Papers by Keyword: High Purity

Abstract: This paper aims to synthesize high purity nano-sized silica from rice husk ash (RHA) by chemical method and investigate its physical and chemical properties. Through a controlled burning of rice husk, the white-colored RHA is obtained. Next, the RHA is subjected to the pre-treatment of acid leaching and thermal treatment. The synthesizing process has been done through the precipitation method. The EDX and FTIR analysis confirmed that the prepared powder consists of high purity silica particles through the detection of characteristic peaks of O and Si elements and the presence of primary bonds in silica, which are silanol groups and siloxane bonds. Meanwhile, the FESEM micrograph shows that silica particles in nano-scale had been obtained with an average diameter of 74.0 nm – 84.0 nm. The XRF and XRD analysis confirmed that the prepared powder yields 99.68% nano-silica in an amorphous structure.

Abstract: This study develops a fast and simple way to produce high purity magnetite (Fe₃O₄) microparticles from mill scale by using hydrogen reduction with the addition of vapour as a retarding agent. By optimising the reduction temperature and gas flow rate, the characterisations by X-ray diffractometry technique shown that the Fe₃O₄ fraction of over 93 wt.-% is shown at the reduction temperature of 550 – 650 oC with the flow rate of the 4.5-5.5 mol%H₂ + Ar gas + H₂O gas mixture from 100 – 200 ml/min. The highest Fe₃O₄ fraction of over 99 wt.-% can be achieved from the reduction with the mixed gas at 650 oC and the flow rate of 200 ml/min for 4 hour.

Abstract: The preparation methods of high performance ferromagnetic sputtering targets (including cobalt, nickel-platinum and nickel-iron alloy) for advanced semiconductor manufacturing were introduced. The properties of sputtering target, such as pass-through-flux (PTF), and grain size which affect the sputtering performance were well controlled by proper fabrication technique. The key factors that affect sputtering performance were also discussed.

Abstract: Tungsten has many excellent properties such as high melting point, high electrical conductivity, high electromigration resistance, high electron emission coefficient, high thermal stability and so on. Because of these excellent properties, high purity tungsten targets have wide applications and development prospects in the integrated circuit (IC) industry. In this paper, some manufacturing methods of tungsten targets was summarized and analyzed. The high melting point of tungsten makes powder metallurgy (PM) be the manufacturing methods of tungsten targets. After preforming of the tungsten powders, some sintering and densification processes like atmosphere pressure sintering, Hot Pressing (HP), Hot Isostatic Pressing(HIP) have been carried out. The grain size and the density of the tungsten targets is different by different manufacturing methods.

Abstract: MgO ceramics with the purity higher than 99.99% have been fabricated by a hot-isostatic press (HIP) technique of hot-pressed MgO compacts using nanometer MgO powder with an average particle size of 300 nm. The densification and grain growth behavior of MgO compacts during HIP process were investigated. The results indicate that the high-purity MgO ceramic with an average grain size of 9.76 μm and a density approximately to the theoretical density can be obtained by HIP method at 1350°C and 150 MPa for 60 min. HIP can significantly enhance the densification process of MgO compacts and cause a slightly change of grain size distribution.

Abstract: Zirconia (ZrO₂) has excellent properties such as high toughness, high strength, thermal stability and high corrosion resistance. Thus, recent zirconia has been spotlighted as a dental material. Most of pure zirconia has been separated from zircon sand (ZrSiO₄) by wet refining process which is very complex and not an environmental. The arc plasma fusion method has the advantages as a sustainable process that can easily and quickly get very good fine and high pure powders from the original materials compared with traditional wet method. In this study, zircon sand is separated into zirconia and silica by using the Ar-H₂(hydrogen) arc plasma refining. And then silica is removed from it by the microwave leaching method to produce a high pure zirconia. Argon gas, hydrogen gas, copper anode and tungsten cathode are used for the plasma arc generation. To facilitate zirconia and silica separation, carbon of 1-3molar ratios are added with zircon sand. Plasma melting were sequentially conducted two processes. After a reduction process using Ar gas only, it was refined using a mixed gas of Ar-H₂. After melting and water cooling in chamber, the solid phases composed with zirconia and silica were obtained at 240 ̊C, and 20% sulfuric acid solution was used as the leaching materials to obtain a high purity zirconia (more than 99%).

Abstract: Ti/Si/C element powders were used to synthesize Ti₃SiC₂ by spark plasma sintering. The synthesized products consisted of Ti₃SiC₂, together with TiC and Ti₅Si₃ as impurities. The addition of Al, excess Si, and appropriate sintering temperature increased the purity of Ti₃SiC₂ in the products. From the 3Ti/1.2Si/2C/0.2Al mixture, Ti₃SiC₂ with the purity 99 mass % was synthesized at 1300 °C for 5 min at 30 MPa.

Abstract: High-purity precious metal and its alloy targets make a very important role in semiconductor manufacturing. In this paper, the preparation methods of high performance sputtering targets (including silver, platinum and its alloy, ruthenium materials) for advanced semiconductor manufacturing were introduced. The relationships between deposited film behaviors and sputtering target properties in some applications were also discussed. In order to acquire high quality thin film, the properties of sputtering target such as density, alloy composition homogeneity, grain size and uniformity et al. have to be well controlled by proper fabrication techniques.

Abstract: Two kinds of SiC powder having a different impurity contents and particle size were prepared by carbothermal reduction under different conditions from traditional process for controlling the purity of product. SiC single crystal was grown in the RF heating PVT machine at the temperature above 2,100 °C. After crystal growth, boule was cut to wafers in 1mm thickness and fine polished using diamond abrasive slurry. The impurity in the powder and wafer was analyzed using glow discharged mass spectroscopy (GDMS). Major impurities in the SiC wafer were aluminum, boron, iron and titanium which were accorded in the SiC powder and these impurities were decreasing in proportional to those in the powder. However, behavior of each elemental impurity was different from each other during the crystal growth. In case of boron was increased after crystal growth while aluminum decreased. In case of titanium and boron were higher in the wafer than in the powder. It can be explained to other impurity source such as graphite crucible and insulation felt.

Abstract: In this paper, the physical and chemical properties of LaB₆ Ceramics are introduced, the influence of fabrication techniques on the microstructure and properties of LaB₆ Ceramics are discussed. The combustion synthesis process was considered as the proper method for fabrication of LaB₆ Ceramic powder with high purity. The results showed that the control additive has a great influence on the synthesis processand the nanoLaB₆ Ceramic powder with high purity can be produced made when the content of the control additive is 30%.