Korean | English

pISSN : 1225-1429 / eISSN : 2234-5078

2020 KCI Impact Factor : 0.17
Home > Explore Content > All Issues > Article List

2019, Vol.29, No.2

  • 1.

    SiC aggregates synthesized from carbonized rice husks, paper sludge, coffee grounds, and silica powder

    Kyoung-Wook Park | Young-Hoon Yun | 2019, 29(2) | pp.45~49 | number of Cited : 0
    Abstract PDF
    Relatively fine silicon carbide (SiC) crystalline aggregates have been synthesized with the carbonized rice husks, paper sludge, coffee grounds as the carbon sources and the silica powder. The main reaction source to obtain silicon carbide (SiC) aggregates from the mixture of carbon sources and silica was inferred as the gaseous silicon monoxide (SiO) phase, being created from this mixture through the carbothermal reduction reaction. The silicon carbide (SiC) crystalline aggregates, fabricated from the carbonized rice husks and paper sludge, coffee grounds and silica (SiO2) powder, were investigated by XRD patterns, FE-SEM and FE-TEM images. In these specimens, obtained from the carbonized rice husks, paper sludge and silica, XRD patterns showed rather high strong peak of (111) plane near 35 o . The FE-TEM images and patterns of specimens, synthesized from carbonized rice husks, paper sludge, coffee grounds and silica under Ar atmosphere, showed relatively fine particles under 1 μm and crystalline peak (110) of silicon carbide (SiC) diffraction pattern.
  • 2.

    Application of rapid thermal annealing process to the aluminum induced crystallization of amorphous silicon thin film

    황지현 | 양수원 | KIM YOUNG KWAN | 2019, 29(2) | pp.50~53 | number of Cited : 0
    Abstract PDF
    In this study, polycrystalline silicon thin film useful for the solar cells was fabricated by AIC(Aluminum Induced Crystallization) process. A diffusing barrier for this process is prepared with Al2O3. For the maximization of the grain size of the polycrystalline silicon, a selective blasting of the Al2O3 diffusing barrier was conducted before annealing treatment. The heat treatment for the activation of the amorphous-Si (a-Si) layer was carried out with Rapid Thermal Annealing (RTA) process. Crystallization of the a-Si layer was analyzed with XRD. It was confirmed that a-Si was crystallized at 500 o C and the silicon crystal is observed to be formed and the grain size of the polycrystalline silicon was observed to be 15.9 μm.
  • 3.

    The effect of silica composite properties on DLP-stereolithography based 3D printing

    Jin-Woo Lee | Nahm, Sahn | Kwangtaek Hwang and 3other persons | 2019, 29(2) | pp.54~60 | number of Cited : 2
    Abstract PDF
    Recently, various composite materials for additive manufacturing are interested to expand the application field of 3D printing. 3D printing technique was mainly developed using polymer, and ceramic materials for 3D printing are still in the early stage of research due to the requirement of high solid content and post treatment process. In this study, silica particles with various diameters were surface treated with silane coupling agent, and synthesized as silica composite with photopolymer to apply DLP 3D printing process. DLP is an additive manufacturing technology, which has high accuracy and applicability of various composite materials. The rheological behavior of silica composite was analyzed with various solid contents. After DLP 3D printing was performed using silica composites, the printing accuracy of the 3D printed specimen was less than about 3 % to compare with digital data and he bending strength was 34.3 MPa at the solid content of 80 wt%.
  • 4.

    Surface characteristics for thermal diffusion of FA-BFS-based geopolymer ceramics added alumina aggregate

    Jinho Kim | Hyun Park | Kim Kyung Nam | 2019, 29(2) | pp.61~70 | number of Cited : 0
    Abstract PDF
    Geopolymer is an eco-friendly construction material that has various advantages such as reduced CO2 emission, fire resistance and low thermal conductivity compared to cement. However, it has not been many studies on the thermal behavior of the surface of the geopolymer panel when flame is applied to the surface. In this study, surface characteristics of hardened geopolymer on flame exposure was investigated to observe its characteristics as heat-resistant architectural materials. External structure changes and crack due to the heat shock were not observed during the exposure on flame. According to the residue of calcite and halo pattern of aluminosilicate gel, decarboxylation and dehydration were extremely limited to the surface and, therefore, it is thought that durability of hardened geopolymer was sustained. Gehlenite and calcium silicate portion was inversely proportional to quartz and calcite and significantly directly proportional to BFS replacement ratio. Microstructure changes due to the thermal shock caused decarboxylation and dehydration of crystallization and it was developed the pore and new crystalline phase like calcium silicate and gehlenite. It is thought that those crystalline phase worked as a densification and strengthening mechanism on geopolymer panel surface.
  • 5.

    Fabrication and characteristics of TiO2 coating solution with silica-based inorganic binder

    강우규 | Hye Jin Kim | Kim Jinho and 2other persons | 2019, 29(2) | pp.71~76 | number of Cited : 1
    Abstract PDF
    Recently, the demand of labels for product management is increasing, as the automation system becomes more common. the development of functional labels which can be used in various environments has been rapidly proceeded. In the case of a printed circuit board, barcode labels with thermal and chemical stability are generally used due to a high temperature process around 300 o C and chemical cleaning in the manufacturing process. However, the yellowing phenomenon of labels that can lower the resolution of printed barcode image still needs to be prevented. In this study, we prepared a composite coating layer using a silica inorganic binder and a titanium dioxide white pigment, and developed a functional labels with thermal and chemical stability. The silica inorganic binder prepared by sol-gel process was confirmed to show excellent adhesion and abrasion resistance with the polyimide film. The white coating layer could be formed on the polyimide film with mixing the silica inorganic binder and titanium dioxide white pigment. The prepared coating layer showed excellent whiteness and glossiness above 400 o C. The excellent chemical stability of the coating layer was also confirmed by the chemical treatment with acidic (pH 1.6) and basic (pH 13.6) cleaners.
  • 6.

    Fabrication of nanoporous ceramic membrane for water treatment

    Hyuksu Han | LeeHoJun | Ryu, Jeong-ho | 2019, 29(2) | pp.77~81 | number of Cited : 0
    Abstract PDF
    Recently, as the problem of environmental pollution emerges, various methods of eco-friendly water treatment method are being developed. Polymer membranes, which are currently leading the market, are inexpensive, but have many problems in terms of chemical resistance and durability. Thus, ceramic membrane has been attracted great attention as highefficiency water treatment due to excellent durability and chemical resistant. In this study, ceramic membranes were developed via pore structure, size control, and surface treatment. The pore size of the membrane was controlled through the formation of ZrO2 and TiO2 coating films. Tape casting and sol-gel process were used to form a ceramic coating film with nanopores on the surface of the membrane. Microstructure analysis of ceramic membrane and pore size analysis of the coating film were conducted and the change of water treatment characteristics was observed.