0 0 Co-efficient of expansion 0 C to 800 C Softening Point Annealing Point Strain Point Operating Temp 0 Electrical resistivity (at 350 C) -7 0 5.5 X 10 cm / cm / C 0 1685C 0 1200C 0 1120 C0 1050 C 7 7 x 10 ohm cm Boron Free Transparent Silica Resistant to chemical attack Virtually unaffected by sulphuric, nitric and hydrochloric acids. Hot alkalies and certain metal oxides react on silica. It is attacked by hydrofluoric acid. At high temperatures, it is also attacked by phosphoric acid. 0 Continuous use of fused silica above 1000C leads to devitrification with formation of crystobalite which is a crystalline phase and will lead to breakage on repeated use. For accurate and long use, it is advisable to wash the articles in distilled water and alcohol to remove trace impurities. Heating fused quartz to elevated temperatures causes Sio to undergo dissociation. Consequently, when flame- 2 working fused quartz, there is a brand of haze or smoke which forms just outside the intensely heated region. This haze presumably forms because the Si0 recombines with 2 oxygen from the air (and perhaps water) and condenses as extremely small particles of amorphous Sio.2 Borosil Fused Silica 99.95% SiOsurpasses all of the desirable 2 chemical and weathering durability properties usually associated with opaque Silica ware. We manufacture as per IS and BS Standards. a) There is little or no visible surface change or damage to silica with prolonged exposure to water, atmospheric gases, contaminants, oxide of nitrogen and ozone. b) Attack does occur, on exposure to alkaline solution and acids at very high temperatures. c) Low expansion and hence excellent dimensional stability and thermal shock resistance. Quartz Ware Quartz Ware
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