PURPOSE: To obtain a uniform alumina balloon having excellent heat insulating property and strength and high purity with good yield by coating a specific mixture around the combustible nucleus then subjecting the same to combustion by heating and sintering.
CONSTITUTION: An aq. slurry or org. solvent slurry contg. the Al(OH)3 and/or Al2O3 of ≤50μm obtd. by a Bayer process, org. binder (e.g.: PVA) and Al inorg. binder (e.g.: polyaluminum chloride) is sprayed around the combustible nucleus (e.g.: activated carbon grain) and is coated thereon by using a pan coater, etc. by which the granular material is obtd. Said material is then heated to 200W 700°C to burn away the above-described combustible nucleus and to obtain the hollow alumina body and thereafter the temp. is increased to 1,300W1,800°C which is the sintering temp. of alumina. The alumina balloon having 0.05 W several 10mm diameter is thus obtd.
URYU HIROMI
TOKUICHI HIROYUKI
AMITANI YOSHIBUMI
| JPS50161494A | 1975-12-27 |