Porous refractory mouldings resistant to molten aluminium or iron - contain ceramic fibres and e.g. alumina, bonded by metal phosphate

摘要

Heat resisting composite material consists of a mixt. of (a) ceramic fibres and (b) 50-89 wt.% addns. selected from alumina, flake alumina, corundum and ZrO2. The material is bonded by a metal phosphate. The prod. has porosity 50%; Young's modulus 30,000-100,000 kg/cm2 and crushing strength 100 kg/cm2. The pref. material contains 2-10 wt.% of the phosphate making a chemical bond, and 9-48% fibres which contain 40% alumina. The pref. mfg. process consists of mixing fibres contg. alumina with powdered addns. (b) and the acid binder, followed by the slow addn. of 25 wt.% of the dry mixt. of water. The slurry is cast into moulds for setting, then dried at up to 200 degrees C. The mouldings may then be heated slowly to 800 degrees C. Commercially available binders using H3PO4, aluminium phosphate or aluminium chlorophosphate can be used; or a 50% soln. of aluminium monophosphate. Used for the handling, transport, purificn. and/or moulding of molten Al or cast iron. The material is highly resistant to, and is not easily wetted by molten Al or cast iron.