Porous heat resistant insulation for e.g. filling cavities - is prepd. by reacting refractory powder, aq. acid, aluminium (alloy) in aluminium phosphate or calcium aluminate and/or alkali silicate

摘要

A porous heat resistant material is made by reacting a mixture of refractory powder, aq. acid and metal powder in the presence of a binder which is set by H2O. The ratio of liquid to solid is 1:1 to 1:4 pts. wt. The pref. metal is Al or its alloys. The pref. binder is AlPO4 or Ca(AlO2)2 and/or alkali silicate. The liquid component of the mix contains 40-50 wt.% AlPO4 and 0.5-5 wt.% H3PO4. The solid component 0.5-10 wt.% Al, 15-45 wt.% Ca (AlO2)2 2-12 wt.% alkali silicate. The rest is refractory material. The pH of the mix is adjusted to 2-3 with Na2B4O7. Up to 15 wt.% graphite may be included in the solid component. The material is used to procure porous, heat resistant fillings for cavities, etc. It can be cast in situ and does not need firing.