Thermally stable insulating elements based on refractory ceramic fibres

摘要

In a refractory heat insulating element formed of mechanically associated refractory ceramic fibres contg.≥97.5 wt.% total of alumina, silica and zirconia, the improvement is that (a) the element is free from organic or mineral binder; (b) the fibres have the compsn. (by wt.) 33-45% Al2O3, 41-53% SiO2, 5.5-17% ZrO2, 0.02-2% MgO and 0.50% other oxides, with max. 0.20% Fe2O3 + TiO2 and max. 0.30% Na2O + CaO + K2O; (c) the fibres have 30-64% crystallinity in homogeneous manner throughout the element, the crystals being formed of mullite and tetragonal zirconia crystals; and (d) the element has a linear contraction of max. 3% after holding for 24 hrs. at 1450 degrees C..