• Title/Summary/Keyword: slurry materials

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Physical Properties of Microencapsulated Phase Change Material Slurries (미립잠열슬러리의 물성에 관한 실험적 연구)

  • 이효진;홍재창;이재구
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.9
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    • pp.860-869
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    • 2000
  • The thermal conductivity and density of slurries entrained with the particles of Micro-PCM are measured with respect to its temperatures as well as concentrations. For the thermal conductivity of slurries, a device made from P.A. Hilton (Model No. H470) is adopted. There is a well-scaled 0.3 mm gap between shells into which the slurry is injected. The temperatures of the slurry are changed to $5~25^{\circ}C$ , for which it is controled by the supplied voltage and cooling water circulated around the outer shell. The concentrations of Micro-PCM slurries are varied from 5 wt% to 50 wt%. Some general equations such as Maxwell's equation, are evaluated for their applicability with Micro-PCM slurry. As a result, it happens to be some 20% discrepancy between the experiment and the applied equations. The density measurements of Micro-PCM slurry to its temperature and concentration are peformed by hydrometer. For the experiment, tetradecane encapsulated slurry (($t_m≒6^{\circ}C$) and a mixed wax ($t_m≒50^{\circ}C$) are tested. The temperature changes of tetradecane are applied for $0^{\circ}C\;to\;$20^{\circ}C$and a mixed wax for $20^{\circ}C\;to\;$60^{\circ}C$ and its concentrations are changed from 5 wt% to 30 wt%. The results are compared with a general equation and the referenced data. For the conclusion, the experimental result and a general equation are well agreed.

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A Study on CMP Properties of SnO2 Thin Film for Application of Gas Sensor (가스센서 적용을 위한 SnO2 박막의 CMP 특성 연구)

  • Lee, Woo-Sun;Choi, Gwon-Woo;Kim, Nam-Hoon;Park, Jin-Seong;Seo, Yong-Jin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.12
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    • pp.1296-1300
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    • 2004
  • SnO$_2$ is one of the most suitable gas sensor materials. The microstructure and surface morphology of films must be controlled because the electrical and optical properties of SnO$_2$ films depend on these characteristics. The effects of chemical mechanical polishing(CMP) on the variation of morphology of SnO$_2$ films prepared by RF sputtering system were investigated. The commercially developed ceria-based oxide slurry, silica-based oxide slurry, and alumina-based tungsten slurry were used as CMP slurry. Non-uniformities of all slurries met stability standards of less than 5 %. Silica slurry had the highest removal rate among three different slurries, sufficient thin film topographies and suitable root mean square(RMS) values.

Numerical Study on the Erosion Tendency of Centrifugal Slurry Pump Impeller for Thermal Power Plants (화력발전소용 원심 슬러리 펌프 임펠러의 침식경향 해석적 연구)

  • Cheon, Min-Woo;Lee, Chul-Hee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.2
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    • pp.101-108
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    • 2022
  • Centrifugal pumps are typically used in many slurry industries to transport solid materials. Solid particles in the slurry frequently shock the walls inside the pump, significantly abrading the flow path. Wear damage causes replacement of the pump components, which wastes manpower and time. Therefore, previous studies have been conducted on factors to improve efficiency and life time. This study identifies trends in pumps supplying lime to desulfurized devices from thermal power plants. The shear stress transport(SST) model is used to determine the erosion trend of the centrifugal pump that transfers lime slurry. The purpose of this study is to identify efficiency and erosion trends by selecting three of the various impeller design elements. The three impeller blade design variables mentioned above represent the inlet draft angle and blade angle of leading edge(L.E) and trailing edge(T.E). The maximum value of the erosion density rate tends to be similar to the Input power.

Lamination of Dielectric Layers by High Pressure Spray Coating for LTCC (고압 스프레이 코팅법에 의한 저온동시소성세라믹(LTCC) 유전체 층의 적층방법)

  • Lee, Jee-Hee;Kim, Young-Jin
    • Journal of the Microelectronics and Packaging Society
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    • v.13 no.3 s.40
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    • pp.33-38
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    • 2006
  • Aerosol slurry composed of dielectric materials, distilled water, and deflocculants was sprayed on the substrates, through a high-pressure spray gun as an aerosol. The coated layers were cofired together with $Al_{2}O_{3}$ substrates and green sheets on which the inner connectors were printed. Although the coating rate of coated layers strongly depended on slurry viscosity, spray shape, and the pressure of the spray gun, the coated density was not changed. Buried conductors were maintained as printed by high pressure spray coating method, because the pressing process was not used. At the optimum condition of air controller step 3-4 and slurry viscosity c.p 2000-4000, dense and uniform layers could be achieved. Comparing with conventional lamination process using green sheets, spray coating method enabled thin dielectric layers of $20{\sim}50{\mu}m$.

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Effect of pH in Sodium Periodate based Slurry on Ru CMP (Sodium Periodate 기반 Slurry의 pH 변화가 Ru CMP에 미치는 영향)

  • Kim, In-Kwon;Cho, Byung-Gwun;Park, Jin-Goo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.117-117
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    • 2008
  • In MIM capacitor, poly-Si bottom electrode is replaced with metal bottom electrode. Noble metals can be used as bottom electrodes of capacitors because they have high work function and remain conductive in highly oxidizing conditions. In addition, they are chemically very stable. Among novel metals, Ru (ruthenium) has been suggested as an alternative bottom electrode due to its excellent electrical performance, including a low leakage of current and compatibility to high dielectric constant materials. Chemical mechanical planarization (CMP) process has been suggested to planarize and isolate the bottom electrode. Even though there is a great need for development of Ru CMP slurry, few studies have been carried out due to noble properties of Ru against chemicals. In the organic chemistry literature, periodate ion ($IO_4^-$) is a well-known oxidant. It has been reported that sodium periodate ($NaIO_4$) can form $RuO_4$ from hydrated ruthenic oxide ($RuO_2{\cdot}nH_2O$). $NaIO_4$ exist as various species in an aqueous solution as a function of pH. Also, the removal mechanism of Ru depends on solution of pH. In this research, the static etch rate, passivation film thickness and wettability were measured as a function of slurry pH. The electrochemical analysis was investigated as a function of pH. To evaluate the effect of pH on polishing behavior, removal rate was investigated as a function of pH by using patterned and unpatterned wafers.

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