tukey HSD test were performed (α = 0.05). Results: There was no significant difference in flexural strength between the three layers (P > 0.05), while there was significant difference in translucency between different layers (P < 0.05). The flexural strength of incisal and transition layer was decreased by the single additional firing, and the three additional firings significantly decreased the flexural strength of three layers. The translucency of layer was decreased by additional firings except the body layer. The XRD patterns of all groups were similar. Conclusion: Three layers of 5Y-ZP were different only in translucency. Additional firings affected the flexural strength and translucency differently depending on the layers but crystalline phases were not changed.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.1
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• pp.130-143
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• 1997

A heat-pressed technique(IPS-Empress, Ivoclar) has been described to construct single unit crown, inlay/onlay and veneers using a partially pre-cerammed and pre-colored glass-leucite ingot that has the greateast strength by the combination of heat-pressed procedure through the smalldiameter sprue and heat treatment procedure. The purpose of this study was to evaluate the flexure strength of a heat-pressed ceramic material(IPS-Empress) without simulated firing treatments according to pontic designs. Two groups of 9 disks(1.4mm thick, 14mm in diameter) each using two types of sprues with different diameters($({\Phi}2.8\;,{\Phi}1.8)$) and numbers were prepared. The specimens were mounted in the testing jig. The flexural strengths were determined, by means of the bi-axial bending test, by loading the center of disk to failure using a universal testing machine(Zwick 145141, Zwick, Germany) at a cross-head speed of 1.0 mm/min. The means flexural strength value of one group using a sprue with ${\Phi}2.8$ was $140.4{\pm}8.0Mpa$. That of the other group using two sprues with ${\Phi}1.8$ was $151.8{\pm}10.3Mpa$. After analysis, results showed that there was a statistical difference between groups(t=2.33m p<0.05). No clnical implications were drawn from these data because of absence of simulated firing treatment.

• Journal of the Korean Ceramic Society
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• v.31 no.9
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• pp.1053-1059
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• 1994

The influence of ZrO2 addition on microstructre and mechanical strength of magnesia ceramics were discussed. ZrO2 was existed as a cubic phase resulted from MgO solubility into ZrO2 on firing at temperature range from 130$0^{\circ}C$ to 1$600^{\circ}C$ for 2 h. The addition of ZrO2 markedly promoted the densification of MgO also above 150$0^{\circ}C$ and the sintered density at 1$600^{\circ}C$, 2 h reached to 95.2% of the theoretical. The solubility of MgO into c-ZrO2 was about 7.68 wt% and it was segregated at grain boundary on cooling to room temperature. ZrO2 existing as a second phase retarded the grain growth of MgO. The bending strength were increased to 240 MPa with the amount of ZrO2.