In this study, a ZnS film of 8-mm thickness was prepared on graphite using a hot-wall-type CVD technique. The ZnS thick film was then hot isostatically pressed under different pressures (125–205 MPa) in an argon atmosphere. The effects of pressure were systematically studied in terms of crystallographic orientation, grain size, density, and transmittance during the HIP process. X-ray diffraction pattern analysis revealed that the preferred (111) orientation was well developed after a pressure of 80 MPa was applied during the HIP process. A high transmittance of 61.8% in HIPZnS was obtained under the optimal conditions (1010°C, 205MPa, 6 h) as compared with a range of approximately 10% for the CVD-ZnS thick film under a 550-nm wavelength. In addition, the main cause of the improvement in transmittance was determined to be the disappearance of the scattering factor due to grain growth and the increase in density.

This study is performed to fabricate a Ti porous body by freeze drying process using titanium hydride (TiH2) powder and camphene. Then, the Ti porous body is employed to synthesize carbon nanotubes (CNTs) using thermal catalytic chemical vapor deposition (CCVD) with Fe catalyst and methane (CH4) gas to increase the specific surface area. The synthesized Ti porous body has 100 μm-sized macropores and 10-30 μm-sized micropores. The synthesized CNTs have random directions and are entangled with adjacent CNTs. The CNTs have a bamboo-like structure, and their average diameter is about 50 nm. The Fe nano-particles observed at the tip of the CNTs indicate that the tip growth model is applicable. The specific surface area of the CNT-coated Ti porous body is about 20 times larger than that of the raw Ti porous body. These CNT-coated Ti porous bodies are expected to be used as filters or catalyst supports.

In this study, titanium(Ti) meshes and porous bodies are employed to synthesize carbon nanotubes(CNTs) using methane(CH₄) gas and camphene solution, respectively, by chemical vapor deposition. Camphene is impregnated into Ti porous bodies prior to heating in a furnace. Various microscopic and spectroscopic techniques are utilized to analyze CNTs. It is found that CNTs are more densely and homogeneously populated on the camphene impregnated Ti-porous bodies as compared to CNTs synthesized with methane on Ti-porous bodies. It is elucidated that, when synthesized with methane, few CNTs are formed inside of Ti porous bodies due to methane supply limited by internal structures of Ti porous bodies. Ti-meshes and porous bodies are found to be multi-walled with high degree of structural disorders. These CNTs are expected to be utilized as catalyst supports in catalytic filters and purification systems.

Citations

Citations to this article as recorded by  

• Solvent induced surface modifications on hydrogen storage performance of ZnO nanoparticle decorated MWCNTs
  Madhavi Konni, Anima S. Dadhich, Saratchandra Babu Mukkamala
  Sustainable Energy & Fuels.2018; 2(2): 466.     CrossRef
• Influence of nickel nanoparticles on hydrogen storage behaviors of MWCNTs
  Ye-Ji Han, Soo-Jin Park
  Applied Surface Science.2017; 415: 85.     CrossRef

Leaching of MOCVD dust in the LED industry is an essential stage for hydro-metallurgical recovery of pure Ga and In. To recover Ga and In, the leaching behavior of MOCVD scrap of an LED, which contains significant amounts of Ga, In, Al and Fe in various phases, has been investigated. The leaching process must be performed effectively to maximize recovery of Ga and In metals using the most efficient lixiviant. Crystalline structure and metallic composition of the raw MOCVD dust were analyzed prior to digestion. Subsequently, various mineral acids were tested to comprehensively study and optimize the leaching parameters such as acidity, pulp density, temperature and time. The most effective leaching of Ga and In was observed for a boiling 4 M HCl solution vigorously stirred at 400 rpm. Phase transformation of GaN into gallium oxide by heat treatment also improved the leaching efficiency of Ga. Subsequently high purity Ga and In can be recovered by series of hydro processes.

Citations

Citations to this article as recorded by  

• Selective Solvent Extraction of In from Synthesis Solution of MOCVD Dust using D2EHPA
  Byoungyong Im, Basudev Swain, Chan Gi Lee, Jae Layng Park, Kyung-Soo Park, Jong-Gil Shim, Jeung-Jin Park
  Journal of the Korean Institute of Resources Recycling.2015; 24(5): 80.     CrossRef
• Fabrication of High Purity Ga-containing Solution using MOCVD dust
  Duk-Hee Lee, Jin-Ho Yoon, Kyung-Soo Park, Myung-Hwan Hong, Chan-Gi Lee, Jeung-Jin Park
  Journal of the Korean Institute of Resources Recycling.2015; 24(4): 50.     CrossRef
• Influence of Oxidation Temperatures on the Structure and the Microstructure of GaN MOCVD Scraps
  Hyun Seon Hong, Joong Woo Ahn
  journal of Korean Powder Metallurgy Institute.1970; 22(4): 278.     CrossRef