• 제목/요약/키워드: Al$_2$O$_3$p Particle

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자전연소법으로 제조한 Al2O3.SiC 입자로 보강된2024/(Al2O3.SiC)p 복합재료의 기계적특성 (Mechanical Properties of 2024/(Al2O3.SiC)p Composite Reinforced with Al2O3.SiC Particle Prepared by SHS Process)

  • 맹덕영
    • 한국분말재료학회지
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    • 제7권1호
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    • pp.35-41
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    • 2000
  • Al2O3$.$SiC particle was prepared was prepared by the self-propagting high temperature sYthesis(SHS) process from a mixture of SiO2, Al and C powders, The fabricated Al2O3$.$SiC particle was applied to 2024Al/(Al2O3$.$SiC)pcomposite as a reinforcement. Aluminum matix composites were fabricares by the powder extrusion method using the synthesized Al2O3$.$SiC particle and commercial 2024Al powder. Theoptimum preparation conditions for Al2O3$.$SiC partticle by SHS process were described. The influence of the Al2O3$.$SiC voiume fraction on the mechanical was composite was also discussed. Despite adiabatic temperature was about 2367K, SHs reaction was completed not by itself, but by using pre-heating. Mean particle size of final particle synthesized was 0.73 ${\mu}$m and most of the particle was smaller than 2${\mu}$m. Elastic modulus and tensile strength of the composite increased with increase the volume fraction of reinforcement but, tensile strength depreciated at 30 vol% of reinforcement.

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액상반응에 의한 K+-β"-Al2O3 합성시 분산첨가제 에탄올과 pH가 입도 및 상형성에 미치는 영향 (Effect of Ethanol as a Dispersant and pH on the Particle Size and Phase Formation in the Synthesis of K+-β"-Al2O3 by Solution State Reaction)

  • 조도형;김우성;신재호;임성기
    • 공업화학
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    • 제16권1호
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    • pp.45-51
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    • 2005
  • Aluminum nitrate 수용액을 원료로 사용하여 $K_2O-Li_2O-Al_2O_3$ 3성분계로부터 $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$를 합성하였다. 순수한 $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$의 합성을 위하여 원료물질은 $0.84K_2O{\cdot}0.082Li_2O{\cdot}5.2Al_2O_3$의 조성으로 액상상태에서 혼합되었다. 입자크기를 최소화하고 순수한 $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$를 합성하는데 있어서 분산첨가제와 용액의 pH의 영향을 조사하였다. 분산첨가제로써 에탄올을 0.0~4.0 M 첨가하였고 용액의 pH는 $NH_4OH$ 수용액과 $HNO_3$를 이용하여 조절하였다. 시료는 pH 1.0에서 7.5까지 0.5 간격으로 수집하였다. 각 시료들은 $1200^{\circ}C$에서 2 h 동안 하소한 후 XRD와 PSA 분석을 하였다. 용액의 pH는 입자크기와 상형성에 모두 중요한 영향을 미친 반면, 에탄올의 첨가는 입자크기에만 영향을 주었다. pH 조절에 $HNO_3$를 사용하였을 경우, $HNO_3$를 사용하지 않았을 때 보다 순수한 $K^+-{\beta}^{{\prime}{\prime}}-Al_2O_3$ 상을 합성하는데 유리함을 알 수 있었다.

Al2(SO4)3 용액의 가수분해에 의해 얻어진 Aluminum Hydroxides Gel의 pH가 판상 α−Al2O3의 결정성장에 미치는 영향 (Effect of pH of Aluminum Hydroxides Gel Obtained by Hydrolysis of Al2(SO4)3 Solution on Crystal Growth of α−Al2O3)

  • 최동욱;박병기;한명완
    • 한국세라믹학회지
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    • 제44권10호
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    • pp.562-567
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    • 2007
  • To precipitate the complex gels of the pH 6, 7, 8, 9 included in a flux and an aluminum hydroxides gel, an aqueous solution of a mixture of $Na_2CO_3\;and\;Na_2PO_4{\cdot}12H_2O$ was added with stirring in an aqueous solution of a mixture of $Al_2(SO_4){_3}{\cdot}18H_2O,\;Na_2SO_4\;and\;K_2SO_4$, and then the complex gels were aged in 20 h at $90^{\circ}C$. As the hydrolysis pH changed, it had an effect on the physical properties such as the crystal structure, crystal morphology and a phase transition temperature of the AlO(OH) gel, and also on the crystal structure, crystal morphology, particle size and particle size distribution of the ${\alpha}-Al_2O_3$ platelets prepared by molten-salt precipitation. Also, in this study, the complex gels were crystallized at $1,200^{\circ}C$ and thereafter dried at $110^{\circ}C$, and then it was investigated to effect of the hydrolysis pH on the crystal structure, morphology and particle size distribution of the ${\alpha}-Al_2O_3$ platelets crystals using XRD, DTA, SEM and particle size analyzer.

용탕단조한 AC4A $Al/Al_2O_3+SiC_p$ 하이브리드 금속복합재료의 미세조직과 기계적 성질 (Microstructure of Squeeze Cast AC4A $Al/Al_2O_3+SiC_p$ Hybrid Metal Matrix Composite)

  • 김민수;조경목;박익민
    • 한국주조공학회지
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    • 제14권3호
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    • pp.258-266
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    • 1994
  • AC4A $Al/Al_2O_3+SiC_p$ hybrid composites were fabricated by the squeeze infiltration technique. Effect of applied pressure, volume fraction of reinforcement($Al_2O_3$ and SiC) and SiC particle size($4.5{\mu}m$, $6.5{\mu}m$ and $9.3{\mu}m$) on the solidification microstructure of the hybrid composites were examined. Mechanical properties were estimated preliminarly by fractographic observation, hardness measurement and wear test. Results show that the microstructure of the hybrid composites were quite satisfactory, namely revealing relatively uniform distribution of reinforcements and refined matrix. Some aggregation of SiC particle caused by particle pushing was observed especially in the hybrid composites containg in fine particle($4.5{\mu}m$). Refined matrix was attributed to applied pressure and increased nucleation sites with addition of reinforcements. Fractured facet also revealed finer for the hybrid composites possibly due to refined matrix. Hardness and wear resistance increased with volume fraction of reinforcements. For hybrid composites with $9.3{\mu}m$ SiC, hardness was somewhat lower and wear resistance higher than other composites.

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The effect of repeated surface treatment of zirconia on its bond strength to resin cement

  • Maciel, Lucas Campagnaro;Amaral, Marina;Queiroz, Daher Antonio;Baroudi, Kusai;Silva-Concilio, Lais Regiane
    • The Journal of Advanced Prosthodontics
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    • 제12권5호
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    • pp.291-298
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    • 2020
  • PURPOSE. The aim of this study is to evaluate the influence of repeated surface treatments on wettability and surface roughness for zirconia surface and bond strength of zirconia-based ceramics to resin cement. MATERIALS AND METHODS. Seventy blocks (10 × 10 × 3 mm) of zirconia-based ceramics were fabricated and divided into two groups according to the surface treatments: (A) 110 ㎛ Al2O3 airborne-particle abrasion and (R) 110 ㎛ silica modified Al2O3 airborne-particle abrasion. At stage 2, each group was subdivided into 5 groups according to the surface retreatments: (a) 110 ㎛ Al2O3 airborne-particle abrasion, (r) 110 ㎛ silica modified Al2O3 airborne-particle abrasion, (D) diamond bur, (Da) diamond bur + 110 ㎛ Al2O3 airborne-particle abrasion, and (Dr) diamond bur + 110 ㎛ silica modified Al2O3 airborne-particle abrasion. Cylinders of self-adhesive resin cement were cemented onto each treated ceramic surface and subjected to micro-shear bond strength test. Additional specimens were prepared for roughness and wettability analyses. The data were subjected to t-test and One-way ANOVA followed by Tukey's post hoc test (α=.05). RESULTS. At stage 1, group R presented higher bond strength values than group A (P=.000). There was a statistically significant increase of bond strength at stage 2 for group A (P=.003). The diamond bur influenced the surface roughness, increasing the values (P=.023). Group R provided better wettability. Regardless of the applied surface treatment, most of failures were adhesive. CONCLUSION. The combination of application and reapplication of Rocatec Plus showed the best results of bond strength. Surface retreatment and recementation might be an indicated clinical strategy.

상용 Al2O3 분말의 비교분석 및 이를 이용하여 제조한 슬러리의 분산 특성 (Comparative Analysis of Commercial Al2O3 Powders and the Dispersion Characteristics of Slurries Produced Using Them)

  • 권모세;유승준;김진호;정경훈;이종근;김응수
    • 한국재료학회지
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    • 제34권1호
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    • pp.27-33
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    • 2024
  • Al2O3 has excellent sintering properties and is important in semiconductor manufacturing processes that require high-temperature resistance and chemical inertness in a plasma environment. In this study, a comprehensive analysis of the chemical characteristics, physical properties, crystal structure, and dispersion stability of three commercially available Al2O3 powders was conducted. The aim was to provide a technological foundation for selecting and utilizing appropriate Al2O3 powders in practical applications. All powders exhibited α-Al2O3 as the main phase, with the presence of beta-phase Na2O-11Al2O3 as the secondary phase. The highest Na+ ion leaching was observed in the aqueous slurry state due to the presence of the secondary phase. Although the average particle size difference among the three powders was not significant, distinct differences in particle size distribution were observed. ALG-1SH showed a broad particle size distribution, P162 exhibited a bimodal distribution, and AES-11 displayed a uniform unimodal distribution. High-concentration Al2O3 slurries showed differences in viscosity due to ion release when no dispersant was added, affecting the electrical double-layer thickness. Polycarboxylate was found to effectively enhance the dispersion stability of all three powders. In the dispersion stability analysis, ALG-1SH exhibited the slowest sedimentation tendency, as evidenced by the low TSI value, while P162 showed faster precipitation, influenced by the particle size distribution.

선택적 CO 산화 반응을 위한 Ru/$\alpha-Al_2O_3$ 촉매 고분산 제조 방법에 관한 연구 (Preparation of Highly Dispersed Ru/$\alpha-Al_2O_3$ Catalyst for Preferential CO Oxidation)

  • 엄현지;구기영;정운호;이영우;윤왕래
    • 한국수소및신에너지학회논문집
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    • 제21권5호
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    • pp.390-397
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    • 2010
  • 0.5wt% Ru/$\alpha-Al_2O_3$ catalysts are prepared by deposition-precipitation method for the preferential CO oxidation In order to investigate the effect of pH on the Ru dispersion and particle size, the pH of precursor solution is adjusted to between 5.5 and 9.5. 0.5wt% Ru/$\alpha-Al_2O_3$ catalyst prepared at the pH of 6.5 has high Ru dispersion of 17.9% and small particle size of 7.7nm. In addition, 0.5wt% Ru/$\alpha-Al_2O_3$ catalyst prepared at the pH 6.5 is easily reduced at low temperatures below $150^{\circ}C$ due to high dispersion of $RuO_2$ particle and shows high CO conversion over 90% in the wide temperature range between $100^{\circ}C$ and $160^{\circ}C$. Moreover, the deposition-precipitation is a feasible method to improve the Ru dispersion as compared to the impregnation method. The 0.5wt% Ru/$\alpha-Al_2O_3$ catalyst prepared by deposition-precipitation exhibits higher CO conversion than 0.5wt% Ru/$\alpha-Al_2O_3$ catalysts prepared by impregnation due to higher metal dispersion and better reducibility at low temperature.

원심분사주조법에 의한 $Cu-X(=Al_2O_3,W)_p$ 복합재료의 미세조직 및 복합화 (Compositing Modes and Microstructures of $Cu-X(=Al_2O_3,W)_p$ Composite by Centrifugal Spray-Cast Deposition)

  • 배차헌;정해용
    • 한국주조공학회지
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    • 제17권5호
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    • pp.480-487
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    • 1997
  • Particle reinforced metal matrix composites(MMCs) via a centrifugal spray-cast deposition(CSD) process were fabricated by injecting second phase particles($Al_2O_3$<40${\mu}m$, W<17.3${\mu}m$) into copper melt on the atomizing disc. Compositing modes were investigated by combining microstructures and mathematical modeling between Cu droplets and the reinforced particles injected. The $Cu/W_P$ powders were shown that the W particles penetrate and get embedded in the Cu droplets. It is considered that the W particles composite preferentially in Cu melt on the atomizing disc. On the other hand, the $Al_2O_3$, particles did not penetrate into the Cu droplets on the atomizing disc but get attached in surface of Cu droplets during the flight. It is considered that the compositing may be attained in the flight distance which the relative velocity between Cu droplet and $Al_2O_3$, particle is maximum. The microstructure of the $Cu/W_P$ and the $Cu/(Al_2O_3)_p$ composite preform was strongly influenced by compositing modes of droplets, and after subsequent deposition it was comprised as it is called the dispersed type and the cell type of microstructure, respectively.

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입도분포에 따른 하상퇴적물의 지구화학적 분산 및 부화 (Geochemical Dispersion and Enrichment of Fluvial Sediments Depending on the Particla Size Distribution)

  • 이현구
    • 자원환경지질
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    • 제32권3호
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    • pp.247-260
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    • 1999
  • Geochermical characteristics of the fluvial sediments deprnding on particle size distribution size were investigated in the respect of majir, minor and rare eath element chemisitry. Ratios of $Al_{2}O_{3}/Na_{2}O$ and $K_{2}O/Na_{2}O$ of the sediments show the homogeneous valus, and partly positive correlation with $SiO_{2}/Al_{2}O_{3}$, respecively. Characteristics of minor element ratios (V/Ni, Cr/V, Ni/Co and Zr/Hf)are within the lower and narrow range. Thesesuggested that sediment sources may be acidic to intermediate granitic rock, and may be explained by simple weathering and sedimentation. With increasing SiO2 contents, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO and MgO decreased, but those of $K_{2}O$ and $Na_{2}O$ increased, Concentrations of Ba, Be, Cs, Cu, Li, Ni, Sr, V and Zr show comparatively normal negative and some positive trends. Compared with the mean composition of granite, concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, MnO, CaO and MgO in the sediments of the study area were highly enriced. Among some minor and rare earth elements, concentrations of As, Cd, Cu, and V were enriched, but those of Be, Ce, Rb, Sc, Sr and Zn were depleted when compared with average composition of granite. By decreasing of particle size fractions, SiO2, Rb and Sr conterts decreased, but concentrations of $Al_{2}O_{3}$, $Fe_{2}O_{3}$, CaO, MgO, $TiO_{2}$, MgO, $P_{2}O_{5}$, Be, Cu, Hf, Pb, V and Zr increased. From the correlations between particle size fractions and element concenreations, some elements of $Fe_{2}O_{3}$, CaO, MgO, $P_{2}O_{5}$, Cu, Ni, Zn and Zr showed typical trends in the secondary contramination sediments. These trends are typically shown under 100 mesh fractions. It indicates that the fraction of minus 100 mesh is the optimum size fraction for geochemical and environmental survey.

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용탕교반법에 의한 $Al_2O_{3(p)}$/LXA복합재료의 기계적 성질에 관한 연구 (A study on the Mechanical Properties of $Al_2O_{3(p)}$/LXA Composites by Melt-stirring Method)

  • 이현규;공창덕
    • 한국추진공학회지
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    • 제4권1호
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    • pp.65-73
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    • 2000
  • 금속기지 복합재료의 주조는 폭넓은 재료의 선택과 공정조건들을 제공하는 좋은 공정이다. 용탕교반기술은 압착주조 또는 분말야금과 비교하면 매우 간단하고 값이 싸기 때문에 주조방법중에서 산업응용에 가장 널리 쓰이는 좋은 방법이다. 최근에는 $\alpha$ -$Al_2O_{3(p)}$/Lo-Ex alloy 복합재료의 입자크기, 입자의 부피 분율, 기계적 성질에 있어서 Mg첨가 그리고 열팽창계수 등이 연구되어 왔다. $\alpha$ -$Al_2O_3$는 입자계면과 기지에 형성되어 기계적 성질에 중요한 역할을 하였다 대부분 복합재료의 인장강도는 증가하지 않지만 16$\mu\textrm{m}$ $\alpha$ -$Al_2O_3$ 입자를 5vol%로 첨가한 경우, 3wt.% Mg를 첨가한 복합재료의 인장강도는 증가한다. 강화재의 부피분율과 mg은 복합재료의 열팽창계수를 감소시켰다.

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