Fiber-Lined Fast-Firing

The use of polycrystalline Al2O3 ceramic fibre for insulating large industrial equipment for production processes is described. The advantages of fibre linings over insulated firebrick (IFB) linings are noted. The Al2O3 fibres have an Al2O3 content greater than 72% and have already proved useful for laboratory furnaces. They are obtained from an aqueous solution of an Al salt, SiO2 sol and an organic polymer. The organic compounds are burnt out, and the inorganic salts disintegrate at 500-1000 C. The fibre is crystallised at temperatures up to 1400 C. Their shrinkage is significantly lower than that of aluminosilicate fibres. Vacuum-formed ceramic fibre products obtained by adding silica, mullite and alumina fillers and binders to the Al2O3 fibres can be used up to 1800 C. Fibre linings can also be optimised by applying Al2O3 fibre coatings, which increase surface reflection, save energy, decrease long-term shrinkage, and minimise chemical attack. Mullite, alumina and SiC anchors are used to mount boards, board modules and composite covers. The layout and design of vacuum-formed Al2O3 ceramic fibreboards on the hot face of fast firing furnaces operating at temperatures between 1650 and 1750 C is described. Al2O3 fibreboard composite composed of mullite- and alumina-bonded vacuum-formed ceramic fibre has a modular design, and enables the furnace to be designed to end user requirements (mainly rapid-fire, fast cycle produced parts). The importance of maintenance is noted. A demonstration installation of an Al2O3 fibreboard composite in place of an IFB lining on the backwall and roof of a 1750 C furnace is described.