Mullite Fibre Mats by a Sol-Gel Spinning Technique |
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Authors: | M Chatterjee MK Naskar PK Chakrabarty D Ganguli |
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Institution: | (1) Sol-Gel Division, Central Glass & Ceramic Research Institute, Kolkata 700 032, India |
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Abstract: | Fine grained, microcrystalline mullite (Al4+2x
Si2–2x
O10–x) fibre mats with a web-like structure were fabricated by a sol-gel spinning technique using a multi-orifice spinneret. Points of contact in gel fibre mats helped in the formation of a web-like fibrous body having reasonable strength and very little dust formation after calcination. Strong and resilient fibres with diameters in the range 3–12 m were obtained by a single-step sol-gel method from spinnable sols devoid of organics as the binder aid. Crystallization of -alumina and mullite at about 900°C and 1250°C, respectively was confirmed by differential thermal analysis (DTA) and X-ray diffraction (XRD). Thermogravimetry (TG) indicated the removal of most of the volatiles at about 500°C accompanied by a weight loss of about 48%. Scanning electron microscopy (SEM) shows the presence of small grains (80–150 nm in size) in the fibres calcined at 1250°C. Fourier transformed infrared spectroscopy (FTIR) indicated the sequence of transformations taking place during heat-treatment of gel fibres at different temperatures. The individual fibres in the mats calcined at 1250°C exhibited a tensile strength of 1300–1600 MPa. |
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Keywords: | sol-gel processes mullite fibres refractories |
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