직접 발포법을 이용해 제조된 실리카 흄-SiO2계 다공성 세라믹의 열적 특성
Thermal properties of silica fume-SiO2 based porous ceramic fabricated by using foaming method
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무기질 단열재 개발을 위해 포말법을 이용하여 다공성 세라믹스를 제조하였다. 실리카 흄과 SiO2를 주 원료로 사용하였으며, 다공성 세라믹의 균일한 기공 형성을 위한 첨가제로 벤토나이트를 사용하였다. 다공성 세라믹은 1200°C에서 소결하였으며, 기공율, 밀도, 압축강도, 미세구조 그리고 열전도도 분석을 수행하였다. 다공성 세라믹은 SiO2에 대한 실리카흄의 함량이 70~90 % 증가할수록 비중이 0.63에서 0.69로 증가하였으며, 압축강도는 9.41Mpa에서 12.86 Mpa로 증가하였다. 그러나, 기공율은 비중과 반대로 72.07 %에서 70.82 %로 감소하는 경향을 나타내었다. 열전도도 측정 결과, 실리카 흄의 함량이 70 %인 F7S3 다공성 세라믹의 경우 25~800°C 온도조건에서 0.75~0.72W/m∙K의 열전도도를 나타내었으며, 실리카 흄의 함량이 90%인 F9S1 다공성 세라믹의 경우 0.66~0.86W/m∙K를 나타내어 실리카 흄 함량이 적을수록 낮은 열전도도를 나타내었다. 이는 기공율 결과와 일치한 것을 확인하였다. SEM(Scanning Electron Microscope)을 이용한 미세구조 분석 결과, 다공성 세라믹 내/외부에 전체적으로 수십~수백µm 범위 기공이 관찰되었으며 기공 분포가 비교적 균일한 것을 확인할 수 있었다.
Abstract
Porous ceramics were manufactured using the foaming method for the development of inorganic insulating materials. Silica fume and SiO2 were used as main raw materials, and bentonite was used as a rapid setting agent for uniform structure formation of porous ceramics. The porous ceramics were sintered at 1200°C, and porosity, density, compressive strength, microstructure and thermal conductivity were analyzed. As the content of silica fume to SiO2 of the porous ceramics increased 70 to 90 %, the specific gravity increased from 0.63 to 0.69, and the compressive strength increased from 9.41 Mpa to 12.86 Mpa. But, the porosity showed a tendency to decrease from 72.07 % to 70.82 %, contrary to the specific gravity. As a result of measuring the thermal conductivity, the porous ceramic with a silica fume content of 70 % showed a thermal conductivity o f 0.75 to 0 .72W/m∙K at 25 t o 800°C, respectively, and, another that a silica fume content of 90 % showed a 0.66~0.86W/m∙K. So the l ower t he s ilica f ume content, t he l ower t he t hermal c onductivity, which w as c onfirmed to b econsistent with porosity result. As a result of microstructure analysis using SEM (Scanning Electron Microscope), pores in the range of tens to hundreds µm were observed inside and outside the porous ceramic, and it was confirmed that the pore distribution was relatively uniform.
참고문헌 (26)
- R.C. Lewis, "Properties of fresh and hardened concrete containing supplementary cementitious materials Vol. 3", pp.99~ (2018), Springer
- F. Sanchez, "Microstructure and macroscopic properties of hybrid carbon nanofiber", silica fume cement composites, 2009, pp.69, 1310~
- H. M. Khater, "Effect of silica fume on the characterization o f the geopolymer materials", Int. J. Adv. Struct, 5, pp.12~ (2013)
- 문영표, "플라즈마토치 용융로 운전경험을 통한 내화물 수명 증진 방안", Journal of Nuclear Fuel Cycle and Waste Technology, 14(2), pp.169~178 (2016), 한국방사성폐기물학회
- A. Watanabe, "Mechansim of dense magnesia layer formation near the surface of magnesia-carbon brick", J. Am. Ceram. Soc, 69, pp.213~ (1986)
- M. Hamidouche, "Thermal shock behavior of mullite ceramic", Ceram. Int, 29, pp.599~ (2003)
- Z. Živcová, "Thermal conductivity of porous alumina ceramics prepared using starch as a pore-forming agent", J. Eur. Ceram. Soc, 29, pp.347~ (2009)
- K. Andreev, "Thermal and mechanical cyclic tests and fracture mechanics parameters as indicators of thermal shock resistance-case study on silica refractories", J. Eur. Ceram. Soc, 39, pp.1650~ (2019)
- K. Andreev, "Cyclic fatigue of silica refractories-effect of test method on failure process", J. Eur. Ceram. Soc, 37, pp.1811~ (2017)
- E. Gregorová, "Temperature dependence of dampling in silica refractories measured via the impulse excitation technique", Ceram. Int, 44, pp.8363~ (2018)
- C. Sadik, "Recent advances in silica-alumina refractory : A review", J. Asian Ceram. Soc, 2, pp.83~ (2014)
- H. Lu, "Effect of Al2O3 powder on properties of fumed silica thermal insulating composites using mechanofusion technique", Appl. Mech. Mater, 148-149, pp.1011~ (2012)
- Y. Dai, "Effect of the phase transformation on fracture behavior of fused silica refractories", J. Eur. Ceram. Soc, 38, pp.5601~ (2018)
- C. N. Djangang, "Sintering behaviour of porous ceramic kaolin-corundum composites : phase evolution and densification", Mater. Sci. Eng. A. Struct. Mater, 528, pp.8311~ (2011)
- T. Shimizu, "Thermal conductivity of high porosity alumina refractory bricks made by a slurry gelation and foaming method", J. Eur. Ceram. Soc, 33, pp.3429~ (2013)
- P. Sepulveda, "Gelcasting foams for porous ceramics", J. Am. Ceram. Soc, 76, pp.61~ (1997)
- D. J. Green, "Fabrication and mechanical properties of lightweight ceramics produced by sintering of hollow spheres", J. Am. Ceram. Soc, 68, pp.403~ (1985)
- Ashish Pokhrel, "Processing of Porous Ceramics by Direct Foaming: A Review", 한국세라믹학회지, 50(2), pp.93~102 (2013), 한국세라믹학회[DOI]
- W. Ramsden, "Separation of solids in the surface-layers of solutions and ‘suspensions’(observations on surfacemembranes, bubbles, emulsions, and mechanical coagulation). -Preliminary account", Proc. R. Soc. Lond, 72, pp.477~ (1904)
- S. U. Pickering, "Pickering : emulsions", J. Chem. Soc, 91, pp.2001~ (2001)
- H. Schneider, "Structure and properties of mullite-a review", J. Eur. Ceram. Soc, 28, pp.329~ (2008)
- R.W. Powell, "Thermal conductivity of selected materials Vol. 8", pp.99~ (1966), U. S. Dept. of Commerce
- D. H. Olson, "Local thermal conductivity measurements to determine the fraction of α-cristoblaite in thermally grown oxides for aerospace applications", Scr. Mater, 177, pp.214~ (2020)
- W. Yan, "Effect of particle size on microstructure and strength of porous spinel ceramics prepared by pore-forming in situ technique", Bull. Mater. Sci, 34, pp.1109~ (2011)
- S. Bhanja, "Influence of silica fume on the tensile strength of concrete", Cem. Concr. Res, 35, pp.743~ (2005)
- R. Duval, "Influence of silica fume on the workability and the compressive strength of highperformance concretes", Cem. Concr. Res, 28, pp.533~ (1998)