• 분석과학
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• 제6권2호
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• pp.207-215
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• 1993

소결첨가제($3Al_2O_3{\cdot}5Y_2O_3$, YAG)를 질화규소에 공침방법으로 첨가하여, 통상적인 기계적 혼합 방법으로 준비된 혼합분말에 대한 혼합균일성과 소결 및 기계적 특성을 조사, 비교하였다. 준비된 혼합분말들을 SIMS를 사용하여 분말 표면과 내부의 조성을 비교분석한 결과, 공침법을 사용할 경우 소결첨가제가 $Si_3N_4$ 표면에 피복된 상태로 존재하고 있음을 나타내어 기계적 혼합에 비해 우수한 균일혼합효과를 얻을 수 있음을 확인하였다. 공침법에 의한 균일혼합효과는 $Si_3N_4$ 분말소결체의 소결밀도 및 미세구조의 개선을 수반하여 기계적 강도의 향상을 이룰 수 있음을 확인하였다.

• 한국결정성장학회지
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• 제6권4호
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• pp.558-563
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• 1996

첨가된 소결조제가 다른 $Si_{3}N_{4}/20$ vol% SiC 초미립복합재료의 파괴강도를 측정하였다. 소결조제로서 6 wt% $Y_{2}O_{3}$와 2 wt% $Al_{2}O_{3}$를 사용한 시편의 실온강도는 높았지만 낮은 입계상의 연화온도에 기인하여 급격한 강도저하가 나타났다. 소결조제로서 8 wt% $Y_{2}O_{3}$만을 사용한 시편의 $1400^{\circ}C$에서의 고온강도가 높았는데 이는 높은 입계상 연화온도와 입계유리상의 결정화에 기인하는 것으로 판단하였다.

• 한국산업융합학회 논문집
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• 제23권4_2호
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• pp.669-674
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• 2020

Liquid-phase-sintered (LPS) SiC materials were briefly examined with their microstructure and mechanical property. Especially, effect of high-temperature exposure on the tendency of fracture toughness of LPS-SiC were introduced. The LPS-SiC was fabricated in hot-press by sintering powder mixture of sub-micron SiC and sintering additives of Al₂O₃-Y₂O₃. LPS-SiC represented dense morphology and SiC grain-growth with some amount of micro-pores and clustered additives as pore-filling. The strength of LPS-SiC might affected by distribution of micro-pores. LPS-SiC tended to decrease fracture toughness depending on increasing exposure temperature and time.

• 한국세라믹학회지
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• 제35권8호
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• pp.836-842
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• 1998

In this experiment well-know additives for Mn-Zn ferrites CaO and {{{{ { SiO}_{2 } }} were added at various content and their effects on microstructures and magnetic properties with sintering atmosphere were examined. By adding up to 0.04wt% {{{{ { SiO}_{2 } }} and and 0.06wt% CaO the sintered density was increased and then decreased gra-dually. Higher sintered density and initial permeability were observed by adding both CaO and {{{{ { SiO}_{2 } }} than by adding CaO or {{{{ { SiO}_{2 } }} alone. Without any additives initial permeability and tan$\delta$/${\mu}$ decreased at 1000kHz as oxidation degree(${\gamma}$) increased.

• 연구논문집
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• 통권30호
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• pp.111-119
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• 2000

Y-Si oxide 및 oxynitride를 소결 조제로 첨가하여 질소를 함유하는 액상이 알루미나의 소결에 미치는 영향에 대하여 조사하였다. $1400^{\circ}C$에서 하소된 소결 조제의 주 결정상은 $Y_2$$O_3$와 $SiO_2$의 반응에 의하여 생성된 $\alpha$-$Y_2$ $Y_2$$O_7$이며, N의 함량이 높은 Si-40N은 $\alpha$-$Y_2$$O_3$와 함께 Y-N apatite가 생성된다 소결과정에서 소결 조제로 알루미나의 일부와 반응하여 액상을 형성하며, 알루미나는 액상에 의하여 소결이 촉진된다. SEM으로 미세구조를 관찰한 결과 산화물 소결조제(Si-0N)를 첨가한 알루미나는 균일한 입자성장을 보이지만 oxynitride 소결소재(Si-20N 및 Si-40N)를 첨가한 알루미나는 비정상 입자성장을 일으켜 bimodal 구조를 나타내었으며, N의 함량이 높을수록 비정상 입자성장은 심하게 나타났다. 질소의 함량이 높은 Si-40N 조성의 소결 조제를 첨가한 알루미나는 bloating이 나타나며, 이것은 액상에 녹지 않는 과잉의 질소가 방출되기 때문이다.

• 한국세라믹학회지
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• 제34권6호
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• pp.629-635
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• 1997

The effects of the annealing atmospheres(O2, N2) and sintering additives that Bi2O3 is a major composition on the microwave dielectric and sintering propertie of (1-x)CaTiO3-xLaAlO3 system were investigated. The annealing atmospheres and the increase of annealing time after sintering did not affect the relative dielectric constant($\varepsilon$r) and temperature coefficient of resonant frequency($\tau$f) of (1-x)CaTiO3-xLaAlO3 system. However, the Q.f0 values of (1-x)CaTiO3-xLaAlO3 were very sensitive to annealing atmospheres. As the annealing time increased under O2 atmosphere the Q.f0 values of (1-x)CaTiO3-xLaAlO3 enhanced untill 10 hrs in 0.3$\leq$x$\leq$0.6 region, but degraded over that time. The increasing rate of Q.f0 value increased wth increasing x. On the other hand, as the annealing time increased under N2 atmosphere the Q.f0 values were constant in x$\leq$0.6 region, increased gradually in x$\geq$0.7 region. When 0.97Bi2O3-0.03Al2O3 and 0.76Bi2O3-0.24NiO of 3wt% as sintering additives were added to (Ca0.5La0.5) (Ti0.5Al0.5)O3 (x=0.5) the sintering temperature of 1$600^{\circ}C$ was lowered to 140$0^{\circ}C$, and the relative dielectric constant($\varepsilon$r) and temperature coefficient of resonant frequency($\tau$f) were not nearly changed. The addition of 0.97Bi2O3-0.03Al2O3 and 0.76Bi2O3-0.24NiO of 3wt% to (Ca0.5La0.5)(Ti0.5Al0.5)O3 made the Q.f0 values to be lower about 15% and 34%, respectively.

• 한국세라믹학회지
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• 제35권9호
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• pp.911-916
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• 1998

By using {{{{ { { {Y }_{3 }Al }_{5 }O }_{12 } }} (YAG) and SiO2 as sintering additives the effect of the composition of sintering ad-ditives on microstructure and mechanical properties of the hog-pressed and subsequently annealed SiC ma-terials were investigated. Microstructures of sintered and annealed materials were strongly dependent onthe composition of sintering additives. The average diameter and volume fraction of elongated grains in an-nealed materials increased with the SiO2/YAg ratio while the fracture toughness increased with the SiO2/YAg ratio. The average MPa.{{{{ { m}^{1/2 } }} respectively. Typical strength and fracture toughness of an annealed material with SiO2/YAg ra-tionof 0.67 were 371 MPa and 5.6 MPa.{{{{ { m}^{1/2 } }} respectively.

• The Korean Journal of Ceramics
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• 제1권1호
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• pp.45-54
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• 1995

Four kinds of silicon nitride based ceramic materials have been hot pressed. Effect of the sintering additives on the phase transformation, microstructural development and mechanical properties was investigated. While sintering under the same condition a big difference among the microstructures of the specimens, they appeared alike if sintered to have a similiar $\alpha$-$\beta$ phase ratio. The specimen of the stoichiometric $\alpha$-$\beta$ sialon composition showed very limited amount of the intergranular glassy phase and a significant degree of the residual stress. It exhibited almost no strength degradation up to $1300^{\circ}C$, and the strength of the specimen degraded more as its composition deviated from the stoichiometry.

• 한국세라믹학회지
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• 제44권2호
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• pp.79-83
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• 2007

To fabricate a thick, porous yttria-stabilized zirconia without cracking and warping, a method for the simultaneous control of the porosity and shrinkage was designed. As a pore former, a potato starch was used. For the control of shrinkage the oxidation of Al metal particles was used. For the sintering of the above powder mixtures, a partial sintering technique was used at $1300^{\circ}C$ for 10 min in air. Upon adding the additives, high open porosity above 53% and a low shrinkage level were obtained. As a result cracking and warping of the sintered body were deterred. This outcome most likely resulted from the compensation of sintering shrinkage due to the volume expansion caused by oxidation of the Al metal particles during heat-treatment.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1990년도 추계학술대회 논문집
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• pp.71-77
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• 1990

This paper is studied on the sintering characteristics of Ni-Zn ferrites. The specimen ferrites was composed of 20 mol% NiO, 30mol% ZnO, 50 mol% Fe$_2$O$_3$, and 0.0025 mol%, 0.005 mol%, 0.01 mol% Nb$_2$O$\_$5/, Bi$_2$O$_3$, V$_2$O$\_$5/, wee used as minor additives. Sintering was carried out at 1100$^{\circ}C$. As results from the experiments, the high value of initial permeability of 6X10$^2$∼9X10$^2$ can be achieved at 500KHz∼1000KHz. The value of loss factor 1X10￣$^2$∼2X10$^2$ can be achieved at 500KHz∼1000KHz. The lowest 1/(${\mu}$XQ) value was obtained in the specimen with the addition of 0.005mol% fracyion for V$_2$O$\_$5/.